Reproductive physiology of bonefishes (Albula spp.) across the Northwest Bahamas

Bonefishes (Albula spp.) are classified within the superorder Elopomorpha, which is comprised of over 1000 species that share a unique leptocephalus larval stage. Bonefishes have a circum-tropical distribution, inhabiting inshore shallow water flats and gathering in presumptive nearshore pre-spawn aggregations (PSA) during spawning months. These fishes support economically important recreational fisheries and subsistence fisheries throughout their ranges, yet little is known regarding their reproductive biology. Analysis of oocyte development and nutrient composition, and sex and gonadotrophic hormone levels, was conducted on females sampled in Grand Bahama, Central Andros, and South Andros, The Bahamas, to assess their reproductive state. Fish collected from the flats habitats along all three islands exhibited four major reproductive phases (immature, developing, spawning capable, and regressing). In contrast, all females captured at presumptive PSA sites had eggs in the final stage of oocyte maturation, significantly higher levels of all reproductive hormones (17β-estradiol, testosterone, and LH), larger vitellogenic oocytes, and oocytes exhibiting germinal vesicle migration and germinal vesicle breakdown. In addition, monthly variability in hormone levels and spawning readiness between Grand Bahama and Andros PSAs suggest that peak spawning times may differ among regions. Fatty acid and free amino acid composition and profiles, with high proportions of docosahexaenoic acid, histidine, and taurine, suggest that these nutrients are not only relevant as energy reserves, but also help achieve buoyancy and osmoregulation of oocytes. This study expands upon our understanding of fish reproductive and developmental physiology, and indicates potential factors influencing the survival and recruitment of bonefishes.