Opinion paper: prospects for the fed-aquaculture sector.

Since the 1970s, global demand for fish has kept increasing, particularly in developing countries where population and income growth constitute the main drivers of the rise in world fish consumption. Although output from capture fisheries stagnates, total production of fish continues to rise, thanks to aquaculture. In 2010, aquaculture contributed up to 47% of world food fish production against 9% in 1980. The optimistic view is that aquaculture is going to replace – at least partially – open sea fishing, helping to make fisheries sustainable and providing food security to many developing countries. However, there are concerns that the ecological and socio-economic impacts of aquaculture jeopardize its own sustainability. In particular, open water aquaculture is a polluting industry, that spills effluents (feeds including fertilizers, feces or chemicals) into the wild. Besides, aquaculture increasingly faces problems of space and feed scarcity. The favored locations for farms are coastal areas, where the likelihood of interfering with other human activities is high (fishing, mining, tourism, etc.). Fish feed is probably the most controversial aspect of the aquaculture production process. Aquaculture relies on fish protein for the feeding of an important share of its production. In 2008, fed-aquaculture contributed to 81.2% of global farmed fish and crustacean production (Food and Agriculture Organization, 2012). Fish meal and fish oil are key ingredients in aquaculture feed. They are made from small oily fish belonging to low-trophic levels (LTL) for about 80% and waste from processed fish for 20%. The FIFO (fish in–fish out) ratio gives the number of tons of wild fish used to produce 1 ton of farmed fish. The overall FIFO ratio was estimated to be close to 0.7 in 2006. At the carnivorous species-group level the FIFO ratio varies quite a lot between surveys, but is clearly >1. For instance, Tacon and Metian (2008) and Naylor et al. (2009) on the one hand, and the International Fishmeal and Fish Oil Organization on the other reported a salmon FIFO ratio of 4.9 and 2.2, respectively. The expansion of aquaculture urges to find substitutes to fish meal and fish oil. Some plant and terrestrial animal by-product nutrients are sources of high-quality proteins, but do not present all the properties allowing to maintain the flesh quality of carnivorous species. In our paper ‘Is aquaculture really an option?’ (Regnier and Schubert, 2013), we develop a theoretical framework to investigate the impact of the introduction of aquaculture on fish consumption, consumer utility and wild fish stocks, taking into account the sector’s dependence on feed fish and consumer preferences. The theoretical model (see Figure 1) consists of two wild fish stocks in open access and a competitive aquaculture sector. Although the general trend of tightening regulations goes against the assumption of open access, resource management schemes are far from being implemented or efficient worldwide, and this assumption seems reasonable as a benchmark. The wild species 1 is harvested for direct human consumption, whereas the other one (species 3) is used to feed farmed fish. Biological interactions of the predator–prey type take place between the two wild species: the withdrawal of the prey species 3 affects the abundance of the predator species 1, which is higher in the food chain. Consumers may choose to consume wild or farmed fish, which are assumed to be strong substitutes, according to their preferences. Finally, market interactions refer to the competition between farmed and wild fish products on the fish counter, and the resulting prices of both products. We find that the long-run impacts of the aquaculture entry are conditional on the degree of dependence of the wild edible species on the feed fish stock, and on the level of consumer spending on fish. When biological interactions are moderate and consumer spending remains below a certain threshold, the introduction of aquaculture is of benefit to consumers, whose utility increases. By providing an alternative source of food fish, aquaculture makes the price of the wild product decrease. Fishing effort decreases, allowing the edible stock to recover despite the fact that aquaculture exploits the prey species as an input. In contrast, when biological interactions are high, the introduction of aquaculture leads to a decline in the two wild fish stocks, a decrease in wild edible fish supply and an increase in its price. At high levels of consumer spending, it First published online 2 March 2015