Gray Whales ( Eschrichtius robustus ) Off Sakhalin Island, Russia: Seasonal And Annual Patterns Of Occurrence
The annual return, seasonal occurrence, and site fidelity of Korean-Okhotsk or western gray whales on their feeding grounds off northeastern Sakhalin Island, Russia, were assessed by boat-based photo-identification studies in 1994-1998. A total of 262 pods were observed, ranging in size from 1 to 9...
| Main Authors: | , , , , , , |
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| Format: | Text |
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DigitalCommons@University of Nebraska - Lincoln
1999
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| Online Access: | https://digitalcommons.unl.edu/usdeptcommercepub/83 https://digitalcommons.unl.edu/context/usdeptcommercepub/article/1097/viewcontent/Brownell_MMS_1999_Gray_whales_off_Sakhalin.pdf |
| Summary: | The annual return, seasonal occurrence, and site fidelity of Korean-Okhotsk or western gray whales on their feeding grounds off northeastern Sakhalin Island, Russia, were assessed by boat-based photo-identification studies in 1994-1998. A total of 262 pods were observed, ranging in size from 1 to 9 whales with an overall mean of 2.0'. Sixty-nine whales were individually identified, and a majority of all whales (71.0%) were observed in multiple years. Annual sighting frequencies ranged from 1 to 18 d, with a mean of 5.4 d. The percentage of whales re-identified from previous years showed a continuous annual increase, reaching 87.0% by the end of the study. Time between first and last sighting of identified individuals within a given year was 1-85 d, with an overall mean of 40.6 d. Annual calf proportions ranged from 4.3% (1997) to 13.2% (1998), and mother-calf separations generally occurred between July and September. The seasonal site fidelity and annual return of whales to this part of the Okhotsk Sea emphasize its importance as a primary feeding ground for this endangered population. |
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