Barbed-wire jellyfish, also known as String of Pearls Jellies or string jellyfish, struck two Scottish fish farms in late 2024, killing nearly 200,000 salmon.
Around the same time, the Norwegian government warned the nation’s aquaculture sector about potential barbed-wire jellyfish attacks after receiving reports of their presence in coastal waters. The country’s Food Safety Authority then urged farmers to take proactive measures, including euthanization, to prevent losses.
The sudden increase in jellyfish attacks in European waters, including fish farm invasions, stems from a mix of environmental and human-driven factors. Key contributors include climate change and ocean warming (amplified by El Niño, shifting currents, and weather patterns), overfishing and predator loss, as well as coastal pollution and nutrient overload.
Moreover, coastal developments and fish farms create artificial structures that inadvertently disrupt ecosystems and serve as nurseries for jellyfish polyps, further fueling their reproduction. This is particularly true for open-net fish farms, which pollute surrounding waters with medication, uneaten feed, and waste. Given these concerns, EFTTA strongly advocates for a transition from open-net fish farming to closed containment systems.
As these factors continue to intensify, the threat to fisheries and aquaculture is expected to persist, necessitating stronger mitigation efforts such as jellyfish-exclusion technologies and ecosystem-based management strategies. This requires a multi-layered approach combining technology, environmental management, and regulatory measures including:
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Physical barriers, such as electrified fences, fine-mesh nets, and pump-driven removal systems, though these can be costly, maintenance-intensive, or species-dependent.
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Environmental monitoring using satellites, drones, and AI-powered underwater sensors improves early detection, though high investment and data complexity remain challenges.
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Ecological strategies, like protecting natural predators and controlling plankton blooms, offer long-term solutions but require ecosystem-wide coordination.
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Operational and policy measures, including farm relocation, closed containment farming, industry regulations, and emergency response plans & euthanization protocols, help reduce losses but often come with logistical, financial, and ethical concerns.
With climate change intensifying, jellyfish-related threats are expected to increase. Future research should focus on more efficient exclusion technologies, AI-driven detection systems, and ecosystem-based solutions. Policymakers must also enforce stronger environmental protections to reduce factors like nutrition excess and overfishing that contribute to jellyfish blooms.
Source: SeafoodSource January 23, 2025
© pictures:
Seascapeza - Own work, CC BY-SA 3.0, commons.wikimedia.org/w/index.php
Massimiliano De Martino.The original uploader was Yoruno at Italian Wikipedia. - MondoMarino.net, CC