Изменения в составе донных ихтиоценов на шельфе Авачинского, Кроноцкого и Камчатского заливов под влиянием промыслового пресса

• Main Authors: Коростелев, С., Василец, П.
• Format: Text
• Language: unknown
• Published: Федеральное государственное унитарное предприятие «Тихоокеанский научно-исследовательский рыбохозяйственный центр» 2004
• Subjects: Bering Sea; Okhotsk; Pacific; Kamchatka; КАМЧАТК*
• Online Access: http://cyberleninka.ru/article/n/izmeneniya-v-sostave-donnyh-ihtiotsenov-na-shelfe-avachinskogo-kronotskogo-i-kamchatskogo-zalivov-pod-vliyaniem-promyslovogo-pressa; http://cyberleninka.ru/article_covers/8864997.png

Показано, что полидоминантные донные ихтиоцены в заливах тихоокеанского побережья Камчатки при среднем уровне промыслового пресса формируются в основном из представителей двух семейств рогатковых и камбаловых, в каждом из которых четко обозначается доминирующий вид широколобый шлемоносный бычок и двухлинейная камбала. Чрезмерный промысловый пресс приводит к замене доминирующих видов. В семействе рогатковых начинает преобладать пестрый получешуйник, а в семействе камбаловых палтусовидная камбала. Продемонстрировано, что под влиянием комплекса естественных и антропогенных факторов сообщество донных рыб может переходить из монодоминантного состояния в полидоминантное и, по-видимому, наоборот. Снижение биомассы трески наряду с уменьшением общей биомассы донных рыб, а соответственно и увеличение полидоминантности в большей степени связано с причинами естественного характера. The problem of large marine ecosystems (as the ecosystem of the Okhotsk or Bering Sea, for example) studies and analysis of fisheries impact for the ecosystems is a high species diversity of bottom ichthyofauna. The process of the fisheries influence on the composition of bottom fish community can be investigated more conveniently for smaller ecosystems, like the ecosystems the of Avachinsky, Kronotsky and Kamchatsky Bays located at the Pacific coast of Kamchatka. The bays have similar bottom ichthyofauna but different fisheries activity. The following data from daily reports of fishing vessels collected by the "Fishery" Information System in Kamchatka Center of Monitoring and Coordination were used for the fisheries activity monitoring: date and coordinates of a fishing operation, type of the gear, number of fishery operations per a day, duration of the fishing operations, summary catch per a day by the species. Bottom fish community composition in the bays was determined by trawl surveys in 1984, 1999 and 2002. Bottom fish were caught mostly with Danish seine. The Danish seine fishery increased in the period from 1997 to 2001 and stabilized in 2002. The maximal fishery press per a square unit occurred in Avachinsky Bay, it was twice lower in Kronotsky Bay, and was minimal in Kamchatsky Bay. The total abundance of bottom fish communities in the bays varied insufficiently being practically stable in time, but their structure changed considerably. In 1980-s, cod dominated among the bottom species (it was more than a half of the total biomass), flounders (basically the northern rock sole) were usual species, and sculpins contributed insufficient part of the bottom community (among sculpins, the purplegrey sculpin was the most numerous, about 50 %). In 1999 the biomass of cod became extremely low in all bays of the Pacific coast of Kamchatka, and about a half of the biomass of bottom fishes was flounders in Kamchatsky and Avachinsky Bays and sculpins in Kronotsky Bay. In all bays the northern rock sole still dominated among flounders, and purplegrey sculpin among sculpins. So, the bottom fish communities have transformed from mono-dominant to multi-dominant ones during the last decade of XX Century. Cod depression continues, and in 2002 the biomass of the cod was 14 %, 6 % and 3 % of the whole ichthyofauna in Kamchatsky, Avachinsky, and Kronotsky Bays, accordingly. Recently, flounders dominate in Kronotsky and Kamchatsky Bays, and sculpins in Avachinsky Bay; the northern rock sole dominate among flounders in Kronotsky and Kamchatsky Bays, but flathead sole in Avachinsky Bay; great sculpin dominate among sculpins in Kamchatsky Bay, purplegray sculpin in Kronotsky Bay, and yelloy Irish lord in Avachinsky Bay. Obviously, recent changes of the bottom fish communities' composition are caused by increasing of fishery activity until 2001. In nowadays, the fisheries activity in the bays of the Pacific coast of Kamchatka can be characterized as the following: low fishery press in Kamchatsky Bay, moderate press in Kronotsky Bay, and overpress in Avachinsky Bay. The observed decreasing of cod abundance and developing a multi-dominant state of bottom fish communities are supposedly caused by natural factors. The multi-dominant communities have been formed at the moderate level of fishery press, mostly from the representatives of sculpins and flounders, with one species predominance for each family (as purplegray sculpin and northern rock sole). Overpress of fishery (in Avachinsky Bay recently) causes change of the communities structure toward yelloy Irish lord dominance among sculpins and flathead sole among flounders. The bays of the Pacific coast of Kamchatka could be regarded as natural testing areas for developing a strategy and tactics of fishery management, especially for multi-species fishery.