Integrating the effects of fish exploitation and interspecific competition into current life history theories; an example with lacustrine brook trout (Salvelinus fontinalis) populations

摘要

We used data from 17 populations of lacustrine brook trout (Salvelinus fontinalis) of the Canadian Shield, southern Quebec, to test whether early maturity (in males and females) and high reproductive effort (in females) are associated with increased (i) fish exploitation (sportfishing) and (ii) interspecific competition through their effects on growth and survival. The age at maturity of males and females was inversely related to the intensity of both fishing and interspecific competition. Fishing and interspecific competition affect the age at maturity through their effect on adult survival but not on growth, supporting predictions of life history models based on survival. In contrast, we did not find consistent effects of interspecific competitionand fishing on the gonadosomatic index of females, which was directly related to survival (in all populations) and to the age at maturity (in exploited populations). These latter results are contrary to the predictions of life history models under the assumption that survival is directly related to growth rate. Our results suggest that reproductive effort and age at maturity are not dependent on growth when survival is independent of growth, as is the case in exploited and sympatric populations experiencing low adult survival but high growth.