By C. Greg Lutz
It seems to me that one of the great advantages of aquaculture is that Mother Nature has given us many inherent efficiencies. The very fact that most of the species we work with can convert feedstuffs into edible protein (delicious edible protein, mind you) is just part of the picture. As pointed out by our guest columnists Dr. Claude Boyd and Aaron McNevin, aquaculture’s carbon dioxide emission footprint is approximately half that for beef (per kg whole body weight), and on average aquaculture currently produces about 2.04 metric tons per hectare of land while traditional animal industries weigh in at a mere 0.23 metric tons. Fish and crustaceans don’t need to spend a lot of energy or nutrients fighting gravity… and mollusks really have that issue under control.
But there are other natural advantages available to our industry that we are only beginning to apply. Beneficial microbes can be a powerful tool to combat diseases. We still have a long way to go toward understanding the microscopic battlefields on and within the species we cultivate, and in the culture environments that surround them.
By-catch and processing wastes can go a long way to satisfy aquaculture’s need for fish meal, and fish oil for that matter. Alternative sources of protein are being developed at a rapid pace. Things like insects and single-cell protein sources are poised to solve (at least partially) many of the problems associated with the current dependency on wild fish in some aquaculture diets. And some commercial salmon operations have already reached the goal of becoming net producers of fish protein, in spite of working with a singularly carnivorous animal. Mind you we are talking about a species that, in the wild, would consume roughly 10 kg of wild fish for every kg of weight gain. So, from my point of view, even those farms where salmon still consume 4-6 kg of wild fish equivalent per kg of gain should be getting a pat on the back for that level of improvement - rather than criticism.
And speaking of alternative sources of protein, the strategy of using bio-floc production systems continues to gain ground, albeit bio-floc only makes sense within certain types of facilities and for certain species. Much of the work developing bio-floc strategies for shrimp production has taken place at facilities operated by Texas A&M University, as an outgrowth of the pioneering shrimp culture research conducted there over the years. Unfortunately, that program has come to a sudden, somewhat unexpected end. Dr. Granvil Treece provides us with an overview of the program’s history, and it serves as a cautionary note to remind us of the necessity for academic support if our industry is going to continue expanding in a profitable way.
Mother Nature can also cause serious problems for us. Bacteria naturally exchange genes, but in the case of the dreaded shrimp disease EMS this seems to have resulted in grave problems for growers on both sides of the Pacific. Granted, as an industry we sometimes push Mother Nature too far, and eventually She goes off on us. Also, there are times when She goes off for no apparent reason, with disastrous consequences. We have examples of both situations in our Latin American Report.
And, as always, questions of policy (trade, conservation, fiscal), laws & treaties, and attitudes (for want of a better word) influence every aspect of what we do. We consider some of these in this issue. And our columnists once again provide us with great perspective on what works, what doesn’t, and why.
Write us any time – we are interested in your ideas for articles, site visits, program reviews, new topics, etc. After all, this magazine is written for you. Editorinchief@dpinternationalinc.com
Dr. C. Greg Lutz has a B.A. in Biology and Spanish by the Earlham College at Richmond, Indiana, a M.S. in Fisheries and a Ph.D. in Wildlife and Fisheries Science by the Louisiana State University. His interests include recirculating system technology and population dynamics, quantitative genetics and multivariate analyses and the use of web based technology for result-demonstration methods.