World Aquaculture March 2019

28 MARCH 2019 • WORLD AQUACULTURE • WWW.WA S.ORG Redefining “Conservation Aquaculture” for Better Resource Management A critical step to discovering how aquaculture and conservation can better align is to define what that looks like. We found a need to redefine the meaning of Conservation Aquaculture for the 21st century. The term was originally coined in the late-1990s in reference to bringing endangered species back from the brink of extinction, starting with the Kootenai River white sturgeon — a species particularly close to my heart because my first foray into aquaculture started with white sturgeon when I was an undergraduate student. Given our research, we offer a more comprehensive and updated definition of the term: Conservation Aquaculture is the use of human cultivation of an aquatic organism for the planned management and protection of a natural resource . This perspective of aquaculture for conservation purposes —which needs to be an explicit intent from the beginning to fall under this classification — captures species-level interventions, like those for white sturgeon recovery, habitat restoration, targeted market mediation and production for improved water quality and ecosystem services. Critically, in creating this definition, we highlight the dearth of information around larger, ecosystem-scale consequences, good and bad, of aquaculture for conservation — such as feedbacks for improved biodiversity and reductions in greenhouse gas emissions. Aquaculture Conservation Limits and Potential on Land and Sea Although it may not be immediately obvious, aquaculture feed is a critical dimension for connecting aquaculture to global conservation objectives. In particular, terrestrial crops are playing an ever larger role in aquaculture growth, while inputs of wild fish used as a feed ingredient remain important but limited. About one- third of global landings from capture fisheries, or about 20 million t, are put towards things other than human food, chief among them animal feed. So, aquaculture is inherently tied to land and sea conservation because of this connection, among other reasons. Most wild fish species used in animal feeds are known as forage fish, mostly consisting of small pelagics like anchovies, sardines and herrings. This is not a new endeavor. We have global estimates going back to the 1960s of pigs and poultry using fishmeal as a feed ingredient; aquaculture is just the new, dominant user group. The concern is this: the supply of these forage fish is limited and other predators that people value in the oceans depend on them, including salmon and whales. While there is an abundance of literature assessing the dynamics and relative important of forage fish in marine ecosystem, there is limited research on if and how aquaculture can continue to grow sustainably in the coming decades. Using a global model and openly available data on wild fisheries, aquaculture and agriculture, we found that there are specific, achievable levers to prevent aquaculture from surpassing the ecological limits of forage fish by mid-century. This includes, forage fish no longer being fed to pigs and chickens, small reductions (to ~4 percent) in the diets of carps and other non- obligate carnivores, and China playing a bigger and more consistent role in using alternatives to fishmeal from forage fish in feeds (e.g., from trimmings). While some of these trends are already happening, more active adoption by farmers, feed companies and/or policy makers would expedite the transition to a more sustainable and stable future. However, there are aspects that could disrupt this sustainable potential, including things like stronger ecosystem-based fisheries management that reduces the allowable forage fish catch and greater human consumption of seafood in the future. And of course, there is climate change. While eating more seafood from aquaculture has aquatic resource limitations, a parallel modelling study we conducted shows that we could potentially spare millions of tons of crop-based feed and land in most areas around the world if human diets shift away from terrestrial meat and towards farmed seafood. The high efficiencies of aquatic species — because most are cold-blooded and do not have to expend energy to fight gravity —means that the feed and land-use consequences are relatively small compared to the impact of land-based animals, now and in the future. This aspect is particularly true for extractive filter feeders, like oysters, that do not need terrestrial feed crops. This means that aquaculture could potentially be part of the portfolio of land conservation strategies and does not necessarily have to compromise the aquatic environment under best practices — a future to ponder. Extractive aquaculture (Photo: NOAA). Pacific herring forage fish from a research tow, University of Washington (Photo: Halley Froehlich).