Abstracts Category : Other

Fisheries in a changing environment : the impacts of the reduction in Shatt Al Arab flow on nearshore fish stocks in the Northern Persian Gulf

by Hasan Abdulrahman Ben

When fish catches decline, the standard recommended management solution is to reduce fishing mortality to allow stock recovery to more productive levels. This recommendation is based on the assumption that the most likely cause of the decline in the first place is fishing. Natural regime shifts and human-induced environmental changes are, however, often equally important factors in driving catch declines. In the Northern Persian Gulf, many commercial fish stocks are declining, raising questions about two main causes: overfishing and reduction in the flow of the major river, Shatt Al Arab. In Kuwait, the latter cause is strongly suspected of driving catch declines, especially with the implementation of high length limits and apparently good protection of juvenile nursery areas. Here I assess three case studies of Kuwait fish stocks and investigate the impact of reduced Shatt Al Arab flow on fish recruitment patterns. We found neutral and negative apparent capacity change in the green tiger shrimp stock and the orange-spotted grouper stock, respectively. These results suggest declining productivity in the nursery area of the orange-spotted grouper, but not in that of the tiger shrimp stock. In the case of the yellow-fin seabream assessment, the estimation of the relative recruitment was unreliable, hence the inability to examine the relationship between recruitment and the reduction in the flow rate of Shatt Al Arab. Our results demonstrate that reductions in Shatt Al Arab river flow are likely to impact fish recruitment patterns, causing changes in fish stock sizes. The findings presented here are expected to be a starting point for a more detailed investigation that tries to bring together data on what has been changing over time in the nearshore nursery environments, since most of the commercial fish stocks are inshore/estuarine dependent. Such investigation would be very critical for the fisheries management in deciding, for example, whether a reduction of fishing effort would be beneficial.