The Sea Turtle Bycatch Mitigation Program for the Coastal Longline Fleets and Preliminary Results of Circle Hook Experiments

Citation
IATTC WG on B (2006) The Sea Turtle Bycatch Mitigation Program for the Coastal Longline Fleets and Preliminary Results of Circle Hook Experiments. WCPFC, Busan, Republic of Korea
Abstract

This paper provides a brief description of the regional program to reduce incidental mortality of sea turtles in the eastern Pacific. The participants in the program are listed in the Appendix.

1. Description of the Problem All leatherback and most loggerhead turtle nesting populations have been declining for many years in their nesting areas of the Pacific, and incidental mortality in fisheries is believed to be one of the leading causes. The main exception are some Japanese loggerhead nesting beaches that have seen several years of increases, but other beaches in Japan, and the Australian ones, have been steadily declining.

A program was started in Ecuador in 2003, and expanded to many other Pacific coast countries in 2004 and 2005. Currently the program is (1) active in Peru, Ecuador, Colombia, Panama, Costa Rica, El Salvador and Guatemala; (2) in development en Nicaragua and in Mexico.

2. PROGRAM ACTIVITIES

2.1. Hook exchanges One of the main goals of the program is to allow the fishers to test the fishing characteristics of circle hooks, an alternative technology tested by US NOAA researchers in other regions. To achieve this goal a program to exchange the traditional J-type hooks or tuna hooks with circle hooks was started in the two major longline fisheries in the region, which target dorado (Coryphaena hippurus) and tunas, billfishes, and sharks (TBS), respectively. Most of the data obtained come from the TBS fishery. During the first year of the program, the fishers tested circle hook sizes 16/0 and 18/0, but the larger hook was not accepted by the fishers because it requires larger bait, and because of lower catch rates. So the main comparison in Peru and Ecuador became J hooks vs. 16/0 circle hooks, and the replacements became only of J hooks by C16/0 hooks in 2005. In the Central American countries, some fisheries were already using circle hooks sizes 14/0 and 15/0, but some boat owners expressed interest in testing C16/0 hooks. As we had no information on the hooking rates of turtles in this region, and a larger hook should have a lower hooking rate than a smaller one, we placed observers, and exchanged circle hooks for larger circle hooks if the fishers were willing. Not all the data have yet been included in a database, and the results here only pertain to those that have. Participants are in the process of completing the data entry process.

2.2. Distribution of de-hookers The distribution of these tools, and training in techniques to de-hook and release turtles, has continued throughout the region. Workshops are taking place regularly in all countries involved.

2.3. Observer trips and sampling effort Initially, and on the basis of the experience in Peru and Ecuador, the fisheries were separated into a dorado fishery and a fishery that targets primarily tunas, billfishes, and sharks. Based on this, the observer trips were assigned to one of those classes. However, the fisheries in Central America show different characteristics: there are mixed trips, targeting for instance tunas in some sets and dorado in others, with exactly the same gear. A total of 391 fishing trips, yielding data for 916,191 hooks, have been observed since the beginning of the program for all participating countries.