-- QL 626 L"brary I MPO - Bibliothèque t1 1 U5313 no.17 \\\\\ \\\\\ \\\\\ \\\\\ \\\\\ \\\\\ \\\\\ \\\\ \\\\ c.2 12064603

- Atlantic Mackerel 2

he Atlantic mackerel (Scomber Distribution and migration T scombrus) is a handsome fish - Atlantic mackerel are found over the THE ATLANTIC streamlined and fast swimming, with continental shelf on bath sides of the dark tiger-like striping on its blue and Atlantic Ocean. The European race MACKEREL silvery body. extends from Norway to Spain, as well A member of the family Scom- as into the Mediterranean and Black bridae*, mackerel have a fatty flesh seas. In the northwest Atlantic, with a delicious flavour and are a mackerel range from North Carolina favourite of some Europeans, espe- to Labrador. cially the Portugese, who have fished Atlantic mackerel in the northwest them for centuries. Atlantic comprise two populations: Despite these favourable qualities the southern contingent spawning and a good reputation on European between Cape May and Long Island in tables, consumer demand is relatively April and May and the northern con- low in Canada. Many domestic cus- tingent whose main spawning area is tomers do not know what they are the southern Gulf of St. Lawrence in missing. June and July. Most of the Canadian The majority of the Scombridae are catch is taken from the northern of tropical origin, but the Atlantic population, although some schools mackerel is found in abundance in belonging to the southern population northern waters of the Atlantic. may appear on the Scotian Shelf in the Another member of the family, the summer. Canadian fishermen have Atlantic chub mackerel, only occasion- never fished mackerel intensively ally ventures as far north as the Mari- because of the lack of markets. With time Provinces. extension of jurisdiction and the disap- pearance of foreign fishing, the mack- Description erel stocks are now rebuilding and are The Atlantic mackerel is shaped for being lightly exploited. Recent analyses swimming swiftly with a minimum of indicate catches of up to 150,000 effort. lts body is slender, tapering at metric tons could be safely harvested. the tail and snout. The pectoral fins, Mackerel prefer a water temperature found just behind the gill openings, are between 9° and 12°C, and migrate extended like hydrofoils during slow annually, probably in response to swimming; at high speéds, they are seasonal changes in water temperature swept back and completely pressed to in the northwest Atlantic. The main the body. The pelvic fins, located just known overwintering area is the con- below the pectorals, are extended only tinental shelf south and southwest of during turning. Georges Bank, at depths of 70 to The small scales of the Atlantic 210 m. ln the spring, the more local mackerel give the skin a velvety southern population moves inshore texture. As in many fish, the body is towards the American coast to spawn. countershaded, dark above and light The Canadian or northern con- below. The steel-blue upper surface has tingent migrates northward in spring 23 to 33 dark wavy bands extending from the same over-wintering ground. down to the midline. The lower sides The migration route is not well are silvery with a coppery or brassy iri- understood but it appears that the descence. The belly is silvery-white. contingent moves in a broad band This fish has no swim bladder (often covering most of the Scotian Shelf. called air bladder) and thus it must Sorne large adults arrive inshore along swim continuously to avoid sinking. the Nova Scotia coast in mid-May, on Fig. 1 Atlantic mackerel Most mackerel caught in the com- their way to the main spawning ground mercial fishery are from 25 to 40 cm in the Gulf of St. Lawrence. Immature in length, and weigh between 200 and fish apparently migrate later, and 700 g. many may spend the summer along the Atlantic coast of Nova Scotia. Adults spawning in the Gulf of St. *The large, fast-swimming tunas were previously classified in the same family, but now forma distinct but Lawrence usually remain there or move closely-related family, the Thunnidae. to the areas around Newfoundland 3

(including the east coast) to feed, most likely that females release the before migrating south in October for majority of their eggs at one time, the winter. The timing and the exact rather than releasing a series of smaller destination of these migrations are batches throughout the season. The probably controlled by the duration of fecundity of most spawning females is daylight and the water temperature. In quite high, between 200,000 and years when the water is warmer, mack- 500,000 eggs. erel are abundant off the south and Once released into the water, these east coasts of Newfoundland from eggs suffer an estimated mortality of August to October. 50 per cent per day. Larval mortality is Before the construction of the also very high. The specific causes of causeway across Canso Strait in 1954, egg and larval mortality are not well some mackerel used that route to known. Of course, many groundfish migrate into the Gulf of St. Lawrence. and pelagic fish, including mackerel However, the mackerel population bas and herring, feed on these drifting flourished since then, and this disrup- mackerel eggs and larvae, as well as on tion of part of the migratory path the eggs and larvae of many other apparently bas not affected the total species. lt is also possible that larger stock. larvae may prey upon smaller larvae, especially at high densities. Eggs and Life history larvae are also very sensitive to temp- The northern population of Atlantic erature changes. mackerel contains approximately equal lt is estimated that about 20 per cent numbers of males and females. Sorne of adult mackerel die each year from fish are mature at two years of age at a causes other than fishing. Sudden length of about 30 cm. Most are ma- drops in temperature may kill even ture by four years of age. adult mackerel. Mass mortalities have Eggs are found only in waters over been observed along the northeast MAC KEREL l0°C. In the main spawning area in the coast of Newfoundland in the late fall. southwestern Gulf of St. Lawrence, the Mackerel are preyed upon by large sea greatest numbers are found between animais such as whales, seals, tunas, the Magdalen Islands and the Gaspé and sharks, and also by sea birds, such Peninsula. Spawning takes place in as gannets. Cod and squid also feed CANADA open waters and near the surface in late upon small mackerel. June and early July, with a peak activi- Fishing mortality may take place as ty at about 12°C. The eggs and sperm early as one year of age, depending are released into surface waters and upon the selectivity of the gear used. In must rely on normal water movement recent years, the rate of fishing mortal- and turbulence to bring them in con- ity bas varied greatly. When interna- tact to allow fertilization of the eggs . tional fleets were heavily exploiting the The fertilized eggs then take about over-wintering populations in the early seven days to develop and hatch. lt is '70s, it is estimated that 44 per cent of mackerel four years of age and over were captured each year. ln 1979, with no major international fishery, the rate was about 14 per cent. Fig. 2 General d"stribution of A tlantic Mackerel feed on plankton (small mackerel in the Northwest Atlantic. crustaceans, fish eggs, and larvae) and on small fish (notably capelin, juvenile herring, and mackerel). They engage in both "particulate" feeding (the active pursuit of larger plankton and fish) and "filter" feeding (the gill rakers filter small food items from the water). Heaviest feeding takes place in the spring, when food availability may affect the distribution of fish, espe- cially off Nova Scotia. 4

In the Gulf of St. Lawrence the high Mackerel catches increased dram- summer water temperature and the atically during the late 1960s due to the accompanying high food productivity development of a fishery on the over- permit a rapid first season growth to wintering stocks, carried out by large about 20 cm before the fall migration. freezer and factory trawlers, mostly The total length after one full year is from the USSR, Poland, East Ger- between 22 and 29 cm. Second-year many, and Bulgaria. This fishery was growth is slower, and two-year-olds are rendered possible by the exceptional about 30 cm long by the end of the abundance of the 1959 and 1967 year- year. Few fish survive to 40 cm or classes of young mackerel. Fear of longer, corresponding to an age of at over-fishing prompted the Interna- least 10 years. tional Commission for the Northwest Atlantic Fisheries (ICNAF) to impose The fishery an initial TAC limit in 1973 of Northwest Atlantic mackerel have 450,000 t. The TAC was gradually been harvested since the l 7th century. lowered as scientists gained a better Landings have been extremely vari- understanding of the dynamics of the able. For example, the total catch was stocks. With a TAC of 105,000 t in 8,000 metric tons (t) in 1962, but it had 1977 and 1978, total catches were only risen to 420,000 tin 1973. Catches have 78,000 and 28,000 t respectively. The varied because of changing market low catches in those two years relative conditions, new technological develop- to the TAC are largely due to the in- ments, variations in the abundance of ability of the American fishermen to mackerel and the development of the take their share of the allocations, as foreign offshore fishery. Since 1973, well as the absence of the large trawler the fishery management policies of the distant water fleet in 1978. These low Canadian and American governments catch levels did not reflect a very low have had a major impact on annual stock abundance and for 1979 the catches. Management is achieved scientific analyses indicated that through the licensing of vessels, and 150,000 t could be safely taken. How- the setting of a Total Allowable Catch ever, market conditions were extremely (TAC) and national allocations. limiting, and the only major effort was During the 19th century the by Canadian inshore fishermen, who Americans developed a large market accounted for more than 90 per cent of for salted mackerel. Using hook and the 33 ,000 t catch. Fig. 3 Empty ing the net line gear, they followed the northern In recent years, the development of population as far north as the Gulf of new markets for canned mackerel and St. Lawrence. During the 1870s the the direct sale of mackerel from American fishery converted to purse Canadian fishermen to foreign buyers Fig. 4 Nominal catches of A tlantic mackerel seines and was successfully conducted have encouraged the expansion of the from the Northwest Atlantic (NAFO doser to home. The total catch reached inshore fishery. The Canadian govern- Subareas 3-6) . 105,700 t in 1884, but had fallen to ment has purchased large quantities of 5,700 t by 1910. canned mackerel from some processors

Mackerel During the early years of the 20th for foreign aid programs. The Depart- NAFO Subareas 3,4,5, +6 century, vessels converted from sail to ment of Fisheries and Oceans in con- motor power, and a fresh-fish market junction with fishermen's organiza- developed. Canadian landings exceed- tions have contracted to permit ed 18,000 t by the late 1930s, but subse- "over-the-side sales" of mackerel from quently declined to a low of 5,459 t in Canadian inshore boats directly to 1961. American landings dropped rap- foreign factory freezer vessels. idly after the Second World War due to A large part of the increase in the Jack of market development. Since landings is also due to the un- the mid-1950s they have fluctuated precedented expansion of the fishery between 500 and 4,000 t, lower than on the east coast of Newfoundland, any year since 1815. However Ameri- which now accounts for 50 per cent of can sports-fishery landings have been all Canadian landings. This fishery, '70 much higher, exceeding 33,000 t in which traditionally has caught about YEARS 1969. 1,000 ta year, caught 15,000 tin 1979. This has been made possible by the new Unfortunately, our biological know- marketing opportunities, as well as by ledge of the Atlantic mackerel is still an increased abundance of mackerel in quite limited. Information important Newfoundland waters. Higher than to the assessment, such as the rate of average autumn surface water temper- non-fishing mortality, or the abun- atures in the Newfoundland area are dance of juveniles, can be only crudely possibly responsible for this major estimated at the present time. redistribution of mackerel. Market Another long-term research problem expansion has also permitted increases is posed by our inability to specify in landings in the traditional inshore what number of spawning fish is neces- mackerel fisheries of eastern New sary to provide a given production of Brunswick, Prince Edward Island, young. This is probably because the Cape Breton Island, and the Atlantic number of juveniles is also influenced coast of Nova Scotia. by the temperature of the water for The Canadian mackerel fishery is an eggs and larvae, competition among inshore small-boat fishery. On the larvae, and predation by larger fish on eastern shore of Newfoundland, the younger stages. main gear is purse seines and bar Still another management-related seines. In the Gulf of St. Lawrence, gill biological problem is the difficulty in nets have become the dominant gear in determining when and where the mack- recent years, although small purse erel are going to show up. This is espe- seines accounted for most of the cially important in the case of an landings throughout the l 970s. Purse inshore fishery. In recent years fish seines are the major gear on Prince have been exceptionally abundant off Edward Island, whereas in New Bruns- eastern Newfoundland. This develop- wick gill nets are the primary gear. On ment was not predicted and more Cape Breton Island, mackerel are information about mackerel ecology is Fig. 5 Hauling in the seine caught by handlines, trap weirs, and necessary before scientists will be able gill nets. The fishery along the outer to predict with confidence this kind of coast of Nova Scotia is dominated by local abundance trend. trap weirs, and gill nets . Most mackerel One of the most critical pieces of fishermen also fish other species, nota- information in the scientists' assess- bly lobster, herring, and groundfish. ment of a fish stock is the estimation of The economic importance of the the population. In the case of the mackerel fishery has increased greatly Atlantic mackerel there are two main in recent years. The total landed value approaches to this problem. The first climbed from $2 million in 1976 to technique, used mainly by American more than $6 million in 1979. The scientists, involves the use of an index mackerel fishery plays an important of stock size. Each spring and fall, role in the economy of the multispecies American research vessels conduct a inshore fishery. standard survey with a bottom trawl. Mackerel for human consumption is These cruises are planned principally to sold whole or canned. Some mackerel survey the abundance of juvenile her- is also sold cured or as frozen fillets. It ring, but mackerel are also caught. The is also a preferred bait for the snow year-to-year variation in the numbers crab and tuna fisheries. An unknown of mackerel caught per tow provides an quantity of mackerel is reduced to index of variations in the abundance of fishmeal and oil. the population. This index can be confirmed by comparison with another Research and resource index derived from the catch per day of management the American commercial fishing fleet. Fisheries research scientists are It is, of course, difficult to estimate the essential members of the fisheries numbers of "pre-recruits" - juvenile management team. Regular scientific fish not normally caught in commercial "assessments" of exploited fish gear, who will form the mainstay of the populations provide the biological fishery two or three years later. information which is necessary to the A second technique for estimating development of a management plan. the abundance of the mackerel QL 626 U5313 no.17 c.2 Ahrens, M.A. 6 Atlantic mackerel

257939 12064603 c.2 population has been introduced by least three related problems which Underwater World factsheets are Canadian scientists. ln this case, an hinder the development of the Cana- brief illustrated accounts of fisheries annual research survey determines the dian mackerel fishery. Firstly, existing resources and marine phenomena pre- abundance of mackerel eggs in the mackerel markets are concentrated in pared for public information and surface waters of the Gulf of St. countries that do not offer a sufficient education. They describe the life Lawrence during the spawning season. price to permit profitable fishing and history, geographic distribution, This information, combined with pre- processing in Canada. Secondly, mack- utilization and population status of cise knowledge of the fecundity of indi- erel has a high oil content and perishes fish, shellfish and other living marine vidual fish, should permit the estima- rapidly. Both fishermen and processors resources, and/ or the nature, origin tion of the total number of spawners in risk the Joss of their product unless and impact of marine processes and the Gulf. The stock abundance then they use adequate cooling facilities. phenomena. may be estimated by observing the Tanks with slush ice are recommended relative numbers of spawning and non- for boats and small plants, while Others in this series: spawning fish in commercial catches. refrigerated seawater systems are Arnerican Lobster The northern contingent of the recommended for larger installations. Arnerican Oyster Atlantic mackerel has a number of Thirdly, there may be an oversupply of Arnerican Plaice ecological relationships with other fish mackerel relative to the existing world Atlantic Groundfish stocks, so it cannot be managed in market. A major component of this Atlantic Herring isolation. We know, for instance, that problem is the Jack of market develop- Altantic "Pelagic" Fish the northern and southern mackerel ment in North America. If the Cana- Atlantic Shellfish contingents intermingle during the dian mackerel fishery is to achieve its Atlantic Snow Crab winter. But no precise information is full potential, then considerable work Capelin Harp Sea! available about the degree of inter- must be done to promote mackerel Irish Moss mixing or competition and thus it is products in the Canadian and Ameri- Red Hake difficult to predict the effect of the can markets. Red Tides abundance of the northern spawning Roundnose Grenadier group on the southern group or vice- Further Reading Sea Scallop versa. Spiny Dogfish Dingle, J.R. 1976. Technology of The northern contingent has impor- Witch Flounder mackerel fishery: bibliography and tant relationships of competition and survey of literature. Miscellaneous predation with other species of fish. As Aussi disponible en français special publication DSS. well, mackerel feed on capelin in the 30. Leim, A.H ., W.B. Scott. 1972. Fishes Gulf of St. Lawrence and off New- of the A tlantic coast of Canada. Bull. foundland. Both of these species are No. 155. Fisheries Research Board fished commercially. Further, in the of Canada. (Atlantic mackerel Gulf of St. Lawrence, mackerel have a p. 284-87). number of relationships with cod and Pinhorn, A.T. 1976. Living marine herring throughout their life cycle. The resources of Newfoundland- fishery on any one of these fish stocks Labrador: status and potential. Fish will obviously have some effect on the Res Bd Can. Bull. No. 194 (p. 30-31). other related stocks. Resource prospects for Canada's Atlan- The details of these interactions, and tic fisheries. 1981 -87. Dept. Fish and thus the consequences of fishing are Oceans. (p. 26-27). not yet sufficiently well understood Scarratt, D.J. ed. 1982. Canadian to allow their use in the scientific Atlantic offshore fishery atlas. management of the three major fish- (p. 83). Cdn Special Publication of eries involved. At present, manage- Fisheries and Aquatic Sciences 47. ment proceeds on a stock-by-stock Dept. Fish and Oceans. basis and more research is needed to The management and utilization of enable managers to make decisions in Atlantic herring and mackerel in the the best long-term interest of ail the Published By: 1980s. Dept. Fisheries and Oceans. Communications Branch interacting fisheries. Department of Fisheries and Oceans Management of the Atlantic macker- Ottawa, Ontario el is still in a development stage. KIA 0E6 One of the difficulties in developing a DF0/ 584 UW / 017E comprehensive management plan is the © Minsiter of Supply and Services Canada 1982 uncertainty about markets and prob- Cat No. Fs 41 -33/17 - 1982E lems in product quality. There are at ISBN 0-662-12204-6