Distribution and abundance of the arfak rainbowfish, Melanotaenia arfakensis Allen, 1990 in Prafi River system, Manokwari, West Papua: due to habitat degradation?

Abstract

Arfak rainbowfish, Melanotaenia arfakensis, is one of the freshwater endemic fish in Manokwari, West Papua. The presence of the Arfak rainbowfish is currently experiencing many disturbances related to anthropogenic activities. This research, therefore, was conducted to describe habitat condition, distribution and abundance of the Arfak rainbowfish in the Prafi River system spatially. This study was conducted for 12 months on 12 sites in Nimbai and Aimasi Streams, the Prafi River system. The results showed that this species was mainly distributed in the upper reaches of the Nimbai and the Aimasi streams based on the frequency of occurrence (>90.9%) and relative abundance (25.5%). The lower fish occurrence and abundance was found at site of the sewerage and downstream. The highest value of the habitat utilization overlap index between Arfak rainbowfish and alien fish species was found in lower reaches. Decreasing habitat quality in lower reaches of the river causes limited distribution and decline in abundance of this species. To conserve this endemic fish population, it is necessary to maintain habitat condition in the upstream area and restore the damaged habitat in lower reaches of the Prafi River system.