posted on November 01, 1998 13:57
D. G. Parsons, E. B. Colbourne, G. R. Lilly and D. W. Kulka
Science Branch, Department of Fisheries and Oceans
P. O. Box 5667 St. John's, Newfoundland, Canada A1C 5X1
Source - Journal of Northwest Atlantic Fishery Science, Volume 24: 1-26
The purpose of this paper is to consolidate information presented to the Scientific Council of NAFO during 1993-95 on northern shrimp (Pandalus borealis) on Flemish Cap. Also included are sections on oceanography of the area, general biology of the species and by-catch of fish in the commercial fishery for shrimp.
Oceanographic data describe the habitat in relation to bathymetry, temperature, salinity and circulation. Shrimp distribution, determined from research surveys, commercial fishery data and stomach contents of cod (Gadus morhua), occurred within depths of 200-600 m where temperatures and salinities were approximately 4.0°C and 34.0 PSU, respectively. An anticyclonic gyre over the centre of the Cap dominated the circulation, providing a mechanism for the retention of shrimp larvae in the area. The bottom trawl fishery for shrimp, which began in 1993, increased rapidly through the participation of vessels from several nations. Catches decreased from about 28 000 tons in 1993 to 24 000 in 1994 but increased to 33 000 in 1995. Fishery regulations initially dealt with limiting by-catch, primarily redfish (Sebastes sp.), and concerns about discard mortality led to mandatory use of sorting grates in shrimp trawls in 1994. A substantial decline in redfish by-catches in 1995 was coincident with a decrease in the bar spacings of sorting grates and with an increase in individual size and decrease in numbers of a strong redfish year-class.
Catch-effort data from the fishery (1993-95) and research trawl surveys (1988-95) provided indices of biomass which showed a large increase between 1990 and 1992 and a decline, thereafter. Biological sampling for length, sex and maturity from both sources were used to determine age and growth. Shrimp on the Flemish Cap show life history characteristics similar to warm water populations at early life stages and to cold water populations later in life, consistent with influences of both the Gulf Stream and Labrador Current in the Flemish Cap area. Several species of finfish in the Flemish Cap community are predators and/or competitors of shrimp but relationships between the abundance of shrimp and the abundance of any other species have not been investigated.
Language - English
Publisher - Northwest Atlantic Fisheries Organization (NAFO), Dartmouth, N.S., Canada
Publication Date - November 1998
Publication Type - Journal Article