Theses and Dissertations

Title: Short-term Survival and Movements of Small Carcharhind Sharks After Catch-And-Release Angling in the Northeast Gulf of Mexico

Name: Gurshin, Chirstopher William Damon

Degree: MS

Chair: Stephen T. Szedlmayer


University: Auburn University

Location: Auburn, Alabama

Date: 2000

Pages: 85

Keywords: shark,catch and release,bycatch


Ultrasonic telemetry was used to assess postrelease survival and movements of small hooked sharks (Carcharhinidae) in a coastal nursery area in the northeast Gulf of Mexico. Sharks were caught with standardized hook-and-line gear during June-October 1999. Ten Atlantic sharpnose Rhizoprionodon terraenovae, three finetooth Carcharhinus isodon, two spinner C. brevipinna, and two blacktip sharks C. limbatus were continuously tracked for a mean duration of 2.5 ±1.8 SD h (0.5-5.9 h). Activity and movement suggested short-term survival was at least 94%. The mean total rate of movement for all sharks was 1.7 ± 2.0 SD km/h and the range was 0.1-16.4 km/h. The mean total rate of movement of C. limbatus (3.4 km/h) was significantly higher compared to the other species (P < 0.05). Movement patterns did not differ between jaw-hooked sharks and sharks hooked in vital organs. Total swimming distance was positively correlated with mean salinity at capture (r = 0.66, P < 0.05). Rate of area covered increased as mean disolved oxygen at capture increased (R2 = 0.84, P < 0.05). A constant rate of movement suggested minimal postrelease trauma. The mean direction of net movement was 200° ± 88 SD or south southwest towards deeper water. The present study suggest high (at least 94%) survival of small coastal sharks after catch-and-release. Thus, to reduce bycatch mortality of small coastal sharks or sharks caught in nursery areas as young of the year, fishers should be encouraged to practice catch and-release.

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