DOCSLIB.ORG

琵琶湖におけるニゴロブナ Carassius Auratus Grandoculis 種苗の 放流水域としてのヨシ帯の重要性と放流事業の課題

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
琵琶湖におけるニゴロブナ Carassius Auratus Grandoculis 種苗の 放流水域としてのヨシ帯の重要性と放流事業の課題 Nippon Suisan Gakkaishi 77(5),822833 (2011) 琵琶湖におけるニゴロブナ Carassius auratus grandoculis 種苗の 放流水域としてのヨシ帯の重要性と放流事業の課題 藤原公一，1,2a臼杵崇広，1a 根本守仁，1 松尾雅也，3 竹岡昇一郎，3 田中 満，3 北田修一2 （2011 年 2 月 23 日受付，2011 年 5 月 15 日受理） 1滋賀県水産試験場，2東京海洋大学海洋科学部，3琵琶湖栽培漁業センター The importance of the reed zone as a release region for larval and/or juvenile nigorobuna Carassius auratus grandoculis in Lake Biwa, and problems for stock enhancement KOH-ICHI FUJIWARA,1,2aTAKAHIRO USUKI,1a MORIHITO NEMOTO,1 MASAYA MATSUO,3 SYOICHIRO TAKEOKA,3 MITSURU TANAKA3 AND SHUICHI KITADA2 1Shiga Prefecture Fisheries Experiment Station, Hikone, Shiga 5220057, 2Faculty of Marine Science, Tokyo University of Marine Science and Technology, Minato, Tokyo 1088477, 3Stock Enhancement Center of Lake Biwa, Kusatsu, Shiga 5250005, Japan EŠective release strategies for nigorobuna Carassius auratus grandoculis in Lake Biwa were investigated by release-recapture experiments of otolith marked nigorobuna with ALC. As a result, nigorobuna arrived at the juvenile stage exceeding approximately 16 mm in standard length and released to the Phragmites australis reed zone showed a rapid increase in survival rate. A remarkable decrease in the survival rate of stocked ˆsh in the lake was observed in cases of 1) releasetothereed-freelakeshore,2) reduction of the depth of ‰ooded reed zone ac- cording to draw down of water level by artiˆcial manipulation, 3) growthretardationofreedinspringbyexces- sive cutting management of reed in winter, and 4) excessive release of nigorobuna larvae to a limited reed zone. Larvae-release techniques which overcome the problems and reed zone-independent release methods for nigorobuna should be developed in the future. キーワードALC 耳石標識，再捕率，生残率，ニゴロブナ，標識放流，琵琶湖，放流効果，ヨシ帯 ニゴロブナ Carassius auratus grandoculis は，コイ科 ことが明らかになった。6) また，ヨシ帯奥部は本種仔魚 フナ属に属する琵琶湖の固有亜種13)で，滋賀県の食文 が好んで摂餌する微小甲殻類（ミジンコ亜綱)69)が豊富 化を代表するフナズシ4,5)の材料に用いられる。このた で，貴重な摂餌の場となっているが，溶存酸素濃度が著 め本種は琵琶湖漁業にとって非常に重要な漁獲対象とな しく低く，一般には魚類が生息しにくい環境にあること っており，琵琶湖ではその資源を積極的に増やすため， が判った。6) しかし本種仔魚は生理的にそのような貧酸 琵琶湖栽培漁業センターと滋賀県漁業協同組合連合会に 素環境に適応しており，ヨシ帯奥部は本種仔魚にとって よって種苗放流事業が行われている。著者らは，この事 捕食者からの退避地として機能していると考えられ 業を効果的に進めるうえで必要な種苗放流適地について た。6,10) それでは，本種の仔魚や稚魚が琵琶湖で生き残 知見を得るため，本種の養成親魚から得た仔稚魚をよく るうえでヨシ帯は不可欠であろうか。この疑問を解決す 発達したヨシ帯に放流して初期生態を調査した。その結 るため著者らは，ALC（アリザリンコンプレクソン） 果，本種は仔魚期にはヨシ帯の岸辺付近（以下，奥部） で耳石に標識（以下，ALC 標識)11,12)を付けて識別した へ積極的に集まり，その水域を発育の場として利用する ニゴロブナ種苗を琵琶湖のヨシ帯，近隣の砂浜およびそ Tel81749281611．Fax81749252461．Emailfujiwara-koichi＠pref.shiga.lg.jp a 現所属滋賀県水産課（Shiga Prefecture Fisheries Management Division, Otsu, Shiga 5208577, Japan） ニゴロブナ種苗放流の適地と課題 823 れらの沖合水域へ放流し，琵琶湖で再捕調査を行い，本 県水産試験場（以下，滋賀水試。滋賀県彦根市）へ搬入 種仔稚魚が琵琶湖で生き残るうえでヨシ帯が非常に重要 し，琵琶湖水を流したパンライト製または FRP 製の水 な役割を果たしていることを示した。また，ヨシ帯への 槽に収容管理して，数日後にふ化仔魚を得た。これら ALC 標識種苗の放流調査により，高い放流効果が期待 ふ化仔魚は藤原13)の手法に従って飼育した。種苗各群 できる種苗サイズ（発育段階）を明らかにし，併せて， の生産概要は Table 1 にまとめた。 ヨシ帯が持つ本種仔稚魚のナーサリー機能は，治水を目 標識 種苗の耳石（礫石）に藤原11)および藤原ら12) 的とした琵琶湖の人為的な水位低下やヨシ帯の管理を目 の方法で ALC 標識を付けた。なお，放流後に再捕され 的とした冬季のヨシ刈り取り，焼き払い，およびヨシ帯 る種苗の放流時の礫石の長径（以下，耳石長）を推定す への過度の種苗放流によって低下することを明らかにし るため，原則として最終の標識操作は各群とも放流する た。 前日から放流直前までの 24 時間かけて行い，放流時の 種苗の耳石外縁を ALC で染めた。Table 1 には種苗各 材料および方法 群へ付けた ALC 標識についても併せて示した。 供試魚 1992 年から 1995 年にかけて，毎年原則と ヨシ帯の重要性の検討 ニゴロブナの種苗放流適地と してニゴロブナの産卵盛期の 5 月上旬に，琵琶湖栽培 してのヨシ帯の重要性を検討するため，Fig. 1 に示した 漁業センター（以下，栽培漁業センター。滋賀県草津市） 滋賀県長浜市湖北町海老江（以下，海老江）の琵琶湖沿 のニゴロブナ親魚養成池へ人工産卵藻（キンラン，川島 岸のヨシ帯（Site E），近隣の同町尾上（以下，尾上） 商事）を設置して，ニゴロブナに自然産卵させた。産卵 の砂浜（Site O）およびそれらの沖合（竹生島の南方） 翌日には，卵が付着した人工産卵藻を活魚輸送車で滋賀 の水深約 80 m の水域（Site CS）へ本種種苗 94E 群， Table 1 Details of the ALC marked1 nigorobuna Carassius auratus grandoculis released in Lake Biwa Standard length Group Spawning Hatching Release Number Release Age at release ALC mark type2 name date date date released site 3 Mean±SD N DAH4 mm 92M11 5/11/1992 5/17/1992 5/19/1992 2 Dot 5.53±0.32 124 1,074,000 M 92M12 5/11/1992 5/17/1992 5/27/1992 10 Dot and ring 7.61±0.95 100 295,000 M 92M13 5/11/1992 5/17/1992 6/ 6/1992 20 Dot and 2 rings 9.73±1.43 135 49,000 M 92M14 5/11/1992 5/17/1992 6/16/1992 30 Dot and 3 rings 15.12±2.47 113 26,000 M 92M15 5/11/1992 5/17/1992 6/26/1992 40 Dot and 4 rings 16.06±2.80 140 29,300 M 92M21 6/11/1992 6/15/1992 6/17/1992 2 Dot 5.74±0.42 112 313,000 M 92M22 6/11/1992 6/15/1992 6/23/1992 8 Dot and ring 6.99±0.47 129 193,000 M 92M23 6/11/1992 6/15/1992 7/ 1/1992 16 Dot and 2 rings 8.07±0.92 142 199,000 M 92M24 6/11/1992 6/15/1992 7/ 9/1992 24 Dot and 3 rings 10.67±1.48 180 91,000 M 92M25 6/11/1992 6/15/1992 7/17/1992 32 Dot and 4 rings 14.76±2.72 124 25,800 M 94E 5/ 9/1994 5/15/1994 6/26/1994 42 5 rings 16.63±3.65 250 132,000 E 94O 5/ 9/1994 5/15/1994 6/26/1994 42 4 rings 15.47±3.52 250 121,000 O 94CS 5/ 9/1994 5/15/1994 6/26/1994 42 3 rings 17.62±4.31 250 98,000 CS 94M 5/ 9/1994 5/15/1994 6/28/1994 44 3 rings 18.14±4.50 240 95,000 M 95M 4/29/1995 5/ 5/1995 7/ 6/1995 62 3 rings 20.62±3.62 244 30,000 M 95C1 5/25/1995 5/31/1995 7/ 6/1995 36 Dot and 2 rings 16.80±3.69 289 84,000 C 95C2 4/29/1995 5/ 5/1995 7/ 6/1995 62 2 rings 20.62±3.53 257 32,000 C 93E 5/12/1993 5/18/1993 7/ 1/1993 44 4 rings 16.22±3.30 203 194,000 E 95E 5/15/1995 5/20/1995 7/ 4/1995 45 3 rings 17.28±3.34 323 37,000 E 95CN1 5/15/1995 5/20/1995 8/ 1/1995 73 3 rings 23.30±6.06 218 17,000 CN 95CN2 5/4/1995 5/10/1995 8/ 1/1995 83 6 rings 25.52±6.14 200 66,000 CN 95H 5/15/1995 5/20/1995 7/11/1995 52 4 rings 15.97±3.37 314 120,0005 H 95A 5/15/1995 5/20/1995 7/11/1995 52 3 rings 16.47±3.71 323 109,0006 A 1 Refer to the text for ALC marking. 2 Except for the mark of only a dot, ALC marks were mutually discriminable from the size, interval, etc. of rings. 3 Refer to Fig. 1. 4 Days after hatching. 5 Non-marked ˆsh of 81,000 (23.21±SD3.70 mm in standard length) were released with marked group 95H. 6 Non-marked ˆsh of 506,000 (20.13±SD3.19 mm in standard length) were released with marked group 95A. 824 藤原，臼杵，根本，松尾，竹岡，田中，北田 94O 群および 94CS 群を，ともに 1994 年 6 月 26 日に 放流した。沿岸部への放流種苗（94E 群，94O 群）は， 滋賀水試から活魚輸送車で群毎に放流水域付近まで運搬 し，バケツリレーして放流した。沖合への放流種苗 （94CS 群）は，尾上にある朝日漁港で活魚輸送車から 漁船の活魚水槽へ移し替えて沖合まで運搬して放流し た。なお，放流時に各群から 250 尾を無作為抽出して 冷凍保存し，後日，解凍後，これら全個体の標準体長 （以下，体長）を測定して群毎に平均値と SD を計算す るとともに，体長 2mm間隔の相対度数を求め，同群の 放流尾数にこれを乗じて，体長 2mm間隔毎の放流尾数 を推定した。同年 11 月 5 日から翌年 4 月 15 日には， 琵琶湖の北湖盆（北湖）で小型機船底曳き網を用いてニ ゴロブナ標本を 13,525 尾採集した。その標本を冷凍保 存し，後日解凍して体長と体重を測定した後，耳石を調 べて標識魚を特定し，さらに各群を確定して，群毎の再 捕尾数を求めた。また，各群の耳石の最外部の ALC リ ングの長径（＝放流時の耳石長）を蛍光顕微鏡（OP- TIPHOT，XTEFD，ニコン）の接眼マイクロメータ Fig. 1 Release sites of nigorobuna Carassius auratus を用いて計測し，藤原らの方法12)で群毎の耳石長体長 grandoculis. Nigorobuna with diŠerent ALC mark shown in Table 1 were released in each site. 関係式から個体毎に放流時の体長を推定し（以下，この 体長を推定放流体長という。），推定放流体長 2mm間隔 で再捕尾数を求めた。これらのデータから，群毎および 定，標識確認を行い，92M12～92M15 群と 92M22～ 各群の推定放流体長 2mm間隔の再捕率（再捕尾数/放 92M25 群の群毎の再捕率を算出した。 流尾数×100，）を計算した。 また，これら放流種苗のうち，92M10 シリーズの放 ヨシ帯内での放流サイズ毎の生残率の推定 藤原ら6) 流魚は 92M14 群を放流した 8 日後の 1992 年 6 月 24 日 はヨシ帯におけるニゴロブナの初期生態を知るため，滋 以降に，92M20 シリーズの放流魚は 92M24 群を放流 賀県近江八幡市牧町（以下，牧，Fig. 1）の琵琶湖沿岸 した当日の 7 月 9 日以降に，同ヨシ帯の両端と中央部 に自生するヨシ帯（幅が概ね 150～160 m，奥行きが概 に岸辺から沖合にかけて設置した 3 枚のネットの先端 ね 45～50 m）に，ALC 標識を付けた 10 群のニゴロブ に設置したマス網で捕獲されるようになった。92M11 ナ仔稚魚を放流した。この内，5 群は 1992 年 5 月 17 ～92M14 群と 92M21～92M22 群は，それまでヨシ帯 日にふ化したもので，滋賀水試内で継続飼育しながら異 内部でタモ網で採集されたが，マス網では採集されなか なるパターンの ALC 標識を付けて，2 日齢，10 日齢， ったことから，それぞれ 6 月 23 日以前および 7 月 8 日 20 日齢，30 日齢および 40 日齢の時点で Table 1 に示 以前はそのヨシ帯内に限定して生息していたと考えられ したとおり順次放流した（本報では，それぞれ 92M11 ている（藤原ら6)）。そこで，6 月 24 日時点で未放流の 群，92M12 群，92M13 群，92M14 群および92M15 92M15 群を除く 92M10 リーズおよび 7 月 9 日時点で 群。以下，92M10 シリーズ）。また，他の 5 群は同年 6 未放流の 92M25 群を除く 92M20 シリーズの各群の牧 月 15 日にふ化したもので，同様に ALC 標識を付けて 2 のヨシ帯内での生残率を，これらの採集尾数のデータを 日齢，8 日齢，16 日齢，24 日齢，32 日齢の時点で放流 用いて田中14)，北田15)にならい，Fig. 2 に示したモデル した（それぞれ92M21 群，92M22 群，92M23 群， にしたがって推定した。ここで Ri は，i 番目に放流した 92M24 群および 92M25 群。以下，92M20 シリーズ）。 92M10 シリーズまたは 92M20 シリーズの種苗の放流 このうち，92M11 群と 92M21 群の標識はともに卵段 尾数，Ei＋1 は（i＋1）番目に放流した 92M10 シリーズ 階で付けた耳石（礫石）の核部分が点状に発光する標識 または 92M20 シリーズの種苗の放流時点（i＋1）にお であるため両者を識別ができないが，他の群の標識はそ ける i 番目の放流群の生残尾数である。ここで i 番目に れぞれ識別できる。そこで，今回の調査では 1992 年 10 放流した種苗と（i＋1）番目に放流した種苗の（i＋1） 月 15 日から翌年 4 月 6 日にかけて琵琶湖北湖で小型機 時点以降の生残率は等しく，それら種苗のマス網による 船底曳き網を用いて 21,459 尾のニゴロブナ標本を採集 捕獲割合も等しいと仮定して，i 番目に放流した 92M10 し，得られた標本を上記と同様に保存して，後日，測 シリーズまたは 92M20 シリーズの種苗の次の群の放流 ニゴロブナ種苗放流の適地と課題 825 Fig. 2 Schematic diagram of survival estimation of larval and juvenile nigorobuna Carassius auratus grandoculis in the reed zone (Site M in Fig. 1). 時点（i＋1）の生残尾数を次式で求めた。なお，ci と た。 n ci＋1 は，それぞれ 92M10 シリーズ（6 月 24 日以降）ま ÂS T, n＋1＝_ Âq i, i＋1, (n＝2, 3) たは 92M20 シリーズ（7 月 9 日以降）の i 番目と（i＋ i＝1 1）番目の放流群のマス網で再捕された尾数である。 この分散は，同様にデルタ法によって 2 2 Ri＋1ci V ( ÂS T,3)q 23V ( Âq 12)＋〈Âq 12V ( Âq 23) ÂE i＋1＝ ci＋1 ＋2 Âq 12 Âq 23 Cov ( Âq 12, Âq 23) これらの生残尾数から，i 番目に放流した 92M10 シ および 2 2 2 2 リーズまたは 92M20 シリーズの種苗の次の群の放流時 V ( ÂS T,4) Âq 23 Âq 34V ( Âq 12)＋ Âq 12 Âq 34V ( Âq 23) 〈 2 2 2 点（i＋1）の生残率 Âq i, i＋1（以下，群間生残率）を次式 ＋ Âq 12 Âq 23V ( Âq 34)〈＋2 Âq 12 Âq 23 Âq 34 Cov ( Âq 12, Âq 23) 2 で計算した。 ＋2 Âq 12 Âq 23 Âq 34 Cov〈( Âq 12, Âq 34) 2 ÂE i＋1 Ri＋1ci ＋2 Âq 12 Âq 23 Âq 34 Cov ( Âq 23, Âq 34) Âq i, i＋1＝ ＝ Ri Rici＋1 と推定される。ここでは，異なる期間の生残は互いに独 なお，群間生残率の漸近分散はデルタ法（例えば北田16) 立と仮定し，共分散の項を無視して分散を計算した。 を参照）によって一次の項まで展開して次式で推定した。 1992 年 5 月 11 日には，同ヨシ帯の中央において， 2 2 R i＋1 V (ci) c i V (c i＋1) 岸辺から沖合方向への距離と水深を実測し，その後の水 V ( Âq i, i＋1) 2 2 ＋ 4 R i [ c i＋1 c i＋1 位の変動に伴う水に浸かったヨシ帯（以下，水ヨシ帯） 〈 ci の奥行きの変化を計算した。 －2 3 Cov (ci, ci＋1) c i＋1 ] 効果的放流サイズの検討 琵琶湖での高い放流効果が ここで，V (ci)＝Ripâ i(1－pâ i), pâ i＝ci/Ri,〈V (ci＋1)＝Ri＋1 期待できる種苗サイズを検討するため，Fig.
Load more

Recommended publications
  • Distinct Herpesvirus Resistances and Immune Responses of Three
    Gao et al. BMC Genomics (2017) 18:561 DOI 10.1186/s12864-017-3945-6 RESEARCH ARTICLE Open Access Distinct herpesvirus resistances and immune responses of three gynogenetic clones of gibel carp revealed by comprehensive transcriptomes Fan-Xiang Gao1,2, Yang Wang1, Qi-Ya Zhang1, Cheng-Yan Mou1,2, Zhi Li1, Yuan-Sheng Deng1,2, Li Zhou1* and Jian-Fang Gui1* Abstract Background: Gibel carp is an important aquaculture species in China, and a herpesvirus, called as Carassius auratus herpesvirus (CaHV), has hampered the aquaculture development. Diverse gynogenetic clones of gibel carp have been identified or created, and some of them have been used as aquaculture varieties, but their resistances to herpesvirus and the underlying mechanism remain unknown. Results: To reveal their susceptibility differences, we firstly performed herpesvirus challenge experiments in three gynogenetic clones of gibel carp, including the leading variety clone A+, candidate variety clone F and wild clone H. Three clones showed distinct resistances to CaHV. Moreover, 8772, 8679 and 10,982 differentially expressed unigenes (DEUs) were identified from comparative transcriptomes between diseased individuals and control individuals of clone A+, F and H, respectively. Comprehensive analysis of the shared DEUs in all three clones displayed common defense pathways to the herpesvirus infection, activating IFN system and suppressing complements. KEGG pathway analysis of specifically changed DEUs in respective clones revealed distinct immune responses to the herpesvirus infection. The DEU numbers identified from clone H in KEGG immune-related pathways, such as “chemokine signaling pathway”, “Toll-like receptor signaling pathway” and others, were remarkably much more than those from clone A+ and F.
    [Show full text]
  • Chapter 2 Healthy Interaction Between Human and the Earth
    FY2010 Part 1, Chapter 2 －Healthy Interaction between Human and the Earth Chapter 2 Healthy Interaction between Human and the Earth As seen in Chapter 1, we humans depend on under- which remained until today heavily depend on them ground resources such as fossil fuels and minerals, as (Figure 2-1-1). well as renewable resources such as food, forest and In Chapter 2, we will consider about how to achieve water. These natural resources provide energy, food, the wisdom in order to assist local everyday lives timber, medicine and so on, which are vital for human which based on traditional knowledge, to maintain the beings. We also depend on the fundamental roles of relationship in good condition between human beings and ecosystems; healthy forests, for example, regulate the Earth’s environment and to share the benefits of damages from heavy rainfall caused by typhoons. These ecosystem services with the future generation, focusing natural resources and ecosystems support various on status of renewable resources of biodiversity. patterns of human life styles, and indigenous cultures Section 1 Benefits of Ecosystem Services on the Earth for Our Everyday Lives There are 1.75 million identified species. Including Here, we will discuss the relationship between our unknown living organisms, it is said that there are 30 everyday lives and ecosystem services of biodiversity, million species on the Earth. Humans are nothing more mainly from the perspective of how ecosystem services than one of the many species, and it would be impossible provide security in everyday life, timbers for building, for us humans to exist without interrelationship with food, medicine for our health, and traditional cultures in these innumerable living organisms.
    [Show full text]
  • Ecological Notes of the Fishes and the Interspecific Relations Among Them in Lake Biwa
    Ecological Notes of the Fishes and the Interspecific Relations among Them in Lake Biwa Taizo MIURA Introduction Lake Biwa has been much interested by biologists, specially by ichthiologists because of the richness and variety of the lake fish fauna and of their diverse origin. Therefore, a good number of papers on taxonomic researches of the fishes have been published. However ecological studies of the fishes have been poorly made. Freshwater environments as well as terrestrial ones have been practically reformed, accompanied with development of human society and specially of industries and agriculture. Lake Biwa is also not an exception. Recently the ministry of construction is planning to construct a dam between the north basin and the south basin of the lake, and to pump up water from the north basin to the south one for the purpose of holding a continuous water supply to the outlet river. By such programme the two basins will nearly be disconnected and the water level of the north basin is often expected to be lowered. It can be easily expected that production of the organisms in the lake will be affected by the reformation, so that it 'is important to predict how the organic production will be affected, and to propose how the programme should be made in order to benefit the local people, especially the fishermen. Thus, about sixty scientists including biologists, physicists, chemists and agricultural economists had formed a co-operative research team and have investigated the biotic re- sources of the lake from 1962 to 1965. Through this investigation ecological studies of some of the fish species have been intensively made.
    [Show full text]
  • Lake Biwa Experience and Lessons Learned Brief
    Lake Biwa Experience and Lessons Learned Brief Tatuo Kira, Retired, Lake Biwa Research Institute, Otsu, Japan Shinji Ide*, University of Shiga Prefecture, Hikone, Japan, [email protected] Fumio Fukada, Retired, Shiga Prefectural Government, Otsu, Japan Masahisa Nakamura, Shiga University, Otsu, Japan * Corresponding author 1. Introduction The history of the lake’s management is also one of confl icts over water utilization and fl ood control between Shiga This brief outlines the major management issues for Lake Biwa, Prefecture and the central government or the downstream the largest freshwater lake in Japan. The lake and its watershed mega-cities, including Kyoto, Osaka and Kobe. The Lake Biwa communities have enjoyed a common history for thousands of Comprehensive Development Project (LBCDP), the largest years, fostering a unique lake culture in the surrounding area. The birth of the lake can 6HDRI-DSDQ 1 be traced back to some four million years ago. As one of few ancient lakes in the world, /<RJR it embraces a rich ecosystem, with fi fty-seven endemic species being recorded. At DNDWRNL5 7 $QH5 the same time, it is a principal /$.(%,:$ ,PD]X <2'25,9(5%$6,1 1DJDKDPD water resource in Japan, $GR5 1RUWK%DVLQ -$3$1 supplying drinking water for 14 'UDLQDJH%DVLQ%RXQGDU\ million people in its watershed 3UHIHFWXUH%RXQGDU\ /DNH 5LYHU %LZD +LNRQH and downstream areas. /DNH Additionally, its catchment 6HOHFWHG&LW\ 6+,*$ area is highly industrialized NP 35() and urbanized, being inhabited .DWDWD 2PL +DFKLPDQ (FKL5 by approximately 1.3 million . .<272 DWVXUD5 +LQR5 people, with the population 35() ,/(& still increasing at one of the .\RWR 6RXWK%DVLQ 2WVX .XVDWVX highest growth rates in Japan.
    [Show full text]
  • Difference in the Hypoxia Tolerance of the Round Crucian Carp and Largemouth Bass: Implications for Physiological Refugia in the Macrophyte Zone
    Short Report Difference in the hypoxia tolerance of the round crucian carp and largemouth bass: implications for physiological refugia in the macrophyte zone Hiroki Yamanaka1**, Yukihiro Kohmatsu2, and Masahide Yuma3 1 Center for Ecological Research, Kyoto University, 2-509-3 Hirano, Otsu, Shiga 520-2113, Japan 2 Research Institute for Humanity and Nature, 457-4 Motoyama, Kamigamo, Kita-ku, Kyoto 603-8047, Japan 3 Department of Environmental Solution Technology, Faculty of Science & Technology, Ryukoku University, 1-5 Seta-Oe, Otsu, Shiga 520-2194, Japan * Present address: Research Institute for Humanity and Nature (RIHN), 457-4 Motoyama, Kamigamo, Kita-ku, Kyoto 603-8047, Japan (e-mail: [email protected]) Received: August 28, 2006 / Revised: November 28, 2006 / Accepted: December 1, 2006 Abstract The hypoxia tolerance of larval and juvenile round crucian carp, Carassius auratus gran- Ichthyological doculis, and largemouth bass, Micropterus salmoides, was determined using respirometry to examine the potential of hypoxic areas in the macrophyte zone as physiological refugia for round crucian carp. Research The tolerance, which was measured as the critical oxygen concentration (Pc), was 1.32 mg O /l in the ©The Ichthyological Society of Japan 2007 2 round crucian carp and 1.93 mg O2/l in the largemouth bass. As the round crucian carp tolerated Ichthyol Res (2007) 54: 308–312 hypoxia better than the largemouth bass, hypoxic areas in the macrophyte zone might function as physiological refugia for round crucian carp. DOI 10.1007/s10228-006-0400-0 Key words Hypoxia tolerance · Critical oxygen concentration (Pc) · Physiological refugia · Carassius auratus grandoculis · Micropterus salmoides or many larval and juvenile fi shes, the macrophyte early life history (Miura, 1966; Yuma et al., 1998).
    [Show full text]
  • Development of Sense Organs and Mouth and Feeding of Reared Marble Goby Oxyeleotris Marmoratus Larvae*
    Fisheries Science 60(4), 361-368 (1994) Development of Sense Organs and Mouth and Feeding of Reared Marble Goby Oxyeleotris marmoratus Larvae* Shigeharu Senoo,*1 Kok Jee Ang,*1 and Gunzo Kawamura*2 *1 Faculty of Fisheries and Marine Science , Universiti Pertanian Malaysia, 43400 UPM, Serdang, Selangor, Malaysia *2Faculty of Fisheries , Kagashima University, Shimoarata, Kagoshima 890, Japan (Received August 23, 1993) To obtain the fundamental information required toooestablish an artificial seed production technique for the marble goby Oxyeleotris marmoratus, the development of sense organs and mouth and the feeding of the larvae were observed. The larvae exhibited a S-posture and horizontal swimming at 2 days after fertilization (d AF) and commenced feeding on phytoplankton (species unknown) at 3 d AF when the eyes, the otic vesicle with ciliated epithelium, the free neuromasts on the head and the trunk, and the ciliated olfactory epithelium were functional. The first taste buds appeared in the oral cavity at 6 d AF after the onset of feeding on Brachinous spp. The larvae commenced feeding on Cyclops sp. at 7 d AF, Moina sp. at 10 d AF, and Anemia salina nauplii at 15 d AF. This change of feeding might be due to the development of the mouth and mobility of larvae rather than the development of sense organs. At 20 d AF, the larvae developed free neuromasts on the caudal fin. Twin cones and rods appeared in the ratinae at 30 d AF when the larvae changed in phototaxis from positive to negative. The larvae became benthic in habit at 35 d AF.
    [Show full text]
  • News Release（研究成果情報） 氷
    News Release（研究成果情報） H29.8.18 氷 見 市 学芸員の研究論文が農学で権威のある国際誌に掲載！ ～水田のプランクトンがイタセンパラを救う～ 概要 国の天然記念物で絶滅の危機に瀕している淡水魚イタセンパラは、水田から排水されるプラン クトンによって保護されていることが、氷見市教育委員会学芸員らの研究により解明されました。 氷見市教育委員会の西尾正輝主任学芸員の研究グループは、2010 年から 2012 年にかけて伝統 的な用排兼用（※1）河川である万尾川のイタセンパラの生息状況を調べたところ、イタセンパ ラの個体数は河川周辺の水田面積や草刈りによって決まることを見出しました。その理由として、 豊富な動物プランクトンを含む水が、水田から万尾川へ排水されること。地域住民による米害虫 対策の河岸の草刈りが、日当たりを作り出すこと。これらの 2 点によりイタセンパラの餌や生息 地が提供されていることが明らかになりました。 これらの成果をまとめた論文は、世界的に評価の高い国際誌「Agriculture, Ecosystems & Environment」（※2）の電子版に 8 月 7 日（現地時間）に掲載されました。 図１．水田からの河川への動物プランクトン 図２．イタセンパラの生息に必要な環境条件 の供給がイタセンパラの生息に有効 今後への期待 今回の成果は、生物多様性が一体となった伝統的な農業システムの好事例として、 氷見市が目指す「世界農業遺産」への登録に大きく寄与するものと思われます。これ からの稲作は、生産者の高齢化や高収益作物への転作に伴い、厳しさを増していくと 思われます。人と自然に優しい伝統的な循環 型農業を維持するために、 スマートフォ ンで水田水管理コストを削減する最新の管理手法を用いるなど、伝統的農業システム と革新的管理手法を融合させることで、 今後もイタセンパラ生息河川周辺（万尾川） の「米作り」の継続を期待したい。 お問合せ先：ひみラボ水族館（電話）９１－２２４９ （メール）[email protected] 担当：氷見市教育委員会 教育総務課 西尾 正輝 補足説明 論文執筆者（筆頭著者）： 氷見市教育委員会 西 尾 正 輝 主任学芸員（37歳） 論文名：Paddy management for potential conservation of endangered Itasenpara bitterling via zooplankton abundance （動物プランクトンを介した絶滅危惧種イタセンパラの潜在的な保全のための水田管理） 著 者：西尾正輝（氷見市教育委員会）・江戸謙顕（文化庁）・山崎裕治（富山大学） 雑誌名：Agriculture, Ecosystems & Environment（ ア グ リ カ ル チ ャ ー エ コ シ ス テ ム ズ エ ン バ イ ロ ン メ ン ト ） 本研究は、文化庁、富山県および河川財団の助成を受けて実施されました。 ※ 1 用 排 兼 用 ・ ・ ・ 用水路と排水路の機能をもつ 。ほ場整備の影響により、伝統的な「用 排 兼 用 」 は 減 少 し 、 大部分が用水路と排水路を分離させた「用排分離」となっている。 ※ 2 Agriculture, Ecosystems & Environment・・・科学雑誌の重要度を示す指標インパクトファクターにおいて、農業学際分 野を扱う英雑誌56誌の中で1位（IF値 4.099）のトップジャーナルです。 図３．Agriculture, Ecosystems ＆ Environment の電子版（8 月 7 日に電子版に公開されました）
    [Show full text]
  • Predation by Crucian Carp Larva/Fry Visualizes Biological Interactions of Paddy Field Community
    Predation by crucian carp larva/fry visualizes biological interactions of paddy field community Taisuke Ohtsuka & Shigehumi Kanao Introduction Carassius auratus grandoculis (nigorobuna in Jap- anese) is a crucian carp endemic to Lake Biwa, and it is used as an ingredient in Funa-zushi (lac- to-fermented fish) that has been the specialty food of Shiga prefecture, Japan. In recent years, however, its catch has declined drastically. The increase in carnivorous fishes intro- duced from North America (Micropterus salmoides and Lepomis macrochirus), reed community decline, and artificial water level regulation are possible causes of the marked decline. Because it can also reproduce in paddy fields, About 30 days old juveniles of Carassius au- breeding their larvae/fry in the paddies have been ratus grandoculis grown in a paddy field. carried out with the aim of reviving the stock. Two More than five times in length, and 500 times in weight of the newly hatched larva. ways of breeding are now conducted. One is stock- ing larvae in paddies, and another is constructing 15-44 days of age in body weight. This retardation fish pass from drainage to paddies for the run of of growth suggests deficient of preferable foods (see their adults. below). Ejecting juveniles to the drainage connect- We conducted some experiments to confirm ing to Lake Biwa in time with mid-season drainage the function of paddies as a nursery of the carp, and (usually about 40 days after transplanting of rice those to examine the impact of the larvae/fry stock- plant) is, therefore, appropriate for their stock en- ing on the paddy field ecosystem (Kanao et al.
    [Show full text]
  • Multiyear Use for Spawning Sites by Crucian Carp in Lake Biwa, Japan
    Journal of Advanced Marine Science and Technology Society, Vol. 24, No. 2, pp. 19–30, 2018 Original Paper Multiyear use for spawning sites by crucian carp in Lake Biwa, Japan Yoshio Kunimune*1, Yasushi Mitsunaga*2 *1 Graduate School of Agriculture, Kindai University, 3327-204 Naka-machi, Nara, Nara, 631-8505, Japan *2 Faculty of Agriculture, Kindai University, 3327-204 Naka-machi, Nara, Nara, 631-8505, Japan, [email protected] Received: July, 10. 2018, Accepted: October, 19. 2018 Abstract From April 2008 to July 2009, an acoustic telemetry study on crucian carp was conducted in Lake Biwa, Japan. Twenty Nigorobuna, ten gengoroubuna and one ginbuna captured during spawning seasons were released with ultrasonic transmitters in the South Basin. Signals from the tagged fish were detected by 28 ultrasonic-receiver stations installed around Lake Biwa. Seasonal preference of habitats was examined by distance-based analysis. Seasonal distributions of nigorobuna and gengoroubuna in Lake Biwa were observed including consecutive two spawning seasons. It was revealed that seasonal migration patterns of nigorobuna and gengoroubuna were different. Nigorobuna appeared mainly around the release site all the year round, while gengoroubuna migrated to the North Basin after their spawning season, where they stayed during the non-spawning season, and moved to the South Basin in the next midwinter, where they stayed until the end of the next spawning season. It was also revealed that gengoroubuna preferred lower water temperature than nigorobuna. Gengoroubuna moved faster than nigorobuna and ginbuna. There were high-degree correlations in distance ratios of each station during spawning seasons in the release year and the next year in both nigorobuna and gengoroubuna, suggesting a multiyear use for the same spawning site.
    [Show full text]
  • Carassius Ve Střední Evropě
    MASARYKOVA UNIVERZITA Přírodovědecká fakulta Ivo PAPOUŠEK MOLEKULÁRNĚ-GENETICKÉ ANALÝZY DRUHŮ RODU CARASSIUS VE STŘEDNÍ EVROPĚ Přílohy k disertační práci Školitel: prof. RNDr. Jiřina Relichová, CSc. Školitel-specialista: RNDr. Věra Lusková, CSc. Brno, 2008 PŘÍLOHY – SOUBOR PUBLIKACÍ Příloha I Papoušek, I., Vetešník, L., Halačka, K., Lusková, V., Humpl, M. & Mendel, J. (2008). Identification of natural hybrids of gibel carp Carassius auratus gibelio (Bloch) and crucian carp Carassius carassius (L.) from lower Dyje River floodplain (Czech Republic). Journal of Fish Biology 72, 1230-1235. Příloha II Vetešník, L., Papoušek, I., Halačka, K., Lusková, V. & Mendel, J. (2007). Morphometric and genetic analysis of Carassius auratus complex from an artificial wetland in Morava River floodplain, Czech Republic. Fisheries Science 73, 817-822. Příloha III Papoušek, I., Lusková, V., Halačka, K., Koščo, J., Vetešník, L., Lusk, S. & Mendel, J. (2008). Genetic diversity of the Carassius auratus complex (Teleostei: Cyprinidae) in the central Europe. Journal of Fish Biology (submitted 10/2008). Příloha I Papoušek, I., Vetešník, L., Halačka, K., Lusková, V., Humpl, M. & Mendel, J. (2008). Identification of natural hybrids of gibel carp Carassius auratus gibelio (Bloch) and crucian carp Carassius carassius (L.) from lower Dyje River floodplain (Czech Republic). Journal of Fish Biology 72, 1230-1235. Journal of Fish Biology (2008) 72, 1230–1235 doi:10.1111/j.1095-8649.2007.01783.x, available online at http://www.blackwell-synergy.com Identification of natural hybrids of gibel carp Carassius auratus gibelio (Bloch) and crucian carp Carassius carassius (L.) from lower Dyje River floodplain (Czech Republic) I. PAPOUSˇEK*, L. VETESˇNI´K,K.HALACˇKA,V.LUSKOVA´,M.HUMPL AND J.
    [Show full text]
  • In Lake Biwa
    79 Countermeasures against Alien Fishes (Largemouth Bass and Bluegill) in Lake Biwa Atsuhiko IDE＊ and Shinsuke SEKI＊ Abstract Lake Biwa is one of the world's most ancient lakes, with an origin going back four million years. Many aquatic organisms, including more than 30 endemic species or subspecies of fish and molluscs inhabit the lake, and various kinds of fisheries have targeted those animals for centuries. Bluegill (Lepomis macrochirus) and largemouth bass (Micropterus salmoides) were first found in Lake Biwa in 1965 and 1974. While bluegill spread gradually through the shallow water zones and into small lagoons surrounding the lake, largemouth bass increased explosively in the 1980s. Simultaneously, native fishes such as crucian carp and bitterlings disappeared from the coastal shallows. After that, the population of bluegill began to increase. In recent years, bluegill has comprised over 90% of the fish fauna in Lake Biwa's south basin. Since 1985, fishermen have been trying continuously to reduce these alien species by several means. Fishing gear such as Eri (a set-net), gill nets, and pulling nets have been used. Recently, over 400 metric tons per year of these alien fishes have been eliminated. At the same time, the Shiga Prefectural Fisheries Experimental Station has tried to develop more effective gear to catch them. We have devised a pot trap, with its top covered by a sheet to provide shade, for efficient capture of the alien fishes, and a small beam trawl for use in beds of submerged aquatic vegetation. Other methods for the eradication of the alien fishes are currently under study.
    [Show full text]
  • Japan March 2009
    Fourth National Report to the United Nations Convention on Biological Diversity Japan March 2009 Chapter 1 Overview of Status, Trends, and Threat to Biodiversity 1. Biodiversity in Japan 1.1 Features of biodiversity in Japan 1.2 Status of threatened wildlife 1.2 Review of the Red List 2. Structure of the biodiversity crisis in Japan 2.1 First crisis (brought about by human activities and development) 2.2 Second crisis (brought about by reduced human activities) 2.3 Third crisis (brought about by artificially introduced factors) 2.4 Crisis brought about by global warming 3. Biodiversity in each geographical area 3.1 Natural mountain areas 3.2 Satochi-satoyama areas/countryside 3.3 Urban areas 3.4 River/wetland areas 3.5 Oceanic/coastal areas 3.6 Island areas Chapter 2 Status of National Biodiversity Strategy 1. National Biodiversity Strategy in Japan 1.1 The background of the formulation of the Third National Biodiversity Strategy 1.2 Structure and character of the Third National Biodiversity Strategy 1.3 Targets and Basic Policies for National Strategy (1) Three targets (2) Grand design for the National Land and the Centennial Plan (3) Five basic perspectives (4) Four basic strategies (5) 2010 Biodiversity Target and the National Biodiversity Strategy 1.4 Check and Review of the National Strategy 1.5 Basic Act on Biodiversity of Japan and the National Strategy 2. Implementation of the National Biodiversity Strategy 2.1 Measures and policies for national land area (1) Ecological Network (2) Conservation of priority areas (3)Nature restoration (4)Agriculture, Forestry and Fisheries (5)Forests (6) Countryside and satochi-satoyama areas (7) Urban Areas (8) Rivers and wetlands (9) Coastal Areas and Oceanic Areas 2.2 Cross-sectional and fundamental measures (1) Protection and management of wildlife (2)Sustainable Use of Genetic Resources (3) Promotion and implementation (4) International Cooperation (5) Information management and technology development (6) Measures against global warming (7) Environmental Impact Assessment 3.
    [Show full text]