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  • 1
    Publication Date: 2010-11-19
    Description: Biodiversity indicators provide a vital window on the state of the planet, guiding policy development and management. The most widely adopted marine indicator is mean trophic level (MTL) from catches, intended to detect shifts from high-trophic-level predators to low-trophic-level invertebrates and plankton-feeders. This indicator underpins reported trends in human impacts, declining when predators collapse ("fishing down marine food webs") and when low-trophic-level fisheries expand ("fishing through marine food webs"). The assumption is that catch MTL measures changes in ecosystem MTL and biodiversity. Here we combine model predictions with global assessments of MTL from catches, trawl surveys and fisheries stock assessments and find that catch MTL does not reliably predict changes in marine ecosystems. Instead, catch MTL trends often diverge from ecosystem MTL trends obtained from surveys and assessments. In contrast to previous findings of rapid declines in catch MTL, we observe recent increases in catch, survey and assessment MTL. However, catches from most trophic levels are rising, which can intensify fishery collapses even when MTL trends are stable or increasing. To detect fishing impacts on marine biodiversity, we recommend greater efforts to measure true abundance trends for marine species, especially those most vulnerable to fishing.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Branch, Trevor A -- Watson, Reg -- Fulton, Elizabeth A -- Jennings, Simon -- McGilliard, Carey R -- Pablico, Grace T -- Ricard, Daniel -- Tracey, Sean R -- England -- Nature. 2010 Nov 18;468(7322):431-5. doi: 10.1038/nature09528.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉School of Aquatic and Fishery Sciences, Box 355020, University of Washington, Seattle, Washington 98195-5020, USA. tbranch@uw.edu〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/21085178" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Aquatic Organisms/*isolation & purification/*metabolism ; Biodiversity ; Biomass ; Databases, Factual ; *Ecosystem ; Environmental Policy ; *Fisheries ; *Fishes/metabolism ; Food Chain ; Human Activities ; Invertebrates/metabolism ; Models, Biological ; Plankton/metabolism
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
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  • 2
    Publication Date: 2009-08-01
    Description: After a long history of overexploitation, increasing efforts to restore marine ecosystems and rebuild fisheries are under way. Here, we analyze current trends from a fisheries and conservation perspective. In 5 of 10 well-studied ecosystems, the average exploitation rate has recently declined and is now at or below the rate predicted to achieve maximum sustainable yield for seven systems. Yet 63% of assessed fish stocks worldwide still require rebuilding, and even lower exploitation rates are needed to reverse the collapse of vulnerable species. Combined fisheries and conservation objectives can be achieved by merging diverse management actions, including catch restrictions, gear modification, and closed areas, depending on local context. Impacts of international fleets and the lack of alternatives to fishing complicate prospects for rebuilding fisheries in many poorer regions, highlighting the need for a global perspective on rebuilding marine resources.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Worm, Boris -- Hilborn, Ray -- Baum, Julia K -- Branch, Trevor A -- Collie, Jeremy S -- Costello, Christopher -- Fogarty, Michael J -- Fulton, Elizabeth A -- Hutchings, Jeffrey A -- Jennings, Simon -- Jensen, Olaf P -- Lotze, Heike K -- Mace, Pamela M -- McClanahan, Tim R -- Minto, Coilin -- Palumbi, Stephen R -- Parma, Ana M -- Ricard, Daniel -- Rosenberg, Andrew A -- Watson, Reg -- Zeller, Dirk -- New York, N.Y. -- Science. 2009 Jul 31;325(5940):578-85. doi: 10.1126/science.1173146.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Biology Department, Dalhousie University, Halifax, NS B3H 4J1, Canada. bworm@dal.ca〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/19644114" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Biodiversity ; Biomass ; *Conservation of Natural Resources ; *Ecosystem ; *Fisheries/methods ; *Fishes/anatomy & histology ; Internationality ; Marine Biology ; Models, Biological ; Oceans and Seas ; Population Dynamics
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 3
    Publication Date: 2013-03-30
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Branch, Trevor A -- Hively, Daniel J -- Hilborn, Ray -- England -- Nature. 2013 Mar 28;495(7442):E5-6; discussion E7. doi: 10.1038/nature11974.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉School of Aquatic & Fishery Sciences, Box 355020, University of Washington, Seattle, Washington 98195, USA. tbranch@uw.edu〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/23538835" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Conservation of Natural Resources/*statistics & numerical data ; *Ecosystem ; Environmental Monitoring/*methods ; *Internationality ; Marine Biology/*methods ; Oceanography/*methods ; *Seawater
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
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  • 4
    Publication Date: 2013-02-22
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Pauly, Daniel -- Hilborn, Ray -- Branch, Trevor A -- England -- Nature. 2013 Feb 21;494(7437):303-6. doi: 10.1038/494303a.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Fisheries Centre of the University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada. d.pauly@fisheries.ubc.ca〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/23426308" target="_blank"〉PubMed〈/a〉
    Keywords: Age Distribution ; Animals ; Body Size ; Conservation of Natural Resources/*methods/*statistics & numerical data ; Ecology/*methods ; *Ecosystem ; Fisheries/methods/*statistics & numerical data ; Fishes/*physiology ; Population Dynamics ; Reproducibility of Results ; Uncertainty
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
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  • 5
    Publication Date: 2010-06-21
    Print ISSN: 0027-8424
    Electronic ISSN: 1091-6490
    Topics: Biology , Medicine , Natural Sciences in General
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  • 6
    Publication Date: 2012-08-22
    Description: Anderson, S. C., Branch, T. A., Ricard, D., and Lotze, H. K. 2012. Assessing global marine fishery status with a revised dynamic catch-based method and stock-assessment reference points. – ICES Journal of Marine Science, 69: . The assessment of fishery status is essential for management, yet fishery-independent estimates of abundance are lacking for most fisheries. Methods exist to infer fishery status from catches, but the most commonly used method is biased towards classifying fisheries as overexploited or collapsed through time and does not account for still-developing fisheries. We introduce a revised method that overcomes these deficiencies by smoothing catch series iteratively, declaring fisheries developing within three years of peak catch, and calibrating thresholds to biological reference points. Compared with status obtained from stock-assessment reference points for 210 stocks, our approach provides a more realistic assessment than the original method, but cannot be perfect because catches are influenced by factors other than biomass. Applied to FAO catches, our method suggests in 2006 32% of global fisheries were developing, 27% fully exploited, 25% overexploited, and 16% collapsed or closed. Although less dire than previous assessments, this still indicates substantial numbers of overexploited stocks. Probably because median exploitation rate decreased since 1992, our catch-based results do not reflect recent stabilization of assessed-stock biomass. Whether this outlook also applies to unassessed stocks can only be revealed with increased or more representative collection of biomass- and exploitation-rate trends.
    Print ISSN: 1054-3139
    Electronic ISSN: 1095-9289
    Topics: Biology , Geosciences , Physics
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  • 7
    Publication Date: 2014-10-04
    Description: Previous meta-analysis of spawner–recruit relationships suggested that depensatory behaviour is uncommon, and stocks pushed to low abundance are unlikely to suffer decreases in recruitment more severe than would be expected based on the decline in spawning stock. Using an updated database that has over 100 stocks that were depleted to less than 20% of their maximum observed stock size, we tested for depensatory behaviour in both total surplus production and recruitment and we also examined the probability of stock increase as a function of stock size and fishing pressure. The number of stocks that showed a significant improvement with depensatory models was less than that expected by chance. Hierarchical meta-analysis showed that the majority of the evidence was for no depensatory behaviour but could not rule out depensation at very low stock sizes. Stocks that are depleted to low abundance are expected to rebuild when fishing pressure is reduced if the environment has not changed but there is considerable evidence that the majority of fish stocks are impacted by changes in productivity regimes. Nevertheless, if stocks are very heavily depleted and fishing pressure is not reduced to quite low levels, the expected recovery time is both uncertain and long. Very low abundance should clearly be avoided for many reasons and the range of abundance where depensation cannot be ruled out is well below commonly adopted limit reference points.
    Print ISSN: 1054-3139
    Electronic ISSN: 1095-9289
    Topics: Biology , Geosciences , Physics
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