An Interim Report the Number of Adult Saison and Grilse
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3£> % éfà7 v . • V* AN INTERIM REPORT ON THE NUMBER OF ADULT SAISON AND GRILSE IN HERRING PURSE-SEINE CATCHES FROM SOUTHERN BRITISH COLUMBIA IN 1963-64 by D. N. Outram Fisheries Research Board of Canada Biological Station, Nanaimo, B. C. This report is the result of a preliminary analysis of the data , using estimated catches. The final report, incorporating any changes that full analyses of the data and of catches as reported on Department of Fisheries sales slips require, will be published later. March, 1964 > •* A* ^ THE NUMBER OF ADULT SALMON AND GRILSE IN HERRING PURSE-SEINE CATCHES FROM SOUTHERN BRITISH COLUMBIA IN 1963-64 I. INTRODUCTION A fleet of about 80 seine-boats removes over 100,000 tons of herring annually from the coastal waters of southern British Columbia. The fishery depends on schools of fish that congregate in the "inside passages" during the winter months , prior to spawning in early spring. From late September onwards herring stocks move into the Strait of Georgia by two main routes: (l) from the north through Johnstone Strait and Discovery Passage and (2) from the south through the Strait of Juan de Fuca. Herring fishing may take place in daylight or at night. Night fishing frequently involves the use of bright, mercury vapour lamps to attract and concentrate dispersed schools of herring. This- method of fishing , known as "pitlamping", came into prominence during the 1959-60 fishing season and has accentuated the fears of other fishermen and of the public that significant numbers of other species of fish , particularly salmon, were being taken in herring catches, especially in the Strait of Georgia.! Substantial numbers of dogfish, young and adult Pacific cod , hake, and whiting^, were observed in the 1963 landings. Less frequently noted in the deliveries were sole of various species, skate, midshipmen, rockfish, pilchards, sablefish and squid. During the winter of 1963, the Department of Fisheries and the Fisheries Research Board of Canada initiated a joint program to assess the extent to which salmon occur in herring catches in southern British Columbia. This is an interim report on the results obtained in 1963. The catches used are the estimates appearing in weekly reports of the district supervisor. The final report must await the analysis of the catch as reported on the sales slip record. Preliminary observations by personnel of the Biological Station, Nanaimo, B. C. had been carried out during the winters of 1959, 1960 and 1961. The results were published in Manuscript Report No. 753 of the Biological Station, Nanaimo, in June 1963. II. METHOD OF CHECKING SALMON IN CATCHES The reduction plants at Steveston, B. C. were examined to determine where it was possible to carry out checks of the number of salmon in herring deliveries. The reduction plant at Imperial Cannery was the only plant having an adequate observation site. A check-point was set up on the roof, beside a 2 - slow-moving conveyor belt , Herring were pumped from the hold of the seiner onto a long wire-meshed conveyor , washed , and carried up across the roof towards the observers and thence to storage bins inside . With a staff of four observers , three on duty at a time , it was possible to check all landings by a fleet of 24 seiners on an around-the-clock basis from September 26 to December 2. Two observers were stationed beside the conveyor belt . It was estimated they removed about 80 per cent of the salmon mixed with the herring . The third observer kept a careful check of the number of salmon removed by plant personnel and seiner crew . The numbers of salmon found should be considered to be minimum estimates as reports from fisheries inspectors on the fishing grounds indicated that some salmon were at times released at sea . III . RESULTS The 1963 winter herring fishing shifted from one area to another depending on weather , quota extensions , and the availability of herring . Consequently , some localities were fished infrequently while others were fished for eight weeks . During the period of the survey over 24 , 000 tons of herring were examined for salmon , about one-quarter of the total catch in District 3. A total of 3, 655 adult salmon and 7, 091 grilse were found . Table I shows the actual numbers of salmon and grilse found each week , the numbers per hundred tons of herring and estimates of the numbers of salmon and grilse in the total weekly catch . In Table II the actual numbers of adult salmon and of grilse , and the numbers per 100 tons of herring ( Figs . 1-4 ) are shown by fishing localities and weeks . A . Northern Georgia Strait and Queen Charlotte Sound ( l ) Mainland inlets (Jervis Inlet , Bute Inlet , Loughborough Inlet , Knight Inlet and Belleisle Sound ) - Fig . 1. Except for Knight Inlet these localities were not heavily fished . The numbers of salmon and grilse found were negligible , not exceeding 5 per 100 tons of herring in any locality. A search of 227 tons landed during the week ending October 19 from Belleisle Sound did not yield any salmon , while observations on half of the 5, 600 tons taken from Knight Inlet during the two- week period ending October 19 showed that there were only 5 adult salmon and 2 grilse per 100 tons of herring (Table II ) . Catches from Knight Inlet in November (1, 260 tons ) were not searched , probably because all these fish went to other reduction plants . ( 2) Upper East Coast of Vancouver Island (Clio Channel and vicinity only ) - Fig . 1. Part of this sub-district , knight Inlet and Belleisle Sound , was con- sidered in the previous section on mainland inlets . While herring were also - 3 taken in Retreat Pass, off Mexicans Point and in Seymour Inlet, only those catches from Clio Channel were examined for salmon. Clio Channel is sometimes a productive herring fishing ground but in the winter of 1963 only 276 tons were taken. An examination of the deliveries during the week ending October 19 found 43 adult salmon and 74 grilse or 15 adults and 27 grilse per 100 tons of herring (Table II), a relatively low ratio of occurrence. Previous observations carried out during the winter of 1959 on 206 tons landed from Bones Bay during the week ending November 26 showed no salmon, while a check of 271 tons from Blackfish Sound in early October 1961 yielded only 9 adults and 45 grilse per 100 tons of herring (Table III). (3) Middle East Coast of Vancouver Island (Discovery Passage, Deepwater Bay , and Denman Island) - Fig. 2. The middle east coast sub-district yielded 20,347 tons of herring in 1963-64. Of this amount 1,641 tons were caught in the summer fishery. In the winter fishery , 475 tons were taken from Pender Harbour or Jervis Inlet in Area 16, 2,899 tons from near Denman Island in Area 14, and 15,343 tons^in Area 13 in the vicinity of Discovery Passage. ^Discussed in a previous section - Mainland inlets - see Fig. 1. The sub-district quota of 10,000 tons was taken on October 15. The most intense fishing was in Discovery Passage where 7,891 tons were caught, compared to 739 tons from Denman Island. On October 12, shortly before the quota was taken, a part of the Discovery Passage fishing grounds - Deepwater Bay - was closed to herring fishing because of the large numbers of salmon and grilse present in the herring catches. This area was not re-opened when a quota extension of 10,000 tons was granted on November 14. The extension was taken by December 2, with fishing again being more intense in Discovery Passage (7,452 tons)than near Denman Island (2,160 tons). About 22% of the herring landings from Discovery Passage in October were searched for salmon and grilse , and about 24% of the landings from Denman Island. In November about 5% of the landings from Discovery Passage and 19% of the landings from Denman Island were searched. The incidence of salmon in herring catches from Discovery Passage and Denman Island are discussed below: Discovery Passage (Fig. 2). This region includes Discovery Passage proper, Granite Bay and Deepwater Bay. The numbers of grilse in the herring catches (Table II) increased sharply from relatively modest numbers (12 per 100 tons) during the week ending October 5 to large numbers (344 per 100 tons)during the week ending October 19 (fishing stopped on October 15). The incidence of grilse in the landings during the period from November 14 to December 2 was much lower than in October; the numbers varied from 76 per 100 tons of herring on November 14 to 16, to none on December 1 and 2. Two 4 species of grilse were identified , coho and Chinook. The former were between 4 and 20 times as numerous as the latter and were responsible for producing the marked changes in numbers noted (Table IV). The numbers of young Chinook per 100 tons of herring remained relatively constant throughout the season, varying between 2 and 38 per 100 tons of herring. The numbers of adult salmon did not fluctuate as widely as did the numbers of grilse, although they showed the same general pattern of variation. Numbers increased steadily from 47 per 100 tons of herring during the week ending October 19. In November the numbers declined from 63 per 100 tons to none. Chum was the dominant species of adult salmon particularly in October, the numbers varying between 40 and 77 per 100 tons of herring (Table IV). The other three species were about equally abundant, between 2 and 9 of each occur- ring per 100 tons of herring.