Many marine mammals, like the steller sea lion, depend on forage fish for half of their diet. (Photo: NOAA/Lenfest Ocean/FIS)
Contributions of forage fish worldwide explained
Tuesday, September 11, 2012, 22:40 (GMT + 9)
A just-published study provides a first-time analysis of the value of forage fish, which are small, schooling species such as sardines, herring, and anchovies. Three kinds of contributions of forage fish were estimated: as direct catch, as food for other commercially important fish, and as an important link in the food web in marine ecosystems.
The analysis showed these small fish contribute a total of USD 16.9 billion, as both direct catch and food for larger fish, to global fisheries annually, representing 20 per cent of the global catch values of all marine fisheries combined. Additionally, the scientists found in 75 per cent of the ecosystem models analyzed, at least one of the highly dependent predator species of forage fish, such as seabirds, marine mammals, depended on these fish for half or more of its diet, and in 30 per cent of the models analyzed, forage fish made up three-quarters of the diet for at least one predator species.
A team of scientists led by the Institute for Conservation Science at Stony Brook University examined these contributions of forage fish through a compilation and synthesis of 72 published Ecopath models from around the world. Ecopath models are a type of food web model that can be used to estimate the direction and strength of interactions among species within an ecosystem.
This analysis identified ecosystems that are likely to have highly to extremely dependent forage fish predators, which may assist in ecosystem-based management efforts that consider both commercial fisheries and effects to threatened or endangered species.
"In addition to their value to commercial fishing and other industries that depend on them for their products, forage fish play valuable roles in global ecosystems while they are still in the water," said Dr Ellen K Pikitch, co-lead author and executive director of the Institute for Ocean Conservation Science and professor at Stony Brook University. "By quantifying the overall contributions forage fish make globally to both economies and ecosystems, we can evaluate the trade-offs of various uses of forage fish."
"The global contribution of forage fish to marine fisheries and ecosystems," recently published online in the journal FISH and FISHERIES, synthesized data obtained from multiple independent studies of marine ecosystems around the world that include forage fish. This research was supported by a grant from the Lenfest Ocean Programme, and the research was conducted under the auspices of the Lenfest Forage Fish Task Force.
The analysis showed the value of the direct catch of forage fish is USD 5.6 billion. The highest forage fish catches were found in the Humboldt Current models where the Peruvian anchoveta fishery operates.
The value of fisheries that are supported by forage fish is twice that of the direct catch at USD 11.3 billion. The dollar amount of the contributions of forage fish to industries such as tourism and recreational fishing were not estimated for this study, and would increase the estimated economic value of the fish as prey species.