Brendan Talwar

A crowdfunded ecology project byBrendan Talwar

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Post-Release Mortality of Deep-Sea Isopods!

Lab Note #23
Jun 18, 2016

Hi everyone,

We're excited to share the first published manuscript from our work focused on the post-release mortality of deep-sea bycatch species! Here is the abstract and a link to the article itself. 

Abstract:

Estimates of post-release mortality (PRM) rates for discarded bycatch are largely unknown across marine fisheries and represent a substantial source of uncertainty when estimating total fishery mortality. One way to predict PRM is through the use of reflex action mortality predictors (RAMP), whereby the presence or absence of target reflexes and known post-release fate are used to create a delayed mortality model. We employed reflex impairment assessments in concert with post-capture caging and video monitoring to predict 5-d PRM rates for the deep-sea giant isopod Bathynomus giganteus, a common bycatch species in numerous deepwater fisheries worldwide, and also considered the factors contributing to mortality. Mortality rates 5 d post-capture ranged from 50 to 100% and both RAMP scores and time at the surface were significant predictors of mortality, although our conclusions regarding the effect of surface time are limited. In-cage video documented little movement within the 24-h monitoring period following capture, and it appeared that surviving individuals often fed within the holding period after cage deployment. Our results suggest that PRM in B. giganteus is common and that this unaccounted source of mortality should be quantified for other deep-sea crustaceans captured as bycatch.

Full PDF Article

Full HTML Article

Thanks for making this research possible! And, as always, thank you to all the folks at the Cape Eleuthera Institute who conducted the field work with me!

Best,

Brendan


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