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COSEWIC assessment and update status report on the Atlantic Cod in Canada

Executive Summary

Atlantic Cod

Gadus Morhua

 

Species information
ClassActinopterygii
OrderGadiformes
FamilyGadidae
Latin binomial     Gadus morhua  Linnaeus 1758
Common namesEnglish -- Atlantic cod
 French -- morue franche
 Inuktitut -- ogac (Nunavut); ovak, ogac (Ungava Bay); uugak, ugak
 (Innu, Labrador) (McAllister et al. 1987)

 

Distribution

Atlantic cod inhabit all waters overlying the continental shelves of the Northwest and the Northeast Atlantic Ocean.  On a global scale, the historical distribution of cod probably differs relatively little from that of its present distribution.  In Canada, Atlantic cod are found contiguously along the east coast from Georges Bank and the Bay of Fundy in the south, northward along the Scotian Shelf, throughout the Gulf of St. Lawrence, around the island of Newfoundland, and finally along the eastern shores of Labrador and Baffin Island, Nunavut.  There are also several landlocked populations of Atlantic cod on Baffin Island.  Outside Canadian waters in the Northwest Atlantic, cod can be found on the northeast and southeast tips of Grand Bank and on Flemish Cap, lying immediately northeast of Grand Bank.

 

Habitat

During the first few weeks of life, cod exist as eggs, and then as larvae, in the upper 50 metres of the ocean.  The primary factors affecting habitat suitability for cod during these early stages of life are probably food availability and temperature.  The most critical habitat characteristics for Atlantic cod may be those required during the juvenile stage when cod have settled to the bottom for the first 1 to 4 years of their lives.  Evidence suggests that a heterogeneous habitat, notably in the form of vertical structures, such as eelgrass, Zostera marina, in near-shore waters, is favoured by juvenile cod because it reduces the risk of predation and may also allow for increased growth.  As adults, the habitat requirements of cod become increasingly diverse.  Indeed, it is not clear that older cod have particular depth or bottom-substrate requirements.  The primary factors affecting the distribution and habitat of older cod are probably temperature and food supply.  From a spawning perspective, it is not known if cod have specific habitat requirements.  Cod spawn in waters ranging from tens to hundreds of metres in depth.  Perhaps the factor most beneficial to the survival of offspring is the presence of physical oceanographic features that would serve to entrain the buoyant eggs and prevent them from being dispersed to waters poorly suited to larval cod, e.g., waters off the continental shelf.  It is highly unlikely that spawning habitat is limiting for Atlantic cod.

 

Biology

The life history of cod varies a great deal throughout the species’ range.  In the relatively warm waters at the southern end of its Canadian range (Georges Bank, off the state of Maine) and in the Bay of Fundy, cod commonly attain maturity at 2 to 3 years of age.  By contrast, cod inhabiting the Northeast Newfoundland Shelf, eastern Labrador, and the Barents Sea typically mature between 5 and 7 years of age.  Size at maturity ranges between 35 and 85 cm in length.  The number of eggs produced by a single female in a single breeding season typically ranges from between 300,000 and 500,000 at maturity to several million eggs for females greater than 75 cm in length.  Egg diameter, which can show a weak, positive association with body size, ranges between 1.25 and 1.75 mm.

Atlantic cod typically spawn over a period of less than three months in water that may vary in depth from tens to hundreds of metres.  Cod are described as batch spawners because of the observation that only 5 to 25% of a female's egg complement is released at any given time (approximately every 2 to 6 days) during a 3- to 6-week spawning period.  After hatching, larvae obtain nourishment from a yolk sac until they have reached a length of 1.5 to 2.0 mm.  During the larval stage, the young feed on phytoplankton and small zooplankton in the upper 10 to 50 metres of the water column.  After the larval stage, the juveniles swim, or ‘settle’, to the bottom, where they appear to remain for a period of 1 to 4 years.  These settlement areas are known to range from very shallow (< 10 m to 30 m) coastal waters to moderately deep (50 to 150 m) waters on offshore banks.  After this settlement period, it is believed that the fish begin to undertake the often-seasonal movements (apparently undirected swimming in coastal waters) and migrations (directed movements to and from specific, highly predictable locations) characteristic of adults.

 

Population sizes and trends

Estimates of the size of the breeding part of the population for Atlantic cod are available from two sources:  (1) abundance estimates of the mature part of the population, as derived from a fisheries-dependent model called a Virtual Population Analysis (VPA), and (2) catch rates of fish of reproductive age as determined from fisheries-independent research surveys.  The latter estimates tend to be more reliable although the former tend to extend further back in time.  The Canadian Department of Fisheries and Oceans (DFO) is the primary source of these abundance data.

Based on COSEWIC's guidelines for assigning status below the species level, and within the empirical and theoretical constructs of Evolutionarily Significant Units (Waples 1991), four populations are identified in the present report and, when data are available, trends in the numbers of breeding individuals are described for each.  Each of the populations includes cod found in more than one management unit, as delineated by geographical areas called NAFO (Northwest Atlantic Fishery Organization) divisions.  These divisions identify the cod stocks managed by the DFO.

Arctic Population:  Cod in this population are those confined to coastal lakes along Frobisher Bay and Cumberland Sound, and those inhabiting the marine environment east and southeast of Baffin Island, Nunavut (NAFO Divisions 0A, 0B).  Although little is known about cod inhabiting the marine waters in this area, they may be the ancestral source of the relict landlocked populations (7 are known or suspected) inhabiting lakes that receive intermittent tidal intrusions of salt water.  Limited data suggest that the lake populations mature at larger sizes than cod elsewhere in Canadian waters, and that their population sizes are relatively small (numbering hundreds of mature individuals).  Although there are no data on temporal trends in abundance, increased angling pressure has been identified as a concern by local inhabitants.

Newfoundland & Labrador Population:  Cod in this population inhabit the waters ranging from immediately north of Cape Chidley (northern tip of Labrador) southeast to Grand Bank off eastern Newfoundland.  For management purposes, cod in this population are treated as three separate stocks by DFO:  (1) Northern Labrador cod (NAFO Divisions 2GH), (2) "Northern" cod, i.e., those found off southeastern Labrador, the Northeast Newfoundland Shelf, and the northern half of Grand Bank (NAFO Divisions 2J3KL), and (3) Southern Grand Bank cod (NAFO Divisions 3NO).  Cod in this Population are at historically low levels of abundance.  The 3-generation rate of decline experienced by the Newfoundland & Labrador population was 97%.

Laurentian North Population:  Cod in this population combine the stocks identified for management purposes by DFO as (1) St. Pierre Bank (NAFO Division 3Ps) and (2) Northern Gulf of St. Lawrence (NAFO Divisions 3Pn4RS).  Respectively, these stocks are located north of the Laurentian Channel, along the south coast of Newfoundland and bordering Quebec.  Cod in this population are at or near historically low levels of abundance.  The 3-generation rate of decline experienced by this population was 81%; most of this decline can be attributed to the Northern Gulf cod stock.

Maritimes Population:  Cod in this population combine the stocks identified for management purposes as five separate stocks by DFO:  (1) Southern Gulf of St. Lawrence (NAFO Division 4T), (2) Cabot Strait (NAFO Division 4Vn), (3) Eastern Scotian Shelf (NAFO Divisions 4VsW), (4) Bay of Fundy/Western Scotian Shelf (NAFO Division 4X), and (5) cod found on the Canadian portion of Georges Bank (NAFO Division 5Zej,m).  The 3-generation rate of decline experienced by this population was 14%.  There is considerable variation in abundance trends within this population.  Southern Gulf cod, which comprise most of the cod in this Population, are at higher levels of abundance than they were 3 generations ago.  By contrast, Eastern Scotian Shelf cod are at historic lows and have continued to decline in the absence of directed fishing over the past decade.

 

Limiting factors and threats

The primary factor responsible for the decline of Atlantic cod was overfishing.  In some areas, reductions in individual growth, attributable to environmental effects or size-selective fishing mortality, may have exacerbated the rate of population decline; in some areas, increases in natural mortality may also have contributed to the decline.  It is important to note, however, that there is no evidence to suggest that the rates of growth and natural mortality experienced by cod in the 1980s were unprecedented.  Although hypotheses invoking factors other than fishing have been posited, there are inadequate data that would allow for definitive tests of these hypotheses.

The primary biological factors limiting the recovery of Atlantic cod south of Cape Chidley, Labrador, include:

1.    Collapsed age structure, loss of spawning components (e.g., the spring-spawning component on the Eastern Scotian Shelf), and/or reduced area occupied by spawners;

2.    Below-average recruitment rate in some parts of the range (Southern Grand Bank, St. Pierre Bank, Eastern and Western Scotian Shelf), but not others (NE Newfoundland Shelf, Northern and Southern Gulf of St. Lawrence);

3.    Higher-than-expected natural mortality of adults in some parts of the range of each population;

4.    Decline in individual growth rate in some areas within each population.

Identifiable threats to the recovery of Atlantic cod include directed fishing (a consequence of the setting of management quotas) and indirected fishing (a consequence of illegal fishing, catch misreporting, discarding, and bycatch from other fisheries).  Suspected threats to recovery include altered biological ecosystems, with concomitant changes to the magnitude and type of species interactions, and alterations to bottom habitat.  Among these species interactions, seal predation has been implicated as a negative influence on cod recovery in some areas, notably off Newfoundland and Labrador, and in the Northern Gulf of St. Lawrence.

 

Special significance of the species

Given its historical and contemporary importance to society, few species have been of greater significance in Canada.  After the short-lived Viking-based settlements on Newfoundland’s Northern Peninsula in the late tenth century, it was cod that brought the first Europeans to Newfoundland waters in the late fifteenth century, an economic venture that spawned one of the first permanent settlements in British North America (1612; Cupids, Newfoundland).  Until the early 1990s, Atlantic cod was the economic mainstay for Newfoundland and Labrador, as it was for a large part of the population in the Maritimes and along Quebec’s north shore and Gaspé Peninsula.  From a biological perspective, the Atlantic cod, which numbered approximately 2.5 billion spawning individuals as recently as the early 1960s, was one of the dominant species of the marine food web in the Northwest Atlantic.

 

Existing protection or other status designations

In Canada, the Atlantic cod is protected federally by the Fisheries Act and by the Oceans Act.  Several of the cod populations in Canadian waters are managed jointly with other countries.  For example, the Georges Bank cod stock (NAFO Division 5ej,m) is jointly managed by Canada’s DFO and the National Marine Fisheries Service in the United States.  The cod stocks inhabiting the Newfoundland & Labrador population and the offshore waters of the Arctic population are managed jointly by Canada and international fishing nations, such as Russia, Portugal and Spain, under the auspices of the Northwest Atlantic Fisheries Organization (NAFO).

Other Status Designations for Atlantic Cod:  IUCN: Vulnerable

Global Heritage Status Rank: G5

Summary of status report

The report suggests that, for designation purposes, Atlantic cod in Canada be recognized as four Populations, in accordance with known genetic, ecological, and demographic data, and in accordance with the guidelines detailed in Appendix F5 of COSEWIC’s Organization and Procedures Manual (Version 16, April 2002).

Regarding the assignment of risk, only the primary cause of the reduction in Atlantic cod (fishing) can be deemed reversible and understood.  However, fishing has not ceased in any of the populations (although it is restricted in some parts of some populations, such as the Eastern Scotian Shelf).  In the Laurentian North population, excessive fishing mortality has reduced the breeding part of the population, particularly in the Northern Gulf section of this population.  For the Newfoundland & Labrador population, it is evident, based on harvest rates estimated by DFO, that fishing is delaying recovery in parts of this population's range.

There are several factors that may influence one's perception of risk and, thus, the assignment of status to Atlantic cod.  These include (1) possibility of rescue from neighbouring populations, (2) changes to life history traits, (3) the degree to which census estimates of abundance reflect effective population sizes, and (4) differential responses by stocks to reductions in fishing.  These are detailed and discussed in full in the main body of the status report.

 

The populations, their 3-generation rates of decline, and threats to their recovery are summarized in the table below.
PopulationNAFO Management Division(s)Three-Generation Rate of DeclineThreats
Arctic0ABUnknownIncreased angling pressure in some lakes.
Newfoundland and Labrador2GHJ, 3KLNO97%

1.  Fishing (including legal, illegal, and unreported catches), notably on northern cod.

2.  Fishing-induced and natural changes to the ecosystem, resulting in altered levels of inter-specific competition and predation, notably predation by seals and fish on northern cod.

3.  Alteration of bottom habitat by fishing gear represents a potential but unevaluated threat.

Laurentian North3Ps, 3Pn4RS81%

1. Fishing (including legal, illegal, and unreported catches), representing a greater threat to Northern Gulf cod.

2.  Fishing-induced and natural changes to the ecosystem, resulting in altered levels of inter-specific competition and predation, notably predation by seals and fish on Northern Gulf cod.

3.  Alteration of bottom habitat by fishing gear represents a potential but unevaluated threat.

Maritimes4T, 4Vn, 4VsW, 4X, 5ej,m14%

1.  Fishing (including legal, illegal, and unreported catches), with the exception of Eastern Scotian Shelf cod.

2.  Fishing-induced and natural changes to the ecosystem, resulting in altered levels of inter-specific competition and predation, notably on Southern Gulf and Eastern Scotian Shelf cod.

3.  Alteration of bottom habitat by fishing gear represents a potential but unevaluated threat.



COSEWIC MANDATE

The Committee on the Status of Endangered Wildlife in Canada (COSEWIC) determines the national status of wild species, subspecies, varieties, and nationally significant populations that are considered to be at risk in Canada. Designations are made on all native species for the following taxonomic groups: mammals, birds, reptiles, amphibians, fish, lepidopterans, molluscs, vascular plants, lichens, and mosses.

 

COSEWIC MEMBERSHIP

COSEWIC comprises representatives from each provincial and territorial government wildlife agency, four federal agencies (Canadian Wildlife Service, Parks Canada Agency, Department of Fisheries and Oceans, and the Federal Biosystematic Partnership), three nonjurisdictional members and the co-chairs of the species specialist groups. The committee meets to consider status reports on candidate species.

 

DEFINITIONS

Species: Any indigenous species, subspecies, variety, or geographically defined population of wild fauna and flora.

Extinct (X): A species that no longer exists.

Extirpated (XT): A species no longer existing in the wild in Canada, but occurring elsewhere.

Endangered (E): A species facing imminent extirpation or extinction.

Threatened (T): A species likely to become endangered if limiting factors are not reversed.

Special Concern (SC)*: A species of special concern because of characteristics that make it particularly sensitive to human activities or natural events.

Not at Risk (NAR)**: A species that has been evaluated and found to be not at risk.

Data Deficient (DD)***: A species for which there is insufficient scientific information to support status designation.

*     Formerly described as "Vulnerable" from 1990 to 1999, or "Rare" prior to 1990.
**   Formerly described as "Not In Any Category", or "No Designation Required."
*** Formerly described as "Indeterminate" from 1994 to 1999 or "ISIBD" (insufficient scientific information on which to base a designation) prior to 1994.

 

The Committee on the Status of Endangered Wildlife in Canada (COSEWIC) was created in 1977 as a result of a recommendation at the Federal-Provincial Wildlife Conference held in 1976. It arose from the need for a single, official, scientifically sound, national listing of wildlife species at risk. In 1978, COSEWIC designated its first species and produced its first list of Canadian species at risk. Species designated at meetings of the full committee are added to the list.

Environment                  Environnement
Canada                         Canada

Canadian Wildlife           Service canadien
Service                         de la faune

The Canadian Wildlife Service, Environment Canada, provides full administrative and financial support to the COSEWIC Secretariat.