Derelict Gear Impacts
Derelict gear impacts extend beyond marine species to include habitat, human safety, the economic viability of Puget Sound’s fisheries, and the health of the Puget Sound ecosystem. Explore the links below to learn more about the impacts of derelict fishing gear.
Net Impacts
Crab Pot Impacts
Habitat Impacts
Ecosystem Impacts
Human Safety
Economic Impacts
Net Species Impacts
The vast majority of nets lost in Puget Sound are gillnets. Gillnets are made of a plastic monofilament and used to catch salmon. Gillnets can become snagged on rocky outcroppings and hung up on rocky ledges. The plastic material does not significantly degrade over time and marine life that becomes caught in the nets further attracts predators to the net and they become caught as well. The Northwest Straits Initiative has removed over 900 nets from Puget Sound waters, most of them gillnets. We use highly skilled commercial divers for this dangerous work and follow safety protocols that we designed in partnership with Washington State Department of Fish and Wildlife and Department of Natural Resources.
Our experience has shown that nets continue to catch marine life indiscriminately and can significantly smother and/or damage marine habitats. We record all animals that are found in derelict fishing gear and keep a database of these impacts. Click here to download a research report on mortality caused by derelict nets.
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Crab Pot Species Impacts
Commercial and sport crabbers are required to use a biodegradable cotton rot cord (also known as escape cord) on their pots so that if pots are lost, the cord will degrade and crabs can escape. Our research shows that only about a third of crab pots are properly equipped with escape cord and many derelict pots are found to continue fishing for months and even years. On average, a derelict crab pot will catch about 72 crabs a year. Primarily, crab pots become derelict when their buoy line is clipped by a passing vessel. Pots are frequently found in vessel traffic lanes and boaters out after dark have a challenging time seeing crab pot buoys.
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Habitat Effects
Both nets and pots harm marine habitat. When currents slow around crab pots on the bottom, the resulting turbulence can scour sediment and eelgrass, leaving holes and bare patches meters across. Nets are often found draped over rocky reef habitat and kelp, cutting off access to value habitat for marine species. We have found nets draped across centuries-old cloud sponge reefs, the reef scraped bare beneath. The good news is that for the most part habitat recovers quickly once derelict gear is removed. Research by the Northwest Straits foundation has found that a year after nets and pots are removed, habitat is about 90% recovered.
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Ecosystem Impacts
Derelict nets and pots kill indiscriminately, beyond just the target species they were intended to catch. Marine mammals, seabirds, fish, and invertebrates are all commonly found trapped in derelict gear. While it is difficult to estimate the overall ecosystem threat that derelict gear poses, we do know that in Puget Sound any unnecessary mortality of marine species is a problem. It has been said that Puget Sound is dying a death of 1,000 cuts; if that is the case derelict gear is a particular deep cut. Below are just a couple of examples of derelict gear ecosystem impacts.
• Derelict pots remove an estimated 74 Dungeness crab from Puget Sound each year. Dungeness crab larvae are a critical component of juvenile salmon diets.
• In 2008, the Northwest Straits Initiative removed a gill net with 162 seabirds, 14 salmon, 42 dogfish, 1,400 Dungeness crab and 1 harbor seal. Factoring in decomposition rates, it is estimated that this single net in 23 weeks time killed 1,800 birds, 450 salmon, 1,300 spiny dogfish, 16,900 crab, and 11 harbor seals. In an ecologically rich area like Port Susan bay, derelict gear can be a tremendous stress on the ecosystem and source of mortality.
• Derelict gear blocks access to habitat, making certain species more vulnerable to predation.
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Human Safety Impacts
Derelict nets and lines pose a threat to recreational divers, who have been caught and drowned in Puget Sound in the past. The Northwest Straits Initiative is working with divers and dive operators to raise awareness of the dangers of derelict gear.
Nets and lines can also foul ships’ props, causing a dangerous loss of steering or power. In 1993 the Korean Ferry the M/V Seo-Hae capsized when it turned sharply to the right after a 10 mm derelict line coiled around its prop shaft. 292 people drowned.
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Economic Impacts
The Northwest Straits Initiative recently completed a project to assess the costs and benefits of removing derelict fishing gear in Puget Sound. While it is difficult to estimate the total benefit of removing nets and pots from the marine environment, an approximation can be obtained by estimating the dollar figure of the commercially valuable species that would likely perish over the life time of the gear if it were not removed from the environment. Utilizing this method, project manager Natural Resources Consultants estimated the cost/benefit ration of removing derelict nets to be 1:1.27 and for removing derelict pots, 1:1.28. This analysis did not take into account the impact that derelict gear has on non-commercially valuable species or ecosystem structure and function. The analysis also does not attempt to capture the benefit that removing derelict gear might have on the costs of recovery of protected species, such as endangered salmon. Even in the absence of these analyses, the benefit of removing derelict gear from Puget Sound outweighs its costs. The results of the analysis are summarized in the tables below.
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