12.08.2025

Silent traps: the impact of fishing gears on marine wildlife

Author: Sara Allahverdiyeva

Did you know that fishing activities can lead to the “ghost fishing” phenomenon, disrupting marine ecosystems and contributing to the decline of many species? It is also one of the leading causes of plastic pollution in the ocean. Let’s take a closer look at Abandoned, Lost or otherwise Discarded Fishing Gear (ALDFG) and its hidden consequences on marine wildlife!

Ghost fishing is a phenomenon in which fishing gear that has been discarded at sea by human activities, either intentionally or accidentally, continues fishing, drifting in the water column and trapping marine animals and organisms. This concept began to gain more publicity during the 1970s and 1980s, after fishermen started to replace natural fishing nets made from cotton and hemp with non-biodegradable synthetic ones.

Ghost fishing is one of the dangers contributing to the death of marine life because marine organisms that become trapped in these materials are likely to either starve to death or become prey for other animals. Any fishing gear can become ALDFG (Abandoned, Lost, or Discarded Fishing Gear); however, the most common types are traps (used for catching small groups of organisms) and nets (used for catching large groups of organisms).

“CATCHING DURATION” OF ALDFG

The duration of fishing gear refers to the active period of time during which a ghost net continues to trap and kill marine life. Studies estimate that the catch duration can vary from 30 to 568 days, but the range depends on gear type, environmental conditions, and material durability. Let’s examine each factor:

Gear type

• Gillnets & Trammel Nets – typically made from synthetic monofilament nylon (PA), which is robust and resistant to water degradation, they can remain active for long periods of time, from months to years. The photo-degradation of nets can occur in surface waters; however, biofouling, the accumulation of microorganisms on submerged surfaces, can significantly reduce the breakdown process.

• Traps – generally made from more durable materials, like metals or plastic-coated steel, lost traps can catch marine organisms even for decades in low-oxygen water environments, where the corrosion rate is slow.

• Longlines – composed of a mainline (typically polypropylene (PP) or polyethylene (PE)), they have many branch lines (snoods) and hooks. Physical tension and hook drag make them more likely to degrade faster than nets or traps, mainly under UV exposure in saline water.

• Trawls & Dredges – very large, robust gear, made of heavy synthetic netting, often with multiple materials and metal frames or chains. Entire trawl nets rarely continue ghost fishing due to their bulk and the need for vessel movements, but they can still damage and trap marine species.

Photo by Canva

Material durability

• Nylon (PA), Polyethylene (PE), Polypropylene (PP) – all types of plastics are highly resistant to degradation. With low oxygen levels and UV exposure, it can take up to 450 years to photodegrade these materials, which contributes to actively trapping marine organisms.

• Metal (steel, aluminium) – used in traps, its corrosion rate depends on the temperature of the water and salinity; however, its degradation can take decades.

• Biodegradable alternatives – decomposing within months, biodegradable materials can potentially decrease both the ghost fishing phenomenon and the plastic pollution rate in the ocean.

Environmental conditions

• Temperature – warm water increases the degradation rate of fishing gear lost or abandoned at sea. In cold waters, decomposition can occur much more slowly.

• UV exposure – high UV exposure in surface water breaks down fishing gear faster, while in deep water and sediments, where sunlight is absent, degradation occurs more slowly.

• Oxygen availability – anaerobic environments, like sediments, deep waters, or hydrothermal vents, present a significant reduction in the process of degradation.

• Biofouling – the accumulation of marine organisms on the ALDFG surface, preventing the material from UV exposure, paradoxically extends fishing gear’s service life.

THE NEGATIVE EFFECTS OF ALDFG ON MARINE WILDLIFE

1. Marine organisms’ mortality
Gillnets, nets, traps, longlines, trawls, and dredges, remaining operational after being discharged, trap marine organisms such as fish, mammals, turtles, and crustaceans, ultimately leading them to death. Although there is a chance of survival for trapped species, it is significantly reduced due to the stress and starvation experienced by marine organisms during attempts to escape. Research shows that the fish survival rate was only 1–2%, while no more than 50% of the crustaceans survived. Shelled molluscs are less vulnerable to fishing gear, with significantly higher survival rates. A study conducted in Puget Sound in 2022 showed that one lost net can kill approximately 5 marine mammals, 556 invertebrates, 178 fish, and 4 seabirds over a period of 50 years.

2. Habitat destruction
ALDFG can cause significant damage to sensitive marine habitats such as coral reefs, seagrass meadows, and soft-bottom environments. Drifting fishing gear can destroy corals and disrupt the structure of the seabed, destroying the functionality of ecosystems. In some cases, ALDFG can function as artificial reefs, presenting conditions for colonization by marine organisms such as barnacles, sponges, and seaweeds. However, ghost nets do not provide the ecological benefits of a natural surface because, over time, as ALDFG degrades, microplastics and harmful chemicals enter the water and consequently the food chain. Furthermore, ALDFG can even block sunlight penetration in the water and disrupt oxygen flow, especially in shallow coastal areas, impacting photosynthetic organisms and leading to habitat degradation.

3. Pollution
Fishing gear makes up approximately 10–20% of all litter in the ocean and up to 70% of large floating plastics in some regions, since ALDFG commonly consists of nylon, polyethylene, and polypropylene, which persist in the ocean for decades or centuries and become part of marine debris. ALDFG is one of the most dangerous forms of debris because of its material durability, wide distribution, microplastic accumulation, and the threat it poses to marine life.
ALDFG, in fact, over time breaks down into smaller pieces, releasing microplastics into the marine environment. Microplastics are ingested by marine species and enter the food chain, leading to reproductive diseases, developmental disorders, immune toxicity, and genetic damage among marine organisms. In addition to microplastics, parts of the ALDFG can be swallowed by marine species, causing suffocation and immediate death.

Ghost net recovery operation by Worldrise

Photo by Worldrise

HOW TO ADDRESS THE ALDFG ISSUE?

To solve the various problems associated with ALDFG, several strategies can be implemented:

• Prevention actions: Implementing more durable designs for fishing gear can reduce accidental loss during fishing activities. Integrating GPS or RFID tracking technologies would enable fishers to monitor and retrieve their gear in case of drifting. Besides, providing educational training and awareness-building moments for fishermen is essential, ensuring that they follow best practices to handle their gear correctly in the event of sinking. Another important measure is the marking of fishing gear with identifiers, making it possible to trace gear back to its owner and discourage irresponsible disposal.

• Mitigation actions: The use of biodegradable materials, such as hemp, cotton, or plant-based elements in fishing gear, could significantly reduce marine organism mortality and harmful effects, preventing pollution. Another effective approach is to implement gear recovery programs that encourage fishers and divers to report ALDFG when found.

• Remediation: Organizing ghost net recovery activities with divers and fishermen, and involving them in ecosystem restoration where habitats have already been impacted by ALDFG, can be a way to become part of the solution.

BIBLIOGRAPHY

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Author: Sara Allahverdiyeva

Sara is a postgraduate student specializing in Environmental Engineering & Science. Growing up near the shores of the Caspian Sea, she developed an early understanding of the challenges marine life faces, particularly pollution and habitat degradation. These issues inspired her passion for marine conservation and her desire to raise awareness about safeguarding aquatic ecosystems. If she were a marine animal, she’d be a whale shark—calm and curious, yet keeping a peaceful distance and cherishing her own quiet space.