The ecological and socioeconomic implications of future total allowable catch decisions and illegal fishing scenarios for South Africa’s West Coast rock lobster fishery

Abstract

The West Coast rock lobster fishery, vital to South Africa, is in a critical state with only 1.1 % of its original exploitable biomass remaining. This study evaluates effects of various total allowable catch (TAC) decisions on biomass and economic performance, taking illegal fishing, currently a serious problem, into account. TAC options included two sustainable options and an option (1500 mt), which could only be feasible if illegal fishing is stopped. Biomass projections, from 2022 to 2050, are modelled from a length-based model incorporating a Beverton and Holt stock-recruit relationship. The impacts of different TAC decisions on biomass, net seasonal incomes (NSI) and net present value (NPV) are assessed. Sensitivity to different discount rates is also considered. Biomass projections suggest an imminent collapse if legal fishing limits are set too high or if IUU fishing is not substantially reduced. The NPVs for the entire sectors are found to be highest under a 1500 mt TAC but unless accompanied by a halt to IUU fishing, would result in unsustainable catch rates and rapidly declining NSI in areas where many quota holders are located. Under the 550 mt TAC scenario, there is less risk of biomass declines but the quotas for many stakeholders would be economically unviable. Lower TAC options are forecast to lead to the functional exclusion of many rights holders and reduction in employment. The most secure and economically successful strategy is considered to be adjusting annual TACs in response to the effectiveness of controlling IUU fishing and changes in biomass.