Problems in the "brown bear – salmon – human" relationship on the Pacific coast of Russia

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Problems in the “brown bear - salmon - human” relationship on the Pacific coast of Russia

Seryodkin I.V.

ORCID: 0000-0003-4054-9236, PhD in Biology, Associate Professor,

Pacific Geographical Institute of Far Eastern Branch, Russian Academy of Sciences, Vladivostok, Russia

Аннотация

Показана роль бурого медведя, лососей и их взаимоотношений в функционировании экосистем тихоокеанского побережья России. Лососи, заходящие в реки на нерест, играют важную роль в питании медведей, влияя на состояние их популяций. Сезонное распределение медведей и их перемещения во многом определяются распределением и обилием лососей. Лососи в свою очередь выполняют функцию переноса питательных веществ с моря на сушу. Между медведями и лососями на Дальнем Востоке имеются тесные межпопуляционные связи. Человек активно влияет на прибрежные экосистемы, добывая лососей и медведей, трансформируя их местообитания. Обозначены основные проблемы взаимоотношений в системе «бурый медведь - лосось - человек» и предложены возможные пути их решения.

Ключевые слова: Ursus arctos, Oncorhynchus, экосистема.

Abstract

The role of brown bear, salmon and their relationship in the ecosystems of the Pacific coast of Russia described in the paper. Salmon entering the rivers for spawning play an important role in the feeding of bears, affecting the population status. Seasonal distribution of bears and their movement is largely determined by the distribution and abundance of salmon. Salmon, in turn, performs the function of transferring nutrients from the sea to land. There are close interpopulation connections between bears and salmon in the Far East. People actively using coastal ecosystems, inhabited by salmon and bears, and transforming their habitats. Outlined the main problems of the relationship in the system “brown bear - salmon - human” with presentation of possible solutions.

Keywords: Ursusarctos, Oncorhynchus, ecosystem.

Pacific coast of Russia is a part of the brown bear (Ursusarctos) area, where it inhabits Magadan Region, Chukotka Autonomous District, Kamchatka Krai, Khabarovsk Krai, Sakhalin Region and PrimoryeKrai. The population density of bears in the region is one of the highest in Russia, ranging from 0.04 individuals / 10 km² in Chukotka Autonomous District to 0.4 individuals / 10 km² in Kamchatka Region [1]. In some places, particularly, in the basin of Kuril Lake (Kamchatka Peninsula), bears density reached 32 individuals / 10 km² [2]. The population density of bears along the coast usually is higher than that further in the mainland. Presence of food attract bears and they can create temporary concentrations along the coast. bear ecosystem salmon human

Pacific salmon spawning in the rivers of the Pacific coast is among the main food sources of brown bears in the Far East of Russia. This type of food is high-calorie and feeding on it bears accumulate sufficient amount of fat required for surviving in difficult periods of winter and early spring [3], [4]. Presence of salmon along the Pacific coast is critical for reproductive success and overall well-being of brown bear populations. The most important species of Pacific salmon for brown bear are pink salmon (Oncorhynchus gorbuscha), chum salmon (O. keta), masu salmon (O. masu), sockeye (O. nerka) and coho salmon (O. kisutch). Salmon is the most important food for bears in the summer-autumn period [2], [5], [6].

Brown bears play an important role in coastal ecosystems due to intensive feeding on salmon returning to rivers and lakes for reproduction. The bodies of salmon represent a transfer of nutrients from the ocean to the forest ecosystem by bears, as the main utilizers of dead fish. This role of bear in coastal ecosystems largely determines their function. Brown bears and salmon are the keystone species of the Pacific coast ecosystems and spawning rivers basins. The balance in the interaction of these species determines the well-being, singularity and long-term existence of ecosystems.

People actively using coastal ecosystems, including their natural components - bears and salmon. This influence is expressed in the procurement and displacement of bears, reduction of their food supply, habitat destruction, harvesting of salmon, reduction of the spawning areas and pollution of habitat.

The main threats to the stable existence of brown bear populations in the Far East are poaching, habitat loss, competition for food resources with human, and insufficient management of population. Brown bears are legally hunted species on the whole territory of the Far East. However, poaching of bears is widespread in the region. They are killed for sale of derivatives (distal parts of paws, bile), personal consumption (meat, fat), to eliminate competitors on river when fishing salmon, as well as in conflict situations with people [7].

Nowadays, one of the main threats to the existence of brown bears in the Far East of Russia is displacement of bears from their natural habitat by people, which is leading to the lack of food resources for the animal. In the south of the region (Primorye Krai and southern part of Khabarovsk Krai) another problem is massive collection of Korean pine nuts (Pinus koraiensis) by the local population, which is one of the main fattening food source for brown bears. Commercial fishing and poaching of salmon along the Pacific coast creates difficulties in bears feeding, accumulation of fat reserves, limits their distribution and, ultimately, affects the density and health of the population.

Harvesting on the salmon is growing for the last two decades. The annual catch of Pacific salmon in the Sakhalin region was growing constantly reaching the absolute historical maximum in 2009 - 294,000 tons. The high level of catches of salmon is achieved not only by the constantly increasing number of fishnets in the sea, but also by fish counting barriers established in 2009. Commercial fishing of pink salmon and chum salmon using fish counting barriers performed directly in the spawning rivers by complete blocking of the channel. According to the regulations, the number of salmon allowed into the rivers for natural reproduction is increases by 20% from the maximum spawning capacity to compensate for the inevitable death during migration of fish from fish counting barriers to spawning grounds. However, these calculations are not sufficiently substantiated, and control over the execution of the regulations is not carried out adequately. In the context of the growing demand of people in salmon products the science-based approach is needed to create balance between acceptable withdrawal of fish without disturbing the integrity and functioning of coastal and aquatic ecosystems.

Research programs for the study of ecology of brown bears with various methods, including visual observation, study of traces of vital activities, camera traps, radio- and GPS-collaring [8], [9], [10] are implemented on Sakhalin Region, Kamchatka Krai and Primorye Krai. An important goal of these studies is exposing the complex of relations in the “human - salmon - brown bear” system and the prevention of humans-predators conflicts. These programs are aimed to study the most important issues of brown bear biology required for their conservation and conflict-free coexistence with humans. The studies show the exceptional role of salmon in all aspects of the brown bear ecology: feeding, daily and seasonal activity, intensity and the distance of seasonal movement, the use of habitat, preference of habitat in different seasons, intraspecific and interspecific relations etc. For instance, with the use of satellite telemetry it is shown that home ranges of bears in the summer period are confined to the sea coast and spawning rivers where animals feed on salmon [9] (Fig. 1).

Imbalance in the “bear - salmon” system may affect not only the well-being of populations of these animals, but also the sustainability of ecosystems, there they are the essential elements. Island ecosystems are most vulnerable. For example, the influence of salmon on Sakhalin extends to the whole island and all its ecosystems. Disturbance of the food chain “salmon - bear” can cause changes in the scheme of the drift of substances that has formed historically thru the interaction of species, causing violation of relationships and imbalance in ecosystems.

Fig. 1 - Home ranges and habitats of three GPS-collared bears confined to the coast and a spawning river in the eastern Sakhalin in the summer of 2011 [9]

Well-being of brown highly depends on Pacific salmon and it is an important element of strategy for the conservation of this species in the Russian Far East, based on protection of the populations of salmon entering fresh water for spawning, and salmon resources by people considering the demands of bears and other animals. Poaching of salmon, killing of bears by poachers as competitors on rivers, overfishing of salmon - are the main threats to the population of brown bears in the region. Increasing protection of spawning rivers from poachers and revising the existing standards of permissible withdrawal of salmon are the necessary steps for conservation of the predator.

Список литературы / References

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Список литературы на английском языке / References inEnglish

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