Pelagic Fishes
Yellowfin and Bigeye Tuna Longevity
CJFAS - Published January 2020
Age validation and potential lifespan of yellowfin
(Thunnus albacares) and bigeye (Thunnus obesus) tuna of the northwestern Atlantic Ocean
Allen H. Andrews1, Ashley Pacicco2, Robert Allman2, Brett J. Falterman3, Erik T. Lang3, & Walter Golet4
1. University of Hawaii, Department of Oceanography
2. Louisiana Department of Wildlife and Fisheries
3. National Marine Fisheries Service, Southeast Fisheries Science Center, Panama City Laboratory
4. The University of Maine - Gulf of Maine Research Institute, School of Marine Sciences
Estimates of age and growth for yellowfin (Thunnus albacares) and bigeye (Thunnus obesus) tuna remain problematic because validation of growth zone deposition (opaque and transparent) hasn't been properly evaluated. Otolith growth structure (zone clarity) can be poorly defined for tropical tunas but the use of bomb radiocarbon dating has validated age estimates to 16–18 years for yellowfin and bigeye tuna. Use of the radiocarbon decline period — defined by regional coral and otoliths — provided valid ages through ontogeny. Yellowfin tuna aged 2–18 years (n = 34, 1029–1810 mm FL) and bigeye tuna aged 3–17 years (n = 12, 1280–1750 mm FL) led to birth years that were coincident with the bomb radiocarbon decline. The results indicate there was no age reading bias for yellowfin tuna and that age estimates of previous studies were likely underestimated for both species.
Fig. 1. Yellowfin (Thunnus albacares) and bigeye (T. obesus) tuna otolith sections viewed with transmitted light for the oldest specimens YFT-C32 (A) and BET-C03 (B). The age reading protocol was defined by growth zone structure that has some level of subjectivity (typically ±1 year), but overall the counts were 18 years for YFT-C32 and 17 years for BET-C03. Age reading out to 5 years appeared as broad, diffuse bands that traverse the section and can be used as a tool for lumping the subannual growth structure of early growth. Finer zone structure begins after a bend in the growth axis and can be difficult to resolve (inset images). Age reading for each species was delineated along the ventral arm as shown and enumerated here and was consistent with the age reading protocol presented in recent studies of each species (Lang et al. 2017; Farley et al. 2017).
Fig. 2. Aged yellowfin tuna (Thunnus albacares) that were cored (sampled within first year of growth) and measured for 14C are plotted relative to the Loess curve that was used to describe the central tendency of the entire bomb 14C reference record for the Gulf of Mexico (coral and otolith records with known dates of formation; Andrews et al. 2013; Barnett et al. 2018), including yearling YFT. The 14C values for YFT are plotted at the collection date (x-symbol) and then as a projected birth year based on age from otolith growth zone counting (estimated 2–18 years). Note that a correlation of otolith values to the 14C rise (1950s to 1960s) is possible but would lead to unreasonable ages on the order of 40–50 years and an unrealistic age-at-length structure through ontogeny.
The full findings of this study are available from Canadian Journal of Fisheries and Aquatic Sciences as a Rapid Communication. dx.doi.org/10.1139/cjfas-2019-0328
Life history information for these species needs to be updated:
https://www.fisheries.noaa.gov/species/atlantic-yellowfin-tuna
