Following fantastic fish
2. Turning turtle
3. To track, to conserve
Hammerhead photo: NOAA
A large nursery for blue whales was just
discovered in Chile. The movement of large sea animals is still
an area of darkness, but new tracking systems are shedding light
on their wanderings. NOAA
Tracks from Laysan (yellow) and black-footed
(red) albatrosses criss-cross the North Pacific. Courtesy
Scott Shaffer and TOPP
no backpack. The harness replaces glue, which won't hold a satellite
tag to the leatherback's leathery shell. Here, scientists attach
tags to sea turtles that visit Monterey Bay in August and September,
looking for a mouthful of peanut-butter-and-jellyfish. Photo:
Monterey Bay National Marine Sanctuary.
tuna flies above the ocean and dives. A pod of whales surfaces, gulps
air, and disappears. A sea turtle breaks through its egg, scrambles
into the surf, and is gone. An albatross soars above the swells on
a remote reach of the South Atlantic. Aloft, at sea, for 11 months
a year, it circles Antarctica in its search for dinner.
How little do we know about marine life? Consider
the discovery in Chile of a nursery for blue whales, the largest
animal on Earth, just last year. Hunted by whalers almost to extinction,
the blue whale is slowly recovering. About 1,400 live in the Southern
Finding the nursery was a shock, ecologist Rodrigo Hucke-Gaete, of the Universidad Austral de Chile, told BBC News Online. "It was amazing to discover something like this in 2003. One thinks this is not an era of discovery, but we still have much to learn."
While earthbound ornithologists can espy their quarry with binoculars and track them with radar and leg bands, and mammologists travel to remotest Asia to study the residents of Earth's distant corners, marine scientists are still trying to answer one simple question: Where are the critters?
"Believe it or not, we don't know where they are, even in the 21st century," says Barbara Block of Stanford University. Traditionally reliant on eagle-eyed, sometimes seasick observers and numbered tags placed on a few animals, ocean biologists have seized high technology to answer basic questions about ocean animals.
Now, sophisticated electronic tags (Block calls the mix
"fish and chips" for its hybrid of fish and microchips) have started
spewing a flood of data on the lifestyle and migration habits of
the obscure objects of marine biologists' desire.
Marine organisms, it turns out, tend to congregate and move much like terrestrial ones. Where there is food, there are grazers, and where there are grazers, there are predators. "It's comparable in terrestrial terms to the Serengeti watering holes," says Block.
Modern electronic tags, some no bigger than a pen, store data and broadcast it to satellites. On air-breathing animals, the tags send data when they are above water; fish tags eventually release themselves, rise to the surface, and dump data. Often, researchers try to remove tags if they cannot be designed to release themselves.
An elaborate electronic tag can store 2 to 32 megabytes
of data on water pressure, light level, ocean temperature and body
temperature. Water pressure reveals depth, while light levels are
correlated with sun position and time of day to pinpoint location.
"It gives a complete picture of behavior as the animal moves through
the water column, give a picture of its interaction with the environment,"
Block is a leader of Tagging of Pacific Pelagics (TOPP) project, which is tracking 22 species of fish, mammals, birds and reptiles through the Pacific Ocean. TOPP is one of several pilot research projects under the Census of Marine Life, a decade-long, international collaboration to understand life in the oceans. (The census, which extends far beyond tracking, has recently compiled a list of 15,304 ocean fish species.)
The result is nothing short of a revolution in the science of finding fish -- and marine mammals, turtles and birds. "The vast majority, especially if they are submerged for most of their lives, are completely invisible," says Randall Kochevar, head of science communications at TOPP and at the Monterey Bay Aquarium. "With the electronic tags, we can get a real animal's eye view of what their life is like. Day by day, season by season, we can begin to see the whole pattern of their life."
The picture becomes more complete when position data are
correlated with other information on ocean conditions, derived largely
from satellite. Suddenly, it becomes possible to answer intriguing
questions about not just where organisms go, but why they go there.
This graph shows crashing sea turtle populations
on Costa Rica's most important nesting beaches, which are among
the most important in the Pacific. The long-term nesting data from
these beaches serves as an index for leatherback population trends
throughout the Pacific. Courtesy Sea
Turtle Restoration Project
The sea looks "featureless and trackless," says Elliot Norse, president of the Marine Conservation Biology Institute, but the new data show that "the ocean is anything but homogenous. The big organisms, the big fish, the billfish [swordfish and sailfish], the tuna, pelagic [open-water] sharks, the marine mammals, the great wandering birds, like albatrosses, key in on certain features in the oceans ...where masses of water come together and create conditions they especially like. They commute among these places, behave almost as if they are on highways in the sea."
Norse hopes the new information will be used to design temporary reserves, where endangered organisms would be protected -- but only when they need protection. Industrial fishing fleets, he says, have pushed one prized prey after another to the vanishing point.
Ready to track turtles across the open sea?