The present report deals with the age and growth of the wrasse Halichoeres poecilopterus (Pisces: Labridae) in relation to sex types (primary male, female, and secondary male) examined by scale reading, based on fish taken from Ago Bay, Mie Prefecture, Japan from July 1977 to August 1985.
The scale removed from the ventrolateral portion of the trunk was the most suitable for age determination, and the ring marks on it were clearly distinguishable. Examination of marginal increments of scale showed that the ring marks formed once a year from January to March. The relationship between standard length (SL, mm) and body weight (W, g) was expressed by the formula: log₁₀ W=3.15 log₁₀ SL-5.00. There were no significant differences in the mean back-calculated lengths at the time of each ring formation between primary males and hermaphroditic individuals (females and secondary males). The growth curves for length and weight were de-scribed as follows: L_t=211 (1-exp (-0.224(_t+1.049))); W_t=210(1-exp (-0.224(t+1.049)))^3.15; where L_t=standard length at age t; W_t=body weight at age t. The sex change from females to secondary males in hermaphroditic individuals took place mostly at age 4 or older. The larger females have a stronger tendency to change to secondary males in a certain age group.

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In order to estimate the degree of genetic divergence between two Paratya subspecies, Paratya compressa compressa and P. c. improvisa, which are common freshwater shrimp in Japan, isozymic analysis was carried out by starch gel electorophoresis. Eighteen loci coding for 15 enzymes were scored in both subspecies. Of the 18 loci, 7 divergent loci with no common allele were observed between the two subspecies. Nei's genetic distance between the subspecies was 0.597. Average heterozygosity was 0.044 in P. c. compressa but 0.069 in P. c. improvisa, indicating a difference in genetic variability between the two subspecies. These results indicate that the two subspecies are genetically divergent. The number of divergent loci and genetic similarities pointed to useful in-dices for genetic divergence between closely related species in the process of speciation.

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Catadromous female eels were administered once a week with commercial gonadotropins, DES-Na and Vitamin E for a total of six occasions, and then with the acetone-dried pituitary glands of fishes several times over a suitably short period. The administration of LH-RH analogue was also tried at the later stage of maturation. Catadromous male eels were injected with the commercial gonadotropins and V.E on more than 5 occasions. The matured female and male eels were then kept in the same tank (1.6×3.5×0.9m, water depth 0.6m) and the above-mentioned hormone treatments were continued.
When they were kept at a water temperature of 18-20°C, spawning did not occur at all and even when fertilized eggs were obtained without any observable spawning behaviour the eggs did not hatch. But when the water temperature was raised to 21-22°C, spawning behaviour was observed at night and the spawning took place in the early morning. The fertilized eggs from this spawning hatched normally. The abdomen of the spawned eels swelled up once again over a considerably short duration in almost all cases, so it can be presumed that spawning can take place at least twice.
It is presumed that the normal body weight of female eels ranged between 110-130% (about 120%) of that at the start of the experiment, just before spawning. Mature female eels with a body weight of more than 130% always gave rise to denatured eggs.

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Amino acids function as feeding stimulants in many kinds of fish. In this study, we examined whether the feeding behavior in both male and female rose bitterling Rhodeus ocellatus ocellatus is induced by amino acids. Only the rose bitterling was attracted to a dialysis tube containing an amino acid solution, and it displayed a pecking behavior toward the tube. This pecking was not actually feeding behavior, because the fish did not open their mouths and their movement was very slow and gentle. But female fish did not show any pecking behavior. There is thus the possibility that this male-specific behavior may be sexual.
10 out of 20 amino acids induced male pecking behavior, the order of intensity being L-cysteine>L-serine>L-alanine>glycine>L-lysine, as determined by competitive assay.

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The sexual behavior of rose bitterling Rhodeus coellatus ocellatus was observed using a dialysis tube filled with an amino acid acid solution, and pecking behavior and sperm release were noted only in males. Pecking though similar to feeding was found to be sexual behavior. Both pecking behavior and sperm release were induced by the same amino acids, especially by L-cysteine, L-serine, L-alanine, glycine, and L-lysine. These two kinds of behavior changed alternately depending on light conditions. It is of interest that some amino acids which have no structural high spe-cificity induced sexual behavior similar to sexual pheromone.

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Growth rate effects on the relationship between otolith size and body size were examined in larval and juvenile goldfish. They were kept under the same environmental and feeding conditions, and sampled ad libitum until 154 days after hatching. Therefore, their variations in body size will be explained by internally mediated constraints on growth. After measurement of body size in standard length, three kinds of otolith were dissected under a binocular microscope and their morphological changes were noted.
The asteriscus was too small to be dissected consistently at hatching. The sagitta was considerably deformed with growth. The lapillus was relatively large at hatching and grew steadily from a round to a pear shape. For this reason, lapilli alone were used to measure otolith length (diameter or long axis) and to count the number of otolith increments.
Otoliths had three increments at hatching and subsequent increments deposited on a daily basis until at least 154 days after hatching. The relationship between otolith and body length showed an excellent correlation (r=0.92-0.97) within three groups which had different growth rates. However, analysis of covariance revealed a different slope of regression among the groups. This indicates that slow-growing fish have larger otoliths than equal-sized, rapidly growing fish.

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Matuda-Sannomiya's fish behavior model has been improved mainly on the basis of the experiment for rose bitterling Rhodeus ocellatus ocellatus. The model was reexamined for the behavior of Japanese dace Tribolodon hakonensis in a water tank experiment. The behavior of Japanese dace in a 1.7m equilateral octagonal water tank was recorded on video using 4 TV cameras which covered the whole area of the tank. On the basis of these time series data, the parameters included in the model were determined by the method of the least squares algo-rithm. However, some physical contradictions were observed in the parameters. This paper presents a modified model for describing the behavior of Japanese dace. In the new model, the interactive force between the fish and the attractive force of the wall were modified. The parameters in this model were suited, and the whiteness test of the residual was passed. The simulation by the modified model showed close agreement with the swimming behavior of Japanese dace.

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The catch efficiency of a 24.9cm BONGO net on anchovy larvae Engrauris japonicus was examined at three different towing speeds: low speed (about 0.8m/sec: L), middle speed (about 1.3m/sec: M), and high speed (about 1.8m/sec: H). The ratio of catch efficiency, which is equivalent to capture probability multiplied by mesh retention, was calculated at M speed to at H speed (E_M/E_H) and at L speed to at H speed (E_L/E_H) from the catch data of larvae.
In the daytime, E_L/E_H decreases as the size of the larvae increases, and this value was 0.94-1.09 over an interval of 2.5-3.5mm in S.L., and 0.67-0.87 over an interval of 4.5-9.5mm in S.L. Although E_M/E_H in the daytime decreases as the size of larvae over 7.5mm in S.L. increases, it is bigger than 1, 1.04-1.49, over an interval of 2.5-6.5mm in S.L. At night, E_L/E_H changes a little, 0.93-1.12, over an interval of 2.5-8.5mm in S.L. and decreases as the size of the larvae over 9.5mm increases in S.L. These results suggest that capture probability does not always increase as the towing speed increases, and that small larvae can not avoid plankton nets at night.

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This study deals with fluid dynamic drag on conical bag nets which were set in a flume tank at a constant speed. Five types of conical bag net of varying sizes were made from six kinds of Weaver's knot netting. These were constructed with eight sheets of isosceles triangular panels of polyamide netting.
Each of the conical bag nets was divided, according to its length, into four to eleven partitions (frustums of circular cone), in order to calculate the fluid dynamic drag. The angle of mesh opening and the angle of attack were determined from the meshes on frustum recorded on VTR by the computer graphics method.
The measured drags were compared with the calculated values from the equation derived from the experiments on the plane Weaver's knot netting.
The results obtained were as follows:
1) The calcultated values of fluid dynamic drag for the net type II, III, IV and V were similar with the measured ones.
2) In the case of the I type, the calculated drags did not agree with the measured drags; this was caused by interference with the legs.

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Tintinnids survive conditions unsuitable for growth by forming cysts which are deposited in bottom sediments. Various environmental factors may influence their excystment. In this study, the effects of temperature and light on tintinnid excystment from marine sediments were examined by incubating the sediment samples in filtered seawater at different temperatures. Tintinnid excystment was initiated on Day 1 at 15, 20, and 25°C or on Day 2 at 10°C. At the higher temperatures, the number of excystments rapidly reached the maximum and the cumu-lative number of excystments during the first 5 days was greater than at the lower temperatures. Dark conditions suppressed tintinnid excystment., Dependence of excystment on temperature was different for different species. The range of temperature suitable for excystment of each species coincided with the range of water temperature above the bottom during the period when the respective species was abundant in nature. These results imply that excystment plays an important role in increasing tintinnid populations in coastal waters.

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Standing crops of 9 species of macroalgae (Phaeophyta), 2 species of seagrasses, 4 species of sea urchins, and the spiny top shell was investigated at depths of 2, 5, 10, 15, and 20m along 23 transects on the coasts from west of Tappi to Fujishima, Tsugaru Peninsula, Aomori Prefecture on August 2-6, 1985. Characteristic differences were observed in their vertical distributions be-tween the Japan Sea coast and the Tsugaru Channel coast with Tappi Point as the border. The vertical distribution of standing crops of the spiny top shell and the sea urchin Strongylocentrotus nudus was quite similar to that of Ecklonia stolonifera and Laminaria japonica, respectively. These results suggest that the two species of seaweed, whether for food or habitat, are favored by sea animals.

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The present report describes the chemical and microbiological analyses of saba-narezushi (fermented mackerel with rice). The composition of narezushi (fish muscle portion) was as follows: pH 3.95, NaCl 1.37%, volatile basic nitrogen 16.8mg/100g, acetic acid 419mg/100g, propionic acid 103mg/100g, lactic acid 365mg/100g, inosinic acid 3.2mg/100g, and histamine 29.9mg/100g. Of free amino acids, alanine (175.5mg/100g) and leucine (124.0mg/100g) pre-dominated, followed by valine, isoleucine, phenylalanine, glycine, etc. Viable cell counts on GYP-, ABCM-, and BPG-medium were 2.4×10⁸/g, 2.0×10⁸/g, and 1.7×10⁷/g, respectively. The dominant microbial flora was Lactobacillus and Streptococcus followed by Bacillus, gram-negative rods, etc. Lactic acid bacteria isolated from saba-narezushi belonged to Lactobacillus plantarum, L. alimentarius, L. coryniformis (or related groups), Streptococcus lactis group, etc.

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A new heating apparatus equipped with electric current controllers that can be used for making kamaboko was produced as an experiment.
When salt-ground surimi prepared from walleye pollack, threadfin bream, white croaker, and sardine, and seasoned surimi from these were directly heated by conducting electricity through them with the apparatus, the rate of increase in their temperatures was 47°C/min, while the rate of heating with a thermo-bath was 0.9°C/min.
By this heating method (joule heating), the temperature of the surimi passed so rapidly through the “modori” temperature zone (about 60°C) that kamaboko with more firmness was produced.

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Salt-ground meat from walleye pollack frozen surimi was quickly heated by applying joule heat. The velocity of heating was controlled by changing the time (40s-40min) required for a uniform rise in temperature of the meat from 5°C to 90°C. The quality of the heated gel was assessed by measuring get strength together with cross-linking of myosin havey chains, and compared with that of kamaboko gel prepared by ordinary heating with a thermo-bath.
The gel strength of gel heated by joule heating became higher with a rise of heating velocity, and it was slightly superior to that of kamaboko gel. The cross-linking of myosin heavy chains (HC) did not occur during the heating of salt-ground meat by either method of heating. The contents of HC, actin, and other myofibrillar protein components were virtually unchanged among the heated gels formed by joule heating and by heating with a thermo-bath.
These results indicated that the heated gel formed by applying joule heat was very similar in its quality to kamaboko gel, although the gel strength of the former was slightly higher than that of the latter.

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Causes of undersirable browning which occur as a result of heatinm, g of shelled oysters stored at -35°Cand characteristics of brown pigments produced were investigated. Peroxide values (100-500 meq/kg lipids), which were measured by HPLC, of lipids in potential browning portions were more than ten times larger than those in normal portions, and nearly half of the polyunsaturated fatty acids of the former lipids had been oxidized during storage at -35°C for 6 to 16 months. Discoloration by steaming resulted in a decrease in peroxide value and polymerization of oxidized glycerides. Brown polymers obtained after steaming for 20 min were lipophilic but not hydrophilic. They were fluorescent substances composed of 2-5 molar oxidized glycerides, mainly triglycerides, having intact saturated fatty acids and oxidized polyunsaturated fatty acids, and of nitrogeneous compounds (1.0-1.5% N).

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The changes in contents of glycogen, glycolytic metabolites, ATP-related compounds, free amino acids, polyamines, and volatile basic nitrogen (VBN) were investigated in the leg muscle of tanner crab during storage at 5, 0, and -1°C in relation to freshness.
During storage, glycogen decomposed and lactate accumulated rapidly. Lactate reached its maximum level at the time when glycogen disappeared and later decreased at the stage of initial decomposition. As ATP decreased, inosine (HxR) together with IMP increased. The level of hypoxanthine (Hx) was low at the acceptable stage, but it increased rapidly at the stage of initial decomposition when both IMP and HxR degraded markedly. Ornithine (Orn) increased gradually during storage and formed noticeably as decomposition progressed. VBN also increased gradually during storage and reached a level of 24-28mg/100g at the stage of initial decomposition regardless of storage temperatures. Xanthine and cadaverine were absent at the acceptable stage and produced in small amounts at the stage of initial decomposition. From these results, H_x, Orn, and VBN seemed to be useful as potential indices for the fresh-ness of tanner crab.

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Seasonal variations of extractive components were examined in the muscle of disk abalone Haliotis discus collected from the coast of Amatsukominato, Chiba Prefecture at intervals of two or three months from July 1990 to July 1991.
The moisture content was highest in December after spawning season, thereafter decreased and became lowest in May. The total amount of ATP and its related compounds was highest in September. AMP was detected in high amounts from July to September. The level of glycogen was high in summer (over 6%), decreased remarkably in the spawning season and low in winter. Succinate was high in amounts from May to September. The total amount of free amino acids was highest in September and decreased to half in other months. The contents of glutamic acid, glycine, and AMP which are taste-active components were highest (470mg/100g) in September and lowest (130mg/100g) in February. Present study can demonstrate that disk abalones are palatable in summer, and watery and unpalatable in winter, which is generally told in Amatsu-kominato district.

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Sulfated derivatives of a polysaccharide prepared by chlorosulfonic acid treatment of a fucos-amine-containing polysaccharide from a marine Pseudomonas showed strong antiviral activity against herpes simplex type 1 (HSV-1). This sulfated polysaccharide inhibited the cytopathic effect of HSV-1 at 0.72μg/ml. No cytotoxic effects on Vero cells were detected with concent-rations of sulfated polysaccharide up to 1, 000μg/ml.

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The possible availability of deep seawater (DSW; seawater under the euphotic layer) and bac-teria isolated from DSW (BDS) for the mass culture of food microalga Chaetoceros ceratosporum was investigated. Seawater samples pumped up from a depth of 320m at the kochi Deep Seawater Laboratory in Muroto, Kochi Prefecture, were collected and used for cultivation of C. ceratos-porum. Growth rate (μ: reciprocal of the dubling time) and maximum cell yields (MCY) of the alga in untreated DSW were 1.25-2.22 (average 1.72).day^-1 and 2-11 (average 6) x 10⁵ cells/ml, respectively. When compared with those obtained by ASP₆ medium, the average, μin DSW was about 90% and the values of MCY were 5-20% of those in ASP₆. The values of MCY, however, showed a relatively large variance according to the sampling season of DSW. When some BDS were added to DSW, the growth of C. ceratosporum was often stimulated significantly; the μ values were 1.82-2.86 (average 2.27). day^-1 and MCYs were 4-12 (average 8) x 10⁵ cells/ml. Moreover, the variance of μ and MCY according to the sampling season tended to decrease when BDS were added. These results suggest that DSW has a high potential for cultivating food micro-algae, and it can be made more stable and effective by adding BDS.

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This study was conducted to investigate the effect of gelatinized ratio (GR) and digestible energy (DE) content on growth and blood profile of rainbow trout fingerlings (4.7g on aver-age). The fish were fed low energy (DE: 298-334kcal/100g) or high energy (DE: 334-395kcal/100g) diets with different levels of GR adjusted using raw and extruded potato starch at a 30% level.
At both dietary energy levels, growth, feed efficiency, and protein efficiency ratio were all improved by elevation of dietary GR levels, and reached a virtual plateau at around 40% GR. Daily feed consumption was inversely related to the dietary GR. At the same DE level (334kcal/100g) of both low and high energy diets, growth was higher in fish fed a diet with a higher GR.
The apparent digestibility of dietary protein was not influenced by dietary GR at either of the energy levels. Digestibility of lipid in the high energy diets and starch and energy in both energy levels increased with an increase of dietary GR. Blood profiles were also affected by both dietary GR and energy levels.
A suitable level of GR in the diet for rainbow trout was estimated to be more than 40%, regardless of DE levels.

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In order to investigate the effect of dietary gelatinized ratio (GR) and digestible energy (DE) content on the growth and blood profile of carp, fingerlings (8.5g on average) were fed low (DE: 253-393kcal/100g) or high (DE: 323-448kcal/100g) energy diets with different levels of GR adjusted using raw and extruded potato starch at a 40% level.
The growth was highest in fish fed on a low energy diet with 40% GR and a high energy diet with 20% GR. Daily feed consumption was inversely related to the dietary GR levels. Feed efficiency and protein efficiency ratio were improved by elevation of dietary GR at both energy levels.
The apparent digestibility of dietary lipid was not influenced by GR levels at low energy diets, but slightly by elevation of GR in high energy diets. On the other hand, the digestibility of starch and energy increased along with an increase a dietary GR levels in both the energy levels. Blood parameters were also affected by both dietary GR and energy levels.
A mixture of raw and gelatinized starch seemed to be suitable as a carbohydrate source in the diet for carp.

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The fatty acid composition of the edible ascidain Halocynthia roretzi was studied by means of open-tubular GLC with medium polarity phase Silar-5CP. About fifty components were ob-served, and their distribution among neutral and polar lipids was compared. The main fatty acids were found to be 14:0, 16:0, 16:1 (n-7), 18:0, 18:1 (n-9), 18:1 (n-7), 18:4 (n-3), 20:3 (n-3), 20:5 (n-3), and 22:6 (n-3). In monoenes, (n-7) series fatty acids were predominant, while nine tenths of the polyenoic fatty acids were represented by (n-3) series fatty acids, mainly eicosapen-taenoic. The literature data obtained by packed column GLC were compared with those obtained in the present investigation.

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Lipoxygenase-like activity was found in the crude extracts from the skin and gill of wild and cultured ayu. After incubation of arachidonic acid with the crude extract from the wild and cultured ayu skins, the major oxygenated product was estimated to be 12-hydroxyeicosa-tetraenoic acid under high-performance liquid chromatography using a Waters μ bondapak fatty acid column. On the other hand, eicosapentaenoic acid yielded 12-hydroxyeicosapentaenoic acid. This enzyme activity of wild and cultured ayu was inhibited strongly in the presence of the following reagents: BHA, esculetin, p-chloromercuribenzoate, SnCl₂, CuCl₂.
The C₉ carbonyl compounds and alcohols specifically formed from the oxidation of poly-unsaturated fatty acids in the crude extract of wild ayu skin. In GC-MS chromatogram, a peak height of (E, Z)-2, 6-nonadienal formed from the wild ayu skin was higher than that of the cultured ayu skin, while that of 3, 6-nonadien-l-ol from the wild ayu skin was lower than that from the cultured fish skin.

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A feeding trial was carried out to evaluate the nutritive value of soybean protein (SBP) for the juvenile freshwater prawn Macrobrachium rosenbergii (0.1g mean initial wet weight) compared with crab protein concentrate (CPC). Protein contents of the test diets ranged from 30 to 55% with an interval of about 7% and the dietary energy was kept constant (4.3 kcal/g) by adjusting carbohy-drate contents (α-starch and dextrin). Although the weight gain of CPC diet groups seemed to be higher than that of SBP diet groups at each protein level, no statistical significance was detected between SBP and CPC diet groups, with the exception of the prawns fed on the diet containing the second highest protein level (about 47%). There was a tendency for feed conversion efficiency (FCE) and protein efficiency ratio (PER) of SBP diet groups to be better than those of CPC diet groups in each protein level except for prawns fed on the second highest protein level (about 47%). The results above demonstrated that SBP could be a useful protein source for Macrobrachium diets. Protein levels tested in this study did not affect the growth, FCE, or PER in either CPC or SBP diet groups, which indicates the possibility of protein sparing by carbohydrate in M. rosenbergii. The proximate composition and amino acid pattern of the whole body were not affected by protein sources or levels.

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