Shortfin mako (Isurus oxyrinchus) COSEWIC assessment and status report: chapter 5

Habitat

Habitat requirements

Specific habitat requirements have not been well described. Temperature appears to be a critical component defining shortfin mako distribution. They prefer temperate to tropical waters and are rarely found in waters less than 16°C. Preferred water temperature is between 17-22°C and consequently, in the Atlantic, they are often associated with Gulf Stream waters (Compagno 2001). They occur from the surface to 500 m depths. Typically they occur well offshore but have occasionally been observed in littoral zones. In the western North Atlantic they move onto the continental shelf when surface temperatures exceed 17°C. In the eastern North Pacific juveniles range into southern California waters and tend to stay near the surface, with little tendency to descend into cold subsurface waters. Off California, small sharks were found to stay near the surface above 20 m depth and in waters near 21°C (Holts and Bedford, 1992). Recent data from eight juvenile shortfin makos radio tagged off southern California confirms previous studies that juveniles spend most of their time (~80%) within 12 m of the surface (Sepulveda et al. 2004).

Habitat trends

The typical offshore habitat of this species is not readily affected by either anthropogenic or catastrophic natural events. Anthropogenic shifts in ocean temperatures (i.e., global climate change) could influence the distribution and habitat of this species, but this has not yet been investigated.

Habitat protection/ownership

Much of the preferred habitat of the shortfin mako lies outside of any nation’s exclusive economic zone. There are no agreements for the protection of their habitat, nor have any other protective measures such as fishing exclusion zones been established. Likewise, in Canadian waters there are no habitat-related protective measures for shortfin mako.

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