Fecundity of four species of salmonid fishes in Newfoundland waters.

A total of 530 female rainbow trout, brown trout, landlocked Atlantic salmon and brook trout collected from seven ponds on the Avalon Peninsula, Newfoundland, in 1969 are included in this investigation. Except for brook trout which had a predominance of males, the sex ratios of these species were not significantly different from a 1:1 ratio. -- Females of the four species generally mature one year later than males. Landlocked salmon from Forest Pond had a higher percentage at first maturity than Ocean Pond fish of the same age. There was no marked difference in age at first maturity between Long Pond and Middle Pond brown trout. Female brook trout matured one year earlier (2+) than the other three species. While both sexes of brown trout and landlocked salmon differed in age at first maturity, they varied little in size at first maturity. -- The rates of development of the ovary in early and mid-summer are nearly constant for the four species, each decreasing one month before spawning. Landlocked salmon from both Forest Pond and Ocean Pond had the largest eggs of all fish examined. Egg size could not be consistently correlated with size and age of fish in all species. Egg numbers were significantly correlated with size and age of fish (at the 1% level} and the relationships between the variables were linear. Fecundity and weight were more closely correlated than fecundity and length. Brown trout from Middle Pond had a higher percentage of atresia than Long Pond fish. Atresia in landlocked Atlantic salmon from Forest Pond and Ocean Pond were nearly the same. Within each species the K factor of the fish was inversely correlated with atresia and positively correlated with fecundity. Fecundities of the four species in descending order are, rainbow trout, brown trout, brook trout, and landlocked salmon