8 of the growth variation in the soy-fed fish. Our next steps are to validate these markers, and to then start selecting for those adaptations. If we can select for these traits, then we could be culturing fish on soy diets that are not just comparable to fish on standard diets, but which rather show better growth rates and lower FCRs than on fishmeal-based diets. That’s the ultimate – a more sustainable, scalable diet that results in better performing fish!
AQUAFEED.COM How important is it to find alternative feeds for tunas, groupers and yellowtails? NAS Alternative feeds are key to the responsible scale-up of these species. There is great market demand for these high-value fish, but currently, they are mostly being fed with wild-sourced fish: either forage fish, trash fish or moist pellets. Part of the challenge, up to now, has been that tunas, groupers and yellowtails such as hamachi were all ‘ranched’ i.e. dependent on wild-caught fingerlings, or larger juveniles captured for fattening. These wild fish are very difficult to wean onto pellet diets. But two recent developments now offer opportunity to overcome this: Firstly, hatchery production techniques are now in hand for most of these species, meaning that they can initially be weaned in the hatchery from Artemia directly onto compound diets. Secondly, there have been tremendous advances in formulation of softer feeds, rather than the hard, extruded pellets. We have been working with Rick Barrows’ socalled “Eco-Sardine”, with very encouraging results with Yellowfin Tuna, Giant Grouper (Epinephelus lanceolatus) and
kampachi. This is a soft, squishy feed – more like fruit leather than a normal pellet. The Illinois Soybean Association has also independently developed a soft pellet diet that has tested very well with Bluefin Tuna.
AQUAFEED.COM Your company has been working on diets for herbivorous fish, such as Kyphosids. What are the underlying drivers behind this work, and what progress can you report? NAS Modern fish farming is becoming very capital-intensive. From a development perspective, that is unfortunate, as it excludes many coastal communities – particularly in less-developed countries (LDCs) – from actively sharing in the benefits of industry growth. But the biggest cost for marine fish farms is not the equipment – it’s the feed. For a wellmanaged farm, feed represents over 60% of the cost of production. At the same time, one of the primary challenges for expanded culture of seaweeds in LDCs is that the market is remote, and shipping costs are high, for a very low-value product. Most of the labor involved in seaweed production is for drying the product, to reduce these shipping costs. However, if we can develop culture methods for highly-esteemed herbivorous fish, such as kyphosids (rudderfish, or chubs), or rabbitfish, then a large part of the feed could be supplied from within the community, by local seaweed farmers. This means that more of the feed costs are spent in-country; the overall feed costs would be lower; and the fish farm could be supporting broader community employment by boosting the demand for seaweed locally.
“Part of the challenge, up to now, has been that tunas, groupers and yellowtails such as hamachi were all ‘ranched’ i.e. dependent on wild-caught fingerlings, or larger juveniles captured for fattening. These wild fish are very difficult to wean onto pellet diets.”
We have raised kyphosids in the hatchery previously, using wild-collected eggs. The challenges we currently face are identifying the most nutritious seaweed species, and obtaining reliable spawns from captive broodstock. We persevere.
AQUAFEED.COM Finally, what is the one thing you'd like to see happen in aquaculture in the next 15 years? NAS It is my fervent hope to see American chefs and consumers embracing responsibly farmed seafood, preferentially over wild caught. I want to see people choosing to eat seafood because they know that it is better for them, and better for the planet, and choosing farmed seafood over wild because they understand that it is the only way that we can sustainably scale production: because it’s the right thing to do. AFΩ