Definition of the major limiting factors
In the majority of river basins of the South of the Far East deterioration of the environment hasn't reached yet that level when it can limit the number of salmon. To Hokkaido these factors are represented decisive for total disappearance of Sakhalin taimen of number of the rivers.
For the Russian part of an area the main reason, without exaggeration, a catastrophic situation with survival of populations of a taimen through passage is excessively high mortality under impact of both poaching, and trade fishing and amateur catch (Zolotukhin et al., 2000; Safronov, 2004; Zolotukhin, Semenchenko, 2008; Nikitin, 2012). Recently there is a lot of negative information on specialized poaching of the Sakhalin taimen, including representatives of indigenous peoples, on the rivers and gulfs of the Northeast.
Trade and in general any catch of a taimen on Sakhalin is forbidden, but he comes across as becatch when catching other fishes. Both fishermen-field men, and fans, as a rule, don't release caught taymen.
During actions for regulation of the admission on spawning of producers of the Pacific salmon (pink and chum salmon) on the fish-counting obstacles and on the salmon hatcheries there is a restriction of natural local migrations on "the sea-the river" type. In cases of excessive restriction of the admission for spawning of producers of the Pacific salmon there is a decrease in the main food supply of juveniles of the Sakhalin taimen. Trade of fodder objects of a taimen also influences conditions of his survival.
When catching salmon various amateur hook tackles as bycatch also the Sakhalin taimen comes across. In most cases fishers don't release him (including where it is considered a protected species). Specialized fishing of trophy fish is often carried out. "Caught-release" the principle applied sometimes at the same time not fully keeps the released individuals as it is applied not properly and inadequate tools of fishing are used. Trophy copies sometimes are implemented on food and on production of souvenirs.
Total analysis of indicators of degradation of species
The Sakhalin taimen Parahucho perryi (Brevoort) - an excellent species indicator; existence of his healthy herd in this river basin - reliable sign of favorable natural conditions for salmon and also the moderate mode of fishery (including impact of sports fishing).
The initial small number and low ability to reproduction promotes the fastest disappearance of local populations in the conditions of the increasing anthropogenic press. Producers of taimen rather late, spawning of this species – not annual ripen, many mature individuals don't participate in reproduction. All this indicates adaptations of species to rather low natural mortality and very small natural potential of his reproduction.
Judging by fast and total disappearance of herds of taimen in many small rivers, this species differs in rigid homing, and exchange of individuals (wandering) even between adjacent pools is small. It indicates the small number of the majority of local populations of this species and of their special vulnerability.
Special biological characteristics of taimen are also deeply involved in sharp reduction of this species: it is extremely later in comparison with others salmon maturing, it is need of long migration upstream to the place of spawning, it is a possibility of repeated return on spawning, this main habitat (except for the reproduction period) in the regions of the lowermost current which have undergone considerable destructions of the nature (flattening, drainage, etc.). These properties in significantly the changed environment, or are more right in artificially changed environment, create very adverse conditions for preservation of population of taimen (Fukushima et al., 2008).
Very small stream of genes between populations and the essential distinctions which are observed between them on morphology and biology indicate preservations of the various populations of species living throughout his area the need.
The Sakhalin taimen belongs to category of most obvious "candidates" for special protection (Viability of populations, 1989). Bases for this purpose a little:
- The predator regulating the number of populations of other species and which absence finally leads to falling of a specific variety.
- A species which representatives from the human point of view have spiritual, esthetic, recreational or economic value.
- The rare species which has appeared under the threat of disappearance because of the person.
The Sakhalin taimen belongs to category of species especially subject to extinction and needing careful protection and control (Primak, 2002):
- Species with rather narrow area.
- Species with the small size of the isolated populations.
- Species showing steady signs of reduction of the sizes of populations.
- Species with the low density of local populations.
- Species for which throughout life cycle big territories are necessary.
- Species of the large size.
- Species incapable of independent resettlement.
- Species – the seasonal migrant.
- Species with a low intra population genetic variety.
- Species with rather highly specialized requirements to an ecological niche.
- Species living in the stable environment (K-strategist).
- Species forming temporary aggregations (wintering).
- Species which the person hunts.
For Far Easterners the Sakhalin taimen is a charismatic, "flag" species, the same live symbol of salmon ecosystems as the Amur tiger – a symbol of taiga ecosystems. In case of possible loss the unique taxon – an ancient monotypical genus will disappear. His resource, scientific and indicator importance is extremely high. It is a perspective object for development of ecological tourism. Measures of his physical and territorial protection and also ecological and educational work are obviously insufficient.
Conservation of the Sakhalin taimen became focus of the international attention of nature protection and scientific community. The international seminars and symposiums devoted to this species and a genus of taymen have taken place in New Zealand, Japan and Poland (Makeev, 2012; Rand, 2012; Semenchenko, 2012). The Sakhalin taimen is included in the list of 100 main endangered species of world fauna made by IUCN and the London zoological society.
We urge the Government of the Russian Federation to assume global responsibility for conservation of a unique species.
In 2017 together with members of Sakhalin Taimen Conservation Network and activists collective expert assessment of threats concerning ST and prioritization of nature protection actions is carried out. As a result the draft of "The action plan for conservation of the Sakhalin taimen in the Northeast of Sakhalin" is made and widespread.