The shrimp feed sustainability conundrum: Substituting fishmeal with plant ingredients by Wesley Malcorps, PhD student, The Institute of Aquaculture, University of Stirling, UK and Björn Kok, MatureDevelopment BV, The Netherlands
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urrently, more than 50 percent of shrimp supply originates from aquaculture. The shrimp industry is one of the dominant consumers of fishmeal in the aquaculture sector. However, in order to meet the demand for a growing industry in the face of a finite supply of marine ingredients, feed manufacturers have decreased the inclusion of fishmeal in commercial diets. In 2000, 19-40 percent fishmeal was included in shrimp feed, however, that fell to 11-23 percent in 2014. Over the years, and in response to fishmeal price increases, fishmeal has been increasingly substituted by plant ingredients. This approach is widely recognised as being more environmentally friendly due to the reduced pressure on the marine environment. However, substituting fishmeal in aquaculture feeds with plant ingredients may not be as beneficial for the environment as many people think, according to a new study. This research was conducted by an international and multidisciplinary team of experts and academics from the aquaculture industry and beyond, including; MatureDevelopment BV (The Netherlands); Institute of Aquaculture, University of Stirling (UK); Research Institute for Agriculture, Fisheries and Food (Belgium); Mexico Aquaculture Research Inc (Mexico); Association of International Seafood Professionals (Australia); Aquaculture without Frontiers (USA); Universidad Tecnológica del Mar de Tamaulipas (Mexico); IFFO, The Marine Ingredients Organisation (UK); Utrecht University (The Netherlands); University of Zürich (Switzerland); and Harper Adams University (UK). The study assessed the impact on marine and terrestrial
resources, such as fish, land, freshwater, nitrogen and phosphorus by modelling incremental fishmeal substitution, from 20-30 percent to zero, by plant ingredients. This includes ingredients, such as soybean meal concentrate, rapeseed meal concentrate, pea protein concentrate and corn gluten meal, commonly included in modern shrimp feeds for the two main shrimp species produced globally, whiteleg shrimp (Litopenaeus vannamei) and black tiger shrimp (Penaeus monodon). The results show that complete fishmeal substitution by plant ingredients could lead to an increasing demand for freshwater (up to 63 percent), land (up to 81 percent), and phosphorus (up to 83 percent). These are significant increases, as only a share of 20–30 percent of the feed is actually substituted. This is mainly caused by the inclusion of resource-intensive crops and their derived ingredients to meet nutritional requirements, such as soybean meal concentrate, rapeseed meal concentrate and pea protein concentrate. These ingredients caused a considerable rise in freshwater, land and phosphorus use. However, nitrogen demand remained relatively stable in most scenario’s, which is caused by crops requiring little to no nitrogen fertiliser, due to their ability to fix nitrogen from the atmosphere. Nevertheless, some of these crops use relatively more phosphorus, explaining the increase in demand of this valuable resource, already heavily strained under existing agricultural demand.
Complex dietary requirements
Additionally, it must be noted that complete substitution of fishmeal and fish oil with plant-based ingredients, without affecting shrimp performance, is very difficult. This is caused by the complex dietary requirements of shrimp
24 | May 2019 - International Aquafeed