Greenland Cod

Head relatively broad; interorbital space 18 to 25% of head length. Predorsal distance more than about 33% of length; anterior part of swimbladder with 2 relatively short, horn-like extension. Colour: dorsally brown to grey with spots or vermiculations, ventrally paler.

Found around the rim of the North Pacific, from the Yellow Sea to the Bering Strait, along the Aleutians, and south to about Los Angeles. Rather rare in the southern part of its range.

Reaches 1 m total length.

Lives mainly along the continental shelf and upper slope of the North Pacific in the areas bordered by Korea and the western Chukchi Peninsula in the west, and Norton Sound and Oregon in the east.Its bathymetric range extends from shallow water (10 m) to about 550 m, but it is mostly between 100 and 400 m in the Gulf of Alaska and the Bering Sea.Some cod are assumed to be pelagic over deep water. The distribution in the eastern Bering Sea varies between years and seasons within years.The driving environmental variable behind the changes in distribution appears to be water temperature, with such biological factors as year-class abundance and age composition, and probably spawning and feeding migrations also playing important roles. Spawning migrations have been definitely linked to annual changes in temperature of the ocean in various parts of the geographical range. Pacific cod does not undertake migrations as extensive as the Atlantic species but moves only for short distances, such as to and from the shore, or from one bank to the other within a limited region. In summer, schools are small and distinct, contrarily to the large aggregations formed by the Atlantic cod. In the western Pacific, there appear to be two general types of schooling behaviour in cod of similar size and state of maturity: a school that is more or less permanent on the grounds and a school that moves continually. These two types of schools could be observed along the western shores of Kamchatka in two parallel rows, one at depths of 10-50 m, the other at 70-100 m. Near the end of September, or at the beginning of October, fish of the shallow row retreat to greater depths where they mix with those of the deeper row, and subsequently, they all proceed to 150-250 m depth where they remain for the winter. In the eastern Bering Sea and regions of Kamchatka and the Sea of Okhotsk, Pacific cod move off the inner and central shelf regions as summer ends, concentrate in deeper water on the outer shelf and along the shelf edge during winter (in response to the autumn-winter drop in temperatures in the littoral waters), migrate back toward the inner shelf as the ice pack recedes northward in the spring (post-spawning/feeding migration), and are broadly dispersed over much of the inner and central shelf, as well as the outer shelf and along the continental slope, during the summer. Age and size at first maturity vary with areas, the southern stocks maturing at an earlier age. They are, respectively, for males and females: 2-3 years and 40 to 44 cm off Washington, 3 years and about 50 cm in the Gulf of Alaska and in the Bering Strait, and 5 years and about 67 cm off Rebun Island, Hokkaido. In the eastern Bering Sea, the proportion of females increases with size from 43.3% at 10 to 20 cm length to 61.6% at more than 60 cm. The overall sex ratio and size-specific differences for cod in the eastern Bering Sea are similar to those for the cod in the northwestern Bering Sea, where the sex ratio is nearly 1:1, with males dominating in the younger age groups, and females in the older age groups. Fecundity ranges from 860,000-6,400,000 eggs per individual, depending also on environmental conditions: in the far eastern areas, the range is 1,400,000-6,400,000 eggs; in Hokkaido waters, 3,000,000-4,000,000 eggs; in Mutsu Bay (northernmost Honshu), 1,500,000-2,000,000 eggs. In the Straits of Georgia (southern British Columbia), females of 60-78 cm produce 1,200,000 to 3,300,000 eggs; in the Gulf of Alaska the fecundity ranges from 860,000-3,000,000 eggs, and in the Bering Sea, from 1,000,000-2,000,000 eggs. Females spawn only once each season. The eggs are demersal and slightly adhesive. The spawning season extends from winter to early spring. In the western Pacific, around the Commander Islands and along the coast of Siberia, spawning occurs from January to May. Spawning time differs between Japan and the Sea of Okhotsk because of differences in the cycles of the oceanographic climate: in the warmer regions such as Japan and Korea, the fish remain at greater depths during summer (up to 200 m), and when temperatures drop during autumn, they move into shallow water, and spawn during winter; in more northern regions, such as the Sea of Okhotsk, where the temperatures of littoral waters are very low during winter, cod move to considerable depths for over-wintering and spawn in March-April. Off West Kamchatka, cod move away from the ocean floor at the approach of the spawning period and concentrate at an intermediate depth. Spawning in the eastern Bering Sea is expected to take place within the period of January to April, when water temperature is higher than 0°C; the optimum temperature for hatching and survival is considered to be 5°C. Along the Alaska Peninsula and westward, spawning takes place in the warmer waters of the outer continental shelf and slope or in protected bays and adjacent ice-free waters. Off British Columbia and Washington, spawning areas in shallow water are located at about 53°N, where seasonal minimum bottom temperatures occur on inshore banks during winter. However, reproduction may be adversely affected by the relatively frequent occurrence of warm winters in this area. In the Gulf of Alaska, cod spawn from January to March along the continental slope of Alaska Peninsula. It is hypothesized that spawning of Pacific cod must take place over a shorter period of time than that of the Atlantic species because of the greater instability in the Pacific marine temperatures. Growth of Pacific cod is rapid during early stages. In the eastern Bering Sea, it has not been well identified because of problems in ageing the fish in the region. The southern Pacific stocks grow substantially faster than stocks of the colder regions of the North Pacific (such as the Bering and Okhotsk Seas), and growth is continuous throughout the year. Southern Pacific cod also mature at an earlier age and have a shorter life span (6-7 years). In Hecate Strait (northern British Columbia) cod length at age 1 is 23 cm; at age 2 it is about 44 cm; and the theoretical maximum length is 94 cm. Corresponding lengths, in the Straits of Georgia are 26, 49, and 76 cm; in the Bering Sea, 27.5, 43, and 84.5 cm (age 8), and in the Gulf of Alaska, 28.5, 47, and 85.5 cm. Although the fish usually grow to a maximum length of 85 cm, the greatest recorded length is 120 cm. The life span is normally 8-9 years, although in the western Pacific, they can live up to 12 years. Pacific cod appear to be indiscriminate predators upon dominant food organisms present. They evidently feed very little when they are close to spawning. The diet of adults includes fish, octopuses, and large benthic and bentho-pelagic crustacea such as the Kamchatka crab and shrimps. The fish species consumed include saffron cod, pollock, smelt, and herring, as well as flounders, cottids, salmon and sardines.

The total catch reported in the FAO Yearbook of Fishery Statistics for 1987 totalled 441 778 t, of which 270,072 mt have been taken in Northeast Pacific and 159,767 mt in Northwest Pacific. The Japanese catch in Northeast Pacific (area 61), which had traditionally accounted for the largest component of the total landings of this species, has decreased substantially (because of intense exploitation) since the mid seventies, while the Russian Federation (formerly USSR) catch has shown a rapid increase in recent years. It should be noted that the abundance of Pacific cod has increased substantially since 1977 as a result of the recruitment of the exceptionally strong year classes for 1977-1978 and the good year classes of 1982 to 1985. In Nortwest Pacific (area 67) catches of Pacific cod by the USA trawl fishery and joint-venture fisheries increased from less than 1,000 t in 1979 to nearly 91,000 t in 1984 and reached 430 196 t in 1995. Pacific cod is often taken incidentally by pollock and flatfish fisheries, and in Korea it is exclusively a by-catch of other commercial fisheries. In northeastern Pacific, the major types of gear used are trawls, but also longlines, troll and handlines. In Japan and Bering Sea, also Danish seines, and pair trawl and stern trawl are used. In all areas, the importance of cod in the catches declines with depth. Depths of greatest cod occurrence were generally between 91 and 273 m. There are higher proportions of large fish in the British Columbia and southeastern Alaska regions than in the Gulf of Alaska and the Bering Sea. In the eastern Bering Sea, cod are taken primarily on the outer continental shelf (about equally divided between the areas southeast and northwest of the Pribilof Islands), with highest catches occurring near the shelf edge. Pacific cod has a high growth rate and high natural mortality and can support heavy exploitation. The total catch reported for this species to FAO for 1999 was 402 244 t. The countries with the largest catches were USA (237 679 t) and Russian Federation (101 929 t). The catch is used mostly for filleting for subsequent production of fish sticks and fillet blocks.