Abstract:
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.
