Fish Diversity in Mangrove Conservation Area of Labuhan, Bangkalan, East Java - Indonesia, with Emphasis on Important Fishery Species

Mangroves are one of the most productive ecosystems which support biodiversity of aquatic invertebrate and vertebrates. Many local fishermen in Labuhan village, Sepulu, Bangkalan - East Java depends on the existence of mangrove for fisheries production, including economically important species. This study aimed to determine the diversity of fish within mangrove (the inner mangrove/IM) and coastal water in front of mangrove (the outer mangrove/OM). Samplings with several active and passive fishing gears (scoop net, gill net, fish trap) were conducted three times during high tide periods in June 2021, October 2021 and July 2022. The fish diversity analyzed with the Shannon-Wiener (H') diversity index while similarity of fish communities was approached using the Sorensen similarity index. A total of 36 fish species were identified, with 23 species recorded from IM and 22 species from OM. The IM always has higher species richness and abundance, that is 20.33±0.58 species and 125.33±26.27 individuals compared to the OM with 13.33±3.06 species and 36.67±13.01 individuals. The IM also has a relatively higher value of H' (2.49±0.06) than OM (2.207±0.18). The value of Sorensen index was 0.419 with only 9 shared species in both areas. The most dominant species in the IM is Mozambique tilapia (Oreochromis mossambicus) while in OM there is Singapore glass perchlet (Ambassis kopsii). Sixteen species are considered having economic value; with most of high economic important species, e.g. Milkfish (Chanos chanos), Greenback mullet (Planiliza subviridis), Great barracuda (Sphyraena barracuda) and Barramundi (Lates calcarifer) were usually caught at juvenile and/or immature stages.