The Size–Age Structure, Growth, and Maturation of the Spotted Catfish Arius maculatus (Thunberg, 1792) (Siluriformes: Ariidae) from the Mekong Delta, Vietnam

Abstract

The size–age structure, growth, and maturation of the spotted catfish Arius maculatus (Thunberg, 1792) from the Hau River estuary, Mekong Delta, Vietnam, were studied for the first time. A total of 460 fish specimens collected from January to March 2019 were examined. The annuli on the otoliths were visualized; their formation may be related with the alternation of the dry and rainy seasons. The male to female ratio in the catches was 1 : 1.81. The proportion of males decreased in the older age groups. The maximum total body length of the females was 21.9 cm; for the males, it was 23.7 cm. The maximum recorded age of females in catches was 7+; for males it was 8+. No inter-gender differences in growth were detected. The parameters of the von Bertalanffy equation for both sexes according to empirical data were as follows: L∞ = 28.3 cm; k = 0.15/yr; t0 = –1.03 yr; growth performance index, φ = 2.08. The coefficients of the relationship between mass and length were as follows: a = 0.0054; b = 3.22. Maturation began at a body length of 13 cm at an age of 3 yr and ended at a body length of 18 cm at an age of 6 yr; 50% of the individuals became mature at a body length of 15 cm at an age of 4 yr. No inter-gender differences in the timing of maturation were found. A. maculatus from the Mekong Delta is characterized by a low growth rate compared to other populations, which may be associated with the labile habitat conditions in the estuary zone.