Thesis Update

In early June I completed a 10-day Petersen Tagging Experiment in Closed Area II on Georges Bank in the Western Atlantic. The experiment was conducted on yellowtail flounder, a species of great commercial interest. The stock in this area has been estimated using several models which produce conflicting results. This experiment was designed to elucidate some of this conflict by giving an abundance estimate in the closed area.

The experiment consisted of 5 boats, 15 scientists, and about about 20 fishermen working together to tag as many fish as possible in five days, then turning around to try and resample that population to determine a ratio of tagged to untagged fish in the second sample from which an abundance could be calculated. We had near-perfect conditions on all days but one, and tagged near 72,000 fish, examining over 30,000 in the second sample, of which about 150 had tags. Preliminary estimates put the population size for the sea scallop access area (southern portion of Closed Area II) at 19 million fish.

My task now is to get the data edited and audited, and to proceed with spatial analyses that will help assess the experiment in regards to the relatively rigorous assumptions of the Petersen model. I will be presenting preliminary results and methodology at the annual American Fisheries Society conference in Ottawa, Ontario in a special symposium entitled “Tagging and it’s Use in Stock Assessments.” I will present more final results at the 7th annual International Flatfish Symposium in Sesimbra, Portugal in November. I hope to graduate in late winter.

Some photos from the field experiment can be viewed here.

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This is an article that was posted on Jul 20, 12:17 PM.

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