The finfish catch efficiency of alternative gear designs that reduce sea turtle bycatch in bottom trawl fisheries

Christopher Parkins, University of Rhode Island

Abstract

The summer flounder bottom trawl fishery has shown increased interactions with sea turtles as populations increase due to continued protection under the endangered species act. In this study, two separate gear designs that potentially can reduce sea turtle bycatch in the summer flounder bottom trawl fishery were tested for finfish catch efficiency. The first manuscript examines two experiments involving two separate turtle excluder device (TED) designs. The second manuscript examines a topless trawl as a possible replacement for fixed grid TEDs as sea turtle bycatch reduction devices. ^ In the first manuscript, experiment #1 evaluated the catch efficiency of a certified National Marine Fisheries Service (NMFS) standard turtle excluder device (TED) to the standard trawl in response to the concern from commercial fishermen that their target catch, summer flounder was being lost due to the inefficient design of the TED. Experiment #2 was performed to test an alternative TED design to the previous tested NMFS certified TED. In experiment #1 the NMFS certified TED(experimental) was compared to a standard trawl (control) using a paired tow design on one vessel using consecutive tows, alternating between the control and the experimental trawl in the following sequence: ABBA (A=experimental trawl, B=control trawl) to minimize gear handling time. A paired t-test was used to test for differences between the combined mean weight (catch by species) per tow in kilograms of the standard trawl and NMFS certified TED. The NMFS certified TED evaluated in this project had a significant reduction in summer flounder catch as compared to the standard trawl (35% loss). These findings indicated a need for NMFS to develop a more efficient alternative to the currently used NMFS certified TED. ^ Experiment #2 evaluated the catch efficiency of the northeast modified TED to the NMFS certified TED used in experiment #1. The evaluation used a paired tow design on two vessels using consecutive tows, alternating between the control (NMFS certified TED) and the experimental (northeast modified TED) trawl in the following sequence: ABBA (A=NMFS certified TED, B=northeast modified TED) to minimize gear handling time. A paired t-test was used to test for differences between the combined mean weight (catch by species) per tow in kilograms of the NMFS certified TED and northeast modified TED. The northeast modified TED evaluated in this project did not have a significant difference in summer flounder catch as compared to the NMFS certified TED. ^ The findings of this research indicate that there is a significant reduction in the summer flounder catch with both the NMFS certified TED and a northeast modified TED. These results indicate that NMFS should not move forward with regulations to implement the TED in the summer flounder fishery until a more efficient design for excluding turtles can be developed. ^ The evaluation of the catch efficiency of a topless trawl is described in the second manuscript. The study was conducted in response to a need for an alternative to turtle excluder devices (TEDs) which have a documented loss of summer flounder, the target species catch, ranging from 35 to 28%. ^ The topless trawl (experimental) was compared to a standard trawl (control) using a paired tow design on one vessel using consecutive tows, alternating between the control and the experimental trawl in the following sequence: ABBA (A=experimental topless trawl, B=control trawl) to minimize gear handling time. A paired t-test was used to test for differences between the combined mean weight (catch by species) per tow in kilograms of the standard and topless trawl. The topless trawl net evaluated in this project had no significant difference in summer flounder catch as compared to the standard 2-seam flounder trawl. ^ The findings of this research indicate that there is no difference between the catch rate of summer flounder when using a topless trawl in place of the standard summer flounder trawl net. These results indicate that NMFS should move forward with designing a study to determine the ability of a topless trawl to exclude wild sea turtles.^

Subject Area

Agriculture, Fisheries and Aquaculture

Recommended Citation

Christopher Parkins, "The finfish catch efficiency of alternative gear designs that reduce sea turtle bycatch in bottom trawl fisheries" (2011). Dissertations and Master's Theses (Campus Access). Paper AAI1505774.
http://digitalcommons.uri.edu/dissertations/AAI1505774

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