White shark (Carcharodon carcharias) COSEWIC assessment and status report: chapter 5

Habitat

Habitat requirements

The white shark occurs in both inshore and offshore waters, from the intertidal to the upper continental slope and mesopelagic zone. Known bathymetric range is from just below the surface to just above the bottom down to a depth of at least 1,280 m (Bigelow and Schroeder 1948). It occurs in the breakers off sandy beaches, off rocky shores, and readily enters enclosed bays, lagoons, harbours, and estuaries, but does not penetrate brackish or fresh waters to any extent (Compagno 2001). Known temperatures from which the white shark has been recorded range from 5 to 27°C (Nakaya 1994; Boustany et al. 2002). Off California this species seems more abundant at temperatures of 14-15°C than at 11°C or below (Compagno 2001). The white shark is a wide-ranging, nomadic species capable of crossing ocean basins as it occurs sporadically off oceanic islands such as Hawaii (Taylor 1985) and the Azores (Compagno et al. 1997). Movement of this species from coastal waters into oceanic waters far offshore is further supported by a recent satellite tracking study (Boustany et al. 2002).

Habitat trends

It is unknown to what degree habitat deterioration has contributed to the apparent global decline of this species. The Australia and Madagascar CITES Proposal (2004) makes the case that inshore coastal feeding and breeding habitats of white sharks have deteriorated due to increased fishing pressure, pollution resulting in bioaccumulation, and possible prey depletion (Australia and Madagascar CITES Proposal 2004). In Canadian waters, both Atlantic and Pacific, there are no known activities altering the habitat and hence abundance or distribution of white sharks. For the purpose of this report, fisheries interactions are a cause of mortality and not a habitat issue.

Habitat protection/ownership

There are some marine protected areas in California that overlap with known important white shark areas. Generally, there has been little effort to protect white shark habitat.

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