Destructive Fishing Methods – Turtle Island Restoration Network

Driftnets and Gillnets

Often described as invisible curtains of death or death nets, gillnets are walls of nets that float in the ocean, and gillnets that are not set at a particular location and drift with the current are called driftnets. The driftnet fishery is one of the worlds most destructive fisheries in terms of bycatch, or unwanted animals that are caught and discarded. Essentially, this gear entangles or kills almost everything that becomes entangled, in hopes that some of the thousands of animals caught or killed are swordfish, an expensive luxury product with dangerous levels of mercury. Only one in eight of the animals caught are swordfish.

This inherently destructive fishing gear has been banned by the United Nations, on the high seas, by a host of countries, and throughout the United States. Given the tremendous difficulty in enforcing environmental laws for such a destructive fishery, U.S. taxpayers bear the cost of managing this economically marginal fishery for almost no benefit. The end result is that the driftnet fishery is a net drag on the U.S. economy. (Read our report about the impacts of the California driftnet fishery.)

Longlines are long fishing lines that stretch up to 60 miles with thousands of hooks intended to catch swordfish and tuna. But for every single targeted swordfish, dozens more marine species are injured or killed as bycatch. Sea turtles become hooked while trying to take longline bait or become entangled while swimming through the walls of nearly invisible lines and hooks, drowning the turtles or leaving them fatally injured. Seabirds such as Laysan and black-footed albatrosses also dive for the bait and become hooked; worldwide, longline fishing has caused precipitous declines in most albatross populations. Pelagic longlines (longlines set near the surface) have been banned off the West Coast of the United States for more than four decades. Researchers estimate that 200,000 loggerhead and 50,000 leatherback sea turtles were caught worldwide by pelagic longline fishing gear in 2000 alone. The last time pelagic longlines were tested off California in 2011, more than 40 sharks were caught for every swordfish and over three quarters of the fish caught were unmarketable species. Off Hawaii, the shallow-set pelagic longline fishery was shut down in early 2019 for catching too many North Pacific loggerhead sea turtles the second consecutive year the fishery has exceeded the number of sea turtles it can legally injure or kill under the U.S. Endangered Species Act.

Aquaculture is the farming and cultivation of freshwater and marine animals and plants in controlled environments. Fish farming, or the cultivation of fish for commercial purposes in man-made tanks and other enclosures, is the primary form of aquaculture. The most common types of farmed fish are catfish, tilapia, salmon, carp, cod and trout. With the increase in overfishing and the demand on wild fisheries, the fish-farming industry has grown in order to meet the demand for fish products. Although fish farming can create jobs and reduce fishing pressure on certain wild stocks, fish farming can be harmful to the environment in many ways, including putting excess pressure on wild stocks that are used to create high protein feed pellets; amplifying and transferring disease and parasites to wild fish populations; polluting water systems with excess nutrients (fish feed & wastes), chemicals and antibiotics; compromising native gene pools if farmed fish and native species interbreed; and compromising the aesthetic beauty of coastline.

Traps and pots are used to catch crabs, lobsters, whelk, scup, black sea bass, and eels by dropping traps and pots to the bottom with bait. Because vertical lines run from the trap up to the surface buoy, traps and pots can entangle sea turtles, particularly leatherback turtles, around the flippers, neck, or carapace. If traps are heavily weighted, turtles can drown because they cannot reach the surface to breathe. Traps and pots also entangle marine mammals. Large whales, including endangered North Atlantic right whales, humpback whales, fin whales, and grey whales, are particularly susceptible to becoming entangled in trap or pot gear due to spatial overlap with fisheries and their feeding behavior. The effects of entanglement can range from no permanent injury to serious injury and death. If the traps are weighted down, entangled whales and dolphins can drown if they cannot reach the surface to breathe.

Trawling is dragging a net through the water behind a boat. The fishery targets whiting, red hake, dogfish, crab, shrimp, and flounder, but inevitably catches almost everything in their path. The risk of being captured in bottom trawls is so great for sea turtles many sea turtle species rest and forage on the bottom of the ocean that special devices known as turtle excluder devices (TEDs) were created to reduce these risks in some trawl fisheries and allow sea turtles and even small cetaceans to escape the net from an opening at the bottom. TEDs are only currently required in trawl fisheries targeting shrimp and summer flounder. In addition to sea turtles, marine mammals can become entangled by trawl gear when swimming to forage or migrate. Species that forage on or near the seafloor are at risk of being captured or entangled in netting or tow lines (also called lazy lines). Pilot whales and common dolphins in the Atlantic are particularly susceptible to being caught in bottom trawls. Capture in a bottom trawl could result in drowning from being trapped in the net and held underwater for the duration of the trawl; broken appendages or shell from the weight of the catch on top of them; injury from the drop to the deck when the net is emptied aboard the fishing vessel; stress and exhaustion from capture and release.

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Destructive Fishing Methods - Turtle Island Restoration Network