Biology students are simulating a river at Fresno State to conduct key fish studies for the San Joaquin River restoration.

The students are circulating water through large, aquariumlike tanks, mimicking the flow of a natural stream while they research the best ways to raise robust salmon.

The research is timely because salmon will be returned to the river in late December 2012. State wildlife authorities say the fish probably will be raised at a hatchery. But such fish sometimes do not fare well in the wild, so officials sought research help from the university.

"Survival for these fish can be quite a challenge," said environmental scientist Paul Adelizi of the state Department of Fish and Game. "We want as many minds involved as possible on this project."

Salmon restoration is a cornerstone for the San Joaquin project, considered one of the nation's most extensive river renovations.

After Friant Dam was built in the late 1940s, about 60 miles of river dried up and chinook salmon runs died.

The restoration -- the result of a 2006 agreement to settle an environmental lawsuit -- reached a major milestone this year when federal officials reconnected the river with the Pacific Ocean.

Salmon swim to the ocean to live most of their lives and then return to their home river to spawn. But they will need more than a continuous flow of water.

Dams must be bypassed along the way and the river channel must be widened or deepened in some places. In addition, the exact route through the Valley's west side still must be determined.

Fresno State entered the picture this year when Fish and Game suggested a partnership to study salmon. The state provided the two 900-pound water tanks to study fish.

The water is circulated and chilled to the proper temperature in the tanks to simulate a river flow. The water also is filtered through charcoal to help remove the fish wastes and keep them healthy as they grow.

When they're inserted into the tanks, the fish still have yoke sacs that feed them as they mature.

For the first experiment, biology students, such as Monique Chavez, 26, and Kong Vang, 23, are using rainbow trout, which share the same family as salmon and react in similar ways.

They are asking a simple but important research question: "Are there lower survival rates when fish are not raised on clean gravel beds like the ones you see in the wild?" asked student Chavez.

Biologists say recent research indicates flat, smooth surfaces in hatcheries don't work as well as gravel beds for young salmon.

Hatchlings must use a lot of energy just to maintain balance on flat surfaces because there is nothing to keep them upright. The result, biologists say, is probably a smaller, weaker fish.

If the hatchlings can wedge themselves into the small gravel, they probably will grow larger and stronger.

Fresno State students, along with professor Steve Blumenshine, have provided both environments for two groups of developing fish.

They will compare the weight of the two groups, Blumenshine said. The weighing device will record fish weight all the way down to one-thousandth of a gram, he said.

"This is a great hands-on experience for the students," he said. "The students had to build parts of the tank for this experiment. This is what researchers do."