Arguably the single most important advancement in fisheries technology is the replacement of natural, easily degraded fiber ropes and twines with cheap, durable, and lightweight synthetic ropes and twines (Kristjonsson, 1959). Historically, hemp, cotton, jute, sisal, manila, silk, and linen were the primary natural fibers used to make fishing gear (Uchida, 1985; Brainard et al., 2000). They were treated with a wide variety of dyes, tars, and preservatives to retard their rate of degradation in the marine environment. Nevertheless, their failure, replacement, and repair rates were very high. These strength and durability limitations were major factors that limited catch sizes in many fisheries. Advances in polymer chemistry and production technology in the post–World War II period led to the manufacture of polyethylene, polypropylene, polyamide (nylon), and other synthetic fibers which have all but replaced the natural fibers used in fishing gear. Worldwide, these advances greatly contributed to the vast growth in fish and shellfish harvesting capacity and also set the stage for resource management challenges that are yet to be fully and effectively addressed by governments and industry. While achieving sustainable fisheries is still the primary challenge of management authorities, another result of this technological revolution that has largely been overlooked is the effect of the loss or discard of these persistent materials into the marine ecosystem. The same properties that make these new materials effective as fishing gear also make them particularly problematic as marine debris. Unlike their natural predecessors, the new materials can last for years or decades in the marine environment. They are largely impervious to biodegradation; they are resistant to chemicals, light, and abrasion; and because many of these synthetic fibers are buoyant, they can be transported long distances by ocean currents.
With the entry into force of the International Convention for the Prevention of Pollution from Ships, 1973, as modified by the Protocol of 1978 (MARPOL) Annex V and its implementation via domestic laws in the late 1980s, the at-sea discharge of plastics and other synthetic polymers, including fishing gear, was prohibited. This change from long-standing ship disposal practices, coupled with concurrent rising public awareness of synthetic materials–based marine debris (e.g., Manheim, 1986; Adler, 1987; O’Hara et al., 1988; Toufexis, 1988), increased focus on the problems associated with fishing gear lost or discarded into the marine environment. DFG is of particular concern because the use of synthetic materials has made fishing gear more durable and because it can continue to entrap, entangle, and retain marine organisms after it has been lost or discarded.
The committee defines fishing gear as any device or equipment or parts thereof, except vessels, used in the catching, attracting, gathering,