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Providing evidence to improve practice

Action: Fit one or more soft, semi-rigid, or rigid grids or frames on pots and traps Subtidal Benthic Invertebrate Conservation

Key messages

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  • One study examined the effects of fitting one or more soft, semi-rigid, or rigid grids or frames on pots and traps on subtidal benthic invertebrates. The study took place in the Corindi River system (Australia).




  • Unwanted catch abundance (1 study): One replicated, controlled study in the Corindi River system found that traps fitted with escape frames appeared to reduce the proportion of unwanted undersized mud crabs caught, compared to conventional traps without escape frames.

Supporting evidence from individual studies


A replicated, controlled study (date unspecified but appears to be 2012) in a muddy and sandy area in the Corindi River system, eastern Australia (Broadhurst et al. 2014) found that traps used to catch giant mud crabs Scylla serrata appeared to catch fewer undersized mud crabs when fitted with escape frame, compared to conventional traps without escape frames. The proportion of undersized crabs caught in traps fitted with frames appeared lower (2%) compared to conventional traps (29%; results not tested for statistical significance). In addition, the number of wounded mud crabs (undersized and commercial size) was statistically similar in traps with escape frames (0.06 crabs/trap) and conventional traps (0.13 crabs/trap). Conventional traps have four 300 × 200 mm funnel entrances but no escape frames. Conventional traps were modified by fitting two 46 × 120 mm escape frames. Seven modified traps and seven conventional traps were tested during 20 deployments. All traps were baited with sea mullet Mugil cephalus. Traps were recovered after 24 hours, and all catch identified, counted, and any wounds assessed.

Referenced papers

Please cite as:

Lemasson, A.J., Pettit, L.R., Smith, R.K., and Sutherland, W.J. (2019) Subtidal Benthic Invertebrate Conservation: Global Evidence for the Effects of Interventions. Synopses of Conservation Evidence Series. University of Cambridge, Cambridge, UK.