By: Julia Saper
When faced with the insurmountable threats to the world’s oceans, specifically coral reefs, it is easy to adopt a defeatist attitude. However, I am writing this to urge readers to implement doable changes in daily routines that can contribute to abating these very issues. Choose your thing and stick to it. Today I want to address overfishing and other destructive fishing practices. Approximately 90% of global fisheries have been fished to their limit, over their limit, or have collapsed. If the current trend persists, we could witness a worldwide failure of fisheries in the decades to come. Seafood is a critically important part of our diet, a key contributor to coastal economies, and is vital to the health of coral reefs.
Overfishing is defined by catching more fish than the ecosystem can support. In these situations, fish are being caught at a faster rate than they can reproduce. In coral reefs, for example, removal of too many herbivorous fish, such as surgeonfish and parrotfish, may instigate the transition of a coral dominated reef to an algal dominated reef. Studies have shown that exclusion of herbivorous fish cause a significant increase in macroalgae which affects reproductive rates, recruitment and survival of corals (Hughes 2007). Excessive algal growth thus reduces the resiliency of the coral reefs which means longer recovery from bleaching events. Overfishing is not only harmful to reefs when herbivores are removed en masse, but also removing large pelagic reef fish and sharks may have significant top-down effects on the ecosystem. In Australia’s Great Barrier reef, overexploitation of significant ocean predators has been linked to the outbreak of the coral predator, the crown of thorns starfish, Acanthaster planci (Jackson 2001). Larger reef fish, such as grouper, have long life spans and are therefore slow to reproduce. These fish are the most vulnerable to overfishing.
Destructive fishing practices, such as dredging, gill nets, bottom trawls, blast, and cyanide fishing can significantly alter reef environments. Blast fishing practices, often with the use of dynamite, completely obliterates the corals. Consequences of trawling and dredging practices include stirring up sediment, bycatch, disrupting bottom dwelling species and sensitive seafloor habitat. Many of these practices do not necessarily result in catching the targeted species and have high levels of unintended bycatch. The environmental cost of these methods far outweighs their benefit.
Being informed consumers is the best defense against overfishing. The Monterey Bay Aquarium’s Seafood Watch and Georgia Aquarium’s Seafood Savvy program are great resources. The Monterey Bay Aquarium divides seafood choices into “best choices”, “good alternative”, and “avoid.” The “best choice” fish may be from well-managed fisheries, caught, or harvested in low impact ways and are harvested well below the maximum sustainable yield. The “good alternatives” may have some negative environmental issues, but are generally suitable eco-friendly choices. Animals listed as “avoid” may be unsustainable, overfished, or caught using destructive fishing practices. Similarly, Georgia Aquarium divides seafood into the categories of “Best”, “Good”, and “Avoid.” These are great resource to utilize when eating out as they are easily accessible, well organized, and reliable.
In terms of certifications to look for when shopping for seafood, one certification that a well-managed, sustainable fishery can achieve is the blue Marine Stewardship Council (MSC) eco-label. This voluntary eco-label assures traceability from your plate to an MSC certified fishery. For more information on the criteria for this certification and what it means to be a sustainable fishery, make sure to update your subscription preferences and start receiving our Education emails!
Words to know:
Herbivorous fish – algae eating fish
Recruitment – process of drifting planulae (coral larvae) attaching to a substrate
Top down effects – an ecological process observed when predators have significant impacts on the populations of organisms lower in the food chain
Resilience – the capacity of an ecosystem to respond and recover from a disturbance
Bottom – Trawling – Use of fishing nets dragged along the ocean floor typically used to catch shrimp or benthic species such as halibut, sole and flounder
Dredging – Large metal baskets dragged along the ocean floor as in trawling
- Hughes, Terence P., Maria J. Rodrigues, David R. Bellwood, Daniela Ceccarelli, Ove Hoegh-Guldberg, Laurence Mccook, Natalie Moltschaniwskyj, Morgan S. Pratchett, Robert S. Steneck, and Bette Willis. “Phase Shifts, Herbivory, and the Resilience of Coral Reefs to Climate Change.” Current Biology4 (2007): 360-65. Web.
- Jackson, J. B. C. “Historical Overfishing and the Recent Collapse of Coastal Ecosystems.” Science5530 (2001): 629-37. Web.