Demographic and life-history responses of an over-exploited bull trout (Salvelinus confluentus) population to zero harvest regulations.

Abstract

The study of an over-exploited bull trout (Salvelinus confluentus) population after the introduction of zero harvest regulations, demonstrated the ability of this population to recover from overharvest. Adult abundance increased 25 fold over a decade and approached a carrying capacity, providing an opportunity to characterize the demographics and life history traits of a threatened species. Density-dependent changes in survival, growth, maturation and spawning frequency were observed. Density-dependent survival of juvenile bull trout prior to age-1 was found to be the primary factor limiting further population growth. However, density-dependent adult survival and changes in maturation and fecundity may also have influenced population dynamics. Density-dependent changes in life history characteristics also provided insight into how energetic tradeoffs between growth and reproduction differ between the genders. The importance of all life stages in the management of species with complex life histories was demonstrated in this study.