WEKO3
アイテム
伊豆諸島北部海域におけるタカベの資源学的研究
https://fra.repo.nii.ac.jp/records/2010838
https://fra.repo.nii.ac.jp/records/20108388f22980d-4b1d-4bf4-aed3-62f5f4f8d1d6
| 名前 / ファイル | ライセンス | アクション |
|---|---|---|
fra_k_18_167.pdf (13.9 MB)
|
.png)
|
| Item type | 紀要論文 / Departmental Bulletin Paper(1) | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 公開日 | 2024-10-02 | |||||||||||
| タイトル | ||||||||||||
| タイトル | 伊豆諸島北部海域におけるタカベの資源学的研究 | |||||||||||
| 言語 | ja | |||||||||||
| タイトル | ||||||||||||
| タイトル | A study on the population dynamics of yellowstriped butterfish in the waters around the northern part of the Izu Islands. | |||||||||||
| 言語 | en | |||||||||||
| 言語 | ||||||||||||
| 言語 | jpn | |||||||||||
| キーワード | ||||||||||||
| 言語 | en | |||||||||||
| 主題Scheme | Other | |||||||||||
| 主題 | yellowstriped butterfish; age; growth; otolith; abundance estimation | |||||||||||
| 資源タイプ | ||||||||||||
| 資源タイプ識別子 | http://purl.org/coar/resource_type/c_6501 | |||||||||||
| 資源タイプ | departmental bulletin paper | |||||||||||
| アクセス権 | ||||||||||||
| アクセス権 | open access | |||||||||||
| アクセス権URI | http://purl.org/coar/access_right/c_abf2 | |||||||||||
| 著者 |
亘, 真吾
× 亘, 真吾
WEKO
733
|
|||||||||||
| 抄録 | ||||||||||||
| 内容記述タイプ | Abstract | |||||||||||
| 内容記述 | The yellowstriped butterfish, Labracoglossa argentiventris, inhabit shallow waters over rocky bottoms along the Pacific coast from Kyusyu Island to the Boso Peninsula. This stock is important to coastal commercial fisheries in the northern part of the Izu Islands, which use bulk net, gill net, seine and set net to catch this resource. Assessment and management of the stock are necessary for its effective utilization. This thesis focuses on the population dynamics and stock assessment of yellowstriped butterfish, such as age and growth, standardization of catch per unit effort （CPUE）, and abundance estimation, to provide information for fisheries resource management. In Chapter 2, a method to determine the age of yellowstriped butterfish using from the otolith was studied. The edge of the opaque zones as a ring mark on sectioned sagittal otoliths was used. Monthly changes in the marginal growth rate and proportion of appearance of ring marks on the edge of the otolith were examined. Formation of the first ring was observed during spring or summer, corresponding to one and a half years after hatching. Thereafter, one ring was formed each year in the same season as the previous year. In Chapter 3, age, growth and maturity were examined using samples collected in the waters around the northern part of the Izu Islands from 1994 to 2003. Age distribution was estimated from the otoliths and scales. Age distribution determined from the scales resulted in an underestimation compared to the values from the otolith analysis. The comparison of multiple age determination indicated that within reader bias of otolith was smaller than that of scale. Growth was investigated by fitting the von Bertalanffy growth model to the age-length data and the allometric growth model to the length-weight data using maximum likelihood methods. Because the number of small sized fish was insufficient, all parameters could not be estimated by areas （Izu Oshima Island, Toshima Island ～ Shikinejima Island, Kouzushima Island）. The selected von Bertalanffy growth model, based on the Akaike Information Criterion （AIC）, was the differential asymptotic length and variance by area and sex, and growth coefficient by sex. The growth of yellowstriped butterfish was fast until 2 years of age. The estimated asymptotic length of females was larger than that of males. The estimated asymptotic length in the southern part of the study area was larger than that in the northern part of the study area. The effect of the difference of ageing character, otolith or scale, on the growth curve was investigated. Age before 1 year old fish was determined using the large differences in fork length between the older fish, so ageing character was not used. Because the growth speed of large sized fish was slow, age-length relationship was almost same after 4 years of age. For these reasons, difference between the two growth curves was much smaller. The selected allometric growth model, based on the AIC, was multiplicative error structure of differential sex in parameters. The monthly change of the value of Gonadosomatic Index was high from September to December, spawning season, and the peak was October. The maturity rate of 1 year old was 15% and that of after 2 years old was 100%. In Chapter 4, standardization of CPUE was carried out to improve the reliability of the abundance index. To estimate a year effect, any other factors that may influence CPUE were removed from index by using the generalized linear model. Landing in weight by each operation of gill net of Izu Oshima Island, seine from Toshima Island to Shikinejima Island, and bulk net of Kouzushima Island were obtained from 1991 to 2003 by landing slips. Data of sea surface temperature and current pattern of Kuroshio were also obtained for the same period. Because there was little information about movement in the study area, two hypotheses were considered about the movement after recruitment, the case to move from one island to other islands, and the case that there is no movement among islands. Year, month, area, fishing methods, sea surface temperature, and current pattern of Kuroshio were incorporated as main effects and two-way interactions. For each area, the best model was statistically selected by the AIC from all candidate models. The year effect of standardized CPUE was calculated by least squared mean. The trend of relative abundance of yellowstriped butterfish has remained at the same level after 1991. In Chapter 5, stock size of yellowstriped butterfish was estimated by the tuning virtual population analysis based on two hypotheses about the movement among islands using the catch at age and CPUE data. The previous study of rearing experiment showed that probability of agreement of true age by using data from otoliths was higher than that from scales. In addition, previous chapter also indicated that within reader bias for otoliths was lower than that for scales. For these reasons, the otolith ageing was considered to be true for catch at age estimation, and the bias in scale ageing was corrected for the basis for otoliths. The standardized CPUE was used as an abundance index for the tuning. Parameters were estimated by the least squares method and standard error was also estimated by the bootstrap method using resampling data of CPUE and catch at age. The yearly change of stock size of yellowstriped butterfish in the northern part of the Izu Islands after 1998 ranged from 600 to 700 metric tons. The catch rate of this stock ranged from 20 to 30%. The estimated standard error of the stock size became larger in recent years. Coefficient of variation of stock size in 2003 was 0.2. The selectivity of older fish was higher than that of younger fish. This result suggests that the target of this fishery is large sized fish which are high priced, and fishing intensity of small sized fish is low. The estimated stock size, fishing mortality, and selectivity, using two hypotheses of the movement shows the same trends. A similar conclusion of the stock management plan was possible. The percent spawning per recruitment was about 50% in 2003 in each area. The results showed that if the fishing effort is increased from the present level, the amount of catch of large sized fish would decrease, although the total amount of catch would increase slightly. The present level of fishing mortality is close to F0.1. Yield per recruit and spawning per recruitment analysis also suggested that the current level of exploitation is not overfishing. For the sustainable use of yellowstriped butterfish stock, both the current level of fishing effort and low fishing intensity on younger fish should be maintained. | |||||||||||
| 言語 | en | |||||||||||
| 抄録 | ||||||||||||
| 内容記述タイプ | Abstract | |||||||||||
| 内容記述 | タカベ Labracoglossa argentiventris は，九州から房総半島にいたる太平洋岸の岩礁域に生息し，伊豆諸島の沿岸漁業において多く漁獲される。伊豆諸島北部海域において年間の魚種別水揚げ重量，金額ともに1位の主要漁獲物であり，当資源の持続的利用を確保することは，地域の水産業においても重要な課題である。本研究はタカベの年齢や成長，単位努力量あたり漁獲量（CPUE）の標準化，資源量推定などの資源学的研究により，資源の現状評価や資源管理に必要な基礎的情報を得ることを目的とする。第二章は，従来年齢査定に使用されていなかった耳石について，年齢形質としての有効性を検証した。伊豆大島周辺海域で収集したタカベの耳石の不透明帯の外縁を輪紋とし，縁辺成長率と縁辺部の輪紋出現割合を調べた。輪紋は，生後1年半の春から夏にかけて第1輪が形成され，その後1年に1本ずつ同時期に形成されると判断した。第三章は，1994～2003年に伊豆諸島北部海域で収集した標本を用いて，年齢，成長，成熟について調べた。耳石と鱗の輪紋を計測し輪紋数組成を求めた。輪紋数の出現頻度を比較した結果，耳石より鱗の輪紋数が過小に推定される傾向があった。また，耳石と鱗の読み取り誤差を比較した結果，査定値の精度は耳石の方が高かった。成長を把握するため，年齢－尾叉長関係の von Bertalanffy 成長式と，尾叉長－体重関係のアロメトリー式を推定した。小型魚のサンプルが不十分であったため，全てのパラメータを地区別に推定することは出来なかったが，赤池情報量規準（AIC）より極限体長と分散を大島，利島～式根島，神津島の地区別と性別に，成長係数を性別に推定したモデルが選択された。成長は生後2歳頃まで急速に進み，雄より雌が，また伊豆諸島北部海域で南側の島ほど大型に育つことが示された。耳石と鱗の年齢査定値の違いが成長曲線に与える影響を検討したが，1歳まで体長組成から年齢査定が可能なことに加え，高齢になると成長が緩やかになり年齢と尾叉長の関係があまり変化しないため，推定される成長曲線はほとんど同じであった。アロメトリー式は AIC より，性別に推定した乗法誤差構造のモデルが選択された。生殖腺指数（GSI）の値は，産卵期の9～12月にかけて他の時期より高く，ピークが10月に現れた。同時期の成熟率は，満1歳で15%，満2歳以上でほぼ100% だった。第四章は，CPUE に含まれる年変動以外の要因を取り除き，資源量指数としての信頼性を高めるため，一般化線形モデルを使用し標準化を行った。1991～2003年の大島の刺網，新島の寄網，神津島の建切網の水揚伝票と，水温と黒潮流路の情報を収集した。島間の移動に関して，伊豆諸島北部海域全体で移動がある場合と，大島，利島～式根島，神津島の地区内でのみ移動がある場合の2つの仮説を考えた。年，月，場所，島と漁法，黒潮流路の接近，黒潮の型，水温の主効果と二次の交互作用を使用し，それぞれの地区について，年の主効果を含む全ての組合せのモデルを推定し AICの値を比較した。AIC が最小だったモデルは，最小二乗平均を使用し，他の効果を平均化して年変動を抽出した。1991年以降タカベの資源水準は横ばいであった。第五章は，年齢，漁獲量，CPUE の情報を使用し，移動に関する2つの仮説に基づき，資源量をチューニング VPA で推定した。第三章と飼育魚の知見より，耳石の方が鱗より真の年齢を当てる確率が高く，読み取り誤差が小さいことから，年別年齢別漁獲尾数を求める際，耳石の年齢が正しいと考え，鱗の年齢組成の偏りを耳石の基準に変換した。チューニングには，第四章で標準化した CPUE を使用し，最小二乗法でパラメータを推定した。さらに，CPUE の観測誤差と年齢査定誤差が，パラメータと資源量推定値に与える影響を評価した。1998年以降のタカベの資源量は600～700t 台を推移し，漁獲割合は2～3割だった。資源量推定値の誤差は，近年になると増大する傾向があり，2003年の変動係数は0.2程度だった。また，年齢別の選択率を調べた結果，高齢魚に対して若齢魚の漁獲圧が低いことが示された。これは，価格の高い大型魚を中心に漁獲するため，小型魚の漁獲が抑制されているものと考えられる。推定結果には，島間の移動の仮説による差がほとんどなく，資源管理方策の検討について同様の判断が可能と考えられる。%SPR は2003年の漁獲圧で約50％だった。YPR 解析の結果，漁獲圧を現状より高めた場合，全体の漁獲量はわずかに増加するものの，大型魚の漁獲量は減少することが示唆された。漁獲係数が F0.1に近いことや，年齢と漁獲の関係，YPR，SPR 解析の結果から判断すると，伊豆諸島北部海域のタカベ資源は漁獲過剰ではないと考えられる。タカベ資源の持続的利用のためには，現状の努力量水準と若齢魚に対する低い漁獲圧の両方を維持する必要がある。 | |||||||||||
| 言語 | ja | |||||||||||
| 書誌情報 |
ja : 水産総合研究センター研究報告 en : Bulletin of Fisheries Research Agency 巻 18, p. 167-242, ページ数 76, 発行日 2006-11 |
|||||||||||
| 出版者 | ||||||||||||
| 出版者 | 水産総合研究センター | |||||||||||
| 言語 | ja | |||||||||||
| ISSN | ||||||||||||
| 収録物識別子タイプ | PISSN | |||||||||||
| 収録物識別子 | 1346-9894 | |||||||||||
| 書誌レコードID | ||||||||||||
| 収録物識別子タイプ | NCID | |||||||||||
| 収録物識別子 | AA11589591 | |||||||||||
| 情報源 | ||||||||||||
| 識別子タイプ | Local | |||||||||||
| 関連識別子 | fra_k_18_167 | |||||||||||
| 関連サイト | ||||||||||||
| 識別子タイプ | URI | |||||||||||
| 関連識別子 | https://agriknowledge.affrc.go.jp/RN/2010740415 | |||||||||||
| 関連名称 | 日本農学文献記事索引（AgriKnowledge） | |||||||||||
| 著者版フラグ | ||||||||||||
| 出版タイプ | VoR | |||||||||||
| 出版タイプResource | http://purl.org/coar/version/c_970fb48d4fbd8a85 | |||||||||||
