New scale analyses reveal centenarian African coelacanths

Type Article
Date 2021-08
Language English
Author(s) Mahé KeligORCID1, Ernande BrunoORCID2, 3, Herbin Marc4
Affiliation(s) 1 : IFREMER, Fisheries Laboratory, Boulogne sur mer, France
2 : MARBEC, Univ. Montpellier, IFREMER, CNRS, IRD, Montpellier, France
3 : Evolution and Ecology Program, International Institute for Applied Systems Analysis (IIASA), Laxenburg, Austria
4 : Mécanismes Adaptatifs et Evolution (MECADEV, UMR7179), Muséum National d’Histoire Naturelle de Paris, CNRS, Paris, France
Source Current Biology (0960-9822) (Elsevier BV), 2021-08 , Vol. 31 , N. 16 , P. 3621-3628.e4
DOI 10.1016/j.cub.2021.05.054
WOS© Times Cited 5
Abstract

The extant coelacanth was discovered in 1938;1 its biology and ecology remain poorly known due to the low number of specimens collected. Only two previous studies1,2 have attempted to determine its age and growth. They suggested a maximum lifespan of 20 years, placing the coelacanth among the fastest growing marine fish. These findings are at odds with the coelacanth’s other known biological features including low oxygen-extraction capacity, slow metabolism, ovoviviparity, and low fecundity, typical of fish with slow life histories and slow growth. In this study, we use polarized light microscopy to study growth on scales based on a large sample of 27 specimens. Our results demonstrate for the first time nearly imperceptible annual calcified structures (circuli) on the scales and show that maximal age of the coelacanth was underestimated by a factor of 5. Our validation method suggests that circuli are indeed annual, thus supporting that the coelacanth is among the longest-living fish species, its lifespan being probably around 100 years. Like deep-sea sharks with a reduced metabolism, the coelacanth has among the slowest growth for its size. Further reappraisals of age at first sexual maturity (in the range 40 to 69 years old) and gestation duration (of around 5 years) show that the living coelacanth has one of the slowest life histories of all marine fish and possibly the longest gestation. As long-lived species with slow life histories are extremely vulnerable to natural and anthropogenic perturbations, our results suggest that coelacanths may be more threatened than previously considered.

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