Assessment of mangrove status and fish community in Pangani estuary

Abstract

A study was conducted in Pangani mangrove forest aimed at assessing mangrove vegetation structure, regeneration capacity and associated fish community. A total of 753 ha of mangrove area were assessed. A 100 m² plots and sub plots of 25m² were established for assessing mangrove regeneration capacity. Fish community assessment was conducted along the estuary starting at 1000 m from river mouth towards upstream. Fishing was done adjacent to the area where transects for mangrove study were established. A monofilament gillnets and seine net with a dimension of 50 m length and 1.5 m width and a mesh size of 2.5 inches were used. Pangani mangrove forest is composed by eight species dominated by Avicenia marina in terms of relative density (29%), relative frequency (29%) and importance value (0.69). Avicenia marina, Rhizophoramucronata and Ceriopstagal had the highest regeneration capacity for juveniles class one (JCI), two (JCII) and three (JCIII) respectively both in terms of dominance and coverage. The highest DBH, height and basal area were shown by Lumnizeraracemosa (49.89±89 cm), Rhizophoramucronata (11.99±1.28) and Lumnizeraracemosa (0.25±0.11 m2) respectively. Seventeen fish species from fifteen families were recorded during this study. Predominant fish families in terms of number were Clupeidae (62%) followed by Mugilidae (13%) and Hemiramphidae (9%). The highest and least contributions in terms of weight were Clupeidae (68%) and Engraulidae (0.19%) respectively. This study indicated that predominant mangrove species have also high regeneration capacity. Furthermore, length frequency distributions of the predominant fish species confirm breeding and nursery role played by mangrove forest. It is therefore recommended that management of Pangani mangrove forest should be strengthened to enhance fisheries production.