Striped bass (Morone saxatilis) COSEWIC assessment and status report: chapter 2

Executive Summary

Striped Bass

Morone Saxatilis

Species information

The striped bass, Morone saxatilis, is a species typical of eastern North American estuaries and coastal waters. It is anadromous, i.e., spawning, incubation and early larval development occur in freshwater and the juveniles migrate downstream to brackish water and eventually salt water to feed and grow for several years before reaching maturity.

The striped bass has an elongated, laterally compressed body, a triangular head and a large mouth, with protruding lower jaw. It has two separated dorsal fins, the first of which is spiny. It has a dark olive-green to black back, paling on the sides to silvery, and a white belly. It has seven or eight horizontal dark stripes along its sides following the scale rows. Males reach sexual maturity at about three-years-of-age, which corresponds to a total length of over 30 cm in Canadian waters. Females reach sexual maturity at about four- or five-years-of-age (over 40 cm in length).

Distribution

The natural range of the striped bass extends along the Atlantic coast of North America, from the St. Lawrence Estuary to the St. Johns River in northeast Florida. Native striped bass populations have also existed in the tributaries of the Gulf of Mexico, from the Suwannee River in northwestern Florida to Lake Pontchartrain in Louisiana.

The species was introduced on the U.S. Pacific coast in the late 1800s, where it became established. The striped bass can live and, in some cases, complete its entire life cycle in freshwater. Many lakes and reservoirs in the southern U.S. have been stocked with striped bass to promote the sport fishery.

There is historical evidence of striped bass spawning in five rivers of Eastern Canada: the St. Lawrence Estuary, the Miramichi River in the southern Gulf of St. Lawrence, and the Saint John, Annapolis and Shubenacadie rivers in the Bay of Fundy.  Striped bass still spawn in the Miramichi (southern Gulf) and Shubenacadie (Bay of Fundy) rivers. These two populations are isolated and genetically distinct. The most recent evidence of spawning activity in the three other rivers (St. Lawrence, Saint John and Annapolis) dates back some 20 years or more. Striped bass from the Shubenacadie River may come into contact with bass from U.S. rivers, which feed in the Bay of Fundy in summer, but they do not appear to reproduce with them.

Habitat

In striped bass, spawning occurs in freshwater and occasionally brackish water. Egg incubation and larval and young-of-the-year development correspond to a gradual movement downstream to saltwater. In summer, immature and adult bass feed in estuaries and coastal waters.

A particular feature of Canadian striped bass populations is that they overwinter in rivers in order to escape the cold ocean waters.

Biology

In Canada, mature striped bass spawn in late May or early June. Egg incubation lasts two to three days.  On hatching, the larvae have a yolk sac. The yolk reserves are used for about one week. When they begin to feed, their survival is closely dependent on the quantity of zooplankton available in the water column. The abundance of offspring produced by a given spawning population can vary from year to year, depending on whether the early development stages find conditions favourable to their survival. On completion of the larval stage, which lasts approximately one month, a series of morphological changes occur until the juveniles attain the characteristic shape of the species, which they keep as adults. In eastern Canada, young-of-the-year that reach approximately 100 mm in length seem to have a better chance of surviving their first winter than smaller individuals.

Fish over one year require an abundant food supply – invertebrates or fish – in order to grow, but they are able to move to the food source to meet their food requirements. Striped bass travel along the coast in schools of same-size fish to feed, and can cover tens of kilometres a day.

The first maturation of reproductive organs can occur at about four-years-of-age in some females. However, most do not spawn until of five-years-of-age. Males reach reproductive age a little earlier, at three- or four-years-of-age.

Population sizes and trends

On three of the five Canadian rivers that have supported striped bass populations (Saint John, Annapolis and St. Lawrence), no evidence of spawning has been observed and no catches of local bass have been authenticated for over two decades. In contrast, the Shubenacadie River population still appears to produce new individuals.

The only spawning site of the southern Gulf striped bass population is a limited section of a branch of the Miramichi River. Outside the spawning season, individuals from this population move along the east coast of New Brunswick where, until recently, they were taken in fishing gear. The increasingly strict regulation of harvesting followed by the complete closure of the commercial and recreational striped bass fishery seems to have limited fishing mortality and to have allowed the population to begin to recover.

Limiting factors

Canadian and U.S. striped bass studies have shown that overfishing by commercial and recreational fishers may have decimated some populations.

The alteration of spawning, incubation or rearing habitat can also compromise reproduction in this species.

Special significance of the species

Striped bass are prized for their fight and their meat. Bones of this species have been found during archaeological digs of Amerindian camp sites or inns dating back to the beginning of European colonization. Today, many fishers in the United States and Canada still fish striped bass. The species supports a recreational/tourism activity that has major economic benefits for some regions.

Apart from its interest as a long-standing fisheries species, striped bass is an important component of the biodiversity of aquatic ecosystems. The species is typically associated with estuaries and coastal waters, where it is one of the most important piscivorous species. An abundant striped bass population is an indicator that a river and its estuary are in good condition: the species requires high quality spawning and nursery habitat and abundant aquatic species for food.

Existing protection

Canadian and U.S. experience has shown that conservation considerations should be taken into account in the harvesting of striped bass. The evidence of a decline in striped bass abundance in the southern Gulf in the 1980s and 1990s led to the gradual introduction, beginning in 1992, of measures designed to limit catches. Commercial striped bass fisheries were closed and the recreational fishery was regulated for the first time. In 1993, the principle of a conservation requirement of 5,000 spawners was introduced. Population estimates below that level led to the complete closure of the commercial fishery, including bycatch, and to mandatory catch and release by recreational anglers in 1996. In 2000, all recreational striped bass fisheries were closed and First Nations’ allocations for social and ceremonial purposes were suspended. As a result of the increasingly stringent measures, the population appears to have begun to recover in 2001. The same approach is expected to be adopted to manage the harvesting of the Shubenacadie River striped bass population.

Three of the five Canadian populations have not shown evidence of spawning activity for over 20 years. No Canadian populations have been designated.

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. Species designated at meetings of the full committee are added to the list. On June 5th 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 for 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 agencies (Canadian Wildlife Service, Parks Canada Agency, Department of Fisheries and Oceans, and the Federal Biodiversity Information Partnership, chaired by the Canadian Museum of Nature), three non-government 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 (November 2004)

Wildlife Species
A species, subspecies, variety, or geographically or genetically distinct population of animal, plant or other organism, other than a bacterium or virus, that is wild by nature and it is either native to Canada or has extended its range into Canada without human intervention and has been present in Canada for atleast 50 years.

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

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

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

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

Special Concern (SC)*
A wildlife species that may become a threatened or an endangered species because of a combination of biological characteristics and identified threats.

Not at Risk (NAR)**
A wildlife species that has been evaluated and found to be not at risk of extinction given the current circumstances.

Data Deficient (DD)***
A wildlife species for which there is inadequate information to make a direct, or indirect, assessment of its risk of extinction.

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

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