Baker et al : Population characteristics of Megaptera novaeangliae in southeastern Alaska 



433 



between high and low years from 1981 to 1986, a Test 

 of Independence indicated that these year-to-year dif- 

 ferences were not significant (x" [6] 6.88, p 0.332). 

 Average calving rate across the 7-year study was 0.36 

 calves/year (95% binomial CL: 0.284-0.432), similar to 

 the previously reported rate of 0.37 for the years 

 1980-85 (Baker et al. 1987). 



Local abundance and interchange 



Capture-recapture estimates of seasonal abundance for 

 the Glacier Bay and Frederick Sound subregions were 

 calculated using the Petersen formula with Bailey's cor- 

 rection and treating each survey or survey period as 

 a sample (Tables 4 and 5). In Glacier Bay, the number 

 of individual whales identified was greatest during June 

 and July and declined through August and September 



(Table 4). The percentage of newly-identified whales 

 declined rapidly through the summer, suggesting that 

 the census of identified individuals approached a com- 

 plete count of the whales in this subregion. Capture- 

 recapture estimates based on monthly censuses ranged 

 from 18 to 42 and agreed closely with the total number 

 of 40 adults identified in this subregion. 



In Frederick Sound, the number of individual whales 

 identified during each survey remained constant from 

 late July to mid-September and declined by late fall 

 (Table 5). The percentage of newly-identified whales 

 decreased through the three summer surveys but in- 

 creased in the late-fall survey. The Frederick Sound 

 capture-recapture estimates from the three summer 

 surveys ranged from 211 to 247, exceeding the total 

 of 158 individuals identified during this period but not 

 approaching the between-year estimates of regional 

 abundance (see Table 1). Capture-recapture estimates 

 increased considerably when summer surveys were 

 compared with the fall surveys. Ranging from 283 to 

 704, the fall estimates agreed more closely with across- 

 year estimates for the entire southeastern Alaska 

 region. The larger capture-recapture estimates from 

 the fall survey and the increase in percentage of new- 

 ly identified whales suggested the dissolution of popula- 

 tion stratification observed during the summer months 

 or the arrival of individuals from unsurveyed areas of 

 southeastern Alaska. 



Documented interchange between the southeastern 

 Alaska subregions was limited to 12 transits by 10 in- 

 dividual whales (Table 6). Eight one-way transits were 

 from Glacier Bay to Frederick Sound, and a single one- 

 way transit was from Frederick Sound to Glacier Bay. 

 One individual, animal #616, traveled from Glacier 



