AFS Ottawa

I recently returned from a week-long trip to the American Fisheries Society annual conference in Ottawa, Ontario. This year’s theme was “Fisheries in Flux: How Do We Ensure Our Sustainable Future,” and I presented my work in the symposium entitled “Tagging and its Use in Stock Assessment.” There were 35 symposia, which led to endless topics and case studies on species and systems ranging from tiny darters in mountain streams to pelagic tuna in the Atlantic. Needless to say, it was a great place for a “fish nerd” to “dork out.”

The tagging symposium was extremely informative and engaging. Tagging data can be used to inform stock assessments from many angles, most notably mortality estimates, exchange between stocks, and abundance estimates. We saw a wide range of use of tagging data in all of these categories and more. Discussions were helpful and collaborations were formed. I presented the methodology for my yellowtail flounder Petersen tagging experiment (abstract below) and received a bevy of good questions and suggestions (and some critique). It was an excellent experience, and I was very happy with my talk and proud of the presentations given by my colleagues at SMAST and NOAA Fisheries.

Ottawa is a beautiful city, and we were stationed right next to Canada’s Parliament and the Byward Market. Many delicious drinks, snacks and meals were consumed in the latter. The conference’s “signature” Wednesday night social was held at the Canadian Museum of Civilization in Gatineau, Quebec. It was an architecturally unique and beautiful building that housed many artifacts and interpretive exhibits on Canada’s history. A fitting site for so many self-proclaimed dorks, and there were many fishing exhibits on hand to indulge our curiosities on Canada’s maritime history.

I now get back to work on my data processing and prepare for classes to start next week. I will be taking one course (Geostatistics for Fisheries Applications) and preparing for my next conference, the International Flatfish Symposium in Sesimbra, Portugal in November.

Abstract: Yellowtail flounder on Georges Bank are currently considered overfished. Management of the stock is based on quotas, and where the stock overlaps with other commercially-important stocks – for example, scallops – an economic loss may occur when the total allowable catch (TAC) quota is reached via bycatch of the species and the fishery is shut down. Currently, uncertainty exists in the Georges Bank yellowtail stock assessment. A Petersen mark-recapture experiment is being used to provide an estimate of yellowtail flounder abundance and spatial distribution in ‘Closed Area II’ on Georges Bank which will supplement the conventional stock assessment. The Petersen method is a single recapture event model in which the following assumptions are made: the population is closed, samples are random, marked animals are representative of the population, marks are not lost between capture and recapture events, and all recaptures are reported. Model estimates of abundance and variance as well as adherence to assumptions will be evaluated from the data, along with spatial analysis and investigation into length, age, and maturity structure of the population. Few Petersen studies have been conducted in the open ocean environment, so testing the closure assumption will be very important in order to determine the validity of the model on this spatial and temporal scale. The tagging experiment is planned to be conducted over approximately 10 days, on four vessels, with a total of 100,000 tags applied at random sample stations in the study area. Random tows to sample the population for the proportion tagged will be made in the final three days of the study. The estimate of abundance will be completed shortly thereafter, with analysis of assumptions and spatial distribution occurring in the fall.

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This is an article that was posted on Aug 25, 06:16 PM.

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