Refinement of bycatch reduction devices to exclude freshwater turtles from commercial fishing nets

Published source details Cairns N.A., Stoot L.J., Blouin-Demers G. & Cooke S.J. (2013) Refinement of bycatch reduction devices to exclude freshwater turtles from commercial fishing nets. Endangered Species Research, 22, 251-261.
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This study is summarised as evidence for the following.

	Action	Category
	Install exclusion devices on fishing gear: Tortoises, terrapins, side-necked & softshell turtles Action Link

Install exclusion devices on fishing gear: Tortoises, terrapins, side-necked & softshell turtles

A replicated, paired, controlled study in 2011–2012 in a shallow freshwater lake in Ontario, Canada (Cairns et al. 2013, same experimental location as Larocque et al. 2012) found that modifying fyke nets with a rectangular excluder device (‘bycatch reduction device’) reduced unwanted catch of turtles in a freshwater fishery. In a first-year smaller scale trial, nets modified with exclusion devices caught statistically similar numbers of turtles (3–4 turtles) compared to unmodified nets (11). The catch of target and non-target fish was also statistically similar between modified (109–144 individuals) and unmodified nets (224). However, in the second year larger scale trial, unwanted catch of turtles was lower in modified nets (0.03 turtles/trapping effort) compared to unmodified nets (0.13). Target species catch was also lower in modified nets (0.64 individuals/trapping effort) compared to unmodified nets (0.95). In September 2011, two fyke nets connected by an entrance net (7 hoops/net, 0.91 m diameter) were deployed in a shallow lake (2.8 m average depth, 780 ha total area) in threes: unmodified net, modified with a 22.5 x 5 cm copper rectangle, or modified with 5 cm spaced vertically-oriented bars across the mouth of the net (nine groups of nets in one site). In April–June 2012, the set up was repeated twice at 11 sites, but did not include nets with the barred exclusion device. All target and non-target catch was identified, counted and released.

(Summarised by: Maggie Watson, Katie Sainsbury)