Marine debris and plastic pollution on the Great Barrier Reef are of significant concern to both commercial and recreational fishermen. In particular the impacts on marine life affect fishermen in diverse ways. Fish stocks are affected by large ghost nets and on a smaller but more diverse scale by discarded fishing line, lures, netting and other fishing items such as polystyrene floats. A major concern is microplastics and plastic fibres which adsorb toxins such as herbicides and pesticides in the water. These small plastics are eaten by fish or accumulated by filter feeders such as oysters and mussels and even enter the food chain when consumed with phytoplankton and zooplankton.
Fishing waste and lost or discarded tackle also have a large impact on the ocean, wildlife and the Great Barrier Reef. The Great Barrier Reef Marine Park Authority lists plastic marine debris as one of the threats to the reef and suggests action by community, industry and government to choose sustainable options, minimise waste and undertake stewardship activities. Plastic is life-threatening for marine species. Impacts include entanglement, ingestion, toxic exposure, disease and death. Marine debris negatively affects all species of sea turtle and more than half of all known species of marine mammal and seabirds. In a single incident recorded off the Gulf of Mexico in 2018, a mass death of more than 300 Olive Ridley sea turtles was caused by entanglement in ghost nets. Plastic waste increases the risk of coral disease outbreaks and consequent damage to reefs, as well as the loss of fisheries and coastal protection. Microplastics are consumed by coral posing further risks to coral health. Community and tourism benefits, such as enjoyment, visual features, appreciation, tourism satisfaction and aesthetics of the Reef are also affected. Marine debris can also pose a navigation hazard with nets and ropes entangling propellers and large items causing hull breaches.
Key types of discarded fishing gear (or ‘ghost gear’) are nets, traps, pots, lines and artificial drifting fish aggregating devices. One lesser-known gear type in proliferation along the Great Barrier Reef coastline, however, is Cyalume glowsticks. Glowsticks are used largely in pelagic and longline fisheries as fish attractants and to improve fishers’ view of their lines at night. Over the last decade however, Cyalume glowsticks have proven a primary source of plastic pollutants with over 18,681 Cyalume glowsticks collected by the Australian Marine Debris Initiative network from along Queensland’s coastline. Glowsticks can disrupt fish foraging and behaviour through light pollution, and the chemical solutions contained within light sticks can be toxic to humans as well as marine creatures, with one study showing a 100% reduction of Artemia brine shrimp hatchability after just 48 hours exposure to light stick contents.
The International Convention for the Prevention of Pollution from Ships as identified by the protocol MARPOL Annex V, “prohibits the discharge of all types of garbage into the sea.” This includes sewage, food scraps, oil and grease, animal carcasses, and cargo residues as well as plastic waste including packaging, bottles, plastic parts of e-waste, synthetic ropes, fishing nets (‘ghost nets’), floats, monofilament lines, and strapping or wrapping associated with ships’ stores. However, a CSIRO review of 68 studies from 32 countries and territories found that the most common causes of fishing gear loss in the ocean are bad weather, gear getting tangled on the seafloor, or with other fishing equipment in an issue known as ‘gear conflict’.
The CSIRO study estimates that 6% of nets, 9% of traps and 29% of lines lost in the ocean each year were found to come from commercial fisheries. It is also clear that Illegal, Unreported, and Unregulated (IUU) fishing is a further key driver of gear loss, where the presence of illegally operating vessels and increase of fishing pressures result in an increase of fishing effort. The instances of lost or discarded fishing gear have shown to be proportional to this increased fishing effort.
In addition, plastic ghost gear can enter oceans and rivers from aquaculture farming. The leading cause of gear loss from fish farms is extreme weather such as large storms, as well as poor waste management, installation wear or failure and vandalism.
Fishers can reduce tackle and fishing related litter on the reef in a number of ways, including:
- Reducing overall plastic use
- Switching gear types for non-synthetic alternatives where possible
- Using reusable fishing gear
- Implement a plastic waste monitoring program
- Responsible disposal of used fishing gear, including recycling
- Strategizing ways to reduce gear entanglement on the sea floor and gear conflict
- Tagging fishing gear with boat or farm registration and year
- Report instances of lost gear
- Retrieving lost and discarded litter, tackle and nets from the ocean
- Reporting cases of illegal or unregulated fishing
- Tackle bins and signage for recreational fishers
- Education amongst fishing vessel crews and recreational fishers
- Support research and development of new biodegradable gear types and waste management systems
The Reef Guardian Program is a hands-on, community-based approach that includes schools, local government, fishers, farmers, and graziers who have pledged to make a real difference to the health and resilience of the Reef. The Reef Guardian Fishers program recognises commercial fishers who are fishing sustainably and maintaining the health of the Great Barrier Reef while building the future of their fishery, their business, and the Reef.