Pacific sardine (Sardinops sagax) COSEWIC assessment and status report: chapter 4

Distribution

Global range

The Pacific sardine is distributed from northern Mexico to southeastern Alaska, although the main centres of concentration range from southern California - northern Baja to the southern portions of British Columbia (Figure 2). Prior to the early 1900s’ collapse of the California sardine, it was generally accepted that there were three stocks within the California Current system: a northern stock [from northern Baja California (30°N) to Alaska (55°N)], a southern stock [off the coast of Baja (23-30°N)], and a Gulf of California stock (23-31°N). This classification was based on spawning ground distribution, growth rates, tagging studies, and serological evidence (Culley 1971, Felin 1954, Hart 1943a, Janssen 1948, Marr 1957, 1960, Murphy 1966, Vrooman 1964). Radovich (1962) postulated the existence of an additional far northern population in the Pacific Northwest based on differing growth rates and scale patterns. However, other researchers questioned this (Marr 1960, Murphy 1966) and recent studies suggest that variation in life history traits is more likely the effect of environmental variation than of genetic differences (Hedgecock et al. 1989). They also suggest a single genetic stock of sardine in the California current system (Parrish et al. 1989, Hedgecock et al. 1989). For instance, Hedgecock et al (1989) found similar allozyme frequencies throughout the spawning distribution of the Pacific sardine, and the same rare alleles in widely separated localities. This suggests that there has been substantial gene flow among populations and does not provide evidence of the genetic differentiation that would support the existence of discrete stocks.

Canadian range

The Pacific sardine resides seasonally in Canadian waters, migrating northward from California in the spring to the rich feeding grounds off Vancouver Island and returning south in the fall. It was fished extensively in the Pacific northwest during the first half of the 20th century, and disappeared entirely from this area by the late 1940s. Some sardines over-wintered in inlets along the west coast of Vancouver Island rather than migrating south in the fall (Hart 1938, 1943a). Hart (1943a) concluded that “some of the tag recoveries indicate that these pilchards [fish taken in inlets] are a part of the general population cut off from participation in the general movement by local conditions rather than a special local population”. After an absence of almost 50 years, sardines re-appeared in Canadian waters in 1992 (Hargreaves et al. 1994). As in the past, sardines have been found over-wintering in the inlets along the west coast of Vancouver Island and the Central Coast of British Columbia. This has been most pronounced during the 1997 and 1998 warm water years. These occurrences may represent schools of sardines trapped in warm water cells since they were coincident with large die-offs of fish that occurred in these areas in the winter (personal communication - G. Traxler, Fisheries and Oceans Canada, Pacific Biological Station, Nanaimo, B.C. 14 November 2001). At this time there is no evidence to support the existence of reproducing resident populations of Pacific sardine in Canada.

Figure 2. Distribution of the Pacific sardine, its major spawning grounds, nursery areas, and major fishery localities prior to 1950 (redrawn from Culley 1971). Spawning also occurs in the Gulf of California but locations are unknown.

Figure 2.  Distribution of the Pacific sardine, its major spawning grounds, nursery areas, and major fishery localities prior to 1950

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