Spawning behaviour of Arctic charr (Salvelinus alpinus): spawning synchrony, vibrational communication and mate guarding

A mismatch between male and female gamete release in external fertilizers can result in reduced or failed fertilization, sperm competition and reduced paternity. Here, spawning behaviour of free-living Arctic charr (Salvelinus alpinus) was video recorded, and their reproductive behaviour was analysed. From evaluating 157 spawning events we observed that females mainly spawned with a guarding male and the female and the guarding male synchronized timing of gamete releaseunder sperm competition. Although sneakers spawned with higher synchrony than the guarding male in single male spawning events, the average sneaker released his milt 0.6 seconds after the spawning female under sperm competition. Approximately 50% of the recorded spawning events occurred under sperm competition, where each event included an average of 2.7 males. Additionally, sneakers were more exposed to sperm competition than guarding males. An influx of males, in close proximity to the female, occurred during the behavi...