When and why do smallmouth bass abandon their broods? The effects of brood and parental characteristics
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Fisheries Management
and Ecology
Fisheries Management and Ecology, 2011, 18, 1–11
When and why do smallmouth bass abandon their
broods? The effects of brood and parental
characteristics
G. B. STEINHART & B. D. LUNN*
School of Biological Sciences, Lake Superior State University, Sault Sainte Marie, MI, USA
Abstract Variation in brood abandonment was explored by conducting partial brood removals from small-
mouth bass, Micropterus dolomieu Lacepède, nests in two north temperate lakes. In both lakes, percent of the
brood removed had no effect on nest failure rates. Nest failure prior to offspring swim-up was more common,
but unrelated to brood size after removal, in the lake with higher post-spawning mortality and lower growth and
fecundity. Brood size after removal was negatively related to nest failure in the lake with high survival, growth
and fecundity. Nests guarded by young males failed more frequently than those of old males, and young broods
failed more frequently than old broods. Dynamic programming and logistic regression models developed to
predict nest fate worked better for the lake with selective pressures that theoretically favoured abandonment (e.g.
high post-spawning mortality). Both models identified male age and brood age as important factors in predicting
nest fates. Because nest success is related to the age of the parent, this could have consequences for overall nest
success for populations with different demographics.
KEYWORDS: brood abandonment, brood predation, Micropterus dolomieu, nest success, parental care.
dity, as well as juvenile survival and growth (Clutton-
Introduction
Brock 1991; Stearns 1992; Hutchings 1993). For
Parental care can be energetically costly for a parent species that care for their offspring, current brood size
but is required for many species or the offspring will is an important factor determining the amount of care
perish. Providing care can reduce parental survival, provided (Armstrong & Robertson 1988).
growth and breeding interval, thus reducing future There is considerable variation in the amount of
breeding attempts and their expected future fitness parental care provided among different species. Brood
(Sabat 1994; Balshine-Earn 1995; Székely & Cuthill abandonment following changes to the current brood
2000). Therefore, species that provide parental care varies. The most common pattern in birds has been an
face a trade-off between current and future fitness increase in brood abandonment with a reduction in
(Williams 1966; Trivers 1972). If the benefits to future clutch size (Armstrong & Robertson 1988; Székely &
fitness by abandoning the current brood exceed the Cuthill 2000), but there are exceptions. Nests para-
expected return of continuing to provide care, aban- sitised (i.e. loss of at least some of the original brood)
donment would be the optimal behaviour. Although by brown-headed cowbirds, Molothrus ater Boddaert,
individuals might not be continuously assessing the have been reported to have both higher abandonment
costs and benefits of guarding or abandoning their rates (Clotfelter & Yasukawa 1999) and little change in
brood, natural selection should favour those that abandonment (Whitehead et al. 2000). Eurasian kes-
choose the behaviour that increases lifetime fitness. trel, Falco tinnunculus L., parental effort has been
In this theoretical context, reproductive effort, includ- reported to remain relatively constant across manipu-
ing providing care, should be predictable and probably lated brood sizes (Tolonen & Korpimäki 1996) and to
depends on factors such as adult survival and fecun- be positively related to brood size (Dijkstra et al.
Correspondence: Geoffrey B. Steinhart, School of Biological Sciences, Lake Superior State University, 650 W. Easterday Avenue, Sault Sainte
Marie, MI 49783, USA (e-mail: gsteinhart@lssu.edu)
*Present address: Department of Biological Sciences, University of Alberta, Edmonton, AB, Canada T6G 2E9.
2010 Blackwell Publishing Ltd. doi: 10.1111/j.1365-2400.2010.00758.x 12 G. B. STEINHART & B. D. LUNN
1990). In addition, red-backed salamanders, Plethodon Canada. Lake Opeongo (58.6 km2) contains various
cinereus Green, also tend to abandon small broods fishes, including yellow perch, Perca flavescens
more than large broods (Yurewicz & Wilbur 2004). (Mitchill), pumpkinseed, Lepomis gibbosus (L.), lake
Fishes also demonstrate increased abandonment or trout, Salvelinus namayacush (Walbaum), several cor-
filial cannibalism of small broods (Petersen 1990; Suski egonids and many cyprinids (Martin & Fry 1973).
et al. 2003; Hanson et al. 2007). Finally, cuckoldry Provoking Lake is only 11 km2 and supports only
(extra-pair fertilisations) often result in cannibalism or smallmouth bass, splake, S. namaycush · Salvelinus
abandonment in fishes and birds (Mauck et al. 1999; fontinalis (Mitchill), and yellow perch. Both lakes have
Neff 2003). populations of smallmouth bass that were introduced
Although one might think parental care is predict- in the early 1900s. The smallmouth bass populations
able, it is apparent that there is considerable vari- are quite different, however, with the Provoking Lake
ability that may be caused by environmental or population characterised by higher densities, slower
demographic differences among populations. The growth rates, earlier maturation and higher post-
goal of this research was to assess variability in spawning mortality than smallmouth bass in Lake
parental care in a nest-guarding fish, the smallmouth Opeongo (Dunlop et al. 2005).
bass, Micropterus dolomieu Lacepède, in lakes with Snorkel surveys were conducted during 31 May to
different selective pressures. Male smallmouth bass 12 June 2007 in Opeongo and 3 June to 29 June 2008 in
provide sole parental care for their offspring, some- Opeongo and Provoking to locate smallmouth bass
times for more than 1 month (Ridgway 1988). As nests and monitor their success following experimental
with other organisms, this care is costly, resulting in brood removals. Different stretches of shoreline were
increased mortality (Ridgway 1986; Dunlop et al. sampled each year in Lake Opeongo to avoid any
2005) and a loss of energetic content (Gillooly & resampling or cumulative effects of the brood remo-
Baylis 1999; Mackereth et al. 1999; Steinhart et al. vals. Nests were marked with numbered rocks to
2005b), the latter of which may reduce the number of ensure proper identification on subsequent visits that
eggs a male receives in the future (Wiegmann et al. occurred typically every 2 days (range 1–4 days). Male
1992; Mackereth et al. 1999). Angling of nest-guard- presence or absence and offspring developmental stage
ing males can substantially increase brood abandon- were recorded on each visit. Developmental stages
ment in some systems (Suski et al. 2003; Hanson were defined as unhatched embryos (eggs), hatched
et al. 2007), but in other lakes the effects are minor embryos (clear fry or pigmented fry), larvae (swim-up
(Steinhart et al. 2005a). fry) or juveniles (green fry still associated with a nest
The specific objectives of this study were to: (1) and guarding male). Nests containing free-swimming
assess if experimentally reduced broods were more larvae were deemed successful while nests that did not
likely to fail than unmanipulated broods; (2) explore reach the larval stage were considered failures. Because
how male age, and brood age and size affected nest angling for smallmouth bass was not allowed during
failures; and (3) evaluate two modelling techniques for the survey period and there are few predators of adult
predicting nest abandonment. From parental care smallmouth bass in the lakes, nest failures were
theory, it was hypothesised that nest failure (i.e. considered abandoned nests, although unobserved
abandonment) would increase as the percent brood sources of adult or offspring mortality could have led
removed increased and as male age, brood size and to some nest failures.
brood age decreased. If brood abandonment is pre- Brood-removal treatments were systematically as-
dictable, then it may be possible to forecast the signed to nests starting with 0% brood removal and
potential effects of perturbations, such as angling, that continuing to 25%, 50%, or 75% brood removal.
affect parental behaviour and even predict resulting However, because treatment assignments varied in
impacts on offspring production or recruitment suc- space (i.e. where nests were found or treated on a
cess. given day) and time (i.e. the day nests were found or
treated), the treatment assignments were essentially
random. Some newly discovered nests had treatment
Methods
assignments reserved for a later date to allow for
manipulation of older broods. For all treatments,
Field surveys
nest-guarding smallmouth bass were removed from
Smallmouth bass nests were located via snorkelling their nests via angling with a single-hook jig. Total
surveys in known spawning areas in Lakes Opeongo length (TL, mm) and wet weight (nearest 5 g) were
and Provoking, Algonquin Provincial Park, Ontario, measured, scale samples were collected to estimate
2010 Blackwell Publishing Ltd.VARIABILITY IN SMALLMOUTH BASS PARENTAL CARE 3
age and then the fish was released. This procedure
Predictive modelling
was performed as quickly as possible (typically4 G. B. STEINHART & B. D. LUNN
Table 1. Age-dependent parameter values for male smallmouth bass most parsimonious model(s), those with the best
included in the stochastic dynamic programming model. Smallmouth combination of the best fit and the fewest parameters.
bass in Lakes Opeongo and Provoking had different total length at
Models were ranked based on the model likelihoods.
age (TL, in mm), initial brood size (B), adult annual survival rate
(ASR) and cost of parental care (DASR; daily reduction in ASR
The ratio of likelihoods, or evidence ratio, shows how
when guarding). See the Methods for explanations of parameters much more likely one model is compared with another.
values Normalised Akaike model weights, often treated as the
probability of a model being the best-supported model
Lake Opeongo Provoking Lake
among all candidates, were calculated. Individual
Age TL B ASR DASR TL B ASR DASR variables were ranked by summing all Akaike weights
for models containing that particular variable
4 259 940 0.7 0.025 255 927 0.7 0.038
(Burnham & Anderson 2002).
5 285 1474 0.6 0.015 284 1175 0.6 0.028
6 323 2256 0.5 0.008 306 1360 0.5 0.021
7 355 2914 0.45 0.0015 322 1498 0.45 0.015 Results
8 382 3469 0.4 0.001 334 1602 0.4 0.014
9 406 3963 0.4 0.001 343 1679 0.4 0.014
10 428 4415 0.4 0.001 350 1736 0.4 0.014 Field surveys
11 448 4827 0.3 0.001 355 1779 0.3 0.014 A total of 138 nests, 105 in Lake Opeongo and 33 in
12 466 5197 0.2 0.001 359 1812 0.2 0.014
Provoking Lake, were monitored until they were
13 482 5526 0.1 0.001 362 1836 0.1 0.014
14 497 5835 0.05 0.001 365 1863 0.05 0.014 deemed successful or failures (Table 2). In general,
15 512 6143 0.01 0.001 368 1888 0.01 0.014 guarding male smallmouth bass were older, larger and
16+ 512 6410 0.01 0.001 370 1905 0.01 0.014 had larger broods in Lake Opeongo than in Provoking
Lake. However, within each lake male age, brood age
at treatment or estimated brood size before treatment
same as Lake Opeongo. Because providing care is did not differ among brood-removal treatments
energetically costly, annual survival rates and lost (Table 2).
growth potential were modified based on the duration Nest failure rates generally were lower in Lake
of parental care. Annual survival for nesting vs non- Opeongo (22 of 105 nests, 21% failed; Fig. 1) than in
nesting males is known to decline at different rates in Provoking Lake (13 of 33 nests, 39% failed). Neither
each lake, so daily declines in annual survival for nest- year (WaldÕs statistic = 2.68, P = 0.10), treatment
guarding males were higher in Provoking Lake than level (WaldÕs statistic = 0.86, P = 0.35) nor the
Lake Opeongo and were based on observed post- model with treatment and year (Likelihood ratio
nesting mortality rates (Table 1; Dunlop et al. 2005). v2 = 3.63, P = 0.16) affected nest failure rate in Lake
Change in length was estimated in Lake Opeongo Opeongo. In Provoking Lake, nest failure rate was not
()0.5 mm day)1 of care; Steinhart et al. 2008) and affected by treatment (Likelihood ratio v2 = 0.08,
assumed similar for Provoking because similar preda- P = 0.77). Although the brood-removal treatment
tor burdens are likely to lead to similar energetic costs had no effect on nest fate, brood size after treatment
of care (Steinhart et al. 2005b). In summary, model was significantly lower for failed nests (1554 ± 262
parameters were assumed similar in the two lakes offspring; mean ± SE) than successful nests
except for change in annual survival from providing (2150 ± 229) in Opeongo (t = 1.71, d.f. = 57,
care, length at age and initial brood size. Full details P = 0.046; Fig. 2a). In Provoking, however, there
on construction and exploration of the DP model are was no difference in brood size after treatment between
available in Steinhart et al. (2008). successful (837 ± 118 offspring) and failed
For the logistic regression analysis, the a priori set of (663 ± 141) nests (t = 0.94, d.f. = 31, P = 0.18).
candidate models included all possible models using Nest fate was related to male length, age and brood
one or more of the following variables: male age, age in both lakes. In Lake Opeongo, failed nests were
brood age, brood-removal treatment and brood size guarded by males that were on average 34-mm shorter
after treatment to predict nest fate as a binary variable (t = 2.76, d.f. = 48, P = 0.004; Fig. 2b) and 1.3-year
(i.e. success = 0 or failure = 1). Year was not younger (t = 3.66, d.f. = 66, P < 0.001; Fig. 2c)
included as a variable in any model as year affects than males with successful broods. Failed nests were
are likely driven by unpredictable weather. AkaikeÕs 1.9-day younger on the day of brood removal than age
Information Criterion adjusted for small sample size of successful nests in Lake Opeongo (t = 4.37,
(AICc; Burnham & Anderson 2002) was used to d.f. = 73, P < 0.001; Fig. 2d). Nests that failed in
evaluate competing models. AICc scores identified the Provoking Lake also were guarded by smaller (274 vs
2010 Blackwell Publishing Ltd.VARIABILITY IN SMALLMOUTH BASS PARENTAL CARE 5
Table 2. Mean (±standard error) age, total length, brood size and nest age at treatment of nests treated in Lake Opeongo (2007 and 2008) and
Provoking Lake (2008)
Brood-removal treatment
Lake Variable 0% 25% 50% 75% All ANOVA
Opeongo Sample size 25 27 26 27 105
Male age (years) 7.6 ± 0.4 7.6 ± 0.4 8.2 ± 0.5 7.7 ± 0.4 7.8 ± 0.2 F3,101 = 0.42
P = 0.74
Total length (mm) 362 ± 12 363 ± 13 375 ± 13 368 ± 13 367 ± 6 F3,101 = 0.22
P = 0.89
Brood size 3229 ± 218 3554 ± 693 3379 ± 650 2579 ± 443 3182 ± 269 F3,101 = 1.03
P = 0.38
Brood age (days) 3.7 ± 0.4 4.1 ± 0.6 4.3 ± 0.6 4.4 ± 0.6 4.1 ± 0.3 F3,101 = 0.31
P = 0.82
Provoking Sample size 8 8 8 9 33
Male age (years) 6.6 ± 0.4 6.8 ± 0.7 7.3 ± 0.8 7.0 ± 0.4 6.9 ± 0.3 F3,29 = 0.22
P = 0.88
Total length (mm) 282 ± 12 303 ± 20 299 ± 13 290 ± 8 294 ± 7 F3,29 = 0.45
P = 0.72
Brood size 1143 ± 101 1524 ± 272 1082 ± 246 1217 ± 243 1241 ± 112 F3,29 = 0.72
P = 0.55
Brood age (days) 4.1 ± 0.7 4.4 ± 0.7 4.1 ± 0.5 4.6 ± 0.7 4.3 ± 0.3 F3,29 < 0.001
P = 0.99
Predictive modelling
The most parsimonious logistic regression model in
both lakes included only male age and brood age at
treatment (Table 3). In both lakes, the best-supported
models were more than twice as likely to be the best
models as the second-most parsimonious models. For
Lake Opeongo, the model containing male age and
brood age at treatment was a significant predictor of
nest failure (Likelihood ratio v2 = 16.42, P < 0.001).
The second-best model in Lake Opeongo contained
both brood age and brood remaining after treatment,
and the third-best model contained only brood age. In
Provoking Lake, the model containing brood age and
male age was also the best model and a significant
predictor of nest fate (Likelihood ratio v2 = 12.22,
P = 0.002); the second-best model contained only
Figure 1. Percent nest failure for smallmouth bass nests after catch- brood age, and the third-best-supported model con-
and-release angling and partial brood removal in Lake Opeongo in 2007 tained only male age.
(black circles) and 2008 (white circles) and in Provoking Lake (grey
Additional support for the importance of male age
squares). See Table 2 for sample sizes.
and brood age at treatment was seen after summing
Akaike weights for each model containing a particular
variable. Models containing brood age at treatment
306 mm; t = 2.48, d.f. = 31, P = 0.009; Fig. 2b) and had the greatest sum (0.96 for Opeongo and 0.79 for
younger (6.1 vs 7.4 years; t = 2.32, d.f. = 31, Provoking), and models with male age had the second
P = 0.01; Fig. 2c) males than successful nests. Failed highest (Opeongo = 0.65, Provoking 0.72). Models
nests in Provoking Lake also contained younger containing brood remaining (Opeongo = 0.32, Pro-
offspring when brood removal occurred than success- voking 0.18) or percent of brood removed
ful nests (3.5 vs 4.9 days; t = 2.46, d.f. = 31, (Opeongo = 0.20, Provoking 0.12) had much lower
P = 0.01; Fig. 2d). summed Akaike weights. Male age and brood age had
2010 Blackwell Publishing Ltd.6 G. B. STEINHART & B. D. LUNN
(a) (b)
(c) (d)
Figure 2. Nest-guarding male and brood characteristics for successful (grey bars) and failed (white bars) nests in Lakes Opeongo and Provoking. All
characteristics were different (P < 0.05) between successful and failed nests except for brood size in Provoking Lake.
Table 3. Logistic regression models for predicting smallmouth bass nest failure and their associated values for AkaikeÕs Information Criteria
(corrected for small sample sizes, AICc), model likelihoods and normalised Akaike model weights. Models are shown in order of decreasing
likelihood for Lake Opeongo
Lake Opeongo Provoking Lake
Model AICc Model likelihood Model weight AICc Model likelihood Model weight
Brood age, male age 103.4 1.00 0.37 44.9 1.00 0.40
Brood age, brood remaining 105.0 0.45 0.17 48.7 0.15 0.06
Brood age 105.6 0.32 0.12 46.5 0.43 0.17
Brood age, male age, treatment 105.6 0.32 0.12 48.8 0.14 0.06
Brood age, brood remaining, male age 105.9 0.28 0.10 48.2 0.18 0.07
Brood age, treatment 108.4 0.08 0.03 50.7 0.05 0.02
Male age 108.6 0.07 0.03 46.9 0.37 0.15
Brood age, brood remaining, treatment 109.1 0.06 0.02 52.8 0.02 0.01
Brood age, brood remaining, male age, treatment 109.5 0.05 0.02 53.0 0.02 0.01
Male age, treatment 111.5 0.02 0.01 50.9 0.05 0.02
Brood remaining, male age 112.6 0.01 0.00 51.1 0.05 0.02
Brood remaining 114.0 0.00 0.00 51.7 0.03 0.01
Treatment 115.0 0.00 0.00 52.6 0.02 0.01
Brood remaining, male age, treatment 115.5 0.00 0.00 55.5 0.00 0.00
Brood remaining, treatment 118.0 0.00 0.00 55.9 0.00 0.00
negative coefficients indicating that older males and broods and nests with a lower percent of offspring
older broods were more likely to be successful than removed to be more successful.
young males or young broods. Although the results Despite the relative statistical superiority of the best-
suggest that the brood remaining after treatment and fitting logistic models, the models had mixed results for
percent of brood removed were not strong predictors predicting brood failure (Table 4). The most parsimo-
of nest fate, the coefficients suggested a trend for larger nious logistic model correctly predicted 75% of nest
2010 Blackwell Publishing Ltd.VARIABILITY IN SMALLMOUTH BASS PARENTAL CARE 7
Table 4. Classification matrix for the logistic regression models and logistic models. This supports the idea that parental
dynamic programming (DP) models for actual smallmouth bass nest investment is tied to factors other than number of
fates (failed or successful) and model predicted fates. Bold numbers
offspring (Tolonen & Korpimäki 1996). Indeed, an
indicate correct classifications
analysis of 20 years of nesting data from Lake Ope-
Opeongo Provoking ongo revealed that male body size, which was strongly
related to male age, was an important predictor of nest
Failed Successful Failed Successful
success, especially later in the parental care period
Logistic model when the energetic costs of care may lead small males
Predicted failure 0 4 10 4 to abandon (Suski & Ridgway 2007). In addition,
Predicted success 22 79 3 16 Steinhart et al. (2008) provided evidence from simula-
DP model
tion models that annual adult survival was the most
Predicted failure 3 8 5 5
Predicted success 19 75 8 15 important factor affecting brood abandonment of
nesting smallmouth bass. Functionally, adult survival
and male age may have a similar effect on parental
behaviour because they both relate to the expected
fates in Lake Opeongo and 79% of fates in Provoking. number of future breeding attempts: old males or
Predicting nest failures was problematic in Lake males with low annual survival have fewer expected
Opeongo: no failed nests were classified as such. The future breeding attempts and, therefore, should be
best-supported logistic model performed better in more likely to guard their current brood. A growing
Provoking Lake, correctly predicting 71% of nest body of literature suggests that size-selective fishing
failures. The DP model correctly classified 74% of all mortality affects many life-history and behavioural
nest fates in Lake Opeongo, but only 14% of failed traits, sometimes in only a few generations (e.g. Olsen
nests were predicted to be abandoned. For Provoking et al. 2004; Walsh et al. 2006). For fish that provide
Lake, the DP model correctly classified 61% of the care when faced with high adult mortality (i.e. few
nest fates and 38% of the nests that failed. breeding attempts), the most successful fish would
likely be those that guard their broods even when the
fitness value of the offspring is relatively low. Con-
Discussion
versely, fish that were prone to abandoning would be
Brood size and percent brood reduction had little effect less likely to produce a successful brood during their
on nest failure in this study. Specifically, percent of few reproductive attempts and their genotype would be
brood removed did not significantly affect nest failure less likely to persist. Alternatively, if high annual
in either study lake, and brood size affected nest failure mortality reduces smallmouth bass density and in-
only in Lake Opeongo but was not an important creases their growth rates, individuals may be able to
variable in the logistic regressions for either lake. These allocate more time and energy to parental care, again
results may have been influenced by the great variabil- resulting in an increased willingness to guard small
ity in the number of eggs received by male smallmouth broods.
bass. Multiple linear regressions using male length and Because annual survival, growth and cost of care
spawning date to predict brood size had low coeffi- vary among systems (Dunlop et al. 2005; Steinhart
cients of determination (8 G. B. STEINHART & B. D. LUNN
of brood size not being important in determining nest
failure in Provoking, while brood age and male age
were, supports that notion that population demo-
graphics may be important to parental care behaviour.
In systems where brood size is not an important factor
in nest failure, brood predation should not lead to
increased nest failures, as was demonstrated in Lake
Erie (Steinhart et al. 2005a).
It is unclear why both modelling techniques were
better at predicting abandonment in Provoking Lake
than in Lake Opeongo. One possibility is that the
demographics in Provoking, which were characterised
by slow growth, high post-spawning mortality and low
fecundity, select for fish that have a better-defined and
higher brood-size abandonment threshold because
providing care more strongly affects future fitness via
poor growth and survival in Provoking Lake. In the Figure 3. Change in nest failure rate following brood reduction,
more benign Lake Opeongo, higher expected fitness compared to control treatments, in four different studies. All nest-
guarding males were angled for both control and removal treatments.
and lower consequences for providing care (i.e. costs
Data from Opeongo (white bars) and Provoking (black bars) are from
are ameliorated by better growth during the non- this study. Steinhart et al. (2005a) estimated brood reduction from
nesting season) may allow males to be more flexible in natural predation to be 25–50% of the brood size in Lake Erie, Ohio
providing care. An alternative hypothesis is that some (grey bars; n = 131 controls and 65 removals). Suski et al. (2003)
males may have abandoned in Lake Opeongo because manipulated broods in Charleston Lake, Ontario (stippled bars; n = 11
of storms that created waves and may have cause rapid controls and 10 removals). Hanson et al. (2007) studied Devil and
temperature changes as a result of seiches (MacLean Wolfe Lakes, Ontario (cross-hatched bars; n = 12 controls and 12
removals).
et al. 1981). Such storm events would likely be more
common in larger Lake Opeongo than in Provoking
and would not be predicted in the models. Finally, Other studies have examined the effect of brood
several DP model parameter values were assumed, removals on smallmouth bass nest success with vari-
especially for Provoking Lake fish, which may have led able conclusions (Fig. 3). In Lake Erie, Ohio, where
to poor prediction of nest abandonment. The variables nest predators [i.e. round gobies, Neogobius melano-
deemed most important to the DP model by Steinhart stomus (Pallas)] are extremely abundant, brood preda-
et al. (2008) were adult annual survival and cost of tion during catch-and-release angling typically resulted
providing care. For this study, it was assumed that the in a loss of 25–50% of the offspring in a nest (Steinhart
base annual survival rates were identical in both lakes. et al. 2004a), but this predation resulted in no differ-
If poor growth rates, or some other factor, in Provok- ence in nest success from control nests (Steinhart et al.
ing Lake led to lower annual survival than what was 2005a). Smallmouth bass in Lake Erie have high
used in the DP simulation, it would lead to an growth rates compared with many other populations
underestimation of brood abandonment (i.e. high (Doan 1940; Steinhart et al. 2004b), likely ameliorating
adult survival in the model would favour nest aban- the cost of providing care (Steinhart et al. 2005b).
donment). Despite this shortcoming, the results sug- Relatively high angling pressure should increase mor-
gest that the model worked better in Provoking Lake tality and lead to a shorter expected life span in Lake
than in Lake Opeongo, so the assumed base survival Erie than in lakes in this study and, possibly, a Ôgrow
rates might not have been as important as the and reproduce quicklyÕ life history (Shuter et al. 2005).
adjustments to annual survival based on duration of These factors should favour a guard strategy even at
parental care which were based on known values small brood sizes. In limited experimental brood
(Dunlop et al. 2005). Therefore, although not all manipulations (25%–75% of offspring removed) in
model parameters were explicitly measured in the field, Lake Erie, 10 of 11 males continued to guard their
the results still point towards a stronger effect of brood broods after brood reduction, at least until a storm
age, male age and adult annual survival (including the occurred (mean 6 days, range 0–19 days; Steinhart
effects of parental care on adult survival) on nest et al. 2005a).
success than the effects of brood size and brood By contrast, removing 50% of broods in Charleston
reduction. Lake, Ontario, led to a 61% increase in abandonment
2010 Blackwell Publishing Ltd.VARIABILITY IN SMALLMOUTH BASS PARENTAL CARE 9 compared with an angled control (Suski et al. 2003). In prone to abandonment and, therefore, might benefit the Suski et al. (2003) study, manipulated nests were from more protective regulations. For example, estab- limited to average-sized broods guarded by average- lishing no-take zones or minimising disturbances may sized males (presumably these were not the youngest produce a greater increase in offspring production in individuals to spawn). Because the current study systems where males are more likely to abandon (e.g. suggests that young males are more prone to aban- lakes with high mortality, low growth or fecundity, or donment, the brood removals in Charleston Lake may high parental care cost) than in systems where males have been biased towards males that were less likely to tend to guard. Therefore, fisheries managers may be abandon, which means that across the whole popula- able to improve their ability to manage populations tion the increase in nest abandonment could have been when they can predict the effects of angling on the nest higher. Furthermore, only nests older than 4 days were success based on relatively simple-to-collect demo- manipulated by Suski et al. (2003), again biasing the graphic parameters (e.g. annual survival, age struc- sample towards broods that, based on the results of the ture). While the model simulations did not do a good current study, may have been less likely to be aban- job in predicting abandonment, characteristics of the doned. Another manipulation study removed 90% of nest and the guarding male did vary among successful the brood from smallmouth bass nests in Devil and and failed nests. Future efforts can refine these models Wolfe Lakes, Ontario (Hanson et al. 2007). For the and consider other variables to improve the ability to Hanson et al. (2007) study, there was no male size- predict brood abandonment for smallmouth bass and selection and only young nests (
10 G. B. STEINHART & B. D. LUNN
Cooke S.J., Weatherhead P.J., Wahl D.H. & Philipp D.P. Ridgway M.S. (1986) Factors Governing Patterns of Brood
(2008) Parental care in response to natural variation in nest Defense in Male Smallmouth Bass (Micropterus dolo-
predation pressure in six sunfish (Centrarchidae: Teleostei) mieui). PhD Dissertation, London, ON: University of
species. Ecology of Freshwater Fish 17, 628–638. Western Ontario, 188 pp.
Dijkstra C., Bult A., Biljsma S., Dann S., Meijer T. & Zijlstra Ridgway M.S. (1988) Developmental stage of offspring and
M. (1990) Brood size manipulations in the kestrel (Falco brood defense in smallmouth bass (Micropterus dolomieui).
tinnunculus): effects on offspring and parental survival. Canadian Journal of Zoology 66, 1722–1728.
Journal of Animal Ecology 59, 268–285. Ridgway M.S. (1989) The parental response to brood size
Doan K.H. (1940) Studies of smallmouth bass. Journal of manipulation in smallmouth bass (Micropterus dolomieui).
Wildlife Management 4, 241–266. Ethology 80, 47–54.
Dunlop E.S., Orendorff J.A., Shuter B.J., Rodd F.H. & Ridgway M.S. & Philipp D.P. (eds) (2002) Current status and
Ridgway M.S. (2005) Diet and divergence of introduced future directions for research in the ecology, conservation,
smallmouth bass (Micropterus dolomieu) populations. and management of black bass in North America. In:
Canadian Journal of Fisheries and Aquatic Sciences 62, Black Bass: Ecology, Conservation, and Management.
1720–1732. Bethesda, MD: American Fisheries Society, pp. 719–724.
Gillooly J.F. & Baylis J.R. (1999) Reproductive success and Sabat A.N. (1994) Cost and benefits of parental effort in a
the energetic cost of parental care in male smallmouth brood-guarding fish (Ambloplites rupestris, Centrarchidae).
bass. Journal of Fish Biology 54, 573–584. Behavioral Ecology 5, 195–201.
Hanson K.C., Cooke S.J., Suski C.D. & Philipp D.P. Shuter B.J., Lester N.P., LaRose J., Purchase C.F., Vascotto
(2007) Effects of different angling practices on post-re- K., Morgan G.E., Collins N.C. & Abrams P.A. (2005)
lease behaviour of nest-guarding male black bass, Optimal life histories and food web position: linkages
Micropterus spp. Fisheries Management and Ecology 14, among somatic growth, reproductive investment, and
141–148. mortality. Canadian Journal of Fisheries and Aquatic Sci-
Hutchings J.A. (1993) Adaptive life histories affected by age- ences 62, 738–746.
specific survival and growth rate. Ecology 74, 673–684. Stearns S.C. (1992) The Evolution of Life Histories. New
Mackereth R.W., Noakes D.L.G. & Ridgway M.S. (1999) York: Oxford University Press, 249 pp.
Size-based variation in somatic energy reserves and Steinhart G.B., Marschall E.A. & Stein R.A. (2004a) Round
parental care expenditure by male smallmouth bass, goby predation on smallmouth bass offspring in nests
Micropterus dolomieu. Environmental Biology of Fishes 56, during simulated catch-and-release angling. Transactions
263–275. of the American Fisheries Society 133, 121–131.
MacLean J.A., Shuter B.J., Reiger H.A. & MacLeod J.C. Steinhart G.B., Stein R.A. & Marschall E.A. (2004b) High
(1981) Temperature and year class strength of smallmouth growth rate of young-of-the-year smallmouth bass in Lake
bass. Proceedings of the symposium on early life history of Erie: a result of the round goby invasion? Journal of Great
fish. International Council for the Exploration of the Sea Lakes Research 30, 381–389.
178, 30–40. Steinhart G.B., Leonard N.J., Marschall E.A. & Stein R.A.
Martin N.V. & Fry F.E.J. (1973) Lake Opeongo: The Ecology (2005a) Effects of storms, anglers, and predators on
of the Fish Community and of ManÕs Effects on It. Ann smallmouth bass nest success. Canadian Journal of Fish-
Arbor, MI: Great Lakes Fishery Commission Technical eries and Aquatic Sciences 62, 2649–2660.
Report No. 24, 34 pp. Steinhart G.B., Sandrene M.E., Weaver S., Stein R.A. &
Mauck R.A., Marschall E.A. & Parker P.G. (1999) Adult Marschall E.A. (2005b) Increased parental care cost for
survival and imperfect assessment of parentage: effects on nest-guarding fish in a lake with hyperabundant nest pre-
male parenting decisions. The American Naturalist 154, dators. Behavioral Ecology 16, 427–434.
99–109. Steinhart G.B., Dunlop E.S., Ridgway M.S. & Marschall
Neff B.D. (2003) Decisions about parental care in response to E.A. (2008) Should I stay or should I go? Optimal parental
perceived paternity. Nature 422, 716–719. care decisions of a nest-guarding fish. Evolutionary Ecology
Olsen E.M., Heino M., Lilly G.R., Morgan M.J., Brattey J., Research 10, 351–371.
Ernande B. & Dieckmann U. (2004) Maturation trends Suski C.D. & Ridgway M.S. (2007) Climate and body size
indicative of rapid evolution proceeded the collapse of influence nest survival in a fish with parental care. Journal
northern cod. Nature 428, 932–935. of Animal Ecology 76, 730–739.
Petersen C.W. (1990) The occurrence and dynamics of clutch Suski C.D., Svec J.H., Ludden J.B., Phelan F.J.S. & Philipp
loss and filial cannibalism in two Caribbean damselfishes. D.P. (2003) The effect of catch-and-release angling on the
Journal of Experimental Marine Biology and Ecology 135, parental care behavior of male smallmouth bass. Trans-
113–133. actions of the American Fisheries Society 132, 210–218.
2010 Blackwell Publishing Ltd.VARIABILITY IN SMALLMOUTH BASS PARENTAL CARE 11 Székely T. & Cuthill I.C. (2000) Trade-off between mating Whitehead M.A., Schweitzer S.H. & Post W. (2000) Impact opportunities and parental care: brood desertion by female of brood parasitism on nest survival parameters and sea- Kentish plovers. Proceedings of the Royal Society of Lon- sonal fecundity of six songbird species in southeastern old- don, Series B: Biological Sciences 267, 2087–2092. field habitat. The Condor 102, 946–950. Tolonen P. & Korpimäki E. (1996) Do kestrels adjust their Wiegmann D.D., Baylis J.R. & Hoff M.H. (1992) Sexual parental effort to current or future benefit in a temporally selection and fitness variation in a population of small- varying environment? Ecoscience 3, 165–172. mouth bass, Micropterus dolomieui (Pisces: Centrarchi- Trivers R.L. (1972) Parental investment and sexual selection. dae). Evolution 46, 1740–1753. In: B. Campbell (ed.) Sexual Selection and the Descent of Williams G.C. (1966) Natural selection, costs of reproduc- Man, 1871–1971. Chicago, IL: Aldine Transaction, pp. tion, and a refinement of LackÕs principle. The American 136–207. Naturalist 100, 687–690. Walsh M.R., Much S.B., Chiba S. & Conover D.O. (2006) Yurewicz K.L. & Wilbur H.M. (2004) Resource availability Maladaptive changes in multiple traits caused by fishing: and costs of reproduction in the salamander Plethodon impediments to population recovery. Ecology Letters 9, cinereus. Copeia 2004, 28–36. 142–148. 2010 Blackwell Publishing Ltd.
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