The target strength (TS) of juvenile sandeel (3.1-7.7 cm in standard length, SL) was measured for various tilt angles (−30° to 30°) at 120 kHz, and was compared with the theoretical TS calculated using the theoretical sound scattering model. The maximum TS measured at the tilt angle of 0° ranged from −68.8 to −60.8 dB, whereas the range of the theoretical TS was from −68.7 to −61.5 dB. The difference of the measured and theoretical values of the maximum TS was −1.6 to 0.9 dB, and the TS patterns showed good agreement, particularly in the range of the main lobes, in the tilt angle (−10° to 10°). The theoretical model was used to calculate the TS under the same conditions where the specimens were collected. The correlation between the SL and the maximum TS is given by the equation: TS=43.1 log SL−96.1.

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  We report measurements of the C and N stable isotope ratios (δ¹³C and δ¹⁵N) in tissue of the bivalve Corbicula japonica and particulate organic matter (POM), and the C/N ratios of microalgae, terrestrial plants and sedimentary organic matter in Natori River, Miyagi Prefecture, Japan. δ¹³C of the bivalve and POM at upstream stations (4.0∼4.5 km from the river mouth) were significantly lower than those in the downstream station (1.5 km from the river mouth). The low δ¹³C values in the upper two stations (between −28.0 and −25.5‰) indicated that terrestrial organic matter is the primary C source of the bivalve. However, δ¹⁵N values for the bivalve at all stations (between 9.5 and 10.8‰) did not differ significantly. This suggests that benthic microalgae are the primary N source in all stations. We conclude that C and N sources for the bivalve originate from different food items in the upper reaches of the river.

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  Until recently, it was thought that Japanese populations of chum salmon Oncorhynchus keta consisted entirely of hatchery fish. However, the presence of a significant proportion of wild fish has now been documented in some populations. To allow for differential management of both wild and hatchery salmon, it is important to understand the differences and similarities that exist in a number of measurable biological traits. We compared age and body size at maturity of wild and hatchery fish collected from three rivers in which the otoliths of all hatchery-origin fry were thermally marked. The difference between wild and hatchery fish varied among rivers. In one river, wild fish were older and larger than hatchery fish. In the second river, there was no difference between hatchery and wild fish, whereas in the third river, the age-related increase in body size of wild fish was smaller than that of hatchery fish.

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  To clarify the growth of female beni-zuwai crab Chionoecetes japonicus, they were collected from the central part of Toyama Bay at the depth of 1060-1270 m by beam trawls from 2006 to 2011. Carapace width (CW) measurements revealed 9 and 2 modes in the size frequency distribution in juvenile and immature, and adult female, crabs respectively. Dividing into each normal distribution by the Hasselblad method, the mean size in CW was estimated to be 6.3, 9.0, 12.8, 18.0, 24.4, 33.2, 43.2, 56.1 and 66.1 mm in juvenile and immature crabs, and 68.5 and 81.5 mm in adult crabs, which were thought to mean CW at the 3rd to 11th instars and 11th to 12th instars, respectively. The size frequency distribution showed that most females would experience terminal molt at the 10th instar and grow into adult females at the 11th instar.

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  The effects of lowered temperature on lipid content, fatty acid content and fatty acids composition in fertilized eggs and phyllosoma of spiny lobster Panulirus japonicus were investigated. During egg development, the consumption of lipids in eggs was estimated to be 84% (22℃) and 85% (15℃). Fatty acids consumption was 66% at 22℃ and 88% at 15℃, and DHA consumption was 43% at 22℃ and 81% at 15℃. Larval hatching was completed within 36 to 40 days at 22℃ and 50 to 54 days at 15℃, indicating that the daily consumption of lipids in individual eggs was 233 ng•d⁻¹ at 22℃ and 196 ng•d⁻¹ at 15℃. Daily fatty acids consumption in individual eggs was 65.2 ng•d⁻¹ at 22℃ and 58.8 ng•d⁻¹ at 15℃. Daily consumption of DHA in individual eggs was 2.10 ng•d⁻¹ at 22℃ and 3.25 ng•d⁻¹ at 15℃. We conclude that lower temperature promotes DHA consumption during egg development of the lobster.

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  Sea horse Hippocampus kelloggi is used as a traditional medicine in Asia for a tonic. In this study, we prepared a 35% ethanol extract of sea horse (SHEtEx.35), and then demonstrated the effects of SHEtEx.35 on antigen (Ag)-stimulated degranulation in rat basophilic leukemia RBL-2H3 cells. The inhibition level of Ag-stimulated degranulation by SHEtEx.35 gradually increased to 25 μg/mL, but the inhibition levels of Ag-stimulated degranulation by SHEtEx.35 did not change at concentrations above 25 μg/mL. In order to elucidate the underlying mechanisms, we examined the effects of SHEtEx.35 on early intracellular signaling events (intracellular free Ca²⁺ ([Ca²⁺]i) concentration, and intracellular reactive oxygen species (ROS) production) by antigen stimulation. Treatment with SHEtEx.35 markedly suppressed antigen-stimulated activation of PLCγ1 and elevation of [Ca²⁺]i. However, SHEtEx.35 did not suppress antigen-stimulated ROS production. These results indicate that inhibition of antigen-stimulated degranulation by SHEtEx.35 is mainly due to direct inhibition of PLCγ1 activation. Our findings suggest that SHEtEx.35 would be beneficial for alleviating symptoms of type I allergies.

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  The effect of NaCl and organic salts (Na-citrate, Na-acetate, Na-benzoate and Na-tartrate) on the properties of surimi-based films prepared from Alaska pollack frozen surimi was investigated. The solubility of the surimi protein increased upon addition of the salts. Na-citrate and NaCl appeared to have the highest ability to dissolve the protein among the salts. The surimi were dissolved into salt solutions at neutral pH and dried (25±0.5℃ and 50±2% RH) to form the film. Physical properties and SDS-PAGE of the resultant films were determined. The films with Na-tartrate and NaCl were crystallized during the drying process. By adding the salts, tensile strength (TS), elongation at break (EAB), and water vapor permeability (WVP) of the film were increased while transparency of the film was decreased (became transparent) compared to those of the control (no salts added). SDS-PAGE indicated that the protein patterns of the film were not significantly different among the salt types used as a solubilizer. Na-citrate showed the highest effects on increasing TS and decreasing transparency of the film among the salts used in the study.

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  Essential parameters for the system design and optimum operation control of our system for removing cadmium from squid viscera by means of the competitive adsorption method were determined. The overall heat transfer coefficient of the squid viscera dissolution (auto-degradation) process was determined by Newton's heat transfer equation using the data obtained from laboratory-scale experiments. The temperature rising behavior of squid viscera closely followed Newton's equation. The results calculated from Newton's equation with the determined overall heat transfer coefficient matched the temperature rising behavior of squid viscera in a 1000-fold larger pilot scale squid viscera dissolution tank. The filter medium resistance and the specific cake resistance of solid matter in dissolved squid viscera were determined by Ruth's filtration equation. The filtration behavior of dissolved squid viscera closely followed Ruth's equation, and the filter medium resistance and the specific cake resistance could be obtained.

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  Household consumption of marine products in Japan is decreasing, but the reasons are not clear. Although the change might be related to the changing preference from Japanese food to European food, there is no quantitative evidence. This study examined the changes in market situation in Japan, and conducted a demand system analysis of Japanese household consumption of animal protein. The results showed that the decreasing consumption of marine products is caused by declining household income, and that the shift in consumption from marine products to pork and chicken is because those proteins are cheaper than marine products or beef.

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[in Japanese]

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