Skipped Spawning or Partial Migration?

Borrowing from avian ecology, partial migration can accommodate a large range of reproductive migration behaviors into classes of partial migration, including classic mixed populations of resident and migratory contingents, straying, irruptions, differential migration, and skipped spawning.    These categories of behavior have been linked to myriad causes, including food availability, competition, sexual and resource polymorphisms, mating opportunities, sexual harassment, increased swimming performance and roaming with size, increased tolerance of suboptimal environmental conditions with size, changed reproductive investments with size, exposure to novel food webs and ecosystems, catastrophic ecosystem changes, threshold changes in food webs and ecosystems, wholesale physical evacuations, land-locking, and navigation and physical transport related to vertical ranging behaviors.  These explanations overlap broadly, causing partial migration and skipped spawning to be adjusted, altered, interrupted, amplified, and stabilized in countless ways as groups of fish respond conditionally to their ecological and social circumstances.  Although it will be complex to mechanistically model skipped spawning, its consequences to fisheries assessments can be evaluated through simulated scenarios on the effect of mis-specified reproductive schedules on stock performance.