Bottom-up drivers of global patterns of demersal, forage, and pelagic fishes
The interaction between aquaculture and fisheries is just one aspect of the trade-off between the multiple benefits that forage fish bring to people, marine ecosystems, economies and industries. Given the challenges of non-market valuations and limited knowledge of marine biodiversity, we have identified multiple beneficiaries of forage fish, all of which come from different categories of benefits (social, economic and environmental) resources. Pikitch's study addressed a key knowledge gap in this area and estimated the value of forage fish at US$16.9 billion, including the value of direct catches and the value to predators that depend on it. It does not categorize direct catch values per user (e.g., human consumption or non-edible use by aquaculture and ranching), nor does it quantify the contribution of these species to coastal tourism. There is value beyond these monetary estimates that are important to health and social welfare. These values include cultural and spiritual values of marine resources to indigenous communities, and amenity values arising from restored and healthy marine ecosystems. In addition, we assess the ecological value of forage fish species that support a range of marine predators, highlighting the intrinsic value of all species, including forage fish themselves that rely on healthy functioning ecosystems for survival. Forage fish, also called prey fish or bait fish, are small pelagic fish that are hunted for food by larger predators. Predators include other large fish, seabirds and marine mammals. Typical marine forage fish eat plankton near the base of the food chain, often by filter feeding. These include, in particular, fish of the order Aquarius (herring, sardines, alice shad, hirsa, menhaden, anchovies, sprat), but also smelt such as halfbeak, silverside and capelin, and others such as gold-banded fusiliers. Foraging fish compensate for their small size by forming schools. Some even swim in synchronized grids with their mouths open so that they can filter plankton efficiently. These schools form huge flocks that migrate along the coast and across the open ocean. Swarms are a concentrated energy resource for large marine predators. Predators are highly concentrated in herds, acutely aware of their numbers and whereabouts, and undertake thousands of kilometers of unique migration to connect or remain connected to them. Mainly contained in plankton, marine primary producers produce food energy from the sun and feed the marine food web. Forage fish transfer this energy by eating plankton and becoming food for the higher predators themselves. As such, forage fish occupy a central position in the food web of oceans and lakes. Fisheries sometimes catch baitfish for commercial purposes, but primarily for use as baitfish for farmed animals that eat fish. Some fisheries scientists have expressed concern that this could affect the predatory fish populations that depend on them. And other small schooling forage fish such as capelin, smelt, sundance, halfbeak, walleye, butterfly fish and scorpion fish juveniles. Herring is an excellent forage fish and is often sold as sardines or sardines. The term "bait fish" is a fishing term and is also used for a type of bait that is not a real fish but plays an important role as food for predatory fish. Invertebrates such as squid and shrimp are also called "edible fish". Even tiny shrimp-like creatures called krill are small enough to be eaten by other forage fish, but large enough to eat the same zooplankton as forage fish, and are often classified as "forage fish".