Kushiro Fisheries Research Institute

Kushiro, Japan

Kushiro Fisheries Research Institute

Kushiro, Japan
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Takiya A.,Central Fisheries Research Institute | Fukushi A.,Kushiro Fisheries Research Institute
Nippon Suisan Gakkaishi (Japanese Edition) | Year: 2012

Two groups of Pacific herring Clupea pallasii juveniles, i.e., with and without intermediate culture before release, were released on the same day to clarify the damage to the juveniles during the transportation and release processes. A sudden decrease in triglyceride content, a sudden rise in acid phosphatase activity, and abnormal ring formation in the otoliths were observed in the juveniles after transportation and release. Abnormalities such as variations in swimming depth of the juveniles and abnormal feeding behavior of the juveniles were observed in the early periods after release. The damaged juveniles required approximately 5 days after transportation and more than 10 days after release to achieve recovery. Obvious differences in rates of abnormal ring formation in the otoliths in both groups suggest that the damage was more pronounced in the group without intermediate culture before release than in the group with intermediate culture before release.

Kayaba T.,Kushiro Fisheries Research Institute | Wada T.,Fukushima Prefectural Fisheries Experimental Station | Murakami O.,Mariculture Fisheries Research Institute | Sawaguchi S.,Seikai National Fisheries Research Institute | Kawabe R.,Nagasaki University
Fisheries Research | Year: 2015

For conservation and management of fish stock, reliable reproductive parameters, especially information on the spawning period, are greatly needed. Until now, the spawning period of male fish was estimated mainly using the gonadosomatic index (GSI) and microscopic observation of the testes. However, these methods pose the problem of estimation accuracy and handiness for analysis, respectively. To identify biological characteristics that would allow accurate determination of spawning periods, we investigated the seasonal development of testes and sperm ducts in our model fish, the barfin flounder Verasper moseri. GSI (testis weight. ×. 100/body weight) reached a maximum during November-December; however, this peak period occurred approximately two months before the onset of spawning. In contrast, the sperm duct index (SDI) (sperm duct weight. ×. 100/body weight) sharply rose from February to March when spermiation and sperm release actively proceeded. On comparing the SDI of all gonadal development phases, it was found that only the fish that underwent spawning had significantly enlarged sperm ducts due to sperm accumulation. This finding strongly suggested that sperm duct volume is an adequate indicator for accurately identifying spawning period in male fish. Moreover, analysis using SDI takes less effort for sample processing, suggesting to be practical for continuous monitoring of stock assessment. © 2015 Elsevier B.V.

Kayaba T.,Kushiro Fisheries Research Institute | Wada T.,Fukushima Prefectural Fisheries Experimental Station | Kamiyama K.,Fukushima Prefectural Fisheries Experimental Station | Murakami O.,Mariculture Fisheries Research Institute | And 5 more authors.
Fisheries Science | Year: 2014

Commercial catches of barfin flounder Verasper moseri, an important target flatfish for stock enhancement programs in northern Japan, have recovered remarkably since the large-scale release of seedlings from Hokkaido in 2006. However, their reproductive ecology remains unclear. Our study of 2008-2012 investigated seasonal changes in the maturity of stocked female barfin flounder (n = 4,123) off the Pacific coast from Hokkaido to Tohoku (35.7°-43.4°N). Histological observation of ovaries revealed that fish undergoing vitellogenesis were observed mainly off Hokkaido and partially off northern Tohoku during August-January (40.2°-43.4°N). However, fully matured or spawning fish were not found near those areas. They were observed only in southern Tohoku. Ongoing spawning was observed off southernmost Tohoku (35.8°-37.5°N around 300 m depth) from early February through late April, when commercial landings had decreased drastically off Hokkaido. Spent fish were caught only rarely off southern Tohoku, but were observed frequently off Hokkaido during April-June. These results demonstrate that spawning grounds form at the upper continental slope off southernmost Tohoku during February-April. Relations between maturation traits and seasonal landings strongly suggest that female barfin flounder repeatedly migrate more than 700 km from feeding grounds off Hokkaido to spawning grounds off southern Tohoku. © 2014 Japanese Society of Fisheries Science.

Gouda H.,Kushiro Fisheries Research Institute | Endo H.,Kagoshima University | Agatsuma Y.,Tohoku University
Regional Studies in Marine Science | Year: 2017

To elucidate the effects of seawater temperature on long-term recruitment of juvenile Strongylocentrotus intermedius, annual changes in the juvenile density were monitored for 25 years from 1987 to 2011 off the coast of Rebun Island in the Sea of Japan off northern Hokkaido, Japan. The densities of 8–9 month and 1 year old juveniles fluctuated greatly from 0 to 47.2 ind/m2 and from 1.2 to 79.2 ind/m2, respectively. However, the recruitment occurred frequently and the densities of 1 year old juveniles exceeded 20 ind/m2 in 1987, 1989, 1992, 1997, 2004, and 2007, indicating a high level of recruitment. Significant negative correlations between the densities of 8–9 month old juveniles and the monthly average water temperature from June to September of the previous year were detected (p <0.05). In particular, the correlation was the most significant in June (p <0.01). The densities were high (>20 ind/m2) at 10–11 °C and low (<10 ind/m2) at 12–13 °C. As a previous study indicates that the gonads develop from growth to spent stage during these months in Rebun Island, no significant increased water temperature in the northeastern Sea of Japan may be concerned with gonad maturation and spawning of adult population, leading to success in juvenile recruitment. © 2017

Kubo K.,Hokkaido University | Kubo K.,Japan Institute for Environmental Sciences | Yamaguchi K.,Japan Institute for Environmental Sciences | Mitsuhashi M.,Kushiro Fisheries Research Institute | And 2 more authors.
Marine Pollution Bulletin | Year: 2013

The concentrations of PCB congeners in the blubber and liver of male and female Steller sea lions (Eumetopias jubatus; SSLs) collected from the Shakotan Peninsula and the Nemuro Strait, Hokkaido, Japan in 2008 and 2010 were measured by HRGC-HRMS, in order to express the concentration profiles in SSLs at these regions. #153 predominated in both organs, followed by #138, #99 and #118. In males, #28 and #31 were concentrated particularly in the blubber, while #177 and #199 were accumulated specifically in the liver. The differences in these concentration profiles might be expressed by the differences in the organs and their functions. The concentrations of #99, #118, #138, #153, and #180 in the blubber appeared to correspond significantly with the differences between genders. The details of the surveys on PCB congeners in SSLs could clarify the differences in the residue levels of individual congeners for organs and genders. © 2012 Elsevier Ltd.

Narimatsu Y.,Tohoku National Fisheries Research Institute | Kakehi S.,Tohoku National Fisheries Research Institute | Ito S.-I.,University of Tokyo | Okazaki Y.,Tohoku National Fisheries Research Institute | And 2 more authors.
Canadian Journal of Fisheries and Aquatic Sciences | Year: 2015

A massive tsunami hit the north Pacific coast of Japan on 11 March 2011. We evaluated the effects of the tsunami on the distribution, growth, and survival of young Pacific cod (Gadus macrocephalus) using data from benthic trawl surveys and otolith microstructure analysis. The distribution of Pacific cod juveniles differed between 2011 and 2008-2010. The 2011 year class was smaller in body size than those in 2008-2010. The majority of 2011 year-class juveniles was captured in deeper areas at a smaller body size, whereas those of previous year classes were primarily distributed in shallower water. The peak hatch of the 2011 year-class juveniles was from early to late February, which was several days later than those of the 2008 and 2010 year classes. The 2011 year class grew at the same rate as those from 2008 and 2010 until the day of the tsunami, but had a lower growth rate during the 30 days after the tsunami, resulting in a decrease in fish size at settlement. Growth of the 2011 year class was also inferior soon after the day of the tsunami in almost all groups divided by the hatching period. Growth of juveniles captured in shallower water following the tsunami in 2011 tended to be slower than that of juveniles captured in deeper water. Our results suggest that the tsunami caused a decrease in growth rates for approximately 30 days and a change in the distribution of juvenile fish relative to prior years. The change in distribution was primarily the result of mortality in shallow water caused by physical damage and (or) subsequent decreased growth. Considering these results and the finding that the recruitment level and the recruits per spawning in the 2011 year class were low, the tsunami may have affected the determination of the recruitment level. © 2015, National Research Council of Canada. All rights reserved.

Akino M.,Kushiro Fisheries Research Institute | Aso S.,Kushiro Fisheries Research Institute | Kimura M.,Kushiro Fisheries Research Institute
Fisheries Science | Year: 2015

This paper describes a study of the use of sea urchin skeletons, a waste product of food-processing, as a biological filter medium. We obtained skeletal materials (tests, spines, and teeth) from the northern sea urchin Strongylocentrotus nudus by alkali treatment and evaluated their performance as biological filter media in an aquarium experiment. The nitrification performance was investigated in an aquarium using these skeletal materials. The results showed that the tests and spines particularly provided high ammonia oxidation performance. In addition, sea urchin skeletal materials kept the pH of the aquarium water constant at 7–8. Therefore, we conclude that the structure and components of sea urchin make them suitable for use as biological filter media. © 2015, Japanese Society of Fisheries Science.

Sato M.,Tokyo University of Marine Science and Technology | Tokai T.,Tokyo University of Marine Science and Technology | Mori Y.,Japan Fisheries Information Service Center | Nakame Y.,Kushiro Fisheries Research Institute
Nippon Suisan Gakkaishi (Japanese Edition) | Year: 2016

A drift net series consisting of several net panels of nine different mesh sizes was used to investigate pelagic fish resources in the waters off Hokkaido, Japan during June-July and September-November. This study aimed to determine the most appropriate mesh size combination of research drift net series with an approximate constant catching intensity over a large range of fish length for research on chub mackerel Scomber japonicus the resources of which are in the process of recovering. Selection curves were estimated for the mesh sizes from the data of the drift net research carried out in the two periods of June-July and September-November. Across all mesh sizes, fish caught in June-July had slightly greater fork length than those in September-November, and they also had a lower condition factor implying a smaller body girth following spawning. The pooled relative catching intensity steeply declined for fish with fork length over 300 mm at the current mesh combination, suggesting a possible underestimation of stocks of large fish. A simulation showed that the addition of two panels with larger mesh sizes (82 and 106 mm) kept a constant intensity for fish below 350 mm fork length. © 2016 The Japanese Society of Fisheries Science.

Wada T.,Fukushima Prefectural Fisheries Experimental Station | Kamiyama K.,Fukushima Prefectural Fisheries Experimental Station | Shimamura S.,Fukushima Prefectural Fisheries Experimental Station | Murakami O.,Mariculture Fisheries Research Institute | And 3 more authors.
Fisheries Science | Year: 2014

Commercial landings of a rare pleuronectid flatfish, barfin flounder Verasper moseri, recovered drastically after large-scale stock enhancement in Hokkaido conducted since 2006. This study investigated commercial landings, fishing grounds, size distributions, and sex and age compositions of barfin flounder during 2007–2011 in southern Tohoku, their major spawning ground, which is over 700 km south of Hokkaido. Landings, mostly comprising stocked fish, increased drastically in southern Tohoku: from 2.0 tons in 2007 to 20.8 tons in 2010. Over 98 % of them were landed during January–April, with the peak period during February–March. Fishing logbook data of offshore bottom-trawl vessels during 2007–2010 revealed the upper continental slope off southernmost Tohoku as the main fishing ground (35°40′–36°50′N, annual weighted mean depth 267–299 m). Two size modes in the landings consisted of males (ca. 40 cm) and females (ca. 60 cm). The main age at fishery recruitment in southern Tohoku was younger for males (age 2+) than for females (ages 3+ and 4+), the result of which was that the female percentage was lowest at 1.5 % in 2009 and highest at 7.9 % in 2011. Our results showed clearly how the effectiveness of large-scale stock enhancement in Hokkaido extended to southern Tohoku in association with spawning migration of stocked barfin flounder. © 2014, Japanese Society of Fisheries Science.

Kusaka A.,Japan National Research Institute of Fisheries Science | Shimizu Y.,Japan National Research Institute of Fisheries Science | Sato T.,Kushiro Fisheries Research Institute | Yoshida J.,Tokyo University of Marine Science and Technology
Journal of Oceanography | Year: 2016

Direct current measurements by a shipboard and bottom-mounted acoustic Doppler current profiler and concurrent hydrographic observations with a CTD were conducted off southeastern Hokkaido, Japan, between January and May 2005 to reveal temporal variations in the current structure and volume transport of the Coastal Oyashio (CO). The CO, which has a baroclinic jet structure with southwestward speeds exceeding 90 cm s−1 and a width of 7–8 km, was associated with a surface-to-bottom density front and was formed on the offshore side of the shelf break. The volume transport of CO (TCO) was estimated by integrating the fluxes of lower-density water that was trapped against the coast along the density front represented by the 26.2 σθ isopycnal line. This transport decreased monotonously from 0.79 Sv (1 Sv = 106 m3 s−1) in January to 0.21 Sv in March and subsequently to 0.12 Sv in May, possibly due to the decay of the East Sakhalin Current Water in the Okhotsk Sea. Accompanied by a decrease in TCO, the location of the jet structure associated with the density front moved toward the coast while the maximum speed of the jet decreased and the tilt of the front became more horizontal. Consequently, more saline offshore Oyashio water flowed into the deep part of the shelf area, and the current structure altered from relatively barotropic in winter to baroclinic in spring. This study is the first to estimate the observed volume transport of the CO from direct current measurements. © 2016 The Oceanographic Society of Japan and Springer Japan

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