Availability of Prey for Southern Resident Killer Whales

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Availability of Prey for Southern Resident Killer Whales
Availability of Prey for
Southern Resident Killer Whales
  Technical Workshop Proceedings
                       November 15-17, 2017

                    Editors: Andrew W. Trites
                            David A.S. Rosen

                                      Hosted by:

              Marine Mammal Research Unit
             Institute for the Oceans and Fisheries
                      University of British Columbia
                             Vancouver, BC, Canada
Availability of Prey for Southern Resident Killer Whales
Technical Workshop Proceedings
November 15–17, 2017
UBC Marine Mammal Research Unit

Editors: Andrew W. Trites
         David A.S. Rosen

These workshop proceedings should be cited as:

Trites, AW and Rosen, DAS (eds). 2018. Availability of Prey for
Southern Resident Killer Whales. Technical Workshop Proceedings.
November 15–17, 2017. Marine Mammal Research Unit, Institute for
the Oceans and Fisheries, University of British Columbia, Vancouver,
B.C., 64 pages

The information contained in this document is provided as a public
service. Although we endeavour to ensure that the information is as
accurate as possible, errors do occur. Therefore, we cannot
guarantee the accuracy of the information. It is important to note
that the opinions and suggestions contained in this document do not
necessarily reflect a consensus of every workshop participant, nor
the institutions or organizations they represent.

Cover image credit: Oil painting “Hide and Seek” by Bruce Muir (2017)

Marine Mammal Research Unit
Institute for the Oceans and Fisheries
University of British Columbia
Room 247, AERL, 2202 Main Mall
Vancouver, B.C. Canada V6T 1Z4

Tel.: (604) 822-8181
Email: mmru@oceans.ubc.ca
Web: www.mmru.ubc.ca

Availability of Prey for Southern Resident Killer Whales—Technical Workshop Proceedings 2018 • page 2
Table of Contents
Executive Summary ...................................................................................................................................... 4
Overview of Workshop ................................................................................................................................ 6
   Goals. ........................................................................................................................................................ 6
   Terminology.............................................................................................................................................. 6
   Assumptions & Limitations. ..................................................................................................................... 6
   Participants. .............................................................................................................................................. 6
   Proposed Management Actions. ............................................................................................................. 6
   Workshop Structure. ................................................................................................................................ 6
Summary of Discussions on Potential Management Actions ..................................................................... 7
   A: Increase abundance of Chinook coast-wide by reducing removals by fisheries ............................... 7
   B: Increase abundance of Chinook in specific-areas and times by adjusting removals by fisheries ..... 8
   C: Increase accessibility of Chinook by decreasing acoustic & physical disturbances ........................ 11
Conclusions ................................................................................................................................................. 13
   What Actions to Take ............................................................................................................................. 13
   Measuring Efficacy of Actions ................................................................................................................ 13
   Future Refinement and Planning ........................................................................................................... 14
Acknowledgements .................................................................................................................................... 14
Appendix A: Participants ............................................................................................................................ 15
Appendix B: Agenda ................................................................................................................................... 17
Appendix C: Participant Presentation Summaries ..................................................................................... 20
   Day 1 – Prey Requirements of Southern Resident Killer Whales (SRKW) ............................................... 20
   Day 2 – Availability of Chinook Salmon................................................................................................... 31
   Day 3 – Evaluation of Potential Mitigation Measures ............................................................................ 38
Appendix D: Management Action Tables ................................................................................................... 40
Appendix E: Table Definitions .................................................................................................................... 49
Appendix F: Notes from Group Discussions—Increase coast-wide Chinook abundance by reducing
fisheries ....................................................................................................................................................... 51
Appendix G: Notes from Group Discussions—Increase Chinook abundance at specific times and places55
Appendix H: Notes from Group Discussions—Increase Chinook accessibility at specific times ................ 60

Availability of Prey for Southern Resident Killer Whales—Technical Workshop Proceedings 2018 • page 3
Executive Summary                                     to implement this coast-wide action. The
                                                      scientific justification and confidence in this
This workshop assembled scientists and                action producing the desired benefits to SRKW
managers with technical expertise on killer           were ranked unknown or low.
whales and Chinook salmon to identify and
                                                      Action B. A more directed approach that evoked
evaluate short-term management actions that
                                                      greater scientific confidence was to limit
might increase the immediate abundance and
                                                      fisheries in times and places that correspond to
accessibility of Chinook salmon for southern
                                                      SRKW foraging activities. The assumption of this
resident killer whales, given the current size of
                                                      action is that limiting fishing where SRKW
Chinook salmon stocks. The workshop did not
                                                      normally feed would reduce direct competition
consider ways of producing more Chinook
                                                      with them, and increase their foraging success.
salmon (which will be the subject of a
                                                      Most of the vessels fishing within SRKW habitat
subsequent workshop), but rather considered
                                                      are recreational. While scientific confidence in
ways of making more of the fish that are
                                                      this action was greater than for the “blanket”
presently in the ocean available to southern
                                                      closures of fisheries throughout BC, there were
resident killer whales (SRKW).
                                                      still concerns about its potential effectiveness.
Workshop participants presented and discussed         Chief among these were uncertainties about
technical information on the prey requirements        how much prey are needed for SRKW to
of SRKW, the availability of Chinook salmon, and      successfully forage and meet their needs,
current protections for SRKW. Participants then       uncertainty in predicting foraging patterns and
split into four groups with an even distribution of   identifying which locations are most important,
expertise to review three potential non-              and whether partial or total fishery closures
exclusive Management Actions:                         within SRKW habitat would significantly increase
   A. Increase the abundance of Chinook for           the numbers of Chinook that SRKW could
      SRKW by reducing coast-wide fishery             capture. The scientific justification and
                                                      confidence in this action producing the desired
      removals.
                                                      benefits to SRKW were ranked low to medium.
   B. Increase the abundance of Chinook for
      SRKW by adjusting fishery removals at           Action C. This action was designed to increase
      specific times and in specific areas of         Chinook accessibility to SRKW by decreasing
      SRWK habitat.                                   acoustic and physical disturbance from vessels.
   C. Increase the accessibility of Chinook by        This action was considered and discussed in the
      decreasing underwater noise and the             context of all vessels—and not fishing vessels
      physical presence of vessels where SRKW         alone (which are believed to make up a relatively
      forage.                                         small portion of all the vessels encountered by
                                                      SRKW). Reducing incidences of disturbance can
Action A. One way to significantly increase the
                                                      be achieved by 1) excluding all vessels from
numbers of fish in SRKW habitat—and thereby
                                                      important SRKW habitat, and 2) implementing a
increase the foraging success of SRKW—might
                                                      200 m exclusion zone around SRKW. Such a
be to prevent fisheries from catching Chinook
                                                      protective bubble would limit how close vessels
earlier in their migration before they enter SRKW
                                                      could approach SRKW, but would not protect
foraging areas. However, there was considerable
                                                      whales if they chose to approach vessels within
uncertainty among workshop participants about
                                                      their habitat. The scientific justification and
the underlying theory and the practical capacity

Availability of Prey for Southern Resident Killer Whales—Technical Workshop Proceedings 2018 • page 4
confidence in this action producing the desired       Chinook can include improvement in body
benefits to SRKW were ranked medium to high.          condition of SRKW, increased use of foraging
                                                      areas, and less time travelling and feeding (and
Based on the current state of knowledge and
                                                      more time resting and socializing). However, use
best available data, workshop participants had
                                                      of these metrics requires a commitment to data
higher confidence in the effectiveness of Action
C (limiting vessel disturbances to make the           collection and analyses (and forethought into
Chinook that are already present easier for           how to interpret them) so that the effectiveness
SRKW to catch) than they did in increasing the        of the actions can be assessed and modified as
abundance of Chinook by closing or adjusting          necessary.
fisheries (Actions A & B).
                                                      This workshop was a first step in bringing
With >900 stocks of Chinook salmon migrating
                                                      together scientists and managers with killer
through BC waters at different times and
                                                      whale and Chinook salmon expertise from
strengths, there is currently insufficient evidence
to support being able to surgically manage            Canada and the United States to identify and
fisheries to avoid catching the stocks destined       evaluate short-term management actions that
for SRKW habitat. Nor is there evidence that          might be taken to increase the immediate
fishery reductions would add significant              abundance and accessibility of Chinook salmon
numbers to the estimated 600,000 Chinook              for SRKW, given the current size of Chinook
thought to currently move through inside waters       stocks. Going forward will likely require a
to Puget Sound and the Fraser River.                  smaller group of managers and scientists with
It will be critical to employ well-thought-out        expertise in killer whales and Chinook to develop
experimental designs that allow continual             detailed strategies, design the experimental
evaluation of the effectiveness of any                implementations, and identify the required
Management Action enacted. This is likely to be       analyses to ensure that any of the Management
important for the stakeholders and public             Actions undertaken are effective in improving
seeking reassurance that SRKW will realize the        the status and well-being of southern resident
full benefit of the intended action.                  killer whales.

Performance measures that can be used to
determine whether SRKW captured more

Availability of Prey for Southern Resident Killer Whales—Technical Workshop Proceedings 2018 • page 5
Overview of Workshop                                  actions regarding rebuilding Chinook stocks are
                                                      to be addressed in a future workshop. Thus, we
Goals. To identify short-term management              only considered short-term actions that could be
actions that might be taken to increase the           implemented through existing legislation and
immediate abundance and accessibility of              regulations.
Chinook salmon for southern resident killer
whales, given the current size of Chinook stocks.     Participants. Participants with technical know-
Thus, we evaluated short-term fishery                 ledge about killer whales, Chinook salmon, and
management actions that would provide                 fisheries management were invited from Canada
immediate benefits to southern resident killer        and the United States. These included 46
whales (SRKW). We did not consider ways of            individuals working for state and federal
producing more Chinook salmon, but rather             governments, consulting companies, nonprofit
considered ways of making more of the fish that       organizations, and universities (Appendix A).
are in the ocean available to SRKW to ultimately      Proposed Management Actions. Given the
increase the birth rates and decrease the death       afore-mentioned conditions, five potential (non-
rates of SRKW.                                        exclusive) Management Actions were developed
Terminology. “Availability” means being able to       in consultation with Fisheries and Oceans
be used or obtained. This term is used by some        Canada (DFO) and US National Marine Fisheries
to mean accessibility, while for others it reflects   Service (NMFS) biologists and managers.
the combination of both accessibility and             However, workshop participants proposed
abundance. We used this later definition when         facilitating discussions by grouping the five
referring to the availability (i.e., availability =   potential actions into these three:
abundance + accessibility) of prey for killer            A. Increase abundance of Chinook coast-wide
whales. “Accessibility” was defined as the ease             by reducing removals by fisheries.
of obtaining or using prey; and "abundance”              B. Increase abundance of Chinook in specific-
referred to the quantity or amount of Chinook               areas and times by adjusting removals by
salmon in areas where killer whales forage.                 fisheries.
Assumptions & Limitations. For the purposes of           C. Increase accessibility of Chinook by
attaining the goals of the workshop, we assumed             decreasing    acoustic    and      physical
that:                                                       disturbances.

   1. The SRKW population trajectory is in            The goal of these three Management Actions
      decline and will not improve under current      was to increase the short-term abundance or
      conditions.                                     accessibility of 4-5+ year old Chinook salmon in
                                                      areas where SRKW forage. SRKW consume
   2. The status of SRKW is related to the            Chinook 3+ years old, but prefer Chinook that are
      abundance and accessibility of Chinook          4 years and older.
      salmon.                                         Workshop Structure. On Days 1 and 2 of the
Workshop participants did not consider the            workshop, experts gave presentations in their
veracity of these assumptions, and focused            fields to inform the scientific validity of any of
instead on evaluating management actions that         the three potential management actions
could increase the abundance and accessibility        (Appendices B and C). Day 3 of the workshop was
of adult Chinook salmon (currently in the ocean)      dedicated to working in four groups to
within regions where SRKW forage. Potential           independently discuss the possible actions.

Availability of Prey for Southern Resident Killer Whales—Technical Workshop Proceedings 2018 • page 6
Discussions were guided by (but not limited to) a     would ultimately move “downstream” and enter
series of criteria developed in consultation with     areas where SRKW forage. Nor is it clear how
NMFS and DFO prior to the workshop (Appendix          many more fish might join those already moving
D).                                                   through key foraging areas used by SRKW as a
                                                      result of this action.
The overall goal was for workshop participants to
consider how the three actions could be               Based on the evidence presented at the
                                                      workshop, scientific confidence that this
implemented, and the likelihood that they would
                                                      Management Action was feasible or would
increase the abundance and accessibility of
                                                      provide the desired benefit to SRKWs was
Chinook for southern resident killer whales to        overwhelmingly low or unknown.
consume. While consensus building within
groups was desirable, care was taken to               The lack of endorsement for taking this action
document all opinions.                                was primarily due to:

                                                          Concern over being able to obtain real-time
                                                           scientific information on the movements of
Summary of Discussions on                                  different salmon stocks to implement
Potential Management Actions                               selective fishery reductions coast-wide;
                                                          Uncertainty concerning whether reducing
The following summaries reflect the discussions            catches in “distant” fisheries would increase
held on Day 3 of the workshop concerning each              the abundance of Chinook by enough to
of the Management Actions. Notes combining                 improve      SKRW        body     conditions.
information     transcribed   during     group             Mathematical models indicate that such an
discussions, and from tables filled out by                 action would not significantly increase the
workshop participants are contained in                     biomass of Chinook salmon for SRKW. This
Appendices F, G and H.                                     is partly based on the observation that
The summarized discussions that follow contain             some of the >900 Chinook salmon stocks in
1) the rationale underlying the three proposed             BC waters that are most prevalent in SRKW
Management Actions; 2) the scientific                      diets are also currently the most abundant
confidence of the workshop participants in the             Chinook runs.
feasibility of implementing each Management               A general consensus that fishery actions
Action, and whether it would provide the desired           that focus on key stocks targeted by SRKW
benefit to SRKWs; 3) associated uncertainties              would be more effective than general coast-
and unintended consequences associated with                wide fishery reductions. Key stocks thought
each action; and 4) ways in which the actions              to be most important to SRKW during spring
might be experimentally implemented to                     and summer are returning to Puget Sound
evaluate the effectiveness of each action, and             (pre-May and post-Aug), the Fraser River
refine them as necessary.                                  (May–Aug), lower southwest Vancouver
                                                           Island (Aug–Sep), and lower Strait of
                                                           Georgia (Aug–Sep). Puget Sound fish are
A: Increase abundance of Chinook coast-wide                present during summer, but in lower
   by reducing removals by fisheries                       proportions relative to Fraser Chinook.
Selectively reducing fishery catches (commercial          Uncertainty about how many more fish
and recreational) throughout British Columbia              SRKW need and could be provided by
would leave more fish in the ocean and thereby             reduced fisheries given that about 600,000
increase the abundance of Chinook. However, it             Chinook move through inside waters
is less certain which fish not taken by fisheries          (300,000 Fraser River and 300,000 Puget

Availability of Prey for Southern Resident Killer Whales—Technical Workshop Proceedings 2018 • page 7
Sound). Percentages of Fraser-bound fish               increase by initially consuming more
    caught before they enter the river is                  Chinook in terminal areas, and later preying
    relatively low for some stocks, such as the            on juvenile fish (in the case of seals)—with
    5-year-old spring and summer Chinook                   unintended impacts on overall Chinook
    (about 3–4%)—and higher for some 4-year                numbers.
    old fish (~25%).                                      And finally, there may be challenges for
    Recognition that not every fish saved from            international coordination, and impacts to
     fisheries will be available to SRKW due to            First Nations and Indian tribes.
     density dependent effects. It is not a linear
                                                      Despite these concerns, a few workshop
     relationship, as seen after 1990 when ocean
                                                      participants favoured this Management Action—
     fisheries were reduced in response to
                                                      on the premise that any precautionary measure
     declines of wild Chinook runs. Returns of
                                                      was worth implementing, despite it having a low
     some Chinook stocks increased following
                                                      probability of success.
     fishery restrictions, while others did not.
    Recognition that the percentage of spring        In contrast to this belief, most participants
     and summer Fraser Chinook caught in              agreed that implementing sweeping changes
     offshore mixed-stock commercial and              lacking scientific justification would ultimately
     recreational fisheries that are headed to        prove counterproductive to efforts to recover
     Juan de Fuca Strait is small.                    SRKW due to a lack of stakeholder and public
                                                      buy-in, and a potential perception that this
    Recognition that in-season adaptive
                                                      action was based on political rather than
     management would be difficult to
                                                      scientific considerations.
     implement to make this an effective action.
     It would likely be too late to close fisheries
     in-season by the time it was recognized that     B: Increase abundance of Chinook in specific-
     salmon numbers of particular stocks                  areas and times by adjusting removals by
     consumed by SRKW were low. Large                     fisheries
     offshore aggregate fisheries are managed
                                                      This Management Action is also designed to
     based on pre-season abundance forecasts
                                                      increase the abundance of 4-5+ year old Chinook
     of Canadian and US stocks in those fisheries.
                                                      salmon of key stocks — but within “core SRKW
     These forecasts are not updated in-season,
                                                      areas” at biologically appropriate times of the
     and would be challenging to do so until
                                                      year. In other words, to increase the abundance
     after fishing occurred.
                                                      of large Chinook salmon where and when SRKW
    Increased availability of Chinook resulting      are foraging.
     from fishery closures may be partially offset
     by removals by other predators (e.g.,            One means of increasing Chinook abundance
     NRKW). In other words, SRKW may not              during times that SRKW seek prey would be to
     consume the fish left by fisheries.              create refuges (or exclusion zones) over a
                                                      portion of SRKW critical habitat when SRKW are
    The possibility of other unintended
                                                      expected to be present. Operationally, this might
     consequences, whereby efforts to leave
                                                      be accomplished by imposing selective area
     more Chinook in the ocean might increase
                                                      closures during specific months, and
     the numbers of other consumers. For
                                                      redistributing fishing effort to places not used by
     example, NRKW might be the ultimate
                                                      SRKW. The period of highest recreational fishing
     beneficiaries of increased Chinook
                                                      use in Canada is from June to early September
     abundance—and might ultimately encroach
                                                      (Father’s Day to Labour Day).
     on SRKW habitat as their numbers increase.
     Similarly, seals and sea lions might also        Adjusting removals by fisheries in specific areas
                                                      used by SRKW at specific times of year was

Availability of Prey for Southern Resident Killer Whales—Technical Workshop Proceedings 2018 • page 8
considered to have more merit than coast-wide          There was some consensus that the abundance
fishery closures (Management Action A) for             of Chinook that occurred in previous “good”
several reasons. Most notably, adjusting fishing       SRKW years could provide a baseline measure of
effort by time and space is more likely to directly    what targeted abundance should be. However,
increase the abundance of Chinook for SRKW at          in the absence of this knowledge, it is unknown
specific times, and in specific areas where they       what level of increase or stability is required to
are likely to forage. It would avoid the “dilution”    measurably change SRKW condition or
effect of fishing in areas and at times “upstream”     demographics. Some predictive models indicate
of where SRKW forage.                                  a 30% rise in Chinook abundance is required—a
                                                       level approaching the “best” historic years—
In addition to an increased likelihood of
                                                       while other models indicate that a complete
providing greater benefits to SRKW, this type of
                                                       fishery closure would still be insufficient to
targeted fishery closure would likely have a
                                                       produce SRKW recovery, given the broad
lower socioeconomic impact than would broad
                                                       ecological and physical changes that have
(“upstream”) fisheries closures. Such an
                                                       occurred in the North Pacific Ocean.
approach would likely result in higher
stakeholder and public buy-in.                         Some uncertainty was also expressed in the
                                                       ability to identify which locations are most
An additional positive effect of selective fisheries
                                                       important, and what times of year are most
closures would be to alleviate potential physical
                                                       critical for SRKW.
and acoustic disturbance (see Management
Action C), although the ultimate benefit of this       In considering this action, it was generally felt it
would depend upon the proportion of fishing            should only be applied to:
vessels present relative to other vessels (which         1) Fisheries that catch a significant portion of
may be very low).                                           the key stocks of 4+ Chinook sought by SRKW
Despite having more merit than Management                   (e.g., those that catch >5% of returning fish);
Action A, workshop participants ranked their             2) Fisheries whose catches consist of a high
scientific certainty of the effectiveness of                proportion of 4+ year old Chinook (e.g., >10-
increasing Chinook numbers by adjusting fishery             20% of the fishery); and
removals within SRKW critical habitat to be low          3) Fisheries occurring within the time and high-
to medium. In general, the effectiveness of area-           use areas of SRKW foraging (based on field
based closures was ranked low, while the                    observations of SRKW).
effectiveness of maximum size limits on fish
                                                       For commercial fisheries, these actions would
caught was ranked higher.
                                                       apply to locations with the highest Chinook
The uncertainty expressed over implementing            catch. However, these areas are generally
this Management Action reflects several critical       outside (to the north) of SRKW range (with the
unknowns, such as how much prey are required           exception of Fishery Management Area 123).
for SRKW to meet their needs. It was unclear, for      Similarly, the critical time for closures would
example, what the desired abundance of specific        likely be during summer (but not exclusively)
Chinook stocks should be at specific times of          when the greatest numbers of Chinook are
year. Using current “conditions” as a baseline         caught.
was considered problematic because catches             Ideally, closures of commercial and recreational
and abundance are lower now than they have             fisheries would accommodate real time changes
been historically, while the number of other           in the presence and absence of foraging SRKW.
competing predators consuming Chinook                  However, differences in the spatial and temporal
(including NRKW) are higher.                           scale at which recreational and commercial
                                                       fisheries operate make it more difficult to
                                                       effectively adjust recreational fishery removals

Availability of Prey for Southern Resident Killer Whales—Technical Workshop Proceedings 2018 • page 9
of Chinook compared to adjusting commercial            During winter, J pod can be found foraging in the
fishery removals in real time. An action that          Strait of Georgia where Chinook winter
adapts to the daily movements of SRKW would            abundance has been high over recent years (and
likely be too difficult to effectively communicate     fishing effort low relative to summer months),
and logistically manage. The effectiveness of          suggesting that fishing limitations may have
such an action would also likely prove to be too       minimal additive benefit to J pod.
difficult to evaluate.
                                                       While fisheries might be adjusted to increase the
Additional questions were raised regarding how         quantity of Chinook available, they might also be
SRKW might react to partial closures within their      adjusted to increase the quality of individual
critical habitat. For example, would whales            Chinook consumed (through size-limits that
bypass areas where fishing was occurring and           leave bigger fish in the ocean). Body size of
concentrate foraging efforts in undisturbed            Chinook has become smaller over time, which
areas where abundance is theoretically higher?         means that each Chinook consumed by SRKW is
Similarly, would lots of Chinook in a noisy site       now providing fewer calories on average than it
with lots of vessel disturbance be as effectively      did in the past.
beneficial for SRKW as would feeding on a lower
                                                       Another point of consideration relates to the
abundance of Chinook in a quiet, undisturbed
                                                       predictability of foraging patterns of SRKW from
location? These questions highlight the
                                                       one year to the next. While SRKW are generally
considerable uncertainty about the relative
                                                       considered to be predictable in their annual
importance of Chinook abundance vs. the
                                                       movements, there can be considerable
accessibility of Chinook within an area. Killer
                                                       variability between years. Thus, the effective-
whales tend to spend a large proportion of time
                                                       ness of specific fishery closures under
in small areas, but it is unclear how big an area is
                                                       Management Action B is inherently limited by
required to be effective, or what degree of
                                                       the natural unpredictability of SRKW foraging
connectivity is needed between areas.
                                                       behaviour.
Field studies are planned to define SRKW
                                                       Given the foregoing uncertainties, workshop
foraging patterns and their relationship to
                                                       participants recognized that implementing this
fishing efforts. In the meanwhile, the picture is
                                                       (or any) Management Action must be done
far from clear.
                                                       experimentally (with a statistically appropriate
Implementing this Management Action would              experimental design), so that the effectiveness
be complex given that the three pods of the            of the action can be evaluated and adaptively
SRKW population (J, K and L) use different             changed as required. This would entail
foraging areas, and are not equally dependent          evaluating the effectiveness of specific closures
on the same Chinook stocks.                            on an ongoing basis, and suitably adjusting the
                                                       specific implementation of this Management
For example, K and L pods feed during winter off
                                                       Action as necessary. Specific monitoring would
the US west coast down to California. The stocks
                                                       be required to ascertain the effect of this action
important to these two pods vary in size and
                                                       on Chinook abundance and SRKW foraging
robustness (Klamath, Columbia, and coastal
                                                       behaviour within specific areas.
Chinook salmon stocks). The potential to
mitigate numbers of Chinook belonging to the           Determining whether restrictions placed on
different stocks through control of fisheries is       fishery catches have positive effects on SRKW is
also likely to prove unfeasible. It was noted, for     problematic. Determining whether foraging
example, that stocks in southern California are at     success improves will require concurrent studies
dire numbers, and there are few immediate              of salmon movements and SRKW foraging
options to revitalize these stocks, either through     efficiency (using longer-term observations and
fisheries management or other actions.                 underwater tracking technologies).

Availability of Prey for Southern Resident Killer Whales—Technical Workshop Proceedings 2018 • page 10
While the ultimate goal of this action is to          rates. This Management Action would
improve the population dynamics of SRKW by            specifically minimize acoustic interference with
increasing their birth rates and reducing death       echolocation during hunting and communication
rates, such measures of population recovery           between pod members, and would minimize
may respond on time scales that are too long to       physical interference from vessels that may
be linked to the proposed actions.                    disrupt surface chases, preclude prey sharing, or
                                                      cause animals to cease foraging and move out of
Estimates of SRKW body condition were
                                                      an area. One model suggests that increasing the
generally felt to be a more useful short-term
                                                      accessibility of Chinook salmon (i.e., the ability of
metric of nutritional status of individual whales,
                                                      SRKW to catch them) by 30-50% would
with the caveat that changes in physical
                                                      significantly improve the demographics of
condition can be caused by a number of factors
                                                      SRKW.
(such as disease) and are not necessarily
indicative of inadequate prey. Nevertheless,          This proposed action to minimize the negative
correlating metrics of SRKW health (body              effect of vessels on SRKW incorporates 1) vessel
condition, hormones) with salmon abundance            exclusion zones in key foraging areas (akin to
could help to identify when salmon abundance is       Management Action B), and 2) a protective
too low and fisheries need to be restricted.          exclusion zone around SRKW at all times.
Obtaining aerial images of SRKW returning in          Workshop participants recognized that it is
May, and again in the fall will provide essential     unrealistic to close all potential SRKW foraging
monitoring data on changes in body condition          areas at all times. However, they emphasized the
relative to the abundance of Chinook.                 need for quality data to make decisions about
                                                      which areas should be closed, and at which times
Implementing this Management Action would
                                                      of year to do so. Implementing this action
require continued studies of SRKW diet and
                                                      requires a rigorous experimental design to
foraging behaviour (times and locations) to
                                                      evaluate its effectiveness.
inform the management of key Chinook stocks
important to SRKW at the proper times of year.        It was further recognized that SRKW often forage
It would also require implementing an adaptive        in the presence of many vessels (recreational
management strategy, with annual evaluations          and commercial fishing, whale watching, and
of winter and summer SRKW distributions and           recreational vessel traffic). Given this overlap
stock-specific Chinook abundances.                    between vessels and SRKW, this action would be
                                                      minimally effective if it is only applied to fishing
                                                      vessels because numbers of fishing vessels are
C: Increase accessibility of Chinook by
                                                      believed to be relatively small compared to other
   decreasing acoustic & physical disturbances
                                                      types of vessels (although significant numbers of
Some workshop participants felt the accessibility     fishing vessels may gather in prime areas at
of Chinook in areas where SRKW forage would be        certain times). It is not clear how challenging it
significantly increased if 1) disturbances caused     might be to implement this action for different
by the presence of vessels was reduced by 50%,        classes of vessels from a regulatory view,
and if 2) disturbances caused by underwater           involving multiple legislative changes (i.e.,
noise from vessels were reduced by 100%. Other        Fisheries Act, Transport Canada, etc.).
workshop participants merely wanted significant
                                                      There was general consensus that a 200 m
reductions without specifying target levels.
                                                      exclusion zone was reasonable — despite the
Reducing the frequency of physical and acoustic
                                                      scientific questions surrounding the biological
disturbances would theoretically facilitate SRKW
                                                      effectiveness of this distance (a portion of the
being more successful at capturing prey—
                                                      participants suggested a more precautionary
thereby allowing them to be in better physical
                                                      400 m zone, but no one suggested a distance less
condition and have higher survival and birth

Availability of Prey for Southern Resident Killer Whales—Technical Workshop Proceedings 2018 • page 11
than 200 m, which is the approach distance              whales. Although whales might be expected to
currently required in the United States). This          avoid such noisy corridors and move to less
Action would theoretically provide “bubble”             disturbed areas, the presence of salmon may
protection around whales as they move into              motivate them to stay put.
known foraging areas.
                                                        Finally, while the intent of this Management
Unfortunately, building a moving bubble around          Action is to improve the foraging of SRKW by
SRKW has its limitations, even when perfectly           making it easier for SRKW to catch the fish that
implemented. For example, it would not prevent          are present, it would likely have to be
whales from moving into a foraging area where           implemented for all killer whales (transient and
vessels are already present. While regulations          resident) because it is unrealistic to expect
would prevent approaching the whales closer             operators to readily distinguish between the two
than 200 m, it cannot legislate against whales          ecotypes of killer whales.
moving towards vessels and exposing
                                                        Workshop participants ranked the scientific
themselves to vessel noise and movements that
                                                        certainty that reducing physical and acoustic
may degrade their foraging environment. Nor
                                                        disturbances by vessels would significantly
would operators necessarily be required to limit
                                                        increase the accessibility of Chinook for SRKW as
their acoustic footprint if they are already in the
                                                        medium to high.
area.
                                                        This range in certainty is higher than the other
One means of reducing the potential for vessels
                                                        two Management Actions considered, and
to affect the ability of SRKW to access Chinook
                                                        reflects the extent and importance of knowledge
would be to require them to pull their gear and
                                                        gaps. While there was an accepted link between
turn off their fish finders or engines (if safe to do
                                                        noise and poor foraging success, the dose-
so) should whales approach within a specified
                                                        response of SRKW foraging behaviour in relation
distance within identified foraging areas. Speed
                                                        to vessel noise and numbers was less clear.
restrictions could also be implemented within
                                                        Other identified potential knowledge gaps
critical foraging areas used by SRKW.
                                                        include sound profiles of critical areas, and
As a side note, it was mentioned that the               diurnal pattern of SRKW foraging. It was felt that
majority of recreational Fishfinders operate at         these questions could be clarified through
two frequencies (50 and 200 kHz), and are preset        further studies, while the exclusion zone should
to the lower frequency that has a broader and           be experimentally implemented. Despite these
deeper cone of ultrasound coverage than the             gaps, vessel exclusion zones were generally felt
higher frequency. The hearing range of killer           to be a prudent measure.
whales extends from ~0.6 KHz to >100 kHz, with
                                                        The efficacy and design of exclusion zones can
the greatest sensitivity between 20–50 kHz. To
                                                        only be improved through intensive monitoring
avoid potential impacts within the hearing range
                                                        during implementation. Operator compliance
of SRKW, manufacturers or users could preset
                                                        evaluations could include AIS (Automatic
their devices to the higher 200 kHz frequency to
                                                        Identification System) monitoring, cameras and
prevent overlap with the SRKW dynamic range,
                                                        radar. As has been demonstrated in other
and users could be educated about using the
                                                        marine programs, education of vessel operators
higher setting around whales.
                                                        (particularly recreational) is often as important
Mediating vessel behaviour when killer whales           as regulatory enforcement. Specific guidance
approach them is particularly problematic in            would also likely be required for those fishing
transportation corridors within SRKW critical           (target messaging in key areas such as Salmon
habitat that have high numbers of moving                Bank), and perhaps as part of licensing
vessels. Under such circumstances, there seems          procedures.
little chance of creating a “quiet zone” for the

Availability of Prey for Southern Resident Killer Whales—Technical Workshop Proceedings 2018 • page 12
The biological effectiveness of this action on        significantly increase the ability of SRKW to catch
SRKW would have to be closely monitored.              the salmon that are present in foraging areas.
While this action is likely to improve targeted
foraging opportunities for SRKW, it is unclear        Measuring Efficacy of Actions
what effect it will have on their well-being.
                                                      There are a number of performance measures
Evaluating the efficacy should include potential
                                                      that can be used to assess the effectiveness of
short-term effects such as behavioural measures
(e.g., the amount of time whales spend in             Management Actions on SRKW. However, each
feeding areas), the acoustic levels within those      requires a commitment to data collection and
areas, and an analysis of foraging success vs.        analyses, and forethought about how to
acoustic profiles, and longer-term studies on         interpret them. Possible metrics include:
changes in physical condition and hormone
                                                      Body Condition. Aerial photographs of SRKW
profiles of SRKW.
                                                      retuning in May, and again in the fall will provide
In addition to implementing an experimental           essential monitoring data on changes in body
framework to evaluate the benefit of areas of         condition relative to the abundance and
action versus no action, restricting the              accessibility of Chinook during spring and
movement and presence of vessels should be            summer, as well as relative measures of feeding
done adaptively. This would entail establishing
                                                      conditions during winter when the SRKW are
connections between SRKW health and Chinook
                                                      believed to be primarily along the outer coast of
abundance (e.g., scenarios indicate suite of
options for high Chinook/low whale condition,         the United States. An invaluable database of
low Chinook, etc.).                                   body conditions has grown in recent years, but is
                                                      not yet sufficient to determine an ideal body
                                                      condition or what a significant improvement
Conclusions                                           looks like.
What Actions to Take
The four discussion groups had evenly balanced        Table 1. Scientific justifiability of the Management
expertise on killer whales, Chinook salmon and        Actions and the likelihood that they would provide
fisheries management — and came to similar            the desired benefit to SRKWs. Note that the
conclusions about the scientific justifiability of    likelihood of success correlated positively with
the Management Actions considered, and the            scientific justification — “?” represents unknown.
likelihood that they would provide the desired                                    Scientific Justifiability
                                                        Management Action
benefit to SRKWs (Table 1).                                                       ?   Low Med High
Overall, there was little confidence (unknown–         A. Increase abundance
low) that reducing fishery catches coast-wide          of Chinook coast-wide
                                                                                  X     X
                                                       by reducing removals
would benefit SRKW, and slightly more
                                                       by fisheries
confidence (low–med) that restricting catches
                                                       B. Increase abundance
within specific areas of SRKW critical habitat
                                                       of Chinook in specific-
would significantly increase Chinook abundance.                                         X       X
                                                       areas & times by adjust-
                                                       ing fishery removals
In contrast to doubts about being able to
significantly increase the numbers of fish in          C. Increase accessibil-
SRKW habitat, there was greater confidence             ity of Chinook by
                                                                                                X      X
                                                       decreasing acoustic &
(med–high) that reducing acoustic noise and            physical disturbances
physical disturbances by vessels would

Availability of Prey for Southern Resident Killer Whales—Technical Workshop Proceedings 2018 • page 13
Physiological Status. Significant advances have        interval between calving times, increasing
been made in developing ways to assess the             success at age of first reproduction, and
well-being of free-swimming whales. Fecal              increasing reproductive potential (improved age
samples, respiratory (blow) samples, blubber           & sex composition of pods). However, changes in
biopsies, and skin samples are increasingly used       reproduction and survival rates occur over
to assess health, nutritional status, exposure to      relatively long periods and are unlikely to be
disease, stress levels, and reproductive status.       useful or dependable measures of the
Validation of methodologies to assess and              immediate effects of the actions considered.
interpret physiological status relative to
environmental conditions (i.e., perceived              Future Refinement and Planning
stressors) is ongoing.                                 This workshop was an important first step in
Area Use. The percentage of time a whale               bringing fisheries managers and killer whale and
spends in particular areas is likely to be a useful    Chinook salmon experts together to identify and
metric. This is based on the assumption that           evaluate short-term management actions that
more time moving between areas is indicative of        might be taken to increase the immediate
lower available prey—while less travelling is          abundance and accessibility of Chinook salmon
presumed to reflect relatively good foraging.          for SRKW, given the current size of Chinook
                                                       stocks.
Activity Budgets. The percentage of time killer
whales engage in resting, foraging, travelling,        As a next step, a smaller group of managers and
and socializing is presumed to reflect feeding         scientists with expertise in killer whales and
conditions—as it has been observed that killer         Chinook could develop detailed strategies,
whales typically travel more and forage less in        design the experimental implementations and
bad salmon years and in the presence of vessels        required analyses to ensure the effectiveness of
(they also tend to do less resting and socializing).   the actions taken to improve the status of
                                                       southern resident killer whales.
Acoustic Behaviour. Foraging activity could be
captured by hydrophones. Changes in the
frequency of calls between SRKW might reflect
changes in feeding conditions.
                                                       Acknowledgements
                                                       The workshop was supported through Fisheries
Foraging Success. Individual SRKW might be             and Oceans Canada’s Ocean and Freshwater
followed from shore or from a distance on the          Science Contribution Program awarded to
water to document successful prey captures.            Andrew Trites and Brian Hunt at the UBC
Suction-cup electronic tags that record                Institute for the Oceans and Fisheries. We are
underwater behaviours can be attached for brief        grateful for the logistical support provided by
periods to determine where, when and how               Pamela Rosenbaum (UBC Marine Mammal
frequently SRKW catch Chinook and whether              Research Unit), and for the rapporteur support
they    are   more     successful    following         from Madeline Young (International Year of the
implementation of the Management Action.               Salmon). We are also grateful to Earth and
Reproduction & Survival. The overall goal of all       Oceans Sciences, and to the Institute for the
the Management Actions considered during this          Oceans and Fisheries for providing meeting
workshop was to support SRKW recovery by               rooms.
ultimately increasing the number of female
calves, increasing calf survival, reducing the

Availability of Prey for Southern Resident Killer Whales—Technical Workshop Proceedings 2018 • page 14
Appendix A: Participants

Lynne Barre              US National Marine Fisheries Service     lynne.barre@noaa.gov

Lance Barrett-Lennard    Ocean Wise                               lance.barrett-lennard@ocean.org

Penny Becker             Washington Dept of Fish and Wildlife     penny.becker@dfw.wa.gov

Gayle Brown              Fisheries and Oceans Canada              gayle.brown@dfo-mpo.gc.ca

Sean Cox                 Simon Fraser University                  sean_cox@sfu.ca

Thomas Doniol-Valcroze Fisheries and Oceans Canada                thomas.doniol-valcroze@dfo-
                                                                  mpo.gc.ca

John Durban              US National Marine Fisheries Service     john.durban@noaa.gov

Peter Dygert             US National Marine Fisheries Service     peter.dygert@noaa.gov

Holly Fearnbach          SR3                                      hfearnbach@sealifer3.org

Mike Ford                US National Marine Fisheries Service     mike.ford@noaa.gov

John Ford                University of British Columbia           john.ford@ubc.ca

Jeff Grout               Fisheries and Oceans Canada              jeff.grout@dfo-mpo.gc.ca

Brad Hanson              US National Marine Fisheries Service     brad.hanson@noaa.gov

Marla Holt               US National Marine Fisheries Service     marla.holt@noaa.gov

Kirt Hughes              Washington Dept of Fish and Wildlife     kirt.hughes@dfw.wa.gov

Brian Hunt               University of British Columbia           b.hunt@oceans.ubc.ca

Lisa Jones               Fisheries and Oceans Canada              lisaann.jones@dfo-mpo.gc.ca

Chris James              NW Indian Fisheries Commission           cjames@nwifc.org

Ruth Joy                 SMRU Consulting                          rj@smruconsulting.com

Peter Katinic            Fisheries and Oceans Canada              peter.katinic@dfo-mpo.gc.ca

Robert Kope              US National Marine Fisheries Service     robert.kope@noaa.gov

Karen Leslie             Fisheries and Oceans Canada              karen.leslie@dfo-mpo.gc.ca

Wilf Luedke              Fisheries and Oceans Canada              wilf.luedke@dfo-mpo.gc.ca

Marla Maxwell            Fisheries and Oceans Canada              marla.maxwell@dfo-mpo.gc.ca

Teresa Mongillo          US National Marine Fisheries Service     teresa.mongillo@noaa.gov

Jennifer Nener           Fisheries and Oceans Canada              jennifer.nener@dfo-mpo.gc.ca

Dawn Noren               US National Marine Fisheries Service     dawn.noren@noaa.gov

Availability of Prey for Southern Resident Killer Whales—Technical Workshop Proceedings 2018 • page 15
Jan Ohlberger            University of Washington                 janohl@uw.edu

Martin Paish             Sport Fishing Institute of BC            mpaish@sportfishing.bc.ca

Brian Riddell            Pacific Salmon Foundation                briddell@psf.ca

David Rosen              University of British Columbia           rosen@zoology.ubc.ca

Teresa Ryan              University of British Columbia           teresa.ryan@ubc.ca

Bryan Rusch              Fisheries and Oceans Canada              bryan.rusch@dfo-mpo.gc.ca

Mei Sato                 Oregon State University                  msato@coas.oregonstate.edu

Mark Saunders            International Year of the Salmon         msaunders@yearofthesalmon.org

Sharlene Shaikh          Fisheries and Oceans Canada              sharlene.shaikh@dfo-mpo.gc.ca

Eva Stredulinsky         Fisheries and Oceans Canada              estredulinsky@gmail.com

Jennifer Tennessen       US National Marine Fisheries Service     jennifer.tennessen@noaa.gov

Mary Thiess              Fisheries and Oceans Canada              mary.thiess@dfo-mpo.gc.ca

Sheila Thornton          Fisheries and Oceans Canada              sheila.thornton@dfo-mpo.gc.ca

Andrew Trites            University of British Columbia           a.trites@oceans.ubc.ca

Bob Turner               US National Marine Fisheries Service     bob.turner@noaa.gov

Eric Ward                US National Marine Fisheries Service     eric.ward@noaa.gov

Rob Williams             Oceans Initiative                        rob@oceansinitiative.org

Brianna Wright           Fisheries and Oceans Canada              brianna.wright@dfo-mpo.gc.ca

Madeline Young           International Year of the Salmon         myoung@yearofthesalmon.org

Availability of Prey for Southern Resident Killer Whales—Technical Workshop Proceedings 2018 • page 16
Appendix B: Agenda

Availability of Prey for Southern Resident Killer Whales—Technical Workshop Proceedings 2018 • page 17
Availability of Prey for Southern Resident Killer Whales—Technical Workshop Proceedings 2018 • page 18
Availability of Prey for Southern Resident Killer Whales—Technical Workshop Proceedings 2018 • page 19
Appendix C: Participant Presentation Summaries
The following synopses of workshop presentations were provided by participants, and have been
edited for style.

November 15, 2017                                             1. High proportions of physically mature
Day 1 – Prey Requirements of Southern                            males &/or lactating females in the
Resident Killer Whales (SRKW)                                    groups      (i.e.   nutritionally-needy
                                                                 individuals)
A. SRKW status and demographic update (Eric
   Ward, NWFSC)                                               2. Leadership capacity within the group
    SRKW are likely to continue to decline.                     (i.e. multiple old, mature females)
     How quickly that happens depends on                      3. Lower maternal relatedness among
     what assumptions we make about future                       group members (this can occur
     environmental conditions, sex ratios at                     through deaths of common ancestors
     birth being different from 50:50, potential                 as well as group growth)
     effects of inbreeding, and other factors                Prey sharing is a prevalent behaviour in
     that reduce fecundity or survival.                       RKWs, where animals share prey with
    SRKW are an anomaly in that they are the                 their closest maternal relatives
     only killer whale population in the NE                   - Adult RKW females are the primary
     Pacific that hasn't increased exponentially.               provisioners of their groups, sharing
     This is true since the 1970s, including the                consistently even in years of low
     period since the last 2011-2012
                                                                salmon abundance (which makes
     workshops.
                                                                them particularly vulnerable to food
    As noted in the last independent panel
                                                                shortages).
     report and work since, there is increased
                                                              - Adult males share the least with their
     opportunity for competitive effects of
     other killer whale populations on SRKW                     group. This is likely because they have
     (NRKW in particular have spatial overlap                   huge caloric requirements and they
     with SRKW).                                                are also the least maternally related
    Recent trends in SRKW appear to be                         (on average) to their group.
     somewhat decoupled from aggregate                       While a mother’s provisioning of her
     salmon indices. In the last 5-10 years,                  daughters       stops     at    daughter’s
     salmon indices have been at or near                      reproductive maturity, sons are
     historic highs and these periods have seen               provisioned throughout their lifetime
     high population growth of other killer                   - Adult males depend on close female
     whales. But the trajectory for SRKW is                     relatives to be provisioned, and, in the
     somewhat opposite.                                         absence of such relatives, their
                                                                survival decreases. This relationship is
B. Influence of sociality on the prey needs of                  especially apparent in years of low
   Southern Resident Killer Whales (Eva                         salmon abundance.
   Stredulinsky, DFO)
                                                             Relevant notes from outside of this
     Splitting of RKW groups is correlated to                presentation:
      coast-wide Chinook abundance                            - According to SRKW photogrammetry
     This relationship is amplified by:                        work (J. Durban, H. Fearnbach et al.),
                                                                while adult males have females

Availability of Prey for Southern Resident Killer Whales—Technical Workshop Proceedings 2018 • page 20
provisioning them, they consistently         D. Coastal occurrence of SRKWs based on
         have the best body condition of all             sightings and acoustic data (Ruth Joy, SMRU
         age-sex classes. So it seems, in                Consulting)
         general, they are only vulnerable to             Project goals
         food shortages when they are lacking             1. To better understand the fine-scale
         older female animals to provision                   spatial and temporal distribution of
         them.                                               SRKW during “Chinook season” (May-
                                                             October), focusing on current and
C. Killer whale genetics, and paternity in the               proposed Canadian Critical Habitat.
   southern resident population (Michael                  2. To better understand where foraging
   Ford, NOAA)                                               occurs.
   Main points                                             Multiple datasets: some opportunistic
     The whales have highly skewed male                    presence only, some more systematic with
      reproductive success – ~50% of the                    associated effort.
      current population descended from just               One of the key datasets was collected by
      two males                                             Brian Gisborne with 2887 tracklines of
     Four apparent cases of close inbreeding               effort distributed across 815 days. He
      (2.5% of all inferred matings)                        observed SRKW 158 times across effort
     Less close inbreeding is certainly                    mostly       concentrated       in      the
      occurring, but hard to detect with                    spring/summer/fall months.
      current data                                         The 2nd key source of data is that from the
                                                            BCCSN and OrcaMaster datasets. These
     Consequences of inbreeding in the
                                                            are presence only datasets for which we
      population still under study - will have
                                                            will have to derive either a pseudo effort
      results next year
                                                            datalayer from absence data, or else a
     No evidence of inbreeding avoidance                   presence only approach. We’d like to
     Population has had low effective size                 avoid making assumptions about ‘effort’.
      (~25) for at least several generations               The overarching methodological plan is to
   Implications for prey conservation/use                   fit a Bayesian spatial-temporal model
      Old, large males are important and they              using approximate methods (instead of
       need a lot of food, but the population               particle MCMC) to estimate the
                                                            probability of SRKW presence in the Salish
       may not need very many of them
                                                            Sea in the months from May to October.
      Inbreeding depression may mean
                                                            We will be incorporating as much data as
       population needs more prey than a
                                                            we can (scared about the Chinook data
       comparable outbred population                        now though!!), with the intent to start
      Based on the work by Eva Stredulinksy,               with integrating Brian’s data with the
       the whales seem to put a lot of resources            sightings databases.
       into males, and this seems almost                   Deliverable date is March 2018.
       maladaptive from a population
       perspective even if it perhaps makes
       sense from an individual whale
       perspective

Availability of Prey for Southern Resident Killer Whales—Technical Workshop Proceedings 2018 • page 21
E. Coastal occurrence of southern resident            G. Dtags as a tool for behavioural studies of
   killer whales based on satellite tagging and          resident killer whales (Brianna Wright,
   acoustic recorder detections (Brad Hanson,            DFO)
   NWFSC)
                                                          See: Wright, B.M., Ford, J.K.B., Ellis, G.E.,
    Acoustic recorder detections and satellite-          Deecke, V.B., Shapiro, A.D., Battaile, B.C. &
     linked tag location data from SRKW have              Trites, A.W. 2017. Fine-scale foraging
     provided a much more complete picture of             movements by fish-eating killer whales
     SRKW fall, winter, and spring occurrence             (Orcinus orca) relate to the vertical
    Acoustic recorder detection data showed              distributions and escape responses of
     that the area near the Columbia River was            salmonid prey (Oncorhynchus spp.).
     used much more than expected by K/L                  Movement Ecology 5:3.
     pods
    Satellite tagged members of K and L pods         H. Acoustic cues recorded from animal-borne
     ranged from Cape Flattery, Washington to            tags to quantify foraging events in
     Pt. Reyes, California, remaining on the             endangered fish-eating killer whales (Marla
     continental shelf, and generally close to           Holt, NWFSC)
     the coast                                             34% of dives contained echolocation click
    High use sites for K/L pods included areas             bouts
     off the Columbia River and Gray’s Harbor,             The majority of click bouts were slow
     northern California, and the northern                  clicks on repeated shallow dives,
     Olympic Peninsula                                      interpreted as searching for prey at the
    K/L pods primarily occur in a relatively               surface. This makes SRKW vulnerable to
     narrow band of the continental shelf near              vessel masking noise and boat presence
     the coast                                             Dive depth and year were important
    Satellite tagged members of J pod ranged               explanatory variables of click presence
     from the continental shelf waters of the              Co-occurrence of buzzes and prey
     central west coast of Vancouver Island to              handling sounds indicate prey capture
     northern Georgia Strait                               Males had higher presence of buzz and
    High use sites for J pod included northern             prey handling sounds on per dive basis,
     Georgia Strait and the western end of Juan             consistent with having higher feeding
     de Fuca Strait                                         rates to support a larger total body size
    K/L and J pods appear to have nearly                  Integration of the acoustic data analysis
     exclusively separate winter ranges                     results with other tag sensor data is
    In general, SRKWs appear to display                    critical input for the development of the
     similar range and site fidelity patterns               foraging detector, presented by J.
     between years                                          Tennessen
                                                           Results ultimately will be used to predict
                                                            foraging in order to determine vessel and
F. Assessment of potentially important SRKW
   habitat outside of designated Critical                   noise effects on behavior, including
   Habitat (John Ford, DFO & UBC)                           different phases of foraging that involve
                                                            the use of sound
   No summary provided

Availability of Prey for Southern Resident Killer Whales—Technical Workshop Proceedings 2018 • page 22
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