On the western coast of Hokkaido, Japan, kelp beds dominated by Saccharina japonica var. religiosa are restricted to shallow waters and spatially separated from offshore urchin-dominated barren grounds. We investigated the spatial distribution of kelp zoospores, water currents, and the distribution of kelp beds at Tomari on the coast. Zoospore motility was evaluated in the laboratory at water temperature 7.5, 10.0, 12.5, 15.0, and 17.5℃. At the sea surface, water current direction ranged mainly from northward to westward with velocities of 3.2-6.2 km・day^<-1> (estimated by current meter) and 2.5-3.8 km・day^<-1> (estimated by drifting buoys). Zoospore motility at water temperature in November at Tomari was estimated at 12 hr. Based on the data of drifting buoy and zoospore motility, the maximum potential distance of zoospore dispersal was estimated as 1.3-1.9 km. On the other hand, kelp zoospores were detected at a maximum distance of 1200 m from the closest kelp source population in cultures using sampled seawater. Zoospore densities rapidly declined with increasing distance from the source kelp bed. This study demonstrated that the dispersal potential of the kelp zoospore is more restricted than previously thought.
The purpose of this study was to examine the appropriateness of applying a process study and time study to fishery work. Samples were four kelp farming management bodies that agreed with research in Fukushima, Hokkaido. The bodies were analyzed using the process study and time study. The process study defined 14 processes and bottle neck element work. The time study calculated the standard working time for each element works. From these results, the working time of bottle neck processes for each management body was estimated and compared to the measured working time. As a result, the ratios of measured working time to estimated working times in the management bodies were 86%, 95%, 99%, 101%. In conclusion, the estimated working times agreed well with the measured working times. This suggests that fishery working time can be estimated with high accuracy. This study demonstrated the effectiveness of applying a process study and time study to fishery work.
It is well known that migratory birds use an inverse V-shaped formation to reduce the energy consumption of following birds. In the same way, it is possible for a fleet of fishing vessels to minimize their total wave resistance, and thus save energy, by determining the most efficient formation. Although this is the same type of wave interaction problem faced by multihull ships, the fishing fleet has a large degree of freedom in the positioning of every vessel. In addition, it is expected to become a multi-modal problem, and the solution will require a global optimization technique. In this paper, we try to find the global optimal solution for this fleet formation problem using repulsive particle swarm optimization. Although it proved impossible to find the global optimum, we obtained two converged solutions with substantially fewer trials by separating the optimization process into two stages.
Recently, the fuel price for fishing vessels have increased, as a result, the current balance of them have deteriorated. As a countermeasure for reducing fuel consumption, introduction of the wind-power generator was examined to the fishing vessels. When introducing the generator, it is necessary to consider the generated electric power as well as increase the output of the propulsion engine. To estimate the energy balance of the wind power generator and propulsion engine in the vessel and to determine the relationship between wind velocity and the generated electric power, we measured the force as the drag that works leeward of the wind power generator. The generated electric power of and the varying output of the propulsion engine were estimated from the data about the wind velocity and wind direction measured during the 33rd voyage of our university's research vessel, Umitakamaru. The results indicated that the energy balance was improved because the output of the propulsion engine decreased although the generated electric power reduced when the vessel ran leeward. In contrast, when the vessel ran windward, the energy balance deteriorated because the output of the propulsion engine increased although the generated electric power increased. We clarified the range of the apparent wind direction where the wind power generator stopped working.
Based on lessons from the Great East Japan Earthquake disaster, the countermeasures of fishing port facilities against earthquakes and tsunamis have been carried out selectively, depending on the outbreak frequency and the scale, furthermore in consideration of the role of the fishing port and the function of fishing port facility. The essential points of countermeasures of fishing port facilities against earthquakes and tsunamis are as follows. 1) The Fisheries Agency have ranked countermeasures against earthquakes and tsunamis as main policy, have showed basic direction of countermeasures to fishing port management bodies, have actively promoted countermeasures of fishing port facilities against earthquakes and tsunamis. 2) The fishing port facilities were not completely destroyed by the tsunami attack that is stronger than the design external force even if damaged, and were requested to be "robust and tenacious structure" to somehow keep its function until leading to complete destruction. 3) It is very important to examine countermeasures such as the multiple-protection that combined embankments with breakwaters for disaster prevention or disaster reduction in fisheries area.
Secular function deteriorations of artificial fishing ground facilities are due to physical, chemical, biological factor, fishing activities and so on. From function deterioration surveys and functional recovery works on fishing grounds facilities, the following findings were obtained. At first, the confirmation of function deteriorated facilities has been made possible by using newest equipment or methods for marine observation. Secondly, the range achieved functional recovery of fishing ground facilities are limited to shallow waters such as seaweed beds, tidal flats and so on. In this paper, the confirmation methods of function deterioration of artificial fishing grounds facilities, hardware or software functional recovery methods have been introduced based on the specific case.
AITEF (Association for Innovative Technology on Fishing Ports and Grounds) gathered "harbor facilities function preservation plan explanation and case of a preservation measure about a steel structure [steel prevention food method of construction, steel repair means of reinforcement work and large-scale repair method of construction]" in October, 2014. This report mentions the outline about the contents.
The main function of the sewerage facilities of fishing village are purification and collection of sewage. The lifespan of mechanical or electrical equipment that make up the sewerage facilities is 15-20 years and short. With the increase of in-service life of sewerage facilities, the increase in repair costs by the trouble is remarkable. In view of the LCC (Life Cycle Cost), the shifts from "breakdown maintenance" to "preventive maintenance" are very essential. Several researches to establish consolidate the systems of drawing the function maintenance plan of sewerage facilities have been carried out since 2011. Based on the knowledge obtained through these established plans, the important matters of the function maintenance plan of sewerage facilities have been shown in this paper.
Existing fishing port facilities form a huge stock for which deterioration diagnosis and repair construction have started throughout Japan. Hence a simple and precise method for the deterioration diagnosis is needed. This study aimed to develop a simple deterioration diagnosis method applicable to fishing port facilities, and a proposed method using impact-echo was extensively tested through the inspection of existing structures. The results provided a quantitative measure of the immediacy of countermeasures and a simple deterioration diagnosis method for proper selection of detailed inspection. Availability of the proposed method was confirmed through tests at existing fishing port facilities.
The fishery infrastructures such as fishing port facilities are base of steady supply of marine products, have been maintained continuously and chiefly. Now, the finance of central or local government is very severe in Japan. It is necessary for public facilities administrator to perform both effective and strategic maintenance for prolonging lifetime and reduction of LCC (life cycle cost). In future, the maintenance and replacement of public facilities must be performed by preventive maintenance rather than breakdown maintenance. The deterioration countermeasures were evaluated, performed as main policy of "Basic plan for fisheries" and "Long-term plan for development of fishing ports and ground" by Fisheries Agency. "Basic plan for prolonging lifetime of public infrastructure" indicating the directionality of long-term maintenance was announced by Japanese government in November, 2013. "Action plan for prolonging lifetime of fisheries infrastructure" as medium-term and long-term action to execute steady maintenance was announced by Fisheries Agency in August, 2014. This paper will introduce outline of action plan.