LIFE CYCLE ASSESSMENT OF CHINESE CARP POLYCULTURE SYSTEMS FROM THREE PROVINCES

Introduction

China produces is, by far, the largest producer and consumer of farmed fish in the world, including a large variety of freshwater and marine finfish, molluscs, crustaceans and plants, representing around 70% of global aquaculture production. Chinese carps (grass carp, bighead carp, crucian carp, common carp and silver carp) and tilapia are the most cultured finfish species, produced in varied polycultures, often integrated with terrestrial livestock. Although most carp are produced for domestic markets, their production relies on global supply chains with far-reaching impacts.

Production grew rapidly from the1980s and has underpinned the "Blue Revolution". However, very little is published on Chinese aquaculture production and there has been almost no publication in international literature concerning the environmental efficiency or impacts of this production. We present a comprehensive Life Cycle Assessment of Chinese carp production covering the three largest producing provinces (Hubei, Jiangsu and Guangdong) with primary data collected from over 100 farms in each province, including feed use, production intensity, energy and fuel use.

Methods

Major aquaculture producing areas within the three largest carp producing provinces were targeted for data collection with a hyndred farms surveyed in each of Hubei, Jiangsu and Guangdong. A comprehensive survey was constructed, detailing critical inputs and outputs to conduct an LCA, including aquaculture production, feed use, electricity, fuel, fertiliser and chemical use. Data was also collected from aquaculture production facilities on sustainability perceptions, stock losses, labour and costs. Feed ingredient data was also collected from two large feed producers for a standard carp polyculture and monoculture feed. Data was cleaned and classified into different scales and production types before being modelled in Simapro software. Methods followed the EU PEFCR approach wherever possible using economic allocation for feed resources and for co-produciton at the aquaculture facility. Agifootprint 7.0 and Ecoinvent 3.12 databases were used for feed and energy inputs respectively.

Results and discussion

Most farms were polycultures of several fish species, most typically with grass carp (Ctenopharyngodon Idella), silver carp (Hypophthalmichthys molitrix) and bighead carp (Hypophthalmichthys nobilis) as the most common, traditional combination. Crucian carp (Carassius carassius) was the next most cultured species, either in monoculture or as a polyculture, with far fewer farms culturing other species. However, in Guangdong, many farmers were culturing mud carp (Cirrhinus molitorella) which was used as live feed for mandarin fish (Siniperca chuatsi). There were some other impotant differences between provinces. Guangdong produced fish more intensively and farms were often larger scale compared especially to Hubei which had lower stocking rates, smaller farms and were generally more diverse (Figure 1). Feed is often by far the largest contributor to Life Cycle impacts of aquaculture production (Newton and Little 2018) and this was also the case for Chinese carp with over 90% of climate change, land and water use impacts. However, eutrophication at the farm production site was also a major issue, especially at the very intensive farms in Guangdong. Overall impacts from carp production were inline with other aquaculture species. However, much of this was related to high eFCRs (ave 2.27) and the actual impact of feed was low compared to some other aquaculture species. Therefore, impact could be reduced substantially by improving eFCR by several means. The Chinese government has been concerned with reducing the impact from aquaculture which is regarded as a major cause of eutrophication and evidence suggests that many aquaculture areas are being converted to other industries or even rewilded (Newton et al 2021), perhaps with a more conscious strategy of zonation to avoid conflicts between stakeholders.

Figure 1. Distribution of different scale aquaculture farms between 3 Chinese provinces (a) and average number of species cultured (b)

Acknowledgment

This research was funded between Monterey Bay Aquarium's Seafood Watch programme and the EU SAFE project. The SmartAqua4FuturE (SAFE) project has received funding from the European Union's Horizon Europe programme under grant agreement no. 101084549. The University of Stirling 's contribution is funded by Innovate UK through the Horizon Europe Guarantee Fund. We would also like to acknowledge the tireless work of students from Shanghai Ocean University in collecting and enumerating the data for this project.

References

NEWTON, R., ZHANG, W., XIAN, Z., MCADAM, B. & LITTLE, D. C. 2021. Intensification, regulation and diversification: The changing face of inland aquaculture in China. Ambio, 50, 1739-1756.

Newton R & Little D. (2018). Mapping the impacts of farmed Scottish salmon from a life cycle perspective. International Journal of Life Cycle Assessment. Special issue: Challenges and best practices in LCAs of seafood and other aquatic products. DOI 10.1007/s11367-017-1386-8