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Pacific herring, Biological Station, Nanaimo, British Columbia.

The following 1994 document represents a collaborative effort between Fisheries and Oceans (DFO) and Environment Canada (DOE). It is part of the DOE State of the Environment Reporting Program where it is available in a slightly different format. The document presented here is equivalent to the hardcopy version available from DOE.

The indicators in this bulletin are part of a national set of environmental indicators designed to provide a profile of the state of Canada's environment and measure progress towards sustainable development.

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Background: Pacific Herring

Over the years, serious concerns have been raised about the intensity of fishing on Canada's coasts. Populations of various fish species have been fluctuating significantly as a result of harvesting pressure and natural variations. Current knowledge and understanding of mechanisms that contribute to biological capacity and population fluctuations of different fish stocks are incomplete. A sustainable development strategy would attempt to balance the various demands for fish species, taking into account natural ecosystem and species population fluxes to assure future productivity of fish resources and ecological diversity.

The Pacific herring fish stocks of Canada's west coast are a marine resource that is highly valued internationally, provides employment for thousands of Canadians and a way of life for numerous coastal communities, and contributes millions of dollars to Canada's economy. Pacific herring is, itself, a regional indicator of marine resource sustainability carrying national significance.

  • A small silver-coloured fish, Pacific herring are the most abundant fish species in Canada's Pacific coastal waters. About 500 linear km of British Columbia's coastline turn milky-white every March and April, as a result of the herring's release of countless sperm around the eggs (roe) spawned on algal beds.
  • Central in the marine food web, Pacific herring are a key fish prey contributing 30 to 70% to the summer diets of Chinook salmon, Pacific cod, lingcod, and harbour seals in southern B.C. waters. Herring eggs constitute an important part of the diets of migrating seabirds and gray whales, and invertebrates.
  • The wholesale market value of herring roe in 1993 was $180 million, second only to Sockeye salmon. The herring fishery in recent years has employed up to 6 000 people from February through June, with almost 1 200 vessels participating.
  • Pacific herring are important to Native peoples, other Canadians, and Japanese as traditional food, delicacies, fishing bait, and food for zoos and aquariums. Herring roe called kazunoko, a traditional Japanese delicacy, sells for $120 to $150 per kilogram in Japan.
  • Pacific herring spawn in coastal areas, requiring abundant algal beds and uncontaminated waters. A growing concern is a threat by coastal development to the spawning habitat of Pacific herring.

The status and trends of Pacific herring stocks are tracked by key representative indicators of human activities (commercial catch), stock condition (spawning biomass), and economic effects (landed value). As adequate data become available for other indicators, other components of this cycle will be described in bulletin updates.

circle diagram

INDICATOR: ABUNDANCE (SPAWNING BIOMASS) OF PACIFIC HERRING STOCKS

West Coast Vancouver Island

  • As of 1993, the stock was considered an average condition, having rebuilt rapidly to a spawning biomass of 26 000 tonnes after the closure in 1967.
  • A period of warm ocean conditions resulted in poor survival of young herring in the late 1970s and a subsequent large decline of spawning fish in the early 1980s (see below).

Strait of Georgia

  • The stock is considered in good condition; the spawning biomass was at a record high level of 80 000 tonnes in 1993. This is a result of successive strong year-classes in 1983, 1985, 1987, and 1989. In the early 1980s, the spawning biomass was again relatively low.

Central Coast

  • This stock is considered in good condition. Two very strong year-classes in 1985 and 1989 contributed to the record high spawning biomass of 50 000 tonnes in 1993.
  • Since the 1960s, this stock has steadily increased, although there have been several temporary declines in biomass.

Prince Rupert

  • The 1993 spawning biomass of about 20 000 tonnes is considered an average condition for this stock.
  • Survival of young herring was average or below average in the 1970s, and spawning biomass showed very slow rebuilding, in spite of limited fishing pressure. Strong year-classes in 1977, 1981, 1985, and 1986 have contributed to more rapid biomass increases through the 1980s and 1990s.

Haida Gwaii

  • In 1993, this stock was in poor condition, with a spawning biomass of only 11 000 tonnes.
  • From the 1960s to 1970s, spawning biomass went from record low to record high levels. Survival of young herring has been generally poor in the 1980s and 1990s, except for strong year-classes in 1977 and 1985. This explains the peak biomass in the early 1980s.

INDICATOR: COMMERCIAL CATCH OF PACIFIC HERRING

Commercial catch of all Pacific herring stocks (1951-1993), in relation to spawning biomass

  • Until the late 1960s, herring were harvested and processed (reduced) into low value products, such as fish meal and oil. This "reduction" fishery caught very large quantities of herring, up to 250 000 tonnes in one year, greatly exceeding the estimated biomass left alive to spawn.
  • By 1965, nearly all major herring stocks had been discovered, and most of the older spawning fish had been removed from the populations by overfishing. This removal coincided with some naturally weak year-classes, drastically reducing the herring left to spawn to only 15 000 tonnes coast-wide.
  • The commercial fishery could not be sustained and collapsed. In 1967, the federal government stopped all B.C. commercial herring fishing for four years, except traditional food and bait fisheries.
  • Many fish stocks can be irreversibly damaged by low spawning biomass over a series of years. Fortunately, herring belong to a group of fish species which may recover dramatically from a reduced population size and has rebuilt to 100 000 to 200 000 tonnes.
  • By 1972, a new fishery began to harvest herring for its roe. This roe fishery catches fewer fish than was taken in the "reduction" fishery, averaging 35 000 tonnes per year.
  • Native peoples are also active participants in the food and commercial roe fishery. In 1991, they owned about one-quarter of the herring roe fleet vessels and almost 75% of the licenses to harvest roe spawned on kelp.
  • The size and use of the commercial catch of Pacific herring have changed dramatically over the past four decades.
  • The five Pacific herring stocks are harvested and managed solely by Canada: no other countries fish these stocks.
  • Since 1983, catches have not been permitted to exceed 20% of each stock's spawning biomass, as forecasted annually. The fishery can be closed should stock abundance fall to low levels. The general goal is to produce a low volume of a high-quality product, judged to be both economically profitable and ecologically sustainable.

INDICATOR: ECONOMIC VALUE OF PACIFIC HERRING

Landed value of commercial catch of Pacific herring (1935 - 1993)

Since 1982, the value has generally been well above $40 million although the current "roe" fishery harvests only about one-tenth the herring caught during the "reduction" fishery of the 1960s. The landed value of the commercial catch has fluctuated widely over the past five decades reaching an historic high in 1979 of about $150 million. Declining stocks and catches reduced the landed value in the early 1980s. Since then, stable catches, increases in product quality, and a favourable exchange rate with Japan has resulted in increases in the landed value of the roe fishery. Canada is the major exporter of roe to Japan, the world's largest and only market, because B.C.'s herring roe is of such high quality. The carcasses of the herring left over after roe removal are reduced into fertilizer and animal feed. In 1991, on average, herring contributed $214 500 to gross income of a herring boat, while other species, mainly salmon, accounted for $146 500 per boat. The roe fishery has extensive spin-offs for B.C. fishery workers and processors, resulting in thousands of additional jobs in the labour-intensive processing of the roe and other herring products.

Chronology of significant events

The following events, decisions, and actions illustrate the growing intention of government and industry to manage the Pacific herring resource in a sustainable manner.

Year Event, decision, or action
1877 First recorded commercial catch
1936 Establishment of catch quotas on southern coast herring stocks
1941 Establishment of catch quotas on north coast herring stocks
1967 Reduction fishery closed coastwide to conserve dwindling stocks
1971 Beginning of experimental roe fishery
1972 Beginning of commercial roe fishery
Introduction of optimal escapement policy for fishery management
1974 Limited entry of fishers introduced to manage the fishery
1975 Beginning of commercial production of herring roe spawned on kelp
1983 Introduction of fixed 20% harvest rate policy and area licensing to manage fishery
1985 West Coast Vancouver Island roe fishery closed for one year due to low biomass caused by natural factors
1986 West Coast Vancouver Island and Strait of Georgia roe fisheries closed for one year due to low biomass caused by natural factors
1988 Haida Gwaii roe fishery closed for one year due to low biomass caused by natural factors
1994 Haida Gwaii roe fishery closed for one year to low biomass caused by natural factors

The biology and status of Pacific herring stocks

Pacific herring stocks are named after their geographical spawning areas - West Coast Vancouver Island, Strait of Georgia, Central Coast, Prince Rupert, and Haida Gwaii.

Pacific herring generally spawn annually beginning at age three. Survival and abundance of a herring year-class (herring born in the same year) vary considerably owing to complex ocean factors, including predators. These, in turn, primarily determine whether the biomass of spawning herring increases or decreases. One or more successive strong year-classes produce an increase in the spawning biomass after three years.

In the mid-1960s, the abundance of all stocks underwent a drastic crash, as clearly shown by the estimated biomass of spawning herring. The crash was caused by a combination of intense harvests and unfavorable ocean conditions coastwide.

Fishing was stopped in 1967, environmental conditions improved, and the spawning biomass of all stocks rebuilt quickly in the 1970s. In 1993, most stocks were in good condition; their abundance equalled or exceeded historic levels.

The current conservative harvesting rate lessens the combined effects of environmental factors and commercial fishing on herring abundance. This, in turn, enhances the long-term sustainability of the Pacific herring resource.

Threats to the herring's habitat

Pollution and other coastal human stresses, particularly near coves, inlets, and estuaries, can destroy, contaminate or alter algal beds used by spawning herring thereby affecting herring survival and growth. In British Columbia, the evidence for such local impacts on a herring stock and its spawning grounds is, in part, circumstantial, because the herring return to spawn in the same general, but not specific, location each year.

Map of major herring spawning areas

Some significant losses of herring spawning habitat have been recorded within the Strait of Georgia, a region of the province's greatest human settlement, industrial development, and marine transport. For example, herring spawned repeatedly in Nanaimo Harbour, nearby Newcastle Channel and Ladysmith Harbour until 1950, but not since. The Nanaimo Harbour foreshore has been completely altered by urban development, and Ladysmith Harbour has become an important site for log storage over the last several decades. Herring have not returned to spawn in Pender Habour, 70 km north of Vancouver, since 1977; this locale has experienced waterfront residential growth over the past two decades.

Fisheries and Oceans Canada scientists currently are assessing this and other evidence of herring habitat losses along the B.C. coast. Their analyses may show trends that can be reported as new environmental indicators in bulletin updates. See the most recent edition of the Herring Geographical Bulletin of British Columbia.

The influence of natural factors: Ocean climate, predators and the the West Coast of Vancouver Island herring stock

Survival and growth of Pacific herring are sensitive to natural fluctuations in ocean climate and ecology. It is necessary to understand this complex interplay to resolve the added effects from pollution and fishing; thereby sustaining herring stocks into the future.

One of the more important natural factors is ocean temperature, which influences herring survival and growth directly, and also indirectly by altering the abundance of herring predators, principally Pacific hake. Waters off the West Coast Vancouver Island undergo alternate warm and cool periods (Figure 1). Warm periods since 1976 have been intensified by strong El Nio events.

Figure 1. Sea surface temperature off the west coast of Vancouver Island

During these warm periods, survival and growth of young herring are weak due to the abundance of Pacific hake and the high water temperature, frequently associated with El Nios. Strong El Nio events further reduce young herring survival because large numbers of Pacific mackerel migrate north into B.C. waters and feed on herring, salmon, and other species during the summer. The result is a decline in spawning biomass of the West Coast Vancouver Island herring stock because fewer young herring survive to join the spawning stock. Conversely, survival and growth are relatively strong when the summer biomass of hake is low and the annual water temperature is cool, in the range of 10C.

Natural predators, rather than the fishery catch, account for most herring mortality. The eight most abundant predatory fish harvested off the West Coast Vancouver Island devour an estimated combined average of 45 000 tonnes of herring each year. This is six times greater than the average annual herring fisheries harvest of this stock (Figure 2).

Figure 2. Predation and fishery harvest of West Coast Vancouver Island herring stock

Acknowledgements:

This bulletin was prepared jointly by the federal Departments of Environment and Fisheries and Oceans.

Data and advice provided by the following agencies are gratefully acknowledged:

  • Pacific Biological Station;
  • Institute of Ocean Sciences;
  • Economics Branch;

British Columbia Ministry of Agriculture, Fisheries and Food.

For further information or to obtain copies of this Indicator Bulletin and Technical Supplement, please contact:

State of the Environment Directorate
Environment Canada
Ottawa, Ontario K1A 0H3

or

Jake Schweigert
Fisheries and Oceans Canada
Pacific Biological Station,
Nanaimo, B.C. V9T 6N7.