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Status of Stocks & Multispecies Assessment Program

AFSC Hosts Pacific Cod Technical Workshop

At the request of the Scientific and Statistical Committee (SSC) of the NPFMC, the AFSC convened a public workshop to examine various technical issues pertaining to the assessments for Pacific cod in the Bering Sea (BS), Aleutian Islands, and Gulf of Alaska (GOA). The workshop took place at the Seattle offices of the AFSC over a 2-day period, from Tuesday, 24 April through Wednesday, 25 April 2007. SSC chair and REFM Division director Pat Livingston served as chair of the workshop and Liz Conners served as rapporteur. A total of 44 people attended the workshop, reflecting participation from various government agencies, universities, fishing industry groups, and consulting firms.

Tuesday morning’s session consisted of six presentations by AFSC and other scientists involved in Pacific cod research. These were as follows:

  • Dave Somerton and Dan Nichol (AFSC): Survey catchability/availability
  • Bing Shi (AFSC): Estimation of movement and survival rates from tagging data
  • Kerim Aydin (AFSC): Can ecosystem models provide a prior distribution for M?
  • Olav Ormseth (AFSC): Reproductive potential and egg quality: area and maternal effects
  • Doug Kinzey (Univ. Washington): Multispecies Aleutian Islands assessment model
  • Delsa Anderl (AFSC): Ageing issues and progress

Tuesday afternoon’s session began with two more presentations by AFSC scientists, with Jim Ianelli discussing fishery and catch sampling issues and Grant Thompson reporting on modeling issues and progress. The latter presentation addressed several suggestions made by the SSC involving estimation of growth parameters, the natural mortality rate, the trawl survey catchability coefficient, and survey and fishery selectivity schedules. Detailed results were presented for a total of 16 models configured separately for both the BS and GOA, plus another 6 models configured for the BS only. Tuesday afternoon’s session concluded with an open discussion which generated suggestions for 10 additional model runs to be made that evening.

The Wednesday morning session began with a free-form discussion regarding the feasibility of a dedicated Pacific cod longline survey. This discussion also addressed the possibility of using data on Pacific cod taken as bycatch in the existing longline survey conducted by the International Pacific Halibut Commission. The Wednesday morning session concluded with a presentation and discussion of results from the model runs made the previous evening.

Wednesday afternoon’s session began with a general discussion related to modeling issues. The session concluded with an opportunity for all participants to make suggestions for this year’s stock assessments. A detailed summary of the entire workshop, including the list of suggestions for this year’s assessments, can be accessed online at:  (506KB).

By Grant Thompson

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