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

A mismatch between male and female gamete release can result in reduced or failed fertilization in external fertilizers, sperm competition and reduced paternity. Here, I video monitored spawning behavior of free living Arctic charr (Salvelinus alpinus), and analyzed details of their reproductive biology. In total, 157 spawnings were recorded. Females clearly preferred spawning with the dominant male, and even under sperm competition a high level of synchrony in timing of gametes released was observed. Although the average sneaker released his milt 0.6 seconds after the spawning female, sneakers spawned with higher synchrony than the dominant male in single male spawning event. Approximately 50% of the recorded spawning events occurred under sperm competition, where each event included an average of 2.7 males. Sneakers were more exposed to sperm competition than dominant males. An influx of males in close proximity to the female occurs during the behavioral sequences leading up to egg release, but this influx seems not dependent on egg release (i.e., in situations of “near” spawnings). This suggests that there is something other than gonadal product that attract males to the spawning female. I suggest that vibrational communication between the spawning couple reveals time of gamete release to surrounding males. This might explain the relative high level of synchrony observed in both male tactics, yet, vibrational communication comes with the cost of higher detectability from surrounding males. Throughout this study, mate guarding seems to be the prevailing factor for paternity in Arctic charr. Mate guarding effect accessibility to females, sperm competition, synchrony of gamete release and subsequent egg predation.