scholarly journals Species structure and year-to-year dynamics of nekton biomass in the upper epipelagic layer of the Pacific waters at Kuril Islands in summer periods of the 2000s

2014 ◽  
Vol 176 (1) ◽  
pp. 16-36
Author(s):  
Alexey A. Khoruzhiy ◽  
Svetlana V. Naydenko
Keyword(s):  
Kuril Islands ◽  
Species Structure ◽  
Pacific Waters ◽  
The Pacific ◽  
Upper Epipelagic Layer ◽  
Epipelagic Layer

scholarly journals Food supply for nekton in the epipelagic layer of Pacific waters at Kuril Islands in the summer seasons of 2000s

2014 ◽  
Vol 176 (1) ◽  
pp. 240-260
Author(s):  
Svetlana V. Naydenko ◽  
Alexey A. Khoruzhiy
Keyword(s):  
Diet Composition ◽  
Kuril Islands ◽  
Feeding Intensity ◽  
Deep Waters ◽  
Pacific Waters ◽  
The Pacific ◽  
Food Needs ◽  
Total Stock ◽  
Deep Water Part ◽  
Epipelagic Layer

Data of 8 surveys conducted by Pacific Fish. Res. Center (TINRO) in the Pacific waters at Kuril Islands in 2004-2012 are summarized to consider forage base and food relationships of nekton and plankton and to estimate consumption of forage resourced by nekton. The total stock of zooplankton and micronekton in the epipelagic layer changed from 62 to 158 million tons over the shelf and slope of the surveyed area and from 41 to 75 million tons in its deep-water part. Mezopelagic fishes, squids, pacific salmons, and subtropical fishes were the main consumers of these forage resources in summer. The portion of zooplankton stock consumed annually by nekton was relatively low: 4.2-9.3 % for shelf and slope areas (data for 2004, 2007, and 2011) and 4.5-15.6 % for the deep-waters (data for 2004, 2007, 2009, and 2011), without significant year-to-year changes in the diet composition and feeding intensity of nekton. There is concluded that zooplankton and micronekton of the studied area serve successively the food needs of its consumers and carrying capacity of the epipelagic layer in the Pacific waters at Kuril Islands is quite substantial.

scholarly journals Feeding of smoothtongue Leuroglossus schmidti in the Bering, Okhotsk Seas and adjacent waters of the Pacific Ocean

2016 ◽  
Vol 184 (1) ◽  
pp. 150-157
Author(s):  
Alexander Ya. Efimkin
Keyword(s):  
Bering Sea ◽  
Mesopelagic Fish ◽  
The North ◽  
Important Prey ◽  
The Pacific ◽  
Upper Epipelagic Layer ◽  
The Pacific Ocean ◽  
The North Pacific ◽  
Epipelagic Layer ◽  
The Bering Sea

Smoothtongue Leuroglossus schmidti is a small mesopelagic fish species common for subarctic waters. It rises to the upper epipelagic layer at night for feeding and preys mainly on euphausiids, copepods and amphipods. Its mean index of stomach fullness reaches 68 ‱ in the epipelagic layer, but it almost doesn’t feed deeper than 200 m, judging by a little food in the stomach. In the Bering Sea, euphausiids dominate in its diet and the portion of copepods is small. In the ​​Okhotsk Sea, each of these two groups provides a half of the diet. In the North Pacific, the portion of copepods is 63 % on average, euphausiids are the second important prey, and amphipods occur in the diet occasionally. Daily ration of smoothtongue is about 1.4 %.

scholarly journals «Wrong fish» or wrong hypotheses: what happens to nekton of the Pacific waters at Kuril Islands?

2021 ◽  
Vol 201 (1) ◽  
pp. 3-23
Author(s):  
V. P. Shuntov ◽  
O. A. Ivanov
Keyword(s):  
Structural Changes ◽  
Species Abundance ◽  
Kuril Islands ◽  
Chub Mackerel ◽  
Japanese Sardine ◽  
Cololabis Saira ◽  
Pacific Waters ◽  
The Pacific ◽  
Nekton Communities ◽  
The Kuroshio

A phenomenon of undulating fluctuations of nekton abundance in the Kuroshio system is discussed on example of japanese sardine Sardinops melanostictus, as the most abundant and the most fluctuating species. The so-called «sardine epochs» are distinguished according to this species abundance. The last such epoch ended in the early 1990s. Since 2014, structural changes occurred again in the nekton communities of the Pacific waters off Kuril Islands, caused by expansion of southern fish and squid species, primarily japanese sardine and chub mackerel Scomber japonicus, and decreasing in abundance of japanese anchovy Engraulis japonicus and saury Cololabis saira. The scope of these changes allowed Russian fishermen to resume the fishery on japanese sardine and chub mackerel in the Russian exclusive economic zone since 2016. Annual catch of Japanese sardine increased steadily from 6,700 t in 2016 to 315,500 t in 2020. Over these 5 years, Russian fishermen landed 531,700 t of sardine and 167,900 t of chub mackerel. However, many Russian fishery forecasters believe that these reconstructions is only a «rehearsal» of the upcoming «sardine epoch», being based on formal climatic indices, without delving into the mechanisms of abundance fluctuations. The authors note that new «sardine epochs» cannot be predicted as completely similar to the previous ones. Several hypotheses on causes of the beginning and end of japanese sardine blooms are considered critically, and the conclusion is made that mechanisms which determine its year-classes strength are still unclear, as well as the reasons of undulating fluctuations of this species and some other nekton species abundance, because of high complexity of this problem.

scholarly journals TO THE METHODOLOGY FOR SEPARATION OF MIGRATING POPULATION COMPLEXES OF THE OKHOTSK SEA PINK SALMON IN THE PACIFIC WATERS AT KURIL ISLANDS USING THE GONAD-SOMATIC INDEX

2020 ◽  
Vol 200 ◽  
pp. 24-37
Author(s):  
E. A. Shevlyakov ◽  
M. G. Feldman ◽  
V. A. Shevlyakov ◽  
A. N. Kanzeparova
Keyword(s):  
Pink Salmon ◽  
Kuril Islands ◽  
New Method ◽  
Trawl Survey ◽  
Okhotsk Sea ◽  
Gonad Somatic Index ◽  
Pacific Waters ◽  
The Pacific ◽  
Anadromous Migration ◽  
Somatic Index

New method is proposed for operational differentiation of pink salmon runs with different time of spawning and different state of gonads measured quantitatively with a gonad-somatic index. Results of this new method and traditional methods of differentiating are compared. The conception of spatial niches in the Pacific waters adjacent to Kuril Islands for certain temporal groupings of the Okhotsk Sea pink salmon is critically revised on the base of these new results. The runs cannot be separated using any fixed value of the gonad-somatic index. The zones of different groupings could be spatially overlapped. The method is tested on the data of trawl survey conducted aboard RV Professor Kaganovsky in May-July 2018, during anadromous migration of pink salmon, and shows a high compliance with the regional groupings ratio determined on the data of pink salmon catch in the Okhotsk Sea and their escapement to rivers. Tendency of the late-maturing forms of pink salmon to migrate through the southern Kuril waters is confirmed, whereas the portion of early-maturing pink has increased toward the Ocean.

Biology and Management of Dogfish Sharks

2009 ◽  
Keyword(s):  
Kuril Islands ◽  
Spiny Dogfish ◽  
Depth Range ◽  
Southeastern Kamchatka ◽  
Pacific Waters ◽  
The Pacific ◽  
Body Weights ◽  
Northern Kuril Islands ◽  
Catch Rates ◽  
The Northern Kuril Islands

Abstract.—Spiny dogfish <em>Squalus acanthias </em>are occasionally caught by bottom trawls in the Pacific waters off the northern Kuril Islands and southeastern Kamchatka. Only 23 specimens were captured during 8 years of commercial and research cruise observations from 1993 to 2000. This species occurred most frequently off the southeastern coast of Kamchatka within a depth range of 200–300 m and a bottom temperature range of 2°–3°C. In the study area, this shark was represented by specimens with total lengths of 54–85 cm (69.2 cm average) and body weights of 1–3 kg (1.8 kg average). Dogfish were captured in the Pacific waters off the northern Kuril Islands and southeastern Kamchatka from July to December. Maximum catch rates occurred in November and were probably related to southward migrations.

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