Marine & Environmental Sciences Faculty Proceedings, Presentations, Speeches, Lectures


Trophic Dynamics and Ecosystem Changes Within the SE Florida Coastal Pelagic Fish Community

Event Name/Location

62nd Annual Tuna and Billfish Conference, Lake Arrowhead, California, May 16-19, 2011

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The waters off the southeast coast of Florida are home to a unique pelagic and coastal pelagic ecosystem. The geography and physical oceanographic characteristics of this area form a condensed ecosystem where multiple apex predators are present. The big game fish, particularly scombrids such as tunas and wahoo, can be harvested within these coastal pelagic waters and are primarily targeted by recreational anglers. Presently there is a shortage of available data concerning fishes of the coastal pelagic ecosystem.

The objective of this research project is to investigate and achieve a greater understanding of coastal pelagic fishes, with an emphasis on the higher order species that inhabit the mid-range coastal pelagic to true pelagic waters, and the ecological role they play within the community ecology of the pelagic ecosystem. The selected fish species includes King Mackerel (Scomberomorus cavalla), Spanish Mackerel (S. maculates), Cero (S. regalis), Blackfin Tuna (Thunnus atlanticus), Yellowfin Tuna (T. albacares), Skipjack Tuna (Katsuwonus pelamis), Atlantic Bonito (Sarda sarda), Little Tunny (Euthynnus alletteratus), Wahoo (Acanthocybium solandri), Greater Amberjack (Seroila dumerili), and Dolphinfish (Coryphaena hippurus). These species were selected based on their position as upper trophic level predators in the marine ecosystem food web and their general habitat distribution in the coastal pelagic zone. In a one year period between March 2010 and March 2011, a total of 239 fish from the 11 species have been sampled. The samples were collected opportunistically from recreational tournament anglers in the south Florida area between West Palm Beach and the Florida Keys. From each fish specimen sampled the stomach, gonads, blood, muscle tissue, and liver tissue was collected for further analysis. Morphometric data for each specimen was also recorded.

A stable isotope analysis was performed with the muscle tissue and blood samples using carbon δ13C and nitrogen δ15N for trophic analysis. A gut content analysis was performed with the frequency of occurrence and percent composition by weight approaches used for quantitative description of the analysis. The gut content analysis is performed and compared to the stable isotope analysis to further understand the trophic interactions and trophic position among the coastal pelagic community. The preliminary results of the stomach content and stable isotope analysis from year 1 of sampling is being presented.

This research project began in 2010 and is planned to continue 2012, in an effort to collect data over 2-3 generations. The completion of this research project will achieve a greater understanding of the community ecology of these HMS coastal pelagic fishes and illustrate of the ecological roles/linkages between the coastal pelagic and pelagic ecosystems. The ecosystem and trophic data obtained from this study will also assist with the development of ecosystem based models and sustainable fisheries for the Florida East Coast HMS fishery.



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