The rapid rise of industrial aquaculture has been accompanied by the expanded use of plastic infrastructure. Little to no attention has been given to the environmental consequences of accidentally lost plastic gear. No mention of lost aquaculture plastic is made in the 2014 FAO Annual Report or its “Code of Conduct for Responsible Fisheries”. Lost aquaculture plastic is not monitored, and no regulatory remedies have been created, nor is it called out by certification organizations.
Derelict plastic gear used in aquaculture is being found in studies of bays, beaches and the open ocean, where it entangles a multitude of species. Photo-degraded plastic bits enter the food web by mimicking natural prey. In addition to being non-nutritive and non-digestible, plastics transport toxic chemicals used in their manufacture and absorbed from seawater. This causes stomach blocking and laceration, starvation, liver deterioration, endocrine disruption, stressed protein profiles and cancer.
Currently, aquaculture provides almost half of all fish we consume. This is projected to rise to 62% by 2030 with a total tonnage estimated to be around 138 million metric tons.
The equipment used for both aquaculture and capture fishing up until the 1960s consisted of metal, wood, and natural fibers, which would readily undergo oxidative decay and/or biodegrade in aquatic environments. This is no longer the case. Today growing and catching seafood demands nets, tubes, ropes and floats made of polyethylene (PE & PET), nylon, polypropylene (PP) and poly vinyl chloride (PVC), plastics that biodegrade exceptionally slowly, breaking into tiny fragments in a centuries-long process.
Expanded polystyrene, (“Styrofoam”) floats keep mussel and oyster growing structures afloat, but readily lose their small, loosely fused, foam balls to the surrounding water. Near oyster grow-out facilities in Hiroshima Bay, Japan, 99% of shoreline debris was Styrofoam. “The huge quantity polystyrene on South Korean Beaches is generated by aquaculture activities in coastal waters.”
Microplastics are increasingly being found in shellfish meat. Annual dietary exposure for European shellfish consumers can amount to 11,000 microplastics per year, and poses a threat to food safety. “Bivalves are of special interest since their extensive filter-feeding activity exposes them directly to micro-plastics present in the water column.” (Cauwenberghe & Janssen).
Support for aquaculture by governments, rightly concerned with depletion of the marine food web by wild capture, needs to be supplemented by funding for marking, monitoring, and researching, and marking plastic aquaculture gear. Preventing lost gear must become part of Best Management Practices (BMPs) promulgated by industry and certification organizations. Sustainably farmed fish and plants must use materials that are safe for people, the environment, and wildlife, and eliminate its loss to the environment.
(This article originally appeared on Algalita. It has been reprinted here with permission.)