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来源Some global fish stocks may be lower than thought: study
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2010年11月17日
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Some global fish stocks may be lower than thought: study
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学术争辩与共识:海洋鱼类储量比预计的还要低
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【译者注:本文的核心是两项研究的争辩——基于方法论差异的结论差异。个人以为,关注食物链顶端与关注食物链底端的研究方法在本质上是一致的,然而,后者的结论(而本文作者似乎是支持后者的)却有失偏颇——该项研究认为,食物链研究的目的在于,预测工业捕渔的后果,维护鱼类的可持续发展及海洋生态的健康平衡。而其结论是,在海洋生态“总量骤减”的前提下,工业捕渔是“促进”了海洋生态平衡的。首先,海洋生态“总量骤减”使得海洋生态系统未必健康,而人类捕渔是否加剧/加速了这种减少不得而知;其次,在骤减前提下,食物链底端的生态减少可能是由多种因素引起的——相对于食物链顶端的生态减少,其结论代表性反而有所降低。因此,后者对于前者的“指控”包含更多自以为是的“自相矛盾”。而两项研究的唯一共识即是本文标题——鱼类储量比预计的更低,而这一点就足以说明事实了。不过,值得一提的是,既然食物链顶端的海洋生物数量少,而且,科学研究的共识是,高级海洋生态一旦灭绝,海洋生态体系的全面减少则不可逆转,那么,究竟是“关注食物链顶端”的方法更具有操作性,更科学呢,还是关注食物链底端?在此基础之上,海洋生态的减少到底关不关人类的事儿?海洋生态的可持续发展到底关不关人类社会发展的事儿?】 a* d$ w; y4 v( a3 X
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A worker unloads a fresh catch of tuna for export to the US and Japan. A yardstick for estimating ocean fish stocks, many of which are under intensifying pressure from industrial trawling, is badly flawed, a study released Wednesday said.
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一名工人正在将一批新鲜的金枪鱼装箱——它们将被出口到美国和日本。星期三,一份研究成果指出,海洋鱼类存量的测量标准存在严重缺陷,因为,这些标准大都是在工业扩张的严酷压力下制定的,也即,工业发展使得存量被高估,而实际情况可能更糟糕。/ o9 A0 f/ q' W
1 M* N, @1 ?, Y0 q/ r: D As a result, global stocks of some commercially valuable top predators -- including certain species of tuna, sharks and halibut -- may be closer to collapse than thought, it warned.- j w- F2 Q* x' k2 B5 k4 ?: z
9 J- ~ H9 @3 H, D5 U, j因此,该项研究警告,那些极具商业价值、且处于食物链顶端的海产品——比如某些金枪鱼、鲨鱼或贝类品种——濒于消亡,而实际情况或许比预计的还要更糟糕。
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Since the late 1990s, scientists and regional management organisations have used catch data to measure changes in the balance of species across so-called "trophic levels."
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: g% l4 z- L4 V# c& ?$ _' D% h自1990年代起,科学家和区域性管理机构就已经开始了数据收集工作,以对所谓“热门领域”的生态平衡变化进行定量研究。0 Q( |8 B+ r. c' x z! Q. J
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The trophic level is the species' rank in the food chain. Microscopic sea algae have a trophic level of one, while large predators such as sharks or tuna are at the highest level, four." r7 s7 P8 v0 s$ }$ C6 k+ n
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“热门领域”测量法是在食物链中进行种群排名的一种实证方法。在宏观的“大海洋”体系中,由各种群中排名第一的特定类型的种群构成一个热门领域,而就处在食物链顶端(食肉性)的种群而言——如鲨鱼或金枪鱼——则选取排名前四的种群作为热门领域。; K+ A! h6 x+ ^# v
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Proportional changes within this ranking have been used as the indicator of how well a particular species is faring.
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因此,热门领域的种群比例变化被视作是特定种群发展差异的典型标志。
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If, for instance, a species of "Trophic Four" fish was in disproportionate decline compared with "Trophic Three" fish on which they feed, this would likely indicate overfishing.
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比如,就一个食肉类种群总体而言,最热门的四个鱼类品种之中有一类较之其他三类出现了“异动性”(与正常的生态平衡相比)减少,那么,这意味着,该类品种出现了过度捕食。 i( R r; {* e1 e z4 t/ o5 W
5 q, ~4 r7 @2 T2 l- M* H The method presumes that humans "fish down the food web" by over-harvesting fish at the highest levels and then sequentially going after fish further down the chain.$ @. G: b" V2 x& S
6 e! R8 G; l R7 h这种测量方法假设,人类是海洋生态体系中的“食肉类种群”,他们对海洋生态中“高级食肉种群”的过度捕获,导致海洋生态的食物链断裂,并使海洋生态的整体减少趋势不可逆转。(译者注:“热门研究法”假定,人类捕渔涉及海洋生态中的各类种群,研究者更倾向承认,人类对高级食肉种群进行过度捕获的结论,至于人类对低级海洋生物是否过度捕获,研究者不置可否。)1 e8 x0 u( r l
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But the new study says this technique is not smart enough.5 Z1 F3 A2 R' d2 n- S
) b8 h" }7 C1 W* G7 C8 ?但是,一项新研究却表明,这项热门领域的测量技术并不那么科学。; ?! S' [. G% b' n
' a; h, B: a q "Applied to individual ecosystems, it's like flipping a coin -- half the time you get the right answer and half the time you get the wrong answer," said Trevor Branch, a University of Washington professor.) _! z/ q0 d; A$ p8 Q) K
" }; J# E3 a4 z5 n1 d. }. i华盛顿大学的教授Trevor Branch指出,如果将(针对于海洋生态的)“热门领域”研究技术应用在人类生态系统中的话,那么,所谓的热门便不再是“热门”,就像抛硬币一样—— “热门”技术答对的次数和答错的次数接近平衡——硬币每面出现的比例各占50%。(译者注:前文中使用的是将人类总体或者是“渔人”置于海洋生态系统中的方法,而批评者则将海洋生态系统置于人类的工业化生态系统之中,并认为其不具有预测效果。笔者认为,批评者完全没有理解前文方法论的精妙之处。)
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"This is important, because that measure is the most widely adopted indicator by which to determine the health of marine ecosystems."
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就更成熟的生态系统而言,系统健康与否的衡量标准应当具有广泛的适用性,因此,“抛硬币”的结论是至关重要的,而前文所述的“热门领域”研究恰忽略了这一点。(译者注:批评者的言外之意似乎是,海洋生态的减少对人类社会的整体发展而言未必是坏事,至少是有利有弊的。)
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The method's shortcomings are illustrated by the case of the Gulf of Thailand, according to the paper, which appears in the journal Nature.1 j) G& z5 J2 s" w# H
c+ S1 D9 X6 j而自然之旅杂志上的一篇研究论文则以泰国Gulf的案例研究论证了基于“热门方法”研究在方法论上的不足。. x1 {9 i% d' Z7 g, V
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The average trophic level of what is being caught is rising -- and this in principle should indicate improving ecosystem health.! M; q7 l! I. l+ x
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热门鱼类的平均捕获率(而捕获正在并将持续进行)处于上升态势之中——按照所谓的热门领域理论,这应当意味着海洋生态系统的健康平衡发生了变化。
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But it turns out that fish at all levels have declined by about tenfold since the 1950s because of overharvesting.$ V: \8 f, V5 U. u- _. c
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但是,这一结果也证明了,人类的过度捕渔已经导致(各种)鱼类总体较之1950年减少了10倍左右。
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M' {, \4 t, G1 P This disastrous drop is masked because the "trophic level" system is based on looking at the top predators first, say the authors.5 z, J( p$ `" i4 p5 {
8 Z* Y( B- C+ e这项研究的作者批评道,“热门”理论系统首先关注上游食物链(食肉鱼类)的做法掩盖了海洋生态系统出现灾难性减少的整体性事实。9 T7 x: m+ t. S) i4 S2 Z* w
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But in the Gulf of Thailand, industry first targeted mussels and shrimps near the bottom of the food web before shifting to predators higher up, says the study.
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但是,在泰国的例子中,作者最先关注的是处于食物链底端的贝类和虾类,作为其他“海洋生物”的食物的比例。4 I, n8 P$ E7 c! x
1 L" _* N3 M9 G# H) A4 z When the researchers compared the catch-based method with a more accurate one, based on trawling over a long period of study, the results differed sharply in 13 out of the 29 ecosystems they evaluated.
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研究人员以这种关注食物链底端的视角对特定种群进行了聚焦性研究,并将其置于人类渔业全面工业化的大背景之中,结果发现,29个种群中的13个种群比例均出现了明显的减少。
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Applying both methods to worldwide data, the scientists say industrial fishing over the past decades has not simply worked its way downwards from the top of the food chain -- it has gone upwards, too.% i6 W5 v3 n) X3 Z& C
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如果将关注食物链顶端和底端的方法同时应用到全球性数据上,那么,科学家们得出的结论是,过去10年的工业捕渔不仅没有破坏海洋的生态平衡,反而促进了生态平衡。
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"Globally we're catching more of just about everything," Branch said.
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Branch认为,“全球化使我们收获的不仅仅是那些鱼。”
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5 g/ t( M' }, ]- S% n Relying on changes in the average trophic level of fish being caught "won't tell us when fishing is sustainable or if it is leading to collapse."
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上文提及的“热门鱼类捕获率的变化”模型不能够解释,人类捕渔究竟是促进了海洋生态的可持续发展还是导致了海洋生态体系的全面崩溃。. R- W. T8 _+ L. M
$ {& A- {& O9 q4 ^ Scientists not involved in the study said the findings could revolutionise the way fish populations are measured.
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. h+ Q8 i0 s# t) v+ B9 j4 m一些立场中立的科学家则指出,该项研究成果将使得海洋鱼类的量化方法发生革命性变革。
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9 S) e9 S% o1 A* D7 k$ K "This study makes clear that the most common indicator, average catch trophic level, is a woefully inadequate measure of the status of marine fisheries," said Henry Gholz, an environmental biologist at the US National Science Foundation.1 M* B# N, b4 U% K
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美国国家科学基金会的生物环境研究专家Henry Gholz指出,这项研究阐明了,在现代成熟渔业的背景下,以热门种群的平均捕获率代表海洋生态变动趋势的研究方法是不充分的。 |
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