Steller Sea Lion Modeling Workshop

Workshop participants, from left to right:  Bern Megrey (AFSC), Ian Boyd (SMRU), Brian Fadely (NMML),Carlos Alvarez (AFSC), Sasha Dall (Cambridge Univ.), Anne York (NMML), Jeremy Sterling (NMML), Julian Burgos (UW), Martin Dorn (AFSC), Sarah Hinckley (AFSC), Tiffany Vance (AFSC), John Horne (UW/AFSC), Dawn Noren (NMML), Lowell Fritz (AFSC), Dave Thompson (SMRU), Michelle Lander (UW/NMML), Tom Loughlin (NMML).

A workshop on modeling Steller sea lion (SSL) foraging, bioenergetics, and population dynamics was held at the Aljoya Conference Center in Seattle on 24-25 September 2002.   Attendees of the conference were members of the Alaska Fisheries Science Center (AFSC) SSL modeling team, members of the Sea Mammal Research Unit (SMRU, St-Andrews University, Scotland) modeling team, and others from the AFSC, National Marine Mammal Lab (NMML) and University of Washington interested in this subject.

The objectives of the workshop were to 1) review the range of potential bioenergetics and foraging behavior models that could be applied to Steller sea lions, 2) examine the extent to which these models are being researched to address important management issues for SSLs, 3) discuss the current research and report progress and potential areas of difficulties, and 4) encourage the development of synergistic links between different groups researching bioenergetics and foraging behavior in SSLs.  Workshop participants saw a compelling need to encourage communication between modelers of SSLs in order to prevent overlap of models, encourage complementary modeling approaches and collaborations, facilitate the use of common information to develop these models, and ensure that models developed are appropriate to the goals of the project. It was noted that  the SSL modeling work undertaken by various researchers should meet the needs of those who must manage this endangered species.

The first day, Sea Lion-Groundfish Coordinator Lowell Fritz gave an introduction to the problem and background information on the SSL decline and discussed potential effects of fisheries on prey availability.  Workshop participants then gave presentations on the models they are working on and some new research and data.  At the end of the day, a short summary was given, with discussion of the major issues that were brought up.  It appeared that similar modeling issues came up for both the AFSC SSL modeling group and the SMRU modeling group, however analytical approaches differed.  A generalized flow chart of the models and their connection was proposed:

It was noted that most of the work of the two modeling groups focused on the prey field/foraging success area.  A particular gap in the modeling work was identified as the life-history decision process area.

Several more presentations were given the following day.   After the presentations, discussions focused on several overarching questions but was wide ranging on these and other topics.  Areas of discussion included, “What are the central questions we are trying to address with our models?”, “How can these be approached from a modeling perspective?”,  “What are the criteria for model selection?”, “What time and space scales are important?”, “Is location specificity important?” and “How do we coordinate our efforts and make our modeling work complementary?”.

Workshop participants compiled a list of recommendations, including  forming a Working Group, with Sarah Hinckley as coordinator; setting up a web page for working group members for information exchange and coordination;  the decision that the east Kodiak region should be the test region for the models; the decision that both groups (AFSC, SMRU) should use a common bioenergetic model and that both groups should use common prey fields generated by the dynamic pollock model under development, and others.  An action plan and task list was also developed, which included time frames and dates for various products and meetings, with individuals identified for each task.

The workshop was very successful in facilitating the exchange of information between these two modeling groups and others, and identifying common problems and their potential solutions.  Areas of future individual and group collaborations, and gaps in the modeling work (and ideas to rectify these) were identified.  Plans were made to make available model code, descriptions, and documentation to facilitate intergroup communications.  The working group is intended to continue this productive interchange and facilitate future collaborations.