Management of declining Japanese sardine, chub mackerel and walleye pollock fisheries in Japan

The density dependence of growth and body condition have important impacts on fish population dynamics and fisheries management. Although population density is known to affect the temperature of the habitat selected, how this affects the density dependence of growth and body condition remains unclear. Here, we investigated annual changes in body condition, habitat temperature, and cohort-specific growth of chub mackerel (Scomber japonicus) in the western North Pacific and examined quarterly changes in the density dependence of body condition. We hypothesized that chub mackerel body condition is affected both directly (e.g., through competition for food) and indirectly (through changes in habitat temperature) by the abundance of both conspecifics (i.e., chub mackerel) and heterospecifics (the Japanese sardine Sardinops melanostictus). Indeed, chub mackerel body condition, habitat temperature, and growth all decreased with increasing conspecific and heterospecific abundance. Mean annual growth rates in chub mackerel were positively corelated with body condition. The best model showed that conspecific and/or heterospecific abundance had strong negative effects on chub mackerel body condition in all seasons, and influenced habitat temperature in some seasons. By contrast, temperature effects on body condition were weak. Therefore, direct effects likely have more impact than indirect effects on density-dependent body condition and growth.

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Current state of the normative basis for processing of japanese sardine Sardinops melanosticta and chub mackerel Scomber japonicus as prospective commercial species in the Far East

Izvestiya TINRO ◽

10.26428/1606-9919-2015-183-284-289 ◽

2015 ◽

Vol 183 (4) ◽

pp. 284-289

Author(s):

Elena S. Chupikova ◽

Svetlana A. Selivanchik ◽

Eugene V. Yakush

Keyword(s):

Raw Materials ◽

Far East ◽

Chub Mackerel ◽

Japanese Sardine ◽

Commercial Species ◽

Standards And Regulations ◽

Technical Specifications ◽

Frozen Fish ◽

Industrial Standards ◽

Fish Industry

Effective utilization of marine biological resources is one of the major directions of the fish industry development in Russia that is realized by involvement into the fishery of unused and underused species. Japanese sardine and chub mackerel are still unused by Russian fishery but they are considered as prospective ones. On account of these prospects, the fund of standards currently in force in fish industry is analyzed in order to check possibility of their use for processing of these species. It includes mainly inter-governmental and industrial standards and regulations for manufacture of food and technical products. The age of these standards is 2-27 years, on average 14 years for the sardine and 13 years for the mackerel. The technical regulations and standards for frozen products of japanese sardine and chub mackerel are reviewed briefly. The standards GOST 814-96 «Chilled fish TU» and GOST 32366-2013 «Frozen fish TU» are recommended for the chilled and frozen products with a short shelf life, though they are not allowed for the raw materials destined for further processing at coastal fish enterprises. Recently new requirements for food safety are developing, so the current standards have to be reviewed and redeveloped, in particular the storage time of chilled and frozen products should be longer in 2-3 times. Variety of the products has to be extended, including canned and preserved ones, in particular new technical specifications for the specialized, medical-prophylactic products and dietary supplements should be developed or updated to the modern requirements. Role of standardization in improving quality and competitiveness of fish products and efficiency of the raw materials utilization is discussed.

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

Izvestiya TINRO ◽

10.26428/1606-9919-2021-201-3-23 ◽

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.

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