Fishers’ Perspectives: the Drivers Behind the Decline in Fish Catch in Laguna Lake, Philippines

Aquatic ecosystems are strongly affected by global change. Fishers hold local ecological knowledge (LEK) that is especially relevant for improving our understanding of aquatic ecosystems that experience major environmental changes while also providing crucial ecosystem services. This research explores the perceptions of the ecological changes in Laguna Lake (Philippines) among local fisherfolks. In 2019, we conducted 30 semi-structured interviews with fisherfolks with up to 60 years' experience. They reported catching 31 fish species and one shrimp genus as a staple food and income source, with more than one-third of the species being exotic or introduced. The fisherfolks noted repeated fish kill events and dramatic changes in their catch such as fewer and smaller fish. Also noticeable were the widespread catch of knifefish, a comparably newly introduced species, and the fact that all native fish species were reported to be less often caught now than in the past. This included the reduced catch of talilong (mullet), dalag (snakehead), and ayungin (silver perch). Locals emphasized various drivers behind these changes, which are linked to one another in complex interrelationships. Invasive species, the deterioration of fish habitats, and increased water turbidity were cited as the main drivers. Interviewees highlighted an additional link between declining catches and the loss of aquatic plant diversity, which has been understudied in Laguna Lake and has not been the focus of regional policy efforts. The empirical evidence provided by the fisherfolks enhances earlier existing scientific evidence of this aquatic ecosystem as well as highlights the importance of contributions coming from different knowledge systems.