トウゴウ シゲン ヒョウカ モデル ニ モチイル タイチョウ ソセイ データ ノ オモミヅケ ショキチ ヒョウカ

統合モデルを用いた資源解析における最重要課題の一つとして，各尤度コンポーネント（資源量指数，サイズ組成データ等）の重みづけが解析結果に直接的に影響することが挙げられる。2012年に行われた太平洋クロマグロの資源評価では，この課題に対処するべく慎重な議論が交わされたが，主要な漁業である日本海まき網のサイズ組成データと他漁業の資源量指数の間で尤度コンポーネントの最適値に矛盾が生じ，妥当な解決策には至らなかった。そこで本研究では体長組成データの妥当な重みづけ初期値を決定する手法について，有効サンプル数とその信頼範囲を用いて決定する方法のパフォーマンスを検討した。初めに，体長組成データそのものの精度を評価するため，クラスターサンプリングを考慮した有効サンプル数を推定した。次に，最適な重みづけ手法を探るためシミュレーションを行い，各手法における尤度への影響を調べた。その結果，本研究の手法により日本海のまき網漁業のサイズ組成データと他漁業の資源量指数間に見られる矛盾は軽減され，尤度も改善された一方で，過去の資源評価と本研究における親魚量推定値の差は大きくはないことが明らかになった。しかし，世界的に注目が集まる本種の場合，僅かな差であっても資源管理に大きな影響を及ぼすと考えられる。また，重みづけ値をどのように決定するかという問題はあらゆる魚種の資源評価に共通するものであり，様々な漁業におけるデータの重みづけ初期値について考察する。In stock analysis using integrated age-structured models, weighting factors of each likelihood component (e.g., for abundance indices and size composition data) directly affect the estimation of the model. In a past stock assessment of Pacific bluefin tuna (PBF) conducted in 2012, conflicts were recognized between the length composition dataset of a purse seine fishery operating in the Sea of Japan (PS-SoJ) and the abundance indices derived from other fisheries. After careful consideration, the initial weighting factor used in iterative reweighting method for the length composition dataset of PS-SoJ was reduced. In this paper, we provide a further analysis of procedure for determining the initial weighting factor of the likelihood component for the length composition dataset of PS-SoJ used in the stock assessment model of PBF. We tested five scenarios involving alternative initial weighting factors. Firstly, we estimated an effective sample size as an initial weighting factor considering inherent accuracy and precision of the length composition dataset in the context of cluster sampling. Next, we illustrated the partial likelihood of estimated key parameter (i.e. R0) as indicator of model fit for the tested scenarios to suggest optimal methods. In the results, the model fit was improved in a scenario where the point estimate of the effective sample size except for highly uncertain years was used. The differences between the statistical point estimates of stock dynamics in each scenario would have significant effect on management considering PBF’s situation. In conclusion, we discussed appropriate methods of setting initial weighting factors for a variety of data conditions

Notes on an exhausted Japanese common squid, Todarodes pacificus (Cephalopoda: Ommastrephidae), with an unusually short arm

A Japanese common squid, Todarodes pacificus with an unusually short left fourth arm was captured from the Sea of Japan on October 1996. This specimen was a mature male (mantle length 216 mm, body weight 186 g) "Kawa-ika" squid that seemed to be nearing the end of its reproductive life. About two-thirds of the left fourth arm of this individual was lost and the surface of the arm's tip was completely covered with skin. This short arm was either caused by i) malformation or ii) accidental loss of the tip, followed by regeneration. Arm regeneration is common in cephalopods, and the left fourth arm of the present specimen was very similar to the regenerating arms of other cephalopods. Therefore, the arm of the present specimen may be regenerating. Since T. pacificus is a terminal spawner, this specimen indicates that regeneration can still occur even during later phases of the life cycle

Transition-Metal-Free Reductive Coupling of 1,3-Butadienes with Aldehydes Catalyzed by Dibutyliodotin Hydride

In this study, the Bu₂SnIH-catalyzed direct coupling of 1,3-dienes with aldehydes was developed. This reaction could be suitable for coupling without the use of transition-metal catalysts. Many types of aldehydes were applied to this reaction. The addition of MeOH promoted the catalytic cycle