| Status of common thresher sharks, Alopias vulpinus, along the west coast of North America : updated stock assessment based on alternative life history - :18085 | National Marine Fisheries Service (NMFS)
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Status of common thresher sharks, Alopias vulpinus, along the west coast of North America : updated stock assessment based on alternative life history
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Status of common thresher sharks, Alopias vulpinus, along the west coast of North America : updated stock assessment based on alternative life history
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    "Common thresher sharks (Alopias vulpinus) along the west coast of North America are seasonally distributed in coastal waters from British Columbia, Canada to central Baja California, Mexico. Juvenile common thresher sharks tend to remain in shallow, nearshore areas over the continental shelf, especially within the Southern California Bight (SCB), which is an important nursery area. The horizontal distributions of common and bigeye thresher sharks are thought to overlap partially, with bigeye thresher sharks generally exploiting deeper waters. In contrast, there is relatively little overlap in the distributions of common and pelagic thresher sharks, except for years with large El Nino-Southern Oscillation (ENSO) events, when the distribution of pelagic thresher sharks shift northwards. In this assessment, common thresher sharks along the west coast of North America are assumed to be a single, well-mixed stock. This assumption is supported by their genetics, tagging data, and seasonal movements. The mitochondrial genetic sequences of common thresher sharks from California waters are not significantly different from Oregon-Washington waters but both are significantly different from other sampling locations, noting that there have not been any published comparisons with samples from Mexico. There is also no evidence of pupping and nursery grounds outside of the SCB. Tags from common thresher sharks tagged in the SCB have been returned from California, USA, and Baja California, Mexico. There is also unlikely to be substantial interchange of individuals between this stock and other common thresher shark stocks because, geographically, the closest stock is likely to be along the west coast of Chile"--Executive summary

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