Assessing changes in the distribution and range size of demersal fish populations in the Benguela Current Large Marine Ecosystem

Distributional change, expressed as range expansion or contraction , has been observed in many marine populations and related to changes in the environment. The extent of such distributional changes is also expected to increase in response to future climate change. The Benguela Current Large Marine Ecosystem (BCLME) which adjoins the south-western coast of Africa is a global marine hotspot with long-term warming occurring over a large area. The area is also an important centre of marine food production for three countries-South Africa, Namibia and Angola and is considered to be vulnerable to future climate change or increased climate variability. In this study we analysed change in distribution and range size of several demersal fish species in the BCLME over the period 1985-2010, including both commercial and non-commercial fish populations. Some of the observed changes in distribution and range size correspond to what is expected with increased warming whereas others appear to the contrary. Overall the results of the study highlight the complex nature of the response of fish population to climate change.