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The Skimmer on Marine Ecosystems and Management

Aquaculture production is an increasingly important component of global seafood production. Seafood production from aquaculture has expanded nearly six-fold since 1990, while capture fisheries production has remained relatively stagnant. According to the UN Food and Agricultural Organization’s most recent analysis of global fisheries and aquaculture, seafood production from aquaculture (excluding seaweeds) exceeded production from marine capture fisheries for the first time in 2016.[i]

Aquaculture’s reputation is mixed, however. It obviously has the potential to feed many people, but it has is associated with a number of observed and potential negative environmental impacts, including:

  • Altering and destroying habitat, such as mangrove forests, for aquaculture facilities
  • Escapes of farmed species into the wild, enabling species invasions and altering the genetics of wild populations
  • Spreading diseases and parasites to wild populations
  • Releasing fecal waste, uneaten food, and pesticides into the local environment, decreasing water quality
  • Contributing to the overfishing of wild fish populations because of the use of wild fish to feed farmed fish.

This negative view obscures the incredible diversity of aquaculture types and their diverse interactions with marine environments. Aquaculture enterprises vary in:

  • What species are cultivated (e.g., seaweeds, mollusks, crustaceans, finfish) and what they feed on (e.g., whether they are photosynthesizers, filter feeders, deposit feeders, herbivores, carnivores)
  • How intense production is (e.g., total biomass per cage, the degree to which fertilizer and supplementary feeds are used)
  • The type of environment production takes place in (e.g., freshwater streams or lakes, fully enclosed tanks, ponds, intertidal, sheltered bays, open ocean, sea pens, ponds, tanks).
The Skimmer on Marine Ecosystems and Management
The Skimmer on Marine Ecosystems and Management

Editor’s note: Thierry Chopin is a professor of marine biology and director of the Seaweed and Integrated Multi-Trophic Aquaculture Research Laboratory at the University of New Brunswick in Canada. He is also president of Chopin Coastal Health Solutions Inc. His research focuses on the ecophysiology/biochemistry/cultivation of seaweeds and the development of Integrated Multi-Trophic Aquaculture (IMTA) for environmental sustainability, economic stability, and societal acceptability.

The Skimmer: Can you tell us a little bit about what IMTA is?

Chopin: With IMTA, farmers cultivate species from different trophic levels and with complementary ecosystem functions in proximity. They combine fed species (e.g., finfish that need to be provided with feed) with extractive species (e.g., seaweeds, aquatic plants, shellfish, and other invertebrates that extract their food from the environment) to take advantage of synergistic interactions among them. In these systems, biomitigation operates as part of a circular economy (i.e., nutrients are no longer considered wastes or by-products of one species, but instead are co-products for the other species).

The Skimmer on Marine Ecosystems and Management

By Tundi Agardy, Contributing Editor, The Skimmer. Email: tundiagardy [at] earthlink.net

A recent publication “Marine zoning revisiting: How decades of zoning the Great Barrier Reef has evolved an effective spatial planning approach for marine ecosystem-based management” published in Aquatic Conservation: Marine and Freshwater Ecosystems distills important lessons from Australia’s evolving commitment to manage the world’s most iconic multiple use marine protected area. It casts a critical eye on what has worked and what has not, and it pushes us beyond our marine comfort zone to face the challenge of true ecosystem-based management (EBM), which neither ocean zoning nor marine spatial planning (MSP) in their current applications can adequately provide. With this publication, Jon Day and his coauthors have given the world a valuable gift that will keep on giving if we can acknowledge this gift and heed it.

Day and his colleagues (including Richard Kenchington, who like Day has been intimately involved in the design and management of the Great Barrier Reef Marine Park [GBRMP] through its various iterations over the years) recount how zoning both set the stage for multiple use management and evolved to provide the legal framework for regulations to protect the world’s largest barrier reef. The use of zoning had to be adapted over decades because the GBRMP Authority was a pioneer in spatial management and the allocation of space to uses of the marine environment. Zoning on land may have provided a glimpse of the possible, but adapting zoning approaches to the fluid and obscured ocean realm required experimentation and a fair amount of risk taking.

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