Frankenstein's Cat: Cuddling Up to Biotech's Brave New Beasts (14 page)

Surgically implanted tags can cause pain or lead to infections, while external ones can cause sores; biologists have documented cases in which the harnesses used to attach transmitters to sea turtles caused abrasions and tissue damage. Tracking devices can also attract predators, alter an animal’s social status, or make it less desirable to potential mates. Poorly placed tags can snag on trees or brush and interfere with an animal’s ability to swim, walk, or fly. Simply being caught and handled by humans can be traumatic, causing spikes in heart rate, respiration, body temperature, and the production of stress hormones, and leave animals susceptible to various diseases and pathogens.

These possibilities are problematic for animal welfare reasons, but also for scientific ones. We’re tracking animals to learn more about them, and if the tag itself alters behavior, physiology, or survival, the data will be distorted, if not totally useless. So biologists who want to minimize the effects of tracking devices have to carefully consider countless variables. They must think through the physical and behavioral characteristics of an animal when deciding what kind of tag to use, where to place it, and how to attach it. Where, when, and how an animal is caught, restrained, handled, and released also matter. Some tags may be totally innocuous—for every study documenting the devices’ adverse effects, there’s another that shows tagged animals doing just dandy—but an ill-conceived one could be a death sentence.

It’s not easy to perform controlled, long-term studies on how tags affect animal welfare, since it’s difficult to get data on untagged animals as a point of comparison. So Block and her colleagues have tested out different tag shapes, attachment strategies, and surgical techniques with captive tuna. They implanted archival tags in tuna living at the TRCC and monitored the fish for months. The wounds healed well, and the only noticeable side effect was some “minor irritation” where the light-sensing stalk protruded from their bodies.

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For all the discussion of how tags can harm animals, there’s not much talk about how such devices could benefit them. Exhibit A: TurtleWatch, a program designed to protect loggerhead turtles, the giant, long-lived reptiles classified as “endangered” or “threatened” in the Pacific, Atlantic, and Indian oceans. The loggerheads that live in the northern Pacific nest in Japan and Australia but make yearly migrations across the open ocean, using their brown-and-white speckled flippers to paddle their way to the shores of the Golden State. Though the turtles aren’t commercially harvested, they can swallow hooks or get tangled in lines set out by fishermen.

This “bycatch” of loggerheads is a problem for both the turtles and the fishermen. Federal regulations stipulate that the longline swordfish and tuna fishery operating around Hawaii cannot accidentally hook more than seventeen loggerheads annually. That’s a collective total for all the boats working in the area—after someone snags the year’s seventeenth turtle, all the fishermen must return to shore for the rest of the calendar year. In 2006, the fishery reached this limit unusually early—in March—and had to cease operations until the next year.

After that season, which was catastrophic for the fishing industry, Jeffrey Polovina and Evan Howell, both oceanographers at the National Oceanic and Atmospheric Administration Pacific Islands Fisheries Science Center, established TurtleWatch to reduce the turtle bycatch. Polovina, Howell, and their colleagues had already used satellite transmitters to track young loggerheads, and they’d discovered that the reptiles preferred water in a narrow temperature range: between 63.5 and 65.5 degrees Fahrenheit. The loggerheads also spent most of their time cruising around a region of the Pacific where large systems of marine currents converge; all sorts of buoyant, gelatinous critters pile up amid this churn and swirl of seawater, providing easy pickings for hungry turtles.

Polovina and Howell decided to use this information to predict where turtles might be on a particular day and encourage fishermen to avoid that area entirely. Since December 2006, that’s what they’ve been doing under TurtleWatch. Every day, Howell examines the latest data on sea surface temperature and ocean currents and produces a map of the fishing grounds, using thick black lines to mark off regions where conditions will be especially turtle-friendly. The maps, which are produced in English, Vietnamese, and Korean, advise fishermen to avoid setting their lines in these areas and are dispatched daily to fisheries managers and individual boats. Since the program began, the fishery has never hit its maximum number of loggerhead encounters.
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The TurtleWatch approach doesn’t make sense for species that fishermen
want
to catch, such as tuna. But there are ways that we can use tracking data to help protect the overexploited tuna populations. Since the early 1980s, fishermen have been subject to strict quotas; the International Commission for the Conservation of Atlantic Tunas (ICCAT) sets limits on how many pounds of bluefin can be pulled out of the water each year. ICCAT manages the Atlantic bluefin population by literally drawing a line down the middle of the ocean and treating the fish on each side as a distinct population. To the west of the line are tuna that breed in the Gulf of Mexico, while the eastern population breeds in the Mediterranean Sea. The western population, which has declined by more than 90 percent since 1970, is much smaller than the eastern one, so the quotas on the American side of the Atlantic are much more stringent.

It’s a reasonable system, provided the fish stick to their side of the ICCAT line. “Well, when we started tagging and tracking bluefin tuna,” says Randy Kochevar, the Stanford marine biologist, “one of the first things we realized is that nobody told them about this line down the middle of the ocean.” Kochevar works in Block’s lab, where researchers have been following the trails of Atlantic bluefin for more than a decade. Their tracking data reveals that in the spring and summer, the fish do indeed segregate themselves—a tuna born in the Gulf of Mexico will return to the Gulf to breed. During the rest of the year, however, the fish use communal foraging grounds spread across the Atlantic. And as soon as the western tuna cross over the invisible ICCAT line, they can be harvested at a much higher rate. This finding helps explain why western tuna populations aren’t bouncing back and points the way to better management plans. Block’s team, for instance, has suggested establishing a new ICCAT zone, in the shared central Atlantic foraging grounds, governed by a strict catch quota. In this way, data from tuna tracking studies could be used to craft fisheries plans that lead to real recovery.
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As marine tracking matured, oceanographers realized that they could piggyback on biologists’ tagging projects to learn about the sea itself. That’s what happened when Michael Fedak, a marine biologist at the University of St. Andrews in Scotland, started tagging southern elephant seals. The blubbery behemoths—males can weigh in at more than 4,000 pounds—spend their lives in one of the most inaccessible places on the planet, enjoying winter in the frigid Antarctic waters. Some of the deepest divers on Earth, the mammals can descend more than a mile beneath the surface to hunt for dinner. The seals spend a few months every year on the beach, where they molt and breed, but when they slip back into the water, Fedak says, “they might as well be going off to another galaxy.”

Eager to learn more about these seals’ habitats, Fedak outfitted the animals with tags that would measure the basic physical characteristics of the water in which they were diving. Between 2003 and 2007, Fedak and his British, French, Australian, and American collaborators glued multifunction tags to the hairy heads of 102 elephant seals.
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Whenever an elephant seal dove beneath the surface, the gadget whirred away, measuring the water’s pressure, temperature, and salinity at regular intervals. When the seal surfaced, the tag’s satellite transmitter sent the data back to the lab. According to Fedak, the sensors in the tag are essentially identical to those that oceanographers lower into the sea from a ship, “except stuck on something hairy and warm.”

In fact, as the numbers started trickling in, Fedak realized that oceanographers were eager to see the information his seals were collecting. “These guys needed this data for this much grander job of understanding how the ocean behaves,” he says. Oceanographers are now using the temperature, salinity, and pressure readings from the seals’ deep dives to construct detailed profiles of entire vertical columns of water. Because the animals routinely plunge under ice caps, where ships can’t navigate, they are illuminating parts of the planet that have, until now, been complete blind spots. Among other things, tagged elephant seals have revealed previously undiscovered troughs at the bottom of the Antarctic Ocean. These valleys, which can funnel warm water under ice caps, may explain why some ice shelves have been melting faster than expected. Today, marine mammals have collected 70 percent of the Antarctic Ocean data in the World Ocean Database, and the U.S. Integrated Ocean Observing System is working to incorporate data collected by all sorts of tagged swimmers into its models of ocean conditions.

Ice melt is just the beginning—global warming is raising water temperatures and levels, and changing its acidity and salinity. Experts are also predicting long-term changes in precipitation, storm frequency, and ocean currents and circulation. These shifts are already having profound effects on marine life. As waters warm, many species of fish are moving toward the planet’s poles, and there have been shifts in the distribution and availability of various nutrients and food sources, including plankton, the floating organisms that are central to many marine food webs. Scientists have, in turn, linked changes in prey availability to findings that porpoises are taking longer to mature, seals are giving birth later in the year, and whales are having fewer calves. Of course, some species are adapting to our warming world, but those that fail to adjust quickly enough could find themselves staring down the barrel of extinction.

Data from tagged elephant seals and other marine animals will help us monitor, forecast, and prepare for the drastic environmental shifts that threaten ocean life and predict what will happen to animals as the seas change. For example, scientists have used tags to estimate a seal’s buoyancy, an indirect measure of body fat. A fat elephant seal is a thriving, well-fed elephant seal, and by using buoyancy, location, and other tag data, scientists can construct maps of where elephant seals find food and what ocean conditions are like there. “We can then run models around where those kinds of places might be in the future and how far away they are from where animals might breed,” Fedak says. “It’s the beginning of asking questions about how oceanographic changes might affect populations, of saying, ‘Well, if things do shift … what will happen to the beasts?’” The latest generation of tags and sensors are turning elephant seals and other marine animals into more than scientific subjects. “We’re making colleagues of the animals,” Fedak says. “There really is an opportunity for us to understand the ocean not only for our reasons but for them as well. The animals and us are all in this together.”

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Tagging technology is advancing at a rapid clip, and tracking projects are proliferating. Several years ago, scientists launched the Ocean Tracking Network, a $168 million project based at Canada’s Dalhousie University. It’s a collaboration of more than two hundred scientists in fifteen nations that aims to follow the movements of thousands of marine animals, from seals to eels, all over the globe. The project relies on acoustic tags, which emit pulses of sound that can be detected by underwater receivers. The basic technology has been in use for decades, but the Ocean Tracking Network is taking it to the next level by installing arrays of underwater “listening stations,” capable of picking up the signals of any tagged animal that happens to swim past, along the ocean floor. The receivers, which are the approximate size of fire extinguishers, record the animal’s presence, upload any data that’s been stored in its tag, and relay the information to researchers. So far, OTN technicians have set up hundreds of these receivers on the seabed off the Canadian coast, with smaller deployments near Australia and South Africa. The goal is to establish similar arrays in all the world’s oceans.

New kinds of tags are providing even more detailed information about the daily lives of ocean animals. A team of Hawaiian biologists, for example, gave Galápagos sharks electronic “business cards,” acoustic tags capable of detecting other tagged sharks and recording when the predators encountered one another in the wild. Widespread use of these devices could help us learn more about how different individuals and species share the marine environment. A number of other labs are using tags that measure acceleration to determine when a shark is mating or a sea lion is hunting for fish.

Scientists who track deep-sea fish are beginning to deploy a second kind of device, known as a “pop-up” satellite tag, alongside their archival instruments. When attached to the outside of a fish, these pop-up tags collect and store the usual information about temperature, light, and depth. After a predetermined number of days, the tag automatically detaches from the fish and floats to the surface, where it sends its stored data to satellites. These tags are bigger, heavier, and more expensive than archival implants, and because of slow transmission speeds, they can transmit only small amounts of data. But prices and sizes are dropping, and the technology is being used on a variety of large fish, including swordfish, marlin, and tuna. (Barbara Block, who piloted the use of these devices with bluefin tuna, employs both pop-up tags and archival ones in her tracking studies.)

As electronic tags shrink to near invisibility, it’s becoming possible to track an ever-expanding menagerie of marine and terrestrial species. A Canadian company sells a radio transmitter that is smaller than a fingernail and is practically weightless, at 0.25 grams. In 2010, researchers reported that they had used miniature tags to follow iridescent orchid bees as they flew through the tropical forests of Panama, and a group of Swedish scientists have shown that we may be able to track the movements of water fleas (
Daphnia magna
)—millimeter-sized, freshwater crustaceans—by attaching fluorescent nanoparticles to their tiny little shells.