What Killed the Basking Shark on New York's Long Island?

July 17, 2009

This week's footage of the 20-foot basking shark that washed up on a Long Island beach was disturbing for many of us to watch. Despite their imposing size, these large sharks are the gentle giants of the ocean.

(Image Credit: Chris Gotschalk)

I've seen them off the coast of Cape Cod and in U.K. waters, just passively filter feeding and, by their very presence, sending out a quiet message that all is OK in their corner of the marine environment for the moment. But the below footage obviously presents a very different picture.

So what did kill the shark? Read on to find out why its death has puzzled experts.

All sharks, from great whites to hammerheads, possess very effective immune systems. That's partly because normal shark life, even romance, can be deadly. During mating, some males will bite females, causing very deep wounds. Yet within a few months, wounds caused either by these love bites or some other source usually heal without even scar tissue left behind.

Until recently, it was even thought that no shark suffered from cancer. That's since been disproved, but cancer is still very rare in elasmobranchs. Their blood contains potent antibodies that may ward off viral instigators of certain cancers. Plus, their cartilage produces anti-tumor chemicals that prohibit the formation of blood vessels that can feed tumors. You won't benefit by consuming shark cartilage, so don't even consider that thought. But researchers are studying shark cartilage to see if they can replicate, and tinker with, the cancer-fighting chemicals so that the compounds will help humans.

Pollution is one of the few things that can wear down a shark's immune system. PCBs, dioxins, furans, mercury, arsenic, and cadmium are just a few that we've introduced into the shark's marine environment. Countless studies show how these pollutants, and more, biomagnify in larger species closer to the top of the food chain. Basking sharks certainly fit that profile, even though they feast on zooplankton, small fish and invertebrates.

I am therefore very curious to know what killed this poor shark off the coast of Long Island, and what toxic substances will be found in its body.

Here's how I prefer to see basking sharks: majestic and very much alive.

Comments

[Natalia]

Awww, we're ruining the ecosystem!! I had no idea the basking shark was harmless. That makes it even cuter that he's so big and so friendly!! (I prefer to see them like in that second video too.)

[Jen Viegas]

Agreed, Natalia. A lot of tourist groups offer "dive with basking sharks" opportunities, since these enormous sharks are so gentle.