This draft was prepared in April 2001, modified, and last posted to the web on 20 August 2003 . Since the initial draft was prepared additional individuals have endorsed the contents and asked to be added to the list of "authors" - most of us are listed because we support the contents than because we helped with the writing, although the paper was the result of active discussion among a large group of scientists. We therefore provide a more current list of authors and endorsers who have asked to make known their support for the ideas expressed here.
Currently we are debating ways to make these counter-arguments more generally available. We invite ideas and contributions, and the result may be a series of papers with more reasonable numbers of authors, or perhaps a paper with a few principle authors and a list of endorsing scientists. If you are interested in joining this effort, please contact William Silvert who is coordinating the project at present.
A list of those who endorse the material is available here.
by
Eva Roth (1), Hans Ackefors (2), Frank Asche (3) Christian Balnath (4) Edward
Black (5), Kenneth Black (6), Andrew Boghen (7), Craig Browdy (8) Peter
Burbridge (9) John D. Castell (10), George Chamberlain (11), Konrad Dabrowski
(12), Ian Davies (13) Antoine Dosdat (14), Anastasio Eleftheriou,(15) Arne Ervik
(16), Hillel Gordin (17), Christopher S. Heinig (18), Volker Hilge (19), Ioannis
Karakassis (20) Holmer Kuhlmann (21), Thomas Landry (22), Mathias von Lukowicz
(23), Jaqueline McGlade (24), Andrew Price (25), Robertt B. Rheault (26), Harald
Rosenthal (27), Ulrich Saint-Paul (28), Paul A. Sandifer (29) Marco Saroglia
(30), William Silvert (31), Werner Steffens (32), Doris Soto (33), Laszlo Varadi
(34), Johan Verreth (35), Marc Verdegem (36), Uwe Waller (37)
(1) Institute of Environmental and Business Economics, University of Southern
Denmark, Denmark
(2) Department of Zoology, Stockholm University, Sweden
(3) School of Science and Technology, Stavanger University College,
Stavanger, Norway
(4) Institute for Marine Science, University of Kiel, Kiel, Germany
(5) Comox, British Columbia, Canada
(6) Dunstaffnage Marine Laboratory, Oban, Argyll, Scotland, UK
(7) Département de biologie, Université de Moncton, NB, Canada
(8) Marine Resources Research Institute, South Carolina Department of Natural
Resources, Charleston, USA
(9) Department of Marine Sciences and Coastal Management, University of
Newcastle upon Tyne,UK
(10) Department of Fisheries and Oceans, Biological Station St. Andrews, NB,
Canada
(11) Global Aquaculture Alliance, St. Louis, MO, USA
(12) School of Natural Resources, Ohio State University, Columbus, Ohio, USA
(13) FisheriesResearch Services, Marine Laboratory, Aberdeen,UK
(14) A.D. Station Experimentale d’Aquaculture, IFREMER, Palavas les Flots,
France
(15) Institute of Marine Biology of Crete, Iraklion, Crete, Greece
(16) Institute of Marine Research, Bergen, Norway
(17) Mariculture Div., Dep. Fisheries & Aquaculture, Ministry of
Agricult. & Rural Develop., Israel
(19) Federal Research Board of Fisheries, Institute of Fishery Ecology,
Ahrensburg, Germany
(20) Institute of Marine Biology of Crete, Heraklion, Crete, Greece
(21) Federal Research Board of Fisheries, Institute of Fishery Ecology,
Ahrensburg, Germany
(22) Science Branch, Gulf Fisheries Centre, Moncton, Canada
(23) Bavarian State Institute for Fisheries, Germany
(24) London University College, England
(25) Ecology and Epidemology Group, Department of Biological Sciences,
University of Warwick, UK
(26) Moonstone Oysters, 1121 Mooresfield Rd., Wakefield, RI 02879, USA
(27) Institute for Marine Science, University of Kiel, Kiel, Germany
(28) Center for Tropical Marine Ecology, Bremen, Germany
(29) South Carolina Department of Natural Resources, Columbia, South
Carolina, USA
(30) Department of Structural and Functional Biology, University of Insubria,
Varese, Italy
(31) Portuguese Institute for Fisheries
and Sea Research, Lisbon, Portugal
(32) Deutscher-Fisherei-Verband, Hamburg, Germany
(33) Faculty of Fisheries and Oceanography, University of South Chile, Puerto
Montt, Chile
(34) Fish Culture Research Institute, Szarvas, Hungary
(35) Fish Culture and Fisheries Group, Wageningen Institute of Animal
Sciences, Wageningen University, The Netherlands
(36) Fish Culture and Fisheries Group, Wageningen Institute of Animal
Sciences, Wageningen University, The Netherlands
(37) Institute for Marine Science, University of Kiel, Kiel, Germany
The publication cited above (Naylor et al., 2000) was interpreted by "NATURE" on its cover page as the "Downside of Aquaculture". We agree with the overall objective of the authors to develop sustainable aquaculture management practices. Unfortunately the paper contains numerous flaws and misconceptions as well as inaccurate reporting of facts. These shortcomings cannot be fully addressed within this response statement. We therefore focus our comments on a few key issues from the paper:
The main issue raised by Naylor et al. (2000) is that while aquaculture provides a partial solution to the collapse of commercial fisheries stocks world-wide, it also contributes to that collapse. The authors argue that, because of the need for fishmeal and fish oil for pelleted fish diets, the growth in farmed fish harvests from 10 to 29 Mt over the past decade helps to explain current patterns of oceanic fish capture. We counter this argument from three viewpoints.
First, the major increase in aquaculture production originates from herbivorous and not from carnivorous species (Fig1) and, therefore, this development is to date independent of the worldwide capture of wild fish. The greatest increases in production are found in developing countries (FAO, 2000), such as China, where fish farming is building on traditional practices that have been in existence for centuries (Zhiwen, 1999), mainly using carps and other omnivorous species and therefore have seen an increase in production of species thriving at lower trophic levels. Among the remaining portion of cultured fish species in Asia and other parts of the world are carnivorous once which are at present partially in need of fishmeal as a protein source.
Second, the balance between carnivorous and non-carnivorous species in aquaculture production is heavily skewed towards the latter (Fig.1). Farming of non-carnivorous species does not rely heavily on fishmeal-based feeds (perhaps 10-15% if it is used at all for some of the more omnivorous species (Tacon, 2000)). Therefore, the argument that aquaculture based on carnivorous species is driving up the capture of small pelagics is difficult to support. This argument would imply that the demand for dietary protein by aquaculture would increase the world market price for fishmeal. Fish meal constitutes only 4% of the total oil meal market demand (Asche and Tveterås, 2000), and estimates of the share of fish meal for use in aquaculture varies between 17- 20% (Pike, 1999; Gérin, 1999) and 35% (Chamberlain and Barlow, 2000). Hence, terrestrial live stock production is the most influential factor with respect to the demand for fishmeal. This, together with the fluctuation in fish stock sizes caused, for example, by the environmental effects of El Niño, largely determines the changes in market price for fishmeal as depicted in Figure 2. From this figure it can also be deduced from the price structure, that available substitutes (e.g. Soya meal) follows the same pattern, indicating that Soya is a close substitute for fishmeal. With this market structure, increased demand for fishmeal from aquaculture cannot have any significant effect on fishmeal prices, and it does not follow that it will lead to increase fishing pressure (Asche and Tveterås, 2000).
Other market and environmental scenarios may place severe pressures on the fish meal market and by far outweigh the importance of aquaculture as a factor in increased fishing pressures as contended by Naylor et al (2000). For example, to limit the spread of the bovine spongiform encephalopathy, BSE, the European Commission recently installed a total ban on the use of warm-blooded animal meals in feeds for livestock animals. In this ban fish meal and fish oil were not included. As a consequence, the demand for fish meal as a substitute for meat and bone meal in livestock diets may increase strongly.
A much more important issue than using fish meal for feeding aquaculture species high or low in the food chain is the fact that many of the fish meal/fish oil resources today are contaminated by substances such as dioxins to the extent that they can no longer be used for any food production for human consumption (Lundebye et al. 2000; European Commission, Scientific Committee on Animal Nutrition, 2000a,b) unless costly clean-up procedures are effectively developed and employed. This was totally neglected by Naylor et al (2000). This automatically implies that fish meal and fish oil originating from areas with dioxin pollution will face higher production costs and this will limit their use.
Carnivorous fish culture in the future will not necessarily have to use fish meal as protein source. Moreover, less fish meal is used for each kilo of farmed fish produced because of improved feed conversion efficiency (Asche et al, 1999) and protein and energy conversion is in general higher in fish than in warm-blooded terrestrial animals (Steffens, 1989; Åsgård and Austreng, 1995) Additionally, there is ample evidence that carnivorous fish can utilize plant proteins in their diets more efficiently than do omnivorous fish species. Diet formulations for salmonides can in principle be made completely fish meal free without a detrimental effect on growth and with significantly reduced waste outputs (Kaushik et al, 1995; Dabrowski et al. 2000), however, to date it is unclear whether this is desirable. In any event, such shift in protein resource use in carnivorous fish culture would mean to change their "trophic value" in relation to perceived ecological consequences (e.g. "farming up the food web").
Thirdly, Naylor et al (2000) conclude that culture of non-carnivorous species has a lower ecological impact. This is not necessarily the case. The culture of non-carnivorous species can also have an ecologically damaging effect if not managed properly, depending on the scale and type of operation. For example, it is now recognized that conventional pond farming of fish and inappropriate combinations of species in modern integrated farming systems (e.g. fish, pigs, and chicken) in Asia can foster human disease vectors which may subsequently affect human health (e.g. influenza pandemic) (Din et al., 1988).
The argument is not which species are cultured, but rather which species combination are used, as well as the degree to which production processes are suited to prevailing environmental conditions. Shrimp culture, for example, has caused significant problems in some areas (Primavera 1977, DeGraaf and Xuan, 1998; Paez-Osuna et al., 1998; Thanh et al. 1999; FAO, 1999) where it has been allowed to operate in an uncontrolled manner (Boyd and Masset, 1997). However, experts agree that shrimp and fish farming can be practiced in an environmentally friendly manner (Hopkins et al, 1995; Sandifer et al., 1996; Macintosh, 1998; Karakassis et al, 2000). These best practices should be promoted (Boyd, 1999). National laws in shrimp producing countries now prohibit mangrove alienation. Mangrove conservation and mangrove exploitation is being integrated into farm management practices (Lassen, 1997). Past errors in modern finfish farming which have led to environmental deterioration have also been documented. However, environmental concerns expressed by aquaculturists and scientists have led to substantial improvements in aquaculture systems in past years (ICES, 1995, 1999). For a number of aquaculture systems, integrated culture involving species of various trophic levels could greatly enhance production while minimizing environmental costs and converting wastes into useful products (Soto and Mena, 1999; Shpigel et al, 1993; Neori et al 1996,1998). One major constraint in enforcing good practice is the probity of administrations and their determination to support best practice in the face of competing pressures, an important issue often neglected.
Given that there is an increasing demand for freshwater resources and space
in the coastal zone, it is critical that there should now be a balanced debate
about the extent of aquaculture as well as the volume and type of species to be
produced. Some arguments presented by Naylor et al. (2000) derive from rhetoric
rather than fact and do little to help the real debate about how we should
address food security in tandem with environmental protection.
References
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Asche, F., Guttormsen, A.G., Tveterås, R. 1999. Environmental problems, productivity and innovations in Norwegian Salmon Aquaculture. Aquaculture Economics and Management 3: 19-30.
Åsgård T. & Austreng, E. 1995. Optimal utilization of marine protein and lipids for human interests. Pp 79-87. In: Reinertsen, E, Haaland, H. (eds):"Sustainable Fish Farming, Proc. 1st intern. Symp. On sustainable fish farming." Oslo, Norway
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Figure 1 Trends in Chinese carp production (species low in the food chain) over the past 20 years (after Zhiwen, 1999) in comparison with the 1999 salmon production level in Norway (data from various sources). It should be noted, that the Zhiwen (1999) data might be an overestimate. (Rosenthal, personal communication).
Figure 2. Fluctuations of monthly fishmeal and soybean meal prices (US$ per tonne) at three different markets during the period of January 1981 and April 1999 (after Asche and Tveterås, 2000)
