2006/8/281 Effects of predator-prey interactions and adaptive change on sustainable yield Hiroyuki Matsuda Yokohama National University (Matsuda & Abrams 2004 Can J Fish Aq Sci 61: )

2006/8/282 Can we say goodbye to the MSY theory and a pessimistic view of the state of the world fisheries? FAO suggested that the total world landings do not increase any more. The Maximum Sustainable Yield theory always guarantees the stock persistence; The adaptive management is one of the best ways against uncertain ecosystems. I say the adaptive management sometimes results in undesired outcomes; I say the MSY theory does not guarantee coexistence of species = food web constraint; 4WFC organizer gave us the title of “getting more fish and reconciling fisheries with conservation”;

2006/8/283 Whales consume fish more than human (Tamura & Ohsumi 1997)

2006/8/284 Wasp-waist is a classic dream... Anyway, we need to investigate how to fluctuate the total biomass of small pelagics. birdssealstunas copepods krill...., is this illusion? pelagic sardine/anchovy lantern fish deep sea Only 5 to 10 percent of us succeed of the weight- loss industry

2006/8/285 What traits are frequency- dependent? Freq.-dep. selection may compensate overfishing; Freq.-indep. selction might accelerate extinctions Adaptation of any type of bet-hedging ??? age and size at maturetion reproductive effort growth rate morphology and behavior

2006/8/286 The age and size at maturity of a salmon Are recent smaller & older maturation phenotypic plasticity? K. Morita, S. Morita & H. Matsuda Can J Fish Aq Sce 年 5yr old 4yr old 3yr old 69 cm 3.7yr old 64 cm 4.2yr old Kaeriyama 1994 (mm)

2006/8/287 Rule for maturity Age-dep. Size dep maturation mixture Low growth High growth age Body length

2006/8/288 体長（ mm ） 50% 成熟体長平均成熟体長 3歳3歳 4歳4歳 5歳5歳 50% 成熟率 年齢 ・平均成熟体長は、 年齢とともに増加 ・ 50 ％成熟体長は、 年齢とともに低下 ・成長の悪い個体は、 高齢かつ小型で成 熟を開始する

2006/8/289

10 What age and season should we catch fish?

2006/8/2811 Constrained optimiation  =Y+  (P-N 0 ),  /  F(t)=0,  L(s)/  F(t)=-L (s>t) or 0 (s<t)

2006/8/2812 子供と産卵親魚は大切に マサバの 1980 年代の漁獲圧

2006/8/2813 Fisher(1930)Reprodutive value ある齢の魚を｢泳がせた｣ときに、将来 成長して次世代に貢献する期待産卵量  生存率 × 産卵数（体重）

2006/8/2814 Harvest value ある齢の魚を｢泳がせた｣ときに、 将来成長して漁獲に貢献する期待 漁獲量 –(Matsuda et al Env. Econ. Pol. St. 2: )  漁獲係数 × 生存率 × 魚価（体重）

2006/8/2815 ミナミマグロは回復するか？ Mori et al. Pop.Ecol 逆ベビーブーム現象

2006/8/2816 MSY (Maximum sustainable yield) theory dN/dt = r(1 – N/K)N – C If C<Kr 2 /4, two positive equilibria exist. Kr 2 /4 is MSY. MSY Over-fishing will lose future yield. Stock abundance N Production dN/dt

2006/8/2817 Requiem to Maximum Sustainable Yield Theory Ecosystems are uncertain, non- equilibrium and complex. MSY theory ignores all the three. Does MSY theory guarantee species persistence? - No!! Stock abundance surplus production

2006/8/2818 Effects of predator-prey interactions on sustainable yield Stock & yield Prey abundance

2006/8/2819 Stock & yield Fishing effort Y P The effort that achieves MSY can be close to the effort at which the stock collapses. Standard relationship between effort and yield Non-Standard relationship between effort and yield Non-Standard relationship between effort and yield Stock may increase in population size with increasing fishing effort 25min

2006/8/2820 Odd MSY curves (M & A 2004) Fishery may increase its resource abundance. “Classic” MSY

2006/8/2821 Prey-predator cycles decreases average predator abundance Prey abundance N Yield Stock P

2006/8/2822 Maximal yields from multi- species fisheries systems: rules for systems with multiple trophic levels. Matsuda & Abrams 2006 Ecol Appl 16:

2006/8/2823 Unconstrained MSY that maximizes the total yield from the community We choose fishing effort e i independently; 6-species systems including 2 prey random matrix with 50% probabilities; we seek r having a positive equilibrium; price p is 0-1 for prey, 0-10 for predators unconstrained MSY that may result in extinction; Constrained MSY that satisfies coexistence of all species

2006/8/ Some resultant biological communities at MSY (Matsuda & Abrams 2006) (b) (a) 12 5 (c) Solution maximizing total yield from community MSY solution often reduces species and links; (d) (e)

2006/8/ Examples of biological community at MSY (Matsuda & Abrams 2006) (b) (a) 12 5 (c) 100%92%61%12%6% …often exploit more species, more trophic levels (d) (e) Constrained MSY that guarantee coexistence

2006/8/2826 Result of (1) unconstrained and (2) constrained MSY ## extant species at (1) # exploited sp at (1) # exploited sp. at (2) ≧6≧ mean min

2006/8/2827 Conclusion (Matsuda & Abrams 2006 Ecol Appl) MSY theory does not guarantee species coexistence Fisheries must take care of biodiversity conservation explicitly

2006/8/2828 Management of small pelagics Kawai H, Yatsu A, Watanabe C, Mitani T, Katsukawa T, Matsuda H (2002) Recovery policy for chub mackerel stock using recruitment-per-spawning. Fish Sci 68: Matsuda H, Katsukawa T (2002) Fisheries Management Based on Ecosystem Dynamics and Feedback Control. Fish Oceanogr 11: Matsuda H, Kishida T, Kidachi, T (1992) Optimal harvesting policy for chub mackerel in Japan under a fluctuating environment. Can J Fish Aq Sci 49: Matsuda H, Wada T, Takeuchi Y, Matsumiya Y (1992) Model analysis of the effect of environmental fluctuation on the species replacement pattern of pelagic fishes under interspecific competition. Res Pop Ecol 34:

2006/8/2829 Species Replacement of Pelagic Fishes Catch in Japan (1000 mt) Anchovy Horse mackerels Pacific saury Chub mackerel Sardine

2006/8/2830 Target switching of multispecies fisheries (Katsukawa & Matsuda, Fish.Res. 2002) Policy 1 (no switching; NSF) Fishing effort E i = e i /3 (constant) Or E i = E i (x i ) (independent of x j ) Policy 2 (switching; SF) E i = e i x i /(  x i ) ( ∝ stock abundance) Fishers focus on relatively abundant fish species.

2006/8/2831 Switching increases & stabilizes total catch, save it at low levels Switching No Switching Switching If stock fluctuations of alternative fish are negatively correlated or independent

2006/8/2832 Cyclic Advantage Hypothesis based on ecosystem approach (species interaction) The next dominant to sardine is anchovy – Yes! As I predicted The second next is chub mackerel Many people agree now anchovy, Pacific saury, jack mackerel mackrel sardine Matsuda et al. (1992) Res. Pop. Ecol. 34:

2006/8/2833 Large fluctuation of recruitment in chub mackerel (Kuroshio stock) Strong year classes appeared twice

2006/8/2834 Immatures were heavily caught before the age at maturity 1970s1980s1990s1993- %immatures 65.0%60.0%87.0%90.6%

2006/8/2835 Future of Pelagic Fish Populations in the north-western Pacific: If overfishing of immatures continues, If cyclic replacement hypothesis is true, Do not catch immatures too much! –chub mackerel will not recover forever. –Fishers did not agree to my recommendation. –sardine will not recover forever either. –The overfishing is an experiment for my hypothesis. (adaptive mismanagement) –In 2003, fishers agreed to stock recovery plan!

2006/8/2836 Difficulties & hopelessness in ecosystem modeling We need many unverified assumptions and intuitive understanding is usually difficult “Ecosystem models without errors” often overfit observed data and predict a unique future. Indirect effects via the third species or adaptive change in traits is often counterintuitive and not negligible in the long-term effect (see Abrams, Polis…); Indeterminacy (Yodzis 1988): Results (+/-) vary with small change in parameter values

2006/8/2837 Catch of top predators may decrease its prey fish Time Population size Myth #3 Trophic cascade: decrease of predator always increases its prey.

2006/8/2838 Shiretoko World Nature Heritage (2005) We need evidence of sustainable fisheries in Shiretoko;

2006/8/2839 漁業 トド 植物プランクトン 動物プランクトン ホッケタラサケ科 ヒグマ カレイ類 海藻 さんま イワシ類 かに類 にしん さめ類 さば 二枚貝類 まぐろ あいなめ えび類 オキアミ類 髭クジラ類 イルカ類 栄養塩 デトリタス 多毛類 イカナゴ ぶり 巻貝 小型甲殻類 イカ類 タコ類 ソイ類 スケトウダラ 鰭脚類 死肉 海鷲類海鳥類 なまこ ウニ 赤字はキーストン種 桃地は非利用対象種 知床の海域生態系（部分図）

2006/8/2840 Fisheries Sealion phytoplankton zooplankton PleurogrammusCod Salmonids Bear Flatfishes seaweed Pacific saury Sardine & ancohvy crabs herring Sharks mackerel bibalves tunas Fat greenling shrimps krill Baleen whales Dolphins detritus lugworms Sand lance Yellowtail snails Crustacea squids octopi rockfish Walleye pollack Seals Dead body EaglesSeabirds Sea-cucamber Sea-urchins Keystone species Fisheries resources Draft Foodweb in Shiretoko World Heritage jellyfish