Benefits of stock enhancement: The case of the Iranian kutum fishery

Harvesting of the fish resources as an economic activity, which is strictly tied to biological matters, needs to be modeled proficiently through bioeconomic analysis. In this study, a bioeconomic age-structured model is used to analyse the profitability of Kutum fishing in Iranian coastal waters of the Caspian Sea. Dwindling population of this species has been revived through an enhancement programme, since 1982 in southern Caspian areas by Iranian Fisheries Organization (IFO). Biological age-structured models in this paper were used to estimate the catch amount under two different hypotheses of Beverton-Holt and Ricker about stock-recruitment relationship. Considering the effects of the enhancement programme on recruitment and catch and also on the fishing activity costs, the net present value of the profits from fishing activity is calculated economically. The results showed a significant positive effect of the programme on profitability. Finally, the effect of fishing mortality adjustment, as a management tool, on profitability is also evaluated and it is shown that the reduction in fishing mortality causes a consequent increase on the NPV of profits from fishing activity. According to the results, one can consider the enhancement programme as a valuable addition to good management for the purpose of increasing economic performance when combined with appropriate management adjustments; in our case: reduction of the fishing mortality.