Seaweed Farming: Avoiding the Potential Risk of Entanglement

As seaweed farming expands globally, researchers and leaders within the industry are investigating methods to ensure the safety of such upscaling, and to avoid any adverse effects that seaweed farming might present to the marine environment—especially to the endangered, threatened, and protected species that live there. Throughout the centuries-long history of seaweed farming, there have been no documented reports of marine mammal entanglement in the rope infrastructures that farmers use for growing seaweed.^{1, 2} Because absence of evidence does not necessarily equate to absence of risk, the seaweed industry’s proactive efforts will help reduce that risk as much as possible.

Any line dangling in the ocean can pose an entanglement threat to marine life—whether it’s a mooring line for a family’s boat or the buoy line of a fisher’s crab pot. In contrast, the lines used in seaweed aquaculture are fixed structures that are anchored securely to the ocean floor with heavy weights so that they remain taut under tension. Studies suggest that maintaining tight lines may help prevent entanglements, and this is already a standard best practice in seaweed farming.^{1, 2, 3, 4, 5}

Additionally, before receiving approval to begin operating at a specific site, a seaweed farm must conduct an environmental impact study and develop a comprehensive management plan to ensure minimal effect on the surrounding waters, flora, and fauna.^{1, 3, 4, 6, 7, 8, 9, 10} Of particular importance in minimizing interactions with wildlife is proper siting to avoid their migration routes, as well as their breeding and feeding grounds.^{1, 6, 7, 8} Due to climate change, some of these locations have been shifting over the years, so ongoing monitoring and reporting is crucial in mitigating potential encounters over the long term.⁸

These best practices, studies, and management plans help ensure that seaweed farming continues to develop and operate in a responsible manner as a sustainable industry, while serving as a steward of the ocean and contributing to vital global solutions.

The seaweed industry is exploring strategies to help ensure continued safe operations. For example, WWF is partnering with University of New Hampshire researchers to develop a low-cost sensor that can rapidly alert a seaweed farmer to an entanglement event, thereby decreasing injuries and increasing the likelihood of survival. Another WWF research partnership is exploring the use of composite rods that bend and break if a large marine mammal encounters them, preventing entanglement.¹¹

These endeavors, and other research projects, can help prevent possible future entanglement events. For instance, one study indicates that using red and orange lines increases their visibility for whales, so that encounters can easily be averted.^{11, 12} Other opportunities exist with infrastructure modifications, such as fewer vertical lines, shorter lines, stiffer lines, weak-link lines, breakaway lines, and recently developed bio-based lines, which can all potentially contribute to lower risks to marine wildlife, as well as to the marine environment in general.

Numerous studies show that seaweed farming has a low level of environmental risk, including entanglement.^{1, 2, 3, 4, 5, 6, 7, 9, 10} As seaweed farming increases around the world, WWF continues to support research efforts to fill knowledge gaps, ensure safety, and mitigate any potential environmental effects.