Age and growth of the Mesopotamian spiny eel, Mastacembelus mastacembelus (Banks & Solender, 1794), from southeastern Anatolia

Abstract

Mesopotamian spiny eels, Mastacembelus mastacembelus (Banks & Solender, 1794), were collected from a large dam lake located on the Euphrates River in order to determine the most reliable ageing method among different hard structures and to estimate growth parameters. Vertebra, otolith, and opercle series were removed from 195 individuals. Vertebrae displayed the most interpretable annulus formations. Total length ranged from 14.4 cm to 76.9 cm and total weight ranged from 6.0 g to 950.0 g. The length and weight frequency distribution was significantly different between the 2 sexes (K-S test, P < 0.001). The length-weight relationship, determined as W = 0.004TL(2.84) (r = 0.98), revealed no sex-based significant difference (GLM, P > 0.05). Age classes ranged from 1 to 21 years in males and up to 9 years in females. Vertebra diameter was strongly correlated with total length and age, which were expressed by linear or cubic regression equations. The von Bertalanffy growth parameters were L infinity = 81.7 cm, k = 0.13 cm year(-1) and t(0) = -0.573 years for the combined sexes, and the empty set_' index was estimated as 6.766. Age interpretation revealed that a natural mark occurs on vertebrae in the third year of growth. This mark was composed of narrowly arranged numerous checks within the third annulus and it disappeared in subsequent annuli, which may be related to an environmental stress factor that occurred in that year.