http://risk.kan.ynu.ac.jp/matsuda/2005/050330Osaka.ppt 順応的管理が破壊する多種共存状態 Adaptive management may destroy coexistence. 松田裕之（横浜国大・環境情報） Hiroyuki MATSUDA (Yokohama Nat’l Univ) 2003/12/12 1 “...in a complicated food web structure, indirect effects of culling top predator (whales)ideaon Two phenotypes of whales-fisheries competition abundance of target fish is either positive or negative,...” By Yodzis 2001 Trend Ecol Evol Whales destroy the ocean. Fisheries destroy the ocean. By Japan Gov. 2003/12/12 2 What is one of the most important knowledge in community ecology? • Indeterminacy in indirect effects of community interactions (Yodzis 1988); • From sensitivity analysis, the total effect between species is positive or negative even though process errors exist in growth rate; • The “vulnerability” is not common for all species, and changes with conditions (evolutionary ecology). 2003/12/12 6 5 4 3 1 2 3 is this dream... illusion? Wasp-waist is a, classic birds seals sardine/anchovy pelagic tunas lantern fish deep sea Only 5 to 10 percent of us copepods krill .... succeed of the weightloss industry • Anyway, we need to investigate how to fluctuate the total biomass of small pelagics. 2003/12/12 4 （海洋）生態系モデル • Ecosim with Ecopath (Christensen et al. 1997) • Fishbase – 食性データ – 生活史データ • 資源量評価 • 非漁獲対象種の知見 2003/12/12 5 捕鯨 = 0，vulnerability= 0.3のときの三陸沖エコ シムの結果（Okamura2003) サＥ バＣ がＯ 減Ｓ Ｉ りＭ 続に けよ るる 。数 （ 岡値 村計 二算 〇。 〇 三 ） 2003/12/12 6 捕鯨 = 0，vulnerability= 0.6のときの三陸沖エコ シムの結果（Okamura2003) サＥ バＣ がＯ 減Ｓ Ｉ りＭ 続に けよ るる 。数 （ 岡値 村計 二算 〇。 〇 三 ） 2003/12/12 7 漁業 = 0，vulnerability= 0.3のときの三陸沖エコ シムの結果（Okamura2003) 鯨Ｅ がＣ 減Ｏ Ｓ りＩ 続Ｍ けに るよ 。る （ 岡数 村値 二計 〇算 〇。 三 ） 2003/12/12 8 捕鯨 =×2，vulnerability= 0.3のときの三陸沖エ コシムの結果（Okamura2003) サＥ バＣ がＯ 増Ｓ Ｉ えＭ るに 。よ （ 岡る 村数 二値 〇計 〇算 三。 ） 2003/12/12 9 鯨類の摂食量と漁獲量 2003/12/12 10 鯨類の初期資源量と現在 2003/12/12 11 謬説：クジラ害獣論 Fallacy of whale-fishery competition as reason for culling whales • 鯨はカタクチイワシ、中深層性ハダカイワシなどを大量に 摂食 • 必ずしも漁業とは競合しない • 大昔より鯨類全体としては減っている • たくさんいるミンク鯨 を食べよう！ 資料：日本鯨類研究所 2003/12/12 file: Institute for Cetacean Research 12 Whales Before Whaling in the North Atlantic Roman J & • DNA多様性解析： 大西洋の鯨類は商 業捕鯨以前より ずっと少ない（差 ＞累積捕獲数） Population abundance (thousands) Palumbi SR (2003) Science 301:508-510 Historical Current 600 300 Humpback 2003/12/12 Fin Minke 13 大型魚類の生物体量97-99%減少説 (Jennings & Blanchard 2004 J Anim Ecol 73:632) • • “We propose a method, based on macroecological theory, to predict the abundance and size-structure of an unexploited fish community from a theoretical abundance–body mass relationship (size spectrum). “We suggest that the current biomass of large fishes weighing 4–16 kg and 16–66 kg, respectively, is 97·4% and 99·2% lower than in the absence of fisheries exploitation. The results suggest that depletion of large fishes due to fisheries exploitation exceeds that described in many short-term studies. 2003/12/12 14 マグロ世界漁獲量は増え続けている 1960-90年の漁獲で9割減少 減ったマグロを取り続けている 2003/12/12 15 最大持続生産量理論の幻想 Fallacy of MSY theory • Ecosystem is fluctuating, uncertain & complex – MSY theory ignores all of these 3 factors • fluctuation→adaptive management, public involvement • uncertainty→risk management & communication • complex→ecosystem-based management 資源回復確率 2003/12/12 70-80 年代の漁獲圧なら 90 年代の未成魚乱獲 を続けると 16 Theory of sustainable fisheries • • • • Fishery is an origin of sustainability. Fish is a renewable resource. Overexploitation will lose both conservation and future yield. Do sustainable fisheries guarantee conservation? No! 最大持続生産量 MSY(Maximum sustainable yield) 2003/12/12 MSY 17 ２つの食物網 被食者－捕食者系 Prey-predator system 多種系 multi-species system 9 10 P 8 7 N 5 6 1 2003/12/12 4 2 3 18 Harvest of prey (Matsuda & Abrams in review) dN r(1 N ) N fN P qEN dt K 1 hN dP d P bfN P 1 hN dt Catch of prey will decrease predator, rather than prey dP/dt=0 dN/dt=0 In the case of feedback control, dE U (N S ) dt 2003/12/12 19 Feedback control in fishing effort is powerful... dE U N N * dt dN f ( N ) qEN dt N*N* f(N) A straw man says; • Even though the MSY level is unknown, the feedback control stabilizes a broad range of target stock level. N* Stock size N 2003/12/12 20 If fishing effort is regulated by stock abundance, (Matsuda & Abrams unpublished) dN r(1 N ) N fN P qEN dt K 1 hN bfN dP d gP P 1 hN dt dE/dt = u(N-NT) 2003/12/12 21 フィードバック管理は捕食者駆逐，漁業 (d)(e) (f) 崩壊、不規則変動，長期禁漁をもたらす Prey Fishing effort Predator • Feedback control may result in extinction of either fishery or predator. 2003/12/12 (a) (b) (c) 22 Feedback control with community interactions also result in undesired outcomes. (M & A unpublished) dNi ri a ji N j qei Ni dt j 9 10 8 r = (0.454,1.059,1.186,0.247,-0.006,-0.028,-0.059,-0.704,-0.308,-0.238) 7 A = (aji) = 1. 0.74 0.19 0.31 0. 0. 0. 0. 0.7 0.46 0.74 1. 0.87 0.08 0.46 0.66 0.48 0.73 0.84 0. 0.19 0.87 1. 0.96 0.08 0.14 0.83 0. 0. 0.68 2003/12/12 0.31 0.08 0.96 1. 0. 0. 0. 0.28 0. 0.88 0. 0.46 0.08 0. 0.1 0. 0. 0.92 0.15 0.84 0. 0.66 0.14 0. 0. 0.1 0.01 0. 0.5 0.69 0. 0.48 0.83 0. 0. 0.01 0.1 0.56 0. 0. e9 = 0.1, ei = 0 0. 0.73 0. 0.28 0.92 0. 0.56 0.1 0.28 0. 0.7 0.84 0. 0. 0.15 0.5 0. 0.28 0.1 0. 0.46 0. 0.68 0.88 0.84 0.69 0. 0. 0. 0.1 5 6 1 4 2 3 23 Feedback control may result in extinction of other species (sp. 6). ratio de9/dt = u(N9-N9*) 2003/12/12 24 Notice on feedback control • Single stock monitoring is dangerous • Target stock level is much more sensitive than we have considered in single stock models. • We must monitor not only stock level of target species, but also species that interacts with the target species. 2003/12/12 25 Total Allowable Catch rule 乱獲 BF=0 PP 2003/12/12 26 If fishing effort is a function of stock abundance, • １種系 2003/12/12 27 ２種系 Prey Predator 2003/12/12 28
© Copyright 2024 ExpyDoc
