The Effects of Overfishing on Coral Reefs

Coral reefs have been called “The Rainforests of the World’s Oceans.” Bursting with life, they are home to large amounts of marine biodiversity, including many species of fish, sea turtles, sharks, and starfish. Reefs serve as a source of food and economy for millions around the world, help to protect coastlines from the damaging effects of storms and erosion, and provide habitat and serve as nurseries for many economically important fish species [1].

For most of humanity’s history, the ocean has been filled with seemingly endless bounty. In many cultures, seafood is a primary source of protein, and many of the important health benefits of eating fish are now well known, such as a rich source of Omega-3 fatty acids. 

However, as the human population on Earth has grown, so has our demand for seafood and other marine resources. As we have continued to make our fish catching technology ever more efficient, this has resulted in even greater pressures upon the world’s oceans to meet our demand for seafood [2].

High global seafood demand, unsustainable fishing practices, and a lack of sufficient habitat protections, regulations, and enforcement have now brought most fish stocks in the world’s ocean to levels that are near or beyond capacity for replacement. 

The impacts of overfishing on coral reefs

As with other ecosystem types, healthy coral reef ecosystems exist in a state of balance, and consist of a complex web of life. 

All lifeforms in these systems are ultimately dependent upon all of the other creatures in these ecosystems, with each one playing an important and unique role. If there are too few individuals of one species, but too many of another, this can potentially bring the entire ecosystem out of balance and lead to multiple negative physical and ecological effects.

An example of this imbalance has occurred when there has been overfishing of Groupers in the Great Barrier Reef ecosystem [3]. Groupers consume Damselfish, and without enough Groupers to help keep the Damselfish population under control, the Damselfish can become too numerous and create destruction in the reef by creating pockets in the reef to “farm” algae, which is their own food source. Without sufficient predation by the Groupers, too many Damselfish led to an overabundance of algae, which can eventually kill coral.

3 ways how fishing threatens coral reefs

• It leads to the removal of entire species or groups of species, impacting multiple levels within coral reef ecosystems.

• High occurrence of bycatch increases the mortality of non-target species [4].

• There can be negative physical impacts to the reefs from overfishing as well, such as damage to the reef itself by fishing gear, certain fishing methods, and when fishing boat anchors are used.

These negative impacts on coral reefs are made even worse by other stressors to coral ecosystems, such as coral diseases, pollution, and the threat of global climate change, where warming ocean temperatures and ocean acidification are leading to coral bleaching and death [4,5]. 

Efforts to curb overfishing on coral reefs

Despite dwindling fish stocks in coral reef ecosystems worldwide, efforts are currently underway to mitigate this trend and to embrace sustainable fishing.

Organizations like the World Wildlife Fund are taking actions to improve wild marine population levels through the establishment of sustainable fisheries, strengthening fishing regulations and compliance, improving fisheries management plans, the establishment of “no fishing zones,” and the promotion of sustainable aquaculture systems to relieve pressure from wild stocks [5].

Marine Protected Areas are now being created and managed to protect coral ecosystems that serve as refuges and allow species population levels to recover and reproduce [4,5]. These protected areas have been found to increase fish stocks in surrounding fishing areas and to provide a refuge for species such as endangered sea turtles and dugongs.

Organizations are helping to create alternative livelihoods to fishing in coastal communities, such as the development of ecotourism industries that economically support local communities and protect the local marine environment [5].

Decreases in bycatch incidents can be achieved through the provision of circle hooks that work more effectively to catch target species, and the use of exclusion devices in nets that allow larger animals such as sea turtles to escape. Efforts are ongoing in many coral reef communities to establish stronger policies and regulations on bycatch so that alternative, more ecologically-friendly fishing gear becomes the standard of practice [5].

Conservation organizations are also supporting and training local communities to manage their own marine resources and to collect data and monitor marine populations [5].

You can help too!

You can help efforts to conserve coral reef ecosystems by choosing to purchase seafood only from those sources that have been sustainably harvested.

References
[1] http://coralreef.noaa.gov/aboutcorals/values/
[2] https://www.worldwildlife.org/threats/overfishing
[3] http://sitemaker.umich.edu/gc2sec7labgroup3/over-fishing
[4] http://goo.gl/0LRdlM
[5] https://www.worldwildlife.org/places/coral-triangle