Short-term post-release mortality of skates (family Rajidae) discarded in a western North Atlantic commercial otter trawl fishery

Published source details Mandelman J.W., Cicia A.M., Ingram G.W., Driggers W.B., Coutre K.M. & Sulikowski J.A. (2013) Short-term post-release mortality of skates (family Rajidae) discarded in a western North Atlantic commercial otter trawl fishery. Fisheries Research, 139, 76-84.
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This study is summarised as evidence for the following.

	Action	Category
	Release protected or species of concern alive after capture Action Link

Release protected or species of concern alive after capture

A replicated study in 2009–2011 on an area of sandy and muddy seabed in the Gulf of Maine, north Atlantic Ocean, USA (Mandelman et al. 2013) reported that a large proportion of unwanted (prohibited) thorny skate Amblyraja radiata, but less than half of unwanted smooth skate Malacoraja senta, survived for three days after incidental capture in otter trawls targeting little skate Leucoraja erinacea and winter skate Leucoraja ocellata. Across all tow durations, overall survival of unwanted thorny and smooth skates after 72 h was 81% and 41% respectively. For the two commercial skates, overall survival was 92% (winter) and 86% (little). In addition, for all skates combined, species was the only significant factor affecting survival (out of other factors include catch biomass, temperature, tow duration). Individually, there were no significant predictors of 72 h mortality detected for thorny skate (data reported as statistical results; insufficient data for smooth skate). Data were collected from skates caught in 71 otter trawl deployments. Immediate mortality of skates was assessed before randomly selected live skates were transferred to deck tanks, then to sea pens that were lowered to the seafloor. Sea pens were retrieved after 72 h to assess mortality and all live skates released.

(Summarised by: Leo Clarke)