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Josh Goldman, founder and CEO of barramundi producer Australis Aquaculture, is on a mission to reproduceAsparagopsis, a tropical seaweed that could signicantly reduce the climate impact of beef production.

Early last year Goldman launched Greener Grazing to develop the technology to produce this pinkish-red sea plant at commercial scale. If it were added to the livestock feed of the world’s 1.5 billion cows, Goldman says it could dramatically reduce theirs and other ruminant animals’ burping of methane gas, which, according to the United Nations, is responsible for 14.5 percent of the world’s annual greenhouse gas emissions.

Goldman read original research from Australia’s James Cook University in 2017 on Asparagopsis’ potential to reduce methane burps. Intrigued, he called the researchers to find out where the seaweed was going to come from.

“They didn’t know – they were chemistry guys,” he said. “But it seemed like an important and interesting challenge to try and close the life cycle of Asparagopsis and accelerate its commercialization, as it could have a major real-world impact.”

Asparagopsis, a delicate, fragile and complex species of tri-phasic seaweed, has not been completely understood or successfully cultivated until recently. It has uniquely high concentrations of halogenated bromoforms, which target the specific microbes responsible for methane production in ruminant animals like cows, leaving more energy for digestion.

Farming and hatchery for the edible seaweed Gracilaria. Also known as limu, this seaweed is the most popular edible seaweed in Hawaii and most commonly used in poke.

Differences in ash behavior during hydrothermal treatment were identified based on multivariate data analysis of literature information on 29 different feedstock. In addition, the solubility of individual ele- ments was evaluated based on a smaller data set. As a result two different groups were distinguished based on char ash content and ash yield. Virgin terrestrial and aquatic biomass, such as different types of wood and algae, in addition to herbaceous and agricultural biomass, bark, brewer’s spent grain, com- post and faecal waste showed lower char ash content than municipal solid wastes, anaerobic digestion residues and municipal and industrial sludge. Lower char ash content also correlated with lower ash yield indicating differences in chemical composition and ash solubility. Further evaluation of available data showed that ash in industrial sludge mainly contained anthropogenic Al, Fe and P or Ca and Si with low solubility during hydrothermal treatment. Char from corn stover, miscanthus, switch grass, rice hulls, olive, artichoke and orange wastes and empty fruit bunch had generally higher contents of K, Mg, S and Si than industrial sludge although differences existed within the group. In the future information on ash behavior should be used for enhancing the fuel properties of char based on feedstock type and hydrother- mal treatment conditions. 

Chinese aquaculture has employed a balanced ecosystem approach for freshwater aquaculture for several thousand years. Utilizing species that feed at different levels of the food web has permitted China to have the largest freshwater aquaculture production in the world. This production has proved to be sustainable in the long run because there is balance in this system. This concept is just starting to be thought of for broader aquaculture, including marine operations at sea or on land, and fishery communities around the world.

The National Oceanic and Atmospheric Administration has developed a Sustainable Fisheries Implementation Plan that recognizes three key elements - fisheries, aquaculture and coastal communities - for obtaining sustained production of seafood in the United States. The concepts of carrying capacity for biological activities in  a hydrographic system; ecological balance between primary producers, primary and secondary consumers; and nutrient flows in ecosystems are essential elements for the future development of world aquaculture and fisheries.

This chapter documents the present status of selected polyculture systems being employed by the aquaculture industry, provides examples of balanced ecosystem approaches to aquaculture and fisheries, and examines the question of how to develop models for maximizing the production of seafood through fisheries and aquaculture working in harmony to minimize environmental impacts.