Dolphin declines linked to panic swimming

[United Press International]

HAIFA, Israel, May 4 (UPI) -- An Israeli researcher is
building evidence tuna fishermen are responsible for baby dolphins
becoming separated from their mothers and dying.
Daniel Weihs, an aerospace engineer at Technion, the Israel
Institute of Technology, has modeled the complex hydrodynamic
interactions between two dolphin-shaped objects traveling through
water.
Young dolphins keep up with their mothers by adopting a
position to get a "free ride" in the mother's slipstream, according
to an article published this week in the "Journal of Biology."
Sudden fleeing from fishing boats is likely to disrupt the
positioning of mother-calf dolphin pairs, causing the younger
dolphins to get permanently separated from their mothers.
In the ideal position, the mother can provide close to 90
percent of the thrust needed for the young cetacean to move at
around 5 mph.
Weihs' findings could help explain why the dolphin
population of the Eastern tropical Pacific Ocean has not recovered,
despite recent restrictions on purse-seine tuna fishing. Fishing
that took place prior to the restrictions may have disrupted dolphin
schools, causing many younger dolphins to die before they were able
to breed.