Whale Beaching breakthrough

Author - Kim McDonald

The Sunday Times. May 10, 1998

Whales have been beaching themselves on shores around the world for thousands of years. Until the reason behind the unusual phenomenon is discovered, a lifesaving technique for the mighty mammals will not be perfected. But according to physicist Dr Ralph James, recent research by the University of WA has confirmed a theory about the cause of beachings. And in what is believed to be a world first, he is design­ing an underwater signal to stop the whales beaching. Ancient philosopher Aris­totle would have been in­trigued by the research. More then 2300 years ago he questioned the suicidal game of Simon Says, in which groups of whales followed the leader into dangerously shallow waters. Biologists, oceanographers and whale watchers have since studied the phenomenon, suggesting causes such as ESP mess­ages from the leader, para­sitic infestation and geo­magnetic anomalies. But Dr James claims recent research by the bio-acoustics branch of the physics department has finally confirmed and built on a theory first suggested in the Netherlands in the 1950s.

The gently sloping beach theory states whales that use their sense of hearing rather than sight to navigate through the water and cannot detect gradual shores. Their echo-navigation sys­tems work as a series of clicking noises which bounce off rocks, fish and other objects, returning to the whales as an echo. In much the same way we measure the distance of thunder, the echo gives the whales a mental picture of their surroundings — in­cluding the proximity, size, shape and even texture of nearby objects.

Research by Dr James and two of his students confirms that apart from facilitating the stranding, a gently slop­ing beach reduces the strength of the echo. The softened echo makes it difficult for whales to properly assess the pres­ence of shallow water. Their research also shows it is the principal common factor in almost all reported strandings. The results help explain why beachings continue to occur in the same spots, such as the South-West of WA, which has some of the highest incidents of re­ported standings in Aust­ralia.

Unlike previous studies, Dr James' research also links the whales' sonar navi­gation system to bubbles and foam generated by the wind, rain and surf. A mass of bubbles and foam close to the shoreline absorbs the echo, further destroying their sonar navi­gation system. Several days of struggling under these conditions can weaken the whales, making them even less likely to detect a gently sloping shoreline. This helped explain why there were so many whale strandings one week after a storm.

"Think of it as like driving a car," Dr James said. "If it's a bright sunny day there won't be any prob­lems. But if it's raining and you are tired, you are more likely to make a mistake. "The gently sloping beach is like a blind spot to whales."

In what is believed to be a world first, Dr James is working on a warning sys­tem to signal incoming whales of shallow water. A slightly different system being developed in Europe intends to keep dolphins away from tuna nets.

"The design will be like an underwater foghorn moored about 100m from the shore, three or four metres," he said. "It will have its own sensor sonar that will emit a noise signal every hour to judge the "visibility" of water in terms of how the whale might visualise it. If the situation is danger­ous, it will send signals every 10 minutes or so to warn the whales," he said.