By Claude E. Boyd1, Aaron A. McNevin2
A strong case for the paramount importance of FCR as an indicator of resource use and water quality impacts of feed-based aquaculture has been made (Boyd et al. 2007, 2015). By reducing FCR, there is a corresponding reduction in nutrient input, waste load, direct impacts of feed manufacturing, embodied resources and impacts for feed ingredient production, and production cost per unit of production (Boyd and McNevin 2015b). Certification programs consider FCR – either by specifying a maximum value or requiring it to be reported.
Nevertheless, limitations on pH and concentrations or loads of nutrients, turbidity or suspended matter, and biological oxygen demand are common standards in certification. The fact that concentration limits are imposed may have value in preventing adverse condition in the mixing zone (the immediate area where effluents enter the receiving water body), but they do not assure that the receiving water body will not be polluted, because the waste load may exceed the assimilative capacity of these water bodies.
In some instances, shrimp farms may be located in the same area that receives wastewater discharge from a large city and drainage from agricultural areas. In such instances, certification of all the shrimp farms in the downstream area might not result in significant improvement in water quality. In the case of the shrimp farms depicted, certification of a few shrimp farms would not cause a significant decline in pollution load from the entire shrimp production in the area. There are situations where the major source of pollution to a water body is one or more certified shrimp farms. Nevertheless, compliance with the standards will not assure that eutrophication does not occur in the receiving waters. The assimilation capacity of the receiving water bodies will not be known, and therefore, an estimate of permissible waste loads cannot be made. Determination of the assimilative capacity of receiving water bodies is far too complex to serve as a requirement for certification.
Analyses of effluent samples for demonstrating compliance with standards usually is done by an independent, certified laboratory, but in some cases, the farm is allowed to make the analyses. Particular methods of analyses (or their equivalents) usually are specified. Recent investigations showed that different laboratories – including certified laboratories – may provide remarkably different results although using the same method for the same water sample (Le and Boyd 2013; Somridhivej and Boyd, in preparation). Moreover, different methods may provide different results for the same sample (Zhou and Boyd 2015), and several methods are available for analyzing most variables. Usually no clear indication is given as to which methods are equivalent to the method specified by the certification program. In summary, there is presently no effective quality control for the analyses of farm effluents necessary to show compliance with certification standards.
The uncertainty with the benefits that can be realized by compliance with the standards and the likelihood of compliance being awarded based on erroneous analytical results, supports the Aquaculture Stewardship Council certification requirement to measure the diel fluctuation in dissolved oxygen concentration to ascertain the trophic status of the receiving water body before initial certification and to assess whether trophic status improves or declines later. This approach, especially if coupled with a FCR standard well below the typical FCR achieved for the culture species, would appear to be superior and less complicated than reliance upon effluent limitations for concentrations, loads, or both.
The measurement of diel dissolved oxygen fluctuation also might be considered as a standard for excluding certified farms from certain areas. It would seem logical to exclude certified farms from discharging into oligotrophic water bodies with little fluctuation in diel dissolved oxygen concentration and from highly eutrophic water bodies with especially wide ranges in diel dissolved oxygen concentration. The logic for exclusion from oligotrophic waters is obvious. The reason for exclusion from areas with eutrophic waters lies in the fact that shrimp farms tend to use the same water body for water supply and effluent recipient. A location with an extremely wide diel dissolved oxygen fluctuation represents greatly impaired water quality. We feel, as did Clay (2004), that impaired sites usually made a disproportionately greater contribution to negative environmental impacts than do less impaired sites.
Reduction in water pollution is a particularly critical aspect of responsible aquaculture as well as responsible production in general. Although it does not appear possible to drastically reduce impacts of food production on terrestrial biodiversity, there is a greater possibly for lessening the potential for negative impacts on aquatic biodiversity. This situation is the result of terrestrial biodiversity impacts occurring almost entirely on the farm site while the aquatic biodiversity impacts occur off-site as a result of water pollution. Of course, a reduction in water pollution by a shrimp farm at some locations would not necessarily assure improvement in water quality and aquatic biodiversity. Obviously, certification cannot assure better water quality; it can just lessen pollution loads or exclude farms in compromised or in pristine environments.
Greater survival of shrimp in a pond typically leads to higher production and lower FCR (Chumnanka et al. 2015). Aside from rigorous biosecurity to assure disease free ponds and postlarvae at the time of stocking, the greatest reason for mortality is disease. Although various drugs and antibiotics are used by shrimp producers in efforts to prevent or treat diseases, there is no convincing evidence that such treatment are effective. The major reason for most of the common diseases in shrimp pond, and in aquaculture facilities in general, is impaired water quality that stresses the animals and predispose them to disease. The survival rate in ponds tends to be an indicator of whether biosecurity and water quality management is effective.
Certification programs tend to require farms to develop management plans for feeding, water quality maintenance, health management, etc. Proof that these plans have been made and are on file has no relationship to how well farms are managed. However, good survival and FCR are manifest evidence of effective feed, water quality, and health management – the plans may serve as guidelines, but their existence does not provide proof of implementation.
Maintenance of good water quality in feed-based shrimp ponds depends upon balancing the stocking and feeding rates with dissolved oxygen availability. It is seldom possible to have feeding rates above 30 kg/ha per day in un-aerated ponds and maintain acceptable water quality. Aeration should be applied at about 1 hp for each 10 kg/ha increment of daily feed input (Boyd and Tucker 2014). Adequate dissolved oxygen concentration is important for the respiration of shrimp and other aquaculture species and is necessary for oxidation of waste from feeding. To avoid stressing shrimp by low dissolved oxygen concentration and to lessen the possibility of ammonia, nitrite, and sulfide toxicity, the dissolved oxygen concentration should not fall below 3 mg/L in the early morning and be near saturation during the day (Boyd and Tucker 2014). A minimum dissolved oxygen concentration of 3 mg/L should be required as a certification standard.
Wild Fish Use
Shrimp feeds usually contain between 15 and 20% fish meal. This makes it difficult for producers to achieve a fish in – fish out ratio of 1.0 or less. Because shrimp aquaculture consumes a large amount of fish meal – about 27% of total aquaculture use in 2006 (Tacon and Metain 2008) – reduction in fish meal use should be a major concern in certification.
A great dilemma exists with respect to the amount of fish meal actually necessary in shrimp feed. A number of studies over the past decade have demonstrated that fish meal can be entirely replaced in shrimp feed with no reduction in FCR and production (Davis et al. 2008). However, to our knowledge, this research has basically been ignored by feed producers and farmers. An effort is needed to determine whether shrimp feeds containing no fish meal are equivalent to feeds with fish meal. If they are, it seems incumbent upon shrimp certification programs to require feeds with no fish meal or at least with a much lower fish meal inclusion rate than presently found in most shrimp feeds.
Energy is used directly for pumping water, aerating ponds, harvesting shrimp and several other purposes at the farm-level in shrimp aquaculture just as it is in most types of aquaculture. Energy also is embodied in aquaculture inputs – especially in feed. There is an urgent need to conserve energy, because fossil fuel, of which there is a finite supply, is the major energy source for most human endeavors, shrimp farming included. In addition, fossil fuel use is mainly responsible for the increasing carbon dioxide concentration of the atmosphere. Despite these realities, we believe that a new paradigm related to global energy sources is necessary (Boyd and McNevin 2015a), and in the meanwhile, it is acceptable to trade greater energy use for more efficient and less environmentally degrading shrimp production to meet the increasing demand for this product. Of course, shrimp farms should be required to conserve energy, but we do not see how it is possible to meet projected future demand for shrimp in a responsible way without using more energy. We would argue that shrimp are an unessential food item, and it likely makes sense to limit shrimp consumption. However, there is no precedent for regulating consumption of food or other agricultural products unless they represent health or societal risks perceived as extremely serious by an overwhelming majority of the populace.
Certification can lead to greater efficiency in use of most of the resources needed for shrimp aquaculture. It also can reduce negative environmental impacts at the farm-level. However, unless the majority of the shrimp production in an area becomes certified, the impacts of other farms may mask the benefits of certification. In some areas, certification of all shrimp farms would not result in positive environmental change, because of the negative impacts of other activities. Major improvements in environmental quality in some shrimp farming areas would require drastic changes in governmental regulation and enforcement of all activities within the coastal zone. Nevertheless, certification can make farms more resource use efficient and environmentally responsible. They also can serve to demonstrate the benefits of better practices.
Certification requires the producer to conduct various assessments, develop management plans, implement the certification program, monitor waste discharge, and contract with an accredited auditor to verify initial and continuing compliance. We suggest that all aspects of this complex and expensive procedure may have been desirable in the initial years of certification, but the requirements and standards of certification programs should be continually reviewed and revised in light of new findings, experiences, and technology.
Those involved with requirements for certification hopefully understand that the purpose of these programs is to lessen negative environmental impacts. This is accomplished by implementing good practices and monitoring to demonstrate whether a farm is compliant with the standards. Thus, the standards should not be the requirement to display written plans related to major indicators, but to demonstrate that the farm is compliant with verifiable standards related to each indicator. For example, preparation of an acceptable feed management plan filed in an accessible place should not be a standard despite being nice and convenient. The standard should be that the farm is compliant with good feed management by having an FCR equal to or less than the certification program standard for FCR. The same logic applies to all such management plans.
In a recent visit to a certified shrimp farm, we were required to check in, obtain and wear a visitor’s badge, fill out a personal data form, and answer queries about recent contact with livestock or shrimp and our health status. The buildings were numbered and spotlessly neat. The grounds also were neat and everything was in its place. We were ushered into a conference room where an array of assessments and management plans were displayed. But in discussions with farm management, it was immediately apparent from their responses to our questions that they were clueless about how anything other than the accounting aspects of the certification were to be achieved. They had no idea about how to minimize negative impacts.
The accounting aspects of certification programs are easy – just tedious and time consuming. These aspects should be minimized and emphasis placed on improving activities that have an environmental impact. We know that this statement should seem unnecessary, but all involved in certification should remember the purpose of the effort and not confuse appearance with effectiveness.
We believe that it is time to seriously reexamine the requirements and standards for shrimp farm certification and revise them to focus on the critical issues. Shrimp farm certification will not yield its potential benefits unless it actually leads to environmental improvement and the majority of shrimp aquaculture becomes certified. Simplification of the standards with emphasis on those causing the major improvements would lessen the cost of certification and make it more appealing to producers.
1School of Fisheries, Aquaculture and Aquatic
Sciences. Auburn University, Auburn, Alabama, 36849 USA.
2Director of Aquaculture World Wildlife Fund,
Washington, D.C. 20037 USA