Rapid shifts in catch composition in the artisanal Red Sea reef fisheries of Eritrea

Shifts in catch composition were registered in the Eritrean artisanal fisheries, which were launched into a renewed development after the end of the independence war in 1991. Our analysis of catch and effort data showed that total fishing effort as well as total annual catch increased more than two-fold from 1996 to 2002. Yet, overall CPUE remained unchanged upon the expansion of the fisheries, suggesting that the fisheries are still at an early stage of development. However, at lower taxonomic level, we found that the CPUE for emperors (Lethrinidae), snappers (Lutjanidae), and sharks (Elasmobranchii) decreased, while the CPUE for barracudas (Sphyraenidae), jacks (Carangidae), and tunas (Scombridae) increased. Thus, the species composition of the catches shifted toward a smaller proportion of high-value demersals (from ca. 70% in 1996 to ca. 30% in 2002), implying a change in the underlying fish community structure. Changes in CPUE could not be attributed to changes in spatial effort allocation, or to changes in gear or boats used, ruling out changes in fishing strategies as likely causes. Yet the decline in CPUE at low fishing effort does not necessarily reflect a proportional decline in fish abundance, and could possibly be caused by “hyperdepletion”. Nevertheless, the trends in CPUE are consistent with earlier findings that stocks of reef-associated demersal fishes are highly vulnerable to fishing and can decline even at the early stages of the fisheries. Therefore, the changes in CPUE could indeed represent true biomass changes, with potentially important ecological consequences. These effects could even become more severe if market conditions improve, leading to activation of latent fishing capacity, which was found to make up about 75% of the registered fleet.