Hagfish, often called “slime eels” due to their unique defense mechanism, are ancient marine creatures largely unchanged for 300 million years. These jawless fish, found worldwide in deep oceans, possess a cartilaginous skeleton. Their most distinctive feature is the rapid production of a large volume of sticky, fibrous slime when threatened, expanding up to 10,000 times its original size in seconds. This ability, among other characteristics, has led to their use in various commercial applications, prompting examination of their ecological footprint.
Commercial Applications
Hagfish have various commercial applications, utilizing their skin, meat, and unique slime. Hagfish skin has established a niche market in the fashion industry. This “eel skin” leather, predominantly from Pacific hagfish, is used for accessories like wallets, belts, and handbags. Prized for its soft, thin texture and distinctive horizontal stripe-like patterns, the leather is often sewn in strips to create larger panels. Repurposing a byproduct from the food industry, this use can be more sustainable than other exotic leathers.
As a food source, hagfish consumption is concentrated primarily in Korea, where it is a delicacy known as kkomjangeo. In Korean cuisine, hagfish are commonly grilled with spicy sauces, onions, and garlic, or stir-fried. Diners describe its texture as firm and springy, with a mild flavor that adapts well to various seasonings. Most hagfish caught globally for food are exported to South Korea, including substantial imports from the United States.
Beyond traditional uses, hagfish slime’s extraordinary properties are a subject of ongoing scientific research for potential biomedical and industrial applications. The slime’s protein threads are remarkably strong and flexible, similar to spider silk and stronger than nylon. Researchers are exploring its use in novel textiles, including alternatives to petroleum-based fabrics for protective clothing and airbag components. The slime also holds promise for advanced hydrogels, used in products from medical adhesives and bandages to military applications like clogging boat propellers. Scientists are investigating methods to synthesize these proteins in laboratories, as hagfish do not reproduce effectively in captivity.
Ecological Considerations
Commercial hagfish harvesting raises several ecological concerns, particularly regarding population sustainability. Hagfish have slow growth rates and long lifespans, with Pacific hagfish living up to 40 years. They also exhibit low fecundity, with females typically laying only 20 to 30 eggs per batch, and their reproductive cycles are not fully understood. These traits make hagfish populations vulnerable to overfishing, as they cannot quickly replenish their numbers.
Hagfish fishing primarily involves baited traps, such as Korean tongbal or large bucket traps, deployed on muddy ocean bottoms. While this method has minimal bycatch of other finfish species, immature hagfish can be caught. Regulations often include minimum hole sizes in traps to allow smaller hagfish to escape. However, derelict hagfish traps contribute to marine plastic pollution and have been been observed entangling marine animals, including endangered Hawaiian Monk Seals.
The conservation status of hagfish species varies. The International Union for Conservation of Nature (IUCN) has assessed 9 of 76 known hagfish species as threatened, indicating an elevated extinction risk. Specific species like Myxine paucidens and Paramyxine taiwanae are listed as Endangered, and the Inshore hagfish (Eptatretus burgeri) is Near Threatened due to heavy fishing pressure. While the Pacific hagfish (Eptatretus stoutii) is “Data Deficient” by the IUCN, suggesting a need for more research, its population may be declining due to habitat degradation.
Despite these concerns, comprehensive conservation measures or specific legislation to protect many hagfish populations are often lacking. As scavengers cleaning the ocean floor and recycling nutrients, declines in hagfish populations could have wider ecosystem impacts.