Comparing the effects of offset and non-offset circle hooks on catch rates of fish and sea turtles in a shallow longline fishery

Publication Type:Journal Article
Year of Publication:2010
Authors:Y. Swimmer, Arauz, R., Wang, J., Suter, J., Musyl, M., Bolanos, A., Lopez, A.
Journal:Aquatic Conservation-Marine and Freshwater Ecosystems
Volume:20
Pagination:445-451
Date Published:Jun
Type of Article:Article
ISBN Number:1052-7613
Accession Number:ISI:000279822100010
Keywords:bait, behavior, by-catch, bycatch, bycatch mitigation, circle hook offsets, LEPIDOCHELYS-OLIVACEA, LOGGERHEAD, longline fishing, marine, mortality, PELAGIC LONGLINES, REDUCE, RELEASE, sea turtle fisheries, sea turtles
Abstract:

1. This study compared the catch rates of targeted dolphin fish or mahimahi (Coryphaena hippurus), and sea turtles and other fish bycatch in a shallow-set Costa Rican longline fishery using 14/0 circle hooks with and without a 101 offset. The effect of hook offset on hooking location and injury in captured sea turtles, specifically if the hooking was external, in the mouth, or in the esophagus was also evaluated. 2. Results were compared from six trips totalling 33 876 hooks with squid (Dosidicus gigas) used as bait. In total, mahimahi catch-per-unit-effort (CPUE, expressed as number caught per 1000 hooks) was similar between hook types (CPUE similar to 52). 3. Olive ridley sea turtles (Lepidochelys olivacea) were caught on all 42 sets. In total, 640 olive ridley turtles were caught and released alive. There were no significant differences in the number of sea turtles caught between hooks with and without an offset (CPUE similar to 19) nor between hook type and anatomical hooking location, suggesting similar levels of injury for turtles caught on each hook type. 4. These data suggest that a 101 offset on 14/0 circle hooks does not confer any selective advantages over hooks with no offset with respect to capture rates of mahimahi, sea turtles, sharks, or pelagic stingrays in a shallow set pelagic longline fishery. Copyright (C) 2010 John Wiley & Sons, Ltd.

Short Title:Aquat. Conserv.-Mar. Freshw. Ecosyst.Aquat. Conserv.-Mar. Freshw. Ecosyst.
Alternate Journal:Aquat. Conserv.-Mar. Freshw. Ecosyst.
Scratchpads developed and conceived by (alphabetical): Ed Baker, Katherine Bouton Alice Heaton Dimitris Koureas, Laurence Livermore, Dave Roberts, Simon Rycroft, Ben Scott, Vince Smith