Effect of the 2011 oil and soya spill events on rock lobster yields at Inaccessible and Nightingale islands

Johnston, Susan J; Butterworth, Doug S

Effect of the 2011 oil and soya spill events on rock lobster yields at Inaccessible and Nightingale islands

Working Paper

2011

Publisher

University of Cape Town

Department

Marine Resource Assessment and Management Group

Faculty

Faculty of Science

Abstract

Assessing the effects of the oil and soya spills resulting from the OLIVA incident at Nightingale on the lobster fisheries at the Tristan group of islands is difficult for a number of reasons: 1. the quantification of the impact of the oil spill on settlement and juvenile mortality is not straightforward, both at Nightingale and at Inaccessible islands to which the oil spread; 2. the soya spill, which is restricted to Nightingale island, has certainly had an impact there as evidenced by the poor catch rates experienced for recent experimental catches; however this would have been caused by either or both of a short term migration of the lobsters from the fishing area1 and an immediate additional mortality on adult lobsters; the quantification of these effects is again difficult, and importantly the consequences of the two possibilities are rather different; 3. there are two alternative models for the growth rate of lobsters at Nightingale island, and results do change appreciably depending upon which of these better approximates reality.