Freshwater turtle by-catch from angling in New Brunswick, Canada

Abstract

Turtles are among the most threatened vertebrate taxa, with populations especially vulnerable to any increase in adult mortality. By-catch from freshwater angling, as a potential cause of turtle mortality is poorly documented and little understood. Here we document cases of turtle by-catch by recreational anglers in an urban park in New Brunswick and among the wider angling communities in the province. We also consider factors that may influence rates of hooking. Although we are unable to estimate turtle hooking frequency for the provincial recreational angling community as a whole, five of 75 (~7%) anglers interviewed in the urban park reported interactions with a turtle, with most reported incidents (75%) involving hooking. Snapping Turtles (Chelydra serpentina) seem to be more prone to hooking than Eastern Painted Turtles (Chrysemys picta picta). Although we conclude that turtle hooking by recreational anglers appears to be generally uncommon in New Brunswick, even apparently low by-catch rates may be sufficient to lead to population declines at heavily fished sites. The collection of additional data on turtle by-catch in the recreational fishery in Canada is warranted.

Anthropogenic Threats to Alligator Snapping Turtles (Chelydridae: Macrochelys)

“…Commercial fishing bycatch (threat 5.4.4: unintentional effects of large-scale fishing; IUCN 2012a) has been extensively studied in sea turtles, with entrapment or entanglement gear and hook ingestion (with or without attached lengths of line) considered to be primary fatal threats (Di Bello et al 2013, Lewison et al 2014, National Research Council 1990, Parga 2012, Schuyler et al 2014. Similar rates of freshwater turtle mortality result from various other types of commercial and recreational fishing gear (Barko et al 2004;Browne et al 2020;Larocque et al 2012aLarocque et al , 2012cNemoz et al 2004;Steen et al 2014). Surprisingly, as part of Florida's Fisheries-Independent Monitoring program in 2005-2019, biologists incidentally captured M. temminckii in and around Apalachicola Bay using 6.1-m otter trawls (n = 15), 21.3-m seine nets (n = 2), and 183-m seine nets (n = 1) (Meagan Schrandt, Fish and Wildlife Research Institute, St. Petersburg, FL, pers.…”

Fishhook ingestion by the Red-eared Slider, Trachemys scripta elegans (Wied 1839), in the Pecos River, New Mexico, USA

“…Freshwater turtles are amongst the most threatened vertebrate taxa (Lovich et al 2018) and are particularly vulnerable to declines given their long-lived and slow-maturing nature (Browne et al 2020). Fishhook ingestion by turtles could potentially be a source of additive mortality and may contribute to population declines (Hyland 2002;Steen and Robinson 2017).…”

“…Fishhook ingestion by turtles has been documented for both freshwater and marine species (Valente et al 2007;Steen et al 2014;Swimmer et al 2014;Steen and Robinson 2017;Browne et al 2020;Vecchioni et al 2020). However, there is little information available about the extent to which accidental bycatch impacts turtle populations and survival rates (Browne et al 2020), or how such injuries could affect the reproductive success of adult females.…”

“…Fishhook ingestion by turtles has been documented for both freshwater and marine species (Valente et al 2007;Steen et al 2014;Swimmer et al 2014;Steen and Robinson 2017;Browne et al 2020;Vecchioni et al 2020). However, there is little information available about the extent to which accidental bycatch impacts turtle populations and survival rates (Browne et al 2020), or how such injuries could affect the reproductive success of adult females. Steen and Robinson (2017) indicate that recreational fishing can result in negative pressures on freshwater turtle populations in the USA, with species-and population-specific mortality rates of turtles ranging from 1-11%.…”

“…In areas where recreational fishing is common, bycatch and fishhook ingestion may be a source of additive mortality, cumulatively contributing to deaths (both anthropogenic and natural [e.g., consumption by native predators, extreme weather conditions, bacterial infection, age, etc. ; Brooks et al 1990]) and subsequently leading to population declines (Hyland 2002;Steen and Robinson 2017;Browne et al 2020). When ingested, fishhooks can perforate portions of the gastrointestinal tract of turtles, resulting in various consequences including cellulitis, peritonitis, stricture formations, and tearing (Hyland 2002;Valente et al 2007;Di Bello et al 2013).…”