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Winter Skate (Leucoraja Ocellata)

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COSEWIC
Assessment Summary

 

Assessment Summary – May 2005

Common name:

Winter Skate (Southern Gulf population)

Scientific name:
Leucoraja ocellata

Status:
Endangered

Reason for designation:
The species possesses life history characteristics that increase vulnerability to exploitation, that reduce rate of recovery, and that increase the risk of extinction. These characteristics include delayed age at maturity, long generation time, low fecundity, and consequently slow population growth rate. Narrow latitudinal ranges and a high degree of endemicity have been documented for the skate family worldwide. This population appears to have a restricted distribution, based on distributional maps of fisheries-independent survey catches. Individuals from this population mature at a significantly smaller size than those found elsewhere in Canadian waters. Abundance of mature individuals in the Southern Gulf of St. Lawrence is estimated to have declined 98% since the early 1970s, and is now at a historically low level. The probable cause of decline is an unsustainable rate at which they were captured as bycatch in fisheries directed at other groundfish species.

Occurrence:
Atlantic Ocean

Status history:
Designated Endangered in May 2005. Assessment based on a new status report.

 

Assessment Summary – May 2005

Common name:

Winter skate (Eastern Scotian Shelf population)

Scientific name:
Leucoraja ocellata

Status:
Threatened

Reason for designation:
The species possesses life history characteristics that increase vulnerability to exploitation, that reduce rate of recovery, and that increase the risk of extinction. These characteristics include delayed age at maturity, long generation time, low fecundity, and consequently slow population growth rate. Narrow latitudinal ranges and a high degree of endemicity have been documented for the skate family worldwide. This population appears to have a restricted distribution, based on distributional maps of fisheries-independent survey catches. Individuals from this population mature at a significantly larger size than those in the Southern Gulf and have been reported to mature at a significantly different age than those inhabiting waters further south. Abundance of mature individuals on the Eastern Scotian Shelf is estimated to have declined by more than 90% since the early 1970s and is now at a historically low level. The area occupied by the population appears to have declined significantly since the mid 1980s. Larger, older individuals have been severely depleted from this population, producing a significant truncation in the length distribution of the population over time. The probable cause of the decline is an unsustainable rate at which they were captured as bycatch in fisheries directed at other groundfish species. They have been caught, and continue to be caught, in a directed fishery for skate, although current reported catches are low.

Occurrence:
Atlantic Ocean

Status history:
Designated Threatened in May 2005. Assessment based on a new status report.

 

Assessment Summary – May 2005

Common name:

Winter skate (Georges Bank-Western Scotian Shelf-Bay of Fundy population)

Scientific name:
Leucoraja ocellata

Status:
Special Concern

Reason for designation:
The species possesses life history characteristics that increase vulnerability to exploitation, that reduce rate of recovery, and that increase the risk of extinction. These characteristics include delayed age at maturity, long generation time, low fecundity, and consequently slow population growth rate. The area of occupancy of this species has been stable. Estimates of population status on Georges Bank show no discernible trend over time. Abundance elsewhere appears to have been stable over time. There is a high probability that the population receives immigrants from the species inhabiting the American portion of Georges Bank. The population is subjected to bycatch in fisheries for other groundfish shellfish species. There are directed fisheries for this species in U.S. waters.

Occurrence:
Atlantic Ocean

Status history:
Designated Special Concern in May 2005. Assessment based on a new status report.

 

Assessment Summary – May 2005

Common name:

Winter skate (Northern Gulf-Newfoundland population)

Scientific name:
Leucoraja ocellata

Status:
Data Deficient

Reason for designation:
The species exists in low concentrations in the Northern Gulf of St. Lawrence, in the coastal waters off the southern coast of Newfoundland, and on the southern portion of the Grand Bank. A quantitative analysis of spatial and temporal variation in population size is not possible because of the infrequency with which the species is caught. The population is subjected to bycatch.

Occurrence:
Atlantic Ocean

Status history:
Species considered in May 2005 and placed in the Data Deficient category. Assessment based on a new status report.