Wintering White Sharks: possible migrations along U.S. east coast

A possible migration corridor has been identified for great white sharks on the east coast of the U.S. A satellite tagging study was initiated in the fall by the Massachusetts Division of Marine Fisheries and some of the early results are intriguing. It is possible that the great white sharks that appear off the New England coast during the summer months - suspected of feeding on seal populations there - travel south during the winter months based on the results of a tagged shark who has appeared as far south as Jacksonville, Florida.

Satellite tagging has been used on great whites and other shark species to record location, speed, depth, and ambient temperature. Typically, a well-placed tag will record data for 30 to as long as 90 days then release itself, float to the surface, and download its data to satellites overhead. Researchers must wait patiently then sift through a mountain of data when it is downloaded all at once. Satellite tags can provide more long-range data than regional telemetry tags (like those documented in my film, Island of the Great White Shark) but are also subject to being dislodged prematurely. A newer technique, SPOT tagging, bolts the tag to the shark to insure a significantly longer monitoring period, but requires that the shark be caught and brought on board; a technique that has raised considerable controversy because of the physical impact imposed on the shark during the procedure.

In the summer months, several species of shark inhabit the New England coastline, from basking sharks to thresher and blue sharks to the great white white (although not in significant numbers). This new tagging study is the first indication that, like their distant cousins throughout the world who exhibit distinct migratory patterns, white sharks could very well be moving up and down the east coast based on seasonal temperature changes and any changes in prey populations that those seasons impose.

Great whites have already been shown to migrate from the west coast Farallon Islands to the mid-Pacific; same for the white sharks at Isla Guadalupe. White sharks have been monitored moving from South Africa all the way to Australia and back. While there can always be the occasional exception, there is continuing evidence that these sharks and other pelagic species develop critical migratory patterns. Our concern would be, what would happen to these sharks if their migrations were intercepted by commercial fishing fleets? Or what would happen to the overall health of their populations with changes in ocean temperature due to global warming? How ingrained are these patterns and what would happen if external factors were altered - could the sharks successfully adjust?

White Sharks at Cape Cod: keeping the news in perspective

It was about a week ago that several shark blog sites, like SharkDiver's, started to post news about a congregation of white sharks appearing off Cape Cod in the northeastern U.S. While white sharks are not unheard of in this area, the higher than usual numbers were of interest - a statistical anomaly or evidence of a population increase (wouldn't that be nice, given their decline in numbers over the years)?

Scientists want to tag as many sharks as possible with satellite tags to hopefully accumulate data that might explain the concentration. And of course the media wanted to report this as another harrowing intrusion of malevolent ocean predators upon society. This morning, NBC's Today show reported on the efforts of the lead researcher and while their reporting was fairly even-handed (better than it has been in the past when it comes to sharks), they still referred to the scientist as a "shark hunter" rather than shark researcher or tracker. It's subtle but the title still invokes a man vs. man-eater image.

This past Wednesday, the Boston Globe reported that the spotter pilot who was assisting the researchers in locating and tracking the sharks claimed that several sharks made distinct threatening movements when a diver or surfer entered the water, as if to imply that the sharks were on the hunt for humans and as soon as a person entered the water the shark suddenly knew exactly where to go and what it would find. Here's a portion:

“They definitely knew they were out there,” Breen [the pilot] said of sharks sensing the swimmers. “Whether they’d bite them, I don’t know.”

Breen was hired to help the research team, which tagged three great whites on Tuesday, bringing to five the number of sharks tagged with tracking devices over the last week. The discovery of sharks off Chatham forced the indefinite closing of the town’s beaches, but some ignored warnings not to swim in the area.

In one near-miss, Breen said he watched as a shark approached a diver from a documentary crew making a film about the researchers. He said he was circling above the filmmakers’ boat when the diver jumped into the water to retrieve a piece of equipment.

“I saw a shark going real slow about a quarter-mile away, and then when the diver jumped in, all of a sudden I saw the shark head right for the boat, going from about 2 knots to 10 to 15 knots, in an instant,” Breen said.

He radioed the crew on the boat and told them to get the diver out -- right away. The diver was attached to a tether and he was pulled out.

“The shark definitely smelled something,” Breen said. “Their sensory perception is unbelievable. The shark was only about 100 feet when they pulled the diver out.”

I know, for those of you who know anything about sharks, you're doing a slow burn right now. Sharks don't "smell" people in the water, particularly at a quarter-mile away! A white shark has pretty good eyesight, but not that good. No, it's the shark's ability to "hear" or sense vibrations in the water (a trait shared by nearly all fish) that caught its attention as the diver jumped into the water. And these animals are naturally curious. I have been fortunate to have several close encounters with white sharks and these events came about not because I was the meal d'jour but because my presence peaked its curiosity; I was something out of the norm.

Sharks like the great white have a battery of sensory capabilities that, based on distance (far away to close) typically react in this order: vibrations/sound (lateral line and inner ear); smell; eyesight; electrical impulses (Ampullae de Lorenzini); and finally, taste.

If Breen had spoken with the research team who hired him before speaking with the press, he would have been set right and his sensationalistic story could have been diffused. But if you're looking for a hot story or a little attention, what good is that, eh?

Some of the beaches in the area have been closed which, dramatic as that may seem, might be prudent for a short while. The sharks are in an area with a seasonal breeding population of seals, which is probably what has attracted them. That there might be a slight uptick in the highly remote possibility wherein a swimmer could accidentally be mistaken for a seal - particularly if the swimmer is wearing a black wetsuit - may be sufficient reason to close a beach temporarily.

But let's hope that it doesn't inspire sportfishermen or even government officials to go on some wild hunting safari to clear the area of an animal who has more right to be there than we certainly do.

Right Whales and Lobsters: lobstermen working to protect endangered whale

In addition to the Shark-Free Marina Initiative gaining a foothold in the northeast, the Ocean Conservancy is reporting progress with lobster fisherman in developing techniques to better protect whales, particularly the highly endangered Right Whale, from entanglement in their fishing lines.

Fisherman from Maine to Massachusetts are finding it benefits them in terms of overall cost efficiency to use fewer traps (greater yield vs. the cost to service/maintain). They are also switching to sinking rope that connect the traps, rather than the floating rope which was used in the past and posed a hazard to the whales. And there are more steps being considered.

The right whale population, hunted extensively off the New England coast until about 65 years ago, now numbers only about 400 individuals. They are one of the most endangered marine mammals on the planet. Yet, while no longer a target of harpoons, two human activities continue to pose major risks. The first is ship strikes. The second risk is entanglement in fishing gear, especially the heavy lines of lobster gear.

"The steps that Massachusetts lobstermen have taken are an important start to getting endangered whale populations on the road to recovery," said Vicki Cornish, vice president of marine wildlife conservation at Ocean Conservancy.

"The Massachusetts lobstermen have stepped up to the plate and been proactive in their participation," says lobsterman Mark Ring. 'We didn’t always all agree, but we are doing as much as we can do to protect these whales."

Bill Adler, executive director of the Massachusetts Lobstermen's Association, echoed the sentiment, saying, "We are the first in the nation to take important steps to protect whales with our fishing gear. We hope to set an example for other fisheries along the East Coast."

Read entire Ocean Conservancy article.