Updated 2015 Nightingale island rock lobster assessment

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 biomass surveys. The 2015 assessment updates take into account both possible additional adult and possible juvenile mortality due to the OLIVA incident in 2011. The recent (2013 and 2014) high GLM standardised CPUE values (and biomass survey index values) at the island were not anticipated, and suggest that the impact of the OLIVA may have been overestimated. A number of sensitivity trials are therefore run where alternate levels of both juvenile and adult mortality in 2011 due to the OLIVA incident are assumed. The implications of these assumptions for the future management of this resource are discussed. The recent high CPUE probably indicates that the adult mortality in 2011 due to the OLIVA incident was much less than originally assumed. However, the effect of any juvenile mortality due to the OLIVA will only become evident from CPUE trends over the next few years; such mortality could result in an appreciable drop in abundance over this period.