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To validate the involvement of meiobenthos in cellulose breakdown in wetlands, meiobenthos were collected from sediments of Lake Furen and the Biwase River in Hokkaido Prefecture, the Kako River in Hyogo Prefecture, and the Chinai River in Shiga Prefecture. Cellulase activities of the meiobenthos were measured by cellulose zymographic analysis using sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) gels containing 0.5% carboxymethyl cellulose. The results showed that most of the Turbellaria, Nematoda, Harpacticoida, and Oligochaeta species exhibited cellulase activity. The molecular sizes of the cellulase-active bands of the sediments in Lake Furen, the Biwase River, and the Chinai River coincided with those of meiobenthos. The findings suggest that meiobenthos might play a major function in cellulose breakdown in these wetlands. This paper is the first to report cellulase activity in meiobenthos and that they are possibly involved in the breakdown of cellulose in wetlands. [ABSTRACT FROM AUTHOR]

The relationship between release date and migration speed was examined for hatchery chum salmon Oncorhynchus keta fry exiting the Nishibetsu River in eastern Hokkaido, northern Japan so that future releases might be scheduled so that fry arrive at the ocean during periods favoring high survival. Separate marked groups of chum salmon released in early April, mid-April, and early May in 2008, late March and mid-April in 2009, and mid-April in 2010 were recaptured with a rotary screw trap 12 km above the river mouth. Chum salmon in later release groups tended to migrate downstream faster than fish in earlier release groups. Those released after mid-April arrived in the lower river on average 9 days after release, while those released before mid-April arrived on average 26-28 days after release. Most marked fish arrived in the lower river during late April to mid-May. These results suggest that chum salmon are adapted to adjust their migratory speed so as to arrive at the ocean during a relatively discrete period, presumably during a time of high productivity favoring good survival. [ABSTRACT FROM AUTHOR]

The net-shape and loading analysis system (NaLA) was developed to determine fishing net configuration and load in a previous study. The system has since been applied to general gill nets and aquaculture nets, and its validity has been proven through model experiments in tanks. In this study, the system was applied to estimate the dynamic behavior of a bottom gill net for walleye pollock, to test the system's applicability of the system to gear operations in the field. To obtain in situ data, four bottom gill net operations were performed in February 2004 off the coast of Sawara, Hokkaido, Japan. During operations, vertical displacements of the bottom gill net's float and sinker lines were measured as representative values of gear behavior, and ocean current direction, and speed at the gear position were observed simultaneously. Then, bottom gill net behavior was simulated using NaLA, incorporating observed environmental conditions and gear specifications. The resulting calculated behavior was compared to measured behavior in terms of the relationship between net height and environmental or setting conditions. Agreement between the calculated and measured net behavior was found. Thus, it is believe that our NaLA calculation model has the potential to simulate the dynamic behavior of bottom gill nets in situ. [ABSTRACT FROM AUTHOR]

Age-based population assessment is widely used, but there are cases where information on age or even body length of landed fish is difficult to collect. In the present study, the biomass and fishing mortality of the southern Hokkaido stock of Pacific codGadus macrocephaluswas estimated directly from body weight composition, using weight-based virtual population analysis, from 1994 to 2000. The estimated biomass over 1 kg body weight was 5607 t in 1994 and increased to 7908 t in 2000. The increase was explained by an increase in recruitment. [ABSTRACT FROM AUTHOR]

Recreational fishing for masu salmon Oncorhynchus masou has recently become popular in coastal areas of south-western Hokkaido, including the Iburi district. We sampled recreational party boats in the Iburi district in the winters of 1998–1999 and 1999–2000. Daily numbers of anglers and catches of masu salmon were provided by the captains of the fishing boats. On average, anglers caught approximately four masu salmon per day each year, and peak catches occurred from late January to early February. Estimated numbers (standard errors in parentheses) of masu salmon caught by recreational anglers in the Iburi district were 66 844 (11 685) in 1998–1999 and 57 454 (6559) in 1999–2000, equivalent to 12–13% of the total annual commercial catches of masu salmon in Hokkaido. High recreational catches illustrate the importance of evaluating this fishery in the assessment and management of masu salmon in Hokkaido. [ABSTRACT FROM AUTHOR]

SUMMARY:The ages of individual specimens of white-spotted char Salvelinus leucomaenis, collected from the Furuu River in Hokkaido, Japan, were determined from otoliths using NIH Image. We employed two methods to determine age. First, for a surface method (traditional method), the ages were made from examinations of otoliths under a microscope by experienced readers A, B and an unexperienced reader C. Second, for an auto-counting method, a computer program was used to detect the peaks from otolith images. We made a mathematical model to estimate the probability of a correct reading for each reader, using the results of the age determination and the per cent age agreement among readers. The ability to determine the age of white-spotted char depended on whether or not the reader had ever previously made age determinations. The ability of auto-counting method was below that of reader A (one of the experts), and the method was slightly superior to reader B (the other expert). [ABSTRACT FROM AUTHOR]

SUMMARY:Eighteen samples of virus-like growth suppression agents against the marine phytoplankton Alexandrium catenella, Gymnodinium mikimotoi and Tetraselmis sp., obtained from the coastal waters at the mouth of Funka Bay, Hokkaido, Japan, from 1993 to 1995, were characterized on size estimation, heat stability, nuclease sensitivity, proteinase K sensitivity, stability under acidic condition, titration, diethyl ether sensitivity, and ultraviolet (UV) sensitivity. All agents were affected by heating at 50°C for 30 min, exposure to acidic conditions below pH 5.0, passing through a 0.05 μm filter, RNase treatment, and irradiation of UV dosage at 5 × 104 μW/s per cm2. The growth suppression effects of 11 agents from Tetraselmis sp. and A. catenella disappeared after proteinase K treatment, however, seven agents from G. mikimotoi were unaffected by this treatment. Furthermore, 11 agents against Tetraselmis sp. and A. catenella were collected from the bottom fraction by ultracentrifugation, while seven agents against G. mikimotoi were collected from the upper fraction, not from the precipitated fraction. These results suggest that at least two types exist in the virus-like agents showing growth suppression for phytoplankton. [ABSTRACT FROM AUTHOR]

The article reports on a study of the impact of low temperature on the mating behavior of squid Loligo bleekeri in Hokkaido, Japan. It caught squids in an inshore set net at Matsumae in April 2002 and was brought to the Usujiri Fisheries Station, Field Science Center for Northern Biosphere. It used an experimental tank with a water-circulation system and to cooler-heater units. It founds out that squids mating positions were either head-to-head or male-parallel. It also showed that female squids that mate in head-to-head position store sperm in their seminal receptacle while male-parallel position was made by male squids before spawning.

The article discusses the scallop Patinopecten yessoensis. Accordingly, as one of the major marine products in Hokkaido, Japan, 200,000 estimated tons per year of scallop shells are generated as industrial waste. Scallop shells have been used as a source of calcium and material for desulfurization. This process involves adhere materials to be brushed, then crushed to powder. After which, the powdered shells were dialized in contact of one liter of 5% acetic acid, and be decalcified. Furthermore, several graphs are shown on the increase of messenger RNA (mRNA) expression of uncoupling protein 1 in differentiated C3H10T1/2 adipocyte cells in scallop shell extract.

The article presents the promotion of lypolysis activity in mouse adipocyte cells by scallop shells extracts. A huge number of scallop shells in Hokkaido, Japan are just industrial wastes. The extracts of the scallop shells can be used as a cosmetic. It has the ability to promote lipolysis activity in adipocyte shells that can be used in cosmetics. It has the potential to be an antiobesity drug or food for obese people. In the article, a study is conducted to show the use of the extracts for cosmetics.

Reports on the catch of harbor porpoise Phococena phococena in the coastal waters of Southern Hokkaido, Japan. Factors responsible for the depletion of porpoise population; Observations made on porpoises; Areas of concentration of population of harbor porpoises during summer season.

Presents the abundance and energy content of mysid Neomysis czerniawskii in Hokkaido, Japan. Optimum releasing time of juvenile Japanese flounder; Relation of seasonal variations in energy content of invertebrates to the reproductive cycle; Body sizes of predator and prey.

Discusses a study which proposed a defined morphological developmental phase in the early life history of the Japanese smelt fish, Hypomesus nipponensis, found in Lake Abashiri in Hokkaido, Japan. Methodology of the study; Results and discussion.