Yield, growth and mortality rate of the Thai river sprat, Clupeichthys aesarnensis, in Sirinthorn Reservoir, Thailand

The Thai river sprat, Clupeichthys aesarnensis Wongratana, is a clupeid with a short life span, and supports artisanal fisheries in a number of reservoirs in the Mekong Basin. The growth parameters, mortality rates and the status of the Thai river sprat in Sirinthorn Reservoir (28 800 ha), NE Thailand (15&deg;N; 105&deg;E), are presented. The fishery is based on lured lift-nets, operated 7&ndash;14 days in the new moon period, September to April each year. It was shown that the von Bertalanffy growth function (VBGF) model was Lt (mm) = 78.43[1 &minus; exp{&minus;0.211[t &minus; (&minus;0.7996)]}] and its growth conformed to an isometric pattern. Natural mortality rate (month&minus;1) was 0.13 month&minus;1. Total mortality rates ranged from 0.69 to 1.53 month&minus;1 depending on the weather and the fishing season. Recruitment was continuous throughout the year but peaked in June and July. The yield per recruit model indicated that the exploitation rate of this fishery is probably too high.<br /

Fish biodiversity research in the Mekong Basin

The Mekong River is one of the great rivers of the world and is characterized by high fish biodiversity (Valbo-Jorgensen et al. 2009). The Mekong region is in fact a fish biodiversity hotspot whose richness is only now being revealed. During the last decade more than 279 new species of fish have been discovered in this basin alone (WWF 2009). An analysis of fish species present in 204 rivers worldwide recorded in FishBase (www.fishbase.org) (Fig. 1) and backed by a scientific study or publication. Baran (2010) recently showed that the Mekong River is the second richest river in the world for its fish diversity, after the Amazon River