Comparative environmental performance of artisanal and commercial feed use in Peruvian freshwater aquaculture

Highlights

• Substitution of artisanal feeds with commercial ones increases environmental impacts.

• Higher impacts are due to highly refined, energy-intensive feed inputs.

• Sourcing of agricultural feed inputs affects environmental performance of feeds.

• Prime instead of residual fishmeal should be used for artisanal feeds.

• Black pacu aquaculture has better environmental performance than other species.

Abstract

We used Life Cycle Assessment (LCA) to evaluate some of the environmental implications of using commercial versus artisanal feeds in Peruvian freshwater aquaculture of trout (Oncorhynchus mykiss), tilapia (Oreochromis spp.) and black pacu (Colossoma macropomum). Several scenarios believed to be representative of current Peruvian aquaculture practices were modelled, namely: production of trout in Andean lake cages; and culture of black pacu and tilapia in Amazonian and coastal lowland ponds, respectively. In general, Peruvian aquaculture is characterised by low technological intensity practices. Use of commercial aquafeeds is widespread, but artisanal feeds are frequently used in certain small-scale farms.

We found that trout feeds feature higher environmental burdens than do black pacu and tilapia feeds. A similar trend is observed for production of these species. Across species, the substitution of artisanal with commercial feeds, despite improving feed conversion ratios in all cases, does not always reduce overall environmental impacts. This is due to the additional energy use and transportation requirements associated with commercial feed inputs. The substitution of artisanal feeds with commercial ones generally increases environmental impacts of the fish farming systems for the specific feeds considered, despite enhanced FCRs and economies of scale. This is due to the higher environmental impacts associated to certain feed inputs used in commercial feeds, in particular highly refined feed inputs. Consequently, in light of the importance of feeds to overall life cycle impacts of aquaculture production, the Peruvian aquafeed industry should preferentially source less refined and, in general, less environmentally burdened feed inputs (e.g. Bolivian soybean products over Brazilian, high quality over lower quality fishmeal, avoiding protein concentrates, etc.), to the extent that fish farming performance (i.e. feed conversion efficiency and cost structure) is not strongly affected. Among species, black pacu aquaculture shows the best environmental performance.

Introduction

Aquaculture is a globally important food production sector. Worldwide, 59.9 million tonnes of cultured fish, crustaceans, molluscs and other aquatic animals for human consumption, representing USD 119 billion in economic value, were produced in 2010 (SOFIA, 2012). In contrast to stagnation in fisheries landings, aquaculture production has grown, on average, 8.8% per year since the 1980s (SOFIA, 2010, SOFIA, 2012). Freshwater species, largely carps, account for close to 60% of production (SOFIA, 2010).

Feed provision is often considered to be a critical constraint in further expansion of the aquaculture sector (New and Wijkström, 2002) although this issue is highly debated (Asche and Tveterås, 2004, Tacon and Metian, 2008a, Tacon et al., 2011). Only 30% of cultured seafood is currently produced without feed (bivalves) or with limited feed inputs (extensive aquaculture of herbivorous fish species like cyprinids), compared to 50% in 1980 (Chiu et al., 2013, SOFIA, 2012). Moreover, the proportion of fed aquaculture continues to increase as a result of both consumer preference for higher trophic level species and producer preference for the higher growth rates achieved in fed aquaculture systems (SOFIA, 2012).

Availability of fishmeal and oil (FMFO) is of particular concern with respect to ongoing global expansion of fed aquaculture. Despite that inclusion rates of FMFO have declined over time for salmonids and shrimps due to increasing use of alternative protein sources (Welch et al., 2010), overall demand has remained relatively constant due to increased use in the production of omnivorous and herbivorous species (Chiu et al., 2013, Naylor et al., 2009, SOFIA, 2012).

Previous research has shown that feed provision accounts for a large fraction of many of the environmental impacts associated with aquaculture supply chains (Henriksson et al., 2012). For instance, several publications highlight the contribution of feeds to overall impacts and specific environmental impact categories (Aubin et al., 2009, Boissy et al., 2011, Cao et al., 2011, Ellingsen and Aanondsen, 2006, Mungkung et al., 2013, Pelletier et al., 2009).

Peruvian aquaculture has grown at an average rate of 30% over the past 20 years. As shown in Fig. 1, production is dominated by marine species (scallops and shrimps, accounting respectively for 50% and 23% of all production), as well as freshwater species such as trout (Oncorhynchus mykiss; 22%), red tilapia (Oreochromis spp.; 3%) and, more recently, black pacu¹ (Colossoma macropomum; 1%) (Mendoza, 2013, PRODUCE, 2009). Other than scallops, production of these species is reliant on exogenous feed inputs. Both artisanal and commercial feeds are used, but the use of commercial feeds is preferred when economically viable for cultured fish producers, especially in the case of trout, mainly because of improved feed conversion ratios (technical feed conversion ratio — FCR, defined as the total feed distributed divided by biomass weight gain). In other words, Peruvian fish farmers usually apply either one or a combination of the following two feeding strategies: one is based on low cost (low value) artisanal feed with limited rearing performance, and the other is based on higher value industrial (commercial) feed with expected better rearing performances. These two strategies and the degree of overlap between them are dependent on the available operational budget of the farmer and the level of technical control over the production cycle.

This paper focuses on the environmental performance of aquaculture, with specific attention to the role of feed provision, for rainbow trout, tilapia and black pacu production in Peru. We developed full Life Cycle Assessment (LCA; ILCD, 2010) models for trout and black pacu production systems. In order to complete an overview of the three main cultured species in the Peruvian freshwater aquaculture sector, tilapia production was also modelled using a screening-level LCA (Wenzel, 1998). We assessed the environmental performance of various types of aquaculture systems of the three above-mentioned species, at farm gate, in order to compare their environmental performance. This was achieved by taking into account the use of either commercial or artisanal feeds and feed formulations. Feeds were also compared directly, at mill gate, in order to gauge their relative environmental performance without considering feed conversion ratios.

The results of this analysis are intended to inform both aquafeed and cultured fish producers as to the relative environmental performance of feed and fish production for alterative species and feeds. A presupposition of this study was that simpler feeds would perform better than more complex ones, when compared in isolation, on a per tonne basis. An a priori supporting argument was that certain feed inputs, especially those featuring more energy-intensive processing stages would feature higher environmental impacts than less processed crop-derived feed inputs. Typical feed inputs of the former type are wet-milling or higher levels of animal- and fish-derived inputs such as fishmeal, fish oil and animal meat.