Assessing Growth of Tropical Tuna Species

February 11, 2022

Principal Investigators: Lynn Waterhouse and John M. Hoenig (Virginia Institute of Marine Sciences)
Funding: Atlantic Ocean Tuna Tagging Programme (AOTTP) through International Commission for the Conservation of Atlantic Tunas (ICCAT). 
Collaborators: University of Minnesota Department of Fisheries, Wildlife, and Conservation Biology; John G. Shedd Aquarium; Virginia Institute of Marine Sciences at The College of William and Mary; Atlantic Ocean Tuna Tagging Programme (AOTTP); International Commission for the Conservation of Atlantic Tunas (ICCAT); National Marine Fisheries Service (NMFS); Departamento de Ciências Animais, Universidade Federal Rural do Semiárido, Brazil; The University of Maine – Gulf of Maine Research Institute; University of Hawaii at Manoa, Department of Oceanography; Institute fondamental Afrique noire Cheikh Anto Diop - Corniche Ouest - Université Cheikh, Senegal; Fish Ageing Services, Australia.

The International Commission for the Conservation of Atlantic Tunas (ICCAT) concluded the Atlantic Ocean Tropical Tuna Tagging Programme (AOTTP) in 2021. The ICCAT AOTTP project had the objectives of enhancing food security, stimulating economic growth, and improving management through research on tuna resources in the Atlantic Ocean. This work is based on a contract (N4001546C) to study the growth of three tropical tuna species – Bigeye, Skipjack, and Yellowfin tuna utilizing data collected by the AOTTP including tag recaptures and hard part data (otolith and spine). The project has resulted in two peer-reviewed publications (accepted with revisions) in Fisheries Research one on a methodological development entitled “Imputation of missing growth rings in fish spines, with application to skipjack tuna (Katsuwonus pelamis) age and growth” and the other an assessment of Bigeye tuna growth entitled “Updated Growth Models for Bigeye Tuna (Thunnus obesus) in the Atlantic Ocean”. Two additional papers are being prepared – one focusing on growth models for Yellowfin tuna and the other will be a proper Bayesian model for estimating the number of missing rings from obliterated spines. Some fish can be aged using rings in spines (similar to how otoliths are used) – but for some species the center of the spine becomes vascularized as they age – obliterating the central rings. Spines are often easier (and more favorable) to sample compared to otoliths as they do not involve killing the fish and they may leave the fish in better condition for market sale. Thus, the ability to use spines, that have obliterated centers to accurately estimate ages, could be widely used in assessing various fisheries. The phenomena of obliterated spines occurs in both freshwater and marine species.