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, 2 (10), e1041

Small-scale Fisheries Bycatch Jeopardizes Endangered Pacific Loggerhead Turtles

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Small-scale Fisheries Bycatch Jeopardizes Endangered Pacific Loggerhead Turtles

S Hoyt Peckham et al. PLoS One.

Abstract

Background: Although bycatch of industrial-scale fisheries can cause declines in migratory megafauna including seabirds, marine mammals, and sea turtles, the impacts of small-scale fisheries have been largely overlooked. Small-scale fisheries occur in coastal waters worldwide, employing over 99% of the world's 51 million fishers. New telemetry data reveal that migratory megafauna frequent coastal habitats well within the range of small-scale fisheries, potentially producing high bycatch. These fisheries occur primarily in developing nations, and their documentation and management are limited or non-existent, precluding evaluation of their impacts on non-target megafauna.

Principal findings/methodology: 30 North Pacific loggerhead turtles that we satellite-tracked from 1996-2005 ranged oceanwide, but juveniles spent 70% of their time at a high use area coincident with small-scale fisheries in Baja California Sur, Mexico (BCS). We assessed loggerhead bycatch mortality in this area by partnering with local fishers to 1) observe two small-scale fleets that operated closest to the high use area and 2) through shoreline surveys for discarded carcasses. Minimum annual bycatch mortality in just these two fleets at the high use area exceeded 1000 loggerheads year(-1), rivaling that of oceanwide industrial-scale fisheries, and threatening the persistence of this critically endangered population. As a result of fisher participation in this study and a bycatch awareness campaign, a consortium of local fishers and other citizens are working to eliminate their bycatch and to establish a national loggerhead refuge.

Conclusions/significance: Because of the overlap of ubiquitous small-scale fisheries with newly documented high-use areas in coastal waters worldwide, our case study suggests that small-scale fisheries may be among the greatest current threats to non-target megafauna. Future research is urgently needed to quantify small-scale fisheries bycatch worldwide. Localizing coastal high use areas and mitigating bycatch in partnership with small-scale fishers may provide a crucial solution toward ensuring the persistence of vulnerable megafauna.

Conflict of interest statement

Competing Interests: The authors have declared that no competing interests exist.

Figures

Figure 1
Figure 1. Kernel Density of Loggerhead Turtle Habitat Use in the North Pacific.
Inset: Positions of tracked loggerheads (yellow) spanned the North Pacific Basin. The 50% utilization distribution for observed loggerheads consisted of an area of 4,115 km2 centered ∼32 km from the BCS coast, well within the 55 km range of small-scale fisheries (white line).
Figure 2
Figure 2. Loggerhead Carcasses Stranded at Playa San Lázaro 2003–5.
985 loggerhead carcasses stranded along the 43 km Playa San Lázaro from 2003–5. Nearly 80% (N = 781) of carcasses stranded from May-September, corresponding to seasonal operation of local small-scale fisheries (red line). Bars represent SD within months.

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