Seafood Watch Seafood Report

U.S. Farmed Hybrid Striped Bass Morone chrysops X Morone saxatilis

(Photo by Gerald Ludwig, Courtesy of USDA-ARS)

Final Report August 31, 2005

Brendan O’Neill Private Consultant

Seafood Watch® Farmed Hybrid Striped Bass Report August 31, 2005

About Seafood Watch® and the Seafood Reports

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 Internet (seafoodwatch.org) or obtained from the Seafood Watch® program by emailing [email protected]. 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® Fisheries 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 1-877-229-9990.

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.

Seafood Watch® and Seafood Reports are made possible through a grant from the David and Lucile Packard Foundation.

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Executive Summary

Hybrid striped bass, a cross between striped bass (Morone saxatilis) and white bass (Morone chrysops), is an important fish in U.S. aquaculture. Commercial-scale production of hybrid striped bass for the foodfish market began in the mid-1980s and grew to over a million pounds of annual production by 1990. In 2000, hybrid striped bass production was ranked fifth in U.S. aquaculture production and fourth in value of all U.S. cultured foodfish. Production of hybrid striped bass primarily takes place in pond systems, which are used most often in the Southeast United States, but tank production also makes up a large portion of overall production. In general, the systems used to farm hybrid striped bass are inherently low risk and not believed to cause widespread environmental harm when well managed.

The hybrid striped bass aquaculture industry is dependent on marine resources in feeds, leading some to question its overall sustainability. Advancements in feed formulations in recent years, however, have led to decreased dependence on wild fish for feed ingredients, to the extent that the wild fish input to farmed fish output ratio is now estimated to be below 2:1. While no evidence of frequent or large-scale escapes of hybrid striped bass from aquaculture facilities exists, there are potential risks and caution must be taken to ensure that the environment and wild fish populations are not negatively impacted by escapes. Different systems pose different levels of risk, with pond systems carrying a higher level of risk than closed or semi-closed tank systems. Overall, there is little risk of transfer or introduction of diseases and parasites from hybrid striped bass farms to wild fish and the discharge of wastes is not believed to be a major problem. Management of the hybrid striped bass aquaculture industry is effective and well regulated; however, the increased adoption of best management practices could potentially further improve the environmental performance of the industry.

Overall, U.S. farmed hybrid striped bass ranks as a “Best Choice” according to Seafood Watch® criteria for the sustainability of farm-raised species. There are no conservation criteria that are of “High” or “Critical” conservation concern and 3 or more criteria are of “Low” conservation concern (3 for pond systems and 4 for closed systems).

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Table of Sustainability Ranks

Conservation Concern Sustainability Criteria Low Moderate High Critical Use of Marine Resources √ (all) Risk of Escaped Fish to √ √ (ponds) Wild Stocks (closed systems) Risk of Disease and Parasite Transfer to Wild Stocks √ (all) Risk of Pollution and Habitat Effects √ (all)

Management Effectiveness √ (all)

About the Overall Seafood Recommendation: • A seafood product is ranked “Avoid” if two or more criteria are of High Conservation Concern (red) OR if one or more criteria are of Critical Conservation Concern (black) in the table above. • A seafood product is ranked “Good Alternative” if the five criteria “average” to yellow (Moderate Conservation Concern) OR if four criteria are of Low Conservation Concern (green) and one is of High Conservation Concern. • A seafood product is ranked “Best Choice” if three or more criteria are of Low Conservation Concern (green) and the remaining criteria are not of High or Critical Conservation Concern.

Overall Seafood Recommendation:

Farmed hybrid striped bass (pond culture and tank culture):

Best Choice Good Alternative Avoid

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Introduction

In the late 1980s and early 1990s, as commercial catches of wild striped bass were declining, a new fish began to replace it in markets and restaurants. This new fish was a farmed variety of the popular game fish; however, the “farmed striped bass” was actually a hybrid, a cross between two closely related species, one of which was the striped bass.

While several types of hybrid striped bass exist, the crosses used most often in foodfish production involve the striped bass (Morone saxatilis) and the white bass (Morone chrysops). There are two of these crosses that are of primary interest to aquaculturists: palmetto bass, which is created when eggs from striped bass are crossed with sperm from white bass (Harrell and Webster 1997); and sunshine bass, which is created when the reciprocal cross is made, striped bass sperm with white bass eggs. Both crosses have improved characteristics over either parent, including faster growth, better survival, improved disease resistance, and greater tolerance for variable water quality conditions (Morris et al. 1999; Harrell 1997a). Most cultured hybrid striped bass are Sunshine bass, primarily because it is easier to obtain and handle female white bass than female striped bass.

Both striped bass and white bass belong to the Moronidae family of fishes (Moyle and Cech 2000). This family, also known as the temperate basses, is comprised of six species of fish, four of which are native to North America. Temperate basses are found in freshwater and saltwater and are considered important game fishes. General features of these fish include medium to large size, elongated body shape, a large mouth, small teeth, two opercular spines, and a spiny dorsal fin (Jenkins and Burkhead 1994).

The striped bass is the best known member of the family Moronidae. It is a popular sport fish and is often referred to as “rockfish” in the mid-Atlantic region. The native range of the striped bass extends along the Atlantic Coast from New Brunswick to Florida and along the Gulf Coast from Florida to Texas (Hodson 1989a). Its range has been extended through introductions on the west coast of North America, where it has established reproducing populations, as well as through introductions in many reservoirs where it can establish landlocked populations or be maintained through continued stocking (Hodson 1989a). Striped bass can reach sizes of over 70 pounds. Populations of striped bass on the Atlantic Coast went through dramatic declines in the 1980s, but strict regulations and improved management helped restore the populations. Today, striped bass support important sport and commercial fisheries on the Atlantic Coast.

The white bass is closely related to the striped bass. Also a popular sport fish, it is a smaller member of the family Moronidae, usually reaching sizes of 4 to 5 pounds (Hodson 1989a). The white bass is native to much of the Mississippi River basin and has been introduced to many areas outside its native range (Guy et al. 2002).

The culture of striped bass began in the early 1900s as a way to enhance commercial and recreational fisheries (Stickney 1996). These efforts were later abandoned, but a desire to control forage fish populations and provide recreational opportunities in southern reservoirs created a renewed interest in culturing striped bass for stocking in the 1950s and 1960s (Stickney 1996). With these efforts came the first crosses of striped bass and white bass to create the

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hybrids that would become the focus of both stocking efforts and commercial aquaculture of striped bass (Stickney 1996).

Production Commercial scale production of hybrid striped bass for the foodfish market began in the mid- 1980s (Carlberg et al. 2000). The first large-scale farm used above-ground tank culture and geothermal groundwater in southern California, but pond culture operations soon followed in North Carolina, South Carolina, Louisiana, Maryland, Mississippi, and Texas (Carlberg et al. 2000). By 1990, over 1.5 million pounds of striped bass were produced annually in the United States (Carlberg et al. 2004) and in 2000, hybrid striped bass production was ranked fifth in U.S. aquaculture production, behind catfish, salmon, trout, and tilapia, and fourth in value of all foodfish grown in the United States (Carlberg et al. 2000).

A review of the current hybrid striped bass aquaculture industry is provided on the Striped Bass Growers Association (SBGA) website (http://ag.ansc.purdue.edu/aquanic/sbga/). According to industry statistics, 61 facilities produced a total of 11.5 million pounds of hybrid striped bass in 2004 (Carlberg et al. 2004). Nearly half of total production was from facilities in the Western region of the United States, where the majority of production was from 2 facilities utilizing tank production methods and the rest of production came from pond culture. Over 2.3 million pounds of hybrid striped bass were produced in 2004 in the U.S. Southeast region (Louisiana, Arkansas, Mississippi, Tennessee, Alabama, Florida), nearly all of it coming from only 6 pond operations. Three tank farms also contributed a small amount of production. In the Mid-Atlantic region (Georgia, South Carolina, and North Carolina) over 3 million pounds of hybrid striped bass were produced, with all production coming from ponds. Facilities in the Midwest and the Northeast regions each produced less than half a million pounds of hybrid striped bass in 2004 (Carlberg et al. 2004).

Types of aquaculture systems used Three aquaculture systems are used to farm hybrid striped bass: ponds, cages in ponds, and tanks. Of the 61 facilities that produced hybrid striped bass in the U.S. in 2004, 44 used ponds, 10 used cages in ponds, and 7 used tanks (Carlberg et al. 2004). Pond production accounted for over 7 million pounds of production, or over 60% of total production, while the 7 farms that used tanks accounted for over 4 million pounds, or nearly 40% of total production. A single large farm in California accounted for approximately 80% of total hybrid striped bass production in tanks (J.M. Carlberg, Kent SeaTech, personal communication). A third type of production system, cages in ponds, was used by ten hybrid striped bass producers, exclusively in the upper Midwest region, but these producers were much smaller in scale and produced a total of only 130,000 pounds of fish.

Since the early 1990s there has been a shift in production practices as overall production has increased. When hybrid striped bass farming first began, most of the production was from tanks, but since the early to mid 1990s, tank production has remained relatively constant while pond production has increased dramatically. Also in the early years of striped bass and hybrid striped bass farming, there was interest in growing fish in coastal netpens (Williams et al. 1981), while more recently there has been interest in future production of the fish in offshore facilities (Hubbs

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SeaWorld Research Institute, undated). Currently, however, there is no production of hybrid striped bass from either coastal netpens or offshore aquaculture facilities in the United States.

The tank systems used by hybrid striped bass growers in the United States represent a wide range of systems. Kent SeaTech of California, for example, a pioneer in the industry and one of the largest hybrid striped bass companies in the country, uses a semi-recirculating tank system, in which 80% of the water used in the aquaculture operation is recycled (J.M. Carlberg, Kent SeaTech, personal communication). The Kent SeaTech system is also integrated with agriculture; wastewater that is discharged is delivered to nearby farmers for irrigation of crops, helping to reduce water use and impacts on the environment. Kent SeaTech is by far the largest hybrid striped bass farmer using tanks in the United States, as it produces about 80% of the total amount of tank-farmed hybrid striped bass in the U.S. Other growers using tank systems, all of which farm hybrid striped bass on a much smaller scale, may use systems that range from closed to more flow-through in nature.

Pond farming of hybrid striped bass is now the dominant method of production. The ponds used to grow hybrid striped bass are primarily located in the Southeast United States and are similar to catfish ponds. Maintenance of good water quality in hybrid striped bass ponds is very important (Hodson 1989b). Temperature and dissolved oxygen must be monitored often and aeration is usually required to avoid problems with low dissolved oxygen. To prevent cannibalism, hybrid striped bass are often sorted by size, with different-sized fish placed in different ponds. Problems with cannibalism also mean that farmers must completely drain ponds at the end of each production cycle to ensure the removal of all fish in the ponds, a key difference between hybrid striped bass farming and catfish farming. As an alternative to completely draining ponds, some farmers have begun treating ponds with a piscicide after harvest to eliminate any remaining fish before restocking ponds (EPA 2002).

There are four phases in the production of striped bass (Kohler 2000; Hodson 1995). In the first, or hatchery phase, broodstock are spawned and embryos are incubated. Unlike the production of many other aquacultured species, the farming of hybrid striped bass usually depends on the collection of wild broodstock for spawning, though domestication efforts are underway (Kohler 2000; R.G. Hodson, NC Sea Grant, personal communication). After the hatchery phase is phase I, in which larval fish are raised in ponds for 30 – 45 days. At this stage, the fish feed on zooplankton and the ponds must be fertilized with a mixture of organic and inorganic fertilizers to ensure the correct plankton communities are present. Next is phase II, in which fish are harvested from phase I ponds, graded into different size classes, and stocked into ponds or tanks for the first growing season. Phase II ponds are not fertilized, but instead the fish begin to eat manufactured feeds. Many commercial hybrid striped bass growers avoid the tedious work of the hatchery phase and phase I phases by purchasing phase II fish for growout from fingerling producers. In the final phase, phase III, the fish are harvested from phase II ponds and stocked into larger ponds for the second growing season, at the end of which they are harvested at market size. Farmed hybrid striped bass can reach market size of about one pound in about 15 – 18 months (Hodson 1989b).

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Scope of the analysis and the ensuing recommendation: The analysis in this seafood report encompasses hybrid striped bass farmed in the U.S. that is available in the market to U.S. consumers. Hybrid striped bass also are farmed in Israel, Taiwan, China, and possibly other countries, but fish from these countries are believed to be rarely, if ever, available to U.S. consumers (J.M. Carlberg, Kent SeaTech, personal communication). Wild and stocked striped bass, white bass, and hybrids are not considered in this evaluation.

Availability of Science

The farmed hybrid striped bass industry is relatively young; however, a large and growing body of science exists on many topics involved in the production of hybrid striped bass. Feed formulation and improvement, production methods, and disease control are research areas that have received much attention. Continued research at academic institutions and government research stations will likely continue to supply the industry with scientific advances to improve production and help the industry progress in the coming years. As with many forms of aquaculture, however, very little comprehensive research has been conducted and very little scientific literature is available on the environmental impacts of hybrid striped bass farming in the United States.

Market Availability

Common and market names: Farmed hybrid striped bass are sold as hybrid striped bass, sunshine bass, palmetto bass, and wiper. When used for sushi or sashimi, striped bass is commonly sold as suzuki.

Seasonal availability: Farmed hybrid striped bass is available year-round.

Product forms: Farmed hybrid striped bass is available live, as fresh whole fish, and as fresh fillets.

Import and export sources and statistics: No official statistics are available on the import and export of farmed hybrid striped bass, but according to a long-time member of the industry, imports of hybrid striped bass are very infrequent (J.M. Carlberg, Kent SeaTech, personal communication).

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Analysis of Seafood Watch® Sustainability Criteria for Farm-raised Species

Criterion 1: Use of Marine Resources

Worldwide, aquaculture production includes a wide variety of species, ranging from autotrophic seaweeds, to filter-feeding shellfish and finfish, to omnivorous and carnivorous shellfish and finfish (FAO 2004). Several recent reports have raised concerns about the feed requirements of the carnivorous species grown in aquaculture, specifically that they may be contributing to a net loss in fish protein (Naylor et al. 2000; Weber 2003). The dependence on wild fish for feed ingredients could result in increased pressure on wild fisheries used to make the feeds.

While some have criticized aquaculture of carnivores as an inefficient use of resources, claiming that it takes several pounds of small forage fish to produce a single pound of farmed fish (Weber 2003; Naylor et al. 2000), other researchers and members of the aquaculture industry have pointed out that aquaculture systems are much more efficient than natural systems (Tidwell and Allan 2001). In terrestrial systems in nature, conversion efficiency from one trophic level to the next is believed to be around 10:1 and it has become common practice for those defending the farming of carnivores to favorably compare these seemingly inefficient natural systems with the feed conversion efficiency of aquaculture, generally in the range of 1:1 – 3:1. This may be an over-simplification, however, as it fails to take into account that aquaculture of carnivores is an industrial system that has externalized many of its costs, while the natural conversion from one trophic level to another forms an integral part of a functioning ecosystem, providing much more than food for human consumption. Additionally, little is known about trophic conversion efficiencies in aquatic systems, though they are believed to be better than in terrestrial systems. Regardless, it is important to note that aquaculture is a very efficient means of producing protein, far more efficient than most other animal agriculture systems (Forster and Hardy 2001).

Much of the protein and fat in feeds for carnivorous fish are sourced from reduction fisheries for wild fish such as anchovy, herring, menhaden, and mackerel. These fisheries, like many around the world, are believed to be at their maximum sustainable levels, leading some to question the sustainability of further developing an industry based on feeding wild-caught fish to farmed fish (Naylor et al. 2000; Weber 2003; Naylor and Burke 2005). The fishmeal and fish oil obtained from these fisheries are in high demand and are used in many different feed applications, including poultry and pigs (IFFO 2001). Clearly, the issue of feeding wild fish to farmed animals is not isolated to the aquaculture industry. In 2000, aquaculture used 35% and 54% of the global supplies of fishmeal and fish oil, respectively (IFFO 2001). Other agricultural uses, such as chickens and pigs, use a smaller amount of fishmeal and fish oil in their feed formulations, but since their industries are so large, they consumed a large percentage of the overall supply. Future projections, however, estimate that the aquaculture feed industry will use an increasingly large share of the global supply of fishmeal and fish oil, possibly as high as 56% of the fishmeal and 97% of the fish oil by 2010 (IFFO 2001).

Protein alternatives, including plant-based proteins and those derived from processing wastes, will have to be developed if aquaculture production of organisms requiring feeds is to expand (Hardy and Tacon 2002; Watanabe 2002). While there is a growing realization that this change will need to take place and much of the work has begun, it will be a major challenge for the

8 Seafood Watch® Farmed Hybrid Striped Bass Report August 31, 2005 aquaculture industry to continue to grow in the future while reducing its dependence on wild fish for feeds.

Farmed hybrid striped bass feed use Hybrid striped bass are carnivorous and require a high protein diet. Additionally, like many other aquaculture industries, feed costs in hybrid striped bass farming account for the largest proportion of variable costs. This means that appropriate diets not only affect efficiency, but also profitability (Gatlin 1997). Diet formulations and other areas of nutrition and feed science, including the use of alternative proteins, are areas of much research interest (for examples, see: Gallagher 1994; Robinette et al. 1997; Webster et al. 2000).

Hybrid striped bass feeding behavior After hatching, young hybrid striped bass live on nutrients from their yolk sacs for about four or five days (Gatlin 1997). They then feed on natural prey items, primarily zooplankton such as cladocerans and copepods, until they reach a length of about 100 mm at which time they become primarily piscivorous (Gatlin 1997). When in the farm setting, hybrid striped bass can be trained to accept artificial feeds after just a few weeks in phase I ponds.

Inclusion rates Reliable figures on actual inclusion rates of fishmeal and fish oil used in feeds in the hybrid striped bass industry are not readily available. In a 1997 review of nutrition and feeding of striped bass and hybrid striped bass, Gatlin suggested a “model diet formulation” for the growout of striped bass and hybrid striped bass. The model diet included 33% fishmeal and 5% fish oil, as well as 31% soybean meal and 30% wheat flour. Since diet formulations in aquaculture feeds are evolving rapidly, estimates from 1997 are not likely an accurate reflection of diet composition today. Conversations with experts in the field to identify present day inclusion rates yielded estimates similar to the 1997 “model diet” for fish oil inclusion (3 – 5%), but lower estimates for the current fishmeal inclusion in hybrid striped bass diets, generally in the 10% to 20% range (D.M. Gatlin, Texas A&M University, personal communication; R.G. Hodson, NC Sea Grant, personal communication; J.M. Carlberg, Kent SeaTech, personal communication). For the purpose of completing the calculations in this report, a fishmeal inclusion rate of 15% and fish oil inclusion rate of 4% are used.

To avoid double-counting, calculations in this report are performed separately for fishmeal and fish oil and the larger of the two final calculations are used to determine the wild fish input to farmed fish output ratio. Some researchers have added the fishmeal and fish oil inclusion rates together for a total inclusion rate and then used this figure in calculating the fish input to fish output ratio, but this fails to take into account that reduction fisheries are for both fishmeal and fish oil. In other words, the same fish are used to produce fishmeal and fish oil, so adding the inclusion rates together ignores the fact that they are products from the same fisheries and in effect double-counts the amount of wild fish inputs consumed.

Other important figures for calculating the wild fish input to farmed fish output ratio are the yield rates of fishmeal and fish oil from reduction fisheries. Yield rates can vary based on the species of fish, season, condition of fish, and efficiency of reduction plants (Tyedmers 2000). For this seafood report, a fishmeal yield rate of 22% is used. This has been suggested by Tyedmers

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(2000) as a reasonable year-round average yield rate and means that 4.5 units (kg, lb, mt, etc.) of wild fish from reduction fisheries are needed to produce 1 unit of fishmeal. Additionally, this report uses a fish oil yield rate of 12%, or 8.3 units of wild fish to produce 1 unit of fish oil, which was suggested by Tyedmers (2000) as a representative year-round average for Gulf of Mexico menhaden.

Feed conversion ratio The feed conversion ratio (FCR), or the ratio of feed inputs (dry weight) to farmed fish output (wet weight), for striped bass may vary considerably depending on the quality of the feeds and the type of farming system used, with ponds having a slightly higher FCR than tank systems (R.G. Hodson, NC SeaGrant, personal communication). Estimates of FCR are available in the scientific literature (Gallagher 1994; Robinette et al. 1997; Webster et al. 2000), but these generally are the result of controlled experiments and often use investigational diets that may not accurately reflect actual industry practices. However, such studies indicate that alternative proteins could be included in diets for hybrid striped bass, potentially making the industry significantly less dependent on marine resources. A 2001 publication by the North Carolina Department of Agriculture and Consumer Services included hybrid striped bass farming budgets that assumed FCRs in the range of 2.2:1 – 2.4:1 (NCDACS 2001). In 2000, an industry publication indicated that slightly lower FCRs of 2:1 were the industry norm, but added that it is a high priority of the industry to reduce this figure considerably (Carlberg et al. 2000). This report uses an FCR of 2:1.

Ratio of wild fish to farmed hybrid striped bass Base on the figures above, the following calculations were completed to estimate the wild fish input to farmed fish output ratio for farmed hybrid striped bass (HSB):

Conversion for fishmeal:

4.5 kg of wild fish X .15 kg fishmeal X 2.0 kg feed = 1.35 kg wild fish per kg of HSB 1 kg fishmeal 1 kg feed 1 kg HSB

Conversion for fish oil:

8.3 kg of wild fish X .04 kg fish oil X 2.0 kg feed = 0.664 kg wild fish per kg of HSB 1 kg of fish oil 1 kg feed 1 kg of HSB

As noted above, these calculations are not added together, as that would result in double- counting the wild fish inputs required to grow the farmed fish. Instead, the larger of the two values, 1.35, represents the ratio of wild fish input to farmed hybrid striped bass output.

Stock status of the reduction fishery It is generally believed that populations of fish used in most reduction fisheries are stable (Hardy and Tacon 2002; Huntington et al. 2004); however, concerns have been raised about the potential for increased demand from expanding industries for farmed carnivorous fish and the effect this demand would have on those fish populations (Weber 2003). Additionally, concerns have been raised about their role in the ecosystem and how the removal of these fish could affect ecosystem

10 Seafood Watch® Farmed Hybrid Striped Bass Report August 31, 2005 dynamics. These concerns are especially focused on the importance of these fish as prey items for predators such as birds and mammals (Huntington et al. 2004). Catches have been stable, with the exception of El Niño years, when declines in catches, especially in fish off the western coast of South America, contribute to declines in overall availability of fish used for reduction (Hardy and Tacon 2002). Worldwide landings of fish for reduction have ranged from 19 metric tons (mt) to 28 mt in the past decade, yielding an annual average of 6 – 7 mt of fishmeal and 1.2 mt of fish oil (Hardy and Tacon 2002).

Broodstock collection Domestication of broodstock is a high research priority for the hybrid striped bass industry (Carlberg et al. 2000; Harrell and Webster 1997). Currently, a national domestication program is underway, but the industry still relies on some wild fish for broodstock (J.M. Carlberg, Kent SeaTech, personal communication; R.G. Hodson, NC Sea Grant, personal communication). Collection of wild fish primarily involves a small number of female white bass, mostly from the Lake Erie commercial fishery, and it may involve the collection of some male striped bass, though these may come from captive stocks in some instances (Hodson, NC Sea Grant, personal communication). There is no indication that the collection of white bass for broodstock has caused negative impacts on wild populations. The commercial catch of white bass in Lake Erie, of which the catch for farm broodstock makes up a very small portion, varies from year to year because of good and poor year-classes and changes in fishing effort, but the population appears to be stable (ODW 2004). Mean commercial landings of white bass from Lake Erie over the past 10 years (1994 – 2003) were 238,472 pounds. At current levels, the collection of wild white bass for broodstock is not a conservation concern (K. Kayle, Ohio DNR, personal communication). Likewise, the collection of a relatively small number of wild striped bass for broodstock, when required, is not likely to cause any negative impacts. The wild striped bass population on the Atlantic Coast has made a dramatic recovery since the 1980s, is now at high levels, and is not being overfished (ASMFC 2003). Additionally, wild striped bass has been analyzed and deemed a “Best Choice” by Seafood Watch (see www.SeafoodWatch.org for more info).

Synthesis Farmed hybrid striped bass diets contain fishmeal and fish oil from wild reduction fisheries, but at moderate levels relative to other farmed carnivorous fish species, such as Atlantic salmon. Inclusion levels of fishmeal and fish oil in diets for hybrid striped bass, however, are higher than those for catfish and tilapia. The ratio of wild fish used in aquaculture feed to farmed hybrid striped bass produced, according to the calculations above, is 1.35, which is considered of “Moderate” conservation concern based on Seafood Watch® program criteria.

Use of Marine Resources Rank:

Low Moderate High Critical

Criterion 2: Risk of Escaped Fish to Wild Stocks

Worldwide, aquaculture has become one of the leading vectors of exotic species introduction (Carlton 1992; Carlton 2001), and concerns have been raised about the ecological impacts of

11 Seafood Watch® Farmed Hybrid Striped Bass Report August 31, 2005 escapes of farmed fish into the wild (Volpe et al. 2000; Weber 2003; Youngson 2001; Naylor et al. 2001). Most criticism, however, has been directed at open aquaculture systems, primarily netpens and cages used in coastal waters, especially those used to farm Atlantic salmon. Myrick (2002) described six potential negative impacts of escaped farmed fish: genetic impacts, disease impacts, competition, predation, habitat alteration, and colonization. Escaped farmed fish can negatively impact the environment and wild populations of fish whether they are native or exotic to the area in which they are farmed, and the probability of significant ecological impact increases as the number of escaped individuals increases (Myrick 2002). Different aquaculture systems carry different levels of risk of escapes, with open systems such as salmon farms carrying the greatest risk, and systems that are more closed to the surrounding environment having lower risk. The risks of impact to the environment from escaped farmed organisms can be reduced through proactive measures such as careful selection of sites, species, and systems; training of personnel; and the development of contingency plans and monitoring systems (Myrick 2002).

Frequency and impact of hybrid striped bass escapes Due to the nature of the farming facilities (inland ponds and tanks) utilized in farming hybrid striped bass, the inherent risk of escapes from these aquaculture facilities is considerably lower than from other systems, especially netpens and cages. Escapes of hybrid striped bass from commercial aquaculture facilities do not occur often or in great numbers; however, the escape of fish from pond aquaculture systems has resulted in some notable introductions of exotic species, including several species of Asian carps, which are now a major nuisance (Naylor et al. 2001).

The amount of hybrid striped bass that could potentially escape from aquaculture facilities is considerably smaller than the amount of fish introduced through the large-scale intentional stocking efforts of the species by many government agencies. Stocking of hybrid striped bass and striped bass, which provide important recreational fisheries and help control overabundant forage fish populations, grew rapidly in the 1970s and 1980s (Axon and Whitehurst 1985). A survey of state fisheries management agencies in the early 1980s found that fisheries for striped bass, hybrid striped bass, or both had been established in at least 279 lakes in 34 states (Axon and Whitehurst 1985). These stocking efforts, when carried out under effective fisheries management, likely involve a low risk to the environment, but do have the potential to cause negative impacts. Intentionally stocked hybrid striped bass have the potential to compete with native species and introduce foreign genetic material into established populations of parental species (Avise and van den Avyle 1984; Patrick and Moser 2001; Harrell 1997b). Hybrid striped bass are fertile and backcrossing of stocked fish with parental species in the wild has occurred, leading to concerns of introgression of foreign genes (Avise and van den Avyle 1984; Lutz 2004). Escapes from hybrid striped bass aquaculture facilities could potentially carry similar risks. To eliminate these concerns, some have suggested the use of sterile triploid hybrid striped bass for stocking and farming where naturally producing species of striped and white bass occur (Harrell 1997b). It should be noted, however, that to date, there is no evidence of negative impacts from commercially farmed hybrid striped bass escapes, but since there are potential risks to the environment and wild populations of fish, caution should be taken to limit escapes and their impact.

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Synthesis There is no evidence of frequent or large-scale escapes of hybrid striped bass from farming facilities. However, there are potential risks from such escapes and caution must be taken to ensure that the environment and wild populations of fish are not negatively impacted by escapes. To evaluate the risks involved, the different culture systems should be examined separately.

Recirculating and semi-recirculating systems for hybrid striped bass aquaculture pose the lowest risk of harming wild fish populations through escapes. Farms using these systems include one very large facility in California and possibly a few other farms that operate on much smaller scales. These farms can be considered closed or semi-closed systems and, therefore, receive a rank of “Low” in terms of risk of escapes.

Hybrid striped bass farms that use ponds, including fingerling producers, pose a slightly higher risk of impacting wild fish through escapes. This is primarily because pond production systems cannot be considered fully closed systems; they are susceptible to overflowing, are completely drained after each production cycle, and may release small amounts of discharge when water exchange is required. Those factors, plus the fact that escaping hybrid striped bass could negatively impact wild populations of fish, including through genetic introgression, lead to a rank of “Moderate” risk for pond systems.

If hybrid striped bass were farmed in open systems such as coastal netpens and cages, as has been suggested by Williams et al. (1981), then an even greater level of conservation concern would arise. Currently, open systems are not in use in the farming of hybrid striped bass, but there is interest among some researchers and members of the industry in farming striped bass in this way (Hubbs SeaWorld Research Institute, undated; Hogans 1994). Using standard technology, this development would be viewed as posing a “High” risk of impacts from escapes.

Since a small amount of hybrid striped bass is sold live, mostly to Asian markets, there is an additional risk that fish could be released or escape during transport or by other means. It should be noted that there is no evidence of this occurring and there is no evidence of negative impacts from such escapes, but the live-trade of hybrid striped bass does provide another potential avenue, though an unlikely one, for farmed fish to find their way into natural ecosystems.

Risk of Escaped Fish to Wild Stocks Rank:

Closed/semi-closed systems:

Low Moderate High Critical

Pond systems:

Low Moderate High Critical

13 Seafood Watch® Farmed Hybrid Striped Bass Report August 31, 2005

Criterion 3: Risk of Disease and Parasite Transfer to Wild Stocks

In recent years, concerns have been raised over the spread of disease and parasites from aquaculture to wild fish populations (Krkosek et al. 2005; Weber 2003; Paone 2000; Carr and Whoriskey 2004). Like the issue of escapes, the risk of the spread of disease appears to be dependent on the type of aquaculture system used, with open systems carrying the greatest risk. Blazer and LaPatra (2002) identified three types of potential interactions of cultured and wild fish populations in terms of pathogen transmission. First, the importation of exotic organisms for culture can introduce pathogens to an area. Second, movement of cultured fish, native and non- native, can introduce new pathogens or new strains of pathogens. Lastly, intensive fish culture, which can include crowding, poor living conditions, and other stressors, can lead to the amplification of pathogens that already exist in wild populations as well as their transmission between wild and cultured populations.

Very little is known about the distribution and frequency of diseases in wild fish populations (Blazer and LaPatra 2002). Unlike aquaculture, where dead or dying fish are easily observed and diagnosed, sick fish in the wild often go unnoticed since they likely become easy prey for predators. Without the background knowledge of what diseases existed before an aquaculture facility is put in place, it is difficult to determine whether aquaculture is responsible for introducing or transferring a disease to wild populations. Additionally, as with exotic species introduction, there are other means of disease introduction besides aquaculture, including ballast water transfer, fish processing, and fish transport.

Closed and semi-closed aquaculture systems have the lowest potential for releasing pathogens into the environment (Blazer and LaPatra 2002). Wastewater from these systems can be treated and intermediate hosts and carriers, for example birds, snails, and worms, can be excluded from the culture facility. Pond and flow-through systems, on the other hand, pose some risk of pathogen transfer to wild fish populations. Both pond and flow-through aquaculture systems can spread diseases through the discharge of wastewater and escapes of farmed fish. Pond systems also are open to intermediate hosts, which can transport pathogens from one farm pond to another and potentially between farms and the wild.

Diseases of hybrid striped bass Hybrid striped bass are susceptible to several common disease-causing organisms, primarily bacteria (Kohler 2000). Bacterial diseases found in hybrid striped bass farming include columnaris, vibriosis, and mycobacteriosis (Hodson 1995; Kohler 2000). Fungal diseases and parasites can also be problematic in hybrid striped bass farming. No drugs are approved by the U.S. Food and Drug Administration (FDA) for the treatment of disease in hybrid striped bass farming; however, compounds of “low regulatory priority,” such as acetic acid, carbon dioxide, hydrogen peroxide, ice, and sodium chloride may be used (Hodson 1995).

Synthesis Overall, there is little risk of transfer or introduction of diseases and parasites from hybrid striped bass farms to wild fish. There is no evidence of transfer or introduction of diseases or parasites as a result of commercial hybrid striped bass farming. Hybrid striped bass farms that employ closed or semi-closed technology pose the lowest risk of transferring diseases and parasites to

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wild fish. Closed and semi-closed systems recycle much of their water and discharge very little untreated waste directly into nearby bodies of water, thereby significantly reducing the chances that they could transfer diseases and parasites to wild populations. Pond systems, on the other hand, discharge water during draining and when water exchange is required, and are open to intermediate hosts such as birds and snails. When these factors are taken into account, the risk of disease and parasite transfer for pond systems is slightly higher than it is for closed systems, but it is the opinion of the author that the difference in disease transfer risk between different production systems is not enough to warrant different scores on this criterion. Since to date there is no evidence of disease problems spreading from hybrid striped bass farms to wild fish, and all hybrid striped bass farming systems appear to pose little risk of transferring diseases and parasites to wild fish populations, the overall risk for this criterion is deemed minor.

Risk of Disease Transfer to Wild Stocks Rank:

Low Moderate High Critical

Criterion 4: Risk of Pollution and Habitat Effects

Pollution from aquaculture facilities is a conservation concern as waste products from aquaculture have the potential to impact the surrounding environment (Gowen et al. 1990; Costa- Pierce 1996; Beveridge 1996). Like other forms of agriculture, aquaculture creates waste that can be released into the environment; however, aquaculture wastes often are released untreated directly into nearby bodies of water. Pollution from aquaculture can take several forms, including nutrients, suspended solids, and chemicals. In recent years, biological pollution, including the release of exotic species of farmed fish into the wild, has become recognized as an aspect of waste discharge (Byrd 2003).

The potential for impact from aquaculture wastes largely depends on the type of system used (Costa-Pierce 1996). Intensive systems, especially those that are open to natural bodies of water, have the greatest potential for polluting the environment, while there is little potential impact from closed or semi-closed systems, in which discharges are infrequent and wastes can be treated (Costa-Pierce 1996). Most aquaculture waste is the result of excess feed or fish feces as only small portions of the nutrients in aquaculture feed are actually converted to edible fish flesh (Beveridge 1996). Depending on the species of fish and the quality of the feed, as little as 20% of the nitrogen and 30% of the phosphorus in feed is converted to flesh, leaving as much as 80% of the nitrogen and 70% of the phosphorus as waste (Beveridge 1996). In open aquaculture systems, such as those used for salmon farms, this waste is discharged directly into natural bodies of water, while in closed systems, wastes can be treated or potentially used for other purposes such as irrigation and fertilization of plants.

In pond aquaculture systems, wastewater is discharged when the systems overflow or when the ponds are drained. Natural processes in the ponds remove much of the waste, however, and as a result the levels of pollutants in discharge water never reach the theoretical levels based on calculations of inputs and outputs (Tucker et al. 2002). Tucker et al. (2002) suggested that a basic principle of pond aquaculture is that the production intensity must stay within the limits of

15 Seafood Watch® Farmed Hybrid Striped Bass Report August 31, 2005

the system to assimilate and remove wastes. In other words, farmers must allow natural processes to maintain good water quality in ponds. Tipping the natural processes out of balance, by farming too many fish, adding too much food, or doing anything else that could result in more waste being produced than can be handled by the biological, chemical, and physical processes in the pond, could degrade water quality and affect production efficiency. The three primary substances of concern in pond aquaculture wastewater are: solids or particulate matter, which can be deposited in receiving waters and impact benthic conditions; organic matter, which can increase oxygen demand; and nutrients, most importantly nitrogen and phosphorus, which can stimulate growth of aquatic plants and phytoplankton (Tucker et al. 2002). In their review of warmwater aquaculture pond effluents, Tucker et al. (2002) suggested that catfish pond effluents contain environmentally insignificant quantities of chemicals because only EPA-approved chemicals are used, use of chemicals is infrequent, and the long residence time of ponds allows for breakdown of chemicals before discharge. Accordingly, chemical pollution from hybrid striped bass ponds should not be a problem since few chemicals are used in hybrid striped bass pond aquaculture and pond dynamics are similar to those in catfish ponds.

Effluent effects from hybrid striped bass farming

Tank systems Tank facilities, which can range from closed systems to systems that are more flow-through in nature, account for approximately 40% of total U.S. hybrid striped bass production. The largest of the tank facilities, Kent SeaTech in southern California, which accounts for about 80% of U.S. hybrid striped bass tank production, utilizes an innovative semi-recirculating system designed to reduce water use and limit impacts on the environment. The Kent SeaTech system recycles 80% of its water and delivers wastewater discharges to nearby farmers for irrigation of crops (J.M. Carlberg, Kent SeaTech, personal communication).

Pond systems Pond facilities account for over 60% of total U.S. production of hybrid striped bass. Little information is available, however, regarding the effluent discharges from these ponds and their impact on the environment. A review of the literature found only one study that provides insight into the nature of hybrid striped bass pond effluents. In a study of 20 commercial hybrid striped bass ponds, great variation in the quality of effluents was found from pond to pond (Tucker 1998). Several indicators of water quality, most notably suspended solids, total nitrogen, and biochemical oxygen demand, were found in higher concentrations in pond samples than in source water; the poor water quality of these ponds has a great potential for impacting the environment.

Tucker et al. (2002) suggested that the principles derived from the extensive study of catfish ponds should apply to all warmwater pond aquaculture. Studies of catfish pond effluents have indicated that discharge is infrequent, has little negative impact on the environment, and can be managed through best management practices (BMPs). One important difference between catfish farming and hybrid striped bass farming that affects the discharge of wastes, and potentially the impact on the surrounding environment, is that most catfish ponds are drained once every 6 to 10 years (USDA 2003), while hybrid striped bass ponds are drained annually or biennially (EPA 2002).

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Habitat effects from hybrid striped bass farming Hybrid striped bass aquaculture operations are land-based, and occur in various regions. There is no evidence that farms have been sited in ecologically sensitive areas such as wetlands or mangroves, as has been the case with other forms of aquaculture, and farms are not sited in coastal waters. Hybrid striped bass farming poses little risk of negatively impacting surrounding habitats.

Synthesis Hybrid striped bass farming poses a minor risk to the environment through pollution and habitat effects. Tank facilities, primarily represented by one large semi-recirculating system, Kent SeaTech in southern California, recycle much of their water, capture wastes, and are integrated with agriculture, thereby reducing environmental impact. Much of what is known about the impacts from pond aquaculture comes from studies of catfish pond effluents. It has been suggested that hybrid striped bass ponds have characteristics similar to those of catfish ponds; however, one major difference does exist. Unlike catfish ponds, the ponds used to raise hybrid striped bass are generally drained each year. This could potentially increase the amount of pollution that is discharged to surrounding water bodies, but to date there is no evidence of detrimental impact. Overall, the risk of pollution and habitat effects ranks as a “Low” conservation concern.

Risk of Pollution and Habitat Effects Rank:

Low Moderate High Critical

Criterion 5: Effectiveness of the Management Regime

Hybrid striped bass farming, like other forms of aquaculture in the United States, falls under a wide range of regulatory regimes. Regulation, or more specifically, over-regulation, has been identified as one of the main impediments to an expanded aquaculture industry in the United States and some have called for a clarification of agency roles and regulatory structures (Devoe 1999; Rychlak and Peel 1993). In addition to numerous state permits that are required to operate a hybrid striped bass farm, several federal agencies have some degree of oversight, including:

U.S. Department of Agriculture (USDA) According to the Aquaculture Act of 1980, the USDA has the lead role in federal aquaculture policy and is responsible for coordinating national aquaculture policy (Buck and Becker 1993). USDA’s role is primarily promotional, providing assistance to industry through research, information, and extension services.

Environmental Protection Agency (EPA) Under recently established effluent limitation guidelines, the EPA regulates discharges of wastes from aquaculture facilities (EPA 2004). EPA guidelines apply to hybrid striped bass facilities that produce at least 100,000 pounds a year, in flow-through and recirculating systems that discharge wastewater at least 30

17 Seafood Watch® Farmed Hybrid Striped Bass Report August 31, 2005

days a year. Since pond systems are exempted from this regulation, few hybrid striped bass facilities are likely covered by this regulation.

Fish and Wildlife Service (FWS) The FWS regulates the introduction and transport of fish and shellfish through the Lacey Act (Buck and Becker 1993) and assists aquaculturists with the control of fish-eating birds through the issue of depredation permits (Curtis et al. 1996).

U.S. Food and Drug Administration (FDA) The FDA Center for Veterinary Medicine is responsible for approving and monitoring the use of drugs and medicated feeds used in the aquaculture industry (Buck and Becker 1993).

The use of best management practices (BMPs) is believed to reduce the risk of environmental damage from aquaculture (Tucker et al. 2002). Pond aquaculture BMPs developed primarily for catfish farming could be applied to hybrid striped bass farming to help improve the environmental management of the industry. Tucker et al. (2002) have suggested that some relatively simple pond aquaculture management practices can reduce the environmental impacts from waste discharges, while at the same time helping improve the efficiency of pond operations. Some of their suggestions include: operate ponds for several years without draining; maintain water levels below full so that rainfall can be captured instead of causing ponds to overflow; use high quality feeds; do not exceed the assimilative capacity of ponds; provide aeration and circulation of pond water; eliminate water exchange; use wetlands to treat effluents; and use wastewater to irrigate terrestrial crops.

Synthesis Hybrid striped bass farmers must comply with numerous regulations, both at the state and federal levels. The management of the hybrid striped bass aquaculture industry can be considered to be generally effective. There are no obvious gaps in management, though, as has been pointed out by numerous individuals, clarification of regulatory requirements would be helpful. Clarification of regulations would be helpful all around, not only for outsiders who may lack an understanding of the laws and regulations that apply and the agencies involved, but also for the farmers themselves, especially new entrants into the industry. The development and implementation of BMPs appears to be one area where hybrid striped bass farming could improve its management. This is especially true for pond facilities, management of which could improve by reducing discharge frequency and implementing techniques such as the use of wastewater for irrigation of crops and the use of wetlands to filter wastes. Clearly these techniques are costly and there are presently limits to some aspects of hybrid striped bass production; for example, problems with cannibalism currently force producers to either completely drain ponds or apply a piscicide after each production cycle. It is important to note that the industry is relatively young and much research is taking place to improve production. Great advancements have already been made in the short history of the industry.

Effectiveness of Management Rank:

Highly Effective Moderately Effective Ineffective Critical

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Overall Evaluation and Seafood Recommendation

Overall, U.S. farmed hybrid striped bass ranks as a “Best Choice” according to Seafood Watch® program criteria. There are no conservation criteria that are of “High” or “Critical” conservation concern for all current production systems. For pond systems, 3 criteria are of “Low” concern, and for closed systems 4 criteria are of “Low” concern. The hybrid striped bass aquaculture industry is dependent on marine resources in feeds, but advancements in feed formulations in recent years have led to decreased dependence on wild fish for feed ingredients. There are potential risks from the escape of farmed hybrid striped bass, and caution must be taken to ensure that the environment and wild populations of fish are not negatively impacted by escapes. Different systems pose different levels of risk, with pond systems carrying a higher level of risk than closed or semi-closed systems. Overall, there is little risk of transfer or introduction of diseases and parasites from hybrid striped bass farms to wild fish and the discharge of wastes is not believed to be a major conservation concern. Management of the hybrid striped bass aquaculture industry is effective and well regulated; however, the increased development and adoption of best management practices could potentially further improve the environmental performance of the industry.

Table of Sustainability Ranks

Management Effectiveness √ (all)

Overall Seafood Recommendation:

Farmed hybrid striped bass (pond culture and tank culture):

Best Choice Good Alternative Avoid

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Acknowledgements

Seafood Watch® thanks Dr. Eric Hallerman (Virginia Tech) and Dr. Gerald Ludwig (USDA— ARS) for their helpful reviews of earlier drafts of this report. Seafood Watch® also thanks John Kilpatrick (Nebraska Game and Parks Commission), Ronald Hodson (NC SeaGrant), Delbert Gatlin (Texas A&M University), and Jim Carlberg (Kent SeaTech) for providing information that contributed to the preparation of this report.

Scientific review does not constitute an endorsement of the Seafood Watch® program, or its seafood recommendations, on the part of the reviewing scientists. Seafood Watch® is solely responsible for the conclusions reached in this report.

20 Seafood Watch® Farmed Hybrid Striped Bass Report August 31, 2005

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