Batch fecundity (BF) of Japanese anchovy was estimated by analysis of ovarian egg size frequency around Miura Peninsula, in April through June in 1982 (a ‘warm’ year) and in 1984 (a ‘cold’ year). Total number of yolked eggs in an ovary (NT) increased with body size, showing variability in relation to GI. In 1982, the mean of relative NT (NTR=NT/SL³×10³) ranged from 22600 to 29400 with a maximum in May. In 1984 markedly lower values of 14500 in May and 16000 in June were observed. Estimated mean±S. D. of relative batch fecundity (BFR=BF/SL³×10³) in 1982 was 3400±900 in April, 7700±2300 in May, and 8400±2000 in June. These values were lower in 1984 than the same months in 1982, as 3400±1500 in May and 6500±2000 in June. The mean of BFR increased with increasing sea surface temperature (SST), showing a regression of BFR=-11200+910×SST. We suggest that sea water temperature controls anchovy egg production, as large eggs in fewer numbers occur at low temperatures and higher numbers but smaller eggs at higher temperatures. Batch fecundity varied, showing high values with high NT and GI in May 1982. In 1984, batch fecundity was reduced by the enlarged size of eggs of both egg groups which was influenced by the extremely low temperatures.

View full abstract

This paper proposes a mathematical model correlating the realized catchability coefficient with the theoretical one in random operation and stock abundance, based on the assumption that fishery preferentially exploits stocks in abundant areas. The catchability coefficient in year t, q_t is given by q_t=q(μ_t/λ₀)(N₀/N_t) or q(μ_t/λ_t)(N'_t/N_t). Here, q, μ_t, λ_t, , N_t, and N'_t are respectively the theoretical catchability coefficient, stock density exploited at t, mean density of stock at the beginning of the fishing season at t, stock size at t, and stock size at the beginning of t. Assuming gamma distributions for the initial stock density, the functional relationship between (μ_t/λ₀) and N₀/N_t and that between (μ_t/λ_t) and N'_t/N_t are derived. Numerical examinations showed that the initial geographic distribution of the stock density and its changes due to fluctuation of the stock abundance caused the variability in the catchability coefficient. The model was applied to the Japanese longline fishery which exploits the southern bluefin tuna, Thunnus maccoyii. The estimations were conducted under each of five different conditions. The values of the coefficient of determination from the q_t estimates using the first equation of q_t ranged from 0.82 to 0.92. The applications and the modifications for the model were discussed.

View full abstract

Age and daily growth of Hypoptychus dybowskii collected periodically off Usujiri, southern Hokkaido, June 1993 to June 1994, were investigated using otolith-increment counts. Daily increment formation was verified by comparing the number of increments formed after alizarin complexone marking with the number of days after treatment. Most growth occurs during the first 6 months from hatching. The relationship between standard length and the number of daily growth increments was best fitted to a Logistic curve for male, and a Gompertz curve for females:
(males) Lt=56.25/(1+exp^{-0.034(t-68.00)}) and
(females) Lt=63.16exp^{-exp-0.018(t-54398)}
No specimen had more than 365 increments in its sagittae, suggesting this species has a life span of one year.

View full abstract

The composition of visual pigment of ayu caught in the sea, a river and lake Biwa was investigated. Ayu has two kinds of visual pigment, rhodopsin and porphyropsin, with estimated λ_max of 503 nm and 528 or 529 nm, respectively. It was found that rhodopsin dominated in the retina during their sea lives, while conversely porphyropsin was dominant in the retina during their freshwater lives. In the landlocked ayu, rhodopsin was dominant throghout the year.
It is suggested that the spectral sensitivity of amphidromous ayu changes between λ_max of rhodopsin and λ_max of porphyropsin, whereas that of landlocked ayu tends toward the short wavelength side of λ_max all the year round.

View full abstract

Chimeric fish were produced by exchanging the upper halves of blastoderms at theblastula stage between goldfish-common carp hybrids with pigmented scales and goldfish with clearscales, or between goldfish with clear scales and triploid crucian carp with pigmented scales. Blastoderm transplantation was carried out in Ringer's solution containing 1.6% albumen within one minute after isolation of the blastoderm. In the absence of albumen, the transplantation was not successful. The larvae and young fish were confirmed to be chimeric fish, as transplanted blastoderm cells could be detected histologically and as the fish exhibited phenotypes typical of both fish used to produce the chimeras. Blastomere mixing between the upper exchanged and lower halves of blastoderms occurred but notto a great extent, and transplanted cells from the upper halves of blastoderms labeled with biotin were mainly distributed in the head region.

View full abstract

The objectives of this study is to compare growth, feed efficiency, and chemical composition of juvenile flounder Paralichthys olivaceus fed live mysids and formula feed under laboratory conditions. Four rearing experiments (9 to 10 days), using four different size fish, were conducted at four different constant temperatures (13, 16, 19, and 22°C). Temperatures used in the present study were chosen according to those at the nursery ground in Wakasa Bay during spring and early summer. Fish were fed live mysids or formula feed during experiments. Fish fed live mysids showed always higher growth rates in length (1.04-2.09 times in expts. 1-4) and weight (1.14-2.65 times in expts. 3 and 4), better feed efficiency (1.56-4.34 times in expts. 3 and 4) than those fed formula feed at any temperatures. Chemical compositions (proximate composition and fatty acid profile) of fish at the end of experiments reflected those of diets, and those of fish fed live mysids were nearly the same as those of wild juveniles.

View full abstract

We used loach Misgurnus anguillicaudatus sperm to study the effect of the electroporation conditions for fish sperm on the capacity of transferring a foreign gene into the eggs and the development of their derivative embryos. Results showed that sperm electroporated at low field strengths resulted in a higher hatching rate and a lower abnormality rate, compared to the high field strength group. However, the success rate of gene transfer of the low field strength group was lower thanthat of the high field strength group. Sperm electroporated at a concentration of 175 μg/ml plasmid DNA had a higher gene transfer rate than did those at 100 μg/ml or lower. The hatching rate of embryosderived from ova fertilized with sperm treated at 250 μg/ml DNA decreased abruptly, even at a low field strength (3.5 kV). Increasing the number of pulses per cycle (up to 2¹¹) and the number of cycles (upto 12) enhanced the success rate of gene transfer. Dot and Southern blot analyses and PCR detection proved the existence of transferred DNA in embryos following sperm-electroporation. An optimal conditionof electroporation for loach sperm to obtain normal development in transgenic loach is suggested.

View full abstract

Rust was used to mark the shells of short necked clam Ruditapes philippinarum. Marking was achieved by placing the clams on a rusted testing sieve. Total iron (Fe) on marked clam shells reached more than 300 μg Fe/cm² after 17 days of treatment, and the marked clams could be distinguished from unmarked clams with the naked eye. The survival rate of the marked clams in3 marking trials ranged from 73-93%, and was not significantly different from untreated controls. Fe thickness on the marked clam shell was approximately 16 μm. Retention rate of the rust mark was 83.7% at 270 days after spread to tideland, and the clams could be distinguished from non-marked clams. The rust marking can be used to investigate clam populations, since it has a long retention period, high survival, and no adverse effect on the growth of clams. Additionally, this method has practical advantages of a simple procedure and regardless of clam size.

View full abstract

In local populations, one-way gene flow occurs during a stocking program. Using a simple recursion formula and information on genetic fitness, the genetic influence on a natural population is investigated when a one-way gene flow takes place at a constant rate. One-way gene flow alters and finally replaces the genetic composition of a natural population when hatchery stocking continues over a long period of time. In particular, if the genetic composition of the stocked individuals differs from that of the optimal one, stocking prevents maximization of population fitness. In the light of these findings we emphasize the importance of using the seeds which are closely related to the gene composition of the natural population.

View full abstract

A heliozoon was isolated from a mass culture tank for rotifers when the production of the rotifer became unstable. The green algae Chlamydomonas sp. was a more suitable food for the propagation of the heliozoon compared to Tetraselmis tetrathele, Nannochloropsis oculata and baker's yeast. When the heliozoon was placed with the rotifer, the rotifer gradually ceased to move, sank to the bottom, and finally died. 24 hours' LC₅₀ for the rotifer was about 10⁴ individ./ml.
The isolated heliozoon is free-living and has a round-shape, 10-15 μmø cell body. It has one eccentric nucleus, but in the center of the cell body there is a centroplast which radiates axonemal microtubules. TEM observations revealed that each axoneme is composed of six hexagonallyarranged microtubules. Further, no coating structure was observed on the cell surface. From thesecharacteristics, we identified the species as Oxnerella maritima. This is the first record of a heliozoon killing the rotifer Brachionus rotundiformis.

View full abstract

Migration paths of the loggerhead turtles were determined through satellite telemetry. The post nesting females returned to the East China Sea, southwestern side of Japan. As these paths were bounded on the northeastern flowing Kuroshio, two different paths were found; F-1 migrated southern off side of the Kuroshio and F-2 migrated along the northern side lying between the Kuroshioand Japan Islands. The adult male was released on January 10, 1996, from Kushimoto, southern tip ofthe Kii peninsula. It returned again in nesting season near the Kii peninsula and stayed until August.The migration path and time were referred to the sunrise and sundown hour to determine the sun compass orientation.

View full abstract

Relations among carbon and nitrogen contents, photosynthetic capacity and surface-to-volume ratio were investigated using the discs cut from sporophytes of Laminaria japonica Areschoug. The relation between the carbon and nitrogen contents was divided into three phases on the basis of two distinctive nitrogen content levels, namely the subsistent and critical values. The first phase was characterized by a positive correlation between carbon and nitrogen amounts when nitrogen level was above the critical value (2.1% of dry weight). In the second phase, when nitrogen content decreased from 2.1% to 1.3% of the subsistent content, the correlation between carbon and nitrogen levels was negative. During the last phase, when the nitrogen content decreased below the subsistent value, carbon accumulation stopped. On the contrary, the photosynthetic activity of sporophytes under optimal conditions was severely suppressed when the nitrogen content fell below the subsistent value. Nitrogen levels above the subsistent value resulted in the linear increase in photosynthetic activity. In addition, the surface-tovolume ratio was correlated to the photosynthetic activity. These results indicate that photosynthetic capacity, carbon content and tissue size are linked to the nitrogen status, thussuggesting that the critical and subsistent nitrogen contents are helpful indicators for elucidating the productivity of sporo-phytes.

View full abstract

Physiological responses of yellowtail to fatal environmental hypoxia were compared to those found during Chattonella exposure in normoxia, in order to clarify the roles of blood Po₂ drop in fish kill mechanism by C. marina. Blood Po₂ immediately declined in response to a fall in water Po₂. Most of the measured variables (blood pH, hematocrit, plasma ions, heart rate, blood pressure, ventilatory frequency) did not change until blood Po₂ was decreased to 30-40mm Hg. In contrast, ventilatory pressure was increased at a blood Po₂ of 80mm Hg. Responses in most variables to fatal hypoxia were indistinguishable from those observed when fish were killed by exposure to C. marina. However, plasma chloride concentration was increased to higher levels in fish killed by C. marina than in fish subjected to hypoxia at the lowest blood Po₂ levels, implying dysfunctioning of chloride cells by C. marina. Increases in hematocrit and ventilatory pressure in response to lowered blood Po₂, were attenuated in fish killed by C. marina. Overall, we suspect that the fall in blood Po₂ played a crucial role in fish kill mechanism by C. marina, at least under our experimental conditions, and most other physiological disorders were secondarily brought about by the Po₂ drop.

View full abstract

Two strains of birnavirus were isolated from Agemaki (jack knife clam) Sinonovacula constricta originating in the Ariake sea, Japan, and from imported shells from Korea. The genome sequence of the VP 2/Ns junction regions of virus genome revealed that the 2 strains are verysimilar to each other and also similar to other birnaviruses isolated from several marine fishes. Routine survey of the virus genome from Agemaki by PCR was performed in 1993 and 1994. The birnavirus genome was detected in high ratios using samples recollected from several fishing grounds where Korean shells were transplanted. The imported shells from Korea also possessed the virus genome. These findings suggest that birnavirus is widely present in Agemaki in the Ariake sea and on the Korean coast.

View full abstract

The upward fluxes of phosphate across the overlying water-sediment interface were evaluated by three different methods. In method I, the fluxes were estimated from vertical profiles of interstitial phosphate concentrations, followed by the diagenetic model (Fick's law). Measurment of fluxes in method II was based on the changes in phosphate concentrations of overlying water in the core tubes incubated under simulated in situ dissolved oxgen conditions, and in method III, phosphate release was measured during the incubation of overlying water with surface sediments in glass bottles under dark conditions at three different temperatures. The fluxes determined by these threemethods agreed well with each other. It was considered that during the summer period, in situ fluxesin our study area might reach almost the potential level. Moreover, it was evident that the flux was influenced by ambient temperature under anaerobic condition.

View full abstract

Seawater tolerance of newborn guppies was measured by way of survival rates 24h after transfer to seawater. The newborn guppies showed high seawater tolerance and some of themsurvived in 35 ppt seawater. Seawater tolerance significantly decreased within 5 days after birth and then became stable at a level comparable to adults. After a challenge test with 35 ppt seawater at birth, the surviving individuals remained alive more days and grew in 35 ppt seawater. They yielded offspring, and most of their progeny survived in 35 ppt seawater. Therefore, the guppies could propagate in seawater and a seawater-tolerant strain was established.

View full abstract

We examined peritoneal cells of 16 marine teleost species to examine whether unique peritoneal cells observed in red sea bream are present in other marine teleosts or not. Thecomponents of peritoneal cells were divided into four types; I) consisted only of macrophages; II) two kinds of cells, macrophages and heterophilic granulocytes; III) three kinds of cells, macrophages, heterophilic granulocytes, and unclassified large round cells (large cells); and IV) four kinds of cells, macrophages, heterophilic granulocytes, large cells, and small cells with pyknotic nuclei. The group of type I included Japanese whiting, yellowtail, and Japanese conger. Group II included sea bass, rabbitfish, greenling, Japanese flounder, and filefish. Group HI consisted of red sea bream, wrasse, mackerel, common Japanese goby, and kitefin dragonet. Group IV included black sea bream, silver bream, and flathead. Small cells of flathead had a similar morphology to lymphocytes, when examined electron microscopically. As the large cells of group III and IV varied widely in morphologies, especially in nuclei and granules, we could not categorize the ‘large cells’ into a single cell type.

View full abstract

A cDNA clone for Japanese flounder (Paralichthys olivaceus) transferrin (Tf) wasisolated from a liver cDNA library. The 2, 296-bp Japanese flounder Tf cDNA sequence includes an open reading frame of 2, 055 bp and the 5' and 3' noncoding regions. The deduced amino acid sequenceof Japanese flounder Tf shares 63.3% identity with that of medaka Oryzias latipemsm and 59.5%, 59.4%, 50.5%, 43.0%, and 45.2% identities with those of Atlantic salmon Salmo salar, coho salmon Oncorhynchus kisutch, Atlantic cod Gadus morhua, Xenopus laevis and humans, respectively. The Japanese flounder Tf sequence has the duplicated structure and the conserved iron binding and cysteine residues that are characteristic of the Tf family. The TF gene was transcribed only in the liver tissue.

View full abstract

A histological study was made to determine the identity of the animal which was struck by a jetfoil (rapid-transit boat) operating for the Sado Line in the Sea of Japan, on 31 October, 1994. The material examined, a hairless mass of red and white muscle, 193 g in weight, was found in the left intake pipe of the boat. Histological examination revealed pieces of bone, comprising compact and spongy components, between the muscle fibers and tendon. The bone, lamellar in nature, included many cavities containing osteocytes. A single type of muscle spindle, comprising 9 intrafusal fibers, in association with myelinated nerve bundles, was observed. These indicated that the animal struck by the jetfoil was a cetacean.

View full abstract

A method based on reverse transcription (RT)-polymerase chain reaction (PCR) wasestablished for detection and identification of infectious hematopoietic necrosis virus (IHNV). A set of primers was prepared for amplification of a 510 bp nucleotide which encodes a region of IHNV nucleoprotein (N) gene. The PCR product was confirmed as the IHNV specific nucleotide by southern hybridization with an oligonucleotide probe synthesized from the N gene. The PCR was able to amplify the target sequence from five representative strains of IHNV from Japan and North America. There was no PCR product from five other fish rhabdoviruses. Viruses from ovarian fluid of masu salmon collected at Shibetsu River, Ichani River in Hokkaido and kidney tissue of rainbow trout in Aichi Prefecture were isolated and identified using the RT-PCR.

View full abstract

The cholesterol requirement of the freshwater prawn Macrobrachium rosenbergii, in terms of daily requirement (mg cholesterol/kg body weight/day), was assessed by the feeding experiment using casein-based diets with graded levels of supplemental cholesterol and by the analysis of carcass cholesterol. The prawn grew on a diet without supplemental cholesterol, and the body cholesterol was increased even in the prawn fed a cholesterol-free diet. However, the highest weight gain was obtained on the diet with 0.1% supplemental cholesterol. These results indicated that thejuvenile M. rosenbergii was capable of de novo cholesterol synthesis in contrast to other prawn species but required a dietary source of cholesterol for the maximum growth. When the diet containing 0.1% supplemental cholesterol was given to the prawn, it was suggested that dietary cholesterol was retained in the body at the rate of 0.065mg/g body weight/day and the apparent body retention efficiency of dietary cholesterol was 83%. Based on the above results, when true feeding levels (or % ingestion of diet) are 7 to 3% of body weight, optimum dietary cholesterol levels for the juvenile M. rosenbergii are suggested to be 0.11 to 0.26% in diet under the experimental conditions adopted.

View full abstract

Lipid components of two species of sand lance Ammodytes hexapterus and Ammodytes personatus caught in the region east of Cape Soya, in July and September 1989, were compared. The total lipid contents in whole body, muscle and viscera of Ammodytes personatus were 8.7-12.0%, 6.8-7.3% and 37.6-45.3%, respectively, and those values were higher than those from A. hexapterus (4.7-7.4%, 2.8-4.3% and 5.7-17.3%, respectively). By contrast, the values of gonad somatic index (GSI: gonad weight/body weight×100) of A. personatus (males: 0.3 and females: 0.3-0.4) were lower than those of A. hexapterus (males: 2.2-11.0 and females: 2.0-4.6).
Fatty acids of more than 1% were 14:0, 16:0, 18:0, 16:1 (n-7), 18:1 (n-9), 18:1 (n-7), 20:1 (n-ll), 20:1 (n-9), 22:1 (n-ll and n-13), 20:5 (n-3) and 22:6 (n-3). The contents of monoenoic acids such as20:1 (n-11), 20:1 (n-9) and 22:1 (n-11 and n-13) in total lipids of whole body as well as muscle were higher in A. personatus than in A. hexapterus.

View full abstract

Lipid profiles were compared between Artemia nauplii enriched with fish oil triacylglycerols (TG) containing docosahexaenoic acid (DHA, 22:6n-3) in different positional distribution patterns. Four fish oils were selected on the basis of the positional distribution determined by a nonenzymatic analytical method, and directly given to Artemia nauplii in the form of oil emulsions. Time-courses of the lipid contents, lipid compositions, and fatty acid compositions were not so different between the nauplii enriched with tuna orbital and bonito head oil TG, in which 22:6n-3 (22.9-24.0%) was esterified in the sn-3>sn-1_??_sn-2 positions and the sn-3_??_sn-2=sn-1 positions, respectively. In both of the enrichments, the level of 22:6n-3 initially not detected reached a plateau (3.4-3.6% of totalfatty acids) after 12h and then decreased to 1.7% (48h). Slight differences were also observed between thelipids of nauplii fed on sardine (22:6n-3, 11.5%; sn-2_??_sn-3>sn-1) and seal (22:6n-3, 7.6%; sn-3>sn-1>sn-2) oil TG. The levels of 22:6n-3 after 24h enrichment were 0.4% of total fatty acids. Such similarities of the lipid profiles in Artemia nauplii indicate that the positional distribution of 22:6n-3 in dietary TG has practically no influence to enrichment of Artemia nauplii with this fatty acid. It is probable that any TG with different positional distribution patterns of 22:6n-3 can be used for enrichment of Artemia, when 22:6n-3 is concentrated in the TG at an adequate level.

View full abstract

Two allergens, designated as Cra gs 1 and 2, were isolated from the oyster Crassostrea gigas by gel permeation chromatography on a Sephacryl S-300, ion-exchange FPLC on a Mono Q HR 5/5, and reverse-phase HPLC on a TSKgel Phenyl 5PW-RP. Although both allergens were sepFarated from each other by ion-exchange FPLC, they showed the same behaviors in gel permeation chromatography and reverse-phase HPLC. In addition, Cra gs were quite similar to each other as follows: they were 86 kDa glycoproteins with a carbohydrate content of about 5%; they were composed of 35 kDa subunits; they were remarkably abundant in Glx, followed by Asx, Ala, and Leu, and were devoid of Pro and Trp; their reactivities against the sera from seafood allergy patients were equivalent. The molecular masses and characteristics of amino acid composition strongly suggested that Cra gs aretropomyosin of C. gigas.

View full abstract

The sensitivity of several fish myofibrils (tilapia, carp, rainbow trout, and walleye pollack) to peroxidized triglyceride (P-TG) was compared in terms of K-ATPase decrease and myosinheavy chain crosslinking.
Upon incubation of myofibrils with P-TG, myofibrillar K-ATPase activity decreasedand myosin heavy chain cross-linking took place for all species of fish. These two changes proceeded according to the two-step first-order reactions; a quick early change was followed by a slow change. Both in the early and the later phase of the K-ATPase decrease and the myosin heavy chain cross-linking, the rate constant estimated for walleye pollack myofibrils was the greatest among the four fish species and was followed in descending rate order by rainbow trout, carp, and tilapia.
The order was in good accordance with that of the thermostability of respective myofibrils. Therefore, it was suggested that species-specific reactivity of myofibrils to P-TG was related to the structural stability of whole mvosin molecule.

View full abstract

The effect of ascorbic acid (AsA) on schooling behaviors of ayu Plecoglossus altivelis was examined using L-ascorbyl-2-phosphate-Mg as a vitamin C source. The trial using 10g size (250 fish in each tank, duplicate tanks per dietary treatment) was conducted for 36 days with testdiets containing different concentrations of AsA (0, 18, 150, and 541mg/kg diet). Schooling behavior wasobserved using the video camera system with 10 fish from each treatment after the trial.
Ayu fed a AsA-free diet did not form any schooling. Aggressive behavior, spontaneous activity, and distance to the nearest neighbors were greater in fish fed AsA supplemented diets than those fed a AsA-free diet. Particularly, fish fed a diet with 150mg AsA/kg showed the greatest value of those behavior parameters. During 36-day feeding trial survival was more than 90% and vitamin C deficiency signs were not observed in any treatment groups. The highest accumulations of AsA in both liver and brain at the end of feeding trial were found in fish fed a diet with 541mg AsA/kg.
Since the complex behavior such as schooling, being governed by tahe central nervous system, was affected by AsA intake in the present study, we suggest that vitamin C might actas the modulator of neurotransmitter in fish.

View full abstract

Seasonal variation in the level of free amino acids was investigated in the muscle and viscera of cultured small abalone Haliotis diversicolor. Among free amino acids in the small abalone, the predominant one was taurine, followed by arginine, glycine, glutamic acid and alanine. The muscle contained higher amounts of total free amino acids, taurine, arginine, and glycine than the viscera, but the latter had more glutamic acid than the former. The levels of total free amino acids, taurine, and taste-active amino acids including arginine, glycine, glutamic acid, and alanine in the muscle of small abalone sampled from October to January were higher than those from other seasons. The result of free amino acid analysis was generally consistent with the fact that the small abalone was more tasty in the autumn and winter seasons.

View full abstract

The solubility and specific ATPase activity of carp myofibrils suspended in 5 and 50mM phosphate buffer (pH 6.8) were compared at three different storage temperatures, -4, -11, and -26°C, in the absence of neutral salts throughout a period of 167 days. Allocated ATPase activities in salt-soluble and salt-insoluble fractions were also calculated from solubility and specific ATPase activity. The extent of the decrease in solubility and in the four kinds of allocated ATPase activity in the salt-soluble fraction was smaller with a decrease in storage temperature at both buffer concentrations. It is suggested that myofibril insolubilization occurred without complete inactivation of ATPase activity.

View full abstract

Carp myofibrils suspended in 5 and 50mM phosphate buffer (pH 6.8) were stored at -4, -11, and -26°C for 167 days, and the changes in volume of myofibrillar protein components in salt-soluble and salt-insoluble fractions were followed by polyacrylamide gel electrophoresis. The extents of the decrease of actin and myosin heavy chain components in the salt-soluble fraction and the increase of those in the salt-insoluble fraction were greater, and the insolubilization of those components was accelerated with an increase in storage temperature at both buffer concentrations. Under all storage conditions, there was a transient steady stage during which the changes of actin and myosin heavy chain components were very small in each fraction. The steady stages in 5 and 50mM phosphate buffers occurred at storage periods 10-89 (or 10-40) and 40-89, respectively, and especially those of the actin component in the salt-insoluble fraction were evident. The beginning of the steady stage in 5mM phosphate buffer was earlier than that in 50mM. It seems that the myofibrils were insolubilized as the actin-myosin complex in the storage range of 0-23 days at -4°C in 5mM phosphate buffer and in the range of 0-89 days under all other storage conditions.

View full abstract

The chemical components such as moisture, crude protein, lipid, mineral contents, fatty acid composition, free amino acid contents, and histologic observation of diploid and triploid amago Oncorhynchus masou ishikawae were investigated throughout the year. In October, the lipid content of triploid amago was 2-3 times as high as that of diploid. On the other hand, the moisture content in triploid was fairly low. The mean value of cross-sectional area of muscle fibers in triploid clearly increased between March and June as compared with diploid and decreased in September the same as that of diploid. No remarkable difference was seen in the protein contents, mineral contents and fatty acid composition between diploid and triploid amago.

View full abstract