MEPS 323:253-261 (2006)  -  doi:10.3354/meps323253

Diving behavior and delayed mortality of olive ridley sea turtles Lepidochelys olivacea after their release from longline fishing gear

Yonat Swimmer1,*, Randall Arauz2, Marti McCracken1, Lianne McNaughton3, Jorge Ballestero2, Mike Musyl3, Keith Bigelow1, Richard Brill4

1National Marine Fisheries Service, Pacific Island Fisheries Science Center, 2570 Dole Street, Honolulu, Hawaii 96822
2PRETOMA, 120–1100 Tibás, San José, Costa Rica
3Joint Institute for Marine and Atmospheric Research, University of Hawaii, 1000 Pope Road, Honolulu, Hawaii 96822, USA
4Virginia Institute of Marine Science and National Marine Fisheries Service, 1208 Greate Road, Gloucester Point, Virginia 23062, USA

ABSTRACT: We deployed pop-off satellite archival tags (PSATs) on 14 olive ridley turtles Lepidochelys olivacea and 1 green turtle Chelonia mydas in the eastern tropical Pacific Ocean between November 2001 and June 2003 to determine dive behavior and post-release mortality following interactions with longline fishing gear. Nine olive ridleys and 1 green turtle were captured by longline fishing gear, and 5 free swimming olive ridleys were hand-captured at the surface to serve as controls. Hooks were removed from all longline-caught turtles, with the exception of 1 olive ridley turtle. PSATs remained on control- and longline-caught olive ridleys for an average of 61 and 54 d, respectively (range: 26 to 115) and on the green turtle for 26 d. Olive ridleys spent nearly all of their recorded time within the top 60 m, with very few dives exceeding 100 m. Over 95% of the time was spent between water temperatures of 22 and 28°C and turtles’ dive behaviors appeared to be correlated with oceanographic variables (e.g. sea surface temperature and chlorophyll concentration). There were no clear differences evident either in horizontal movements, depth distributions, or associations with specific water temperatures between longline-caught and control turtles. Our data showed only one mortality event, that of a control turtle that died and sank 66 d after being tagged. We conclude that olive ridley turtles that are lightly hooked and handled properly survive and generally behave normally following interactions with shallow-set longline gear.


KEY WORDS: Marine turtles · Pop-off satellite archival tags · PSATs · Eastern tropical Pacific Ocean


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