Patterns of fish community structure in protected and non-protected marine areas in Tanzania mainland

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Sokoine University of Agriculture


Over the years Marine Protected Areas (MPA) have excelled in protecting marine biodiversity contrary to other less protected areas. However, information on the performance of protection on the condition of fish stocks is less well documented in Tanzania. The survey was done on fish landing sites located in Tanga and Mtwara regions to assess patterns of fish community structure particularly on the fish abundance, species diversity, growth patterns, and maturity stages based on catches landed from sites differing in protection status. The fish abundance from protected areas was significantly lower than in non-protected areas (p=0.002). Species’ diversity was relatively higher in catches from non-protected (H=2.742) than in protected areas (H=2.232). High percentage of species (63.24%) exhibiting negative allometric growths were observed in catches landed from non-protected areas. Further, large number of matured fish was observed in catches from protected areas compared to non-protected areas (p<0.01). These indices are useful indicators of the performance of MPAs. The observed negative allometric growth in fishes and low fish maturity in the non-protected area strongly suggest the role of high or uncontrolled extractive pressure and disturbances caused by the fishing gears on the fish stock. Continued high extraction may induce a decline in general fish size due to constantly selecting for large trait fish stock, potentially causing evolutionally change in morphological traits. In contrast the lower abundance and species diversity from the protected area is reflective of low catch effort, a common strategy of regulating fishing pressure in MPA rather than indicating the actual diversity in the fish stocks in these protected waters. Based on these findings more regulatory strategies of fishing in the open waters are recommended to allow for more time for the fish to attain the appropriate size and to ensure the effective protection of marine resources.




Fish growth patterns, Fish maturity, Coral reefs, Fisheries resources, Tanzania mainland