Empirical Yield-effort Models for Bangladesh Inland Fisheries

Abstract

Aims: To support community-based fisheries management (CBFM) of inland fisheries resources in Bangladesh.  Study Design: An investigation into the impact of the nationwide CBFM Project and four alternative yield-effort models were fitted to the catch (yield) and effort data. Place and Duration of Study: The study comprised community managed fisheries (sites) located in five different inland water habitat types in Bangladesh for the period 1997-2005.  Methodology: Using data compiled for this impact assessment, the aggregated yield-effort response is examined in more detail among different habitats as a means of providing local managers with guidance on controlling fishing effort. Results: An effort-based analogue of the ad hoc ‘F0.1 strategy’ E0.x is proposed as a management reference point to be used with this model. Estimates of fishing effort at x=1 and 2 and corresponding yield () and catch rates () are also provided for the five habitats examined. Values for x of between 1 and 2 give rise to a CPUE of approximately 40-50% of the predicted maximum CPUE. Catch rates may be used to monitor progress towards the selected reference point. As a general ‘rule of thumb’ for the fisheries examined, catch per fisher, averaged over the year, corresponding to the reference point is approximately 0.5 kg d-1 when x=1 and 0.7      kg d-1 when x=2. The asymptotic model provided the best description of the yield-effort response for floodplain and Haor beel habitats and the sigmoid model provided best description of the data for the Open beel and River habitats. The Schaefer model provided the best description of the data for closed beel habitat. However, among all habitats the Fox model was the least favoured model. Conclusion: Both the asymptotic and the sigmoid model each provided the best description of the yield-effort response within two habitats. The Schaefer model provided the best description of the data for closed beel habitat. The study has provided evidence that across habitat favoured an asymptotic yield-effort model (Akaike weight 0.85) as being the most generally applicable.