Reducing the mortality of freshwater turtles in commercial fish traps

Published source details Lowry M.B., Pease B.C., Graham K. & Walford T.R. (2005) Reducing the mortality of freshwater turtles in commercial fish traps. Aquatic Conservation: Marine and Freshwater Ecosystems, 15, 7-21.
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This study is summarised as evidence for the following.

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

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

A replicated, controlled study (years not provided) in a pool, lake and creek in New South Wales, Australia (Lowry et al. 2005) found that adding an escape ring to a carp Cyprinus carpio trap allowed most short-necked turtles Emydura macquarii to escape. In escape trials, 85 of 120 turtles (71%) escaped within 90 minutes and 92 of 120 turtles (77%) escaped within four hours. Smaller turtles (average straight carapace width 17 cm) were more likely to escape than larger turtles (average width 19 cm). The average time for escapes was 63 minutes for centre-placed exits and 92 minutes for end placed exits. Very few carp escaped through the turtle exit during escape trials (14 of 120, 12% of fish escaped) and the authors reported that numbers of carp caught/day indicated that few carp were escaping through the turtle exit in fishing trials (see original paper). Cylindrical (90 cm diameter x 170 cm long) mesh carp traps were used modified with a 23 cm escape ring on the upper trap surface, either in the centre or at the opposite end to the entrance (which was closed for the experiment). A mesh platform was placed under the escape ring to aide turtles exiting. Ten individually-marked turtles were randomly selected to take part in six trials of each trap type. Turtles were placed as a group in the trap, submerged for 4 h and escapes recorded. The traps were also tested for carp escapes in a lake (escape trials) and creek (fishing trials).

(Summarised by: Maggie Watson, Katie Sainsbury)
Install exclusion devices on fishing gear: Tortoises, terrapins, side-necked & softshell turtles

A replicated, controlled study (years not provided) in two upper tidal creeks in New South Wales, Australia (Lowry et al. 2005) found that using 100 mm exclusion rings on eel Anguilla spp. traps reduced unwanted catch of short-necked turtles Emydura macquarii. Fewer turtles were caught in traps modified with exclusion rings (8 individuals) compared to unmodified traps (54). Most turtles caught in modified traps were smaller than those caught in unmodified traps (see paper for details). Commercially-targeted eel catch (numbers and size of eels) was similar between modified (49 individuals caught overnight, 21,005 g total catch weight) and unmodified traps (25 individuals, 8,535 g). Standard commercial eel traps (50 cm wide x 40 cm high x 90 cm long mesh traps) had 100 mm PVC rings placed in the entrance funnel. In one site three traps with exclusion rings and three unmodified traps were fished overnight and in a second site, four traps with rings and four unmodified traps were fished for 5 h during the day, cleared, and then fished overnight (12 h). Traps were baited with frozen pilchards Sardinops neopilchardus.

(Summarised by: Maggie Watson, Katie Sainsbury)