ESR prepress abstract  -  doi: 10.3354/esr00096

ABSTRACT: Operational longline fishery characteristics, bycatch information, and loggerhead turtle satellite tracks were all used in conjunction with remotely sensed sea surface temperature data to identify the environmental area where the majority of historical loggerhead turtle bycatch occurred during 1994 to 2006. The majority of shallow longline sets and associated loggerhead turtle bycatch were in the first quarter of the calendar year above 28ºN, which corresponds to the area near the North Pacific Subtropical Frontal Zone. Based on the thermal ranges of bycatch, sets and the satellite-tagged turtles, it was recommended that the deployment of shallow sets be in waters warmer than 18.5ºC (~ 65.5ºF) isotherm to decrease loggerhead turtle bycatch. This recommendation, the basis for the TurtleWatch product, was released to fishers and managers in electronic and paper formats on December 26, 2006, to assist in decision making during the first quarter of 2007. Fishery information from 2007 was later compared with data for the years 2005 to 2006 to assess the response of the fishery to TurtleWatch. The observed fleet movement during the first quarter of 2007 was to the north of the 18.5ºC (~65.5ºF) isotherm, (in the area recommended for avoidance by the TurtleWatch product) with increased effort and lower bycatch rates. We discuss possible reasons for this decrease in turtle bycatch north of the frontal zone together with future research directions leading to possible refinement of the TurtleWatch product.