Abundance, range and movements of a feeding aggregation of gray whales (Eschrichtius robustus) from California to southeastern Alaska in 1998

摘要: This study documents the range, abundance and movements of a feeding aggregation gray whales ( Eschrichtius robustus) in Pacific northwest. Identification photographs were collected by eight collaborating organisations between March November 1998. Surv eys extended northern California southeastern Alaska. Effort was variable region concentrated off northe rn Washington coast Vancouver Island. Of 1,242 occasions when suitable obtained 1998, 155 u nique identified. Each individual photographed an average 8.0 times (SD = 8.4, range 1-42) tenure seen multiple 56 days 41, 1-170). Whales longer than three months generally regi ons. Movements among regions 1998 documented for 57 with most frequent interchange adjacent areas fro m to central The overall pattern complex; not al ways moving same direction at time year. within more distant locations did occur but le ss frequently observed. Total distances resighting positions ranged from < 1 526 n.miles. Most wha les had been identified previous years compared some collaborators. At least 86 (55%) previously. rate inter-year resightings highest identifie d British Columbia (from southern Island north Island). In these areas, 70-100% each Mark-recapture estimates based on compari sons samples 1996 1997 181 179, respectively. management implication has become controversia l due resumption whaling Makah tribe Washington, area used both migrating whales. research shows that there are few hundred summer Al aska. mechanism which animals recruited into this group degree they should be managed as separate uni t population is resolved.