Redfish

Redfish, known commercially as ocean perch, occur on both sides of the Atlantic Ocean. They are normally found along the slopes of fishing banks, deep channels, and off the edge of the continental shelf usually at depths of 100 - 700 m. In the northwest Atlantic, redfish range from Baffin Island in the north to the coast of New Jersey in the south. Two species of redfish occur on the Scotian Shelf. Acadian redfish, Sebastes fasciatus, occur in the deep basins and at the edge of the continental shelf. Beaked redfish, Sebastes mentella, occur in the deeper waters off the continental shelf and in the Laurentian Channel. These species are difficult to distinguish and as a result commercial catches and research survey catches are normally not separated.

Redfish are ovoviviparous, as fertilization is internal, and the young are born live. Mating occurs in the fall and females carry the developing young until release from April to July of the following year. Redfish are slow growing and long lived with ages of >30 years and sizes of >50cm having been observed. The young grow to about 8cm in their first year of life and then take 8-10 years to reach a commercial size of 25cm. S. fasciatus reaches a smaller size than S. mentella. Growth is usually faster in the southern part of the range than in the northern portion, and females grow faster than males. The average length at which 50% of the redfish on the Scotian Shelf are mature is about 24 to 26cm for females and 16 to 17cm for males. In the Gulf of Maine it is about 22cm for females and 19 to 22cm for males.

Redfish are semipelagic; feeding is thought to take place at night, when redfish rise off the bottom. Food consists primarily of pelagic crustaceans such as amphipods, copepods, and euphausids Fish become an important part of the diet as redfish increase in size.

Fishery

Management Unit 3 for redfish consists of Statistical Unit Areas 4Wdehkl and 4X. The fishery is primarily conducted using bottom otter trawls with small mesh codends (110mm). Genetic research has shown that the redfish in Unit 3 are almost exclusively S. fasciatus. As a result the fishery in Unit 3 is treated as a single species fishery.

The Unit 3 management area for redfish was first implemented in the 1993 Groundfish Management Plan. Redfish in this area were previously managed as part of the larger 4VWX management area. The 10,000t Total Allowable Catch (TAC), introduced in 1993 was based on the 1991 TAC for the previous management area prorated by historical (1981-90) catches in the Statistical Unit Areas which comprise Unit 3. The first scientific description of Unit 3 Redfish was a report to the Fisheries Resource Conservation Council in 193 which was used as a basis for a recommendation for a 10,000t TAC for 1994. The TAC was reduced to 9000t in 2000.

Landings data is available for Unit 3 Redfish dating back to 1960. In the early 1960s the fishery was dominated by foreign landings with the Canadian catch being less than 1000t. There was a reduction in landings in the late 1960s before increasing to a high in 1971 of 25,600t total landings. Canadian landings in that year reached a record 11,500t. Through the 1970s there was a reduction in both foreign and Canadian landings, reaching a low of 2700t in 1979. By the late 1970s Canadian landings dominated the redfish catches with the foreign fishery decreasing to a point where foreign redfish landings were essentially eliminated by 1985. Canadian Unit 3 Redfish landings have remained significantly below the TAC since the 1980s.

The distribution of the fishery has changed significantly since 1960. In the 19so's a significant portion of the redfish landings came out of the 4W portion of Unit 3. In some years 4W contributed more than 50% of the overall landings. This proportion declined through the 1970s and since 1980 the fishery has been dominated by catches for the 4X (western portion) of Unit 3.

Research

Redfish abundance and biomass in Unit 3 since 1970 using the DFO Summer Research Vessel Survey. The survey shows a slight declining trend in total biomass from 1970 through the 1990s with a subsequent increase since about 2000. Biomass for the portion of the population under 22cm (proxy for immature) has shown an increase since about 1995.

Total survey abundance shows little trend from 1970-1990, however shos an increasing trend since 1990. Although there is an increase in abundance of all size classes the increase is dominated by individuals less than 22cm (immature).

The distribution of survey catches have shown a trend towards the western portion of the survey area over the survey time series.