Trophic flow structure of the Danajon ecosystem (Central Philippines) and impacts of illegal and destructive fishing practices

- A trophic model of a shallow tropical municipal fisheries system was constructed.
- The fishery is dominated by fish and invertebrate species of low trophic levels.
- Overall, the fishery functions as the main driver of system dynamics.
- The illegal and destructive fisheries account for nearly a quarter of the catches.
- Their removal could lead to a more equitable sharing of fisheries economic gains.

A trophic model of the shallow Danajon Bank, in the Central Visayas, Philippines was developed using a mass-balance approach (Ecopath) to describe the system characteristics and fisheries interactions. The Ecopath model is composed of 37 functional groups and 17 fishing fleet types reflecting the high diversity of catches and fishing operations in the Danajon Bank. Collectively, the catch is dominated by lower trophic level fish and invertebrates as reflected in the mean trophic level of the fishery (2.95). The low biomass and high exploitation levels for many upper trophic level groups and the little evidence for strong natural physical disturbances suggest that top-down fishery is the main driver of system dynamics. The mixed trophic impacts (MTI) analysis reveals the role of the illegal and destructive fishing operations in influencing the ecosystem structure and dynamics. Furthermore, the illegal fisheries' estimated collective annual harvest is equivalent to nearly a quarter of the entire municipal fisheries catch in the area. Improved fisheries law enforcement by the local government units to curb these illegal and destructive fishing operations could substantially increase the potential gains of the legal fisheries.