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Seaweed and Mussel Farming Increases Wild Fish Populations

New international research

Underwater view of fish swimming past columns covered in shellfish.
Aquaculture as Habitat A school of parore fish swim alongside mussels growing at a farm in New Zealand. © Lucy Underwood / University of Auckland

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Mussel and seaweed farming in New Zealand can increase wild fish populations and bolster diversity, according to new international research.

A research project by the University of Auckland and the University of New England assessed the diversity and abundance of wild fish and invertebrates on farms growing kelp and/or mussels compared to non-farmed sites in the Hauraki Gulf and the Gulf of Maine, United States.

The research, which was supported by The Nature Conservancy in New Zealand and Maine, found mussel and seaweed farming has potential to provide habitat for marine species, as well as providing food for people. Dr Andrew Jeffs, professor of marine science at the University of Auckland, says the fish populations found on mussel and kelp-mussel farms in the Hauraki Gulf were equal to or greater than those at the non-farm sites, in both diversity and abundance.

“In an examination of gut contents of snapper living inside and outside New Zealand green-lipped mussel farms, fish living on the farm sites were also found to be eating more nutritious diets than those living in natural habitat.”

Quote: Dr. Rob Major

This research underlines the role that aquaculture can play in restoring our natural environments, as well as local communities by contributing to employment and economic development.

Marine Ecosystem Advisor, The Nature Conservancy Aotearoa New Zealand

Dr. Jeffs says these results are a promising sign that mussel and kelp farms can provide both settlement and nursery habitat and an important source of food for wild fish species.

“When implemented in the right places, aquaculture could bolster biodiversity and contribute to the productivity of fisheries.”

“This project is really the first of its kind,” says Dr. Rob Major, marine ecosystem advisor from The Nature Conservancy Aotearoa New Zealand.

“Before this, only a handful of studies had quantified commercial aquaculture’s value as habitat. By measuring habitat benefits in Maine and Aotearoa, we’re starting to fill a critical gap in knowledge about the effects of seaweed and shellfish aquaculture on biodiversity in coldwater ecosystems.”

Underwater view of mussels and kelp growing in a column.
Mussels and Seaweed An aquaculture farm in New Zealand. © Aquaculture New Zealand/Andrew Simpson

“The aquaculture industry in Aotearoa has growth aspirations. This research underlines the role that aquaculture can play in restoring our natural environments, as well as local communities by contributing to employment and economic development.”

The Maine study highlights the importance of timing in the overlap between kelp farms and species presence in the nearshore. During the Maine kelp growing season (October to May), there was no significant difference in species abundance or diversity between farm and non-farm sites. “This is good news in a region where seaweed farming is highly seasonal, with farmers removing the kelp and equipment after the spring harvest,” says Dr. Carrie Byron, associate professor at the University of New England.

“What we see here in Maine is that farm ecosystems are not a replacement for wild ecosystems, but they do offer some restorative or regenerative properties that can help buffer against climate impacts, at an ecosystem level and a human level.”

While this and other research shows that kelp and shellfish farms can provide important ecosystem benefits, the future of the industry depends on social acceptability, also known as the social license to operate, and the perceived value consumers may place on ecosystem services provided by aquaculture. To better understand the potential importance of aquaculture’s ecosystem services in the marketplace, researchers from the University of New England, the University of Massachusetts and Stanford University asked U.S. consumers what price they would be willing to pay for a range of seaweed products. After being shown a short video about the ecosystem services associated with seaweed farming, consumers indicated that they were willing to pay more for the same products.

“It’s clear that consumers care about the environmental impact of seaweed products,” said Dr. Heidi Alleway, senior aquaculture scientist from The Nature Conservancy Worldwide Office. “This justifies continued exploration in this line of inquiry, which can ultimately help fully realize aquaculture’s full environmental potential.”

Learn More

Learn more about this project and read the studies: https://www.aquaculturescience.org/habitat-value-of-kelp-aquaculture/

Media Note

The New Zealand research was conducted at Gold Ridge Marine Farms Ltd. 

High-res images are available on request.

The Nature Conservancy is a global conservation organization dedicated to conserving the lands and waters on which all life depends. Guided by science, we create innovative, on-the-ground solutions to our world’s toughest challenges so that nature and people can thrive together. We are tackling climate change, conserving lands, waters and oceans at an unprecedented scale, providing food and water sustainably and helping make cities more sustainable. The Nature Conservancy is working to make a lasting difference around the world in 81 countries and territories (40 by direct conservation impact and 41 through partners) through a collaborative approach that engages local communities, governments, the private sector, and other partners. To learn more, visit nature.org or follow @nature_press on X.