This paper proposes a method for the introduction of the fishery regulation preventing the temporal reduction of catch due to the introduction. The method uses the estimates of stock abundance just before annual fishing season and introduces a new level of fishing effort or age at the first catch in the year in which the catch level is projected to increase above the recent average of the catch. Simulation studies showed that the method reduced the risk of the temporal reduction if the number of recruits in the stock is not declining, but they also indicated that the recoveries of the stock are slow. Notes in application are given and the modification of the method is discussed.

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The current morphological classification of elasmobranchs is unclear and needs refinement. This is true particularly for the relationship between sharks and rays. We determined the DNA nucleotide sequences of the mitochondrial cytochrome b gene from eight species in superorder Squalea, including eight orders of sharks and one order of rays. The molecular phylogenetic tree established from the deduced cytochrome b amino acid sequences provides strong evidence for the dichotomous classification of sharks and rays within Squalea. These results do not support the recent claim that sharks and rays are not separated into two different groups at the level of order or highertaxa. Though several cladistic studies based on morphology support the grouping of all rays into one superorder or one order, our genetic data suggest that several higher taxa are represented within rays. Alternatively, some of the higher taxa of sharks may be converged to fewer taxa.

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The biomass of anchovy Engraulis japonicus in the East China Sea and the Yellow Sea was estimated by using a quantitative echo sounder (Furuno FQ-70) combined with the analysis of midwater trawling catches. The shape of anchovy schools were calculated from echograms. The acoustic survey, conducted in May and June 1992, was executed along 7 east-west transect lines ranging from latitude 30° 00' to 35° 45' N. Trawling was made at 5 areas. Over the 5 trawling areas, 97.8% of caught fish were anchovy in the daytime, but the percentage of anchovy decreased to 67.4% at night. Anchovy behaviour differed between day and night. In the daytime anchovy compactly shoaled inmidwater or nearbottom layers with the mean packing density of 53.6g/m³. The mean vertical height and the mean horizontal width of anchovy schools in the daytime were 3.3 (±3.4, S. D.)m and 16.3 (±7.7)m, respectively. At night, they were scattered at midwater or surface water layers. The total biomass of anchovy over the survey area was estimated to be 1, 960, 000 tons using TS kg=-31.4 dB/kg (204, 289km²). Some problems inherent with acoustic method for the estimation of the biomass are discussed.

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In order to know the general features of megabenthos in Ise Bay in relation to the development and prevalence of oxygen-poor water in summer, an investigation was undertaken throughout the year from April 1993 to April 1994. Crustaceans and fishes were absolutely dominant from April to September 1993, while echinoderms being dominant since November. Five species of megabenthos were absolutely dominant: Oratosquilla oratoria (Stomatopoda), Carcinoplax vestita, Charybdis bimaculata (Brachyura), Luidia quinaria (Asteroidea), and Repomucenus valenciennei (Pisces). Community structure (e. g. species diversity, ABC-comparison, rank-abundance relationships and community type) of megabenthos in Ise Bay drastically changed with season, intimately related with development and perishment of oxygen-poor water at the bottom of the bay.

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Artificial sea bass seeds from Taiwan, which are similar to Chinese sea bass Lateolabrax sp., were morphologically and genetically compared with L. japonicus and L. sp. studied inthe previous report. Morphologically, pronounced differences were detected in many characters between L. japonicus and L. sp. Features in the characters of the Taiwanese form correspond well with those of L. sp. Genetically, a significant difference was recognized in the chi-square test for goodness of fit to the Hardy-Weinberg equilibrium at the ^*MEP and ^*PGM loci in the Taiwanese form. Furthermore, excesses of homozygotes were observed, which were presumed to be caused by genetic drift. Genetic characters indicated extreme differences in allelic frequencies at three loci between L. japonicus and L. sp. The allelic compositions at the loci in the Taiwanese form were close to those of L. sp., but differed in some other loci. This was regarded to be caused by genetic drift. The results showed that the Taiwanese form is the same species of Lateolabrax sp.

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To establish a method for identifying Porphyra species, polyacrylamide gel electrophoresis was used to examine the presence of isozymes at the growing stage from conchocelis (2 n) to leafy thalli (n). The five Porphyra species used in this experiment were P. tenera (Minomi), P. tenera (Matsukawa), P. yezoensis f. narawaensis, P. yezoensis (Saga10), and P. yezoensis (Green). The six enzymes for examining isozymes were CAT, POD, GOT, GDH, ADH, and AK. In conchocelis, the six enzymes differed with the five species. Particularly, POD and GOT were effective for separating P. tenera and P. yezoensis, and CAT and AK for identifying the tested species. POD and GOT showed the same isozyme profiles in leafy thalli and conchocelis. Other enzymes had fewer isozymes in leafy thalli than conchocelis. CAT showed no significant difference among the species, and AK was effective only for separating P. tenera and P. yezoensis.

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This study was conducted to investigate the requirements of larval yellowtail Seriola quinqueradiata for eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA) and n-3 highly unsaturated fatty acid mixture (n-3 HUFA) by feeding them with Artemia nauplii containing different levels of these fatty acids or the mixture. Fish fed Artemia enriched with a low amount of n-3 HUFA showed low growth and survival, and poor vitality. These fish displayed swimming disorders such asspinning and disorientation. The best results were obtained in larvae fed on the nauplii containing 3.9% n-3 HUFA (on dry matter basis). Elevation of DHA level in the nauplii improved survival, growth and vitality. Fish fed EPA showed poor vitality as low as those fed EFA deficient nauplii, although growth and survival were improved by supplement of EPA.
The requirement of larval yellowtail for n-3 HUFA is estimated to be about 3.9% (2.5% EPA, 1.3% DHA and others) in Artemia on dry matter basis. The requirement for DHA is estimated to be 1.39-2.63% in Artemia on the basis of larval vitality. On the other hand, it is satisfied with 1.39% DHA (2.25% n-3 HUFA) or 3.65% EPA on the basis of survival rate.

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The optimal conditions to induce androgenetic diploids using ⁶⁰Co gamma irradiation and hydrostatic pressure shock in amago salmon Oncorhynchus masou ishikawae were determined. Androgenetic haploids were produced when eggs were irradiated prior to fertilization, with an optimal dose of 450 Gray. Diploid amago salmon were produced from irradiated eggs by suppression of the first cleavage after fertilization with normal sperm. The optimal timing of the hydrostatic pressure shock (650 kgf/cm², 6min) was determined to be 7.5 hours after insemination at 10°C. DNA fingerprinting showed that the androgenetic offspring (second generation in androgenesis) were clones, thereby demonstrating that the androgenetic diploids (first generation in androgenesis) produced in these experiments were completely homozygous.

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The seawater adaptability of 0⁺ landlocked Japanese char Salvelinus pluvius was studied with mortality, gill Na⁺-K⁺ATPase activity, and serum Na concentration, in order to evaluate the possibility of culture in seawater of this fish. When the fish (35g) were transferred directlyinto seawater (the seawater challenge test), no mortality occurred even at 96h after a direct transfer. Thegill Na⁺-K⁺ATPase activity increased gradually, and the value at 96h reached 4 times higher than the initial value. Serum Na concentration increased to about 180mM at 24h after transfer and, afterwards, the level showed no increase until the end of the experiment. When the fish were reared in seawater over 100 days (the seawater rearing test), they grew from 35g (Day 0) to over 90g (Day 103). The gill Na⁺-K⁺ATPase activity at Day 103 was 9 times higher than the initial value. Serum Na oncentration at Day 103 recovered almost to the initial value. These results suggest that the fish has acquired seawater adaptability in the size of 35g and that this ability increased gradually while the fish were reared in the seawater environment. Since the fish can be transferred directly into seawater without any acclimation, it is possible to culture 0⁺ landlocked Japanese char in seawater.

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This experiment was conducted to gather some basic information necessary for thedevelopment of quality dry pellets for yellowtail broodstock. The spawning results of yellowtail broodstock fed softdry pellets (SDP) and Oregon type of moist pellets (MP) and/or frozen raw fish (RF) were compared.
Yellowtail having an average body weight of 3.7kg, which had been cultured withextruded dry pellets (EP) from juvenile stage (about 0.89g BW) for 20 months, were divided into two lots of 25 fish each and stocked into the 5×5×5m floating net cages. The first group was fed SDP containing 10% krill meal and the second group was fed MP. Yet another lot of 25 broodstock fish which had been fed EP for 14 months and subsequently fed RF for 6 months, continued to receive the same food until spawning manipulation. Egg collection was undertaken after brood fish were transferred to the 65m³ spawning tanks on land and they were induced to spawn by injecting 600 IU-HCG/kg-fish BW.
Two days after HCG injection, brood fish from SDP and MP groups started to spawnand continued for 8 and 10 days, respectively, but broodstock fed RF spawned only once during this period. The SDP group produced only half of the total number of eggs obtained from the MP group. However, the quality of eggs were found to be superior to those obtained from the MP group. Out of the total eggs produced, the percentages of buoyant and fertilized eggs and total hatch were respectively about 59, 57 and 47 for the SDP group; 39, 34 and 18 for the MP group and 36, 3 and- (not determined) for the RF group.
The preliminary results obtained in this experiment have clearly indicated that broodstock yellowtail can be cultured with extruded dry pellets from the juvenile stage under captivity. Further this would enable the development of quality dry pellets for yellowtail broodstock in the near future.

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The respiration activity of epiphytic bacteria on Eisenia bicyclis Kjellman was determined by using 2-(p-iodophenyl)-3-(p-nitrophenyl)-5-phenyl tetrazolium chloride (INT). In June and August, the percentage of active bacteria on the surface of new blades were 59.6% and 51.6% respectively and that on old blades was almost 100%. The bacterial respiration activity became low when the blades were incubated in the light. The phenol excretion rate from algal blades was high in new blades and in the light. These results suggested that epiphytic bacterial activity on E. bicyclis is suppressed by excreted algal phenols.

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The population structure and feeding behavior of the edible stomatopod crustacean Kempina mikado (Kemp & Chopra, 1921) was studied from samples captured with bottom trawls inthe East China Sea. The sex ratio (female:male) was 1.64:1. Four size-class groups were discriminated for each sex which may correspond to one to four year-old cohorts. Gut analysis showed that this animal is a typical carnivore and mainly ate the tentacular clubs of the squid Loligo edulis and fish, regardless of sex and body size. From the present data, the suspected heavy predation on commercially important penaeid prawns by K. mikado was not confirmed.

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The tubicolous polychaete, Spirobranchus giganteus lives buried in coral skeletons. Its age and longevity were estimated indirectly from the annual coral-growth rings of the host coral counted on soft X-rays radiographs. Since the polychaete tube grows 0.2 to 1mm per year in orifice diameter, some had lived more than 10 years, and a few had lived more than 40 years. The application of soft X-rays for age determination of coral associated polychaete is useful for determining the correct age.

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Two experiments were conducted to determine the effect of continuous exercise training, dietary lipid, and starvation on the growth and efficiency of feed utilization of red sea bream Pagrus major. In the first experiment, fish (2.5g) were maintained in water velocities of 0, 1.5, and 3 body lengths per second (BL/s) under satiation feeding. In the second experiment, fish (17.5g) were maintained at 0, 1, and 2 BL/s under a restricted feeding regime. The fish in both experiments were feddiets containing two levels of lipid, and after the feeding period, the fish were fasted for seven days under exercise conditions. In the first experiment, higher swimming speed negatively affected the final body weight and specific growth rate, but not feed efficiency or nitrogen retention. In the second experiment, the non-exercised fish exhibited higher feed efficiency and nitrogen retention, as well as growth rate, than did the exercised fish. The whole-body lipid content was reduced by fasting and by increased exercise, but was positively related to dietary lipid level. Swimming activity level exerted a greater effecton whole-body lipid level than either dietary lipid level or starvation.

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The characteristics of serum lipoproteins from rainbow trout were investigated using dextran sulfate cellulose (DSC) gel. The binding profiles of very low density lipoprotein (VLDL), low density lipoprotein (LDL), high density lipoprotein (HDL), and vitellogenin (VTG) to DSC gel were consistent with a simple Langmuir'sadsorption isotherm. The dissociation constants of VTG and VLDL were lower than those of LDL and HDL, suggesting high affinities of VTG and VLDL for DSC gel. VTG and VLDL were found to have specific capacities for binding to DSC gel from the values of maximum binding level. When applied to a DSC column, both unbound and bound fractions were present in VLDL and LDL. Apolipoprotein components differed in unbound and bound fractions, and apolipoprotein B-like protein of molecular weight 260, 000 (Mr 260K) in both VLDL and LDL seemed to have a high affinity for DSC gel. Taking into account that VTG which possessed apolipoprotein with Mr170K as a main component had the highest binding capacity to DSC gel, a structural similarity was strongly suggested between apolipoprotein B-like protein in VLDL and LDL and apolipoprotein in VTG.

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The postmortem changes of high energy phosphate compounds, inorganic phosphate (Pi), and intracellular pH (pHi) in the oyster tissues were investigated using non-destructive phosphorus-31 nuclear magnetic resonance (³¹P NMR) spectroscopy with a surface coil attachment. Levels of arginine phosphate (PAr), ATP, and ADP decreased faster in the adductor muscle than in the body trunk. Initial pHi in the adductor muscle, about 7.33, was significantly lower than that in the body trunk, about 7.48, although the two tissues had the same final pHi. Phosphodiesters (PDE) mainly composed of glycerophosphorylcholine were detected in both the tissues. ³¹P NMR was also used to evaluate the degree of freshness of oyster stored over a 25h period postmortem. The ratios of [PAr]/[Pi(+PDE+phosphomonoester (PME)] and [ATP]/[Pi(+PDE+PME)] and the pHi decreased rapidly and continuously during the acceptable stage, and were demonstrated as potential indices to estimate the freshness of oyster. ³¹P NMR is a powerful tool for the evaluation of freshness, because of its non-destructive, convenient, rapid, and simultaneous determination of high energy phosphate compounds, Pi, and pHi in the oyster tissues.

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The effects of casein on the gelation of walleye pollack surimi paste were investigated. When the surimi paste with or without casein was preincubated (setting) at 25°C for up to 12h, followed by cooking at 90°C for 30min, the addition of casein interfered not only with heat-induced gelation but also setting response.
The addition of 1% and 5% casein to the surimi paste decreased the myosin content by about 9% and 32% on a protein basis, respectively. Since casein did not showa composite reinforcing effect on the surimi gel, the dilution of myosin-myosin interaction may be a major cause of the inferior gelation.
Although myosin heavy chain was a better substrate for transglutaminase (TGase) than casein, casein added into the surimi paste effectively inhibited the enzyme-catalyzed myosin heavychain crosslinking, particularly depressed the formation of its large polymers (n_??_3) during the setting, and resulted in the weakening of cooked gels. A large amount of casein added to actomyosin also inhibited the TGase-catalyzed cross-linking of myosin heavy chain. TGase catalyzed the formation of hybrid proteins from a mixture of actomyosin and casein, but their amounts seemed to be too small to influence the gelling properties of the surimi paste.

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Triglyceride was predominant in lipid class of a carp muscle tissue, while sarcoplasmic reticulum (SR) and mitochondria were mainly composed of phospholipids, such as phosphatidylcholine (PC) and phosphatidylethanolamine (PE). Plasma membrane was rich in sterols (ST) togetherwith PC and PE. Fatty acid compositions of polar lipids, PC, and PE of SR were most similar to those of muscle tissue among biological membranes. Thus, SR of carp muscle is expected to be a good model for investigating phospholipid decomposition in muscle cells.

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The hemolymph proteins of the acorn barnacle Megabalanus rosa were separated by two-dimensional gel electrophoresis. More than 50 proteins were observed in the region of acidic (pl: 4-7) with masses of 18-120 kDa. The proteins separated on the gel were electroblotted onto a polyvinylidene difluoride membrane and were sequenced. Several major proteins were further characterized by amino acid analysis and peptide mapping, and identified to be multiple lectins.

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We prepared tilapia myosin rod by digesting myofibril with chymotrypsin. Subsequent digestion of the rod generated a 39 kDa light meromyosin (LMM), which could be isolated on DEAE-Toyopearl. The 39 kDa LMM had an isoelectric point of 5.5 higher than that of an ordinary LMM, 5.1. The 39 kDa LMM required no Mg²⁺ for its filament formation. These structural and filament forming proper ties of tilapia 39 kDa LMM are very similar to those of carp 40 kDa LMM. These similarities suggest that the tilapia 39 kDa LMM is derived from the carboxyl terminal end of the rodlike carp 40 kDa LMM. It was also found that the filament formed by tilapia 39 kDa LMM is more fragile than that by carp 40 kDa LMM. We therefore concluded that the filament forming ability of the39 KDa LMM is responsible for the fragile myosin filament of tilapia myosin.

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The oxidation state and its distribution of selenium in twelve blood specimens of cultured yellow tail Seriora quinqueradiata are presented in relation to the distribution of mercury and the glutathione peroxidase activity.
The concentration {Se(-II, 0, IV)} of the low oxidation state of selenium correlated positively with total selenium concentration (T-Se), suggesting that organic selenium, selenide and selenite were predominant in the blood. Total mercury concentration (T-Hg) in the blood was extremely low. Glutathione peroxidase activity (GSH-P_x) did not correlate significantly with Se(-II, 0, IV) and (T-Hg), respectively, while the activity correlated negatively with fork length of yellow tails.
These findings suggest that selenium in the blood will mainly exist as protein-containing selenohydryl groups with a trace amount of mercury and glutathione peroxidase.

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Lipids in 26 samples including the 20 species of myctophid fishes (Family Myctophidae) caught in the western subarctic and tropical Pacific Ocean were characterized. Myctophid fishes contained lipids at the level of 0.5 to 21.7% and were classified into three groups by lipid class composition, i.e., triglyceride-rich (5 species), wax ester-rich (3 species) and phospholipid-rich (12 species) groups. No fish which is rich in both triglycerides and wax esters was observed in the present study. The triglyceride-rich and wax ester-rich groups were found in the western subarctic Pacific, i.e., the Oyashio species, while the phospholipid-rich group with low-lipid content was found in the tropical species, i.e., the Equatorial and Central Water species. Three species, Stenobrachius leucopsarus, Lampanyctus regalis and Stenobrachius nannochir, contained wax esters with 30 to 44 carbon chain lengthsas the major lipids, always accounting for more than 90% of total lipids. The main alcohol moieties of wax esters were 16:0, 20:1 and 22:1, while oleic acid (18:1n-9) and other monoenoic acids were predominantly fatty acids. Lipid composition analyses suggested the tendency that wax esters are rich innon-migratory or partly-migratory species.

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Dietary fiber content, water-holding capacity, and binding of artificial colors, vitamin, and cholate were studied for 12 species of green, brown, and red algae. Hijiki contained higher soluble dietary fiber and some specimens of wakame had the highest amount of insoluble dietary fiber. High water-holding capacity of wakame seemed to be characteristic, ranging from 19 to 44g/g dry seaweed. When samples were immersed in acid water to simulate the gastric pH condition, almost all water-holding capacity of seaweeds decreased. Settling volume in water was similar to water-holding capacity, and wakame had the higher values. Susabi-nori, suji-aonori, and some specimens of wakame showeda higher capacity to bind amaranth than other seaweeds. Erythrosine and rose Bengal bound by many seaweeds were higher than amaranth. Wakame sporophyll and hijiki showed the highest percent binding (42.7-45.6%) for thiamin, but Mitsuishi-kombu and susabi-nori showed the lowest binding (8.3-10.6%). Binding of sodium cholate by susabi-nori was the highest (12.6-15.5%); over twice that bound byanother seaweeds except suji-aonori (9.7%). However Mitsuishi-kombu, ma-kombu and one hijiki had a lower binding capacity (0-2.6%).

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Walleye pollack surimi paste was incubated (set) at 25, 35, 45, and 55°C in the presence of either transglutaminase (TGase) inhibitor or protease inhibitor. In the absence of inhibitors, cross-linking of myosin heavy chains and formation of 150 kDa component occurred at the same time during the incubation at 25°C.
Inhibition of endogenous TGase resulted in complete suppression of myosin cross-linking, while it did not suppress the formation of 150 kDa component. The cross-linking was also depressed above 45°C due to the inactivation of TGase. On the other hand, the addition of E-64, a cysteine protease inhibitor, suppressed completelyand partially the formation of 150 kDa component at 25 and 55°C, respectively. Together with these results, the 150 kDa component might be a proteolytic fragment of myofibrillar proteins, possibly myosin.
The proteolysis as well as the cross-linking of myosin during the setting affected the textural properties of final cooked gels.

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When carp myosin was stored in ice, a decrease in SH content and polymerization of myosin heavy chain (MHC) through SS bonding were observed along with a decrease in Ca²⁺-ATPase activity. By adding a chelating reagent (EDTA), the decrease in SH content and the polymerization were depressed. The addition of a reducing reagent (dithiothreitol) showed that the decrease in Ca²⁺-ATPase activity occurredwithout the polymerization by SS bonding. In contrast, the polymerization of MHCwas greatly promoted in the presence of a metal ion (Cu²⁺), whereas the decreasein Ca²⁺-ATPase activity was observed at the same level as without the metal ion. The addition of cryoprotectants (sorbitol, sucrose) showed a slight depressing effect on the decrease in Ca²⁺-ATPase activity and noinfluence on the polymerization of MHC.
It was concluded that the oxidation of SH groups in myosin along withthe polymerization of MHC proceeded regardless of the conformational change in myosin head portion related to Ca²⁺-ATPase activity during ice storage. Therefore, it was suggested that the MHC polymerization during ice storage is due to SH groups on the myosin tail portion, even if myosin is free from actin.

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To clarify the role of the head and the tail portions of myosin in the dimer formation of myosin heavy chain through SS bonding during ice storage of carp actomyosin, carp myofibril and myosin digested with α-chymotrypsin to S-1 and rod were stored in ice with 2 ppm of Cu²⁺ to enhance the oxidation of SH groups.
A newly produced major substance through SS bonding was estimated to be 260K inmolecular weight, which was double the size of rod (130K). In addition, this substance was confirmed to be composed of only rod by two-step SDS-PAGE. A dimer of S-1 was not observed at all during the ice storage. Furthermore, the dimer formation of rod was also observed in the purified myosin rod solution.
It was, therefore, concluded that the formation of the dimer of myosin heavy chain during ice storage of carp actomyosin and myosin is due to the oxidation of SH groups on myosin rod, not on the myosin head.

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The elastic texture in pre-rigor fish muscle is valuable for the preparation of sliced raw fish. For the purpose of delaying the ATP degradation and the pH decrease in relation to the delay of rigor development in red sea-bream muscle during storage, spinal cord destruction was tried immediately after stabbing the medulla oblongata. In spinal cord destroyed fish muscle, the ATP level, the pH value, and the breaking strength were high at the initial stage of storage, and theirdecline was slow during storage at 3°C. The ultimate values of pH and breaking strength were high. In the case of spinal cord destroyed fish, the rigor index increment ceased temporarily and the index reached 100% at 12-19h behind the controls. The peak value of generated rigor tension was small. The high breakingstrength throughout storage was ascribed to less structure weakening of muscle because the generatedtension was small due to the delay of rigor development. The high breaking strength is also ascribed to less proteolytic breakdown of the pericellular connective tissue of fish muscle due to the relatively high pH condition.

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Feeding experiment was conducted to determine the influence of dietary phosphorus levels on growth and mineral availability to juvenile rainbow trout. Mono-basic potassium phosphate was supplemented to semipurified diet at 2, 4, 6, and 8%, in order to obtain graded dietary phosphorus (P) levels (11.7_??_29.7mg/g). Growth, PER and NPU were not influenced by the dietary P at the level of 19.7mg/g, butwere decreased by 25.1mg P/g or more. P, zinc (Zn) and manganese (Mn) contents in vertebrae were significantly lowered by the diet containing P of more than 25.1mg/g. Zn absorption was significantly influenced by the excess amount of dietary P, namely it was lowered by P at levels exceeding 19.7mg/g diet.
The study demonstrated that excess amounts of dietary P at a level three times higher than the P requirement lowered protein utilization and Zn absorption, induced poor growth andreduced Zn and Mn in the body of rainbow trout. It is suggested that the available P content inrainbow trout diet might be regulated to be less than 15mg/g.

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