Abstract
Although aquaculture is a controversial industry, ecology dictates that wild fish are a finite resource. Increase demand for seafood has, and continues to decimate wild fisheries, necessitating the expansion of aquaculture to supplant these markets. Among all agriculturally produced meats, fish yield the best value at the lowest cost. However, in a world where commodities are growing ever scarcer, agriculturalists are competing in a global market for the raw materials required to produce livestock feeds. One of the most valuable commodities is fishmeal and fish oil which is required for optimal health and growth of farm raised fish. As costs of fishmeal have continued to sky rocket over the course of the last 20 years, aquaculturalists look to alternative resources to feed their live stock in order to keep their products competitively priced.
Background
Aquaculture feeds are pellet meals that are the staple diet of farm raised fish which are destined for the dinner table. The feed is comprised of barley, wheat, soy and DDGS (dried grains with soluble a by-product of ethanol production), which are used for their protein, carbohydrates, and lipid content. The largest dietary component of these feeds however, is fishmeal and fish oil, which yield a high proportion of protein, important omega-3 fatty acids, and enhance palatability. Feeds used in the production of swine, poultry, and beef products are also derived from these types of ingredients, including fishmeal and fish oils. Thus each of these agricultural industries is competing for the same commodities.
Pure fishmeal is an important ingredient for aquaculture feeds because it provides the nutritional components required for fast and normal growth of cultured species that are used for human consumption such as salmon, trout, tilapia, catfish, carp (very popular in China), and shrimp. Currently more than 50% of the seafood consumed globally is derived from farm raised sources (NOAA/USDA 2010). Traditionally, fishmeals that comprise the feeds provided to these cultured specimens have been resourced from wild bait fish such as pilchard, sardines, mullet, capelin, herring, and anchovies from fisheries throughout the world. These are resources which aren’t particularly abundant in North American waters with a few exceptions. Furthermore, and perhaps most importantly, nearly all of these baitfish fisheries are over exploited and many are deemed to be on the brink of collapse (Molyneaux, 2007).
Regardless, demand for seafood will rise, as fish are consumed as a luxury in some parts of the world, just as well as fish are consumed for sustenance throughout most of the rest of the world. It is estimated that more than 2 billion people rely on fish as their primary source of dietary protein. Fish are healthy foods which provide omega-3 fatty acids which are scarcely found in other natural or synthetic products. Best of all, the feed conversion ratio of fish is much greater than that of other agricultural animals (Molyneaux, 2007). The feed conversion ratio is a measurement of how much edible meat is produced per amount of feed supplied, the conversion of most fish is near 4 pounds of feed per 1 pound of fish. Other agricultural products don’t even come close, the most absurd comparison of 80:1 ratio for beef, and the best being 13:1 ratio in poultry.
Complicating matters further, feed meals are global commodities that are traded and sold to processors, wholesalers, and private resellers. Although gross national production of many of these commodities is high in the United States, much of these products are consumed throughout the North American market. Aquaculturalists must compete for ingredients against traditional agriculturalists, ethanol producers, direct grain consumption, and pet feeds. The most expensive component however, is the fishmeal that remains a staple ingredient in these compound feeds. Unfortunately the United States is a small player in the production of aquacultured products, and has suffered greatly in the global market, especially in the trade of fishmeal and fish oil (NOAA/USDA 2010).
Fortunately, cost of fishmeal, combined with an increasing national market for seafood products has spurred interest in the research and development of fishmeal alternatives derived from less volatile commodities. Currently, the alternative feeds program is still in the research and preliminary development stages, and recently there have been a number of reports released about the findings of feeds derived almost wholly from soy, rapeseed, and DDGS.
Additionally, researchers are looking at the bounty of fish processing by-products and by-catch, some of which is already used as fertilizers. It is questionable whether or not these by-products are a viable alternative because of specific metabolite problems of using bone rich fishmeal, but researchers may find a way to process the meal into a digestible alternative. The present thought is to replace whole fishmeal in aqua feeds with processed by-catch fishmeal, and increasing amounts of plant proteins.
Analysis
By-Product and By-Catch
In order to examine the feasibility of alternative feeds we must objectify the options quantitatively and qualitatively. Quantitative analysis is perhaps is of foremost importance because if fishmeal weren’t already a scarce commodity, alternatives wouldn’t be necessary, or even economically feasible. Of the 6.2-6.5 million metric tons of fishmeal produced annually, over 50% is used to produce aquafeeds, and over 85% of the 1.2 mmt of fish oil produced in the processing of fishmeal is used in aquafeeds (Hardy, 2008). To supplant this resource entirely is a daunting proposition. However, current estimations of by-product and by-catch alone are equal to the annual landings that are used to produce the current 6.5 mmt of fishmeal and 1.2 mmt of fish oil (Hardy, 2008). Thus, if by-catch and by-products were recovered we would double the amount of annual landings! The proposition of using by-catch and by-products for fishmeal production is not without obstacle however, the legality of fish by-catch as a resource, and the metabolic challenges facing animals on diets comprised of by-product need to be addressed by lawmakers, researchers and bioengineers.
By-catch is the catch of untargeted species during ocean fishing, typically dealt with by throwing hooked or netted fish (or other animals) overboard back into the ocean. This is particularly problematic for one particular reason; these animals are always dead or will die after the catch. The untargeted animal has been hooked on a long line for long hours or even days, inducing stress, and preventing respiration entirely for obligate ram ventilators such as mackerels and sharks. Fish rapidly dragged from the depths in nets bloat due to the expansion of gasses in their swim bladder, this damages internal organs and prevents the animal from diving back into the sea. It seems a real shame to fishermen to toss these animals overboard because of seasonal restrictions and laws preventing their harvest. However, allowing the capture of by-catch may lead to abuse of non-target species.
Concerning the preservation and capture of by-product fishmeal, there are both logistic and metabolic barriers to implementing effective feed production. As per metabolic barriers, the quality and composition of by-product fishmeal is significantly different from concentrated protein captured from whole fillets. Particular concern is given to the increased calcium and phosphorous constituents of by-product meal because it has high amounts of bone and cartilage. This is problematic because calcium and phosphorous are soluble in acidic environments like the stomach, but when passed into the relatively more basic environment of the intestine where absorption of nutrients actually occurs, the calcium and phosphate aggregate and fall out of dissolution. This surplus of cations concentrated in the intestinal lumen bind anions, especially zinc, and result in nutritional deficiencies (Hardy, 2008). Thus logistically, by-product must be processed in a separate fashion from whole fillet fishmeal. Consequently there must be enough by-products in quantity and continuously of which to process in order to make processing plants economical. For many localities, limited fishing seasons restricts the frequency and quantity of landings throughout the greater part of the year, and most landings are not concentrated in any specific area. This stresses the capacity of processors to build and maintain separate by-product processing plants, necessitating that seasonal whole meal processors rework existing plants to facultatively process by-product.
Plant Alternatives
The proposition of replacing fishmeal protein with plant protein feeds offer attractive cost incentives to farmers, and promising opportunities for feed developers. The protein meal alternatives include copra, cottonseed, palm kernel, peanut, rapeseed, soybeans, sunflower seed, terrestrial animal, and DDGS. The most abundant by far is soy which accounts for an annual 175 mmt, followed by rapeseed and DDGS tied for annual gross production at about 35-40 mmt each (Allen). To illustrate the cost advantage of plant derived protein feeds over fishmeal, it should be mentioned that although fishmeal trades on average only about twice as expensive as soybean meal, the soybean has traded at a relatively stable and slowly rising price of around $300/metric ton. By comparison, fishmeal trades on average near $750/mt, however the fishmeal market has been an increasingly volatile, trading as high as $2000/mt over the course of the last 5 years (Allen).
Additional consideration must be given to the fact that protein, the component of all feeds that gives rise to growth, constitutes 68% of the dry weight of fishmeal, whereas protein constitutes just 45% of the dry weight of soybean meal. Retrospective analysis yields that the market value of soybean meal then averages somewhere near $650/mt in crude protein, and fishmeal yields closer to $1100/mt respectively. This analysis still maintains a significant spread, and champions soybean protein as the economical alternative, but what about other plant derived proteins?
In terms of gross production, there are only three plant derived feeds to consider, soybean, rapeseed, and DDGS. The feed production of other crops is negligible, and the ethanol industry presents a significant barrier to harnessing corn meal as an economical alternative. However DDGS, dried distiller’s grains with solubles, is a low cost by-product from the production of ethanol, derived from spent stock of corn starch and grain sorghum. Protein in DDGS only accounts for a mere 30% of the feed, but cost on basis of crude protein is just 500/mt. Some analysts suggest that the amount of crude protein produced could be enhanced by fractionating the protein, fiber and oil prior to the distilling process.
Another promising development among plant derived feeds comes from a few small research groups suggest the culture of marine micro and macro algae as alternative sources for feed protein with the added advantage that these feeds are high in omega-3 fatty acids (NOAA/USDA, 2010). Qualitatively these studies show promising benefits of marine proteins, quantitatively, these resources are currently very small and will require much development if they are to contribute significantly as fishmeal alternatives.
Preliminary Studies
Now that we’ve established that there are quantifiable and equitable shares of plant derived protein to supplant fishmeal production, what about the qualitative, metabolic results of these feeds when used in aquaculture production? Preliminary research has been spearheaded by independent aquafarms throughout the world, as well as universities throughout the United States, including the University of North Carolina Wilmington which is home to one of the nation’s largest aquaculture laboratories. Without going into specific details, the consensus among four studies presented in a paper published by the NOAA and the U.S. Department of Agriculture was that aquafeeds must maintain some amount of fish or krill meal to remain palatable for cultured fish, and although feed conversion ratios of soy meal diets were greater than fishmeal conversion ratios, the fish in each of these studies had 10% slower growth rates compared to control groups on traditional feeds (NOAA/USDA, 2010).
Implications
Reduction of only 10% seems menial, but this represents significant logistic challenges and risks for aquaculturalists. This translates to longer turnaround time, reduces gross productivity and delays in hatchery and grow-out, and increases the input of feed, antibiotics, antiseptics, prophylactics, fuel, and electricity (Engle, 2010). Any improvements in feed conversion ratios or initial savings on feed may amount to net bust or worse, thus alternative feeds may not be enticing to established aquafarms which face recalibration in the process of converting to alternative feeds. New farms will need to take a calculative approach to make alternative feeds economical in the long run. Fortunately mass production of alternative feeds will make their use more economical for aquaculturalists.
Conclusion
While there is still much room for improvement in the formulation of plant derived feeds for aquaculture, the good news is quantitatively, the material resources are available to draw from. Some radical alternatives like algae meal may lead to development of whole new industries for entrepreneurs with true grit to expand upon. Taken together, the United States stands to gain considerably by harnessing opportunities in developing domestic aquaculture production, utilizing existing feed processing technology to supply domestic and foreign markets, and by developing new and existing agricultural resources in alternative feed production.
Based on increased demand for fishmeal over the course of the last decade, inevitably we will soon face, and in many cases already are, barriers that prevent increases of gross production from natural resources. In fact, in many fisheries annual landings are shrinking considerably. This condition will only serve to drive the cost of fishmeal and fish oil even higher, necessitating the recovery of by-catch and by-product and enhancing incentives for the exploration of alternatives. The burden will fall on everyone from small fishing vessels, feed producers, lawmakers, researchers, and independent fish farmers to make the necessary changes and developments that make the production of high quality seafood available and affordable for consumers around the world.
References
-Allen, Geoff. "Sustainable Aquaculture Feeds." NSW Government/Port Stephens Fisheries Institute. Accessed February 22, 2011. http://www.gaalliance.org/update/GOAL10/Allan.pdf.
-Engle, Carole R. Aquaculture Economics and Financing. Singapore: Wiley-Blackwell, 2010.
-Hardy, Ronald W. "USDA ARS/CSREES Aquaculture Stakeholder Workshop Fish, Feed & Nutrition." Aquaculture, March 2008, 37-40.
-Hardy, Ronald W. "Seafood Processing Waste And By-Catch: Underutilized Resources Or Lost Cause?." Aquaculture, January 2008, 37-40.
-Molyneaux, Paul. Swimming in Circles: Aquaculture and the End of Wild Oceans. New York: Thunder’s Mouth Press, 2007.
-NOAA/USDA Alternative Feeds Initiative. "The Future of Aquafeeds." Accessed February 20, 2011. http://aquaculture.noaa.gov/pdf/feeds/aquafeedsrept_nov2010.pdf.
-USDA and Foreign Agricultural Services. "Oilseeds: World Markets and Trade." Accessed February 26, 2011. http://www.fas.usda.gov/oilseeds/circular/2010/December/oilseedsfull12-10.pdf.
