In 1996, the Japanese government enacted “The law for the preservation and management of marine fisheries resources” and introduced a Total Allowable Catch （TAC） management system for walleye pollock, Japanese common squid, Pacific saury, and other species. This will require more accurate estimates of stock abundance and better management methods. Acoustic techniques using scientific echosounders are one way to estimate the distribution and abundance of fish. Such techniques are commonly used, especially in Northern Europe and North America, because they can survey large areas of ocean relatively quickly. However, before such surveys can be conducted, the acoustic characteristics of the target species must be known. In Japan, acoustic techniques are not often used because there are many species in the waters around Japan. Many studies have examined the acoustic characteristics of commercial aquatic organisms. However, it is difficult to estimate their abundance using only the acoustic characteristics of those organisms because many non-commercial aquatic organisms also live in the sea. Therefore, in this study, I determine the acoustic characteristics of non-commercial aquatic organisms to facilitate the use of acoustic techniques in the waters around Japan. This paper is a representative study.

View full abstract

　Marine product industries in the Tohoku area ware heavily damaged by Tohoku Pacific Ocean off Earthquake. More than 90% of fishing boats （13,271） were washed away or broken in the Iwate Prefecture. 　　And many fisheries facilities such as aquaculture facilities and fish markets, etc. were destroyed in the Iwate prefecture. 　　After the earthquake occurred or the tsunami warning were announced, some fishermen evacuated to offshore and some of them died. In case of Tsunami attack in the future, fishermen may surely evacuate to offshore with their fishing boats at the risk of their lives. 　　Authors performed questionnaire survey targeting the fishermen, who evacuated to offshore with their fishing boats in 2011, among 24 fisheries co-operatives. According to the result of the survey, 22 fisheries co-operatives acknowledged the need of rules for evacuation to offshore. Authors analyzed the results of the questionnaire and tried to clarify problems for establishing the evacuation rule. Authors performed more detailed questionnaire and interviews with fishermen of the Taro-chou fisheries cooperative. The results were as follows. 　　Many fishermen have will of evacuating to offshore, but they don't have enough knowledge such as the tsunami arrival time, the safe depth and area against tsunami current. There is an urgent need to establish a fishing boat refuge rule suited to the characteristic of fishery and fishing boats in Iwate prefecture. Also, it is a serious problem to provide tsunami emergency information promptly to fishing boats in operation.

View full abstract

For a fishing vessel, weather information is necessary to ensure safe navigation and to obtain fishing information. On board, fishers use the information on waves, winds, currents and water temperature on the basis of their experiences. Weather routing is one of the method to determine minimum time route or minimum fuel consumption route by using weather information. Recently, weather routing has become an important concept not only safe navigation but also energy saving for a fishing vessel. Thus, since 2014, we have been researching and developing a high-resolution weather routing system for a fishing vessel. We modified the weather routing system of merchant ships for fishing vessels by using a detailed grid size of weather information and incorporating a short calculation interval. This study examined the possibility to apply the weather routing to an actual fishing vessel, a skipjack pole and line fishing vessel, on the route between fishing port and fish ground, which is offshore of the Boso Peninsula in Japan. We introduced the high-resolution weather routing system on board. The results demonstrate that the weather routing can influence energy efficiency, and assist in fishing trip planning, to decide a departure time for fishing grounds.

View full abstract

We conducted the wind tunnel experiment of the Rotation Flow Turbine developed in Hirosaki University to measure and observed the flow velocity on the coast of Tairadate. As a result, we get the accurate torque coefficient line and max power coefficient 0.06 at λ of 0.25 in wind tunnel experiment. About the experiment of flow velocity on the coast of Tairadate, it was found that the amount of power generation at the shallow depth is high, and it is possible to install the metal halide lamp on trap-net. If the Light-emitting diode （LED） is chosen, it can be installed eight, and that is equivalent to two metal halide lamps. Since the catch of main fish continue to decrease in recent years, the trap-net fishermen hope to develop more effective fishing method to solve this problem. As one of the methods, there is a research result that the catch amount like Japanese horse mackerel was increased by installing a metal halide lamp on the trap-net and utilizing the phototaxis of the fish.

View full abstract

The biomass and density of the kelp Saccharina japonica var. religiosa fluctuates over the years on the southwest coast of Hokkaido. The purpose of this study is to identify the period which water temperature affected on biomass and density of the kelp. Relationships between the biomass and density of the kelp and ten-day mean water temperature （TDMWT） was examined these based on a 2001-2014 monitoring study data-set on biomass and density of algae and sea urchin in June at Oshoro inlet, Hokkaido. Correlation coefficients were calculated to compare between TDMWT from the previous November to next May and the kelp biomass and density in June. There were significant negative correlations between TDMWT in February and the biomass, and TDMWT from January to early March and the density of the kelp in June at the depth of 0.4m, respectively. We consider that low water temperature in the winter season led to an increase in the density and accelerate the growth of the kelp directly and indirectly via oceanographic factors associated with the low water temperature in this period, e.g. nutrient concentration. Furthermore, low water temperature in the spring season influences the biomass and density of the kelp via supplying nutrient by snowmelt.

View full abstract

To improve the accuracy of abundance estimates from acoustic data, it is necessary to determine the catch efficiency of the sampling gear used in combination with the acoustic survey. In this study, we proposed a method to estimate the catch efficiency of framed midwater trawl（ FMT） using acoustic data for juvenile walleye pollock （Gadus chalcogrammus）, one of the dominant species of sound scattering layer in south east area of Hokkaido. Experimental hauls using FMT with black netting were conducted 17 times in nighttime, as a result, juveniles of fork length ranged from 10 to 70 mm was caught. The estimated efficiency by each haul decreased with the fork length increases with sampling periods. Additionally, the efficiency was estimated by the fork length class of 10 mm intervals using multiple regression, then its variation with length showed same tendency with the result mentioned above.

View full abstract

The sea cucumber, Apostichopus armata （Selenka, 1867）, is an important biological marine resource in Hokkaido. We developed a sea cucumber resource management support system using information and communication technology to promote sustainable use of this resource. Fishing information is entered into the system by fishermen using an iPad, and positional information of the ship is recorded by a global positioning system logger and sent to a server, where it is stored. The data output from the server, such as quantity of the resource, natural increase in populations, and catch, can then be viewed by the fishermen throughout the fishing season. The fishermen are thus able to examine the data and adjust the length of the fishing season in order to prevent overfishing. The Rumoi Chiku Namako Bukai of the Shinsei Marine Fishery Cooperative achieved a V-shaped recovery in sea cucumber numbers after the introduction of the support system. In addition, we used the technology developed for the sea cucumber support system to develop a support system for bottom trawling.

View full abstract

　In order to maintain the functions of major facilities of fishing ports covering approximately 5,000km, In addition to properly implementing daily management and repair measures, it is necessary to grasp the situation quickly at the time of the occurrence of a disaster and to carry out measures. 　　In order to make up for lack of human resources and financial resources and to construct a network of public-private partnership collaboration, we have constructed a system that utilizes smartphones that can easily perform inspection work and record accumulation.

View full abstract

As an approach to promote the utilization of ICT of fishing ports, fishing grounds and fishing communities, a database on fishing ground facilities information was experimentally created, and future implementation methods were examined. Concretely, a ledger information database of fishing ground facilities, such as artificial reefs, artificial reefs for nursery, aquaculture facilities, fishing ground preservation facilities, etc. was created, and was linked to geographic information systems （GIS） to visualize the data. As optional information, seaweed bed/tideland distribution, contour line drawings, fishing port/harbor areas, areas with established fishing rights, etc. were recorded. As a library, a system was also constructed so that various drawings, design conditions, stability calculations, surveys on effects, etc. can be linked together, and a trial version was created.

View full abstract