Blue marlin (Makaira nigricans) longevity estimates confirmed with 

bomb radiocarbon dating

ABSTRACT: The longevity of blue marlin (Makaira nigricans) remains unresolved. The use of fin spines and sagittal otoliths for age reading has led to unconfirmed longevity estimates near 20–30 years. Age validation has been elusive because large individuals are uncommonly caught, and a technique that can be applied to structures that provide estimates of age was absent. The use of otolith chemical signatures has been limited by sagittal otoliths that are very small — whole otolith mass of adult blue marlin rarely exceeds 10 mg for the largest fish. Recent advances in the detection limits of radiocarbon (14C) with accelerator mass spectrometry — coupled with recently acquired knowledge of marine bomb14C signals spanning the tropical Pacific Ocean — have led to an opportunity to age blue marlin from small amounts of otolith material. In this study, otoliths from a recently collected 1245 lb. (565 kg) female blue marlin at a measured 146-inch (371 cm) lower jaw fork length were analyzed for14C. Estimated longevity was either 12–21 or 32–44 years on the basis of bomb14C dating. Using multiple lines of evidence, it was determined that the young age scenario was most likely, with evidence for an age close to 20 years using a series of deductions in the bomb14C dating method. 

Published CJFAS: https://doi.org/10.1139/cjfas-2017-0031

PROJECT BACKGROUND

Photograph above is of the grander blue marlin (Makaira nigricans) at time of capture 21 miles (34 km) south of Honolulu, Oahu, Hawaii on 1 September 2009. Inset are the small sagittal otoliths extracted by J.D. Sampaga from the specimen and pictured with the edge of a US dime for scale. Marvin Bethune (tired fisherman pictured with fish) and the crew of the F/V Maggie Joe out of Honolulu landed the 1245 lb. (565 kg) fish and made the head available for science. Without their foresight and the capable hands of those involved with collecting and keeping the otoliths, this work would not have been possible.