Diversity and Distribution of Freshwater Fish Assemblages in Lake Taal River Systems in Batangas, Philippines

An ichthyofaunal survey was conducted to evaluate the diversity and distribution of freshwater fishes in Looc, Magapi (inlets), and Pansipit (outlet) rivers surrounding Lake Taal (Batangas, Philippines) during the wet (July) and dry season (January) of 2011. The study collected 3,342 individuals comprising 37 species (19 families). In terms of fish species richness, 36 species were identified in Pansipit, whereas Looc and Magapi had 21 species each. The fish samples were mostly included eurayhaline, secondary freshwater fishes. The three most abundant groups were eleotrids, cichlids, and gobiids. Shannon-Weiner’s diversity indices ranged from 2.17–3.05, which suggest that the studied rivers were moderately to slightly impacted. Significant differences in the composition and abundance of native and introduced fishes for the two sampling seasons were also observed (P<0.05), with native species being generally more diverse and abundant than non-native species. A high similarity level (>76%) was computed in the abundance data among the studied rivers. Canonical correspondence analysis identified the distance to the adjacent sea, depth, and vegetation as the most important environmental parameters influencing the distribution of fish assemblages. Baseline dataset from this study can be coordinated to concerned entities as a rational basis for future conservation and rehabilitation endeavors of Lake Taal river systems.