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theses

The goal of this study was to better understand where adult winter flounder (Pseudopleuronectes americanus) are, both in distribution and while seasonally spawning in the central to southern Mid-Atlantic Bight, through the use of historic datasets and tagging and tracking methods. I accomplished this with the use of three historic bottom trawl surveys to investigate if there was a shift in the distribution of winter flounder at the southern extend of the their range. In addition, the relationship between ocean temperatures and winter flounder centers of biomass and abundance was tested to see if temperature was a driver. To characterize seasonal migration, adult winter flounder (n=231) were tagged with three tag types. I targeted adult fish, using fish length and the gonadosomatic index as an indicator. To reconstructing an individual’s location using the environmental data recorded from a data logging archival tag, three state space models were developed and tested for model accuracy. I subsampled the trawl data and used data below the Hudson Valley and found that the distribution of winter flounder has shifted over the last few decades. A distributional shift north along the continental shelf was the most common trend across surveys, but there were several other changes in the distribution (e.g., across shelf location and depth) that were season and survey specific. These spatial shifts, along with abundance, were not temporally similar to an increase in ocean temperatures. While the tagging efforts were successful, I had a low recapture rate. Most of the tagged fish were female and mature. I observed two movement behaviors in the fall of 2012, including two individuals that moved inshore and north from the release site and two offshore. The recovery of one archival tag helped inform the three state space models developed. I used two data matching and simulation state space models and one particle filter model to reconstruct fish location. All of the models were tested on simulated known fish paths, and while they performed similarly on short time scales, at larger time scales the particle filter outperformed the data matching and simulation state space models.

ETD_6396

M.S.

Includes bibliographical references

by Kaycee E. Coleman

doi:10.7282/T35T3NBD

ETD graduate

The author owns the copyright to this work.