Yoshiki Matsushita

Nagasaki University · Graduate School of Fisheries Science and Environmental Studies

In order to accumulate data on the effects of vessel moorings on the marine ecosystem, we estimated the extent of the area to which the mooring rope of a fisheries training vessel comes into contact with the seabed by measuring the depths of various sections of the mooring rope. It was found that the scoured area of the seabed was up to 11,031.9 m2...

An unmanned surface vehicle (USV) with a fish attraction lamp was developed to assist in the nighttime operations of a Japanese purse seine fishery. The USV weighs about 15 kg, is equipped with a 200 W underwater light-emitting diode (LED), and can be radio-controlled to move on the sea surface. The purse seiner shoots a net to surround the lightin...

Fish occurrences at two anchored fish aggregating devices (FADs) off Goto-Retto Archipelago, Japan that occurred in close proximity, but in different environments, were observed with time-lapse cameras suspended from FADs from May 2019 to October 2020. We confirmed the occurrence of 15 species and 99,997 individuals. The most abundant species were...

The extent and area of seabed swept by fishing gear is necessary information to examine the effects of the fishing on the seabed. We estimated the gear footprint of fly-dragging fishing gear which has not been well studied until now, by measuring its movement. We installed a GPS logger on the fishing boat (80 kW main engine) to determine the its sp...

Many studies have been conducted with the aim of reducing fuel consumption by the fishing industry. We examined whether drag can be reduced by changing the arrangement of gears without requiring the development of new parts for the conventional float and ground gear. Ten differently shaped floats and ground gears were measured in a water flume tank...

Codend selectivity experiments and landed fish measurements at the landing site were carried out to understand the species and sizes of escapees from the codend mesh, retained in the codend and sorted on the deck. We employed otter trawl gear having the conventional 66-mm mesh size codend with a covernet with hoops. Measurements of landed fish were...

We compared the shapes and catches of two trawl nets having differing headrope and groundrope configurations based on paired tow data collected by two research vessels (Yoko Maru and Kumamoto Maru) in the East China Sea. According to the paired data, the vertical opening of the net was significantly higher on the Yoko Maru, which employed a headrop...

We investigated movement pattern of commercial important fish around Offshore Wind Turbine (OWT) and neighboring habitats in Goto Islands. We tagged 55 individuals of 2 fish species and released around the OWT in 2017. (27 Pagrus major from 1st Feb 2017 to 16th Mar 2017 (winter), 8 P. major and 20 Seriola quinqueradiata from 13th July 2017 to 13th...

Nile tilapia Oreochromis niloticus is now the most abundant and commercially important tilapiine in Lake Victoria. From the total of 1 512 fish sampled from commercial gill net fisheries during 2014 and 2015, 809 (54%) were males and 672 (44%) were females, giving an overall sex ratio of 1.20 males: 1.00 females. The mean (± SE) length and weight f...

The development of fishery technologies supports food sustainability to achieve a steady supply of fish and fishery products. However, the priorities for research and development (R&D) in fishery technologies vary by region due to differences in fish resource availability, environmental concerns, and consumer preferences for fishery products. This...

Samples (6404) of Nile perch were collected monthly from commercial catches between June 2014 and June 2015. The total length (cm), weight (g) and sex of fish were all determined in the field, with 3771 (59%) being male and 2059 (32%) being female fish, for an overall sex ratio of 1.83:1.00 (male: female). The average length and weight for all fish...

This study examined the possibility of the LED panels as a fishing lamp system in the coastal squid jigging fishery for swordtip squid and Japanese common squid. Fishing trials were carried out using coastal squid jigging boats (6.6-7.3 t) equipped with LED panels. The catch amounts of squid jigging boats with LED panels (experimental boats) were c...

The present study investigated on Length-weight relationship, Condition factor, Sex ratio, Gonadal Somatic Index (GSI) and Size at Maturity of Omena Rastrineobola argentea. Samples (2240 fish) were collected monthly between August 2014 and March 2015 in the Kenyan waters of Lake Victoria. Results for length-weight relationship revealed that R. arge...

Studies on the diet of Rastrineobola argentea were conducted between August 2014 and March 2015 in the Kenyan waters of Lake Victoria. Stomach contents of 1154 specimens collected from commercial fishers and experimental seining were analyzed. Juveniles of R. argentea under 30 mm SL fed almost exclusively on zooplanktons, while adult fish larger th...

The first author has been operating a squid jig fishing in Tsushima Island, Nagasaki for approximately 30 years since 1980's. Squid jigging fishery has experienced the stagnant squid prices after the asset bubble burst, the lighting power competition among the boats to increase catch amounts and a rise in fossil fuel prices during those 30 years. C...

Fishing experiments were carried out to reduce fuel consumption in pair trawl fishery in the East China Sea. A modified trawl was constructed with thinner twine of ultra-high-molecular-weight polyethylene (Dyneema) for the wings and the main body, except the belly. By using the modified trawl, fuel consumption during towing was significantly reduce...

A 55 W underwater discharge lamp was set in front of the leader-net of a trap-net in Hirado Island, Nagasaki. The light was left on for 4 hours during the nighttime. We observed fish schools around the trap-net by using a scanning sonar. Fish schools were frequently observed around the lamp when lit and tended to move to the entrance of the trap-ne...

Jigging with artificial lights (squid jigging) and deploying of large scale trap-net (also known as a set-net in Japan), are the major methods to capture Japanese common squid Todarodes pacificus in western Japan. Squid jigging is a highly selective fishing method. However, it consumes large amount of energy for steaming to the fishing ground and f...

This study examined the possibility of using underwater lamps in coastal squid jigging fishery Fishing trials were carried out from 2009 to 2011 using coastal squid jigging boats (6.4-6.6 t) equipped with an underwater lamp apparatus with a shade to create high/low light intensity fields in the water column. The catch amounts of the squid jigging b...

Lighting systems combining light-emitting diodes (LEDs) and metal halide lamps (MHs) are expected to be energy-saving tools in Japan’s squid jigging fishery. Previous research has shown the need for light stronger than LEDs (9 kW) and 36 MHs (108 kW) to catch the Japanese common squid Todarodes pacificus. We tested a stepwise lighting method termed...

Application of the low-energy light emitting diode (LED) is considered as a possible measure for fuel saving in the squid jigging fishery. We monitored fuel consumption of 14 coastal squid jigging boats ranging in size from 6.6 to 19 gross tons (GT) operating in the northern and western waters of the Sea of Japan in 2009–2011. In summer in the nort...

Fishing provides high quality seafood and creates employment and income for people worldwide. Most of the capture methods used for fishing are, however, heavily dependent on the use of fossil fuels. For many important fisheries their high consumption of fuel constitutes a major constraint to their economic viability but also represents a significan...

Squid attracting light systems consisting of low power light emitting diode panels (LEDs) and conventional metal halide lamps (MHs) were tested to describe the influence of combinations of LEDs and MHs on squid catch. Fishing trials using LEDs (9 kW) and different numbers of MHs were carried out in August and September 2009 targeting two squid spec...

抄録 定置網の垣網周辺で水中灯を点灯して魚群を滞留させ，明け方前に消灯して魚群を身網へ誘導することで漁獲増加を目指す実験を行った。長崎県対馬の大型定置網の垣網に消費電力 55 W の水中灯を取り付け，点灯日と非点灯日を繰り返す試験を 2007～2009 年の間に 157 日実施した。その結果，点灯時の一日の総漁獲量は，非点灯時よりも多くなった。2007 年はウルメイワシ，2008 年はケンサキイカとブリ類，2009 年はマサバが漁獲物中の優占種で，点灯時のこれらの種の漁獲量は，非点灯時の漁獲量より有意に多くなった。

抄録 中型まき網漁業の灯船のスキャニングソナー画像を解析して，魚群反応の画素数から漁獲結果を予測する実験式を得た。この式を用いて集魚中の魚群に投網した場合に期待される漁獲量（期待漁獲量）を算出し，投網したときと投網しなかったときの期待漁獲量を比較したところ，期待漁獲量の増加とともに投網する確率が高くなった。漁労長は期待漁獲量が 1.5 トン以上の集魚で必ず投網し，50% の確率で投網を行う期待漁獲量は 1.3 トンであった。期待漁獲量が 1.3 トンと 1.5 トン以上の集魚回数はそれぞれ全体の 32% と 24% であった。

Vertical movement of the moon jelly Aurelia aurita was investigated in the southwestern area (5.8〜9.4m deep) of Omura Bay, Nagasaki. We examined the influence of attaching micro data loggers on the behavior of six moon jellies in an aquarium. No significant difference was observed in mean bell pulse frequencies in experimental animals vs. controls...

海中を潜行するエチゼンクラゲをスキューバ潜水により追跡し，深度変化を計測することで，遊泳速力を求めた。傘径 0.6～1.6 m の 14 個体の遊泳速力は，最小 0.07 ms-1，最大 0.17 ms-1 であった。傘径を B とすると，遊泳速力=0.1 B s-1，一拍動あたりの推進距離=0.25 B の関係が求められた。傘径 1～1.5 m の大型個体でも遊泳速力は約 0.1～0.15 ms-1 となるため，対馬暖流の流軸上や強い潮流の中では，流向と逆方向への移動はできないと推測される。また，エチゼンクラゲの遊泳速力は，ほとんどの場合に漁獲対象とする魚類の遊泳速力より小さいと推測される。

The swimming depths of 12 individual Nemopilema nomurai with bell diameters of 0.8-1.6 m were investigated using pop-up archival transmitting tags and ultrasonic pingers, and the validity of the research method was evaluated. The N. nomurai studied frequently showed vertical movement, with the swimming depth ranging from 0 to 176 m, The mean swimmi...

A small number of fishers in Chiba Prefecture of eastern Japan use cotton gill nets to catch Japanese spiny lobster Panulirus japonicus. To examine the advantages of cotton gill nets, we analyzed changes in mesh breaking load of a new cotton gill net used in a fishing operation. A new cotton gill net was also soaked in a seawater tank to simulate g...

Selectivity of a grid separator for marbled flounder Pleuronectes yokohamae and white-spotted conger Conger myriaster was estimated to reduce bycatch of juvenile marbled flounder while retaining commercial sizes of white-spotted conger. Four different grids made of horizontal bars (13, 15, 20 and 24 mm bar spaces) fixed on the belly of the codend w...

マアナゴの漁獲を維持しながらマコガレイ小型魚の混獲を防ぐために,小型底びき網のコッドエンド下部に,水平のバーを配列したグリッドを取り付けた漁具を開発した。そして,バー間隔13,15,20,24mmで曳網試験を実施し,マコガレイとマアナゴに対するグリッドの選択性を調べた。両種に対するグリッドの選択性は,魚体の鉛直方向の厚みとバー間隔の比および魚のグリッドに対する反応という2つの要因を合わせることにより表現できた。また,マコガレイ小型魚がグリッドから逃避する割合は,バー間隔15,20mmでそれぞれ4割,6割と考えられた。 Selectivity of a grid separator for marbled flounder Pleuronectes yokohamae and white-sp...

A parallel haul experiment of two trawl nets equipped with groundropes of different diameters was carried out to understand the role of the groundrope for fishing gear selectivity. The diameter of the groundrope of the test net was 61.3 mm on average, while that of the conventional (control) net was 32.7 mm. The selectivity curve of the test net fo...

To improve the otter board used with a semi-pelagic trawl net, we evaluated the conventional otter board used in Ise-wan Bay and compared the lift and drag characteristics with the following experimental otter board. The experimental otter board was designed to enable both semi-pelagic and bottom trawl operations along with a high lift-drag ratio....

We engaged in development of a semi-pelagic/bottom trawl net mainly for off-bottom species instead of demersal species, for coastal trawl boats in Ise Bay, Aichi, Japan. Bottom contact of otterboards could be controlled by changing warp length. The semi-pelagic/bottom trawl net reduces the area where the gear contacts the seabed more than a convent...

新潟県の小型底びき網漁業を対象に，対象種の漁獲を維持しながら大型クラゲの混獲を防除する装置（JET）を他の混獲防除装置の知見を参考にしながら試作し，現用の網に装着して曳網実験を行った。JET は死亡したエチゼンクラゲの破片の混獲を重量比で 89% 減少させた。一方，漁獲対象となる大型の魚類はすべて袋網で保持された。小型の生物の漁獲は種によって重量比で 0～39% 減少した。ただし，これらの値には袋網とカバーネットの網目選択性の違いが影響し，種によっては過大推定であると考えられた。

We investigated designs of an otter board and two trawl nets, designed to target different species, one for mantis shrimp and one for sea bass, used in Ise-wan Bay, Aichi, Japan. Rectangular nettings of retail products were used to construct two trawl nets to simplify manufacture and repair, and not to leave netting scraps. Results from experimenta...

The reaction behaviour of juvenile Japanese flounder (Paralichthys olivaceus) to towed grids (0.5 X 0.2 m, horizontally, or vertically orientated bars at 10-mm intervals) was observed as a means of understanding fish behaviour in relation to grid selection for a beam trawl fishery in Tokyo Bay. Reaction behaviours were categorized within four patte...

Bycatch and discard are emerging problems in New England region of the United States. A series of meetings with representatives of the fishing industry were held in 10 of the major fishing ports in this region in 2001. The scope of these meetings was to learn about local concerns and incorporate fishermen's unique experience into fisheries science,...

New selective trawl fishing gear have been developed by fishers, administrators, and researchers to mitigate the bycatch and discard problem in a coastal trawl fishery in Choshi, Chiba, in eastern Japan. As a result, the selective fishing gear that has a two-level codend with the Bycatch Exclusion Window (BEW) at the top panel of the upper-bag was...

A trawl net of which the codend has the two-level construction of two bags; the upper bag for target species and the lower bag for marine debris, was developed with the bycatch exclusion window (BEW) at the top panel of the upper-bag to reduce bycatch and labor force for on-deck sorting. Fishing experiments of this trawl net were carried out in a c...

The experimental operations were carried out by a distant water small trawler in the North Pacific Ocean to research accumulation process for walleye pollock Theragra chalcogramma and atka mackerel Pleurogrammus monopterygius in the trawl. Fourteen pocket-nets were attached from wings to the codend to investigate how fish accumulate between the net...

A series of fishing trials for development of species separation devices to separate shrimp and unwanted juveniles of finfishes was carried out for coastal trawlers in Choshi, Chiba. Double codends with a separation panel were designed and four types of separation panel (43.5 mm/bar square mesh, 55.0 mm/bar square mesh, 24.6 × 49.8 mm rectangular m...

The fishing reports of one trawler from 1989 to 1994 covering 4499 hauls were analyzed to understand the catch characteristics of distant water small trawl operating in the Russian EEZ. Among 11 market categories of catch species, the sum of six categories reached 91.2% of the total catch. The catch composition of each haul was observed to have the...

Detailed measurements of fish captured by trawl were made to determine the relationships between codend mesh size and on-deck sorting selectivity at Kuala Kedah, on the west coast of Peninsular Malaysia. Major species landed in this area are Indo-Pacific mackerel (Rastrelliger brachysoma), Jewfish (Sciaenidae), threadfin bream (Nemipteridae) and sq...

Square mesh codend selectivity experiments for walleye pollock Theragra chalcogramma were carried out along the Pacific coast of the Kuril Islands and off Miyagi, Tohoku. Selection curves varied by differences in body shape. Catches taken off Miyagi tended to retain smaller individuals when compared with catches using the same codend mesh size off...

Mesh selectivity experiments were carried out using single and double codends in order to reduce the capture of small sizes of fish by northern trawlers in the Pacific coast of the Kuril Islands in September 1991. The mesh selectivity of the single codend was compared with that of the double codend commonly used in the experimental area. The estima...

The migrating behaviour of fish schools such as jack mackerel Trachurus japonicus, spotted mackerel Scomber australasicus, and Japanese anchovy Engraulis japonicus was investigated in set-net fishing grounds by means of sonar image records. The spotted mackerel and Japanese anchovy schools moved at an average speed of 18-19cm/s, while the jack mack...

The retinal adaptations were examined for the walleye pollock Theragra chalcogramma taken at different times of day and night from different depths of trawling in the north Pacific. Even in the daytime, some retina sampled from depths of 150 to 200m showed a tendency towards dark adaptation. This suggests the inactive response of the walleye polloc...

Fish behaviour surveys in the Nayaura set-net fishing ground off Mie prefecture were carried out in relation to the fish leading effect of the natural bank.The topography of the fishing ground was surveyed by a side-scan-sonar and characterized by a long bank surrounded by large and small rocky reefs, which extend parallel to the leadernet from the...

The muscle twitch contraction time of Walleye pollock Theragra chalcogramma was measured in relation to fish size and muscle temperature, on board a Northern trawler in the Okhotsk Sea. The contraction time was defined as the time period from the electric pulse of 2ms wide and 5-20V, to the peak of muscle twitch contraction. The scale effect was ob...

Smallmouth bass Micropterus dolomieu is an alien species in Japan, and it has a serious crisis of biodiversity because it eats other fish, insects, etc. avariciously. A master curve of mesh selectivity of gillnets used to pest control smallmouth bass was estimated with a maximum likelihood method. Bi-normal model was selected and the curve skewed i...

We conducted a parallel haul experiment using 2 offshore trawl fishing boats in Chiba Prefecture to examine a performance of the raised footrope trawl fishing gear. One boat employed a conventional trawl net and another employed the raised footrope trawl net. They towed nets in same fishing ground at same time. Headrope heights for both nets and bo...

平成19年度長崎大学水産学部公開講座「環境共生の水産学-持続可能な海と魚の利用をめざして」2007年12月15日, 長崎