Age and growth of the longfin eel, <i>Anguilla mossambica</i> Peters, 1852 (Pisces: Anguillidae) in Transkei rivers

Abstract

Otoliths were successfully used for age determination and growth-rate calculation of the longfin eel, Anguilla mossambica Peters, 1852. The large opaque nucleus of the otoliths represents the leptocephalid stage and probably lasts from one and a half to two years. Thereafter, one opaque and one hyaline zone is deposited on the otoliths per year. A. mossambica in Transkei rivers have a slow growth rate and remain in fresh water for up to 18 years, during which they attain a maximum length of about 1 000 mm. The growth of the eels, ranging from 99-1004 mm total length, is isometric and is described by the equation L_t(mm) = 1390 (1-e^{−0,041 (t+0,476)}). The length/weight relationship is represented by W(g) = 7,143 x 10⁻⁴ L(cm)^3,2998, and somatic growth can be expressed by the equation W_t(g) = 8418 (1-e^{−0,041 (t+0,476)})^3,2998