Gary H. Wikfors, NOAA, NMFS, Northeast Fisheries Science Center, 212 Rogers Avenue, Milford, CT 06460 USA. 

The word “sustainable” has several formal definitions, but its over-use in fisheries and aquaculture discussions has obscured meaning such that the word is invoked with little thought to what really is intended.  Everyone agrees that aquaculture needs to be “sustainable,” but how do we assess “sustainability?”  Organizationally, NEFSC has taken on this challenge by re-titling a Branch in the new Ecosystems & Aquaculture Division as the “Aquaculture Sustainability Branch,” with the assignment to assess sustainability of aquaculture practices.  In taking on this challenge, we recognize that there are several, hierarchical layers of sustainability.  First, the organism under cultivation must be sustained by the culture practice and the environment containing it.  Next, investments in infrastructure, energy, and effort must be more than compensated by the financial value of the product – the farmer must be sustained.  The layer of sustainability that we often intend – ecological sustainability – is irrelevant if the first two levels are not affirmed.  Ecological sustainability, however, lacks the clear criteria one can assign at the organism level (alive or dead) or the economic outcome (profitable or not).  Fundamentally, ecological sustainability is a social construct in that it is defined by what the human community will tolerate and permit in terms of environmental modification.  Thus, the job of aquaculture assessment science is to provide quantitative data on ecosystem interactions of aquaculture practices in the environments where they exist and, pro-actively, to develop cultivation technologies that address all levels of sustainability as humankind transitions to sourcing of seafood from cultivated fisheries.