A spatio-temporal assessment of the Trachinotus botla shore-fishery in KwaZulu-Natal, South Africa

Abstract

The shore-fishery for Trachinotus botla in KwaZulu-Natal appears to be in a stable state. A per-recruit assessment showed that the species is currently underexploited (spawner biomass-per-recruit = 75% of pristine levels) and that fishing mortality could theoretically be increased. The fishery was shown to display considerable spatial and temporal variability with resource abundance increasing north-easterly towards Mozambique with catch per unit effort (CPUE) peaking during summer. Trachinotus botla displayed random movement patterns indicative of a surf-zone resident, with 78% of the recaptures being made within 1 km of the tagging site. The movement pattern observed was not affected by fish size or time at liberty. An increasing trend in mean annual CPUE since 2002 suggests that either the resource is increasing since the promulgation of the ban on beach driving or possibly as a result of increased targeting of this species using a relatively modern technique known locally as ‘dropshot’ fishing. It is likely that the beach driving ban has shifted fishing effort to accessible nodes along the coast where there is some evidence of localised overexploitation.