How to Grow a Bigger Brain

Hatchery-reared steelhead trout show increased growth of some parts of the brain when small stones are scattered on the bottom of their tank, according to a new study by researchers at UC Davis. The brains of those young fish were closer to those of salmon reared in the wild, and the fish also showed behavior closer to wild than to hatchery-reared fish.

"There's an obvious difference between the hatchery and the wild fish," said graduate student Rebecca Kihslinger, who carried out the study with Gabrielle Nevitt, professor of neurobiology, physiology and behavior at UC Davis. "A simple change affected brain growth in a large-scale way."

The results could affect the design of hatcheries for breeding fish to restock wild populations, Kihslinger said. The study is published in the February 2006 issue of the Journal of Experimental Biology.

Wild steelhead lay their eggs in gravel nests on the riverbed. After hatching, the fry, called alevins, stay among the gravel and live off their yolk sac until they emerge as free-swimming fry. In hatcheries, the fish are reared in tanks of clean, well-aerated water, but without environmental features or enrichment.

Earlier work by Nevitt's lab at UC Davis and other labs has shown differences between hatchery-reared and wild fish, Kihslinger said. But most studies have looked at older fish, and have not distinguished between the effects of selective breeding for "domesticated" fish and of the environment in which the fish live.

Kihslinger reared steelhead in regular tanks and in tanks scattered with small stones. She videotaped the fish, and measured the size of their brains after 10 to 12 days, when the fish were emerging as free-swimming fry. She also studied fish reared in natural conditions in rivers.

Fish reared in both sets of tanks had brains of similar size, but the cerebellum, a part of the brain that controls movement and body position, was significantly larger in fish reared with stones. Those fish also moved around less, perhaps using their yolk reserves more efficiently.

Fish reared in the river had larger brains than either group of fish reared in tanks, but the relative size of the cerebellum compared to the rest of the brain was about the same as in fish reared in tanks with stones.

Source: UC Davis

Related stories:

Scientists say they've discovered bacterium that will fight invasive mussels
Researchers seeking to slow the spread of invasive zebra and quagga mussels in American lakes and rivers have found a bacterium that appears to be fatal to the problematic species without affecting native mussels or freshwater fish.
Invasive mussel confirmed in Utah's Electric Lake
(AP) -- Trouble-making zebra mussels have arrived in Utah. But not where they were expected to show up. Electric Lake is Utah's first body of water where the damaging, nonnative mussels have been confirmed, state wildlife officials said Wednesday.
Researchers hope radio-tagged salmon provide clues to migratory habits
A swarm of 6,000 bionic salmon has become the latest tool in an ongoing struggle to protect declining fish species in the Sacramento-San Joaquin Delta of California.
Bacteria stop sheep dip poisoning fish and bees
Bacteria can be used to break down used sheep dip, preventing bees and fish from dying because of soil and river contamination, scientists heard today at the Society for General Microbiology's Autumn meeting being held this week at Trinity College, Dublin.
Copper-bottomed guarantee for safe shellfish in restaurants
Putting brass where your money is could be a guarantee of safety according to researchers looking at the dangers of eating raw fish and shellfish in seafood restaurants, scientists heard today at the Society for General Microbiology's Autumn meeting being held this week at Trinity College, Dublin.
Female fish see right through false suitors' pickup acts
In a dark, damp corner of a University of Wisconsin-Madison laboratory, Jenny Boughman dropped a 3-inch, three-spined female fish into a fish tank, and waited. She sat perfectly still as she watched a male fish swim out slowly from its nest, beneath a cracked flower pot.
Diversity among parasitic wasps is even greater than suspected
A tiny wasp that lays its eggs under the skin of unwitting caterpillars belongs to one of the most diverse groups of insects on Earth. Now researchers report that its diversity is even higher than previously thought.
Signals from the Atlantic salmon highway
For years scientists have struggled to understand the decline and slow recovery of Atlantic salmon, a once abundant and highly prized game and food fish native to New England rivers. Biologists agree that poor marine survival is affecting salmon in the U.S. and Canada, but specific causes are difficult to determine in the ocean. Small acoustic tags and associated technology may provide some answers.

News discussion:

General Science news