Spawning periods represent critical times for production and vulnerable times for harvesting of fish stocks and it is important to understand their causal basis. This research project explores a new hypothesis in order to explain the patterns of mating in pelagically-spawning marine fishes: the hypothesis is that, spawning sites and times are selected in order to improve fertilization success rates. Previous studies have shown that for the bluehead wrasse, Thalassoma bifasciatum, the timing of mating varies dramatically between local populations, that mean fertilization rates are surprisingly low and appeared to be influenced by turbulence and location on the reef, and that the number of sperm released by males correlates significantly with the size and fecundity of the female with whom they are mating. This project will undertake three interrelated investigations on: 1. the timing of mating, 2. the location of mating, and 3. fertilization success.
