Pighead prickleback COSEWIC assessment and status report: chapter 2

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COSEWIC Executive Summary

Houston(1988) provided the first report of pighead pricklebacks, Acantholumpenus mackayi, for COSEWIC. In April 1989, COSEWIC designated the pighead prickleback as Special Concern. This report is an update that includes findings of Bond, Hopky, Lacho, Ratynski and others (see references) as well as the author’s own observations.

Species Information

This marine fish is a member of the family Stichaeidae. It has a slender, eel-like body with numerous dorsal rays extending along the full length of its back. It is distinguished from other stichaeids by thickened lips, stout head, and proportionally smaller eyes. Although the proper common name for this prickleback is the pighead (American Fisheries Society), this species is sometimes called the blackline prickleback.

Distribution

Pighead pricklebacks are known from three areas: 1) Sea of Okhotsk and Sea of Japan; 2) Bering Sea; and 3) Canadian Beaufort Sea. The Beaufort Sea population may extend from Phillips Bay, Yukon to Tuktoyaktuk Harbour and Liverpool Bay, Northwest Territory.

Habitat

Larvae are planktonic and disperse in ocean currents. Juveniles and adults occupy sand, silt or mud bottoms. They are found mostly in shallow, saline areas in or below the halocline, although adults and larvae can tolerate diluted seawater above the halocline. They are also found in brackish waters of lakes and river mouths as well as more saline waters. They occur as deep as 56 m in Bristol Bay (Bering Sea) and as deep as 26 m depths in Tuktoyaktuk Harbour. Their distribution probably changes with seasonal and daily shifts of the thermocline and halocline.

Biology

The pighead prickleback feeds on benthic invertebrates. At Tuktoyaktuk, the maximum known age is 16 years, and adults mature at 4 to 5 years. Males are generally larger than females, reaching lengths close to 50 mm compared to 47 mm for females. Although very little is known about their physiology, they survive long periods under ice and in darkness.

Population Sizes and Trends

The abundance of pighead pricklebacks in Canada is poorly known. A single population estimate for Tuktoyaktuk Harbour suggests 2100 individuals of which 1600 may be mature fish. Populations likely have dominance of a few age classes. No trend data exist.

Limiting Factors and Threats

Little is known about the limiting factors and threats to this species. There may be gaps in recruitment strength, and strong age classes may be necessary to offset periods of poor year-class survival. Their distribution may be clumped and thus susceptible to local perturbation, including the potential long-term effects of global warming and increased freshwater flows into their saline habitats. The oil industry may impact the species as leakage sinks into saline bottom-water.

Special Significance of the Species

The Canadian population is unique in that it represents the most eastern occurrence of the species. It also appears to be isolated from the Bering Sea populations. The species does not have direct economic value, but does have ecological roles as a consumer of bottom organisms and as likely prey for seabirds, whales, seals and predatory fish.

Existing Protection

Canadian and territorial statutes regulate habitat/environmental standards in areas where the species lives. The COSEWIC designation of “special concern” in 1989 raised its profile in habitat and environmental assessments. The federal Fisheries acts alleviate some threats, especially pollutants in harbours such as Tuktoyaktuk where authorities can respond to spillage of contaminants on ocean bottoms. There is no direct concern expressed for pighead pricklebacks by the Northwest Territories government (2002).

COSEWIC History

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. On June 5, 2003, the Species at Risk Act (SARA) was proclaimed. SARA establishes COSEWIC as an advisory body ensuring that species will continue to be assessed under a rigorous and independent scientific process.

COSEWIC Mandate

The Committee on the Status of Endangered Wildlife in Canada (COSEWIC) assesses the national status of wild species, subspecies, varieties, or other designatable units that are considered to be at risk in Canada. Designations are made on native species and include the following taxonomic groups: mammals, birds, reptiles, amphibians, fishes, arthropods, molluscs, vascular plants, mosses, and lichens.

COSEWIC Membership

COSEWIC comprises members from each provincial and territorial government wildlife agency, four federal organizations (Canadian Wildlife Service, Parks Canada Agency, Department of Fisheries and Oceans, and the Federal Biosystematic Partnership, chaired by the Canadian Museum of Nature), three nonjurisdictional members and the co-chairs of the species specialist and the Aboriginal Traditional Knowledge subcommittees. The committee meets to consider status reports on candidate species.

Definitions (after May 2003)

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)^Footnote1

A species of special concern because of characteristics that make it particularly sensitive to human activities or natural events.

Not at Risk (NAR)^Footnote2

A species that has been evaluated and found to be not at risk.

Data Deficient (DD)^Footnote3

A species for which there is insufficient scientific information to support status designation.