CARLINE: PRODUCTION BY WILD BROOK TROUT 



TABLE 5. — Instantaneous total mortality rates for 182-day intervals. Mortality rates of trout in 

 Maxwell Springs were calculated from year class densities. Mortality rates of trout in Hoglot 

 and Clubhouse springs were calculated from permanently marked fish. Estimated numbers of 

 trout at the end of sampling intervals given in parentheses. 



'Age at start of interval. 



TABLE 6. — Estimated numbers of immigrant brook trout present by age-groups at the end of 

 sampling intervals. Summer intervals were from April to September and winter intervals from 

 September to the following April. Percent of population at the end of the interval composed 

 of recently immigrated trout given in parentheses. 



During this 4-yr period over 9,700 age 1 and older 

 trout immigrated into the pond, hence, migrants 

 accounted for about 70% of total recruitment of 

 yearling and older trout. 



It is likely that trout migrating from Elton 

 Creek into Clubhouse Springs were smaller than 

 pond residents because: 1) trout in Elton Creek 

 grew more slowly than those in Clubhouse 

 Springs and 2) permanently marked trout in the 

 pond, i.e. residents, were larger than unmarked 

 trout, which were mostly recent immigrants. 

 From 1968 to 1970 fall fingerlings in Elton Creek 

 averaged 4.2 g and those in Clubhouse Springs 

 were 9.6 g. Fall yearlings in Elton Creek averaged 

 30 g and yearlings in the pond were 46 g. In spring 



and fall, marked yearlings in Clubhouse Springs 

 were about 20% heavier than unmarked year- 

 lings. For age 2 trout in spring, marked trout 

 were 58% larger than unmarked ones. I made 

 similar comparisons for ages 1 and 2 trout in 

 Hoglot Springs; differences in sizes among 

 marked and unmarked trout were not consistent 

 and I concluded that migrants were similar in 

 size to pond residents. 



Growth 



Among populations, mean size attained by trout 

 of a given age was greatest in Clubhouse Springs 

 (Table 7). After the first full year of life trout in 



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