Physiology Study Breakthrough : Large Fish to Hit the Treadmill for Research
A San Diego researcher has developed a device that for the first time will enable scientists to study the physiology of large fishes at sea, collecting information that observers hope may prove useful in commercial fishing and fisheries management.
The instrument, described colloquially as a water-tunnel treadmill, can be taken to sea on a research vessel and used for studying changes in blood flow, heart rate and oxygen consumption in large, fast-moving fishes like tunas, mackerels and some sharks.
That information may then suggest how environmental conditions, such as thermal effluents, affect the animals, and how human activities, such as off-shore drilling and underwater mining operations, alter distribution, productivity and survival.
The device “will meet a longstanding need of marine biologists and physiologists,” Edward Frieman, director of Scripps Institution of Oceanography, said Friday at the treadmill’s unveiling. “ . . . We regard this, basically, as a national resource.”
The so-called water-tunnel respirometer, developed over the Last seven years by Jeffrey B. Graham, a research physiologist at Scripps, is a sprawling contraption of pipes and chambers through which sea water is propelled at varying speeds.
A fish up to 40 inches long--three times the size of those currently studied--can be caught, attached to instrumentation, placed in the treadmill’s swimming chamber, and monitored by computer while researchers modulate the water’s speed, temperature and salinity.
“We have no knowledge of the hydrodynamics of fish greater than 40 centimeters,” Graham said Friday. He said devices have existed for studying small fishes, but there had been no way of studying large ones that swim deep below the surface and do not come up for air.
“Everybody wanted it, but they wanted it to be done right,” said Stephen Bishop of the National Science Foundation, recalling foundation officials’ criticisms of the device when Graham first presented it for funding. “And I think he finally did it.”
The treadmill is expected to reveal new information about the workings of cardiovascular systems, as well as providing data that may be useful to hard-pressed commercial fishermen and public officials seeking to regulate the nation’s fisheries.
For that reason, Assemblyman Larry Stirling (R-San Diego) turned up at the unveiling and expressed some optimism that the respirometer might eventually contribute to the development of state policy on protection and exploitation of fisheries.
He said he hoped that the technique might better enable commercial fishermen to understand and follow the movements of such fish as albacore tuna, while at the same time showing policy makers how best to protect the resource.
“Scientists have an interest in knowing the maximum sustainable yield, and of course the taxpayers have an interest in the yield being sustainable,” Stirling said. “So one hand washes the other. . . . Before you can say, ‘You can’t fish, fishermen,’ or, ‘You can fish,’ you have to know what the sustainable yield is.”
Graham, who said the idea of the respirometer first occurred to him as a graduate student in 1967, said the treadmill will undergo its first field tests in early June on a Scripps research vessel 15 to 100 miles off San Diego.
