Contrasting life-history strategies facilitated by cannibalism in a stunted Arctic charr population

Life-history tradeoffs between energy investments in reproduction versus somatic growth may be highly important for fish populations suffering from food limitations. This study addresses life-history tradeoffs in a stunted Arctic charr population from a subarctic lake sampled annually over a 12-year period. The vast majority of charr matured early, grew slowly toward average adult sizes of 13-14 cm, and had a short longevity with few fish reaching ages older than 6 years. Some gender differences in life-history strategies related to sexual maturation were revealed, likely due to energetic constraints from high cost of egg production. Some charr followed a highly different growth trajectory, growing rapidly and attaining lengths > 40 cm. These fast-growing individuals matured later and reached higher ages than the stunted fish. Hence, there was a distinct tradeoff between early versus late sexual maturation, the former strategy resulting in short generation time enhancing the survival up to first spawning and the latter being related to a dietary shift to cannibalism resulting in increased growth and body size, and reproduction at a postponed maturation age. This dual pattern was sustained over the 12-year study period, apparently reflecting two contrasting stable strategies.