This paper proposes a method for estimating the mortality rate and divers' sighting rate by taking the effect of movement of abalones into consideration, from the data of the number of alive and dead abalones counted by divers at survey day and the initial number of tagged abalones. The abalones are classified into four states by the combination from the elements as alive or dead and observable or unobservale. The probabilities for the states at survey day t are presented by a stationary Markov chain. The probabilities which an abalone is sighted alive or dead at t are given by the products of the probabilities of the divers' sighting and the probabilities for the alive or dead states in the observable. The log-likelihood function L is obtained from the multinominal distribution. The unknown parameters are estimated. by maximizing L. The variance-covariance matrix of the estimates is approximately given by the inverse of the information matrix. The values of the parameters for maximizing L are found by Davidon's variable metric method. Furthermore, the method is applied to the data of Japanese black abalone Haliotis discus discus in the coast off Chiba Prefecture. The estimates of the mortality rate per day are about 3.2% for group 1 (10-24mm) and 0.64% for group 2 (22-30mm). The true values of the sighting rate for alive abalones are 41% at one day after releare, 23% at six, 20% at fourty five for group 1, and 37%, 15% and 13% for group 2, respectively. The limitations of the application and the modification of the method are discussed.

View full abstract

A new, opening-closing, paired zooplankton sampler for horizontal or oblique towing was built and tested. Two nets, which have cylinder-cone filtering section and canvas collar, are at-tached to a frame constructed with two acrylic pipes (23.4cm I. D.). The nets are opened and closed by means of a double releaser (General Oceanics). The sampler is simple to consturct and easy to use, and furthermore it is very light (6.5kg in air).
In 151 tows, the sampler fuctioned 97 percent of the time. A depth of the sampler changes scarcely even when the nets are opened. The revolution number of a flowmeter attached in the pipe is little during the nets closing. Consequently the revolution number of a flowmeter can give the correct filtered water volume.

View full abstract

Large-scale wake is generated behind a bluff body being widely used elements of submerged structure.
Until now, added mass component of unsteady force acting on the body was generally calcu-lated by potential theory. However, the real flow that has the wake behind a body is different from the potential flow.
Unsteady force is calculated more accurately by using a new dimensionless number, we de-signate as “wake mass coefficient” which can be calculated by the change of the wake momentum.
Judging from the experimental result of a normal plate, wake mass coefficient comes to the values of 0.17 by way of a universal constant independent of Reynolds number and accerelation of principal flow.
It suggests that the generation of added mass is largely related to the growth of the wake behind a body.

View full abstract

To investigate the combined effects of temperature and photoperiod on molting (reproductive molt, R; common molt, C), reproduction and growth of Macrobrachium rosenbergii, six groups of 14 females each were exposed to 12L12D or 15L9D, at 24, 28 or 32°C for a period of 140 days. Survival rates were satisfactory with the exception of treatment under 24°C/15L9D which caused high mortality. R frequency tended to increase with the elevation of the water temperature. Ex-posure to 32°C/12L12D significantly enhanced R frequency. Duration of molt intervals decreased with increased temperature. Both C-R and R-R intervals were longer than C-C intervals. Growth was faster at 28 and 32°C than at 24°C, and was enhanced under 12L12D. The highest condition factor was obtained under 28°C/12L12D. Increased temperature under 15L91D decreased growth rate after the occurrence of C-C. Under 12L12D growth rate decreased after the occurrence of C-R or R-R. Under any treatment, growth rate after R was lower than after C. Antagonistic interactions between reproduction and molting, and between reproduction and growth are evidenced and discussed.

View full abstract

The foam separating system was examined in terms of the removability of pollutants from fish-rearing seawater in living fish transportation and preservation. The foam-separating system consisted of fish-rearing tank (seawater volume of 890 l; sea bream Pagrus major weight of 50kg), a circulation pump, an air-inhale-discharge-type aerator unit, a foam-separating unit and a filtering unit. The fish-rearing seawater and separated foam wastewater were analyzed every 3-6h for two days.
The pH, DO, turbidity, NO₃-N, NO₂-N, total viable bacteria, and vibrios in fish-rearing seawater were maintained for two days at 7.5-7.9, 7.2-7.4mg/l(17°C), 1-2 TU, ND-0.005mg/l, 0.01-0.08mg/l, <10⁵ CFU/ml, and 20-30CFU/ml, respectively. The concentrations of dissolved organic carbon (DOC) and NH₄-N were 21.5mg/l and 9.0mg/l after fish rearing for two days. Turbidity, DOC, total viable bacteria, and vibrios were removed effectively by foam-separating system. The volume of foam wastewater removed during the two-day period was only 1.2% of the initial volume of fish-rearing seawater. The foam-separating system was very effective in removing pollutants from the fish-rearing seawater.

View full abstract

Methodologies to utilize fishing information have only a few results, though the development of them are emphatically needed. Hence, authors considered modeling of the productivity index of a fishing ground M to be available for detection of f.c. (fishing conditions) or selection of fishing ground.
Using data of radio information on tuna longline f.c. among ships, M was constructed as equations (1), (2) and (3), where l₁ and l₂: coefficients, μ, σ: mean and standard deviation of total catch in fishing ground; H: information reliability index; p: fales information probability; N: number of ships. H was adopted in the model for the purpose of correcting the probable false information in f.c. by radio. 1/σ signifies the stability of f.c. and was introduced into the model. μ can be an index of f.c. but changes in a manner of second degree curve. Hence, μ² as well as μ must be variables in the model.
Thus the model was constructed theoretically. The practicable equation (6) was obtained through the determination of coefficients by multivariates analysis, wherein R (the mean of catch by selected training ships) was used as objective variable instead of M.
The results were shown really and satisfactorily in Fig. 4, which verifies the effectiveness of the model.

View full abstract

Effects of stress and fasting on plasma growth hormone (GH) levels were examined in the rainbow trout. Handling stress in shallow water for 30 min caused an immediate hyperglycemia which lasted for 6h, whereas a singificant increase in plasma GH levels was observed 6 and 12h after the stress. Plasma GH levels increased by starvation of 28 days, where significant hypoglycemia was observed. Intraperitoneal injection of bovine insulin (4 IU/100g body wt.) caused a significant increase in the plasma GH level 30 min after injection, although there was no change in the plasma glucose levels. Plasma GH levels also increased 30 min after saline injection. Thus, no significant difference was seen in the plasma profiles of GH between the saline-and insulin-injected fish, suggesting that the trout responded to “injection stress” by increased plasma GH. On the other hand, injection of glucose (100mg/100g body wt.) significantly increased plasma glucose levels over 6h, whereas there was no change in plasma GH levels. These results suggest that plasma GH levels of the trout are susceptible to stress and starvation, and that high plasma glucose evels may have an inhibitory effect on stress-induced GH secretion.

View full abstract

The activity of leucocytes isolated from the anetrior kidney of rainbow trout Oncorhynchus mykiss vaccinated with formalinkilled Vibrio anguillarum, β-haemolytic Streptococcus sp. or Renibacterium salmoninarum were investigated using the chemiluminesecnce (CL) assay. The vibrio and streptococcal bacterins were administrated by intraperitoneal injection or by the direct immersion method. The R. salmoninarum bacterin was inoculated intraperitoneally. The CL response of leucocytes from fish injected with vibrio or streptococcal bacterin was excellent against each opsonized bacterial cell. The leucocytes of each fish administrated by the immersion method also showed a high response level; however these emitted light levels were less than those of fish vaccinated by injection. The enhancement of CL response was not observed on the leucocytes of fish vacclnated with R. salmoninarum bacterin.

View full abstract

The relationship between width of line target and distance at the limit of discrimination was examined by means of the conditioned reflex method. Japanese parrotfish Oplegnathus fasciatus as experimental fish and distances from 50cm to 200cm were used. Target board was made of white acrylic resin with a vertical black line in the center. The width of line target was changed from 0.2 to 8.0mm.
The width of line target at the limit of discrimination increased exponentially with an increase in the distance. The width of line target φ (mm) at the limit of discrimination was shown to be an exponential function of the distance L (cm) as follow, φ=exp (1.768 10^-2 L-2.287)

View full abstract

A potassium thiocyanate extract (PTE) from a virulent isolate of Pasteurella piscicida was prepared as antigens, and acetic acid-treated, naked bacteria (NB) reported as immune carriers were prepared from the same isolate. Yellowtail Seriola quinqueradiata were vaccinated intraperitone-ally twice, at one week interval, with PTE, or mixture of PTE and NB, and were challenged by artificial water borne infection two weeks after the last immunization. PTE alone provided only partial protection. However, a mixture of PTE and NB protected the challenged fish significantly (relative percent survival: 36%), and NB was found to have co-operating protective effect with PTE. Regarding PTE-specific antibody levels in the sera and the skin mucus from immunized groups, a mixture of PTE and NB induced lower levels of the antibodies than PTE alone. More-over, bactericidal activities were not observed in the sera from the fish of any vaccinated groups. These results suggest that humoral immunity does not play an important role in this protection.

View full abstract

The rose bitterling Rhodeus ocellatus ocellatus, Cyprinidae, a spring and summer breeder, were captured in out of the breeding season (early November). They were divided into three temperature groups (5, 10, and 15°C), and reared under a short photoperiod (1OL-14D) for 60 days. Then each group was divided into two photoperiod groups; a long (14L-10D) and the short (continued) photo-period group, and all the groups were kept at 15°C for another 37 days. In females gonadal re-crudescence did not occur in any temperature group during first 60 days. However at the end of the experiment (late February), gonadosomatic indices (GSIs) of ovaries had significantly increased in all the long photoperiod groups. On the other hand, only the females pre-treated by warmer temperatures (10 and 15°C) for 60 days showed some gonadal recrudescence under the short photo-period. Male bitterling represented almost the same pattern of the change of GSIs during the experiment, but some individuals had attained the spermiogenesis in all the groups at the end of the experiment. These results indicate that in the post spawning season, the photoperiodism in-volved in maturation of the rose bitterling declines under natural temperatures of late autumn (10-15°C). Low temperatures of winter do not seem to be essential for the gonadal maturation in spring during the annual reproductive cycles of this species.

View full abstract

A new bioassay procedure using Avicel plates has been established to screen algal feeding inhibitors for marine herbivorous gastropods, the abalone Haliotis discus, the turban shell Turbo cornutus and the top shell Omphalius pfeifferi and the sea urchin Strongylocentrotus intermedius, Application of this assay procedure to an Australian red alga Phacelocarpus labillardieri resulted in isolation of a macrocyclic γ-pyrone as a very potent feeding inhibitor for the marine herbivores mentioned above.

View full abstract

An enzyme immunoassay (EIA), based on a competitive assay system, for the measurement of growth hormone (GH) in the pituitary of salmonid fishes and for the hormone released into pituitary incubation medium was developed usíng a rabbit antiserum against natural chum salmon growth hormone (nsGH I) isolated from pituitary glands. Recombinant salmon GH (rsGH I), was coupled to horseradish peroxidase (HRP). Antibody-bound HRP-rsGH I was separated from free HRP-rsGH I by a double antibody precipitation method. The enzyme activity in the precipitate was detected by a colorimetric method, in which o-phenylenediamine and hydrogen peroxide were used as substrates. nsGH I and rsGH I showed different affinity to the antibody. The displacement curves for extracts from chum salmon and rainbow trout pituitaríes, and incubation medium of the pars distalis of the trout were parallel to the GH standard, indicating that the present GH-EIA could estimate GH concentrations in those solutions. An alkaline solution was more effective than saline to extract GH from the pituitary gland. Among the chum salmon adenohy-phophyseal hormones examined, only gonadotropin I showed slight cross-reactivity (less than 0.1%). Neurohypophyseal hormones such as arginine vasotocin and isotocin showed slight (1%) and parallel cross-reactivities to the standard hormone.

View full abstract

Relationship between hematocrit value and arterial blood gases were examined on the carp which had various levels of hematocrit value (4.8-25.9%) and hemoglobin concentration (1.30-8.60g/dl) by taking out various amount of arterial blood. With decrease of hematocrit value, oxygen content of the blood and protein concentration of the plasma decreased straightly, and total carbon dioxide content of the blood increased. Although hematocrit value decreased, oxygen consumption, pH and oxygen pressure of the blood were not affected by the decrease and showed the constant levels.

View full abstract

The carotenoids in the muscle of the sea hare Dolabella auricularia were investigated. An apocarotenoid has been isolated and its structure was elucidated to be β-apo-8'-carotenal on the basis of the spectral data. β-Apo-8'-carotenol which seems to be a metabolic carotenoid of β-apo-8'-carotenal was also isolated. Besides these two carotenoids, 9-cis-β-apo-8'-carotenal, citranaxanthin, lutein and fucoxanthin were identified.

View full abstract

Viable cell count sensors were composed of immobilized bacteria such as A. putrefaciens, E. coli, P. fluorescens, S. aureus and mixture of bacteria, and oxygen electrode. The sensors were used at pH 7.2 and 25°C. Good relationships were obtained between the output of each sensor and the viable cell count. Viable cell counts in bluefin tuna and mackerel muscles were also measured by the proposed sensor. From the results obtained, it was recognized that the proposed biosensor was applicable to the rapid and simple determination of viable cell count in fish meat with accuracy of six hundred orders or eight hundred orders. One assay could be completed within 20 min.

View full abstract

Yellowtails Seriola quingueradiata were fed on non-treated, 40°C-heated, and extruder-pro-cessed brown fish meals supplemented with vitamin and mineral mixtures and pollack liver oil for 30 days. Dietary α-tocopherol was also kept constant at a level of about 90mg per 100g. Their tissue 2-thiobarbituric acid (TBA) values and superoxide dismutase and glutathione peroxidase activities as well as the resistance of yellowtails to Streptococcus sp. were examined.
Between the experimental groups of fish, no differnces were observed in the growth, the tissue enzyme activities and the resistance to Streptococcus sp.; the latter results showed that fish infected with Streptococcus sp. had strong resistance with their survival rate being high regardless of the diets used. High α-tocopherol contents and low TBA values of the diets used in the present study probably resulted in the low tissue TBA values for all the fish groups. These results also suggest that the resulting protection of various tissues of yellowtails against lipid peroxidation may be as-sociated with the possible enhancement of their biological protective ability.

View full abstract

Two feeding experiments were conducted to determine the suitable dietary protein and lipid levels for fingerlings of red sea bream by feeding them with various white fish meal-casein diets containing different levels of protein (CP: 37-52%) and lipid (CL: 5-20%).
In Experiment I, the growth rate and feed efficiency increased with increasing CP content in diet, both values reaching a maximum at the diet level of 52%. In Experiment II, the growth rate and feed efficiency were higher for diets containing 52% CP, compared to 42% CP groups, irrespective of the lipid levels. On the other hand, with an increase in the amount of dietary n-3HUFA, the values for growth rate, feed efficiency, and protein efficiency ratio increased, recording high in diets combining 52% CP with 15 and 20% lipids.
This result indicated that the growth of red sea bream fingerlings was influenced by not only di-etary protein and lipid levels but also n-3HUFA contents in diet. It is also suggested that the suitable CP and CL levels in diet for red sea bream fingerlings may be around 52% and 15%, respectively.

View full abstract

Nori Porphyra spp. is one of the most important seavegetables (edible seaweeds) in Japan. Texture, especially the softness as well as a color and gloss, has recently become to be an important factor for the quality of sheet-like dried nori called hoshi nori. The purpose of this study is to build up a profile of favorable texture of hoshi nori.
The elongation and rupture strength of six samples were measured by a tensipressor. Sensory evaluation was practiced by five professional technicians. They recoreded the rank of softness employing a line scale method.
For the dried samples, the order of elongation and rupture strength agreed essentially with the rank of softness by sensory evaluation. However, the degree of the strength was different from the results of the sensory evaluation. For the wetted samples, the order of the rupture strength did not agree with that for the dried ones, but with the order of the time required to peel into nori pieces in water. The result of the sensory evaluation showed a tendency to separate into only two textural categories, i.e. soft and firm. A similar tendency was observed for the peeling time. These results suggested that there are two sensory systems in our mouth; one was a system perceived nori as soft on the basis of the force to slide each piece of nori, and another was a system that perceived nori as firm on the basis of the force to bite it off.

View full abstract

A mating inhibitor which inhibits sexual agglutination and gametic fusion of Chlamydomonas reinhardtii and hypnozygote formation of Alexandrium catenella was detected from bacterium strain NT4. The inhibitor (MI) has been successfully purified from a culture supernatant by a combination of Amberlite IRC-50, CM-cellulose 52, and high preformance liquid chromatographies. MI was separated into four derivatives (MI-1, MI-2, MI-3, MI-4), of which MI-1 was identified by spectral analyses (HR-MS, NMR) and chemical degradations to be 3-(4-hydroxyphenyl)-β-alanyl-2-hydroxy-β-alanyl-3-aminoalanyl-ζ-hydroxy-α, ε-diamino-η-azelayl-N-(3-((4-aminobutyl)amino) propyl)glycinamide. This is identical with antibiotic edeine Al, a known inhibitor of DNA synthesis. Bacterial strain NT4 producing the inhibitor was identified as Bacillus brevis.

View full abstract

Highly purified tetrodotoxin (TTX) was fed with diet to a marine snail Neptunea arthritica which has been consumed as a food without TTX poinsoning. No specimens died from the toxic diet, showing that they are resistant to TTX. About 40%. of the supplied TTX was detected in the digestive gland at 3 days after the last supply of the diet. On the contrary, no toxin was detected in the muscle. TTX accumulated in the digestive gland decreased to less than one third when they were reared for 30 days without feeding.

View full abstract

The denaturation of carp myosin B (in the presence of 0.6_M KCl) during the slow freezing process where a gradual increase in salt concentration occurs by freezing point depression, was investigated in comparison with that of the quick freezing sample. Changes in Ca-and Mg-ATPase activities showed that the binding ability between myosin and actin was weakened by the exposure to the concentrated salt solution. When the samples were rapidly frozen to -20°C at an appro-priate point during the slow freezing process and then stored at -20°C, the apparent rate con-stants for the freeze denaturation were equalled, regardless of the freezing process. The apparent rate constant for the thermal inactivation of myosin B sampled at the appropriate point on the slow freezing curve showed a two-phased first-order inactivation mode after the first moment of arrival at the eutectic point. And the single-phased first-order inactivation mode was restored by the addition of carp F-actin to its myosin B. This phenomenon shows that a portion of F-actin in myosin B was denatured as a result of the exposure to the concentrated salt solution. However, the two-phased mode of thermal inactivation was not observed in the quick freezing sample.

View full abstract

Oligosaccharidase activity of a neutral β-N-acetylglucosaminidase from carp blood was examined. The enzyme hydrolyzed the trisaccharides (GlcNAcβ1-4GlcNAcβ1-4GlcNAc and GlcNAcβ1-4GlcUAβ1-3GlcNAc) derived from chitin and hyaluronic acid, but did not hydrolyze the trisaccharide (GalNAcβ1-4GlcUAβ1-3GalNAc) derived from chondroitin. The C-4 configuration of thenon-reducing terminal N-acetylhexosamine in substrates is an important determinant of the specificity of the enzyme, while the subterminal sugar and position of β-linkage are not strictly required by the enzyme.

View full abstract

The amounts of ATP related compounds during storage and some properties of IMP degrading enzyme in the ordinary muscle of the golden snapper Pagrus auratus from waters around New Zealand were examined.
When the muscle were stored for five days at 4°C, IMP remarkably decreased and hypoxanthine increased, whereas the amount of inosine was low and scarcely changed during storage. The amounts of IMP in the muscle hardly changed during storage for 43days at-20°C.
IMP was degraded optimally at pH6.2 and pH8.4 in dorsal muscle homogenate of golden snapper. The IMP-degrading activity in the minced dorsal muscle decreased by the storage for one day at 4°C, showing 82.5% of initial activity, and since then, the activity decreased rapidly, showing 17.5% after seven days of storage.
The IMP-degrading activity of crude enzyme extracted from the golden snapper muscle using the detergent remarkably increased at pH8.0 in the presence of 2m_M Mg²⁺ and stabilized at pH7.0 for 48h (2±1°C).

View full abstract

The thermal measurements using a differential scanning calorimeter was done with 10 kinds of fish meat, cuttlefish meat paste, and chicken meat paste. The total enthalpy change, ΔH, accompanied with the thermal gelation of meat pastes were estimated. Consequently, it was found that the easy-setting meat and the easy-disintegrating meat required a small quantity of heat in order to change the structure. The setting index (S) and the disintegration index (D) reported by Shimizu et al. depends on the ΔH-values as follows; ΔH=-0.0074S+1.047 ΔH=-0.0038D+0.783. Namely, the easy-setting property or the easy-disintegrating property corresponds to the fact that these meat pastes easily changed by a small quantity of heat. On the other hand, the correlation could not be found between ΔH and the gel-strength reported by Shimizu et al.

View full abstract

Mode of action of the crown-of-thorns starfish Acanthaster planci lethal factor was examined by intravenous injection into rats. Autopsy of the rats revealed that the lethal factor induced a change in color of the liver, swelling of the gall bladder and jaundice. Both body and liver weights were decreased with time, activities of glutamic oxaloacetic transaminase and glutamic pyruvic transaminase in serum were significantly elevated, and hepatic lipid contents were increased. Free fatty acids were increased in both liver and serum, suggesting the enhancement of lipolysis. Total cholesterol was also increased in both liver and serum and triglycerides only in the liver, while phosoholipids were neither increased nor decreased in both liver and serum. These results evidenced that the A. planci lethal factor is a potent hepatotoxin disturbing the lipid metabolism.

View full abstract