Chapter 7 - Reproduction, Broodstock Management, and Spawning in Captive Atlantic Bluefin Tuna

Abstract

Understanding the reproductive biology of Atlantic bluefin tuna (ABFT) is important to both managing its fishery and developing hatchery technologies to close its life cycle in aquaculture. Globally, ABFT is comprised of two populations, the eastern and western stocks, with known breeding areas in the Mediterranean Sea and the Gulf of Mexico, respectively. Gametogenesis takes place during spring and early summer, and spawning usually occurs from May to July, coinciding with the rise of water temperature. Females display an asynchronous ovarian development, typical of a batch spawner. Comparing the endocrine-reproductive cycle in wild and captive ABFT led to the development of a hormone-based therapy to induce spawning in captive broodstock. While captivity affects gametogenesis in ABFT, at least some of the captive fish spawn spontaneously, which can be enhanced and prolonged using hormonal induction. Massive spawning of captive ABFT enabled the first aquaculture production of marketable fish, demonstrating the biological feasibility of this industry. Current research on hormonal regulation of its puberty may lead to the use of smaller ABFT broodstock, simplifying their husbandry and management. This, together with the establishment of land-based broodstock operations, will enable efficient and cost-effective on-demand and year-round production of ABFT seeds to drive the consistent farming of this fish.