Shrimp consumption has been forecast to grow ~11% by 2030. Understandably, such market expansion will have to be matched by growth in shrimp feed production. At present, shrimp feeds account for around 31% of the global supply of fishmeal (FM) while shrimp only represent 5.6% of total aquaculture harvest. This clearly unsustainable position is buoyed by heavy market demand. To service the forecast 11% increase in farmed shrimp production, an additional 3% of global FM supply would be required if current feed types are retained. Abandoning reliance on FM will demand use of alternative feedstuffs that do not negatively impact shrimp production. In fact, many laboratory trials have proven that exchange of FM with alternative proteins has no, or only limited effect, on shrimp performance. These studies thereby provide strong argument for a radical redesign of shrimp feeds to enhance sustainability. However, before such reform can be more seriously contemplated, commercial style trials of alternative diets must be undertaken. At present, these remain pauce. Accordingly, we assessed differences in growth, survival and profitability of shrimp grown in ponds using a commercial (Grobest) or open-source, fishmeal- and fish oil-free (F3) diet.
Shrimp (Litopenaeus vannamei) were stocked into four circular plastic-lined ponds of 800 m3 capacity at 150 PL m3 (120,000 pond-1). Ponds were then randomly assigned a diet (n=2) which was fed by hand or automatic feeder for 8 weeks. At trial end animals were assessed for growth, feed consumption, survival, and color post-cooking. After 8 weeks there were no differences in pond survival and shrimp fed the Grobest feed were smaller (18.03±1.73 g) than those fed the F3 diet (23.25±1.92 g; P < 0.05) with SGRs of 6.63±0.02 and 7.09±0.07% day-1 and final harvest weights of 1293.00±318.20 kg and 1502.00±282.84 kg respectively. FCRs of 1.15±0.00 and 1.03±0.01 (P < 0.05) were attained for the Grobest and F3 ponds in that order. Irrespective of diet, shrimp presented as a typical brown-grey color at harvest. After cooking, however, differences in flesh color, as assessed by SalmoFan, were apparent, with shrimp fed the F3 diet having stronger pigmentation, with a typical dorsal to ventral paling.
This study demonstrates that total replacement of dietary FM/FO in Pacific whiteleg shrimp feeds is a realistic proposition. Moreover, at trial termination an economic analysis was undertaken and revealed that return on investment for the Grobest fed ponds was 50.16%, while that for the F3 feed was 72.77%. This begs the question – why are shrimp feed manufacturers still employing FM in their diets?