Atlantic bluefin tuna (ABT), Thunnus thynnus, spawn in the Gulf of Mexico (GoM) and the Mediterranean Sea (MED). Spawning occurs within narrow temporal and environmental parameters. Efforts to characterize growth of ABT in wild conditions revealed a wide range of growth variability during the early life stages. This series of studies examined potential biotic and abiotic influences of larval growth from seven ABT cohorts, and identified several key drivers of growth for this commercially valuable species. A detailed investigation of larval dynamics using otolith microstructure was conducted as follows. First, companion growth curves and stable isotope analysis from the same spawning season (2014) in the GoM and MED revealed distinct growth strategies. GoM larvae grew faster, had larger otoliths, and had wider increments associated with lower δ15N than the MED. Second, food limitation and feeding preferences explained the most variance of recent growth between two larval patches in the GoM. While mean growth rates were similar, one nursery habitat appeared better suited for faster preflexion growth, while the other had faster flexion to postflexion growth likely attributed to abundant of preferred prey (copepod-nauplii, cladocerans). Lastly, inter-annual growth from historical SEAMAP collections (2015-2017) in the GoM revealed similar growth rates between years and that among the mesoscale oceanographic features sampled, Common Water was highly suitable habitat for ABT growth. Fisheries-independent surveys targeting ABT provide larval abundances for assessments of adult spawning stock biomass. Ecological studies such as these, that incorporate environmental parameters, and integrate standardized abundance estimates, will improve current models utilized in ABT management.
| Date of Award | Dec 6 2022 |
|---|
| Original language | English |
|---|
| Supervisor | Tracey Sutton (Supervisor), David Kerstetter (Advisor), Trika Gerard (Advisor), Raúl Laiz-Carrión (Advisor) & John T. Lamkin (Advisor) |
|---|