Age-based life history traits of two endemic Labeobarbus species, L. tsanensis and L. platydorsus, from Lake Tana, Ethiopia

Abstract

The migratory and endemic Labeobarbus platydorsus and Labeobarbus tsanensis are threatened by extinction. This study is the first to use otolith microstructural analyses to infer life history traits of these species to assist in future conservation. We examined whole asterisci otoliths from 750 L. tsanensis and 542 L. platydorsus collected monthly between May 2016 and April 2017. The size of the L. tsanensis and L. platydorsus individuals collected was in the range 123–363- and 115–630-mm fork length respectively. For both species, 4- and 5-year-old individuals were dominant, whereas specimens older than 6 years were rarely recorded. The maximum ages recorded for L. tsanensis and L. platydorsus were 11 and 17 years respectively. Of the different growth models evaluated, the logistic growth model yielded the best fit to age-at-length data. For both species, growth parameters differed significantly between males and females, and sexual maturation proceeded faster in males than in females. Natural mortality estimates based on longevity were higher than the estimates based on growth parameters. For both species, females were predominant over males and the length–weight relationships were curvilinear. The estimated life history traits are important input parameters in further stock assessment evaluation of the species and should allow fisheries managers to optimise future conservation strategies.