Fundulus parvipinnis in Mission Bay: Understanding Patterns of Fecundity and Reproduction

The California killifish (Fundulus parvipinnis) is a ubiquitous species in Southern California marsh habitats, yet there is limited knowledge of their reproductive biology, with our current understanding largely derived from a few natural history notes and studies of congeners found along the Atlantic coast. This study examined the reproductive patterns of F. parvipinnis, and their fecundity, measured in terms of gonadal weight and oocyte density. To assess fecundity, gonadal tissue of female F. parvipinnis individuals was extracted, weighed, and oocytes counted. Additionally, the diameter of a subset of oocytes from each individual was measured to determine their stage. Reproductive patterns of F. parvipinnis were assessed by measuring and weighing individuals collected in the field and then calculating changes in length/weight ratio through time as an indication of reproductive activity. In doing so, potential correlations between reproduction and lunar cycles were determined. Preliminary results show that on average ovary wet weight was 6.7% of body weight, and this changed through time with lunar cycles. Immediately following the spring tide, the average ovary weight was 5.1% of the average body weight, whereas immediately prior to the spring tide it was 11.4%. Furthermore, preliminary analysis suggests that F. parvipinnis individuals prepare for spawning on a lunar cycle.