Freshwater Fish Assemblages and Water Quality Parameters in Seven Lakes of San Pablo, Laguna, Philippines

Abstract

An ichthyofaunal survey was conducted to characterize the diversity and abundance of freshwater fish assemblages in Seven Lakes of San Pablo, Laguna, Luzon Island, Philippines. This two-year study collected 5,166 fish samples, belonging to ten species and six families. Out of ten fish species, three were classified as native (Leiopotherapon plumbeus, Glossogobius sp., and Giuris margaritacea). Nile tilapia (Oreochromis niloticus) and silver therapon (L. plumbeus) were the two most abundant fish species which comprised about 75% of the total fish collected. Overall, native fish species comprised about 41% of the total abundance. Shannon-Weiner’s diversity varied from 0.82–1.64, indicating fairly low diversity. Bray-Curtis similarity recorded high resemblance rate (>56%) among the studied lakes. Various water quality parameters including dissolved oxygen, water surface temperature, and pH were within the ideal level for the growth and survival of tropical fishes, albeit high turbidity readings based on Secchi disc visibility depth were observed. The lakes were found to have a low number of freshwater fish species, albeit largely composed of non-native fish species, principally O. niloticus. The baseline information from this study can be useful for future conservation and rehabilitation efforts for the lakes.