Life Cycle Assessment of Seabass (Dicentrarchus labrax) Produced in Offshore Fish Farms: Variability and Multiple Regression Analysis

Abstract

Equations were developed through multiple regression analysis (MRA) to explain the variability of potential environmental impacts (PEIs) estimated by life cycle assessment (LCA). The case studied refers to the production of seabass in basic offshore fish farms. Contribution analysis showed that the components of the system which most influence the potential environmental impacts are the feed (54% of the overall impact) and the fuel consumed by vessels operating in the farm (23%). Feed and fuel varied widely from one fish farm to another due to different factors, such as the efficiency of the feeding system used in each of them, or the distance from the harbor to the farm. Therefore, a number of scenarios (13) were simulated with different values of both factors and the results of the PEI were fitted by MRA to the model: PEI = a + b × Feed + c × Fuel. For all the PEIs, the regression coefficients were significant (p < 0.05) and R2 was 1. These equations allow us to estimate simply and quickly very different scenarios that reflect the reality of different farms at the present time, but also future scenarios based on the implementation of technologies that will decrease both feed and fuel consumption.

Environmental Life Cycle Assessment of Mediterranean Sea Bass and Sea Bream

“…Aubin et al [24] reported an FCR of 1.77 for sea bass rearing in Greece, while a Tunisian study reported an FCR of 1.85 and 1.88 for sea bream and sea bass, respectively [27]. Garcia et al [26] reported an FCR of 2 for sea bream production in Spain and, more recently, Garcia et al [25] reported an FCR of 1.5 to 1.9 for sea bass, depending on the growing stage. As the FCR depends on a series of environmental factors, those variations amongst studies are reasonable.…”

“…The hatching and nursing phase includes activities taking place in onshore facilities, stock maintenance and phytoplankton and zooplankton production. Given the nature of the operations and that the fish is transferred to the rearing facility when it reaches a mass of 2 g, it is reasonable to assume that the environmental impacts of the hatching and nursing phase are insignificant compared to the rearing operation, growing fish from 2 g to 600 g. Therefore, it was excluded from the product system, in line with preceding literature studies [25,26]. This assumption is further supported by the fact that a previous study focusing on rainbow trout production reported a negligible contribution of the hatchery to the life cycle climate impact and a 2% contribution to the eutrophication impact [37].…”

“…The fish rearing operation lies in the heart of the sea bass and sea bream production systems and has been examined by a series of preceding literature studies [24][25][26][27]. In this study the FCR was fixed at 2.5 for sea bream and 1.85 for sea bass.…”

“…The emissions were not partitioned between solid and dissolved fractions, as no such options exist in GaBi and Ecoinvent. Garcia et al [25] reported the emissions of N and P for sea bass production as 105.27 and 17.21 kg tonne −1 of live fish, respectively. For sea bream production, this study reports emissions 172 kg N tonne −1 of live fish and 30 kg P tonne −1 of live fish.…”

“…For the case of Mediterranean aquaculture species, Aubin et al [24] examined the production of sea bass in marine-based cages in Greece and compared them with other intensive aquaculture production systems. Garcia et al [25] performed an LCA of sea bass production in Spain, identifying the feed production and fuel consumption as the most environmental intensive processes. Similar results were reported by Garcia et al [26] for sea bream production, while Abdou et al [27] performed a comparative assessment of sea bass and sea bream, concluding that the former results in lower environmental impacts in all impact categories.…”