Development of Fisheries for Traditionally Exploited Species

Abstract

Present catches of traditional marine resources are characterized by a great predominance of pelagic species, especially among the fishes. Since World War II the catch of pelagic fishes has increased by 27.5 million metric tons (mmt) and now constitutes about 70% of the total; production of demersal species has increased by 10.5 mmt. Over 60% of the catch is of plankton-feeding organisms, a little over 25% is predacious fishes, and only 4% bottom feeders.Of the world catch of aquatic organisms in 1970, 63.4 mmt (90%) was fish, 5.2 mmt invertebrates, about 1 mmt whales, and 0.7 mmt seaweeds. About 90% of this catch was from the ocean. From 1950 to 1970 marine catches rose from 16.1 to 55.8 mmt, while those from fresh waters increased from 2.4 to 7.6 mmt.About 70% of marine catches are made up of seven families of fishes, with the Engraulidae having by far the leading role — about 24%. Next in order come Clupeidae and Gadidae. Pleuronectidae, Scorpaenidae, Sparidae, etc. are less important. Only 5.06 million tons (8%) of the catch is of invertebrates. Of these 65–70% are molluscs (mostly squids), 30% crustaceans, and 1% echinoderms.Species such as cod, redfish, rockfish, flounders and clupeids in most areas of the northern hemisphere have reached or almost reached their limit. The greatest increase in demersal catches can be expected from the Falkland–Patagonia area, where landings of hake, poutassou, grenadier, and some other species could reach 3 million tons, and in New Zealand and Australian waters the take may rise to 4 or 5 mmt. Pelagic fishes may eventually yield catches of the order of 17–20 mmt, including sardines, anchovies, mackerels, carangids, sauries, smaller tunas, myctophids, and squids. In all, a future catch of 52 mmt of pelagic species and 30 mmt of demersal species may be possible.In addition, perhaps 1 mmt can be expected from fishing in depths of 800–1200 m for macrurids, rockfsishes, halibuts, etc. The yield of demersal invertebrates may reach 2.2 mmt, anything more would require extensive aquaculture.A total potential catch of 90 mmt of familiar species is estimated — not including krill, other zooplankton, or seaweed. This figure implies adequate and effective conservation regulations, without which catches can be expected to decline rather than increase.