Incidental capture and mortality of sea turtles in the industrial double-rig-bottom trawl fishery in south-eastern Brazil
Abstract
© 2019 John Wiley & Sons, Ltd. Incidental capture by fisheries is one of the principal
threats to sea turtles. This study analysed spatial and temporal patterns of sea turtle
bycatch, and estimated the direct initial mortality rate of these animals, in the
industrial double-rig-bottom trawl fishery in south-eastern Brazil. This is also the
first attempt to relate bycatch/at-sea mortality in bottom trawling to stranded turtles
found along the adjacent coast. The fishery was monitored from October 2015 to April
2018 through data collected voluntarily by the captains of eight industrial double-rig
trawlers. Two hundred and one sea turtles were captured during 9362 tows (43,657.52
trawling hours), resulting in a catch per unit effort (CPUE) of 0.0025 ± 0.0032 turtles
h−1 with a standard net of 30.5 m headrope, with no significant difference between
the estimated CPUEs for licensed shrimp and demersal fish trawlers. Caretta caretta
(52.24%) and Lepidochelys olivacea (38.81%) were the most frequently captured species.
According to Generalized Linear Models, C. caretta bycatch was significantly higher
during winter, at lower latitudes (−24° to −23°) and higher longitudes (−42° to −40°),
while the L. olivacea bycatch was significantly higher at higher latitudes (−23° to
−21°). The direct initial mortality rate of sea turtles in the shrimp trawlers was
7.65 ± 3.85%. However, none of the dead individuals subsequently released with plastic
tags (n = 10) were found stranded on the coast. Mortality was not significantly related
to the depth or duration of the trawling. The results of this study suggest the need
for improvements to the current management of the bottom trawl fishery in Brazil,
moving from a species-based to a spatial and seasonal-based approach. There is also
a need to develop turtle excluder devices adapted to local fishing conditions.
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https://hdl.handle.net/10161/19901Published Version (Please cite this version)
10.1002/aqc.3252Publication Info
Tagliolatto, AB; Giffoni, B; Guimarães, S; Godfrey, MH; & Monteiro-Neto, C (2019). Incidental capture and mortality of sea turtles in the industrial double-rig-bottom
trawl fishery in south-eastern Brazil. Aquatic Conservation: Marine and Freshwater Ecosystems. 10.1002/aqc.3252. Retrieved from https://hdl.handle.net/10161/19901.This is constructed from limited available data and may be imprecise. To cite this
article, please review & use the official citation provided by the journal.
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Matthew H. Godfrey
Adjunct Associate Professor

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