24 DECEMBER 2023 • WORLD AQUACULTURE • WWW.WAS.ORG Moving indoors & optimizing rearing conditions At present most intensive farming operations for fed-finfish species are conducted in open public-water bodies (including lakes, reservoirs, rivers, coastal areas) within intensive net-cage farming operations with little or no environmental control possible. As a direct consequence, these operations are often subject to difficulties of maintaining farm biosecurity and frequent disease outbreaks, fish escapes, local pollution impacts, possible animal predation, and potential conflicts with other users (water authorities, fishermen, tourism, etc.). As such, they usually suffer from a poor public perception by the media and general public. A similar situation also exists with most pond-based farming operations for freshwater and marine crustaceans, including most extensive, semi-intensive and intensive brackish-water shrimp farming operations (Figure 6). In view of the above, there has been a significant move away from the use of outdoor open cage/pond-based farming systems toward the development and use of indoor clear-water and/or floc-based (depending upon the target species) Recirculating Aquaculture Systems (RAS) where strict controls can be placed on optimizing environmental rearing conditions, including water quality, farm biosecurity, minimizing animal stress, and maximizing animal growth and feed efficiency 24/7 (Aich et al. 2020; Motta et al. 2022) (Figure 7). Improved genetics & sustainable aquaculture feeds It is generally believed that improved genetics and nutrition are keys to the future economic success and long-term sustainability of the finfish and crustacean aquaculture sectors, either through the use of improved breeding technologies and use of genetic tools (gene editing, CRISPR, genomics, transgenic fish) or the reduced dependence of the feed manufacturing sector upon the use of potentially food-grade feed inputs while maximizing the utilization of locally available feed-grade agricultural by-products and waste streams (Houston et al. 2020; Song et al. 2023; Tacon et al. 2021) (Figure 8). Expansion of seaweed & extractive species production In marked contrast to most farmed fish and crustacean species, the production of seaweeds and filter-feeding bivalve mollusks is not dependent upon the external supply of compound feed inputs. These species accounted for over 42% of total global aquaculture production in 2021 (Figure 2) and are dependent upon the supply of nutrients dissolved in the water column or through water filtration of phytoplankton and zooplankton (Chopin & Tacon 2020). Since the majority of these species are produced within open marine ecosystems, they hold particular promise for increased production within integrated multi-trophic aquaculture systems (IMTA) through their ability to harness available nutrient streams produced from marine floating net fish-pen operations (Chopin & Tacon 2020) (Figure 9). Expansion of Off-shore aquaculture In contrast to land-based farming operations, in the long run it FIGURE 7. The future – full biosecurity, environmental and stress control 24/7. FIGURE 8. Sustainable Aquaculture Feeds – replacement options and approaches. FIGURE 9. Expansion of seaweeds and extractive species aquaculture production, including use of integrated multi-trophic aquaculture (IMTA) systems. FIGURE 10. Development and expansion of large-scale off-shore aquaculture operations for the mass production of higher-value fish & crustacean species, including use of giant sea-cages, floating platforms, tankers & boats.
RkJQdWJsaXNoZXIy MjExNDY=