What happens when a fishing nuisance turns out to have commercial value? Researchers in Spain say jellyfish accidentally caught by small-scale fishers could be used as a source of high-quality collagen instead of being discarded as waste.

The work comes from a new Frontiers in Marine Science article co-authored by researchers Ballesteros and Raquel Torres, a PhD student at the same institute. Their study looked at jellyfish bycatch in Spain, worked with fishers to understand how they see it, identified the species most often caught, and tested if Rhizostoma pulmo could be a sustainable source of collagen.

Ballesteros said the research grows out of a long-standing interest in marine ecosystems and applied science.

“We have always been fascinated by nature and by the many unanswered questions surrounding marine ecosystems,” Ballesteros said.

“The sea is dynamic, complex, and full of interactions that are still not fully understood. For us, becoming researchers was a natural way to combine curiosity with the possibility of contributing useful knowledge to society.”

Ballesteros said jellyfish are often seen only in negative terms, despite their ecological role and scientific potential.

“Jellyfish are fascinating animals. They have inhabited the oceans for millions of years, play important ecological roles, and possess unique biological characteristics that we are still discovering,” Ballesteros said.

“However, they often carry a negative reputation, usually associated only with stings or blooms. Part of our work is to help people understand them better, showing their true role in marine ecosystems as well as their scientific and biotechnological potential.”

The researchers said their current work focuses on marine biological resources that are often overlooked, underused or seen as problematic, in line with circular bioeconomy and zero-waste strategies.

Torres said the project shows how jellyfish bycatch, often treated as a burden by fishers, could be turned into a resource.

“Jellyfish bycatch is often seen as a nuisance for fishers because it damages nets, increases workload, and can reduce the value of commercial catches,” Torres said.

“However, jellyfish are also rich in collagen, a biomaterial widely used in cosmetics, medicine, food technology, and tissue engineering.”

“By demonstrating that jellyfish bycatch can provide collagen without compromising quality, we propose a circular bioeconomy solution: reducing waste, creating new economic opportunities, and supporting small-scale fisheries at the same time.”

The team said working directly with fishers was one of the most valuable parts of the study.

Torres said fishers contributed practical knowledge about seasonal changes, fishing gear and species behaviour, and many gave near-daily reports on catches and non-catches. They also shared photographs and observations from the sea.

“This was particularly important, as data on non-catches are extremely valuable for understanding patterns of presence and distribution,” Torres said.

She said many fishers were open to the idea of recycling jellyfish bycatch if it could bring in extra income and cut waste, but they also pointed to problems.

“They highlighted the lack of infrastructure, limited market demand, the absence of clear incentives, and the need for specific training,” Torres said.

“In other words, they were willing to participate, but they need systems that make participation truly viable.”

In the lab, the researchers extracted collagen from R. pulmo jellyfish collected in two ways: animals accidentally caught in fishing nets, and animals collected by hand-net to better preserve their structure. They then compared the collagen using analytical techniques to assess protein profile, apparent molecular weight distribution, structural integrity, and molecular and crystalline features.

Torres said the result was clear.

“The key result was very encouraging: collagen obtained from bycatch jellyfish showed the same main structural features and very similar quality to collagen from carefully collected specimens,” Torres said.

“In other words, despite being considered a discarded material, the accidental capture did not significantly damage the collagen.”

She said that finding supports the use of jellyfish bycatch biomass as a sustainable raw material with biotechnological value.

The researchers said jellyfish collagen could be used in cosmetics, biomedical products such as wound dressings and tissue regeneration scaffolds, drug delivery systems, and potentially nutraceutical or food-related products.

Torres said regenerative medicine is one of the areas that interests the team most.

“Marine collagen is attracting attention as an alternative to mammalian collagen because it may reduce concerns linked to zoonotic diseases, religious restrictions, or consumer preferences,” Torres said.

Ballesteros said one persistent misconception is that jellyfish have no positive value and that discarded materials are automatically low quality.

“Our results show that, with proper handling and scientific validation, bycatch biomass can become a valuable resource,” Ballesteros said.

She also said the team wants to see more long-term studies on jellyfish bycatch in different fisheries and regions, and more work on improving collagen extraction, scaling up production and testing commercial uses in industrial settings.

Ballesteros said open science has helped the work reach beyond academia.

“By publishing openly, our findings can be accessed not only by scientists, but also by fishers, environmental organizations, policymakers, students, and entrepreneurs,” Ballesteros said.

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