Emulating the natural spawning conditions of Labeobarbus brevicephalus (PISCES: Cyprinidae) from Lake Tana, Ethiopia

Abstract

Labeobarbus brevicephalus is one of the 17 endemic migratory large African barb species making up a species flock in Lake Tana (Ethiopia). The multiple constructions of dams and irrigation weirs on the tributary rivers of Lake Tana have become detrimental to the upstream spawning migration of these fishes. Considering worst-case scenarios of obstruction of all-natural migratory routes, artificial spawning emulation structures were designed and developed at the Bahir Dar Fisheries and Other Aquatic Life Research Center (BFALRC) to emulate the upstream spawning migration routes and habitats. A pond was constructed to emulate the lake and a canal was connected to the pond emulating tributary rivers. The setups were to enable the fishes to migrate out of the pond and spawn at the upper area (pool) of the canal. At the upstream of the canal, gravel beds were prepared on which the L. brevicephalus could spawn. Running (ready for spawning (stage 5)) male and female L. brevicephalus were placed in the pond. After a day long-acclimatization period lake water was pumped into the canal at a discharge rate of 250–1000 liters/min. Stimulated by the flow, 86 male and 24 female L. brevicephalus moved out of the pond migrated to the upper part of the canal made 16 spawning on the gravel beds, and returned to the pond. The fertilized oocytes (zygotes) were collected and it was possible to hatch them in aquariums in the laboratory.