Codfish (family Gadidae) are a family of bottom-feeding fish that live in cool or cold seas, mostly in the Northern Hemisphere. There are about 21 genera and 55 species of codfishes. The most commonly utilized marine habitats are inshore waters and continental shelves, generally in depths of less than about 300 ft (100 m), but sometimes considerably deeper. Codfishes are voracious predators of smaller species of fish and invertebrates . Some species of codfish are of great economic importance, supporting very large fisheries.
The Gadidae family is divided into two subfamilies. The Gadinae includes cod (e.g., Atlantic cod, Gadus morhua) and haddock (Melanogrammus aeglefinus), while the Lotinae includes hake (e.g., silver hake, Merluccius bilinearis), rockling (e.g., silver rockling, Gaidropsarus argentatus), and burbot (e.g., the freshwater American burbot, Lota lota).
Atlantic cod and its fishery
The economically most important species of codfish is the Atlantic cod, which has supported one of the world's largest fisheries. This species is common on both sides of the Atlantic Ocean. The Atlantic cod extends from Novaya Zemlya and Spitzbergen in the northeastern Atlantic, to Baffin Island and central Greenland in the northwestern Atlantic. The Atlantic cod is found as far south as the Bay of Biscay in western Europe , and coastal North Carolina in North America . In the western Atlantic, the Atlantic cod is most abundant on the Grand Banks, a large region of open-ocean shelf east of Newfoundland.
Atlantic cod are ravenous feeders on a wide variety of prey found on the sea bottom or in the water column. Fry and juvenile cod eat smaller invertebrates and fish larvae. The most common prey of adult Atlantic cod is small species of fish, but cannibalistic feeding on smaller size classes of its own species is known to occur.
The Atlantic cod has long been the target of European fishers, and this species was one of the first natural resources to be heavily exploited by European settlers in the Americas. The extraordinarily large cod populations of the Grand Banks and the northern Gulf of Saint Lawrence were noted during the exploratory voyages of the Cabot brothers, who sailed on behalf of England during the late 1490s. By 1505, many Portuguese and Basque fishers were exploiting the bountiful cod resources of the New World. By 1550, hundreds of ships departed every year from European ports for the northwest Atlantic in search of cod, which were taken in large quantities, preserved by salting or drying, and transported to the kitchens of western Europe. By 1620, there were more than 1,000 fishing vessels in the waters off Newfoundland, and about 1,600 in 1812.
During this early stage of the cod fishery in the northwest Atlantic, fish were typically very large, commonly 3-6 ft (1-2 m) long and weighing more than 220 lb (100 kg). However, because of the long history of heavy exploitation of Atlantic cod, such large fish are very rare today.
During the eighteenth and nineteenth centuries the cod fishery on the banks off Newfoundland was an unregulated, open-access enterprise, involving large numbers of ships sailing from Europe, Newfoundland, Canada, and New England. In addition, flotillas of smaller, local boats were exploiting near-shore populations of cod. Most of the fishing during these times was done using hand lines and long lines, which are not very efficient methods. Still, the substantial fishing effort caused noticeable depletions of many of the near-shore cod stocks.
During the twentieth century, especially its second half, the new technologies allowed a much more intensive exploitation of the stocks of Atlantic cod. A variety of highly efficient trawls, seines, and gill nets have been developed, and their effective deployment is aided by fish-finding devices based on sonar technology. Moreover, storage and processing capacities of ships have significantly increased, which permits large vessels to stay at sea for long periods of time.
The 1960s saw the largest harvests of cod in the northwest Atlantic, as a result of efficient technology and open-access and unregulated fishery. The total catch in this region in 1968 was more than two million tons. These huge catches were not sustainable by the cod population, and the stocks of Atlantic cod began to collapse by the 1970s.
In 1977, the Canadian government began to manage fisheries within a 200 mi (320 km) wide zone around its coast. This was mostly accomplished by controlling access and allocating quotas of fish, especially cod, the most important species in the fishery. These conservation efforts led to small increases in cod stocks and catches. However, during the late 1980s and 1990s, the cod stocks suffered a more serious collapse. Because the populations of mature cod capable of reproducing the species are small, the stocks will probably recover quite slowly, despite the huge reductions in fishing beginning in 1991, and a ban on cod fishing in 1992. The fishing moratorium recognizes the sad fact that one of the world's greatest renewable resources, the stocks of cod in the northwest Atlantic, had been over fished to commercial extinction . This damage has been long lasting—there was still not much recovery by the year 2000.
Undoubtedly, the collapse of cod stocks was mostly caused by over fishing, that is, exploitation at a rate exceeding the productivity of the cod population. The over fishing occurred because of economic greed, faulty fish-population models that predicted excessively large quotas, and because politicians set fishing quotas exceeding those recommended by their fishery scientists. Moreover, this over fishing occurred along with other environmental changes that may have exacerbated the effects of the excessive harvesting. In particular, several years of unusually cold waters off Newfoundland and Labrador may have reduced spawning success, so the heavily fished population was not being replenished. Other factors have also been suggested, including a rapidly increasing population of seals . However, this particular seal species does not consume much cod and is therefore not considered a significant factor in the collapse of cod stocks. Unregulated fishing is clearly the major factor.
Fortunately, Atlantic cod populations, while low, are not threatened with extinction. In 1994, spawning schools of fish were once again observed in the waters off Newfoundland. If the regulating authorities maintain the moratorium on cod fishing, and if they subsequently regulate and monitor the fishery, then there is hope that this great natural resource will again provide food for humans, but this time in a sustainable fashion.
Freedman, B. Environmental Ecology. 2nd ed. San Diego: Academic Press, 1995.
Whiteman, Kate. World Encyclopedia of Fish & Shellfish. New York: Lorenz Books, 2000.