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NAKATANI, Toshikuni; MAEDA, Tatsuaki

doi:10.2331/suisan.50.937

Cited by 29 publications

(7 citation statements)

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“…In addition, we used the mean water temperature of the 200-m and 400-m depth stations as that of the 300 m depth stations outside of Funka Bay as pre-spawning ground at 50 days before hatching and egg duration days (T-b50d + Edd). The egg duration days (Edd) were estimated from the formula between the mean days required for 50% hatching and water temperature (θ; C) according to Nakatani and Maeda (1984).…”

Section: Discussionmentioning

confidence: 99%

Effect of egg size on the growth rate and survival of wild walleye pollock Gadus chalcogrammus larvae

Kajiwara

Nakaya

Suzuki

et al. 2022

Fisheries Oceanography

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To clarify the survival process of walleye pollock larvae of the Japan Pacific stock in relation to the individual egg size, we estimated the original relative egg diameter from the diameter of the hatch check formed on larval sagittal otoliths. Significant positive correlations were obtained between egg diameter and embryonic body length, yolk sac volume, and lapillar otolith diameter in 3-year groups (2013-2015 year classes) collected with a plankton net in Funka Bay. Embryos before hatching were without a check; however, checks were observed on all larval otoliths just after hatching. The check diameters showed significant positive regressions to age at collection (days after hatching) in 2014 and 2015 year classes, however not in the 2013 year class. Diameters of eggs collected with a ring net in Funka Bay gradually increased from 2013 to 2015 year classes. During the 2013-2015 spawning seasons, the proportion of adult females of the 2007 and 2009 year classes, which had relatively high abundances, gradually increased to higher proportions with age (43%, 57%, and <73%, respectively), indicating that the mechanism by which the eggs gradually became larger. The low water temperature experienced by the spawners ca. 2 months earlier, advancement in spawner age, and increase of repeat spawners (at least twice in their life time) would contribute to the increase in egg size and growth and survival rate of walleye pollock larvae.

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Section: Discussionmentioning

confidence: 99%

Effect of egg size on the growth rate and survival of wild walleye pollock Gadus chalcogrammus larvae

Kajiwara

Nakaya

Suzuki

et al. 2022

Fisheries Oceanography

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“…In the experiment, the eggs were placed on surface grids, taking their density into account. The spawning grids were determined by their suitable spawning temperature range (2 °C-5 °C) and the appropriate habitat depths (50-500 m) for walleye pollock [10,21,[50][51][52]. We considered the potential spawning ground located in the EKB between 36°N and 41°N (figure 1(b)).…”

Section: Particle Tracking Experimentsmentioning

confidence: 99%

“…In the early life stage of walleye pollock, eggs and larvae drift passively towards nursery grounds carried by ocean currents. During this transportation process, they can be susceptible to changes in their physical environment [21][22][23][24]. Previous research has indicated that the survival of walleye pollock in the early life stages can influence recruitment success in various regions [25][26][27][28].…”

Section: Introductionmentioning

confidence: 99%

Severe reduction in spawning days and larval abundance of walleye pollock under future warming in the western East/Japan Sea

Kim,

Lee,

Kim

et al. 2024

Environ. Res. Commun.

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The collapse of walleye pollock catch in the Korean fishing region during the late 1980s remains unresolved despite enormous efforts to recover its stock. To investigate the future fate of walleye pollock in the western East/Japan Sea (EJS) in the late 21st century, we implemented a dynamical downscaling approach by developing high-resolution regional ocean climate models (1/20°) with the selected Coupled Model Intercomparison Project 6 (CMIP6) global climate models. We analyzed the changes in the spawning area and larval distribution of walleye pollock in the western EJS. Under the SSP5-8.5 global warming scenario, the suitable spawning period ratio of walleye pollock was drastically reduced by 76%. The severe reduction in spawning grounds in the western EJS was mainly attributed to ocean warming caused by a decrease in atmospheric surface cooling. Moreover, our particle tracking experiment showed substantial loss of eggs and larvae south of 38°N. Our study projected a drastic collapse of walleye pollock in the western EJS and proposed a variety of collapse patterns based on local circulation under future warming conditions. These findings can help the local fishing industry adapt and assist neighboring governments in planning future fisheries management strategies.

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“…And in Japan [15,16], Alaska [17,18] was carried out eggs development and hatching of pollock's fertilized eggs related with temperature. The tendency was similar with our results as size, developmental shape and hatching time and so on.…”

Section: Naturally Collection and Development Until Yolk Absorption Omentioning

confidence: 99%

Naturally Collection and Development until Yolk Absorption of Domestic Walleye Pollock Theragra chalcogramma Fertilized Eggs and Larvae

Joo-Young¹,

Kwon²

2017

Journal of the Korea Academia-Industrial cooperation Society

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We collected and reared Theragra chalcogramma walleye pollock brood-stock for use in natural spawning tests and undertook to obtain domestic pollock via fertilized egg capture, development of fertilized eggs, and absorption of yolk sac after hatching. Whole pollock were caught with trammel and set nets and immediately placed in a deep-sea water tank. Adults were the most common pollock age group (43.0%; n = 86) among the 254 pollock captured in March 2014 with 57.9% (n = 147) being captured off Southern Gosung, Korea. The main spawning period of pollock is February (spawning phase of 91% of pollock). From the deep-sea tank, we collected 1640 mL of naturally fertilized eggs (~820,000 eggs) from 12 spawning events occurring between February 4 and 22 2015. The floating/ live eggs were maintained in deep-sea water tanks at 5.5 ± 0.2℃. Egg size was 1.5 ± 0.03 mm. Six hours after fertilization the eggs were at the 2 cell stage, and the eggs hatched approximately 340 hours after collection. At hatching, larval length and yolk sac area were 5.2 ± 0.25 mm and 9.5 ± 1.00 mm2 (100%), respectively. Four days after hatching, the yolk sac area was 2.2 ± 0.53 mm2 (23.1 ± 5.55%). This is the first report of collection of naturally fertilized eggs from pollock and their subsequent hatching while held in an indoor deep-sea water tank. The results suggest that such collection could assist in the recovery of pollock resources and the possibility of domestic rearing of cultivated larvae.

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Abstract: Bulletin of the Japanese Society of Scientific Fisheries 50•@ (6), 937-942 (1984) * Funka Bay sample ** All hatched larvae seemed normal where no figures were given.

Cited by 29 publications

References 0 publications

Effect of egg size on the growth rate and survival of wild walleye pollock Gadus chalcogrammus larvae

Effect of egg size on the growth rate and survival of wild walleye pollock Gadus chalcogrammus larvae

Severe reduction in spawning days and larval abundance of walleye pollock under future warming in the western East/Japan Sea

Naturally Collection and Development until Yolk Absorption of Domestic Walleye Pollock Theragra chalcogramma Fertilized Eggs and Larvae

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