Freshwater Prawns Macrobrachium rosenbergii

Transcription

1 Freshwater Prawns Macrobrachium rosenbergii Image Scandinavian Fishing Yearbook / Asia Ponds February 16, 2014 James H. Tidwell, Ph.D. Independent Research Analyst Disclaimer Seafood Watch strives to have all Seafood Reports reviewed for accuracy and completeness by external scientists with expertise in ecology, fisheries science and aquaculture. Scientific review, however, does not constitute an endorsement of the Seafood Watch program or its recommendations on the part of the reviewing scientists. Seafood Watch is solely responsible for the conclusions reached in this report.

2 2 About Seafood Watch Monterey Bay Aquarium s Seafood Watch program evaluates the ecological sustainability of wild-caught and farmed seafood commonly found in the United States marketplace. Seafood Watch defines sustainable seafood as originating from sources, whether wild-caught or farmed, which can maintain or increase production in the long-term without jeopardizing the structure or function of affected ecosystems. Seafood Watch makes its science-based recommendations available to the public in the form of regional pocket guides that can be downloaded from The program s goals are to raise awareness of important ocean conservation issues and empower seafood consumers and businesses to make choices for healthy oceans. Each sustainability recommendation on the regional pocket guides is supported by a Seafood Report. Each report synthesizes and analyzes the most current ecological, fisheries and ecosystem science on a species, then evaluates this information against the program s conservation ethic to arrive at a recommendation of Best Choices, Good Alternatives or Avoid. The detailed evaluation methodology is available upon request. In producing the Seafood Reports, Seafood Watch seeks out research published in academic, peer-reviewed journals whenever possible. Other sources of information include government technical publications, fishery management plans and supporting documents, and other scientific reviews of ecological sustainability. Seafood Watch Research Analysts also communicate regularly with ecologists, fisheries and aquaculture scientists, and members of industry and conservation organizations when evaluating fisheries and aquaculture practices. Capture fisheries and aquaculture practices are highly dynamic; as the scientific information on each species changes, Seafood Watch s sustainability recommendations and the underlying Seafood Reports will be updated to reflect these changes. Parties interested in capture fisheries, aquaculture practices and the sustainability of ocean ecosystems are welcome to use Seafood Reports in any way they find useful. For more information about Seafood Watch and Seafood Reports, please contact the Seafood Watch program at Monterey Bay Aquarium by calling

3 3 Guiding Principles Seafood Watch defines sustainable seafood as originating from sources, whether fished 1 or farmed, that can maintain or increase production in the long-term without jeopardizing the structure or function of affected ecosystems. The following guiding principles illustrate the qualities that aquaculture must possess to be considered sustainable by the Seafood Watch program: Seafood Watch will: Support data transparency and therefore aquaculture producers or industries that make information and data on production practices and their impacts available to relevant stakeholders. Promote aquaculture production that minimizes or avoids the discharge of wastes at the farm level in combination with an effective management or regulatory system to control the location, scale and cumulative impacts of the industry s waste discharges beyond the immediate vicinity of the farm. Promote aquaculture production at locations, scales and intensities that cumulatively maintain the functionality of ecologically valuable habitats without unreasonably penalizing historic habitat damage. Promote aquaculture production that by design, management or regulation avoids the use and discharge of chemicals toxic to aquatic life, and/or effectively controls the frequency, risk of environmental impact and risk to human health of their use. Within the typically limited data availability, use understandable quantitative and relative indicators to recognize the global impacts of feed production and the efficiency of conversion of feed ingredients to farmed seafood. Promote aquaculture operations that pose no substantial risk of deleterious effects to wild fish or shellfish populations through competition, habitat damage, genetic introgression, hybridization, spawning disruption, changes in trophic structure or other impacts associated with the escape of farmed fish or other unintentionally introduced species. Promote aquaculture operations that pose no substantial risk of deleterious effects to wild populations through the amplification and retransmission of pathogens or parasites. Promote the use of eggs, larvae, or juvenile fish produced in hatcheries using domesticated broodstocks thereby avoiding the need for wild capture. Recognize that energy use varies greatly among different production systems and can be a major impact category for some aquaculture operations, and also recognize that improving 1 Fish is used throughout this document to refer to finfish, shellfish and other invertebrates.

4 4 practices for some criteria may lead to more energy-intensive production systems (e.g. promoting more energy-intensive closed recirculation systems). Once a score and rank has been assigned to each criterion, an overall seafood recommendation is developed on additional evaluation guidelines. Criteria ranks and the overall recommendation are color-coded to correspond to the categories on the Seafood Watch pocket guide: Best Choices/Green: Are well managed and caught or farmed in environmentally friendly ways. Good Alternatives/Yellow: Buy, but be aware there are concerns with how they re caught or farmed. Avoid/Red: Take a pass on these. These items are overfished or caught or farmed in ways that harm other marine life or the environment.

5 5 Final Seafood Recommendation Freshwater Prawns Macrobrachium rosenbergii Asia Ponds Criterion Score (0-10) Rank Critical? C1 Data 6.67 GREEN C2 Effluent 8.00 GREEN NO C3 Habitat 7.30 GREEN NO C4 Chemicals 6.00 YELLOW NO C5 Feed 8.18 GREEN NO C6 Escapes 7.00 GREEN NO C7 Disease 6.00 YELLOW NO C8 Source 5.00 YELLOW C9X Wildlife mortalities GREEN NO C10X Introduced species escape 0.00 GREEN Total Final score 6.64 OVERALL RANKING Final Score 6.64 Initial rank YELLOW Red criteria 0 Interim rank YELLOW FINAL RANK Critical Criteria? NO YELLOW Scoring note scores range from zero to ten where zero indicates very poor performance and ten indicates the aquaculture operations have no significant impact. Summary The final numerical score for freshwater prawns grown in ponds in Asia is 6.64 out of 10 and with no red criteria the final ranking is Yellow Good Alternative.

6 6 Executive Summary Production of freshwater shrimps has expanded rapidly during the last decade. Current total production of all freshwater shrimp species exceeds 460,000 metric tons (MT) with a value of USD $1.9 billion. Global production of the Giant Malaysian Prawn or Giant River Prawn, Macrobrachium rosenbergii, in 2012 was 220,254 tons valued at USD 1.27 billion. Major producers of M. rosenbergii include China (57%), Bangladesh (19%), Thailand (11%), Vietnam (4%), India (3%), Taiwan (3%), and Myanmar (2%). Those currently exporting to the United States include Bangladesh, India, Vietnam and Thailand. Data availability and quality is high for this assessment. The main countries exporting freshwater prawns to the United States provide data through FAO reporting and actively publish in scientific journals. Additionally, the author of this report has extensive personal experience in the industry and has been widely published in the scientific literature. The score for Criterion 1: Data is 6.67 out of 10. A significant portion of freshwater prawn culture in Asia occurs in co-culture with rice, with the rice absorbing excess nutrients thus maintaining high water quality. Where monoculture of prawns is practiced, low standing biomass and few, if any, feed inputs mitigate the risks of nutrient enrichment. Additionally, ponds are static, meaning that there is no water exchange and effluent is only discharged once per cycle when ponds are drained for harvest. Because data show no evidence that effluents cause (or contribute to cumulative) local or regional impacts, the final numerical score for Criterion 2: Effluents is 8.00 out of 10. Prawn ponds in Asia are integrated with crops or built on previous pasture or cropland, and as such no sensitive habitats are impacted during construction or operation. Prawn farming results in minimal habitat impacts with no overall loss of ecosystem services or habitat functionality. Regulatory and management effectiveness, as well as enforcement of regulations, is shown to be moderate across the principal countries exporting prawns from Asia to the United States. Criterion 3 Habitat receives a numerical score of 7.30 out of 10. Chemical use in prawn farming is minimal as freshwater prawns are not as susceptible to bacterial and viral diseases as marine shrimp, and thus the need for chemical treatments is greatly reduced. While there are some historical examples of chemical use in Asian prawn farming, the species and production system has a demonstrably low need for chemical use and there is very infrequent discharge of water (i.e. once per production cycle at harvest). As such, the numerical score for Criterion 4 Chemical Use is 6 out of 10. Freshwater prawns utilize natural pond biota as food, so only low levels of supplemental pelleted feed are required. An average Feed Conversion Ratio (FCR) for M. rosenbergii in Asia is 2.3 and pelleted feeds consist of 30% protein, low fishmeal inclusion (2%), and no fish oil. The majority of feed ingredients (97%) are agricultural products and byproducts; however, it is unclear what proportion of these products is edible versus non-edible. Based on protein inputs

7 7 and outputs, prawn farming is calculated to result in a 49.9% net loss of protein. A total feed footprint of 2.04 hectares of land and ocean area is calculated to be necessary to produce the feed ingredients required to grow 1 ton of farmed prawns. The numerical score for Criterion 5: Feed is The escape risk from static ponds (defined as 0% 3% water exchange per day) is considered low to moderate and results in a score of 6 out of 10 for Factor 6.1a. Freshwater prawns are native to the Asian countries in which they are cultured, and some use of wild-caught juveniles and broodstock indicates that farmed stock are genetically similar to their wild counterparts. Because several countries covered in the scope of this assessment have either capture fisheries or intentional stocking programs, escapes are not expected to have significant ecological impacts. The numerical score for Criterion 6: Escapes is 7.00 out of 10. Freshwater prawns are resistant to many of the diseases common in marine shrimp aquaculture. This natural resistance is reinforced by the absence of water quality deterioration and physiological stress issues that are avoided through low stocking densities and low-input culture techniques. Though some disease outbreaks on prawn farms in Asia have been known to occur, the risk of amplification and transmission of diseases from farms to wild populations is low to moderate, so the numerical score for Criterion 7: Disease is 6.00 out of 10. Prawn production in Asia relies on a combination of hatchery produced and wild post-larvae (PLs) for pond stocking. Broodstock for hatcheries are also sourced from both natural waters and production ponds. For the purposes of this assessment, 50% of Asian prawn production is presumed to be sourced from hatcheries, thus the numerical score for Criterion 8: Source of Stock is 5.00 out of 10. The principal predators on Asian prawn farms are wild fish and freshwater tortoises. Due to the low-density biomass of prawns in ponds, avian and mammalian predators are not common and several studies have concluded that wildlife interactions are of no concern. However, ponds have the potential for wildlife mortality and therefore a minor adjustment based solely on precaution is warranted, so the numerical score for Exceptional Criterion 9X is 1.00 out of 10. There is some limited cross-border shipping of prawn larvae in Asia, but because freshwater prawns are native to the region, the source and destination are not considered to be ecologically distinct water bodies. Therefore, the risk of escape of an unintentionally introduced species is negligible. As a result, Exceptional Criterion 10X is unnecessary to be scored and no adjustment is applied (i.e., a score of 0 out of 10). The final numerical score for freshwater prawns grown in ponds in Asia is 6.64 out of 10, and with no red criteria, the final ranking is Yellow Good Alternative.

8 8 Table of Contents About Seafood Watch... 2 Guiding Principles... 3 Final Seafood Recommendation... 5 Executive Summary... 6 Introduction... 9 Analysis Scoring guide Criterion 1: Data quality and availability Criterion 2: Effluents Criterion 3: Habitat Criterion 4: Evidence or Risk of Chemical Use Criterion 5: Feed Criterion 6: Escapes Criterion 7: Disease; pathogen and parasite interactions Criterion 8: Source of Stock independence from wild fisheries Criterion 9X: Wildlife and predator mortalities Criterion 10X: Escape of unintentionally introduced species Acknowledgements References Appendix 1: Data points and all scoring calculations... 33

9 9 Introduction Scope of the analysis and ensuing recommendation Species Macrobrachium rosenbergii Geographic coverage Asia Production Methods Ponds either monoculture or integrated with rice *Note: this report uses the terms shrimp and prawn interchangeably. Species Overview Freshwater prawns are a rather large group of decapod crustaceans within the genus Macrobrachium. There are about 230 species, and all live at least a portion of their lives in freshwater (Holthuis and Ng 2010). The focus of this analysis is the species Macrobrachium rosenbergii; common names include the Giant River Prawn and the Giant Malaysian Prawn. This species must have access to brackish water to reproduce. In nature, they live in rivers and tributaries but must migrate to bays and estuaries where the eggs hatch and undergo larval stages in brackish water ( 12 ppt). The larvae then metamorphose into post-larvae, which inhabit freshwater and migrate back up the rivers (Brown et al. 2010). Its optimum temperature range is between 26 o C and 32 o C (78 90 o F) and it dies when temperatures drop below 1215 o C (55 60 o F) (Boyd and Zimmerman 2010). They are opportunistic benthic omnivores feeding mainly on aquatic invertebrates such as snails and insect larvae, but also plant materials, detritus, and fishes. In aquaculture, freshwater prawns can be grown on feeds with lower protein and higher carbohydrate levels than marine shrimp or other carnivorous farmed species (D Abramo and New 2010). Production statistics Production of freshwater shrimp has expanded rapidly during the last decade. In 2012, production of M. rosenbergii was 220,254 t valued at USD 1.27 billion (FAO 2014). The main producers of M. rosenbergii in 2012 included China (57%), Bangladesh (19%), Thailand (11%), Vietnam (4%), India (3%), Taiwan (3%), and Myanmar (2%). All of these are Asian countries. Only Bangladesh, India, Thailand, and Vietnam export to the U.S. However, Vietnam does not separate prawn and marine shrimp production in its export statistics, so quantifying the Vietnamese freshwater prawn contribution to total U.S. shrimp imports is not possible. Production methods in Vietnam will be briefly described in the different sections but not

10 10 included in scoring because their relative contribution cannot be determined and Vietnam represents such a small fraction of global M. rosenbergii production. Import and export sources and statistics All of the available import/export records for shrimp are not specific down to the species level, so figures for M. rosenbergii are unable to be disaggregated from the following information. It is expected that the majority of shrimp cited in the following data are marine species (e.g., L. vannamei, P. monodon). According to the National Fisheries Institute (2012), shrimp is the top seafood consumed in the U.S. During 2011, the average consumption of shrimp in the U.S. was 1.9 kg (4.2 lb) per person, a rate 60% greater than that of the second-most consumed seafood, canned tuna at 1.2 kg (2.6 lb). The National Marine Fisheries Service (NMFS 2011) reports that the volume of shrimp imported into the U.S. in 2011 was 575,110 MT. Valued at $5.2 billion, shrimp imports accounted for 31% of the total value of edible imports. The U.S. is also an exporter of shrimp, almost all of which emanates from wild harvest. In 2011, total shrimp exports from the United States equaled 12 MT (USDA-ERS 2013) and were purchased by Canada (24%), Denmark (13%), Vietnam (9%), Mexico (6%) and China (5%) (NMFS 2011). Currently, over 90% of the shrimp consumed in the U.S. is imported. Unfortunately, import statistics lump marine and freshwater shrimps into a total shrimp category and do not break out freshwater shrimp statistics. All the freshwater shrimp imported into the U.S. are from Asia and in frozen form. Although China is the largest producer, they do not appear to currently export to the United States because their production is entirely consumed domestically (Hongtuo et al. 2012). Currently, it appears that the largest exporter to the United States is Bangladesh (4,400 MT) (Wahab et al. 2012; DoF 2010). Notably, a large portion of Bangladeshi production is probably not truly farmed but is wild captured or stock-enhanced capture. Other exporters to the United States include India (1,348 MT) (Nair and Salin 2012), Thailand (144 MT) (Na-Nakorn and Jintasataporn 2012; Department of Fisheries 2010) and Vietnam. Much, if not most, of the U.S. market for imported freshwater prawns appears to be made up of consumers of Asian descent or restaurants serving Asian food (New and Kutty 2010). Common and market names Freshwater prawns, Freshwater shrimp, Scampi Product forms Frozen tails, frozen whole

11 11 Analysis Scoring guide With the exception of the exceptional factors (3.3x and 6.2X), all scores result in a zero to ten final score for the criterion and the overall final rank. A zero score indicates poor performance, while a score of ten indicates high performance. In contrast, the two exceptional factors result in negative scores from zero to minus ten, and in these cases zero indicates no negative impact. The full Seafood Watch Aquaculture Criteria that the following scores relate to are available here The full data values and scoring calculations are available in Appendix 1 Criterion 1: Data quality and availability Impact, unit of sustainability and principle Impact: poor data quality and availability limits the ability to assess and understand the impacts of aquaculture production. It also does not enable informed choices for seafood purchasers, nor enable businesses to be held accountable for their impacts. Sustainability unit: the ability to make a robust sustainability assessment Principle: robust and up-to-date information on production practices and their impacts is available to relevant stakeholders. Criterion 1 Summary Data Category Relevance (Y/N) Data Quality Score (0-10) Industry or production statistics Yes Effluent Yes 5 5 Locations/habitats Yes Predators and wildlife Yes Chemical use Yes 5 5 Feed Yes Escapes, animal movements Yes Disease Yes 5 5 Source of stock Yes Other (e.g. GHG emissions) No n/a n/a Total 60 C1 Data Final Score 6.67 GREEN

12 12 Brief Summary Data availability and quality is high for this assessment. The main countries exporting freshwater prawns to the United States provide data through FAO reporting and actively publish in scientific journals. Additionally, the author of this report has extensive personal experience in the industry and has been widely published in the scientific literature. The score for Criterion 1: Data Quality and Availability is 6.67 out of 10. Justification of Ranking Despite China being the largest producer, their production is not currently exported to the United States. The main sources of prawns imported into the United States include Bangladesh, India, Thailand, and Vietnam. All these countries actively provide data through FAO reporting, actively publish in scientific journals either directly or indirectly, or publish through collaborators providing in-country assistance. Papers concerning production methods, feeds used, production levels, feed efficiencies, and drug use can be found in the primary literature. All are available in English. Many papers review commercial production, locations, and facilities, and any use of drugs during different stages of production; see (Ahmed & Garnett 2010) (Wahab et al. 2012) (Ahmed, Brown & Muir 2008) (Kutty, Nair & Salin 2009) (Nair and Salin 2012) (Na-Nakorn and Jintasataporn 2012). Additionally, the author of this report has extensive experience in the industry and has relied on this expertise to bridge any data gaps that may exist in the scientific literature. The numerical score for Criterion 1: Data Quality and Availability is 6.67 out of 10.

13 13 Criterion 2: Effluents Impact, unit of sustainability and principle Impact: aquaculture species, production systems and management methods vary in the amount of waste produced and discharged per unit of production. The combined discharge of farms, groups of farms or industries contributes to local and regional nutrient loads. Sustainability unit: the carrying or assimilative capacity of the local and regional receiving waters beyond the farm or its allowable zone of effect. Principle: aquaculture operations minimize or avoid the production and discharge of wastes at the farm level in combination with an effective management or regulatory system to control the location, scale and cumulative impacts of the industry s waste discharges beyond the immediate vicinity of the farm. Criterion 2 Summary Effluent Evidence-Based Assessment C2 Effluent Final Score 8.00 GREEN Brief Summary A significant portion of freshwater prawn culture in Asia occurs in co-culture with rice, with the rice absorbing excess nutrients, thus maintaining high water quality. Where monoculture of prawns is practiced, low standing biomass and few, if any, feed inputs mitigate the risks of nutrient enrichment. Additionally, ponds are static, meaning that there is no water exchange and effluent is only discharged once per cycle when ponds are drained for harvest. Because data show no evidence that effluents cause (or contribute to cumulative) local or regional impacts, the final numerical score for Criterion 2: Effluents is 8.00 out of 10. Justification of Ranking The majority or entirety of prawns grown in Asia that come to U.S. markets are from Bangladesh, India, Vietnam, and Thailand. Overall, a large proportion of the freshwater prawns produced in Asian countries for export to the U.S. are produced in combination or rotation with rice (Kutty et al. 2009). Bangladesh and India both widely utilize co-cultures with rice and polyculture with Asian or Indian carps (Wahab et el. 2012) (Nair and Salin 2012). Most operations rely on prawns that utilize natural pond biota for nutrition, and these operations either do not feed a pelleted feed or only provide supplemental feeds (Wahab et el. 2012) (Nair and Salin 2012). If supplemental feeds are provided, they are relatively low-protein feeds. The rice takes up any waste nitrogen from the prawns (Ahmed and Garnett 2010). When the rice fields are drained, these nutrients are likely tied up as plant biomass, and water quality should not differ significantly from receiving waters. In Thailand, monoculture is the principal prawn farming method (Na-Nakorn and Jintasafa 2012). Ponds are drained once per year and allowed to dry. However, low maximum biomass densities of <2,000 kg/ha make negative effluent impacts, or the risk of effluent impacts,

14 14 unlikely (Na-Nakorn and Jintasafa 2012). However, even this moderate production level is actually a cumulative total over several selective partial harvests. Total standing crop biomass likely never exceeds 1,500 kg/ha, further supporting the conclusion that the risk of water quality degradation is minor. The low impact on water quality by prawn production, even at their highest production rates, was documented in (Tidwell et al. 2004), who compared different prawn production technologies in ponds and evaluated associated water quality variables. No levels of concern were identified, even at the highest prawn production and feeding rates. According to (D Abramo, Silva and Frinsko 2009), [T]he overall quality of the discharge water at harvest is as good as, or possibly better than, the quality of the water originally used to fill the pond. Low biomass, polyculture with rice, little or no supplemental feed, and ponds that only discharge water at harvest all mitigate potential effluent impacts from Asian prawn farms. Because data show no evidence that effluents cause (or contribute to cumulative) local or regional impacts, the numerical score for Criterion 2: Effluents is 8.00 out of 10.

15 15 Criterion 3: Habitat Impact, unit of sustainability and principle Impact: Aquaculture farms can be located in a wide variety of aquatic and terrestrial habitat types and have greatly varying levels of impact to both pristine and previously modified habitats and to the critical ecosystem services they provide. Sustainability unit: The ability to maintain the critical ecosystem services relevant to the habitat type. Principle: aquaculture operations are located at sites, scales and intensities that cumulatively maintain the functionality of ecologically valuable habitats. Criterion 3 Summary Habitat parameters Value Score F3.1 Habitat conversion and function 9.00 F3.2a Content of habitat regulations 3.00 F3.2b Enforcement of habitat regulations 3.25 F3.2 Regulatory or management effectiveness score 3.90 C3 Habitat Final Score 7.30 GREEN Critical? NO Brief Summary Prawn ponds in Asia are integrated with crops or built on previous pasture or cropland, so no sensitive habitats are affected during construction or operation. Prawn farming results in minimal habitat impacts with no overall loss of ecosystem services or habitat functionality. Regulatory and management effectiveness, as well as enforcement of regulations, is shown to be moderate across the principal countries exporting prawns from Asia to the United States. Criterion 3: Habitat receives a numerical score of 7.30 out of 10. Justification of Ranking Factor 3.1. Habitat conversion and function The impact of habitat conversion for aquaculture purposes is measured in terms of the change in the system s ability to provide ecosystem services. Most prawn production in Bangladesh (the largest exporter to the United States) involves either integration with rice culture, polyculture with finfish, or the utilization of wetlands and rice fields in a system locally known as gher (Ahmed et al. 2008). All these systems represent the use of existing facilities, or relatively minor modifications of existing systems, and are unlikely to negatively impact ecosystem services or habitat functionality. In Thailand, purpose-built aquaculture ponds are used. Many are multi-purpose/multi-species ponds and not specifically built for prawn production (Na-Nakorn and Jintasafa 2012). In India,

16 16 there was a period from 2000 to 2005 of increased conversion of agricultural fields to prawn farming. Converted terrestrial crops included rice paddies, sugar cane, and coconut orchards. Also, development of prawn production in relatively arid regions of India was shown to be depleting groundwater (Nair and Salin 2012). However, after 2007 many farms were taken out of prawn production and reverted to their original crops. According to (Nair and Salin 2012) there have been no reports of prawn production in India causing any adverse effects on the environment in general or on any conflicting social issues thereof, unlike the case of the marine shrimp sector. Any habitat impacts resulting from prawn aquaculture in earthen ponds will be minimal and accordingly maintain habitat functionality and ecosystem services. Therefore, Factor 3.1 scores 9 out of 10. Factor 3.2. Habitat and farm siting management effectiveness (appropriate to the scale of the industry) Most production either utilizes existing multi-purpose/multi-species aquaculture ponds or is integrated into existing rice production infrastructure and management schemes. While there has been some conversion of cropland in India, this practice appears to have stopped and even reversed (Nair and Salin 2012). There is evidence of government oversight in all the Asian countries currently exporting to the U.S., with governments encouraging production of freshwater prawns in Bangladesh (Wahab et al. 2012) and India (Nair and Salin 2012). Recently, there is evidence of the licensing of individual producers and siting permits in Bangladesh and India. (Wahab et al. 2012) reported that the Bangladesh Department of Fisheries has taken the initiative to register prawn farms, depots, ice factories and processing plants through the United Nations Industrial Development Organization (UNIDO) project. As part of the program, 154,872 prawn and shrimp farms have been registered (Ahmed 2010). A news article in the New Indian Express (March 18, 2013) stated that the registration of ponds for freshwater aquaculture has been made mandatory in the Indian state of Andhra Pradesh. For Factor 3.2a, Regulatory or Management Effectiveness, the score of 3 out of 5 indicates that there is oversight to control or prevent habitat loss or overwhelming of ecological services. This is supported by the regulatory and permitting structures described in the FAO National Aquaculture Legislation Overview (NALO 2014) Country Factsheets for India and Thailand. The factsheet for Bangladesh indicates that their Environmental Conservation Rules of 1997 do not govern aquaculture. However, (Wahab et al. 2012) indicates that the Bangladesh Department of Fisheries now registers prawn ponds. In Vietnam, their Decision No. 224/1999/QD-TTg (Approving the Aquaculture Development Program for the country for the period) declares its first underpinning principle to be sustainable development closely associated with the protection of the ecological environment (FAOLEX 2014). However, a permit system on siting or on effluent of individual or multiple farms is not evident.

17 17 A score of 3.25 out of 5 for Siting Regulatory or Management Enforcement indicates there is the will and authority on the side of government agencies to impose limits or mandates when needed. Overall, the final score for Factor 3.2, Habitat and Farm Siting Management Effectiveness (appropriate to the scale of the industry) receives a numerical score of 3.9 out of 10. When the scores for Factors 3.1 and 3.2 are combined, the final numerical score for Criterion 3: Habitats is 7.30 out of 10.

18 18 Criterion 4: Evidence or Risk of Chemical Use Impact, unit of sustainability and principle Impact: Improper use of chemical treatments impacts non-target organisms and leads to production losses and human health concerns due to the development of chemical-resistant organisms. Sustainability unit: non-target organisms in the local or regional environment, presence of pathogens or parasites resistant to important treatments. Principle: aquaculture operations by design, management or regulation avoid the discharge of chemicals toxic to aquatic life, and/or effectively control the frequency, risk of environmental impact and risk to human health of their use. Criterion 4 Summary Chemical Use parameters Score C4 Chemical Use Score 6.00 C4 Chemical Use Final Score 6.00 YELLOW Critical? NO Brief Summary Chemical use in prawn farming is minimal because freshwater prawns are not as susceptible to bacterial and viral diseases as marine shrimp, and thus the need for chemical treatments is greatly reduced. Although there are some historical examples of chemical use in Asian prawn farming, the species and production system has a demonstrably low need for chemical use and there is very infrequent discharge of water (i.e., once per production cycle at harvest). Thus, the numerical score for Criterion 4: Chemical Use is 6.00 out of 10. Justification of Ranking Freshwater prawns are not as susceptible to bacterial and viral diseases as are marine shrimp (Pillai, Johnson, and Bueno 2010). They are also raised at much lower biomass densities, limiting instances of physiological stress and water quality deterioration, which in turn decrease the risk of disease outbreak and the subsequent requirement for chemical treatment. The primary use of antibiotics appears to be small amounts of oxytetracycline and disinfectants, such as formalin, during the hatchery phase (New and Kutty 2010). Some chemicals such as chlorine and tea seed cake (saponin) are used to sterilize the bottom soils and eliminate finfish from ponds prior to prawn stocking (New and Kutty 2010). Normally, little if any chemicals are used during prawn growout. But in 2006, prawns being exported from Bangladesh were found to have residues of nitrofurans. Strong measures were implemented because Bangladesh has a need to protect, and even grow, its export markets in the European Union and United States (Wahab et al. 2012). Of 133 fish processing plants in

19 19 Bangladesh, 68 are EU approved (Wahab et al. 2012). As stated earlier, the Department of Fisheries in Bangladesh has an initiative to register prawn farms, depots, ice factories, and processing plants through the United Nations Industrial Development Organization, including any drug use. Based on these efforts, it would appear that the use of unapproved chemicals in Bangladesh will or has already waned. In Thailand, chemical residues (e.g., sulfadiazine and nitrofuran) were also reported in prawns intended for export markets. However, with the implementation of Good Aquaculture Practices (GAP), the problem has diminished (Na-Nakorn and Jintasafa 2012). Though specific data may be limited, the species and production system has a demonstrably low need for chemical use. Additionally, there is a lack of evidence of impacts to non-target organisms, and the production system has very infrequent discharge of water (i.e., once per production cycle at harvest). So the risk of discharge of active chemicals, and the impact associated with such discharge, is minimal. Therefore, the numerical score for Criterion 4: Chemical Use is 6.00 out of 10.

20 20 Criterion 5: Feed Impact, unit of sustainability and principle Impact: feed consumption, feed type, ingredients used and the net nutritional gains or losses vary dramatically between farmed species and production systems. Producing feeds and their ingredients has complex global ecological impacts, and their efficiency of conversion can result in net food gains, or dramatic net losses of nutrients. Feed use is considered to be one of the defining factors of aquaculture sustainability. Sustainability unit: the amount and sustainability of wild fish caught for feeding to farmed fish, the global impacts of harvesting or cultivating feed ingredients, and the net nutritional gains or losses from the farming operation. Principle: aquaculture operations source only sustainable feed ingredients, convert them efficiently and responsibly, and minimize and utilize the non-edible portion of farmed fish. Criterion 5 Summary Feed parameters Value Score F5.1a Fish In: Fish Out ratio (FIFO) F5.1b Source fishery sustainability score F5.1: Wild Fish Use 9.37 F5.2a Protein IN F5.2b Protein OUT F5.2: Net Protein Gain or Loss (%) F5.3: Feed Footprint (hectares) C5 Feed Final Score 8.18 GREEN Critical? NO Brief Summary Freshwater prawns utilize natural pond biota as food and thus only low levels of supplemental pelleted feed are required. An average Feed Conversion Ratio (FCR) for M. rosenbergii in Asia is 2.3 and pelleted feeds consist of 30% protein, low fishmeal inclusion (2%), and no fish oil. The majority of feed ingredients (97%) are agricultural products and byproducts; however, it is unclear what proportion of these products are edible versus non-edible. Based on protein inputs and outputs, prawn farming is calculated to result in a 49.9% net loss of protein. A total feed footprint of 2.04 hectares of land and ocean area is calculated to be necessary to produce the feed ingredients required to grow 1 ton of farmed prawns. The numerical score for Criterion 5: Feed is 8.18.

21 21 Justification of Ranking Factor 5.1. Wild Fish Use Prawns are efficient omnivorous foragers and utilize natural foods produced in the ponds for a substantial portion of their nutrition (Tidwell et al. 1997). Combined with their relatively low biomass densities, prawns in Asia often receive no feed at all or are fed at only supplementary levels. The feeds used are often farm-made or locally produced using agricultural products and byproducts (Salin et al. 2009). They can be grown with diets containing no fish meal and high percentages of grains or grain byproducts (D Abramo and New 2010). The majority of production in Bangladesh and India is in combination with rice, either in rotation or concurrently. Foraging prawns can actually be beneficial to the rice by removing rice pests, such as snails. Most production in Thailand is based on manufactured feeds. Because of their ability to efficiently utilize natural pond biota for nutrition, prawns can achieve relatively low Feed Conversion Ratios (FCR), even in fed systems. For Bangladesh, an FCR of 2.75 was reported (Wahab et al. 2012), while India reported an average FCR of 1.9 (Nair and Salin 2012) and Thailand 2.0 (Na-Nakorn and Jintasafa 2012). A weighted mean of these values gives an average FCR of 2.3 for Asian countries exporting prawns to the U.S. Pelleted feeds utilized in Asia contain 2% fishmeal inclusion and no fish oil. Utilizing a global average of 22.5% fishmeal yield, the fish in:fish out (FIFO) value for fishmeal is calculated to be 0.20 (see Appendix 1 for calculations). This corresponds to an initial FIFO score of 9.49 out of 10. This FIFO score can be adjusted based on the relative sustainability of the source of wild fish (SSWF). Though it is recognized that only low levels of fishmeal are included, no information on the source of wild fishmeal used in prawn feeds was available at the time of this assessment, so a deduction of 6 is dictated by the SFW criteria based on unknown source fisheries and unknown sustainability. This corresponds to a SSWF adjustment of 0.12 and a final Factor 5.1 score of 9.37 out of 10, driven mainly by the low inclusion level of marine ingredients. Factor 5.2. Net Protein Gain or Loss With respect to protein inputs, pelleted prawn feeds contain 30% protein; this protein consists of aquatic feed ingredients (fishmeal), non-edible sources (processing byproducts from fish, animals, or crops), and edible crop sources. Since fishmeal itself is 60% protein, fishmeal constitutes 1.2% of the total protein in the feed. Feeds in Asia are often farm-made or locally produced using agricultural products and byproducts (Salin et al. 2009), and many prawn feeds contain high percentages of grains or grain byproducts (D Abramo and New 2010). However, it is not clear from the literature what percentage of these feed ingredients are fit for human consumption versus non-edible. Thus, this assessment has split the remaining 98.8% of feed protein, with half assumed to be from edible crop sources and the other half assumed to be from non-edible processing byproducts.

22 22 With respect to protein outputs, the protein content of whole harvested farmed prawns is 18% (Boyd 2007) and the edible yield is 40%. Seafood Watch criteria presume that 50% of nonedible byproducts from harvested prawns are used for other food production. As shown in the calculations in Appendix 1, freshwater prawn farming in Asia results in a 49.9% net loss of protein. This net protein loss is driven by the presumed inclusion of edible crop ingredients and results in a Factor 5.2 score of 5 out of 10. Factor 5.3. Feed Footprint With respect to feed footprint, the 2% fishmeal inclusion and 0% fish oil inclusion results in an ocean area of 1.20 hectares being required to produce the aquatic ingredients necessary to grow 1 ton of farmed prawns (see Appendix 1 for calculations). There is a 97% inclusion level of crop feed ingredients and 0% inclusion of land animal ingredients; the remaining 1% of feed ingredients consists of vitamins, minerals, and/or other feed additives. This level of terrestrial ingredient inclusion corresponds to a land area of 0.85 hectares being required to produce the ingredients necessary to grow 1 ton of farmed prawns. When the ocean and land areas are combined, the total feed footprint is calculated to be 2.04 hectares, corresponding to a Factor 5.3 score of 9 out of 10. This high score is driven by the prawns efficient foraging ability, low levels of aquatic ingredients, and high levels of crop ingredients. The final Criterion 5: Feed score is 8.18 out of 10. This high score is based on the utilization of natural food products in the ponds, low feeding rates, low levels of fishmeal inclusion, no inclusion of fish oil, and a small feed footprint.

23 23 Criterion 6: Escapes Impact, unit of sustainability and principle Impact: competition, genetic loss, predation, habitat damage, spawning disruption, and other impacts on wild fish and ecosystems resulting from the escape of native, non-native and/or genetically distinct fish or other unintended species from aquaculture operations. Sustainability unit: affected ecosystems and/or associated wild populations. Principle: aquaculture operations pose no substantial risk of deleterious effects to wild populations associated with the escape of farmed fish or other unintentionally introduced species. Criterion 6 Summary Escape parameters Value Score F6.1 Escape Risk 6.00 F6.1a Recapture and mortality (%) 0 F6.1b Invasiveness 9 C6 Escape Final Score 7.00 GREEN Critical? NO Brief Summary The escape risk from static ponds (0% 3% water exchange per day) is considered low to moderate and results in a score of 6 out of 10 for Factor 6.1a. Freshwater prawns are native to the Asian countries where they are cultured, and some use of wild-caught juveniles and broodstock indicates that farmed stock are genetically similar to their wild counterparts. Because several countries in the scope of this assessment have either capture fisheries or intentional stocking programs, escapes are not expected to have significant ecological impacts. The numerical score for Criterion 6: Escapes is 7.00 out of 10. Justification of Ranking Factor 6.1a. Escape risk Prawn production ponds in Asia have low daily water exchange rates (0% 3%) and are only drained at harvest. The Seafood Watch criteria consider these systems to have a low to moderate escape risk (score of 6). Production in Bangladesh and India is in low-lying areas and escape is possible during flooding (especially during monsoon season) or rice paddy draining. However, no large escapes are documented in the literature. The escape risk score can be adjusted based on evidence of recapture or direct mortality of escapes. Since no evidence in this regard is available, no adjustment has been applied.

24 24 Based on the low daily water exchange in prawn ponds in Asia, the Factor 6.1a escape risk score is 6 out of 10. Factor 6.1b. Invasiveness M. rosenbergii is native to the Asian countries evaluated in this assessment and prawns are not considered to be an invasive species. In fact, there have been no documented cases of prawns that were introduced for aquaculture establishing a breeding population outside of their native range (New et al. 2010). Though some hatchery production of juvenile prawns exists, there is still reliance on wildcapture fisheries for both broodstock and post-larvae (PLs) (see Criterion 8: Source of Stock). Thus, prawns have not been domesticated enough to differ significantly from the genetic integrity of wild indigenous populations. For the purposes of this assessment, prawns are considered to be one-generation hatchery raised (i.e., their parents are wild-caught). This corresponds to a score of 4 out of 5 for Factor 6.1b Part A, indicating that this native species is still genetically similar to wild populations. Both native and non-native species have the potential to affect surrounding ecosystems when they escape from farm systems. However, for the countries evaluated here, unintentional escapes are not considered either detrimental to or to significantly compete with local fish or crustacean populations, especially given that large-scale escape events of the indigenous species are rare. For example, in Vietnam, escapes are considered to positively impact wild populations and naturally enhance the capture fisheries (New and Kutty 2010). Thailand has a stocking program for stock enhancement (New and Kutty 2010). In India, releases from hatcheries make a substantial contribution to capture fisheries (Nair and Salin 2012). Because escapes do not significantly impact surrounding ecosystems, the score for Factor 6.1b, Part C is 5 out of 5.

25 25 Criterion 7: Disease; pathogen and parasite interactions Impact, unit of sustainability and principle Impact: amplification of local pathogens and parasites on fish farms and their retransmission to local wild species that share the same water body Sustainability unit: wild populations susceptible to elevated levels of pathogens and parasites. Principle: aquaculture operations pose no substantial risk of deleterious effects to wild populations through the amplification and retransmission of pathogens or parasites. Criterion 7 Summary Pathogen and parasite parameters Score C7 Biosecurity 6.00 C7 Disease; pathogen and parasite Final Score 6.00 YELLOW Critical? NO Brief Summary Freshwater prawns are resistant to many of the diseases common in marine shrimp aquaculture. This natural resistance is reinforced by the absence of water quality deterioration and physiological stress, issues that are avoided through low stocking densities and low-input culture techniques. Though some disease outbreaks on prawn farms in Asia have been known to occur, the risk of amplification and transmission of diseases from farms to wild populations is low to moderate, so the numerical score for Criterion 7: Disease is 6.00 out of 10. Justification of Ranking Freshwater prawns are considered to be highly resistant to diseases, even those (such as white spot and yellowhead) that have at times devastated marine shrimp production. Combined with a natural resistance is the fact that prawns are raised at much lower densities than marine shrimp, thus decreasing water quality deterioration and physiological stress conditions (New et al. 2010). Despite this resistance, some diseases resulted in problems for prawn farmers in Asia. Major outbreaks of balloon disease (branchiostegal blister disease, BBD) (Pillai et al. 2005) and White Tail Disease (WTD) occurred in India in the late 1990s and early 2000s (Bonami et al. 2005) (Pillai and Bonami 2012). In Thailand, WTD was also a problem; however, prawn hatcheries were much more affected than growout ponds (Na-Nakorn and Jintasafa 2012). Prophylactic use of antibiotics was historically reported in Thailand, but with changes in management approaches, this practice has diminished (Na-Nakorn and Jintasafa 2012). Because the farms only discharge water once per production cycle, and the outbreak of disease is relatively uncommon, the risk of transmission of disease agents from ponds to wild

26 populations is low to moderate. Thus, the final numerical score for Criterion 7 Disease is 6.00 out of

27 27 Criterion 8: Source of Stock independence from wild fisheries Impact, unit of sustainability and principle Impact: the removal of fish from wild populations for on-growing to harvest size in farms Sustainability unit: wild fish populations Principle: aquaculture operations use eggs, larvae, or juvenile fish produced from farmraised broodstocks thereby avoiding the need for wild capture Criterion 8 Summary Source of stock parameters Score C8 % of production from hatchery-raised broodstock or natural (passive) settlement 50 C8 Source of stock Final Score 5.00 YELLOW Brief Summary Prawn production in Asia relies on a combination of hatchery-produced and wild post-larvae (PLs) for pond stocking. Broodstock for hatcheries are also sourced from both natural waters and production ponds. For the purposes of this assessment, 50% of Asian prawn production is presumed to be sourced from hatcheries, so the numerical score for Criterion 8: Source of Stock is 5.00 out of 10. Justification of Ranking Dependence on wild stocks for seedstock or broodstock varies widely among the Asian countries being evaluated. For example, Bangladesh sources roughly 85% of its post-larvae (PL) from wild populations and 15% from hatcheries (Wahab et al. 2012), while 100% of juveniles and PLs in India and Thailand are produced in hatcheries (Nair and Salin 2012) (Na-Nakorn and Jintasafa 2012). There is also significant variation with respect to the source of broodstock. For example: in Bangladesh, hatcheries source their broodstock primarily from the wild (Wahab et al. 2012); in India, from both the wild and from production ponds; and in Thailand, only from production ponds. For the purposes of this assessment, a regional-wide conservative estimate of 50% of production is presumed to be produced from hatchery-reared broodstock. Despite a reliance on wild populations, the capture of broodstock from the wild does not appear to negatively impact wild prawn populations. Because 50% of production is presumed to emanate from hatchery-reared broodstock, the numerical score for Criterion 8: Source of Stock is 5.00 out of 10.