DNA detective work unveils Korean "bycatch whaling"

Another news bite from New Scientist (by Peter Aldhous):

"DNA detective work has revealed that fishermen in South Korea are snaring far more whales in their nets than they admit. The "bycatch" is so large that some observers believe whales are being netted deliberately, breaking the moratorium on commercial whaling set by the International Whaling Commission (IWC).

Whale meat can be sold legally in South Korea if the animals are caught by accident in fishing nets, but such deaths must be reported to the government. Between 1999 and 2003, fishermen reported snaring 458 minke whales. Now a team led by Scott Baker of Oregon State University in Newport says the true catch was nearly twice that number and threatens the survival of minke whales in the Sea of Japan.

Baker had South Korean colleagues buy minke meat from local markets and used DNA fingerprinting to determine how many individual whales the meat had come from. That alone did not reveal the total number of whales caught; the researchers calculated that figure by borrowing a technique called "mark and recapture". Ecologists estimate the size of an animal population by trapping, marking and releasing animals, and then seeing how many marked and unmarked animals turn up in subsequent trapping efforts. Using the DNA signatures of individual whales as markers, successive surveys revealed population data for the dead whales whose meat was being sold in the Korean markets.

With the aid of a mathematical model developed by Justin Cooke of the Center for Ecosystem Management Studies in Gutach, Germany, Baker's team estimated that South Korean fishermen caught 827 minke between 1999 and 2003 (Molecular Ecology, DOI: 10.1111/j.1365-294X.2007.03317.x). "This is a very exciting study because it finally provides a tool to establish the magnitude of the bycatch problem," says Phil Clapham of the US National Oceanic and Atmospheric Administration's Alaska Fisheries Science Center in Seattle.

"We suspect this is really a form of unregulated commercial whaling," says Baker. Given that a single minke whale can fetch up to $100,000, there is a strong financial incentive for fishermen to entangle whales in their nets.

Baker's team was also able to show that the average "half-life" of meat from an individual whale in South Korean markets is 1.82 months, suggesting that surveys to monitor for illegal meat should be conducted about every two months. Baker's project was backed by the International Fund for Animal Welfare and Greenpeace International.

The South Korean government has shown little enthusiasm for launching a monitoring programme of its own. Japan, meanwhile, has rebuffed attempts to discuss meat surveys at previous IWC meetings. The IWC meets later this month in Anchorage, Alaska.

Minke whales in the Sea of Japan are the subject of an ongoing IWC review. "This population is clearly in trouble," says Clapham, who is a member of the US delegation to the IWC. "It is being hit from Japan and Korea by bycatch, and probably by deliberate take."

From issue 2603 of New Scientist magazine, 10 May 2007, page 10

Fly your ROV as smoothly as a fish

I found this article on "electro-receptive navigation" while gathering data for a presentation on "animal navigation". But as it turns out, technology is yet again trying to mimick natural adaptations, as the following article shows:

"Robotic and uncrewed submersibles could operate more effectively by mimicking the way some fish probe their surroundings with electric fields, say researchers.

Many marine and freshwater fish can sense electric fields, but some also generate their own weak fields over short ranges to help navigate, identify objects, and even communicate with other fish.

"Currently, no vehicle is manoeuvrable enough to do work in tight quarters, such as coral reef monitoring, underwater structural inspection, or searching a submerged vessel," MacIver told New Scientist. "To do so requires not only a high amount of agility, but also being able to sense in all directions, so that you do not collide with nearby obstacles. Electro-location is perfect for this."

The researcher's electro-location system consists of two field-emitting electrodes and two voltage-sensing electrodes. These electrode pairs are arranged at opposite corners of a diamond, and were submerged in shallow water for testing purposes.

If the electric field is not disturbed by anything in the water, the two pairs of sensor electrodes should provide identical readings. But if something is placed within a few centimetres of the sensors, the field is disturbed and causes a variance in the sensor readings.

Since the position of the object affects the way the electric field is disturbed, a computer can use a series of sensor readings to determine the object's location. It is even possible to detect small objects by amplifying subtle perturbations in the field.

MacIver believes compact, agile submersibles could one day be covered in many electro-sensors - although he notes that weakly electric fish use many thousands. So the next step, he believes, is to develop an array of sensor electrodes and attempt more complicated tests.

Steve McPhail, who designs autonomous underwater vehicles at the UK's National Oceanographic Centre, part of the University of Southampton, also sees potential in the idea. "It sounds like this would be useful for small, agile subs operating close to the seabed or in tight spaces," he says. "An obvious advantage is that the sensors are quite cheap."

MacIver admits that it will be a long while before electric field sensors are anywhere near as sophisticated as those found in nature. "It has taken the machine vision community many years to 'teach' computers how to perceive simple objects using light," he notes. "We are just starting the process of understanding how to perceive simple objects using 'electro-sense'."

(Source: NewScientist.com)

I just wish they already had these sensors in place, since my dream of an "under-ice ROV" would also need this tight-quarter manoeuvrablility...