Bangana behri tropical fish

This fish occurs in the Mekong basin in Cambodia, Thailand, Lao PDR and Yunnan province, China. Its populations are being impacted by commercial fisheries in some parts of its range, and heavy fishing pressure has caused a past decline of approximately 30–50% over the last 21 years. A significant future threat is from the development of the mainstream dams on the Mekong which will impact upon the long distance migration of the species.

The scope of the impact is uncertain because (i) the timing and number of mainstream dams is uncertain, and (ii) further information is needed on the ecology of the species in order to understand the impacts from the dams. However, it is clear that the dams (there are an estimated eleven mainstream dams proposed within the range of this species) will have a significant impact on the species in terms of reproductive success and recruitment.

It is estimated that the population of the species will be compartmentalised by the dams, though it is possible that the species may be able to reproduce where flowing water is still present (S. Kullander, pers. comm.).

The species is assessed as Vulnerable, with a precautionary assumption of a population reduction of ca. 30% across its range. Detailed research is needed to gain a better understanding of the ecology of this species and the impact on migrations of dam construction. The species may be reassessed under a higher category if information becomes available to confirm the negative impacts of dam construction on the population.

Geographic Range

Range Description: This species occurs in the Mekong basin. It is recorded in Cambodia north of Kratie, in Thailand (including, as its synonym, Osteochilus tatumi Fowler, 1937, from the Chao Phraya River in Thailand at least as far north as Chiang Mai), Lao PDR, Viet Nam (in Srepok) and Yunnan province, China.

Population

This is an abundant species throughout its range. However a population decline of approximately 30-50% is inferred due to heavy fishing pressure. It is expected to continue decline in the future at this rate or higher, as proposed dam constructions within its range will have a significant and immediate impact on migrations (Baird and Flaherty 2004; Baird 2009a, 2009b).

Current Population Trend:DecreasingAdditional data:

Habitat and Ecology

This species is found in large rivers and streams. In the Mekong basin, the juveniles migrate out of the Sesan, Srepok and Srepok (the 3S) rivers into the mainstream Mekong, turn downstream to the border of Kratie and Stung Treng Province, and then turn upstream to southern Laos PDR and northeastern Thailand for feeding purposes. They graze on algae on rocks (Baird and Flaherty 2004). The species spawns in the middle of the Sekong River in July and August. The maximum size recorded is 60 cm (Sokheng 1999).

Systems: FreshwaterGeneration Length (years):10Movement patterns:Full Migrant