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The Skimmer on Marine Ecosystems and Management

It’s no secret that news about the ocean is pretty disheartening these days. So, as we get started with 2020, we here at The Skimmer want to highlight a new report that looks at ocean potential. The High Level Panel for a Sustainable Ocean Economy recently released “The Ocean as a Solution for Climate Change: Five Opportunities for Action”, which quantifies contributions that ocean-based mitigation strategies can make in reducing global greenhouse gas emissions, while also delivering other ecosystem services. The report considers the potential contributions of:

  • Scaling up ocean-based renewable energy (e.g., wind, wave, and tidal power)
  • Reducing emissions from freight and passenger shipping
  • Increasing protection and restoration of coastal and marine ecosystems (particularly “blue carbon” habitats such as mangroves, tidal marshes, and seagrasses), which would provide carbon mitigation as well as other ecosystem service benefits
  • Shifting diets towards low-carbon sources of protein from the ocean
  • Storing carbon in the seabed.
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).

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