Effect of production quotas on economic and environmental values of growth rate and feed efficiency in sea cage fish farming.

M Besson,M Vandeputte,E Quillet,I J M De Boer,H Komen,J A M Van Arendonk,J Aubin,Peng Xu

doi:10.1371/journal.pone.0173131

Abstract

In sea cage fish farming, production quotas aim to constrain the impact of fish farming on the surrounding ecosystem. It is unknown how these quotas affect economic profitability and environmental impact of genetic improvement. We combined bioeconomic modelling with life cycle assessment (LCA) to calculate the economic (EV) and environmental (ENV) values of thermal growth coefficient (TGC) and feed conversion ratio (FCR) of sea bass reared in sea cages, given four types of quota commonly used in Europe: annual production (Qprod), annual feed distributed (Qannual_feed), standing stock (Qstock), and daily feed distributed (Qdaily_feed). ENV were calculated for LCA impact categories climate change, eutrophication and acidification. ENV were expressed per ton of fish produced per year (ENV(fish)) and per farm per year (ENV(farm)). Results show that irrespective of quota used, EV of FCR as well as ENV(fish) and ENV(farm) were always positive, meaning that improving FCR increased profit and decreased environmental impacts. However, the EV and the ENV(fish) of TGC were positive only when quota was Qstock or Qdaily_feed. Moreover, the ENV(farm) of TGC was negative in Qstock and Qdaily_feed quotas, meaning that improving TGC increased the environmental impact of the farm. We conclude that Qstock quota and Qdaily_feed quota are economically favorable to a genetic improvement of TGC, a major trait for farmers. However, improving TGC increases the environmental impact of the farm. Improving FCR represents a good opportunity to balance out this increase but more information on its genetic background is needed to develop breeding programs improving FCR.

Highlights

The production of fish in sea cages releases, without being filtered, nutrients to the surrounding environment
When the quota was on annual production (Qprod), higher batch rotation was balanced by lower stocking density to comply with the quota
When the quota was on daily standing stock (Qstock) or daily feed distributed (Qdaily_feed), increasing thermal growth coefficient (TGC) led to more batches, but without a proportional decrease in stocking density

Summary

Introduction

The production of fish in sea cages releases, without being filtered, nutrients to the surrounding environment. Economic and environmental values in sea cage farming benthos may cause eutrophication, which affects the natural ecosystem [1, 2]. In all European countries, producing fish in sea cages has to comply with regulatory measures to limit the environmental impact. These measures require an environmental impact study of biotic and abiotic change3s due to the farming process [3, 4]. The aim of this environment impact study is to explore how much fish can be produced based on the carrying capacity of the natural ecosystem. The main goal of these quotas is to limit the environmental impact of the farm to an acceptable level

Objectives

Methods

Results

Discussion

Conclusion