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Habitat Destruction

marine debris

(above photo: Discarded fishing nets, ropes and plastic bottles, Tonsina Bay, Alaska. © Carl Safina)

A number of human activities can negatively affect the health of ocean habitats and ecosystems, including fishing, the spread of invasive species, and pollution. This in turn can negatively affect ocean animals. If we want to have healthy fish populations, they need healthy places to live, grow, and reproduce.

Habitat Destruction from Fishing
Fishing gears that touch the sea bottom can cause damage to ocean habitats. Gears that are dragged along the bottom, including bottom trawls and dredges, cause the greatest damage. These fishing methods stir up the bottom sediment, leave large scars on the ocean floor, and crush or displace anything in their path, including structural organisms like corals, sponges, or seagrass and bottom-living species like crabs and snails. They can turn physically diverse environments teeming with life into barren desserts. In heavily fished areas, or in areas with coral reefs, it is essentially equivalent to clear-cutting the rainforest!

The Safina Center works with other scientists and conservationist to promote the protection of vulnerable and important ocean habitats from destructive bottom fishing gears. Closing off areas to bottom fishing methods can help ocean habitats to recover and remain in-tact. Low-cost gear modifications or switching to less destructive fishing methods can also help protect ocean habitats.

Invasive Species
Invasive species are animals and plants that have been accidentally or intentionally introduced by humans into places where they are not normally found. In the ocean, species are often transported to new places through ships’ ballast water—the water that cargo or large passenger ships suck into their tanks to stabilize the boat. More recently, some species have also ended up in new places by clinging onto plastic and other marine debris that pollutes the ocean.

While many species don’t survive in their new habitats, the ones that do can sometimes explode in numbers because they are now freed from their predators and diseases. In their new homes, invasive species can create big problems for native species and ecosystems. They may prey on native species or they may compete with them for food and shelter. One strategy to help control invasive species that is becoming increasingly popular is to eat them!

Marine Debris
Scientists estimate that 8 million items of litter enter the ocean every day, and that about 6.4 million tonnes of marine litter are disposed of in the oceans each year. This litter includes plastic bottles, plastic bags, food wrappers and containers, disposable lighters, abandoned fishing gear, and much more. Ocean currents carry this trash throughout the ocean and much of it accumulates in the center of ocean gyres, creating large garbage patches. This debris makes for an unpleasant ocean environment and kills marine life. Much of the debris is plastics, which break down very slowly into tiny particles. Ocean animals consume these plastic particles and we consume them too when we eat fish or shellfish!

The Safina Center is working hard to help bring more awareness to this massive issue. Follow our posts on plastic pollution in National Geographic Ocean Views.

What You Can Do
By choosing fish from fisheries that don’t destroy bottom ocean habitats and by eating invasive species (try lionfish or Chesapeake Bay blue catfish!), consumers can be part of the solution. The Safina Center’s seafood assessments consider how fishing affects ocean habitats and the broader ecosystem as one of its four core criteria. Check out our Healthy Oceans Seafood Guide. Additionally, you can help keep fish habitats healthy by reducing your plastic use and participating in beach/ocean cleanup efforts!


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