[MARMAM] New paper: gray whale offshore migratory corridors

Jim jim.sumich at gcccd.edu
Sun Jun 19 12:23:18 PDT 2011


> A new paper is now available:
> Sumich, J.L., and Show, I.T. 2011. Offshore migratory morridors and aerial
> photogrammetric body length comparisons of southbound gray whales,
> Eschrichtius robustus, in the southern California Bight, 1988-1990. Marine
> Fisheries Review 73: 28-34.
>  
> Abstract:
> Through most of their annual migration, gray whales, Eschrichtius robustus,
> remain within 10 km of shore, but in the Southern California Bight many
> individuals migrate much farther from shore. This paper summarizes aerial
> survey and photogrammetric efforts to determine body lengths and temporal and
> spatial distributions of migratory gray whales in the southern portion of the
> Southern California Bight. Aerial surveys were flown along 13 east–west
> transects between lat. 32°35′N and 33°30′N during the southbound gray whale
> migratory seasons of 1988–90 in the Southern California Bight. Photogrammetry
> was used to obtain body length estimates of animals during some of the
> surveys. A total of 1,878 whales in 675 groups were sighted along 25,440 km of
> transect distance flown and 217 body lengths were measured. Using position and
> heading data, three major migratory pathways or corridors in the southern
> portion of the bight are defined. Those migrating offshore were split almost
> evenly between two corridors along the west sides of Santa Catalina and San
> Clemente Islands. These corridors converge on the mainland coast between San
> Diego and the United States–Mexico border. No whales larger than 11.5 m were
> photographed within 30 km of the mainland coast, suggesting that smaller, and
> presumably younger, whales use the coastal migratory corridor through the
> California Bight.
> 
> A PDF can be downloaded from: http://spo.nmfs.noaa.gov/mfr731/mfr7313.pdf
>  
> Jim Sumich

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