Thursday, August 30, 2012

Whale eyesight & other things

My schedule doesn't allow me to get out to as many Maine-related talks and lectures as I'd like, but every now and then I manage to squeeze one in. Earlier in August, I was lucky enough to make it down to the Gulf of Maine Research Institute, where Dr. Scott Kraus (of Boston’s New England Aquarium)was holding a presentation about "What Do Whales See?" The talk was well-attended, to the point of being standing room only.

John Annala, Chief Scientific Officer for GMRI, gave an introduction in which he emphasized GMRI's focus on sustainability in the Gulf of Maine, as opposed to an approach focused on locking up resources or “preserving” them. Their goal is to increase collaboration across the board, and their current education program has successfully accomplished outreach to an impressive 75% of Maine's 5th and 6th graders, every year giving school kids a look at GMRI's work no matter where they are in the state.

With that context given, Dr. Kraus took his place under the room's giant projection screen, and began his presentation. Back in the 1970s, he was hard at work with a group of scientists collaborating with local fishermen up in Newfoundland, where each year the cod box nets were accidentally netting humpback whales along with the cod schools. No one could figure out why such a huge, obvious structure was being run into by the whales. By all reasoning, they should have been able to sense them in the water, but instead, hundreds of whales were running into them every year, many of them becoming entangled in them with disastrous results for both the whales and the nets.

His team had begun by zipping around disentangling the whales whenever the fishermen sent out an alert, and while they were doing this, they were studying the whales’ behavior. They were perplexed to find that when the whales were trapped, they did not emit any sounds of alarm to broadcast their distress. By 1975 it was obvious to the scientists that something odd was going on. Could it be that these baleen whales didn't use sound the same way as other whale species, including the generation of sonar by which to navigate?

To answer that question, the scientists rigged up a maze in an ideal spot at the base of a Newfoundland cliff where they could observe from above. This was going to be the first time anyone had done any sort of test of whale eyesight limits.

The next time a good subject whale was disentangled from a cod box net, it was transported to the maze test site and fitted for blindfolds. As you can imagine, this was a time for revving up their creative problem solving skills, because the irregular shape of a whale's head demands a unique design for effectiveness and comfort. They also had to take into account the mammoth dimensions of the whale's eyeballs, each the size of a grapefruit.

The scientists wound up using a pair of eyepatches, giant in size. The edges were lined with foam cushions, which served to block accidental visibility as well as giving a comfortable fit to the whale's contoured eye area. Large suction plungers were utilized to attach the eyepatches.

With them in place, the scientists ran a variety of trials, 33 attempts in all. At no time did the whale ever use sonar! The only time the whale successfully ran the maze was when it was given use of its eyesight in daylight. The only exception to this was one nighttime trial when they were attempting to use a flashlight attached to the whale's tail to give the observing scientists on the cliff overhead an accurate sense of where the whale was in the maze.

It turned out that the flashlight gave enough visibility to the whale to allow it to correctly navigate the maze. Needless to say, they had to find another solution for the observers. They wound up stationing them at each point of the maze, where they could see the whale's movement through the water well enough to determine its success.

At the end of the trials, they set their humpback subject free, and went back to the drawing board with the new information that baleen whales didn't use sonar. They were capable of using their hearing for long distance navigation, and recognition of heavy traffic shipping lanes in the water, but otherwise they depended fully on their eyesight, with no recourse to echolocation.

That eyesight is in the green to blue spectrum, suitable to deeper water. This gave the scientists a new source of perplexity, because the copepods that the whales were using as a primary source of food were red in pigmentation, a color which eluded the whales' sight limits. Further exploration determined that the whales could see the copepods as lightblockers, and this allowed them to locate them in the water for feeding.

The scientists, still experimenting with options that would make the cod box nets visible to whales in spite of their limited eyesight, began a series of trials to determine the best color with which to coat the nets for high whale visibility. Using what they had learned from the copepod coloration as a starting point, all sorts of lines were tried, from the typical green, white and black lines of current fishing practice to glow in the dark lines, to LED-lit lines.

The whales ran right into the white, green, black and glow-in-the-dark lines. On the other hand, they responded consistently to ropes that were red and orange, turning aside in time to avoid them. The glow-in-the-dark lines presented insurmountable problems for the fishermen anyhow, as their luminescent nature attracted algae growth in the dark depths. Anytime sub-aquatic growth accumulates, hauling ropes becomes a problem, as the growth fouls the lines as they’re being drawn up into the hauling mechanism on the fishing boat.

[PHOTO: Brian Murphy cleans algae and other growth from the trapline of the Blue Dolphin II. Every time the traps are hauled up, the buoy line needs to be cleaned to prevent overgrowth and fouling of the line. The barrel has a heating coil, and with the steaming hot water and a stiff scrub brush, the overgrowth is brought under control until the next time. The growth occurs because the buoy line is close to the surface, where sunlight encourages all sorts of species of salt water plants and animals to flourish. Photo by Michelle Souliere, (c)2010]

The LED lines had technical problems on two fronts – power supply and durability. In the end, Dr. Kraus was unable to find existing LED rope structured durably enough to survive going through the sheaves of a hauler, and, as he observed in response to my inquiry via email, “the implantation of any LED within existing ropes turns out to be extremely difficult -- others have tried embedding radio frequency PTT tags in ropes with poor success.” (PTT= Platform Transmitter Terminal tags= radio-frequency transmitters used to enable satellite tracking of animals) It is entirely possible that even if the LED ropes had worked well enough, and had generated a positive response in the whales’ navigation, their luminosity may have been problematic in generating growth on the fishing lines, as had been the demonstrated tendency of the glow-in-the-dark lines during testing.

It should be noted here that throughout the tests, local fishermen have assisted Dr. Kraus's team, ensuring that the eventual solution will work on a practical level as well as theoretical. The next series of usability tests is made possible by the participation of members of the Maine Lobsterman Association.

Progress is slow without the ability to communicate directly with the whales. Each conclusion must be made through simple, regulated observation and slight changes in conditions to observe differences in behavior. Still, each year they get closer to making the heavily fished offshore areas of the Northeast safer for the often endangered whales who also call these regions home.

If this sort of stuff piques your interest, why not check out the Gulf of Maine’s Sea State Lecture Series? The lectures are free and open to the public, and are held at the GMRI’s facility in Portland, at 350 Commercial Street. For more information, contact Patty Collins at
(207) 228-1625 or via – or simply sign up for email updates on their website at

1 comment:

Michelle Souliere said...

Dr. Kraus just presented his updated findings to the audience at the annual Maine Fishermen's Forum! Story via