Oncorhynchus penshinensis is found in the rivers of Kamchatka, Russia. The population size of this species is unknown, although in the northern rivers of western Kamchatka the species is abundant. In the south there has been a sharp decline in numbers despite a ban on fishing. Threats to this species include over exploitation and illegal fishing, despite bans, as well as agricultural pollution leading to habitat degradation. This is in addition to limiting factors of relatively low reproduction capacity of the species, lack of suitable spawning grounds and feed resources. This species is, however, widespread and included within the boundaries of multiple protected areas. Therefore, this species is assessed as Least Concern. Conservation measures are recommended and monitoring of its population.

Oncorhynchus penshinensis is found in the rivers of Kamchatka, Russia: along the south-eastern and south-western coasts from Uka and Nachiki (eastern coast) down to Avachinskaya Bay rivers and northwards to the Kinkil'. In western Kamchatka, this species occurs from Amanina River in the north to Bol'shaya River in the south. Historical records from eastern Kamchatka are only from Kalakhtyrka Lake near Petropavlovsk (Avachinskaya Bay) and north of Ozernaya River (Berg 1948, Krogius et al. 2010). Cheresnev (1996) records this species in the eastern Kamchatka, specifically in the rivers Uka and Nachika, Kamchatka River, rivers of Kronotski Bay (Zhupanova, Nalycheva, Ostrovnaya), and in western Kamchatka within in most drainages, and the northern distribution border is Kinkil' River. This species is absent from Rekinniki River and further north.

The population size of this species is not determined (Tokranov and Sheiko 2006). There is no official fishing, but because of the gastronomical value of this fish it is caught in large numbers by poachers and numbers are also limited by the limited areas suitable for spawning and forage resources in the rivers for young fish (Tokranov and Sheiko 2006). The largest subpopulations (at least a few thousand individuals per year) are known in the northern part of the range, in the area of the Cape Utkholok (Tokranov and Sheiko 2006). In the northern rivers of Western Kamchatka the species is abundant. Numbers are unknown in the central part of the range, while in the southern part (Bolshaya River Basin) they are steadily decreasing due to intensive illegal catches (Tokranov and Sheiko 2006). Here, agricultural production may also have a negative impact on breeding success. Limiting factors also include relatively low reproduction capacity of the species, lack of suitable spawning grounds and feed resources (Tokranov and Sheiko 2006).

An anadromous fish, this species lives in fresh water up to 1-4 years, and in the sea from 2-6 years (Reshetnikov 2002, Tokranov and Sheiko 2006). This species enters the small tundra rivers for spawning in autumn from September to November, the peak of the move in late October, with some fish going under the ice (Reshetnikov 2002, Tokranov and Sheiko 2006). This species winters in the lower and middle reaches of the rivers in pits and in early spring, migration to upstream spawning grounds continues (Reshetnikov 2002, Tokranov and Sheiko 2006). This species matures at the age of 4-5 years. Spawning in late May to mid June in a strong current, during the flood period at 1-5°C (Reshetnikov 2002, Tokranov and Sheiko 2006). Eggs are laid in redds made of pebbles and gravel, built in places of transition from pits to rolls, at a depth of 0.5-2.5 m (Reshetnikov 2002, Tokranov and Sheiko 2006). This species reproduces 1-5 times in its life; most fish after the first spawning die, the rest immediately roll into the sea (Reshetnikov 2002, Tokranov and Sheiko 2006). Fecundity of this species is 3.3-12.8 thousand eggs. The incubation period lasts 3-5 weeks. Young salmon in the river feeds on falling insects, benthos organisms and young fish, and in the sea they lead an exclusively predatory life style, eating fish and large invertebrates (Reshetnikov 2002, Tokranov and Sheiko 2006). Fully grown length reaches 100 cm, body weight is 11-12 kg, and life expectancy 10-11 years (Reshetnikov 2002, Tokranov and Sheiko 2006).

In South Kamchatka there has been a sharp decline in numbers despite a ban on fishing (Tokranov and Sheiko 2006). There is no official fishing, but because of the gastronomical value of this fish it is caught in large numbers by poachers (Tokranov and Sheiko 2006).

In the southern part of the range (Bolshaya River Basin), agricultural production may also have a negative impact on breeding success.

There is no official fishing, but because of the gastronomical value of this fish it is caught in large numbers by poachers (Tokranov and Sheiko 2006).

This species is included in the Red Book of the Russian Federation and the Red Book of the North of the Russian Far East in Category 1; Reducing in number, rare species (Tokranov and Sheiko 2006). It is consdiered Endangered in some river basins of Kamchatka (Bolshaya, Mitoga, Utok). According to the Fishery Regulations, all kinds of catch are prohibited. In addition to protection of migration routes and spawning grounds against poaching, it is necessary to prohibit fishing of all species of Pacific salmons in the estuaries of the rivers where the species enters, from the start of September. This species occurs in multiple protected areas, including Fgbu Kronotsky State Reserve, Russia. It is necessary to expand the borders of the Utkholok Zakaznik (a protected area) to include the left bank of the Utkholok River and the Snatolvaiam River basin, as well as to establish specialised protected areas in the central and southern parts of its range. There is a need for studies of population status on the eastern coast of the peninsula, monitoring of the entire species range and cryopreservation of genomes of local subpopulations (Tokranov and Sheiko 2006).

While focus on species-level status assessments are an important first step, the IUCN Species Survival Commission (SSC) Salmon Specialist Group (SSG) emphasizes the need to characterize status of Pacific Salmon at a more granular, population-level scale (identified as “subpopulations” in the IUCN Red List Guidelines) to provide meaningful guidance to stem the loss of biodiversity across the natural range of the species. There are many examples of declines in wild Pacific Salmon in both North America and Asia, particularly in the southern portion of their range given the degree of degradation and fragmentation of habitat there and the more immediate risk of climate change impacts. At the same time, there are large-scale ocean drivers that appear to be affecting species broadly across the North Pacific, regardless of their freshwater origin. Two excellent examples exist of assessment approaches and policies in the US (Waples 1991) and Canada (DFO 2005, COSEWIC 2018) that establish an effective framework for Pacific Salmon conservation. These efforts involve identifying population units based on a variety of criteria including examination of traits that are important in the evolutionary process and future adaptation. In these examples, assessments are conducted at a more granular, population-level, resulting in listings for individual population units, with identification of needed conservation actions specific to each unit. An example of assessing range-wide status of the species and at the individual subpopulation level in the IUCN Red List now exists for Oncorhynchus nerka (Rand 2011). While the amount of effort required to rigorously assess the species is substantial, we encourage efforts like this applied to the other species in the genus.