Updated 2017 Nightingale island rock lobster assessment

Johnston, S J; Butterworth, Doug S

Updated 2017 Nightingale island rock lobster assessment

Working Paper

2017-05

Publisher

University of Cape Town

Department

Marine Resource Assessment and Management Group

Faculty

Faculty of Science

Abstract

This paper provides a further 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 (2013-2016) high GLM standardised CPUE values (and biomass survey index values) at the island which were not initially anticipated, suggest that the negative impact of the OLIVA incident on adults may have been overestimated previously. The recent high CPUE indicates that the adult mortality in 2011 due to the OLIVA incident was much less than originally assumed. The 2017 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 catches kept constant at 75 MT or somewhat higher, though there may be a brief downturn in catch rates in the near future if the OLIVA incident led to a high mortality of juveniles at that time. An OMP is to be developed for this fishery to be used in setting the TAC for the next 2017/18 season.

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