Updated 2016 Nightingale island rock lobster assessment

Johnston, Susan; Butterworth, Doug S

Updated 2016 Nightingale island rock lobster assessment

Working Paper

2016-06

Publisher

University of Cape Town

Department

Marine Resource Assessment and Management Group

Faculty

Faculty of Science

Abstract

This paper provides an updated assessment of the rock lobster resource at Nightingale island. This assessment includes updated data from both the commercial fishery and the biomass surveys. The recent (2013-2015) high GLM standardised CPUE values (and biomass survey index values) at the island were not initially anticipated, and suggest that the impact of the OLIVA on adults may have been overestimated. The recent high CPUE indicates that the adult mortality in 2011 due to the OLIVA incident was much less than originally assumed. The 2016 RC assessment thus now assumes zero adult mortality in 2011 due to the OLIVA incident, but continues to assume an 80% juvenile mortality due to this incident in 2011. Projections suggest that the resource could readily sustain future constant catches at 75 MT, though there may be a brief downturn in catch rates shortly if the OLIVA incident led to a high mortality of juveniles at that time.

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