- Atlantic Herring
QL 626 U52 No 16 1984 2 Underwater World
lthough Canadians have been eating The Atlantic herring has a stream- A Atlantic herring canned as sardines lined, elongated body, much deeper since the 1870s, many are not aware that than it is thick, with an iridescent steel- Atlantic Herring they are not the true sardines of the blue or greenish-blue back and silvery genus Sardinops, which are not found sides and belly that provide excellent in Canada. camouflage in the open sea. It has a In 1953, a reduction plant fortrans- deeply-forked tail, large loosely- forming herring into fishmeal and oil attached scales and a single dorsal fin on was opened in the Magdalen Islands, the back. and other plants followed in New Bruns- wick, Newfoundland and Nova Scotia. Life History By 1968, most Canadian herring catches In the northeast Atlantic, the Atlantic were being reduced to low-priced fish herring ranges from northern Labrador meal or oil. However, with the failure and Greenland to North Carolina. On of several major herring fisheries around the other side of the Atlantic, herring is the world in the early l 970s, the demand found from Spitzbergen, north of for food herring increased. Prices to Norway, to Gibraltar, at the entrance to fishermen rose from an average of one the Mediterranean. cent a pound in 1%9 to 12 cents a pound Along the Canadian Atlantic coast, in 1979. spawning may occur in any month be- Now herring is seldom used for fish tween April and October, but it is con- meal production. Most of it is exported centrated in May and September. Most as frozen fillets, sardines, pickled and evidence shows that spring and fall cured fillets, and pickled and cured spawners are biologically independent whole-dressed herring. Whole herring is stock groups. also sold fresh or frozen and is used as It is not clear what factors contrai the lobster bait. The preparation of roe for timing and locality of spawning. How- the Japanese market is a lucrative activ- ever, herring eggs adhere to abjects on ity which bas probably not yet attained the seabed, such as rocks, grave! and its full potential in Atlantic Canada. algae. Less stable surfaces do not pro- vide the necessary conditions for the Description maintenance of a spawning bed. Sorne The Atlantic herring (Clupea haren- fishermen claim that the timing of g us) is one of the best known open sea spawning is precisely related to the lunar fish on Canada's east coast. It is a mem- cycle. This idea bas never been fully ber of the Clupeidae family found in evaluated by scientists and the existing many parts of the world, including some evidence is contradictory. ln the south- species living in inland lakes. Arnong west Gulf of St. Lawrence, the peak of Clupeidae on Canada's east coast are spring spawning is apparently related to the blueback herring, the gaspareau or the water temperature. However, there alweife, the shad and the menhaden. is also evidence of a fixed number of waves of spring spawners regulated by factors other than water temperature. Fall spawners reproduce at very differ- ent temperatures than spring spawners in the same area. 146535
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lmproving knowledge of the subse- quent survival and growth of larvae and juveniles is a frontier of biological researcb. After they have absorbed the yolk sac retained from the egg stage, young larvae risk starvation if their hatching is not followed by a period of adequate food production. They also Quebec may be dispersed if currents are not suitable. Predation by pelagic fish such as mackerel and herring may be a major cause of larval mortality. The larvae of some stocks bave been shown to stay very close to the spawning bed where they were hatched. This is a result of the formation of tidally- induced retention areas, which prevent larvae from being dispersed by water currents. When these larvae metamor- phose into juvenile herring, the resulting schools are composed of fish from the same spawning site. Since the members of a school stay together, this results in 30 fathom hne the maintenance of separate stocks, even ------100 fathom line though mixing with other stocks may occur during feeding or overwintering. The length of time it takes for larvae to metamorphose into juvenile herring is related to the water temperature and the availability of food. Larvae hatched in the early summer will become ju- During spawning, eggs and rnilt veniles that same year, whereas fall (sperm cells of male fish with tbeir rnilky hatched larvae will not metamorphose fluid) are released into the water by until the following spring or summer. herring in scbools. Eggs remain attached The length and age at sexual maturity to the seabed until hatching, which takes have varied in Canadian populations of about 30 days at 5°C, a typical spring the Atlantic herring. As a rule, the spawning temperature, and only 10 days youngest mature herring are three years at 15°C, typical of Gulf of St. Lawrence old, and almost all are mature by age fall spawning temperatures. Fall- five . But it appears that to a certain spawned eggs off soutbwest Nova Scotia extent they will become sexually mature develop at about 10°C. at a younger age as populations dirninish Before 1970, wben most populations under intensive fishing. In 1978 in the were more abundant tban they are now, the water would turn white over inshore spawning beds due to the release of milt from male spawners. Storms would carry waves of eggs onto the beaches, where in some localities tbey were shov- elled into wagons and used to fertilize the fields. Eggs are also eaten by groundfisb like cod and haddock, and various flounders.
ÇJL 626 U52 No 16 1984 4 Unde rwater Wo rld
Gulf of St. Lawrence, three-year-olds Herring are the prey of a number of were about 25 cm long, while five-year- open-sea predators, such as cod, tuna, olds were 30 cm in length. Growth rates sharks, dogfish, squid, sea birds, seals vary between and within stocks over and whales. Herring may also fall vic- time. These variations are not fully tim to disease. Between 1954 and 1956, understood, but are certainly influenced many herring in the Gulf of St. by the water temperature and popula- Lawrence
these same coasts. They again mix in the Fishery and Stock Trends fall, mainly in Chaleur Bay, in prepar- Prior to the mid l 960s, in most areas ation for the migration to overwintering of Atlantic Canada, herring were caught areas. ln the late l960s, when these by small inshore boats using gillnets or stocks were much more abundant than traps, or in weirs. Catches - made they now are, most adults would rnigrate alrnost exclusively during spawning runs to the deep fjords of southwest New- - were limited more by markets than foundland, where they were heavily by abundance of fish. However, Bay of fished during the winter. Fishing would Fundy weirs have always caught juve- again occur in the spring when these nile fish during their summer feeding. same fish would rnigrate back into the Purse seines used to be limited to a fleet fig. 2. Gillnet Gulf along the edge of the Laurentian of small boats in the Bay of Fundy. And Channel. Herring is no longer found in in the Magdalen Islands, herring were abundance in either of these areas. traditionally caught in floating trap nets. However, part of the southern Gulf Between 1965 and l 972, catches adult herring group is known to over- increased rapidly due to the introduction winter in the Sydney Bight off Cape of a fleet of large purse seiners. But total Breton Island. Here they mix with fish landings have declined considerably from the southwest Nova Scotia stocks from the record levels attained in the as well as local spawning populations. early l 970s, and today' s herring fleets Juveniles do not undertake such exten- are underutilized due to a Jack of sive migrations. sufficient fish to catch. Each of the larger bays around New- The most dramatic fluctuations in foundland supports a local herring landings and stock size have occurred in population. These fish do not migrate the southern Gulf of St. Lawrence fish- as far as the larger Bay of Fundy and eries. In 1965, purse seiners began fish- Gulf of St. Lawrence groups. ing there and in southwest Newfound- Georges Bank was formerly the Iand, where the adult stock used to over- spawning ground for a large herring winter. The subsequent high landings population. However, a large interna- were made possible by the abundant tional fishery developed there in the 1958, 1959, 1962 and 1963 year classes; l 960s with the USSR as the most active the catch increased from 39,000 participant. Overfishing eventually led tonnes (t) in l 964 to nearly 300,000 tin to the collapse of this fishery, and sur- 1970. But the winter fishery collapsed in veys in the area have found very few the early '70s, and landings reached a larvae sin ce l 977. low of 37 ,000 t in 1974. Our knowledge of the stock structure Most of the herring caught in the of herring is based upon several sources southern Gulf fishery was caught by of information. Tagging studies are a purse seiners from the Iate '60s until traditional method. Meristic studies 1980. As stocks declined, some formerly compare the counts of some body parts, important spawning sites in Chaleur Bay especially vertebrae, gill rakers and fin and Northumberland Strait became rays. These counts are different between much Jess productive for the gillnet fish- fish from some stocks. Biochemical eries concentrated there. The Magdalen studies have recently shown that there Islands trap fishery has virtually disap- are clear genetic differences between peared. Since 1980, overall Total Allow- fall-spawning and spring-spawning able Catches (TAC) have been reduced herring. by fishery managers and only 20 per cent of the total is now allocated to seiners. In Newfoundland the traditional fish- eries took place in Fortune Bay and in the area of the Port-au-Port Peninsula. Gill nets were the traditional gear, but purse seines were introduced as early as the l 930s. The first major purse seine fishery on local Newfoundland stocks began in 1966 north of Cape St. Gregory on the west coast, and activity spread to 6 Underwater World
St. George's Bay in 1975. ln recent niles during the summer and fall, while years, catches in western Newfoundland the gillnetters concentrate on the adult have been shared between seiners and fall spawning run. The total catch for gillnetters. The total catch reached a the southwest Nova Scotia stock, ex- record 19,000 t in 1980, but poor cluding the New Brunswick Bay of recruitment of young fish had forced a Fundy fishery for juveniles, reached a decline to half this level by 1982. peak ofnearly 190,000 tin 1970. About The 1968 year class of herring was 85 ,000 t per year were caught in 1981 abundant around the Newfoundland and 1982. coast, permitting the development of a The New Brunswick Bay of Fundy mobile purse seine and ringnet fleet fishery, which exploits herring schools during the early l 970s. On the east from several neighboring stocks, is the coast, landings reached a record home of Canada's oldest purse seine 26,000 tin 1979, when the inshore fish- fishery and the sardine canning industry. ery caught 70 per cent of the herring. Weirs are the main fishing gear, supple- Recruitment was very poor however, mented by shut-off seines and purse and the stocks had dwindled to such a seines. Landings reached 75,000 t in low Jevel that fishing was curtailed in 1968 and have varied considerably since 1983. Smaller fisheries in Placentia Bay, then. The 1982 catch was about St. Mary's Bay and Fortune Bay were 25,000 t. closed for the same reason in 1982. George's Bank was formerly the In Nova Scotia, inshore fishermen in spawning ground for a large herring Sidney Bight and Chedabucto Bay fish population, and an international fishery local spawning runs of herring. Purse developed in the l 960s with the seiners in these areas fish overwintering U .S.S.R. as the most active participant. herring. The winter seine fishery in In 1968, Canadian vessels caught Sydney Bight began in 1968 and reached 13,674 t out of a total catch of a peak of 17 ,547 t in 1973, only to 373,344 t. Overfishing eventually led to decline to less than 4,000 t per year by the collapse of this fishery, and surveys the early l 980s. Catches are a mixture in the area have found very few larvae of overwintering herring from southwest since then. Nova Scotia, the Gulf of St. Lawrence, Canada's participation in the herring and local Cape Breton stocks. The peak fishery in the Gulf of Maine has decreas- catch from the winter fishery off ed considerably in recent years due to Chedabucto Bay was in the order of the poor state of the adult stock. Since 50,000 t in the early 1970s. More 1977, when both Canada and the Uni- recently catches have varied between ted States extended their jurisdiction 10,000 and 20,000 t per year. The over fisheries to 200 miles, Canada has Chedabucto Bay fishery has been not had a fishery in the Gulf of Maine. shown, by tagging studies, to be closely associated with the Southwest Nova Research and Management Scotia stock and has been managed in Modern herring fisheries are very fig. 3. A purse seiner conjunction with the southwest Nova difficult to manage. Purse seiners are Scotia fishery since 1974. The TAC for capable of capturing entire schools of the fishery off Chedabucto Bay is deter- fish in a few hours. Gillnets may become mined according to the management so heavily concentrated over spawning plan for the southwest Nova Scotia beds that most of the herring in a run fishery. are captured before having a chance to A purse seine fishery for juvenile and reproduce. Overfishing has in fact com- adult herring is carried out off southwest bined with poor recruitment of young Nova Scotia in the early summer and fish to reduce several Canadian Atlan- early fall. A weir fishery catches juve- tic herring stocks to very low levels. Overfishing results in the loss of pro- duction due to growth and in the loss of production of young. Most individuals may spawn only once or twice before being caught. Yet if they were allowed to reproduce more often, they would contribute much more to the production Underwater World 7
of future generations of new recruits. veys are particularly useful to determine The capture of most herring when they the abundance of overwintering herring, are young also prevents fishermen from since stocks are more concentrated then. taking full advantage of the potential Surveys of the numbers of eggs deposit- growth in weight of each fish. However, ed on spawning beds permit back calcu- the maximum possible yield does not lation of the number of parent fish. occur when ail the fish are old and very The most challenging area of research large, since growth rates slow down concerns the understanding of recruit- after a few years, and more fish die ment variability. Acoustic surveys are every year from causes other than fish- being tried to estimate the abundance of ing. It is important to balance off the juveniles. But in order to predict accu- advantages of growth and reproduction rately future variations in recruitment, fig. 4. Gill netting for herring against this continuing mortality when much more information about the rela- deciding what portion of a population tionships between herring and other should be harvested. species and with the environment is Sorne of the largest Canadian herring necessary. Ecological research about fisheries are carried out when fish from these relationships continues. several spawning populations are mixed together for feeding or migration. Further Reading: Under these circumstances, it is impos- Leim, A.H., W.B. Scott. 1972. Fishes sible to predict exactly what portion of of the Atlantic coast of Canada. the TAC will be caught from any one Fisheries Research Board of Canada population. There is a real danger that Bull. No. 155. (Atlantic herring small populations contributing to a large p. 94-97). fishery might accidentally bear much Murphy, G.I., 1977. "Clupeoids" in more than tbeir share. The result can be J .A. Gulland, ed. Fish Population the virtual elimination of these spawning Dynamics, John Wiley and Sons, populations. It may take many years Toronto. before new stocks repopulate the The management and utilization of abandoned spawning sites. Atlantic herring and mackerel in the To help solve management problems, 1980s. Dept. Fisheries and Oceans. scientists must estimate quite accurately Pinhorn, A.T. 1976. Living marine the abundance of fish in a population resources of Newfoundland- at a given time. One very useful guide Labrador: status and potential. Fisb- for some species of fish is the catch rate eries Research Board of Canada. Bull. of commercial fishing vessels . If they No. 194 (p. 27-30). catch more per day tbis year than they Resource prospects for Canada's did last year, tbis suggests fish are more A tlan tic fisheries. 1981-1987. Dept. abundant. But the schooling behaviour Fisheries and Oceans (p. 25-26). of herring complicates this situation. If Scarratt, D.J . ed 1982. Canadian a stock is decreasing in size, high catch Atlantic Offshore Fishery Atlas, rates may still be maintained as long as (p. 81). Canadian Special Publication the schools can be located. A smaller of Fisheries and Aquatic Sciences 47. stock may be distributed over a smaller Dept. Fisheries and Oceans. territory, and experienced fishermen using sophisticated electronic equipment Text: can usually find the fish. Awareness of M.A. Ahrens the complexity of the problem has led Head, Marine Finfish scientists to exercise caution in recent Fisheries Research Branch years in their recommendations for Gulf Region TACs. Moncton, New Brunswick New techniques are being developed to estimate the abundance of herring stocks. Catch rates on spawning fisb- eries are being used to estimate the numbers of reproducers. Acoustic sur- 8 Underwater World
Underwater World factsheets are brief Otbers in this series: illustrated accounts of fisheries re- American Lobster sources and marine phenomena pre- American Oyster pared for public information and American Plaice education. They describe the life history, American Smelt geographic distribution, utilization and Arctic Cod population status of fish, shellfish and Atlantic Groundfish other living marine resources, and/ or Atlantic Herring the nature, origin and impact of marine Atlantic Mackerel processes and phenomena. Atlantic "Pelagic" Fish Atlantic Salmon Atlantic Shellfish Atlantic Snow Crab Capelin Harp Sea! Irish Moss Pacifie Herring Red Hake Red Tides Roundnose Grenadier Selected Freshwater Fish Selected Shrimps of British Columbia Spiny Dogfish Thorny and Smooth Skates Witch Flounder Yellowtail Flounder
Publisbed By : Communications Directorate Department of Fisheries and Oceans Ottawa, Ontario KlA 0E6
DF0/ 1366 UW/16
Minister of Supply and Services Canada 1984 Catalogue Number Fs 41-33/ 16-1984E ISBN 0-662-13108-8
Disponible en français