Fish Eggr and Larvae of the Hauraki Gulf, New Zealand - Fisheries Research Bulletin No. 23 - by - Fisheries Research Division I. ew Zealand ...

Fish Eggr and Larvae of the Hauraki Gulf, New Zealand - Fisheries Research Bulletin No. 23 - by - Fisheries Research Division I. ew Zealand ...
Fisheries Research Bulletin No. 23

Fish Eggr and Larvae of the
Hauraki Gulf, New Zealand


                     J. Crossland

              Fisheries Research Division
  I.[ew Zealand Ministry of Agriculrure and Fisheries
Fish Eggr and Larvae of the Hauraki Gulf, New Zealand - Fisheries Research Bulletin No. 23 - by - Fisheries Research Division I. ew Zealand ...
Fish Eggr and Larvae of the
Hauraki Gulf, I.{ew Zealand
Fish Eggr and Larvae of the Hauraki Gulf, New Zealand - Fisheries Research Bulletin No. 23 - by - Fisheries Research Division I. ew Zealand ...
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Fish Eggr and Larvae of the Hauraki Gulf, New Zealand - Fisheries Research Bulletin No. 23 - by - Fisheries Research Division I. ew Zealand ...
Fisheries Research Bulletin No. 23

Fish Eggr and Larvae of rhe
Hauraki Gulf, New Zealand

                     J. Crosslan{
              Fisheries Research Division,
         Ministry of Agriculture and Fisheries,
               Wellington, New Zealand

              Fisheries Research Division
  It{ew Zea\and Ministry of Agriculture and Fisheries
Fish Eggr and Larvae of the Hauraki Gulf, New Zealand - Fisheries Research Bulletin No. 23 - by - Fisheries Research Division I. ew Zealand ...
Published by the New Zealand Ministry of
        Agriculture and Fisheries
                       ISSN 0l l0-1749

   R¿c¿iu¿d   28 February 1978; reuisíon   receiu¿d   4 June 1980
Jnvrs CRossI-AND has already used the distribution and abundance of the eggs
and larvae of snapper to assess the standing stocks of this most valuable species
in New Zealand's most important cornmercial fishery. llowever, despite the
rapid expansion of fishing effort over the past few years, our knowledge of the
available resources, even in the Hauraki Gulf, has remained meagre.
   The data in this bulletin not only add to our undeistanding of the other
species in the Hauraki Gulf, but are an important prerequisite to our
appreciation oÍ its significance as a spawning or nursery ground {or fisheries
elsewhere. At the same time, this type of information will be of value as a
background for integrated management of the total resources of the area in the
                                       G. DUNcAN Weucn,
                                       Director, Fisheries Research Division
INTRODUCTION                                                  il
MATERIALAND METHODS                                           1l
 Sampling and Sorting                                         1l
 Identific¿tion of Eggs and Lawae                             ll
 Descriptions of Eggs and Laruae                              t2
 Daø Presentation                                             l2

RESULTS                                                       l3
 Family Engraulidae                                           13

 Family Clupeidae                                             t4
 Family Muraenidae                                            t7
 Family Congridae                                             20
 Family Moridae. ..                                           20
 Family Exocoetidae                                           oq

 Family Trachichthyidae                                       22
 Family Zeidae ...                                            23
 Family Syngnathidae                                          23
 Family   Triglidae                                           23
 Family   Acanthoclinidae                                     2+
 Famiiy   Carangidae                                          26
 Family   Sparidae..   .                                      31
 Family Mugilidae                                             34
 Family Labridae                                              34
 Family Uranoscopidae                                         35
 Families Blenniidae, Clinidae, and Tripterygiidae            5t)

 Family Eleotridae                                            38
 Family Gempylidae                                            38
 Family Scombridae                                            38
 Family   Bothidae                                            +0
 Family   Pleuronectidae                                      4l
 Family   Balistidae                                          49
 Family   Diodontidae                                         5+

DISCUSSION                                                    56
 Sampling Period                                              56
 Effect of Temperature on Spawning..   .                      56
 Effect of Water Movements on Distribution of Larvae . ..     57

SUMMARY                                                       58

REFERENCES                                                    59

ACKNOWLEDGMENTS ...                                           59
    l. The Hauraki Gulf, showing places mentioned in the text                                                      l0
    2. Survey stations and study area                                                                              t2

    3. Distribution of anchovy eggs by cruises,      197 4-7 5     and I 975-76                             t.t-   I   5

    4. Numbers of ancÌíovy eggs within the study area, lg74-75 and 1975-76                                         l5
    5. Distribution of anchorry laruae by cruises, I 974-75 and          I   975-76    .. .                        l6
    6 Distribution   of pilchard eggs,4-8 November 1974                                                            t7

    7. Distribution of pilchard larvae by cruises, 1974-75 and 1975-76 ...                                         l8

    8. Numbers of pilchard larvae taken by cruises,          197   4-7 5 and I 975-76                              t9

    9. Cumulative distribution of sprat eggs, 1974-75 and 1975-76                                                  l9
10. Moray eel eggs                                                                                                 l9
II.     Cumulative distribution of moray eel eggs,      197 4-7 5                                                  20

12.     Morayeellarva ...                                                                                          20

I   3. Distribution of ahuru eggs by cruises,      197 +-7 5   and I 975-76                                        21

14. Numbers of ahuru eggs taken by cruises, 1974-75 and 1975-76                                                    22

15.     Ahu¡u   larvae     ..                                                                                      22

16. Numbers of ahuru larvae taken by cruises, 1974-75 and 1975-76

I 7.    Distribution of ahuru lawae by cruises, 1974-75 and 1975-76                                         23-24

18. Garfish larva                                                                                                  2+

19.     Roughylarva                                                                                                2+

20. Cumulative distribution of red gurnard eggs,197+-75 and 1975-76

21. Numbers of red gurnard eggs within the study area,1974-75 and 1975-76                                          2s

22. Cumulative distribution of red gurnard law¿e,              197 4-7 5     and I 975-76                          25

23. Rockfish larva                                                                                                 26

24. Cumulative distribution of rockfish larvae, 1974-75 and 1975-76...                                             26

25. Jack mackerel Trachuns noaae4landiae eggs                                                                      27

26. Distributionof jackmackerelT.noue¿elandiaøeggsbycruises,                       1974-75and 1975-76 ...          28

27. Numbers of jack mackerel T. noaaezelandia¿ eggs within the study area, 1974-75 and 1975-76                     29

28. Jack mackerel T. noaa¿zelandia¿lawae                                                                           29

29. Distributionof jackmackerelT.nooaez¿lundiaelaruaebycruises, 1974-75 and 1975-76                                30

30. Numbers of jack mackerel T. noaaezelandia¿lawae taken by cruises , I97 4-7 5 and I 975-76                      3t

3   I   Eggs of jack mackerel Trachutas decliuis                                                                   3l
32. Cumulative distribution of jack mackerel T. declitis eggs,1974-75 and 1975-76                                  J1

33. Snapper lawae                                                                                                  32

34. Distribution of snapper larvae by cruises,         197   4-7 5 and 197 5-7     6   ..                          JJ

35. Numbers of snapper laruae taken by cruises, Ì97,[-75 and 1975-76                                               5+

36. Yellow-eyed mullet egg                                                                                         34

    37. Cumulative distribution o{ yellow-eyed mullet eggs, 1974-75 anð 1975-76

                                larva                                                                                  35
    38. Yellow-eyed mullet              ..   .

          39. Spotty lawa                                                                                       35
          ,10. Spotted stargazer eggs

          41. Cumulative distribution of spotted stargazer eggs, 197,1-75 and 1975-76                           36

          42. Spotted stargazer larvae                                                                          JI

          43. Cumulative distribution of spotted stargazer larvae,       197 4-7 5     and I 975-76 ...
          .14.   Graham's gudgeon larvae

          45. Cumulative distribution of Graham's gudgeon laruae,.1974-75 and 1975-76                           39

          46. Blue mackerel egg                                                                                 39

          47. Numbe¡s of blue mackerel eggs taken by cruises, 1974-75                                           39

          48. Distribution of blue macke¡el eggs by cruises, I97,t-75 and t97 5-76                              +0

          49. Blue mackerel laruae                                                                              4l
          50. Numbers of blue mackerel larvae taken by cruises, 1974-75 and 1975-76                             +1

          51. Distribution of blue macke rel laruae by cruises, 1974-75 and 1975-76                             42

          52. Crested flounder eggs                                                                             +3

          53. Cumulative distriburion of crested flounder eggs, 1974-75                                         +3

          54. Crested flounder larvae                                                                           ++

          55. Distribution of crested flounder laruae by cruises, lg7+-75 and 1975-76                           +5

          56. Distribution of pleuronectid eggs by cruises, 197+-75 and 1975-76                           +G-47

          57. Numbers of pleuronectid eggs taken by cruises, lg7+-75 and 19?5-76                                +8

          58 Flounder lawa                                                                                      +8

          59. Cumulative distribution ol flounder laruae, 1974-75 znd 197:_76...                                48

          60. Numbers of flounder larvae raken by cruises, 1974-75 and 1975-76                                  49

          6l . Speckled sole larvae                                                                             49

          62. Cumulative distribution of speckled soìe larvae, lg74-75 and lg75-76                              50

          63. Numbers of speckled sole laruae taken by cruises, 1974-75 and 1975-76                             50
          64. Leather jacket eggs                                                                               50

          65. Numbers o{ leather jacket eggs within the study area, lg74-75 and 1975-76                         50

          66 Distribution      of leather jacket eggs by cruises, 1974-75 and 1975-76                     5   r-52
          67. Leather jacket larvae                                                                             53

          68. Cumulative distribution of leatherjacket lawae,1974-75 and 1975-76                                )+
          69. Unidentified egg I                                                                               54

          70. Unidentified egg 2                                                                               55

          71. Unidentified egg 3                                                                               55

          72. Numbers of eggs of all species taken by cruises, 1974-75 and 197i:-16                            57

          73. Monthly cumulative wind speed from obseruations at          Tiritiri Matangi Island              58

           I.    I(nds   of eggs and larvae collected in the   Hauraki Gulf   .   ..      .

           2. Spawning season and remperarures for the principal species in the Hauraki Gulf                   56

           3. Comparative eggproduction for 1974-75and 1975-76 ...                                             57

Inset I
175"E                                                       3ó"S


                                                                     Greot Borrier   I

    Omoho Boy

    .#--th*"wou     I
    ärr(                           Cope Colville
/                                                                                    30


     Rokino ,0 " .',


Fig. l:The Hauraki Gull, showing places mentioned in the text'

  The Hauraki Gulf, New Zealand's richest fishing               There are few published accounts of ichthyoplank-
ground, is a large, relatively shallow embayment with         ton surveys from New Zealand. In the Hauraki Gulf
many islands and harbours (Fig. l). It is an                  Cassie (t956a) studied the distribution of snapper
important spawning ground for many fish species,              eggs, and Colman (1973) studied the spawning of two
including snapper (Chrysophrys auratus), which domi-          species of flounder. Baker (1972) surveyed pilchard
nates the commercial landings. During the spring-             eggs and larvae in Tasman Bay, Robertson (ì980)
summer periods (October to January) oÍ 1974-75 and            recorded the distribution of the eggs of 17 species off
1975-76,2-weekly plankton surveys were carried out            the Otago coast, and Colman (1979) studied the
with the aim of estimating the stock size of snapper          spawning of the sprat around the South Island.
based on egg counts (Crossland 1980). These surveys           Additional information on the eggs and larvae of
were specifically designed for sampling snapper eggs;         species mentioned in this bulletin is given in Elder
however, many types of fish eggs and larvae were              (1966), Robertson and Raj (1971), Baker (1973),
collected, identified, and counted. These data are            Robertson (1973), Castle and RÒbertson (1974), and
presented  in this bulletin.                                  James (1976). Robertson's (1975) key describes the
                                                              planktonic eggs of 56 species of New Zealand fishes.

                                MATERIAL AND METHODS

            SAMPLING AND SORTING                              and larvae and sorted them according to type. When
                                                              the sorters were sufficiently experienced to identify the
    Plankton samples were taken by oblique tows of a
                      at the stations shown in Fig. 2.        different kinds accurately, the common ones were
cylinder-cone net
                                                              counted in situ in the samples. Regular checks were
Details of the net were: mouth area0.25 m2; cylinder
                                                              made on the accuracy of identifications and sample
56 cm diameter by 150 cm long; cone slope length
                                                              counts. Large samples were divided with a Folsom
185 cm; gauze 0.425-mm aperture with a porosity of
                                                              splitter until a manageable fraction was obtained. In
47"/.. Ttie total filtering area was 2.225 m2 and the
                                                              samples where eggs were abundant but larvae were
filtering'area/mouth area ratio was 8.9, made up of
                                                              not, eggs were subsampled, and the whole sample was
5.35 in the cylinder a¡rd 3.55 in the cone. The volume
                                                              sorted for larvae. Details of the dates of sampling,
of water sampled (range 50-300 m3) was recorded               numbers of stations, ancl sea temperature data and
with a digital flow meter, type 2030 by     General
                                                              further information on the sampling technique can be
Oceanics, Inc., which was mounted at a distance of a
                                                              found in Crossland (1980).
quarter the diameter from the rim of the net. Tows
were made at a boat speed of 2 to 2.5 knots, with the
net usually descending to within 2 to 4 m of the               IDENTIFICATION OF EGGS AND LARVAE
bottom.                                                         Robertson's (1975) key was useful in identifying
   Samples were preserved in 5y" neutralised                  many of the eggs. Other eggs and larvae were
formalin. During sorting all fish eggs and larvae were        identified by building up a series of developmental
counted. Initially plankton sorters removed all eggs          stages from egg to larva to recognisable juvenile.

.40     ll.          42.

                                                                                  33.   34.    35.    36.    37.   38.   39.
 28.          26.          25.

                                                        21. zlA!
i'frãJ iot          ''.
      ì5.     14.         13.

                                       Fig   2: Suruey stations and study area.   Left: 1974-75. Right: 1975-76.

Larvae of some species were identified by their                                            DATA PRESENTATION
similarity to those of related species which had been                           This study was made on a more intensive scale
described from other parts of the world. Electrophor-                         (that is, at shorter time intervals and with stations
etic tissue analysis aided in identifying snapper larvae                      closer together) than is common with ichthyoplankton
(Smith and Crossland 1977) and larvae of the spotted                          surveys.     The complete data, which are held in
stargazer. The distribution and abundance of species                          Fisheries Research Division library, give the counts
occurring locally as adults were also considered.                             recorded for each type of egg and larva for every
                                                                              sample taken; these were calculated as numbers per
   DESCRIPTIONS OF EGGS AND LARVAE                                            100 m3 (eggs) and numbers per 500 m3 (larvae).
   This bu-letin describes and illustrates eggs and                             !'or some of the more common egg types the
Iarvae taken or refers to published accounts.
                                                                              densities were integrated over the study area to give
   The descriptions of larvae are intended to highlight                       estimates of the total numbers present at one time on
features which will allow recognition of the individual                       that cruise. This was done by multiplying each
species; they are not meant to be detailed, stage-by-                         individual station volume (station area by mean
stage descriptions of larval growth and morphology.                           depth) by its egg density and then summing over the
Most species can readily be distinguished. Exceptions                         whole study area. The calculations were adjusted for
are the two species of. Rhombosole¿ and the two species                       the slight variation in area between the 2 years. The
of. Trachurus, all of which may be present in the                             method of integration is explained fully in Crossland
sampling area.                                                                (1980) . The embryonic period was not known for any
  A1l descriptions and measurements apFly to                                  of the eggs; so it was not possible to calculate total egg
material which was preserved in 5"/" neutralised                              production.
formalin. Measurements were made under a stereo                                   Distribution maps were plotted               for the more
microscope at a magnification of 62 x. The length                             common tyPes of eggs and larvae as numbers below
recorded {or larvae was total length. The figures o{                          l0 m2. Cruises not shown in the map series recorded
eggs and larvae were also made by use of a stereo                             fewer eggs and larvae than the minimum contour level
 microscope and a drawing tube.                                               for that     species.


   Both fish eggs and larvae were very abundant in the                    immediately recognisable, as the only other species
Hauraki Gulf.   In 1974-75 the 330 samples contained                      known from New Zealand to have an elliptical egg,
583 000 eggs and 55 000 larvae. In 1975-76, 589 000                       the carapid Echiodon sp., cloes not occur in the Hauraki
eggs and 79 000 larvae were collected in 426 samples.                     Gulf.
The maximum number of eggs taken in one haul was
89 000, and that of larvae was 6000. For both years
combined, only 2 samples contained no eggs, and 2l                          The distribution of anchovy eggs for the 2 years
contained no larvae. The kinds of cggs and larvae                         (Fig. 3) showed a spawrring centre within the study
recognised are shown in Table l. Details of the                           area. Anchovy eggs were common and occurred on all
distribution, seasonality, and abundance for eggs and                     cruises in both years. During October spawning was
larvae of each species are given below. The species                       light and took place in the southern part of the gulf
have been placed in phylogenetic sequence according                       near Waiheke Island and the northern part of the
to Nelson (1976).                                                         Firth of Thames. The main burst of spawning
                                                                          observed was during November in 1974, and
                                                                          December in 1975. The centre of spawning moved
  The relationship between spawning and tempera-                          north to the central gulf-Kawau Island area as the
ture was also considered. For demersal species (for                       season progressed, a similar pattern to that observed
example, flounder or gurnard) the sea bottom                              for snapper (Crossland 1980). Spawning was still
temperature was used; for pelagic species (for                            taking place at the end o{ the sampling period in each
example, anchovy or pilchard) the sea surface                             year.
temperature; and for species occurring throughout the
water column (for example, jack mackerel or ahuru)
the mean of bottom and surface temperatures.                                 The relationship betw,een temperature and spawn-
                                                                          ing (Fig. 4) showed that spawning began when rhe sea
                                                                          surface temperature was about l6"c and was most
                                                                          intense at l9o-20"c. The number of eggs produced in
Family Engraulidae                                                        the 1975-76 study period was about three times that
                                                                          of the previous year (Fig. 4). These figures have been
Anchory        Engraulis australis (White, I790)                          integrated over the stucly area, but not over time,
 Eggs. The anchor,y egg is described and {igured in                       because the embryonic period of the anchovy is not
Robertson (1975). Its elliptical shape makes it                           known. Crude egg counts do not consider the effect of

        TABLE l: Kinds of eggs and larvae collected in the Hauraki Gulf, October to January in 197Ç75 and 1975-76
                       Species                       Egg.   Lawae                             Species              Egg.      Lawae
 Anchorry (Engrailis australi)                        I      +           Snapper (Chrysoþhrys  auratus)             +         +
 Pilchard (Sardinops neopilchardus)                   +      +           Yellow-eyed mullet (Aldrichetta forster)   +         +
 Sprat (Sprattus ant;þodum)                           +      -l          Grey mullet (Mugil cephalus)               -         +
 Moray eel Family Muraenidae                          +      +           Spotty (Pseudolabrus celidotus)            -         +
 Sand eel Gtathophis sp.                              +                  Spotted stargazer (Gcnyagnu monoþterygius) +         +
 Alauru (Auchmoccros
                                                     l       +
                                                                         Blennies: Family Blenniidae, Family Clinidae,
                                                                           Family Tripterygiidae
                                                                         Graham's gudgeon (Grahamíihthys radiatus)
John                      as)                                +           Bar¡acouta (Tþrsítes atun)                           +
Seaho¡se (Hippocampus abdominalis)                           +           Blue mackerel (Scomber australasicus)           +    +
Long-snouted pipefish (Stigmatoþhora longiros tns)           +           Crested flounde¡ (Lophonectes gallus)           +    +
                                                                         Flounder Rhombosolea þIebcía &. R. leporina     +    +
Red gurnard (Chelídonichthys kunu)
Rockfish Acanthoclinus quadridacllus                 I       +
                                                             +           Speckled sole (Peltorhamþhus latw)              +
Rockfish A. trilin¿atus                                      +           Leather jac*.et (Nooodon coruexirostris)             +
Jack mackerel Trachurus noaa¿z¿landiae               +       +           Porcupine   Tts}:, Allomycterus   jaatlifents        +
Jack nackerel T. decliais                            +                   Three unidentified species                      +
+ Present.
t   Absent.

4-8 Nov

                                          ó-'l0 Jon   1975

                     5000- >t0 000
                     r0 000
            No. below l0   m2             Fig. 3 (above and right): Distribution of anchovy eggs by cruises, 1974-75 and 1975-76.

temperature on development. The egg production                    larvae were in the central and outer gulf, further north
shown in Fig. 4 has been adjusted on the basis that the           than the eggs. Large numbers of larvae occurred on
development period is halved for a l0oç rise in                   the November cruises in 1974, when the numbers of
temperature. This effect was found experimentally for             eggs were low. This probably resulted from bursts of
snapper eggs {rom the Hauraki Gulf (Cassie 1956b).                spawning which took place between sampling cruiscs
                                                                  and were thus not sampled, and it showed that even
   Larvae. The anchovy larva is described and figured             sampling at 2-weekly intervals may be insufficient to
in Baker (t972). It may readily be distinguished from             measure the egg production of the mobile, shoaling
larvae of the other lttrew Zealand clupeoids pilchard             ancholy.
(Sardinoþs neoþilchardus) and sprat (Spratns antipodum)
by its underslung jaw and the relative positions of its
anal and dorsal fins, which overlap. The latter feature
is particularly useful for identification, even in small
larvae.                                                           Family Clupeidae
                                                                  Pilchard    Sardinoþs neoþilchardus   (Steindachner, IB79)

   The distribution of anchovy larvae (Fig.'5) differed             Eggs. The development of the pilchard egg is
from that of the eggs. The main concentrations of                 described and Iigured in Baker (1972). These eggs

I   Z-21 Nov   1975                      I   -5   Dec 1975                                 15   -]9   Dec ]975

  29 -31 Dec 1975
                                               12-16 )on197ó
                                                                                             27 -3Q Jon 1976

rvere present from the beginning of sampling in each                                                                                  24
year (October) until mid November in 1974 and mid
I)ecember in 1975. They were seldom abundant, and                                                                                     22
on only one cruise (,1.-B November 1974) was there a
large spawning within the study area (Fig. 6).                                                                                        20^

   Larvae. The pilchard larva is described and figured                                                                                l8   c¡
in Baker (1972). Small pilchard larvae are difficult to
distinguish from larvae of the sprat Sþrattus antiþodum.
Larvae longer than about 25 mm can be identified by                                                                                        o
the differences noted by Baker. Pilchard larvae have a              Ic                                                                     o
                                                                     ,(                                                                    o
melanophore below the eye and one at the base of the
pelvic fin, and the last ray in the anal fin is elongated.          o)
                                                                    CJ                                                                     o
These features are absent in sprat larvae. During this              o                                                                 203
study all clupeid larvae large enough to be identified              c)

were pilchard; smaller larvae of the same type were,                -o
therefore, assumed to be pilchard also. Some error                  zf
may be introduced by this, but since pilchard is very
common in the Hauraki Gulf and sprat uncommon,
the error will be small.                                                         1529 122ó1024721                                 4
                                                                                            Nov           Dec        Jon         Feb

                                                                     Fig.4: Number of ancholy eggs within the study area at the
  The distribution of larvae in both years (Fig. 7)                       time of sampling for each cruise, 197 Ç-7 5 and 1975-76. Mean
showed that the main spawning areas of the pilchard                       sea surface temperatu¡es for each cruise are also shown.

2- ó Dec          1974

                                                                                                                                    0    r-.
                                                                                                                                         i)     â
                                                                              \uu4    0
                                                                 //\  r^\^ .lV

6   -9 Oct 1975                                            lZ-20 Nov      ì975                                    l-4     Dec 1975

                                                                                                                         h-l             / ¿¡
                                                                                                                                         r !:u   _-ì
                                                                                                                               ./       | --   /     t

                        s----:--                \-?'


    fiQ s
            -   -                           -


                      il  rsJ
                    ^ r,4lJ,4                                  ov"Ëfd^L                                                         J çz-¿r,t¿)
                                                                                                                         *j. "'"q¡"J¿
                    /\.c>                              !         /\¡^..- ü                                                 As>
ló - 19 Dec                        1975

                                                                                             rLiii   ll|illiill

                                                                                      50-200 200-500              500-         >looo

                                                                                             No. below ìO m'

                                                            Fig. 5: Distribution of anchory larvae by cruises, 197'l-75 and 1975-76.
    27 -3O Jon1976
took place outside the study area; however, the sea
                                                                    surface temperatures at the outer stations were in the
                                                                    range 16.lo-17.8"c at the peak occurrence of larvae.

                                                                    Sprat      Sþrattus antipodum    (Hector,   1872)
                                                                      Eggs. The sprat egg is described and figured in
                                                                    Baker (1973). These eggs were taken in only small
                                                                    numbers and occurred sporadically in time and space.
                                                                    Their cumulative distributions for the 2 years are
                                                                    shown in Fig. 9. The largest patch of eggs was found
                                                                    in late October 1975, off Kauri Point, Waiheke

                                                                       Larvae. Sprat larvae were not recognised in any
                                                                    sample, but they may have been confused with small
                                                                    (less than 25 mm) pilchard larvae.

                                                                      Adult sprat are occasionally taken by bottom trawl
  4- 8 Nov 1924                                                     in the Hauraki Gulf if a cod-end liner is fitted, but
                                                                    they do not appear to be abundant. Baker (1973)
                                                                    recorded sprat spawning in the Marlborough Sounds
                                                                    from July to January. Robertson (I980), sampling off
                                                                    the Otago coast, found that spawning lasted from
                                                                    May to November and peaked in June-August. In the
     500-          2000-           5000-        >10 000             Hauraki Gulf the sampling period was outside the
      2000          5000          r0 000                            main spawning season found by these workers.
                                                                    However, it is unlikely that major spawning took
                    No. below lO m2                                 place in the winters oÍ 1974 and 1975, because sprar
                                                                    larvae or juveniles would have been recognised in the
   Fig. 6: Distribution of pilchard eggs, 4-B Novembe¡ 1974.        samples.

were north of the study area, probably in the Jellicoe
and Cradock Channels. The numbers of larvae taken
in each cruise are shown in Fig. 8. A similar pattern
was apparent in both years, but the peak lagged by 2
                                                                    Family Muraenidae
weeks in 1975-76, when temperatures were lower.
Larval numbers reached a maximum in the first week                  Morayeel        (unidentified)
of November in 1974, and in the third week in 1975.                   Eel eggs and larvae of a previously undescribed
Peak spawning would therefore have taken place                      type were occasionally taken in the outer stations of
earlier, possibly in late October or early November.                the study area. Because of their close similarity to the
                                                                    eggs and larvae of moray eels from European waters
                                                                    (see Sparta 1939), they were identified as one of the
  These results can be compared with those of Baker                 species of morays found in New Zealand. The most
(1972), who studied a population in Tasman Bay and                  commonly observed species locally is the yellow
found the breeding season to be lrTovember to                       moray (Llcodontis þrasinus (Richardson, 1847)).
February, with a peak in December-January; that is,
some 6 weeks to 2 months later than in the Hauraki
Gulf . The difference in latitude between Tasman Bay                  Eggs. These eggs hadi a diameter of 3.9-4.5 mm; a
(41" S) and the Hauraki Gulf (36' 30' S) is the                     wide perivitelline space (especially in early stages);
probable reason for this. Baker found that most                     and a finely segmented yolk with 6 to 40 oil droplets,
pilchard eggs were spawned when the sea surface                     0.07-0.15 mm in diameler (Fig. l0). Eggs were first
temperature was between 16.0' and l6.4oc It was                     observed in mid December and were still present at
difficult to make a direct comparison with tempera-                 the end of the sampling period in late January. The
ture data from this study, because most spawning                    cumulative egg distribution for 1974-75 is shown in

â\\,   -*_  _/--\\            sÈ{il!,
     õJ      ._--_-r                'r._____


21   -25 Oct       197Á.                                                                 l8 - 22 Nov        1974

                                                      al (_----
                                                         .-'-/'-l     i.

                                                       l')Ä>          ,y
                                               16 -   20 Dec   1974

              \\\\         i
           ..'      z-:        ,/

                                                                                                   )\                 a
      t)v>                                                                                      f-'>\.l r,'-'t?)
                   l,â.2_. \
                       *!yrÌ "                                                                          t¡ê,.i
      -1N                                                                                         ](\ xuy4¡

         //\ r\^ \l                                                                               /lÄ>                ,v

ó   -9 Oct    ì975                              20 - 23 Oct 1975                         3-7Nov1975

                                                                                                    't''l          q"rn   ,;


      /-\ ^L/ d   .rJ
      \JVÞ 1,¡¿7e,-,.1          o
         \l\          )
         2\ ñ
         /À¡\Þ"v           \) I

lZ- 20 Novì                                                                              ló - 19 Dec        1975

                                                                      50-200 200-500500-          >1000

                                                                               No   below lO m'

                                                      Fig. 7: Distribution of pilchard larvae by cruises,1974-75 and 1975-76.
Fig. ll. Spawning appeared to be located mainly
                                                         outside the study area, probably over the rocky
                                                         bottom around Great and Little Barrier: Islands, a
                                                         habitat favoured by morays. Fewer eggs were taken in
                                                         1975-76 because the outer part of the Hauraki Gulf
o                                                        was not sampled.
o                                                          Larvae. Five larvae were taken in 1974-75 and two
o                                                        in 1975-76; they were found close to the eggs. They
o                                                        were immediately recognisable by their long, slender
                                                         shape and fearsome array of íorward-pointing teeth
                                  1975-76                (Fig. I2).

      lrs29   1226 1024721                    4          Fig.8: Numbers of pilchard la¡vae taken by cruises, I974-75
     Ocl      Nov   Dec         Jon          Feb           and 1975-76

                                                                                         5-20      20-50      50 - 100
                                                                                               No. below l0      m2

                                                                                       Fig. 9: Cumulative distribution
                                                                                         of sprat eggs. Left: 1974-75
                                                                                         Right: 1975-76.


                          Fig. l0: Moray eel eggs

Family Moridae
                                                                                             Ahuru                        (Hutton, 1873)
                                                                                                        Auchenoceros punctatus
                                                                                               Eggs. The ahuru egg is described and figured in
                                                                                             Robertson (1975). The distribution of ahuru eggs for
                                                                                             the 2 years is shown in Fig. 13. The centre of
                                                                                             spawning was in the northern part of the Firth of
                                                                                             Thames. Figure 14 shows seasonal changes in egg
                                                                                             numbers for the 2 years and the mean sea
                                                                                             temperatures in the spawning area. Few eggs were
                                                                                             observed in 1974, but they were common during
                                                                                             October and November 1975, when sea temperatures
                                                                                             were lower than in the previous year. These findings
                                                                                             are consistent with those of Robertson (1980), who
                                                                                             found that in Otago waters ahuru were winter-spring
                                                                                             spawners, preferring cool, Iow-salinity, in-shore

                                                                                                Larvae. The. main distinguishing features of the
                                                                                             larvae are the large numbers of rays in the dorsal and
                                                                                             anal fins, and in older larvae the single hair-like ray in
                                                                                             front of the dorsal fin (Fig. 15). Small larvae have no
                                                                                             particularly distinctive features and were recognised
                                                                                             after building up a developmental series.

                                                                                               Ahuru larvae were common in the study area and
                                                   ...........Jir¡¡¡;                        were more abundant than the eggs, particularly in the
                             r     -5
                                 5-20                                                        first year.In 1974-75,6800 were recorded, and in
                                                                                             1975-76, 9700. They were most numerous during
                        No. below lO m2                                                      October and Nlovember (Fig. l6), with a marked peak
 Fig.   ll:   Cumulative dist¡ibution of moray eel eggs, Ig?4-75
                                                                                             in November 1975, 2 weeks after the peak in egg
                                                                                             numbers. The relatively high numbers of larvae and
                                                                                             low numbers of eggs in 197+-75 indicated that
                                                                                             spawning either took place mainly outside the study
                                                                                             area (to the south) or before sampling began.
Family Congridae
Sand eel Gnathophis incognitus Castle, 1963 or                                    G.           The distribution of larvae (Fig. l7) shows distinct
habenatus      (Richardson, I848)                                                            and puzzling differences from that of the eggs. In both
   Eggs. The egg of Gnathoþhis sp. is described and                                          years few larvae were found in the immediate vicinity
{igured in Castle and Robertson (1974) . Five eggs of                                        of spawning. In 1974-75 larvae were commonest in
this type were taken in one sample on 22 January                                             the eastern gulf, off the Coromandel Peninsula. In
1975; two were at the early blastodisc stage and three                                       1975-76 they were found both there and more widely
had well-developed embryos.                                                                  spread over the central gulf.

                                                                        Fig. 12: Moray eel Larva (9.6 mnr).

4-8 Nov 1974

 ó - l0 Oct 1975                         20    -24 Oct   1975                          3   -7   lNov 1975

                                                                                       50-200 200-500 500-            > r000
                                                                                                    No. below lO m'

              ,l975                            -5   Dec 1975
  l7-21 Nov                                1

                           Fig. 13: Distribution of ahuru eggs by cruises, 197'[-75 and 1975-76

   A possible expianation for the disjunctive egg and '              and the smallest larvae taken were about 4 mm long.
larval distributions is that the larvae were carried by              Flowever, ahuru juveniles, some up to 45 mm long,
water movements from the spawning area and were                      were sometimes tallen and were the                  largest
not sampled until they reached a size large enough to                ichthyoplankton caught during this survey. Adults
be retaiñed by the plankton net. The newly hatched                   seldom exceed 120 mm and are susPected to live off
larva from the small ahuru egg (0.525-O.600 mm                       the bottom. Graham (1956) found that ahuru fed
diameter) is unlikely to exceed 1.5 mm total length                  principally on a surface-living copepod.

Family Exocoetidae
Garfish Hyþorhamþhus zår Phillips , Ig32
  The early development of the garfish is described
and figured in Graham (1956). This species has
adhesive, demersal eggs.
                                                                            I                                                      róã
                                                                                                                                   r; 9
  Larvae. Two larvae (measuring 10.6 and I 1.0 mm)                 þo
                                                                       x                                                                  o_
were taken in 1975, and one (meâsuring ll.3 mm) in                                                                                        E

1976. In both years they were taken in the northern                    $r                                                          20P
                                                                       o                                                                  o
central gulf in late January. The heaviiy pigmenred                    o2                                                                 c,

garfish larva is distinctive (Fig. IB), with a prominent
                                                                       o                                                                  o
                                                                   !                                                                      o
double row of rouncl pigment spots along its back.                 5r                                                              ló=
The lower jaw projects beyond the upper.                           z
                                                                           0                                                       14
                                                                                I     1529122610247214
Family Trachichthyidae                                                     Oct              Nov   Dec                Jon        Feb

Roughy (unidentified)                                                      Fig. 14: Numbers of ahuru eggs taken by cruises, 1974-75 and
                                                                             1975-76. Mean sea temperatures in the spawning area are
  Larvae. During December and January, larvae                                   also shown.
(Fig. I9) identified to this farnily were taken
occasionally at the outer stations of the study area.

                                 Fig. 15: Ahuru (Auchnoceros þunctatus) larvae (5.6, 12.8 mm).

single juvenile   ll.9   mmL lÒng was taken     in the outer
                                                                             gulf on 16 January        1976.

                                                                             Family Syngnathidae
'o                                                                             Small juveniles of the seahorse (Hippocampus
 x                                                                           abdominalis Lesson, l8l8) and the long-snouted
o                                                                            pipefish (Stigmatoþhora longirostris llutton, I 8 72) were
       5                                             197s-76                 occasionally recorded.
o 4

E                                                                            Family Triglidae
z                                                                            Red   gurnard     Chelidonichthys kumu (Lesson and
                                                                             Garnot, l826)
                                                                                Eggs. The red gurnard egg is described and figured
                                                                             in Mito  (1963) and Robertson (1975). Red gurnard
                                                                             eggs were taken on every cruise during both years, but
                             12                     721                      were never abundant. The cumulative egg distribu-
           l15                     26                            1
                                                                             tion was remarkably similar in both years (Fig. 20)
       Oct                   Nov        Dec         Jú           Feb
                                                                             and showed the main spawning centre to be at the
      Fig. 16: Numbers of ahuru larvae taken by cruises, 1974-75 and         northern edge of the study area or still further to the
                                                                             north. The seasonal variation in egg numbers for
                                                                             197+-75 indicated         a spring        spawning peak in
They may have been larvae of the slender roughy                              October, but in 1975-76 peak egg numbers occurred
(Optiaus elongatus, (Günther, 1859)), the most common                        in December (Fig. 2t). However, in both years the sea
species of roughy observed by divers along rocky                             bottom temperatures in the spawning area were
coastlines in northern New Zealand (Doak 1972).                              similar at peak spawning (15.6'c in 1974-75 and
Most larvae were small (3.5-4.5 mm long). The                                15.7'c in 1975-76). Ekler (1976) considered that the
Iargest was 8.3 mm and the skin on the dorsal surface                        time of peak spawning was influenced by temPera-
of its head and body was covered with tiny spines.                           ture, through its effect on the maturation rate of the

Family Zeidae
John          Dory    Zeas japonicas    (Richardson, IB45)                      Larvae. Early stages of the red gurnard larva are
       The eggs of this species have'been    described                       figured in Mito (1963) . The cumulative distrit¡utions
 (Robertson 1975), but were not taken in this study. A                       of larvae (Fig. 22) showed a pattern of dispersal

                  æ   1971                                                                        l8 -22 Nov   1974

                               Fig. 17: Distribution of ahuru lawae by cruises, 1974-75 (see key on following page).

{t z-ì                        /
                                                )r-s.--      -----**
                                                                              \         z

                                                                                                                 )\             lL
                                                    al\/^/L ¡r^^.-.t"!
                                                                                                            z---r\    / cr,-a r:J
                                                    ^--"-"                        o
                                                                                                             /J\ * t'\
                                                      //\ r^r^ V
                                                       \t\                   -J   I
                                                                                                               l/ ì.\ Y
6-9   Oct1975                              20 - 23 Oct           1975                                 3   -Z   Nov     1975

                                                                                                            20-s0 s0-200 200-500
                                                                                                                      No. below l0 m2

l7 -20 Nov   1975                          1   -4   Dec 1975

                            Fig l7   (continued): Distribution of ahuru larvae by cruises, 1975-76.

                                                                              southwards from the spawning area; this was more
                                                                              marked ín 1974-75, perhaps because spawning began
                                                                              earlier that year (see Fig. 2l). These findings concur
                                                                              with those of Elder (1976), who postulated that larvae
                                                                              drifted south a{ter â northward, contranatant
                                                                              migration of adult red gurnard from the inner
                                                                              Hauraki Gulf to a spawning ground in the Cradock
  Fig. 18: GarÍish (Hyþorhamþhus ih) larua (1t.3 mm).                         and Colville Channels.

                                                                              Family Acanthoclinidae
                                                                              Rockfish Acanthoclinus quadridactylus (Bloch and
                                                                              Schneider, l80l) and A. trilineatus (Griffin, 1933)
                                                                                      Jillett (1968) described the early life history of A.
                                                                                  quadridactylus, a small littoral fish which lays demersal
                                                                                  eggs. The adults of both A. quadridactylus and A.
                                                                                  trilineatus are described and figured in Griffin (1933).

                                                                              Fig.    19: Roughy (Family Trachichthyidae)      larva (5.3 mm).

r-5       5-20       >20
                                                                                                                           below l0   m2

             î,1      ffi
                               Fig' 20: cumulative disrriburion or red gurnard eggs Lefr: rg74-75.
                                                                                                   Righr: 1975-76

                                                                                                                                          ló U
                                                                                       o                                                        o
                                                                                       E                                                       o
                                                                                       l                                                       o-
                                                                                       z    r50                                                E
                                                                                                                            1975-76            o
                                                                                            100                                           r8 o
                                                                                                                                          tó o
     Fig.   2.1:         of red gurnard eggs taken by cruises, lg74-75
          and 1975-76. Mean sea bottom temperaturés in the Ápawning
          area are also shown.
                                                                                                  rt5   1226t024721                   4

                                                                                             Oct        Nov     Dec        Jon        Feb

                                                                                                          r-5    5   -r0    r0-20     >20
                                                                                                                 No. below lO m2

                                                               \   '\   sï?/!-/-{-\,

                             Fig.22: Cumulative distribution of red gurnard larvae. Left: 1,974-75. Right: 1975-76


Inset 3
Larvae. Small larvae oÍ A. quadridacQlus up to                        Family Carangidae
5.5 mm long are figured in Jillett (1968) . Lawae of the                  There are two species oÍ Trachurus (jack mackerel)
two species were not recorded separately during this                    found    in New Zealand waters (Stephenson and
study. The illustrated specimen (Fig. 23) is A'                         Robertson 1977). Trachurus nouaezelandiae is abundant
trilineatus, which has more dorsal and anal fin rays                    in in-shore waters in northern New Zealand. Trachurus
than A. quadridactllus and a more slender body. The                     decliuis usually lives further off shore and is found
larvae are heavily pigmented with dark brown sPots'                     throughout New Zealand. The eggs of both species
                                                                        are described in Robertson (1975), but this study and
                                                                        recent findings    of    Robertson (pers. comm.) have
  'l'he cumulative distribution for the 2              years            shown these descriptions to be inaccurate.
(Fig. 2a) showed the larvae to be well dispersed' but
with the largest numbers usually recorded close to                                                                           (Richardson,
land. Larvae were collected on all cruises in both                      Jack mackerel Trachurus           noaaezelandiae
years, except the làst cruise in 1974-75. Their
numbers declined steadily as the sea temPerature                          Eggs. The eggs of T.        nouaezelandiae    (:    T. mccullochl
increased. More larvae were collected in 1975-76 than                   are described in Robertson (1975) as having                           a
in the previous year, which was warmer. These results                   diameter of 0.720-0.820 mm, a segmented yolk, and a
are consistent with Jillett's findings that                  A.         single oil droplet. During this study eggs conforming
               winter spawner, with peak spawning
quadridacQlus is a                                                      to this description were not taken, but an egg slightly
in September and October. (Jillett considered Sep-                      Iarger than this was regularly caught and was very
tember and October as winter.)                                          abundant. The likely causes of this size discrepancy

                                                                                                Fig. 23: Rockfish Acanlhoclinus trilin¿alus
                                                                                                  Iarva (10.0 mm).

                                                           â\* -- ------._,t
                                                             n(                                                                     10 m2

                                                               \-v1.       \

                                                                  \i      ,'

                         Fig   24: Cumularive distribution   of rockfish laruae LeÍv 1974-75. Right: 1975-76.

are that Robertson's measurements were of unfertil-                                 The egg distribution (Fig. 26) showed the Hauraki
    ised eggs which were probably not fully mature, and                            Gulf to be an important spawning area Íor                 T.
    that a slight     increase    in   size normally occurs at                     nouae4landiae. Most sparvning occurred in the western
    fertilisation.                                                                 side of the gulf, a few rniles off shore, and in depths
                                                                                   greater than 30 m. Spawning extended from Rakino
  The eggs shown in Fig. 25 had a diameter of 0.78-                                Island in the south to Cape Rodney in the north, with
0.88 mm; a narrow perivitelline space; a segmented                                 the densest patches of eggs east of Tiritiri Matangi
yolk (segmentation irregular and not always distinct,                              and Kawau Islands, the areas in which snapper eggs
in the early stages more noticeable just below the                                 were also most abundant (Crossland 1980). In 1974-
blastodisc) (see Fig. 25 top); and a single, yellowish                             75 there was another important spawning area off the
oil droplet,         0.204.27 rnrn      in     diameter, situated                  south-west shore of Great Barrier Island; this part of
anteriorly in late stage eggs. The embryo was stout                                the gulf was not sampled in t975-76.
bodied with numerous prominent melanophores
along the dorsal surface.
                                                                                        The seasonal changes in egg production are shown
  These eggs were considered to be those                            of   T.        in Fig. 27. TÌr'e figures have been adjusted for
nouae4landiae for the following reasons:
                                                                                   temperature effect (as described for anchovy eggs)
                                                                                   and the numbers in the .t974-75 season are for a;trarea
   They had the typical carangid egg features of
                                                                                   equivalent to that sampled in 1975-76. The observed
segmented yolk; single, anterior oil droplet; and
                                                                                   egg production was similar in both years. peak
relatively undeveloped embryo at hatching.
                                                                                   spawning occurred in nrid November in 1g74, when
2. An embryological series was built up and the late                               the mean sea temperature was 17.3"c, and in mid
                                                                                   December in 1975 at a mean sea temperature of l7.9oc.
stage embryos were indistinguishable from yolk-sac
larvae of T. nouaelelandiae.

3; Measurements          of   100 unfertilised eggs from a ripe                      Larvae. The larvae      of. T. nouae¿elandiae (Fig. 28) are
specimen         of T.          gave the following
                          nouaezelandiae                                           similar to those of. T.   symmetreczs (Ahlstrom and Ball
results:.diameter 0.775-0.865 mm (mean 0.825 mm);                                  1954) from the north-eastern Pacific. They show the
oil droplet           0.191-0.250      mm diameter              (mean              distinctive carangid feature of three rows                 of
0.226       mm) (Robertson pers. comm.).                                           melanophores on each side, one each along the dorsal
                                                                                   and ventral margins of the body and one along the
4. The eggs are not those of trevally (Caranx georgianus                           lateral line. They can readily be distinguished lrom
(Cuvier, 1833)), another carangid known to occur in                                the larvae of trevally because the latter are more
the Hauraki Gulf. Although of a similar size, the                                  dlkly pigmented and have a deeper body (James
trevally egg has an unpigmented embryo                         (James
                                                                                   r   s76).
r   e76).
                                                                                     The distribution of larvae (Fig. 29) was similar for
                                                                                   both years. Larvae were found close to the eggs for the
                                                                                   corresponding period, but were displaced a few miles
                                                                                   to the north-east, further into the central gulf. Larval
                                                                                   numbers (FiS. 30) showed            a distinct peak       in
                                                                                   November of each year. In 1974 this coincided with
                                                                                   the peak in egg numbers, but in 1975 it occurred a
                                                                                   month before the egg peak. This could be the result of
                                                                                   a large spawning     inside the study area between
                                                                                   sampling periods, or it could have resulted from a
                                                                                   spawning to the north of the study area, with the
                                                                                   larvae carried south lty currents (compare with
                                                                                   pilchard and gurnard).

                                                                                   Jack mackerel Trachurus decliais (Jenyns,        1841)
                                                                                      Eggs. Robertson's (1975) description gives the egg
                                                                                   diameter as l.l-1.3 mm. This was based on a poorly
                                                                                   preserved sample and is inaccurate. A more recent
          Fig. 25: Jack macke¡el Trachurus   nouac¿clandiae eggs.                  sample of 100 artificially fertilised eggs had a diameter

4-8 Nov 1974

                                                  20-23 Jo¡1975


      l\     r^.,^   tl
20-24 Oc¡    1975         3   -Z Nov 1975

 I -5 Dec l9Z5            l5 -19   Dec 1975       29 - 31 De< 1975

                                                  500- 2000- 5000-           >t0000
                                                  2000 5000 10000
                                                           No. below l0 m'

                                                  Fie.                of       jack
                                                   - 26: Distribution
                                                       mackerel T. noaaez¿Iandia¿
                                                       eggs bY cruises, 1974-75
                                                       and 1975-76.
                              27 -3O )on   1976
range of 0.970-1.030 mm (mean 0.998 mm) and            a
                                                                                segmented yolk with an oil droplet of 0.238-0.302 mm
                                                                                (mean 0.266 mm) diameter (Robertson pers. comm.).
                                                                                Eggs conforming to this description were occasionally
                                                                                recorded in the Hauraki Gulf. They ranged in size

                                                                                from 0.95 to 1.02 mm diameter and had an oil droplet
                                                                                of 0.23-0.29 mm diameter. The late stage embryo was
                                                                lói             more slender and muc.h more lightly pigmented than
 x                                                                    o
                                                                                that of T. nouae4landiae (Fig. 3l). Cumulative       egg
                                                                      o         distributions for the 2 years are shown in Fig.      32.
 o                                                                    E

 {J                                                                               Larvae. The larvae oÍ T. decliuis are probably so
-o                                                                    c
)E                                                                              similar to those of. T. nouaelelandiae that separation of
z                                                               'rg             the two species may only be possible by biochemical
                                                                                means. Stephenson and Robertson (t977) could not
                                                                                distinguish juveniles of the two species if they were
                                                                                shorter than 35 mm standard length. Because the eggs
                                                                                oL T. decliuis were only rarely recorded, and nearly all
                                                                                adult jack mackerel observed in the Hauraki Gulf are
       11529               1226 1024721                     4                   T. nouae4landiae, all Trachurus lar.'ae were assumed to
      Oct                  Nov  Dec   Jon                  Feb
                                                                                be T.   nooaelelandiae.

  Fig. 27: Number of jack mackerel T. noraezelandiaø eggs within
    the study area at the tirre of sampling for each cruise, 197.f-
     75 and 1975-76. Mean sea tempe¡atu¡es for each cruise a¡e
    also shown.

      Fig. 28: Jack mackerel      Trachums   noaa¿-
        zelandiae   larvae (4.4, 7.6, 8.9 mm).

                                                                                                                              ^ tz'-.-¡")
                                                                                                                                o u4-4t.9
21 -   25 Oct                1974                                                                                   18   -22 Nov   1974

        //\ r^\^ V



                                                                                    50-200 200-500                  500-    >t000
                              \t                                                                                    t000
                                                                                           No. below lO m'1


        i,Effi                                         Fig. 29: Distribution of jack mackerel T. noaae4landiaelarvaeby
 2Q-23 Jon1975                                              cruises, 197,S-75 and 1975-76.

                  /\                     L
        /-\/ d
        !)v* l,rÞ- -J \
                -ê^41ì/'¿                    .

               \t\                       )     I

       aJi                                         I
                                                                                    Fig.   3l: Eggs of jack mackerel Trachwas      decliuis.

                                                                               Larvae. The early stage larva uP to a length of
                                                                             3.2 mm is described and figured in Cassie (1956b)                       .

                                                                             The patches of yellow pigment he observed in living
      11529           1226 1024721                                 4
                                                                             specimens were not aPParent in preserved samples,
     Oct             Nov   Dec  Jon                               Feb
                                                                             and the absence of distinctive features in small
 Fig. 30: Numbers of jack mackerel T.   nooaezelandiae   larvae taken        snapper larvae made initial identification difficult.
   by cruises, 197+-75 and 1975-76.                                          Gradually a series was built up and it showed that the
                                                                             most useful identifying character, before the develop-
                                                                             ment of the fin ray pattern, was the Presence of two
Family Sparidae                                                              pigment spots on the ventral su¡face of the gut (Fig.
Snapper Chrysoþhrys       auratus (Forster,        l80l)                     33 top). These larvae '*'ere confirmed to be snapper by
     Eggs. The snapper egg is described and figured in                       electrophoretic analysis of their enzyme patterns and
Cassiè (1956b) and Crossland (1980). The distribu-                           comparison       with those of the adult (Smith and
tion and abundance of snapper eggs in the Hauraki                            Crossland 1977). Lawae large enough to be identified
Gulf have been    described previously (Crossland                            by their fin ray count (that is, Iarvae more                      than
1980). They were the most abundant of all egg tyPes.                         l0 mm long) were rarely taken.

                                                                                                                       ::.:. .:
                                                                                                                       ':,: ':r'''':
                                                                                                                        5   -20            20-50
                                                                                                                       No. below l0             m2

                     Fig.32: Cumulative distribution of jack mackerel T. decliais eggs. Left: 1974-75' fught: 1975-76'

' i.i'l'::;ïi;j;
                                            '- I '.      ',
                                                                           . .'"
                                                                       _      a     :e

                              Fig. 33: Snapper (Chrysoþhrys auratus)               la*ae   (5.6, 9.7, 13.5 mm).

  The distribution of snapper larvae was patchy in                                                it was lower in 1975-76 than in
                                                                             2 years indicated that
197+-75 (Fig. 34), aqd they were not abundant (Fig.                          the year before and that about the same number of
35). In I975-76 they were much more common, and                              eggs survived to hatch in each year.
more evenly distributed, mainly over the central gulf
(Fig. 3a). Consideration of these facts alone would                                How can the five times greater number of larvae in
                                                                               l97l-70 be explainedl The relative scalci           0f

heavier in I975-76 th'an 1974-75, yet the opposite was                         snapper larvae (even in 1975-76) compared with the
true (Crossland 1980) . A study of egg mortality in the                        larvae of other species whose eggs were much less



                                  /\          L

                              //\ -r^\- V
                      18   -22 Nov     1974

17-   20 Nov   ì975   1-4     Dec 1975                                ló - l9 Dec 1975

                                                  20-50 50-200 200-500 >500
                                                             No. below ]O m2

                           Fig. 34: Distribution of snapper laruae by cruises, 197.[-75 and 197Í176.

           11529          1226        l0    247         21       4
          Oct            Nov          Dec         Jon            Feb

    Fig. 35: Numbers of snapper lawae taken by cruises, t974-7   5
         and 1975-76.

abundant (such as jack mackerel) indicates that the
snapper larva has a short pelagic phase. Cassie
(I956b) observed that newly hatched snapper larvae                                    Fig. 36: Yellow-eyed mullet (Aldrichan forsten) egg.
preferred the bottom            of their    container.
                                                    the   If
demersal habit is quickly adopted, the larvae collected
in the plankton may be mainly those displaced by                               small juveniles the pigmentation merges to form               a
currents or tidal movements. Thus the chances of                               uniform, dark grey background.
sampling them will depend not only on their actual
abundance, but also on the effects of the prevailing                             Larvae, and juveniles up to 33 mm iong, were
weather or the state of the tide. One sample in                                recorded throughout the study area, but were taken
November 1975 taken off the south shore of Kawau                               only occasionally. The occurrence of juveniles during
Island, where tidal movements are.rnore pronounced                             the early part of the study period indicated that
than in open water, contained more laryae than the                             spawning also occurred during late winter and that
total for the whole of the previous year. This is also                         the yellow-eyed mullet has an extended breeding
the only locality in which Cassie (1956b) recorded                             season.
snapper larvae in any numbers.
                                                                               Grey  mullet Mugil æphaløs Linnaeus, 1758
                                                                                 A single juvenile I1.5 mm long was recorded in mid
Family Mugilidae                                                               January 1976. It was very similar to juvenile yellow-
Yellow-eyed mullet Aldrichetta forsteri                                        eyed mullet, but could be distinguished by its having
(Valenciennes, 1836)                                                           only 8 anal soft rays (compared with 12 in the yellow-
                                                                               eyed mullet); both species have 3 spinous rays.
         Eggt. The egg of the         yellow-eyed mullet             is
described in Cassie (1956b). Eggs of this species were
taken in the inner gulf throughout the study period,
but never in large numbers. They ranged in size from
0.84 to 0.93 mm diameter. The number of oil droplets                           Family Labridae
varied from 3 to 13. Late stage eggs were never
recorded; most eggs were at the stage shown in Fig.
                                                                               Spotty Pseudolabrus celidotus (Forster, l80l)
36. The cumulative egg distributions for the 2 years                             Eggs of this common littoral fish, which are
(Fig. 37) showed a spawning centre east of Tiritiri                            described in Robertson (1975), were not recorded
Matangi Island. Eggs were more abundant in 1974-                               during this study.
75 than in the following year.
                                                                                 Larvae. Larvae (Fig. 39) were recorded in small
                                                                               numbers between October and the beginning of
         Lônae, Lawae 0i this         sPecies   ate very dark'                 December and were three times as abundant in 1975-

    because of rnany small melanophores over the whole
    of the body and head (Fig. 3B). In older larvae and
5-20       20 -50
                                                                                                                 No. below l0    m2

                        Fig. 37: Cumulative distribution of yellow-eyed mullet eggs. Left: 1974-75. I{ight: 1975-76.

   Fig. 38: Yellow-eyed mullet (Aldrichettø
     forstcn) Iawa (10.5 mm).

   Fig. 39:   Spotty   (Pseudolabrus celídotus)
     larua (13.2 mm).

Family lJranoscopidae                                                     droplets, and       in the late      stages   only a   single,
Spotted stargazer Genyagnus monoþterygius (Bloch and                      posteriorly placed droplet remained (Fig. a0 bottom).
Schneider, l80l)                                                          The late stage embry¡o was spotted with numerous
                                                                          melanophores; there were also some on the surface of
  Eggs. The spotted stargazer egg is described in                         the yolk. The dorsal median fin fold was strongly
Robertson (1975) (diameter 1.800-2.000 mm; non-                           developed and began at the front of the head.
segmented yolk; three to nine oil droplets). Eggs with
a size range of 1.79-1.96 mm and multiple oil droplets                       Spotted stargazer eggs were recorded consistently
were recorded      in both years (Fig. 40 top). During                    during Octobe¡ and lrTovember of each year, but in
sorting a developmental series of these eggs was built                    only small numbers; from December onwards they
up and it showed that as the egg matured the oil                          were rare. Their distribution (Fig. 4l ) was patchy and
droplets coalesced, so that by the middle stages (Fig.                    widespread, consistent with the occurrence of this
40 centre) there were only two or three larger                            species.

Larvae. These were identified by building up a
developmental series (Fig. a2). The smallest larva
(top) was consistent with the most advanced embryo
(Fig. a0 bottom). The adult fish has a small barbel on
the chin, and this was observed in the largest larva
taken (Fig. 42 bottom), which also showed the
characteristic forward placement of the pelvic fins.
Although no specimen was developed far enough to
allow comparison of fin ray counts, biochemical tests
confirmed the identification. Electrophoretic tissue
analysis by*y colleague P. J. Smith on one of these
Iarvae and on adult spotted stargazer detected a
glucosephosphate isomerase (GPI) Iocus of similar
mobility in both. These loci are good species markers
because of electrophoretic variability of phenotypes
(Avise and Kitto 1973, Dando 1974).

  The cumulative distribution of larvae is shown in
Fig. 43. They were less scattered than the eggs,
commonest in the central gulf during both years, and
taken at all times during the study period.

Families Blenniidae, Clinidae, and Triptery-
   Larvae of these ubiquitous families of fishes (the
adults of which lay demersal eggs) were a common
component of the ichthyoplankton. Most were small
(less than 8 mm), and no attempt was made to
identify them to species level.
                                                                         Fig. 40: Spotted sta¡gazer (Genyagnus monoþtcrygius) eggs.

                                                                                                                 iiii:       t :::::   äi!ii::::t!tl

                                                                                                                         r   -5
                                                                                                                 No. below l0 m2

                    Fig. 4l: Cumulative distribution of spotted stargazer eggs' Left: 1974-75. Right: 1975-76.

Fig.42: Spotted stargazer (Gnlagnus monoþterygius) larvae (5.6, 7.2, 13.8,20.0 mm).

1-2        2- 5
                                                                                                                   No. below l0         m2

                   Fig. 43: Cumulative distribution of sported stargazer larvae. Left: 197+-75. Right: 1975-76.

Family Eleotridae                                                    Family Scombridae
Graham's gudgeon      Grahamichthys radiatus (Quoy and               Blue mackerel Scomber australasicus Cuvier and
Gaimard, IB37)                                                       Valenciennes, 1831
  Larvae. Larvae of this species (another which lays                    The eggs and larvae of this species were identified
demersal eggs) are shown in Fig. 44.Tlne young larva                 from their close similarity to those of the Pacific
(top) is transparent and has a conspicuous swim                      (Japanese) mackerel Scomber japonicus (:
bladder which becomes less prominent as the larva                    Pneumatoþhorus diego)     (Kramer 1960).
matures (bottom). These larvae-were common and
were taken throughout the sampling period, being                       Eggs. These eggs (Fig. 46) had a diameter of I.05-
most abundant from late November onwards in 1974                     1.20   mm; a narrow perivitelline space; a non-
and from early December in 1975. Their distribution                  segmented yolk; anda single oil droplet of 0.26-
was similar in both years (Fig. 45) and extended in a                0.33 mm diameter, situated posteriorly in late stage
broad band across the northern half of the studv area.               eggs. The advanced embryo is moderately pigmented
                                                                     dorsally and laterally, from the head almost to the tip
Family Gempylidae                                                    of the tail. A few melanophores also occur on the
Barracouta Thyrsites atun Euphrasen, l79l                            surface of the yolk near the embryo.
  Ten specimens of larvae and pre-juveniles were
taken in the outer stations on the first cruise in 1974.               BIue mackerel eggs were taken throughout the
They ranged in length from 7.5 to 25 mm.                             study period in 1974-75. Their abundance varied

                                                                                            Fig.   .14:   Graham's gudgeon (Gralary-
                                                                                              lchtþs radiatu) larvae            (4.9,
                                                                                               12.2   mm),

r-.5 5-t0             10-20
                                                                                                                        No. below l0       m'?

                     Fig. 45: cumulative dis¡¡ibution of G¡aham's gudgeon larvae.         Lelt: lg74-75. -Right:   1975-76.

greatly from cruise to cruise (Fig. 47), which is to be                top of the head and           derLse   pigmentation on rhe sides of
expected with this highly mobile schooling {ish. The                   the visceral cavity. These leatures distinguish them
spatial distribution (FiS. 48) showed the main                         from snapper larva€:, which they s.uperficially
spawning area to be outside the study a¡ea or on irs                   resemble in the early stages. Details of pigmentation
northern periphery. In 1975-76 this part of the gulf                   are remarkably similar ro rhose of the Pacific mackerel
was not sampled and blue mackerel eggs were less                       described by Kramer (1960). However, larvae of S.
common, being taken in large numbers only during                       australasicus are more slender and have less developed
one cruise.                                                            fin rays than S. jaþonints larvae of comparable length.
                                                                       The largest larva recorded was 19 mm long.
  Larvae. Blue mackerel larvae (FiS. 49)                    are
characterised by a patch of round meianophores on                             Blue mackerel were among the most abuñdant
                                                                       Iarvae in plankton from the outer stations; on several
                                                                       occasions over 1000 were taken in one sample, and a
                                                                       maximum of 2704 tvas recorded. The seasonal
                                                                       variation in larval numbers (Fig. 50) showed two
                                                                       marked peaks in both seasons. I was not able to
                                                                       determine whether these were caused by chance
                                                                       during sampling or were a significant feature of the
                                                                       spawning of this species. The distribution of larvae
                                                                       (Fig. 5l) was similar in both years and was centred
                                                                       close to the observed spawning areas, but dispersed
                                                                       further south into the central gulf.


                                                                        l l'r529
                                                                       z Oct                        1226 1024721                                 4
                                                                                                    Nov  Dec   Jon                            Feb

       Fig. 46: Blue macke¡el (Scomber australasims) egg.
                                                                        Fig.47: N_umbers         of blue mackerel     eggs taken   by   cruises,
                                                                              r974-7 5.

                                             l8 - 22 Nov   1974

                                                                                                             ::r   ¡::!:i*i:i::.¡i:i:i

                                                                                           50-200 200-500                                500-     >1000
                                                                                                                   No. below l0 m'

  16 -   20 Dec 1974                         20-23   Jon1975

   lZ-21 Nov     197                             Fig. 48: Distribution of blue mackerel eggs by cruises, 1974-75 and 1975-76

Family Bothidae                                                        (Arnoglossus scapha (BIoch and Schneider,                                1B0l))   (see

Crested flounder Loþhonectes gallus Gunther, 1880                      Robertson 1975    for          eggs and Robertson 1973 for
  The eggs of this species have not previously been
described from New Zealand, and the larvae have
been described only in an unpublished account                            Eggs. These eggs (Fig. 52) had a diameter of 0.81-
(Robertson 1973). Eggs and larvae were identilied by                   0.88mm; a non-segmented yolk; and a single oil
                                    and raryar series'   rh1           droolet of 0.I2-0.16 mm diameter. Crested flounder
fllllülllf   l¡ ft[ IlllfIÎt'¡nut                                          lll
closely resemble those of the related species witch                    eggs were taken at the outer stations on every crulse In

Fig.   49:   Blue mackerel        (Seomber
         australasicus)   larvae (9 4, I4.4 mm).

       or                                           1974-75                bothid larvae taken in this study were positively
                                                                           identified as those oÍ L. gallus by their fin ray counts.
                                                                           Loþhonectes   gallushas 87 to 93 dorsal rays and   7l to 77
                                                                           anal rays; A. scaþha has ltl to 126 and 87 to 99
                                                                           respectively (Norman 1934). The largest
'o                                                                         recorded was 14 mm long, at which size metamor-
 )(                                                                        phosis had not begun.
                                                                              IJnlike the eggs, Iarvae of crested flounder were at
                                                                           times abundant, particularly in 1975-76, when as
                                                                           many as 152 were recorded in a sample. The larval

-o                                                                         distribution (Fig. 55) shows dispersion south into the
                                                                           central gulf from the northern spawning centre. This
                                                                           was more marked in 1975-76, when larvae were
                                                                           common as far south as Tiritiri Matangi Island.
                                                                           Although larvae were taken on all cruises in both
                                                                           years, their numbers varied greatly, and periods of
                                                                           abundance did not correspond in the 2 years. In
                                                                           1974-75larvae were common on the first three cruises
        11529                 1226r0    24721                    4
                                                                           (October and November);       in   1975-76 they were rare
       Oct                    Nov   Dec    Jon                  Feb
                                                                           on the first three cruises, suddenly became abundant
   Fig. 50: Numbers of blue mackerel larvae taken     by   cruises,        on the fourth cruise (mid November), and continued
      1974-75 and 1975-76.                                                 to be so until the end of December.
                                                                             The thin, Ieaf-life form of the crested flounder larva
1974-75,  but were never common excePt at one                              indicates that it is a weak swimmer and is probably
station off the south-west shore of Great Barrier                          more truly planktonic than many other fish larvae and
Island (Fig. 53). The spawning area aPPears to be                          thus more affected by water movements. This, with its
north of the study area.                                                   Iong larval period, means that it can occur in samples
                                                                           taken a considerable distance from the spawning site.
  Larvae. The ybung larva (Fig. 54 top) is quickly
recognisable by a prominent band of black pigment
near the tail and by the bifid whisker on top of the
head. (Sometimes only a single ray was present,                            Family Pleuronectidae
possibly as a result of damage.) Larger larvae are                           Three members of this family are commonly found
transparent and every detail of the viscera and                            in the Hauraki Gulf: the sand flounder       (Rhombosolea
structure of the gills is visible. They also have the bifid                þlebeia Richardson, 1843), the yellow-belly flounder
whisker. These features also apply to the larvae of the                    (R.   leporina   Günther, lB73), and the speckled sole
more southerly distributed A. scaþha. ÉIowever, the                        (Peltorhamþhus latus James, 1972). The development of

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