Native and introduced fish caught with gillnets in Limboto Lake, Gorontalo Province, Indonesia

Inland fisheries are important for food security, while freshwater fish diversity is under increasing threat around the world, and both are often poorly documented. Limboto Lake, in Gorontalo Province on the northern arm of Sulawesi, is one of 15 priority lakes in Indonesia. Time-series data are important for sustainable management, but often unavailable, leading to shifting baselines. Data on the catch volume and species composition of buili gillnet fishers in Limboto Lake were collected over 12 weeks from February to April 2011 at four sampling sites with a total of 32 gillnet fishing trips. The 1,949 fish caught included 46 native fishes and 1,903 introduced fishes. The dominant species were tilapia (50% Oreochromis niloticus; 33% Oreochromis mossambicus), followed by Java barb Barbonymus gonionotus (14%). Small numbers of striped snakehead Channa striata, mullets Planiliza spp., and spotted scat Scatophagus argus were also caught. Native species, including traditional food fishes such as gobies (Giuris sp. and Glossogobius sp.), were rare or absent. These historical data show that the introduction of non-native species had adversely affected the ichthyofaunal biodiversity of Limboto Lake 12 years ago, highlighting the need for biodiversity monitoring.