Biology and Population Status of Coastal Masu Salmon in Primorye, Russia

Masu salmon in Primorye, Russia are represented by two ecological forms. One form returns early to coastal rivers as large individuals in north Primorye and Khabarovsk Krai. They return during mid-May to late June and spawn in July and August. Most individuals in the spawning population are anadromous, but precocial males do contribute (ca. 5% of the spawning population).  Anadromous individuals average 6.5 kg. The other form occurs in the southern range, and they enter the rivers later.  These individuals are smaller (2-3 kg). The spawning consists of anadromous males and females and precocial resident males.  A large proportion of the male spawning population (46%) is composed of resident precocial males and males with limited estuarine residency. These individuals are smaller (< 1 kg).  Masu salmon dominate the fish community in rivers flowing into the Sea of Japan (average juvenile density: 0.11 ind / m2). Threats to the species include excessive fishing and degradation of habitat from logging practices.  According to our expert evaluation, 63.4% of all populations are threatened by illegal fishing, 27% are threatened by forest road construction and 5.6% are impacted directly by forestry practices.  Many populations are now maintained by hatcheries.