Pistrin Marco

Sessione: ALLEVARE NEL FUTURO: LE NUOVE TECNOLOGIE

Ricerca in aquacultura e sostenibilità: l’aquacultura integrata multitrofica

The development of modern-day intensive aquaculture has been made possible by way of critical advancements in both technology and management practices as well as the implementation of stringent environmental regulations. The advent of “high-tech” aquaculture using an ecosystems approach, brings forward several questions and possibilities for mankind to reach new heights and provide more cost-effective means for to sustain growth of our societies, help alleviate poverty and malnutrition in rural and impoverished regions, and to impart environmental and economic sustainability in the process. These are however, unchartered territories and there are many challenges associated with being “new” and “avant-garde”. Aquaculture has been at the forefront of the growth curve for global protein production and relying on our seas, oceans, lakes, rivers, streams, and ponds to provide us with wild-caught food products has never been more of a challenge as it is today. Along with the immediate benefits such as producing food, creating jobs, and bolstering commerce, it is known that aquaculture has several serious drawbacks as well. Excessive amounts of aquacultural wastes are continually being spewed into our fresh and salt water systems. These untreated wastes are usually discharged directly into the environment, where they may enhance eutrophication, organic enrichment and turbidity of the local waterways. With the open ocean, coastal and estuarine waters, rivers, lakes, and an array of man-made water-ways all being in intimate contact with one another, subsequent cross-contaminations of these water-ways have lead to increasing incidences of disease and/or problematic feral species introductions. Aquaculture and abiding water currents facilitate the movement of substances that would have not otherwise been possible. These, along with the subsequent destruction of habitat, and the disproportionate use of fish meal, are all sited as important areas of concern amidst scientists, fishermen, environmentalists, and policy- makers alike. Enter, IMTA (Integrated Multi-Trophic Aquaculture). Assessment of the potential application of the range of possible types of IMTA (Land-Based, Sea-Based, Aquaponics, IMRAS) requires consideration of three interrelated aspects of production, socio-economics and the environment. “Multi-Trophic” refers to the incorporation of species from different trophic or nutritional levels in the same system, and with complementary resource needs, are produced in the same system. This is one potential distinction from the age-old practice of aquatic polyculture, which could simply be the co-culture of different fish species from the same trophic level. Typically, these aquaculture systems integrate the production of a fed organism, such as finfish or shrimp, with that of extractive organic aquaculture such as shellfish and extractive inorganic aquaculture of seaweed (macroalgae). IMTA is a practice in which the by-products (wastes) from one species are recycled to become inputs (fertilizers, food) for another. Feeding fish results in faeces production (nutrients) which in turn can be utilised by plants (i.e. Aquaponics) and a host of other organisms. Alternatively, the nutrients may be used to create micro-algal and zooplankton blooms which may feed other organisms that graze on these blooms.

The desired IMTA design will achieve:

1. High bioremediation efficiency in a limited space,

2. Higher growth rates of extractive organisms than in monocultures

3. Increased farm revenues.

This way, the further development of IMTA shall build upon and incorporate a host of benefits and will thus contribute towards a more sustainable and productive form of aquaculture. The development of IMTA requires the identification of environmental and economic risks and benefits of such large-scale systems, compared with similarly-scaled monocultures of high trophic-level finfish in systems. The internalizing of economic, societal and environmental costs of finfish monoculture production by the bio-remediative services of extractive species in IMTA Sea-Based and Land-Based systems, alike, continually needs to be examined and analyzed. The results of such investigations will help determine the practical value of adopting the IMTA approach as a strategy for the development of more efficient and sustainable aquaculture.