Frontiers in Marine Science (Jun 2014)
Strategies to enhance the competitiveness of semi-intensive aquaculture systems in costal earth ponds: the organic aquaculture approach
Abstract
Earthen ponds are the main production system for European seabass (Dicentrarchus labrax) and gilthead seabream (Sparus aurata) in Portugal and in Southern Spain. Production costs in this low productivity farming system are higher compared to intensive cage farms, and its economic sustainability depends on product differentiation and optimization of production. The development of new farming protocols, to enhance productivity of ponds and lagoons, or the implementation of certification processes to add value to products from extensive and semi-intensive systems, could render these activities more economics benefits and be attractive for a new generation of farmers. One clear strategy to differentiate and add value to seabream produced in semi-intensive systems is its production under organic standards. Feeds often represent 40-60% of the operational costs of fish farming. In relation to the traditional feeds, the organic certified feeds currently present a price-differential of about +30%. To assess it economic feasibility, it is therefore essential to validate if such higher feeding costs will represent an increase on productivity (fish growth and feed conversion) or can be fully integrated in the final sale price. Throughout a full production cycle of gilthead seabream (from 9 grams until >350 grams), a series of trials allowed us to assess the effects of: a) an organic certified feed; b) variable feeding levels (100 and 80% of recommendations); and c) culture density (0.5 and 1.0 kg/m3) on the overall growth performance, body composition and environmental impact at the fish farm level. Results show that growth performance (weight gain and feed conversion ratio) of seabream fed the organic feed was similar to that found in fish fed a traditional diet. With the organic feed, a reduction of the feeding level by 20% of the manufacturer recommendations led to a lower growth, while a similar reduction on the feeding level of the traditional feed had no impact on the performance of seabream. Lower culture density (0.5 kg/m3) resulted in higher overall growth performance. The impact, in terms of nitrogenous (N) and phosphorus (P) loads, among the various scenarios were calculated and clearly reinforce the environmental sustainability of these semi-intensive production systems. The use of organic feeds does not lead to a significant enhancement of the growth performance. Therefore, the additional costs associated to feeding under organic standards, need to be incorporated in the sale price, thus requiring a targeted and differentiated marketing and distribution approach. Sociedade Piscicultura Farense Lda, as other traditional aquacultures depends on the enhancement of the natural environment, combined with production fine-tuning and product positioning, rewarding the quality of the final product. The positive effects of extensive and semi-intensive aquaculture in coastal areas, including environmental protection and restoration in areas of particular ecological interest, employment opportunity and development in rural and coastal areas are highly appealing concepts for the general community, particularly to conscious consumers.
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