Post-Release Mortality

Sustainable fisheries management requires that bycatch mortality due to fishing activities be accurately estimated and considered in population status assessments and management measures [1]. In many instances, particularly with sharks which can ‘bite-off’ longlines and for which there are Conservation Measures requiring ‘no retention’ for several species, quantifying bycatch post-release mortality (PRM), and thus total bycatch mortality, is difficult. References in this category address different aspects of bycatch PRM. For example, SPC and WCPFC (2017) report on a workshop to provide scientifically robust and practical protocols for shark PRM tagging studies. Coelho et al [2011] evaluate elasmobranch at-haulback mortality by species, size and sex, which feeds into risk analysis estimates of shark survival after being captured and discarded by longline commercial fisheries. Other studies aim to identify operational, environmental, and biological variables contributing to PRM and make suggestions on how to reduce it [e.g. 3,4].

Post-release mortality is synonymous with post-release survival.


  1. SPC, WCPFC (2017) Report of the Expert Workshop on Shark Post-Release Mortality Tagging Studies: Review of Best Practice and Survey Design. Wellington, New Zealand
  2. Coelho R, Lino PG, Santos MN (2011) At-haulback mortality of elasmobranchs caught on the Portuguese longline swordfish fishery in the Indian Ocean. IOTC–2011–WPEB07–31
  3. Dapp DR, Huveneers C, Walker TI, et al (2016) Moving from Measuring to Predicting Bycatch Mortality: Predicting the Capture Condition of a Longline-Caught Pelagic Shark. Front Mar Sci 2:126. doi: 10.3389/fmars.2015.00126
  4. Williard A, Parga M, Sagarminaga R, Swimmer Y (2015) Physiological ramifications for loggerhead turtles captured in pelagic longlines. Biology Letters 11:20150607. doi: 10.1098/rsbl.2015.0607