Prevalence of Ingested Fish Hooks in Freshwater Turtles from Five Rivers in the Southeastern United States

David A Steen,Brittney C Hopkins,James U Van Dyke,William A Hopkins,Bazartseren Boldgiv

doi:10.1371/journal.pone.0091368

Abstract

Freshwater turtles may ingest baited fish hooks because many are opportunistic scavengers. Although the ingestion of fish hooks is known to be a source of mortality in multiple vertebrate groups, the prevalence of hook ingestion by freshwater turtles has not been well studied. We trapped turtles from five rivers in the southeastern United States and used radiographs to examine over 600 individuals of four species. Depending on the species, sex, and age class, 0–33% of turtles contained ingested fish hooks. For some species, larger turtles were more likely to contain a fish hook than smaller individuals. Freshwater turtle demography suggests that even small increases in adult mortality may lead to population declines. If our study areas are representative of other aquatic systems that receive fishing pressure, this work likely identifies a potential conflict between a widespread, common recreational activity (i.e., fishing) and an imperiled taxonomic group.

Highlights

Recreational fishing is a widespread activity [1], [2], that poses threats to aquatic wildlife assemblages through the production of bycatch [3]
We add to the body of knowledge regarding freshwater turtle conservation by reporting the proportions of freshwater turtles captured at our study sites that contained ingested fish hooks
Given the injuries associated with hook ingestion in other taxa (e.g., [16,17,18]), our data suggest that recreational fishing is a potential anthropogenic threat for this imperiled group

Summary

Introduction

Recreational fishing is a widespread activity [1], [2], that poses threats to aquatic wildlife assemblages through the production of bycatch [3]. Because freshwater turtles are opportunistic scavengers and take live prey, they are likely vulnerable to capture with baited hooks set to catch fish [10]; they are targeted by commercial and recreational collectors via this same method [11]. Fish hooks were found in three of 17 (,18%) X-rayed female European pond turtles, Emys orbicularis Linnaeus 1758, from a heavily-fished series of ponds in France [15], suggesting significant proportions of turtles may be affected

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Results

Conclusion