Date of Award

2024

Document Type

Thesis

Degree Name

Bachelors

Department

Natural Sciences

First Advisor

Rycyk, Athena

Area of Concentration

Marine Biology

Abstract

Recreational and commercial fisheries are responsible for a large quantity of elasmobranch (sharks, skates, and rays) deaths annually. A significant portion of this mortality is the result of bycatch, the unintentional capture of unwanted species while targeting a different species. Specifically, in hook and line fisheries, sharks are often caught as bycatch when they are subjected to baited lines or lines that have already caught a fish (e.g. a sport fish that is actively fighting on the line). As apex predators, these hunters are driven by food reward and cannot discern the difference between a sport fish caught on a fishing line and an easy meal. Previous research has suggested that magnets might be a feasible elasmobranch deterrent due to a sensory organ specific only to elasmobranchs called the ampullae of Lorenzini. This physical characteristic allows elasmobranchs to detect minute differences in electromagnetic field for the purpose of sensing the muscle contractions of their prey. The purpose of this study is to construct a prototype magnetic deterrent with an original case design and test the device in Sarasota Bay and the surrounding Gulf of Mexico under recreational fishing conditions (rod and reel). Two types of data collection were carried out including boat-based and shore-based data collection. For both categories, the presence of the magnet prototype was compared to deployments without the magnet, and the proportional difference in elasmobranch capture between the control group (no magnet) and the test group (magnet deterrent) was analyzed. A slight relationship was observed between the two groups, with the proportion of elasmobranchs caught in the control group being 6.7% higher than the proportion of elasmobranchs caught in the test group. However, the sample size for this experiment was very small (total sample size of 21; control group sample size of 15; test group sample size of 6) and therefore it is not possible to generalize the results and form conclusions about the population.

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