Mariculture Fisheries Research Institute

Muroran, Japan

Mariculture Fisheries Research Institute

Muroran, Japan
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Suzuki K.,Hokkaido University | Nakaya M.,Hokkaido University | Yoo H.-K.,National Institute of Fisheries Science | Matsuda T.,Mariculture Fisheries Research Institute | Takatsu T.,Hokkaido University
Nippon Suisan Gakkaishi (Japanese Edition) | Year: 2017

To assess transportation in the early life history stages in the flathead flounder Hippoglosoides dubius, we measured the specific gravities of the eggs at 9°C and the larvae and juveniles at 9°C and 12°C using densitygradient and density-bottle methods. We also examined the effect of temperature (1, 3, 6, 9, and 12°C) on the duration between fertilization and yolk sac absorption. Eggs in glass beakers had lower specific gravities than the water densities experienced in one of the spawning grounds, Funka Bay. In contrast, the specific gravities were higher than the water densities in Funka Bay in yolk sac larvae, almost the same in early preflexion larvae, and increased with advancing development from the late preflexion larval to juvenile stages. The duration from fertilization to yolk sac period decreased with increasing water temperature. Thus, annual variation in the water temperature in the field combined with transport directions and speeds at various depths may affect the transportation of flounder eggs and larvae.

Marannu S.,Hokkaido University | Nakaya M.,Hokkaido University | Takatsu T.,Hokkaido University | Takabatake S.-I.,Mariculture Fisheries Research Institute | And 2 more authors.
Fisheries Research | Year: 2017

We investigated the relationship between morphological development in the embryonic stage and the formation of otolith microstructure in Arabesque greenling Pleurogrammus azonus, and then validated that the otolith increments were formed on a daily basis. Increments were more consistent to count and measure in sagittal otoliths from wild caught larvae compared to lapillar otoliths, and we suggest that sagittal otoliths as suitable for otolith microstructure analysis. This study clarified the formation time of three prominent increments on the sagittal otolith. First prominent increment (approx. 17 mm in otolith radius (OR)) was coincident with the time of eye-pigmentation in the embryonic stage. Second (approx. 36 μm OR) was considered to be the hatch increment and the third (approx. 38 μm OR) was at the time of transition from endogenous to exogenous nutrition. The third prominent increment which was the clearest radius (termed below as the check) was used as the starting point for validating the daily increment formation in sagittal otolith, and also there was no significant difference in the check radius among reared (6, 8, and 10 °C) and wild caught larvae. The relationship between number of days after hatching and the number of increments formed after check was significant and the slope of the regression line was not different from 1, validating the assumption that growth increments are formed on a daily basis in sagittae of P. azonus. The check was formed on the otolith at the transition from endogenous to exogenous nutrition, and the number of days required prior to its formation varied with water temperature. For the species in which the check is formed at the nutritional transition from endogenous to exogenous feeding, the relationship between number of days to check formation and water temperature is essential to estimate the hatch date of wild caught individuals. © 2017 Elsevier B.V.

Kayaba T.,Research Planning Division | Wada T.,Fukushima University | Murakami O.,Mariculture Fisheries Research Institute | Kamiyama K.,Fukushima | And 2 more authors.
Fisheries Research | Year: 2016

The conservation and management of heavily exploited fish stocks require reliable data on various aspects of reproduction. In particular, information about spawning migration and spawning period of both sexes is essential for protecting important spawning habitats. However, studies that focus on male spawning ecology are very limited. We elucidated the male spawning migration, core duration of reproduction, and seasonal changes in the maturity of the barfin flounder . Verasper moseri, an important target flatfish for stock enhancement programs in Japan. We conducted histological observations of the testes and utilized the sperm duct volume index to facilitate accurate determination of the male spawning period. Fish before spermiation were mainly observed off Hokkaido and partially off northern Tohoku (40.2-43.4°N) during August-December. However, fish undergoing spermiation and sperm release were not found near these areas and were observed only off southernmost Tohoku (35.8-37.5°N approximately 300. m deep) from late January to April. Very few spent fish were caught off southern Tohoku, but were frequently observed off Hokkaido during May-June. These results demonstrate that male . V. moseri repeat widespread spawning migrations over 700. km between feeding grounds off Hokkaido and spawning grounds off southern Tohoku. Moreover, a combined analysis related to seasonal variations in the sperm duct volume and the proportion of spawning adults identified that the core duration of male reproduction was during March. Until now, reproduction of the next generation in the wild has not been confirmed, despite the continual release of seedlings and local fishery restrictions around Hokkaido. Our results underscore the necessity of a more widespread fishery management plan for . V. moseri that encompasses the waters off Hokkaido and Tohoku to more effectively enhance reproduction. © 2016 Elsevier B.V.

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.

Shida O.,Central Fisheries Research Institute | Mihara Y.,Central Fisheries Research Institute | Mutoh T.,Mariculture Fisheries Research Institute | Miyashita K.,Hokkaido University
Fisheries Science | Year: 2014

The southwestern Pacific coast of Hokkaido is the main spawning ground for the Japanese Pacific stock of walleye pollock Theragra chalcogramma. A commercial gillnet fishery targeting spawning adult pollock in this area mainly operates from October to January to coincide with the migration of adult pollock from the feeding ground. Given the results of acoustic surveys, and changes in the proportion of the monthly total catch that was monthly walleye pollock caught by the commercial gillnet fishery, it is thought that the timing of walleye pollock spawning migration to the Donan area varies among years and that the pollock catch of the gillnet fishery clearly reflects changes in pollock abundance in this area. A time series of interannual variability in catch data from 1980 to 2005 suggested that adult pollock migrated and concentrated on their spawning ground later in the 1980s and after 2000 than in the 1990s. Such decadal-scale shifts are presumably caused by climatic changes (e.g., in water temperature) in the Oyashio region. These shifts affect the gillnet fishery through differences in monthly unit prices of pollock and changes in the formation of fishing grounds. These scientific findings can aid the establishment of rules for more efficient walleye pollock resource management under the total allowable catch system. © 2014 The Japanese Society of Fisheries Science.

Kawauchi Y.,Hokkaido University | Chimura M.,Hokkaido National Fisheries Research Institute | Mutoh T.,Mariculture Fisheries Research Institute | Watanobe M.,Hakodate Fisheries Research Institute | And 2 more authors.
Fisheries Science | Year: 2014

We examined factors affecting the vertical distribution of juvenile walleye pollock during "the second critical period" (i.e. the transition period of prey size) in and around Funka Bay, Hokkaido, Japan. During the day, small juveniles (<30 mm) were distributed mainly in shallow, warm, and low-salinity water within the bay, whereas larger ones (≥30 mm) occurred in deeper, cold and saline water. During the night, the large juveniles migrated to shallower depths. Outside the bay, small- and large-sized juveniles were distributed in water masses of similar physical properties during the daytime, whereas during the nighttime, most of the juveniles moved to shallower depth, and some juveniles dived to deeper water mass. Dietary analysis revealed that large juveniles fed on large copepods (≥0.5 mm in body width) more than small juveniles did. The composition of zooplankton in our survey area showed that large-sized copepods often occurred in deeper saline water. From these results, there is a possibility that juvenile pollock inside and outside Funka Bay occupied different water masses preferable for each feeding advantage. © 2014 The Japanese Society of Fisheries Science.

Haga Y.,Tokyo University of Marine Science and Technology | Kondo H.,Tokyo University of Marine Science and Technology | Kumagai A.,Tokyo University of Marine Science and Technology | Satoh N.,Mariculture Fisheries Research Institute | And 2 more authors.
Aquaculture | Year: 2015

Cysteine sulfinic acid decarboxylase catalyzes reaction of decarboxylation of cysteine sulfinic acid into hypotaurine. This step is considered as a rate limiting step of taurine biosynthesis in animals. Because of lower CD activity, marine fish has limited ability of de novo taurine synthesis and requires taurine in food. However, if we can develop a method to control CSD activity in marine fish, supplement of taurine to diet of marine fish is not necessary. In order to develop this technique, we have to isolate CSD from marine fish. This study, thereby, is conducted to isolate CSD from red sea bream Pagrus major and yellowtail Seriola quinqueradiata. We also analyze the expression of CSD in red sea bream, yellowtail, Japanese seabass Lateolabrax japonicus, and barfin flounder Verasper moseri. Total RNA was extracted from liver of red sea bream and yellowtail. Primers are designed against sequence of highly conserved region of reported CSD in other animals for RT-PCR. 776. bp and 725. bp partial CSD sequences were successfully cloned from red sea bream and yellowtail. By 5' and 3' RACE methods for cloned partial CSD sequences, total length of CSD (1882. bp and 1821. bp) from red sea bream and yellowtail was determined. Classification of deduced amino acid sequence revealed that red sea bream and yellowtail CSD showed 88.8% homology similar to Nile tilapia, platyfish, etc. Domain analysis shows that pyridoxine binding region was conserved in CSD from both species.Expression analysis of CSD from red sea bream, Japanese seabass, barfin flounder and yellowtail indicated that CSD is expressed in a variety of tissues but commonly in the liver and pyloric ceca of all species examined. Additionally, strong CSD expression was observed in the heart in all species examined except for Japanese seabass. © 2015 Elsevier B.V.

Joh M.,Abashiri Fisheries Research Institute | Matsuda T.,Mariculture Fisheries Research Institute | Miyazono A.,Abashiri Fisheries Research Institute
Journal of Fish Biology | Year: 2015

Otolith microstructure of reared and wild cresthead flounder Pseudopleuronectes schrenki larvae and juveniles was used to investigate the daily periodicity of ring formation, morphological change and unique otolith structure related to important life events. By comparing microstructural features of P. schrenki with those reported for other flatfish species, it was shown that there may be microstructural features that are common to all flatfishes. In the sagittae and lapillus, a check (a distinct ring) was formed in the centre of otoliths at c. 6 days post hatching, and the daily formation of rings observed outside the check was confirmed. During metamorphosis, accessory primordia (AP) of otolith growth were formed on the outer edge of the sagittae, and the shape of the sagittae became more complex. No AP was formed on the lapilli, however, and otolith rings were concentrically formed throughout the larval and juvenile (≤51·6 mm standard length, LS) stages. It is proposed, therefore, that lapilli are more appropriate than sagittae for analysis throughout the larval and juvenile (≤51·6 mm LS) stages. During metamorphosis, unique rings that are relatively wide and show weak contrast are formed on lapilli (metamorphosing zone, MZ). Hence, the duration of metamorphosis, larval duration and the days of juvenile life can be estimated by the number of rings within the MZ, using rings from the check to outermost ring of the MZ, and that of rings formed outside MZ, respectively. The formation of AP on sagittae as well as the absence of AP, bilateral asymmetry and the formation of a unique structure during metamorphosis on lapilli have also been reported for other flatfishes. © 2014 The Fisheries Society of the British Isles.

Yoshikawa N.,Kyoto University | Matsuda T.,Mariculture Fisheries Research Institute | Takahashi A.,Kitasato University | Tagawa M.,Kyoto University
General and Comparative Endocrinology | Year: 2013

Barfin flounder larvae exhibit unique black coloration, as well as left-right asymmetry in juvenile stage as in other flatfish. In this study, we first assessed the changes in melanophores with development and then investigated their responsiveness to melanin-concentrating hormone (MCH) during metamorphosis. Larval-type melanophores appeared on both sides of the body before metamorphosis, whereas adult-type melanophores appeared only on the ocular side after metamorphosis. Even in the individuals of this species displaying black coloration, the density of larval-type melanophores was similar to that in transparent larvae of other species. However, unlike in transparent larvae, larval-type melanophores completely dispersed in the black larvae of this species. Therefore, the black coloration during larval stages was mainly due to dispersion, and not the density, of larval-type melanophores. In vitro MCH treatment revealed, for the first time, the responsiveness of melanophores in larval stages. On the ocular side, larval-type melanophores aggregated against MCH during larval stages, while, in the larvae at later metamorphic stages and in juveniles, larval-type melanophores did not aggregate, although aggregation of adult-type melanophores was noted. In contrast, on the blind side, the responsiveness of larval-type melanophores to MCH was consistently present from larval to juvenile stages. The metamorphic transition of MCH responsiveness from larval- to adult-type melanophores only on the ocular side suggests the larval (therefore, immature) nature of the blind side skin. We propose that the inhibited development, and thus the retention of the larval-type skin leads to the formation of the blind side characteristics and is the central mechanism for the flatfish asymmetry. © 2013 Elsevier Inc.

Takeshita F.,Nagasaki University | Tamura R.,Mariculture Fisheries Research Institute
Fisheries Science | Year: 2014

Juvenile red king crabs (RKCs) Paralithodes camtschaticus have a strong tendency for cannibalism, which is an obstacle for seedling production. We investigated the effects of density-dependent cannibalism on the survival rate and on growth, and estimated the optimal stocking density. Four different stocking densities of juvenile first instar crabs were maintained in tanks (50, 100, 200 and 400 individuals per 100-l tank: bottom area was 0.25 m2) during the 209 or 216 days of rearing. The survival rate was affected by stocking density, elapsed days, and the interaction between these variables. Although carapace length, an index of body size, was also affected by density, elapsed days, and the interaction between these variables, the effect associated with density was quite small, suggesting that cannibalism did not intensely affect growth of juvenile crabs. We then estimated the initial stocking density that maximizes the number of survivors using parameters of analyses. Optimal initial stocking density was predicted as 416, 197 and 149 individuals per tank when the target size was assumed as 5.0, 10.0 and 15.0 mm, respectively. This estimation provides a baseline for seedling production in RKCs and could be further improved by considering other factors that affect survival and growth of RKCs. © 2014 The Japanese Society of Fisheries Science.

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