Sex ratio changes in the long-term Windermere pike and perch sampling program

Analysis of the Windermere (England), Perca fluviatilis (1965-1997) and Eso x lucius (1943-1997) fishery data indicates there have been substantial cha nges in sex ratios through time. In the case of perch, a 1976 perch disease outbreak substantially skewed the sex ratio in favor of females. It took o ver a decade for the fishery to recover to its pre-1976 state. In the case of pike, both catch and year-class data are female biased, but this bias ha s significantly weakened through time. This trend towards proportionately m ore males through time may reflect an effect of increasing spring temperatu res or an evolutionary or phenotypic response to female-biased fishing pres sure.