Sharks And Other Predators Are Essential For Ocean Health
This week, the Discovery Channel aired its world famous Shark Week; several days of programming that celebrates the might and mystery of one of the planet’s most feared and misunderstood predators. Much of the programming during this annual event focuses on the shark’s intense killing power, and the often disastrous results that can occur when humans and sharks interact.
As humans, we’re not used to being challenged for our spot at the top of the food chain. The idea that a wild animal could possibly view us as prey is unnerving, and the reason that shark nets and shark alarms are used to religiously in coastal areas. Enhanced media reports of shark attacks and movies like Jaws have taught us that sharks are the enemy, and need to be eradicated or we’ll never be safe.
What many fail to realize is that an ocean without sharks is a truly terrifying prospect, one that inches closer and closer to reality every moment we refuse to protect these ancient predators.
According to a 2008 report by Oceana, “as top predators, sharks help to manage healthy ocean ecosystems. And as the number of large sharks declines, the oceans will suffer unpredictable and devastating consequences. Sharks help maintain the health of ocean ecosystems, including seagrass beds and coral reefs.”
The report goes on to point out that apex predators like the shark help to maintain a healthy ecosystem by conducting population control on the wide variety of species in their diet, as well as influencing where those populations choose to congregate.
“Apex predators not only affect population dynamics by consuming prey, but they also can control the spatial distribution of potential prey through intimidation. Fear of shark predation causes some species to alter their habitat use and activity level, leading to shifts in abundance in lower trophic levels. Top predators affect other animals in a cascade effect throughout the ecosystem, ultimately influencing community structure.”
Commercial shark fishing, climate change, and shark finning are all human practices that have sparked a rapid decline in global shark populations. Oceana estimates that shark finning kills 26 to 73 million sharks each year just for the fins alone. This means that humans, not sharks, are the ocean predators that ought to strike fear into the public’s heart.
Surveys show that the abundance of the 11 great sharks (sharks more than two meters in length) along the eastern coast of the United States has declined to levels of functional elimination. Without these sharks, 12 species of rays, skates and smaller sharks — have increased in abundance by as much as ten-fold. The species that increased most in abundance was the cownose ray, which migrates up and down the eastern coast consuming bivalves like scallops, clams and oysters.
These bivalves are essential for filtration of ocean waters. Without them toxic blooms of algae could choke out all forms of life in coastal areas, threatening both the environment and the humans that depend on them.
Want to help? Add your signature to the below petition to protect sharks once and for all!
Image Credit: Flickr - usfwspacific