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Sexual Maturity and Fecundity in Brown Trout of the Platte River, Michigan
Author(s) -
Taube Clarence M.
Publication year - 1976
Publication title -
transactions of the american fisheries society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.696
H-Index - 86
eISSN - 1548-8659
pISSN - 0002-8487
DOI - 10.1577/1548-8659(1976)105<529:smafib>2.0.co;2
Subject(s) - fecundity , sexual maturity , fishery , maturity (psychological) , biology , trout , fish <actinopterygii> , ecology , demography , population , psychology , sociology , developmental psychology
Sexual maturity in brown trout (Salmo trutta) of the Platte River begins in males when they are between 177 and 202 mm in length, and in females essentially when they are between 202 and 228 mm. At these sizes, incidence of maturity in the two sexes is the same, 35%. At age I, 32% of the males and 16% of the females are mature. Incidence is virtually 100% in males when they reach 253 mm or age III, and 100% in females at 304 mm or age IV. In the length range of 202–354 mm, the average number of eggs produced per female trout ranges from 241 to 936. The largest number found among 89 fish (202–472 mm) was 2,419. Although fecundity varies widely between individuals of similar size and identical age, it is, as a whole, positively correlated with both size and age. The formula for regression of egg number, N, on the length is: N = 7.3 (total length, mm) ‐ 1,498.8. The formula for egg number by age is: N = 353.3 (age group) ‐ 155.7. Size of eggs also varies considerably between individual fish, but like fecundity, it is correlated with size and age of females; that is, the larger and older females produce the larger eggs. Average diameter of eggs from brown trout collected in September ranged from 3.2 to 4.8 mm among individual fish that were from 193 to 472 mm in length.