Intermittent breeding in the absence of a large cost of reproduction: evidence for a non‐migratory, iteroparous salmonid

Abstract

In long‐lived organisms, intermittent breeding likely evolves as a resource allocation strategy for coping with environmental uncertainty or individual heterogeneity in condition. In fishes, the phenomenon of intermittent breeding is referred to as skipped spawning, and appears to be more common at high latitudes or in migratory species with high accessory costs of reproduction. We used long‐term monitoring data on lake trout (Salvelinus namaycush) to test whether key predictions about the frequency of skipped spawning hold in a mid‐latitude population of a species lacking any obvious costs of reproduction beyond the production and fertilization of gametes. We first developed a threshold‐based method to classify skipped spawners based on gonad size, fish size, and fish age. Consistent with life history theory, age‐specific frequencies of skipped spawning were higher in females than males. The frequency of skipped spawning varied among years and was higher in 1994–2011 than in 1938–1959, perhaps because of food web changes over the past century. In temperate lakes, food web structure may be sufficiently variable to favor intermittent breeding in long‐lived iteroparous fishes, despite low accessory costs of reproduction.