Life-history traits of walleye pollock, Theragra chalcogramma, in the northeastern Japan Sea during early to mid 1990s

Kooka, Kouji

doi:10.1016/j.fishres.2011.09.001

Cited by 8 publications

(4 citation statements)

References 49 publications

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“…For the second, third, and forth sampling quarters, we assumed the smallest group was age-0. The means of the length frequency distributions of these groups approximately corresponded to the body lengths of Bering Sea walleye pollock at age (47,156,246, and 320 mm for ages 0, 1, 2, and 3, respectively) calculated from the life history parameters reported in Kooka (2012).…”

Section: Apportionment Of Pollock Predation Into Age Classesmentioning

confidence: 75%

“…Individual pollock prey were then assigned to one of four age classes (0, 1, 2, and 3+) by their body length, based on the probability calculated above. Body weights of individual prey were estimated from their body length and the length–weight relationship for the Bering Sea shelf stock of walleye pollock reported in Kooka (). Individual prey weights were summed by prey age class, predator, and sampling year.…”

Section: Methodsmentioning

confidence: 99%

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Multispecies biomass dynamics models reveal effects of ocean temperature on predation of juvenile pollock in the eastern Bering Sea

Uchiyama

Mueter

Kruse

2019

Fisheries Oceanography

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Walleye pollock (Gadus chalcogrammus) supports one of the largest commercial fisheries in the world. Juvenile pollock are important forage fish in the eastern Bering Sea (EBS) ecosystem, often representing the largest fraction in the diets of major Bering Sea piscivores. Large variability in the EBS pollock stock biomass in recent years has been attributed primarily to fluctuations in recruitment. It has been hypothesized that predation rates on forage fishes increase when the cold pool (a body of cold water < 2°C) is extensive and covers much of the middle continental shelf, which tends to concentrate larger predatory fishes in the outer shelf and slope regions. In contrast, young pollock appear to tolerate colder temperatures than older fish and can stay in the cold pool, thereby reducing predation. We used a multispecies modeling approach to examine the effects of the cold pool size on predation of juvenile pollock. We found that predation on age‐1 pollock by age‐3+ pollock decreased, and predation on age‐1 and age‐2 pollock by arrowtooth flounder increased with increasing bottom temperature, which was used as a proxy for the cold pool size. These results suggest that the cold pool creates spatial separation between juvenile pollock and arrowtooth flounder, but not between adult and juvenile pollock. The model developed in this study could be used to examine the effects of other covariates on interspecific interactions, help explain observed changes in fish communities, and understand implications of climate change on ecosystems and their productivity.

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Section: Apportionment Of Pollock Predation Into Age Classesmentioning

confidence: 75%

Section: Methodsmentioning

confidence: 99%

Multispecies biomass dynamics models reveal effects of ocean temperature on predation of juvenile pollock in the eastern Bering Sea

Uchiyama

Mueter

Kruse

2019

Fisheries Oceanography

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“…Several biotic and abiotic factors, such as water temperature, prey availability, and population density, cause inter‐ and intrapopulation variations in life history traits (Belk ; Hamatsu and Yabuki ; McDermid et al. ; Kooka ). Among them, seawater temperature is one of the most pervasive abiotic factors influencing aquatic organisms (Fry ; Brett et al.…”

Section: Discussionmentioning

confidence: 99%

Changes in the Biological Characteristics of Walleye Pollock Related to Demographic Changes in the East Sea During the Late 20th Century

et al. 2018

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Walleye pollock Gadus chalcogrammus (hereafter, pollock) was one of the predominant fish species in Korean waters during the 1970s and 1980s, but catches decreased rapidly beginning in the late 1980s and the fishery collapsed in the 2000s. The biological characteristics of fish species tend to depend on their biomass and environmental conditions. To investigate the changes in the biological characteristics of pollock (such as their size frequency, condition factor, and maturation) associated with biomass levels as well as the possible causes of the stock collapse as a result of environmental changes, we used data collected by the Korean National Institute of Fisheries Science (NIFS) during high (1976)(1977)(1978)(1979)(1980)(1981)(1982)(1983)(1984)(1985) and low (1991-2000) periods of pollock biomass. Density-dependent effects on the pollock population were evident in Korean waters: pollock were larger and heavier at length during the low-biomass period. The gonadosomatic index also indicated that the peak spawning season was broad (from October to February) during the high-biomass period and narrower (December and January) during the low-biomass period. The population abundance and recruitment success of Korean pollock appear to have been affected by the warming of the ocean surface from the early 1990s. Thus, we suggest that the biomass fluctuations associated with environmental changes during their early life stages were responsible for the observed changes in the biological properties of pollock.

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“…CPUE CPUE 10 3 , , Park et al (1978) , Park et al (1978) . , Kooka (2012) , Park et al (1978Park et al ( ) 1974Park et al ( -1978 , .…”

Section: 어획의 영향mentioning

confidence: 99%

A Life Stage-based Model for Assessing the Walleye Pollock Gadus chalcogrammus Population in the East Sea

Kim¹,

Sohn²,

Hyun³

2017

Korean Journal of Fisheries and Aquatic Sciences

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Since the late 1990s, walleye pollock Gadus chalcogrammus fisheries in Korean waters have been considered collapsed. Although many fisheries scientists suspect that the collapse might have been triggered by overexploitation of juvenile pollock or environmental changes, such conjectures have been neither tested nor investigated, partially because of limited data on the population. There has been no survey of the population, and the ages of fish in fishery catch have rarely been identified. Instead, fishery catch data from 1975-1997 included information about two life stages, 'juveniles and adults,' and data on catch-per-unit-effort (CPUE) during 1963-2007 and those on fish length and weight during 1965-2003 had been sporadically collected from commercial fisheries. To test hypotheses about the collapse of the pollock fisheries, we used a statistical linear model with juvenile CPUE as the response variable, and abiotic (e.g., water temperatures) and biotic factors [e.g., adult pollock, flatfishes (Pleuronectidae sp.), and sandfish (Arctoscopus japonicus) CPUEs] as the explanatory variables. The model results indicated that depletion of the pollock population was associated with both biotic (adult pollock and flatfishes abundance) and abiotic factors (mid-water temperatures in February and October). We further interpreted the results from ecological and biological perspectives, suggesting possible mechanisms.

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Life-history traits of walleye pollock, Theragra chalcogramma, in the northeastern Japan Sea during early to mid 1990s

Cited by 8 publications

References 49 publications

Multispecies biomass dynamics models reveal effects of ocean temperature on predation of juvenile pollock in the eastern Bering Sea

Multispecies biomass dynamics models reveal effects of ocean temperature on predation of juvenile pollock in the eastern Bering Sea

Changes in the Biological Characteristics of Walleye Pollock Related to Demographic Changes in the East Sea During the Late 20th Century

A Life Stage-based Model for Assessing the Walleye Pollock Gadus chalcogrammus Population in the East Sea

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