In order to understand the capture process of trolling line, the fish behavior to an artificial bait of trolling line was observed by a towed underwater video camera. Experimental trolling line consisted of a towing line, a towed underwater video camera, a leader, an artificial bait, and a hook. The experimental trolling line was towed by a small boat at 3 to 6 knots, and the underwater video image were recorded on VCR. A total of 38 hours of the underwater video image were recorded during the experimental period, and the fish behavior to the artificial bait of trolling line could be observed clearly. Fish species that could be identified, were mackerel Scomber spp., frigate mackerel Auxis rochei, amberjack Seriola dumerili, dolphinfish Coryphaena hippurus, yellowtail Seriola quinqueradiata, blowfish Lagocephalus wheeleri, and mullet Mugil cephalus. Fish behavior patterns were classified as follows: appearance into the camera view, approach to the artificial bait, attack on the artificial bait, touching the artificial bait, being hooked, and captured. The total number of appearance into the camera view was 1364, in which the capture was only 23 due to the low attack response frequency to the approaches. From these results, fishing efficiency of the experimental trolling line which is defined as the ratio of the total number of capture to the total number of appearance was calculated to be 0.020 for mackerel, 0.018 for frigate mackerel, and 0.012 for amberjack.
Following severe increases fuel oil price, the Fisheries Agency and the National Federation of Fisheries Co-operation Associations (JF-zengyoren) issued a booklet on fishing vessel fuel conservation. In this booklet, the writers stressed that fishing vessel operators should maintain optimum vessel trim and reduce payloads to minimize fuel consumption. However, concrete fuel consumption measurements were not provided. In this study, experiments aimed at measuring the fuel consumption of a semi-planing hull type fishing vessel were conducted to evaluate the fuel-conservation effects resulting from variations in payload and vessel trim. Results showed that 1) a 1.5L/h per 100kg payload relationship existed between payload and fuel consumption at vessel speeds above 7knots, whereas under 6knots no such correlation existed, and fuel consumption was dependent only on speed; 2) varying vessel trim by lowering the bow increased fuel consumption, while varying the trim by lowering the stern deceased fuel consumption.
In order to investigate the behavior of the pen shell Atrina lischkeana under aerobic and hypoxic conditions, the valve movement of these pen shells was recorded using the strain gauge method. The experiments were carried out from December 17 to 26, 2002. Two patterns of valve movement were recorded under aerobic conditions: multi-close-open action and single close-open action. The multi-close-open action is characterized by a series of close-open actions, which are repeated at interval of less than 30 seconds. This action was observed during the burrowing behavior of the pen shell. The single close-open action is characterized by a close-open action that occurs at intervals greater than 4 minutes; this action occurs during vomiting behavior. The single close-open action occurred more frequently under hypoxic conditions than under aerobic conditions, and a high frequency of this action was associated with creep-out behavior. These results indicate that the characteristics of valve movement may be a good indicator of pen shell physiology under aerobic and hypoxic conditions.
In Japan, publish of 'Isoyake Taisaku guideline' (Fisheries Agency 2007) broke through the blocked status in seaweed restoration on the deforested areas. The guideline introduced the adaptive management and collaboration among fishermen, administrative, researcher and citizen, and strongly recommended flexible soft techniques instead of irretrievable hard techniques such as stone piling and deployment of concrete blocks. In a subsequent project (2007-2009), policy and contents of the guideline were popularized by lectures in >50 local meetings and restoration of seaweed beds were practiced in model areas. Introduction of a chief supporter (organizer, specialist, diving instructor, etc.) resulted in the successful recovery of algal communities in several urchin barrens. For administrative and researchers new to seaweed bed management, a training course was held once a year. Besides, official annual meeting is also held to share information on current status of isoyake, restoration and monitoring techniques. As sustainable practices are needed for the maintenance and extension of restored seaweed beds, education and increase of participants, improvement of skills and functioned flow are needed.
The reforestation were tried on barren grounds in Onagawa Bay, Miyagi Prefecture according to the Isoyake Taisaku Guideline (Fisheries Agency). Hearing to fishermen clarified the deforestation occurred on three types of bottom, bedrock, boulders and artificial reefs. Kelp culture and transplantation (spore bag, suspended float, caged or exposed on the bottom) revealed that the persistence of barren state is not caused by short of algal propagules nor water quality but due to heavy grazing by herbivores including sea urchins, gastropods and sea hares. To determine the reforestation sites and area sizes, bottom topography and number of participants were considered in addition to fishermen's proposal. Removal of herbivores by citizen divers resulted in the restoration of kelp/Sargassum beds on an exposed bedrock, but not on a sheltered boulder bed. Junior high school students also contributed to map the distribution of urchin barrens, to estimate the amount of kelp growing on shellfish culture ropes and to demonstrate the improvement of gonads by feeding the kelp to empty sea urchins. A committee comprised of industrial, public and scientific members along with fishermen worked well, but further sustainable activities are needed to reduce the barren grounds.
Restoration of seaweed bed was challenged at a block (10×10m) of Diadema barren on the northwestern coast of Izu Peninsula. Monthly removal of Diadema was started in April 2007 and followed by repeated enclosures using sand bag curtain, gill nets and plastic sheet or rolled gill nets. Seaweeds (but no Sargassum) grew on the barren boulders from winter to spring. When the nets were fouled, bended or broken, Diadema often invaded the enclosures. In the enclosure, Sargassum horneri juveniles (20cm high) fixed on mid-layer floats on December 2008, grew up to 6m in height and matured in February 2009. S. horneri recruited on the seafloor (boulders) in late May 2008, but were grazed by invaded D. setosum and gastropods. S. horneri juveniles transplanted in October 2008 were browsed by herbivorous fish in a month. However, S. horneri juveniles (covered with honeycombed PET) and S. pilutiferum juveniles transplanted in December 2008 could grow and mature. To supply more abundant juveniles, S. piluliferum was installed in the mid-layer net and suspended at a height of 1m from the sea bottom. As the result, the matured S. piluliferum could supply hundreds of germlings around the net.
The urchin barren has increased and maintained along the coasts of Kochi Prefecture, Japan. In these urchin barrens, Anthocidaris crassispina and Echinometra spp. dominate on bedrock and boulders. Algal succession and density of invading sea urchins were studied after removing sea urchins at five stations (Kamikawaguchi, Ikenoura, Kutuu, Tei and Sakamoto). In 2009, fishermen, students and volunteers removed sea urchins by skin and scuba diving at Kutuu. Sargassum duplication, S. assimile and S. tenuifolium growing in adjacent areas colonized coralline covered bottoms within a year. Removal of sea urchin was the most effective method to regenerate seaweed bed at Kamikawaguchi, Kutsuu and Ikenoura. In contrast, at Tei and Sakamoto, we also have to reduce the browsing activity of herbivorous fishes. Sustainable cooperative activities are needed among fishermen, students and volunteers.
At Nagoya, Saiki City, Ooita Prefecture, where 'Isoyake' has occurred since about 1997, elevated water temperature as well as grazing by urchins and herbivorous fish were thought to be the causes of the phenomenon. However, removal of sea urchin by seven fishermen could restore seaweed beds. After that, an elementary school collaborated to make and deploy 'spore bags' for supplying Sargassum embryos. Both pupils and their teachers enjoyed the instruction of the course, which was announced by mass media. Ensuring the participant safety is the most important.
Since 1995, disappearance of seaweed beds so-called Isoyake became conspicuous at Ooseto, west coast of Nishisonogi Peninsula, Nagasaki Prefecture. The local fishermen and collaborators made efforts to recover Sargassum beds from July 2007 to May 2009. The short-term destination was reforestation in 0.2-hectare areas. As the main factors of Isoyake were assumed to be intensive grazing by sea urchins and/or herbivorous fishes, and short of algal reproductive bodies, reduction of the density of sea urchins and supply of Sargassum embryos were planned. In the 0.3ha areas, 14,600 sea urchins were removed and fences were laid to prevent invasion of sea urchins at the boundary. Mature Sargassum thalli were transplanted on the sea bottom using the 'open spore bags' made of nonwoven cloth. In addition, nets were set to capture floating mature Sargassum thalli to enhance the recruits. After nearly a year later, the treated area was covered with Sargassum and other seaweeds. The fishermen were encouraged by the success and much more motivated for further reforestation.
Along the rocky shores in Shi-Mie, Nagasaki Prefecture, seaweed beds have decreased since 1990's and urchin barrens are extensively common. To recover seaweed beds, we removed sea urchins and supplied 'seeds' of seaweed in an area of 7,000m^2 in 2008. The total number of sea urchin removed in one year is 25,700 (Anthocidaris crassispina 19,700 and Diadema spp. 6,000) Six hundreds thallii of Sargassum were deployed with modified spore bags on the bottom from spring to summer. Drifting seaweeds were abundantly captured by modified surface gill nets and supplied 'seeds' for the urchin-removed area. In December 2008, the density of juvenile Sargassum (5〜10mm in length) was higher in the urchin-removed area (422.4ind./m^2) than that in the control area (136.0ind./m^2). In May 2009, Sargassum beds were established in the urchin-removed area while the control area continued to be a barren ground.
Fisheries Senior High School, Fisheries Cooperative and Prefectural Fisheries Technology and Development Center collaborated to restore Sargassum beds in an deforested area off Ibusuki City, Kagoshima Prefecture. For training of SCUBA diving, 15-18 students and instructors of the high school dived into the area and removed diadematid sea urchins (mostly Diadema D. savignyi) from there. From 2005 to 2009, they removed more than 60 thousand urchins on 10 days in total. In addition, Fishermen in the cooperative set the mature Sargassum by sticking them into mid-layer gill nets on the bottom. Fisheries Technology and Development Center could recognize the restoration of some Sargassum beds.
Diadema setosum is one of the warm water species of sea urchins forming urchinbarren in southern Japan. D. setosum is seldom eaten because of its peculiar bitterness of the gonads. However, in Kagoshima and Kumamoto Prefectures in Kyushu, southern Japan, D. setosum is caught by the local diving fishermen and the gonads are eaten as sashimi by the local people. The object of this paper is to explain why the supply and demand of D. setosum goes on in the prefectures. The investigation has revealed the mechanism of keeping the supply and demand as follows. Aspect of supply, there is only a fishery for D. setosum from December to March, which diving fishermen can earn modest gains. Aspect of distribution, processor-cum-wholesalers fulfill a role to connect fisheries with markets. Aspect of consumption, product of D. setosum has good things which are cheaper and longer expiration date than other sea urchins and made in Japan. Furthermore, the defect for the taste of D. setosum is filled the gap by peculiar soy source which is sweet and thick and is been fond by people in Kyusyu.
Kyphosus vaigiensis is a herbivorous fish of which meat was hardly favored by most fishermen and anglers because of its bad smell although the species has been consumed in very limited areas. In southern Japan, K. vaigiensis has sometimes caused deforestation by browsing seaweeds. To decrease its population by fishing, utilization of its meat should be promoted. In this paper, there are presented 18 tasty recipes, dishes which were highly evaluated by taste samplers. Good pretreatments and use of spices seem to be the keys to deminish the bad smell.