Interannual changes of biological properties of walleye pollock Theragra chalcogramma in the central Bering Sea

Yanagimoto, Takashi; Nishimura, Akira; Mito, K.; Takao, Yoshimi; Williamson, Neal J.

doi:10.1016/s0079-6611(02)00078-2

Cited by 7 publications

(8 citation statements)

References 18 publications

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“…), herring ( Clupea pallasi ), and Atka mackerel, but also include squid and octopus (class Cephalopoda). Large aggregations of pollock are found throughout the eastern Bering Sea and in the Unimak Pass and Unalaska areas during summer (Yanagimoto et al. , 2002; Logerwell et al.…”

Section: Discussionmentioning

confidence: 99%

Immature Steller sea lion (Eumetopias jubatus) dive activity in relation to habitat features of the eastern Aleutian Islands

Fadely

Robson

Sterling

et al. 2005

Fisheries Oceanography

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Current flow and bathymetry in the Aleutian Islands define unique habitats that influence prey distribution and foraging behaviour of top-level predators. We explored whether oceanographic features and bathymetry influenced the diving activity of 30 immature sea lions (ages 5-21 months) equipped with satellitelinked depth recorders in the eastern Aleutian Islands (EAI) during 2000-02. Sea surface temperature (SST) and chlorophyll a concentrations were obtained from remote sensing satellite imagery and associated with locations where sea lion diving was recorded. Most locations associated with diving to >4 m were within 10 nautical miles (nm) of shore and associated with onshelf waters <100 m deep. Use of offshore and deeper waters in the Bering Sea increased during May, as did trip durations. General movements at that time were generally northwesterly from the North Pacific Ocean to the Bering Sea. Diving activity varied coincidently with increases in SST and chlorophyll a concentrations, but also with sea lion age. Associations with habitat features did not consistently explain variability in dive count, time at depth, dive focus or focal depth. Nearshore diving tended to be influenced by distance from shore or seafloor depth, whereas increased SST coincided with activity of sea lions diving >30 nm offshore. Immature sea lions developing into independent foragers in the relatively shallow pass areas of the EAI do so at a time of rapid changes in oceanography and prey availability.

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Section: Discussionmentioning

confidence: 99%

Immature Steller sea lion (Eumetopias jubatus) dive activity in relation to habitat features of the eastern Aleutian Islands

Fadely

Robson

Sterling

et al. 2005

Fisheries Oceanography

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“…The biomass of walleye pollock in the Bogoslof region declined steeply in the 1990s from 1 289 006 t in 1991 to 301 402 t in 2000, and has been relatively stable at about 250 000 t in the 2000s . Simultaneously, the distribution of walleye pollock was diminished in the southeastern part of the Aleutian Basin (Yanagimoto et al 2002). In the present study, the weight of walleye pollock caught by research trawls was much lower than that of chum salmon in the basin area, and the catchability could be different for these 2 species (Azumaya et al 2003).…”

Section: Biomass and Roles Of Chum Salmon In The Bering Sea Pelagic Ementioning

confidence: 43%

“…Walleye pollock was the dominant planktivore in the Bering Sea basin during summer in the 1980s (Brodeur et al 1999, Shuntov et al 1999. The huge biomass of walleye pollock in the basin area was supported by reproduction mainly in the Bogoslof region in the southeastern part of the Bering Sea basin (Yanagimoto et al 2002). The biomass of walleye pollock in the Bogoslof region declined steeply in the 1990s from 1 289 006 t in 1991 to 301 402 t in 2000, and has been relatively stable at about 250 000 t in the 2000s .…”

mentioning

confidence: 96%

Biomass and mortality of chum salmon in the pelagic Bering Sea

Fukuwaka¹,

Sato²,

Yamamura³

et al. 2010

Mar. Ecol. Prog. Ser.

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To provide a key piece of information for understanding the functioning of the Bering Sea pelagic ecosystem, we estimated the biomass of immature chum salmon in the Bering Sea basin in autumn using a return-at-age analysis incorporated with the results of genetic stock identification studies. The estimated biomass was 742 000 t in 2002 and 617 000 t in 2003, which is possibly an underestimate because of the uncertainty of trawl selectivity parameters used in the estimation. Although chum salmon has been the dominant nekton species in the pelagic ecosystem of the Bering Sea basin in recent years, biomass estimates for the species were smaller than one-tenth of the maximum biomass of walleye pollock in the 1980s. Previous studies have highlighted the importance of the huge biomass of mesopelagic planktivores, such as myctophid fishes and gonatid squid, to the ecosystem function of the pelagic Bering Sea. Planktivorous Pacific salmon including chum and pink salmon may also play a significant role as competitors and predators of small planktivores, thus affecting the dynamics of ecosystem function and nekton community structure in the pelagic Bering Sea.KEY WORDS: Pelagic ecosystem · Planktivores · Biomass estimate · Salmon · Catch-at-age analysis · Genetic stock identification · Markov chain Monte Carlo Resale or republication not permitted without written consent of the publisherMar Ecol Prog Ser 403: [219][220][221][222][223][224][225][226][227][228][229][230] 2010 9.3 million (17 000 t) in 1972 (Fukuwaka & Morita 2008). The high-seas salmon gillnet fisheries were closed when the Convention for the Conservation of Anadromous Stocks in the North Pacific Ocean (NPAFC Convention) was enforced in 1993. However, the density index, i.e. number of chum salmon caught by research gillnets, increased in the 1980s and in the early 2000s reached levels 3-to 8-fold of those in 1972 (Fukuwaka et al. 2007). A biomass estimation of chum salmon in the Bering Sea would provide key information to aid in understanding the functioning of the Bering Sea pelagic ecosystem.Chum salmon originating from rivers in Pacific Rim nations migrate to the North Pacific and adjacent seas and finally return to their natal rivers to spawn after 2 to 5 yr of ocean life (Groot & Margolis 1991). From summer to autumn, chum salmon originating from many regions enter and mix in the Bering Sea (Seeb et al. 2004). For the international management of highseas salmon fisheries, stock identification techniques have been well developed using tagging experiments, scale pattern analysis, otolith marking, and genetic techniques (e.g. Tanaka et al. 1969, Myers et al. 1996, Urawa et al. 2000, Seeb et al. 2004. After the closure of high-seas gillnet fisheries, the oceanic abundance of immature chum salmon could be estimated from the number of returns-at-age with an assumed or estimated value of natural mortality. However, return-atage data are not always available for all chum stocks around the North Pacific. The basic idea of the present study was th...

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“…In the Bering basin population, remarkable changes in the length-fecundity relationship occurred with dramatic population declines between 1984 and 1999, but fecundity of spawners <450 mm did not change (Yanagimoto et al, 2002). In the present study, therefore, I assumed little change in length-fecundity relationships around L m over time.…”

Section: Fecunditymentioning

confidence: 76%

“…Length-fecundity relationships were taken from Hinckley (1987) in the Bering shelf population, Yanagimoto et al (2002) in the Bering basin population, Miller et al (1986) cited in Kendall and Nakatani (1992) in the Gulf of Alaska population, Hamatsu et al (2004) in the Japan Pacific population, and Zver'kova (1978) in the northern Japan Sea population. In the Bering basin population, remarkable changes in the length-fecundity relationship occurred with dramatic population declines between 1984 and 1999, but fecundity of spawners <450 mm did not change (Yanagimoto et al, 2002).…”

Section: Fecunditymentioning

confidence: 99%

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

Kooka

2012

Fisheries Research

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Interannual changes of biological properties of walleye pollock Theragra chalcogramma in the central Bering Sea

Cited by 7 publications

References 18 publications

Immature Steller sea lion (Eumetopias jubatus) dive activity in relation to habitat features of the eastern Aleutian Islands

Immature Steller sea lion (Eumetopias jubatus) dive activity in relation to habitat features of the eastern Aleutian Islands

Biomass and mortality of chum salmon in the pelagic Bering Sea

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

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