Who's the Bigger Predator?

Its that time of year again… The familiar low baseline of a certain film soundtrack is heard everywhere. Spectacular slow motion imagery is shown. There are endless discussions about the musculature and teeth that make these legendary ocean creatures into "monsters of the deep". Ladies and Gentlemen, we hope you are having an excellent Shark Week!

We here at Sailors for the Sea love Shark Week. For the past 26 years, Shark Week has been one of the major events that gets people interested in ocean sciences. The more people learn about the oceans, the more they will want to protect them.

Part of the appeal of the week is that it can portray sharks as vicious attackers, stalking down their pray in ways often violent and powerful. This is because many shark species are apex predators, sitting at the top of their respective food chains. In the ocean, sharks tend to have the biggest and scariest reputations of all the  predators.

Despite this, humans still come in as the top predator in the ocean. Shark fin soup, considered a delicacy by many, finds sharks being used exclusively for their fins. Fisheries that target other speices will often catch, accidently kill, and dispose of sharks as bycatch (non-intended catch). In addition, sharks are fished for a variety of their properties. From using their skin for leather, to the liver oil for supplements and cosmetics, human beings are predators of sharks. But because perception of sharks is largely that of a vicious killer, it can make us less inclined to fight for their protection.

That being said, why should we fight for the shark? The reasons are many, but here is one that is fairly simple. Sharks, being apex predators, control the population sizes of smaller carnivores (meat eaters). If the population sizes of sharks were to be drastically reduced, the populations of the animals that they eat would grow. As the small carnivore population grows, the herbivore populations would be seriously decimated, leaving the marine plants with very few natural predators. This is the kind of upheaval that would cause some far reaching reverberations in the delicately balanced ecosystem. 

Let's use that fantastic image above as a clear-cut example. Great Whites usually hunt down seals in the beginning of winter to take advantage of their fatty meat. They usually target younger seals, who would reproduce at the beginning of spring. If the seal population were to reproduce at replacement rate every year, a shark eating one seal would reduce the population by two (the seal that was eaten and it's now nonexistent offspring). Now before grabbing tridents in defense of the cute little rascals, lets take a look at what they consume. One thing that harbor seals eat is salmon. One could say, "Good taste! They're excellent poached." While this is true, salmon do not exist in unlimited amounts in the oceans, and the unnatural rise of a predator (in this case, the rise of the seal brought on by the decline of the shark) can cause an untimely decline of its prey.

Nurse Shark, Friendly, shark, florida

Though this is a drastic and oversimplified example, the balance of ocean ecosystems is in quite sensitive. It is essential for the ocean food webs that sharks maintain healthy population sizes. Sharks live longer lives, reproduce later in life, and produce relatively little offspring compared to other fish species. This means that if the shark population were to decline, it could take a very long time to return to previous strength. Our biggest concern over sharks should be with their unnatural predator: humans.

Below are some resources where you can take action, sign a petition or just learn a little more about these fantastic creatures:

Shark Research Institute is a nonprofit dedicated to promoting conservation of sharks through research. In addition to donating to their cause, you can join one of their expeditions and experience sharks in the wild, or download education materials that can be incorporated into home or classroom.

The Pew Environment Group is running a week long special edition that discusses seven victories in shark conservation over the past year. They also have a pledge that you can sign to support the populations of sharks. The more public support they have, the more they can do!

Oceana is campaigning to protect Great White Sharks with the help of actress January Jones. With the communities' help, the hope is to add great white sharks to the endangered species list in the California. You can learn more and sign the petition here.

NOAA Fisheries has a plethora of shark related information easily accessible on there website in response to shark week. Including a live chat on twitter Thursday August 8th at 2pm EST. You can tweet your questions to NOAA scientists at @NOAAFisheries and join in on the fun. 

Additionally our own Rainy Day Kit, "Sustainable Matching Game" can provide all ages with an introduction to sustainability in fisheries.

For your enjoyment, here is a "Symphony of Sharks" from NOAA Fisheries.