- News Home
5 December 2013 11:26 am ,
Vol. 342 ,
An animal rights group known as the Nonhuman Rights Project filed lawsuits in three New York courts this week in an...
Researchers have been hot on the trail of the elusive Denisovans, a type of ancient human known only by their DNA and...
Thousands of scientists in the Russian Academy of Sciences (RAS) are about to lose their jobs as a result of the...
Dyslexia, a learning disability that hinders reading, hasn't been associated with deficits in vision, hearing, or...
Exotic, elusive, and dangerous, snakes have fascinated humankind for millennia. They can be hard to find, yet their...
Researchers have sequenced and analyzed the first two snake genomes, which represent two evolutionary extremes. The...
Snake venoms are remarkably complex mixtures that can stun or kill prey within minutes. But more and more researchers...
At age 30, Dutch biologist Freek Vonk has built up a respectable career as a snake scientist. But in his home country,...
- 5 December 2013 11:26 am , Vol. 342 , #6163
- About Us
Easy Life Makes for Dull Fish
16 August 2000 6:00 pm
SNOWBIRD, UTAH--Anglers have long noted that compared with their wild kin, hatchery-raised trout and salmon do not seem to be very bright. According to research presented here last week at the annual meeting of the Ecological Society of America, they also have smaller brains.
Hatchery trout are known to grow faster and larger than wild fish, but to be less wary of predators, say aquatic ecologist Michael Marchetti and neurobiologist Gabrielle Nevitt of the University of California, Davis. To see if these differences were reflected in the fishes' brains, the scientists assembled two strains of hatchery-raised rainbow trout and two of wild fish. The team then took eight different measurements of the brains of the 48 wild and 51 hatchery fish.
For seven of the eight measures, wild trout had bigger brains. The telencephalon--the fishy equivalent of the cortex--was larger, as was the olfactory bulb. Marchetti suspects that as with mice--whose brains develop fewer connections when raised in austere environments--so with trout. Hatchery fish live in a bland and relatively stress-free environment, he said, whereas wild fish must contend with predators, changes in water velocity and temperature, and unpredictable edibles.
John Musick, a marine biologist at the Virginia Institute of Marine Science in Gloucester Point, Virginia, says that although hatchery-raised fish are known to have lower survivorship in the wild, no one had linked it to actual brain differences. "To see such gross differences--that's very surprising."
To see whether they are mostly the result of the environment interacting with the developing brain--as opposed to gradual genetic change in captivity--Marchetti and Nevitt now plan to compare members of a single strain of Coho salmon raised in either captive or wild environments. "We think there's a lot of implications of this work for captive rearing," says Marchetti, because restocking depleted streams with unfit captive-bred fish may be bad for wild populations, for instance. And captive trout fry, he suggests, may need more challenging environments.