Spawning migration and habitat characteristics of Labeobarbus species in the Gumara River and its tributaries, Lake Tana subbasin, Ethiopia

Abstract

Information on the spawning migration and habitat use of migratory fish is critical to protect and restore threatened or endangered populations. Twenty-two individuals of three species, namely Labeobarbus platydorsus, L. megastoma, and L. truttiformis, were implanted with radio tags to study their spawning migration in the Gumara River and its tributaries between July and October of 2018 to 2021. Fourteen individuals were found at least twice throughout their migration, eleven moved upstream up to 41.0 and 44.4 river kilometers (rkm), and three were tracked when moving downstream. The upstream spawning movement of the tagged fish lasted 9 to 27 days, and their ground speeds ranged from 0.07 to 1.50 km h-1. The habitat use of untagged Labeobarbus specimens in the spawning sites was also assessed using fyke nets, cast net fishing, and data from fishermen’s catches. Labeobarbus truttiformis mainly exploited the Kizen tributary stream with gravel substrates and less turbid water for spawning. Several small-sized individuals of L. megastoma spawned in the Wonzuma and Dukalit tributaries. By contrast, larger-sized specimens of L. platydorsus and L. megastoma spawned in the main river channel at the riffles and the gravel/pebble size substrate. Destructive fishing using gillnet dragging, filtering, and damming/fencing has recently intensified at the spawning areas (~ 41.0 rkm to 45.0 rkm), which likely affects spawning populations. Therefore, we recommend that fishing in the main river channel and tributaries must be banned during the months of August, September, and October to safeguard and conserve the threatened Labeobarbus species.