Changes in Attitudes Are Needed

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There is a paradoxical situation when looking at current worldwide food production. In agriculture, 80% of the production is made up of plants and 20% of animal products (meat, milk, eggs, etc.), while in aquaculture, 80% of the production is animal biomass and 20% is plant biomass. Considering only mariculture, the world wide production is made up of 45.9% seaweeds, 43% mollusks, 8.9% finfish, 1.8% crustaceans, and 0.4% of varied other animals. Consequently, in many parts of the world, aquaculture is not synonymous to finfish aquacul ture, as so many people in affluent western countries believe. If one is reasonably assessing, based on the need for balancing the cultured species functions within the surrounding ecosystem functions, marine herbivores, car nivores, and omnivores cannot be cultivated while neglecting marine plants - as efficient biofilters, a crop on their own, or a food component for other organisms - a fact apparently missed by a certain number of the 'Blue Revolution' proponents. Several species of seaweeds cul tivated under the right conditions, especially near sources of high levels of nitrogen as in proximity to finfish farms, can be excellent sources of proteins, important amino acids, and unsaturated oils. We need to be aware of the other food production systems in the rest of the world if we want to understand our present prevailing system and correctly position it in perspective with other systems. Seaweeds and microalgivores represent 59% of the world aquaculture production, followed by the production of 30% of omnivores and detritivores. In tonnage, the three leading aquacultured species are the seaweed Laminaria japonica, and two microalgivores, the Pacific cupped oyster, Crassostrea gigas, and the silver carp, Hypophthalmichthys molitrix. Vocal public opposition to aquaculture has been generated by 'high value' salmonids and other carnivorous marine fish and shrimp, which, in fact, represent only 11% of the world aquaculture production.

From the above numbers for mariculture, one may be inclined to think that at the world level, the two types of aquaculture, fed and extractive, are relatively balanced. However, because of the predominantly monoculture approach, these different types of aquaculture production are often geographically separate, and, consequently, rarely balance each other out on the local or regional scale. For example, in Eastern Canada, fed salmon aquaculture is presently located in the Bay of Fundy in southern New Brunswick, while extractive mussel and oyster aquaculture is located in the Northumberland Strait and the Lower Gulf of St. Lawrence, along the coastlines of Prince Edward Island and northeastern New Brunswick. In Japan, aqua culture is mostly carried out with various bays dedicated to either shellfish, seaweed, or finfish aquaculture. An inter esting situation has emerged in southern Chile with the recent development ofmussel (Mytilus chilensis) cultivation. Mussel long lines can be found between salmon cages in channels and fjords; however, the decisions regarding siting were not based on scientific data for prevailing currents, suspended matter and nutrient circulation, oxygen avail ability, etc., and the IMTA concept was not explicitly considered. There are, however, examples in China of bays managed according to the IMTA approach.

It is also important to consider that while fish do generally have a higher price per unit value (but not necessarily at a higher return on investment), sustainable ecosystems are not based on the price/value of the return to humans, but on a balance of biomass between organ isms having different complementary functions and a

Integrated multitrophic aquaculture (IMTA)

Fed aquaculture Extractive aquaculture

(Finfish) + Organic Inorganic

(Shellfish) (Seaweed)

Fed aquaculture Extractive aquaculture

(Finfish) + Organic Inorganic

(Shellfish) (Seaweed)

Figure 1 Conceptual diagram of an integrated multitrophic aquaculture (IMTA) operation including the combination of fed aquaculture (e.g,. finfish) with organic extractive aquaculture (e.g., shellfish), taking advantage of the enrichment in particulate organic matter (POM), and inorganic extractive aquaculture (e.g., seaweeds), taking advantage of the enrichment in dissolved inorganic nutrients (DIN).

balance of energy flows. One can wonder if the needed evolution (not revolution, which often takes you back to the starting point as its etymology indicates!) in aquacul ture practices is more a conceptual question of rethinking how food production systems should work more than a technological question. In other words, how to make the 'Blue Revolution' greener.. .?! It would also be appropri ate to ask the question ''Blue Revolution, but for whom.?'' Depending on the answer, different species and different systems should be focused on.

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