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6.

Redfish Distribution in the North Atlantic*

By WILFRED TEMPLEMAN Research Board of , Biological Station, St. John’s, Newfoundland

Abstract The distribution of Sebastes marinus and to a much caught near the surface in plankton nets but rather in lesser degree that of Sebastes viviparus are described. bottom trawls. Some redfish of these sizes have recently Although Sebastes marinus may be divided into Sebas­ been captured, however, in mid-water in the Gulf of tes marinus marinus, the ordinary redfish, and Sebastes Maine by means of a mid-water trawl. marinus mentella, the deep-water redfish, these two The redfish in the ICNAF area, which began subspecies have not, as a rule, been differentiated in as a special fishery in the in 1935, is now the available statistical and other data. Therefore, with carried out in all ICNAF subareas. The greatest catch regard to most of the information, it is possible to con­ was 159,000 metric tons in 1957. In the latter year the sider only the distribution of Sebastes marinus includ­ catch was 61,000 metric tons; followed ing both subspecies. The name redfish in this abstract by the USSR, 49,000; Canada, 21,000; Germany, refers to Sebastes marinus. 15,000; and Iceland, 13,000. Almost half the catch was Sebastes viviparus is well differentiated from S. obtained in Subarea 3 of ICNAF (the Newfoundland marinus by the greater number of scale rows in the subarea). The total redfish catch by the European latter. S. marinus mentella has a sharply projecting countries of the International Council for the Explora­ beak on the lower jaw and a large eye whereas in S. tion of the Sea (ICES) and the USSR increased marinus marinus this beak is absent, or present as a gradually (with some downward variations during rounded protuberance, and the eye is relatively small. wars) from 1,000 metric tons in 1907 to 294,000 in In S. viviparus the most anterior preopercular spine 1955, falling again to 251,000 in 1956. As a rule, before is directed backward. In S. marinus marinus of the 1955 over half of the catch came from the Icelandic Newfoundland area it is usually directed downward or grounds, with, until 1954, the Barents Sea, Bear Island, obliquely downward and backward. In S. marinus and Spitsbergen area usually next in importance. In mentella of the Newfoundland area this anterior pre­ 1954 the redfish catch in Greenland increased beyond opercular spine is usually directed obliquely downward that in the Barents Sea, Bear Island, and Spitsbergen and forward. area, and in 1955 the catch from Greenland was slightly Redfish larvae and young have been found abund­ greater than that from the Icelandic area. In 1956 antly in the Norwegian Sea, west and south of Iceland landings from the Greenland area again fell consider­ (including a great oceanic area south of Iceland and ably below those from the Icelandic area. In 1956, extending almost to ), in southern Green­ 50 % of the redfish was caught by Germany, 27 % by land waters, and in the Newfoundland, Grand Bank, Iceland, and 17 % by the USSR. The redfish catch in Gulf of St. Lawrence, Nova Scotian, and Gulf of Maine the West Greenland Subarea (1) of ICNAF amounted areas. Larval redfish tend to be most numerous to 14,000, 16,000, 32,000, and 14,000 metric tons in the above the deeper water bank and channel contours years from 1953 to 1956 respectively, and less than where adult redfish are abundant ; they have a pelagic 1,000 in earlier years, and is included both with the life of at least several months in the upper water layers. ICNAF and the ICES catches; otherwise the ICES Although in northern Greenland waters young redfish and USSR catches up to and including 1955 were from up to 45 to 50 mm are numerous in these upper water east of the ICNAF area. In 1956 the ICES landings layers, in the region from Newfoundland to the Gulf of include 13,000 metric tons taken in the Newfoundland Maine, redfish of 30 mm and over are not commonly subarea almost entirely by the USSR. Explorations by the research vessel “Investigator I I ” * The complete paper in Fish. Res. Bd. Canada, Bull. No. 120: 1-173. O ttaw a, 1959. of the Fisheries Research Board of Canada’s Station at 11,6 - 155 -

St. John’s from 1947 to 1954, and the commercial in the market, and thus when in equal or in slightly largely resulting from these otter- lesser abundance will usually be fished for instead of explorations, have shown redfish in the various deep mentella. Most of the redfish landed in Iceland and channels of the Gulf of St. Lawrence and in deep Europe, at least until recent years, have been of the water around the fringes of the banks in the New­ marinus type. foundland and Labrador area, as far northward as off The pelagic existence of numerous redfish, over the northern tip of Labrador. water much too deep for them to descend to the possibilities exist at least as far north as east of Hamil­ bottom, has been demonstrated for the Norwegian Sea. ton Inlet Bank and as far east as Flemish Cap. The presence of great quantities of redfish larvae over Sebastes viviparus lives in considerably shallower a wide area south of Iceland, in the absence of another water than Sebastes marinus. It occurs in numbers explanation, makes it plausible to believe that a large from the Finnmark coast of Norway southward along pelagic population of redfish may be present in this the Norwegian coast, in the northern North Sea, off area, but this belief cannot in any way be regarded as Scotland, Ireland, northern England, the Faroes, and proven. In the area from west of the tail of the Grand south and west of Iceland. Bank southward to Cape , there are no extensive Sebastes marinus is common in the Barents Sea to areas, at suitable redfish depths seaward of the bank Spitsbergen, along the Norwegian coast to the Faroes, slopes, with temperatures suitably low for redfish. It is Iceland, southern Greenland, Labrador, Flemish Cap, thus extremely unlikely that large pelagic populations the Grand Bank, the Gulf of St. Lawrence, and south­ of redfish exist seaward of the bank slopes in the south­ ward to the Gulf of Maine. Individual captures are ern part of the North-west Atlantic. reported to the north-east off West Spitsbergen at Lat. In comparisons of redfish catches by Newfoundland 80°06'N and Long. 11°17'E, off West Greenland north otter trawlers over the 24-hour period, sets carried out to Umanak Fjord in about Lat. 71°N, and the most more than an hour before sunrise or after sunset usually southerly record along the American continent is at had negligible redfish catches compared with the day­ Lat. 39°48'10"N, and Long. 71°48'40"W. light period. However, in some deep-water areas where Sebastes marinus mentella is distributed in the deep redfish were abundant, night sets, although consider­ water from south of Bear Island to West Greenland. ably smaller than daylight sets, were large enough to It is the common form throughout the Labrador, New­ make night fishing worth while. Although more data foundland, and probably the whole North American are desirable, there was a tendency in the 50 to 75 area. Sebastes marinus marinus is abundant in the fathom depths, and in the May to July catches at most shallower parts of the deep-water area from the Barents depths, to have morning and afternoon peaks in the Sea and the Bear Island grounds to West Greenland. catch. Between 76 and 160 fathoms the morning It is moderately abundant in limited portions only of catches were usually greater than the afternoon catches. the Newfoundland-Labrador area, but here also it In the darkest months, November to January, the occurs in shallower water than the deep-water mentella largest catches in the deeper water were in the late form. Bottom temperatures and depths suited to the morning or at noon. In the deepest water, 161 to 190 mentella form are continuous over the whole redfish fathoms, the highest catches were from late morning range from to the most north-easterly to the earlier part of the afternoon. Good catches part of its distribution off the Russian coast. The bot­ extended over a longer part of the day in the brightest tom connection between West Greenland and Baffin months with the longest period of daylight, May to Island and also the bottom areas in some of the chan­ July- nels to the east are suited in depth only to the mentella In the Newfoundland redfish catches from January form. Populations of the marinus form may be con­ to April mature females were much less abundant than nected only pelagically, across these channels. large males. In May and June mature females were The marinus type and probably also mentella are scarce at the shallower depths but plentiful in greater plentiful off West Greenland, and both are abundant depths. In July and August and in November and off East Greenland. On the basis of the available im­ December females were more numerous than males. perfect data, although mentella is present, marinus is During September and October mature females were the common form on the Norwegian grounds and in scarce at intermediate depths. Corresponding to the the Barents Sea. Marinus is present in the shallower lack of availability of mature females, the catch of and mentella in the deeper water near Iceland, whereas redfish per hour’s dragging was at a minimum in mentella is the common form on the Iceland-Faroe March. In Hermitage Bay, in catches between April Ridge and on the Bear Island deep-water grounds. It and December, mature females were considerably fewer must be remembered, for the European area, that than large males. In April, in fish of mature size 30 cm marinus lives shallower, is larger and is more favoured and over, females formed only 9 % of the catch. - 156 -

European, Icelandic, and Greenland commercial between 3° and 6°C. In the Icelandic area redfish are redfish are usually larger than those of North America. abundant mainly in the warmer water to the south and Redfish from the deep water off Labrador are also west and are usually scarce in the colder water to the large. Close analysis is impossible since usually the north and east. The decreasing quantities of redfish, marinus and mentella forms have not been separated found in proceeding southward on the seaward slope in the length-frequencies, but differences in the size at of Georges Bank, may be explained by the increasingly sexual maturity and in temperature and other environ­ high temperatures in redfish depths, and the existence mental factors in these areas, with resulting growth of a large population of redfish in the Gulf of Maine is differences, are doubtless factors of importance in correlated with moderately low sea temperatures over determining the limits of redfish size. most of the year. Both on the southern Nova Scotian At depths between 51 and 210 fathoms in the various Shelf area and in the Gulf of Maine the greatest divisions of the Newfoundland area, greatest redfish amount of redfish is coastward where the lowest tem­ catches were obtained in the 131 to 210 fathom range. peratures are to be found, or in deep water on the sea­ Most large catches occurred at depths where average ward edge of the slope where deep-water temperatures temperatures were between 3-4 and 5-0°C, but on the are lower than those in the shallower water. eastern slope of the Grand Bank the greatest catches Within the temperature range suited to redfish, were at a depth where the average temperature was depth is more important than temperature in the ver­ 2-l°C. When catches at individual depths are con­ tical distribution of the marinus and the mentella types sidered the larger catches were usually between 1 ° and of redfish. In the European area mentella lives in 5°C. The tendency to obtain large catches at these colder water than marinus, but in the North-west moderately low temperatures was particularly evident Atlantic marinus usually lives in colder water than at the greater depths whereas at the lesser depths (51 mentella. In the Flemish Cap area both forms live in to 90 fathoms) where redfish are smaller and fewer the water of the same temperature. In all three areas men­ best catch averages were at 5° to 6°C. In the New­ tella is in the deeper and marinus in the shallower foundland-Labrador region large populations of redfish water and the depth relationships of the two forms are exist only in or near areas where temperatures at red­ approximately the same in all three areas. fish depths are over 3°C. Many factors may be responsible for local concen­ In many parts of the bank slopes of the North-west trations of a redfish population. Among these factors Atlantic from Georges Bank to southern Labrador, are light, food, spawning cycle, temperature, bank redfish investigations in deep water during recent years slopes and ridges, depressions in the continental shelf, have demonstrated abundant redfish beyond the 200 stranding by currents, V-shaped areas, under-water fathom depth which until recently was the usual com­ projections of banks, and type of bottom. mercial fishing limit. These redfish, usually larger than The abundance of the marinus type in the European those of the same subspecies (mentella) from shal­ area coincides with the presence of a thick upper layer lower water, occur in apparent commercial abundance of moderately warm North Atlantic Current water, often to 250 fathoms, sometimes at 300 and occasion­ whereas this shallower water form is relatively scarce in ally at 350 fathoms. Individual redfish have been the North-west Atlantic, where the water at the levels captured at 451 to 500 fathoms. inhabited by marinus is typically cold. The mentella The data available agree with Tåning’s conclusion type is abundant in the North-west Atlantic where the that redfish are not plentiful except in areas where water at the greater depths suited to adults of this form temperatures between 3° to 8°C exist in depths of is generally moderately warm, and in the North- about 200 to 500 metres (110 to 270 fms). Over most central and North-east Atlantic the mentella type is of the North-west Atlantic the temperatures at these abundant, also, in areas where the warm North Atlantic depths in areas of redfish abundance are usually water extends deeply into the mentella range.