There are over 1.5 million fish at the San Joaquin Fish Hatchery at the base of Friant Dam, which holds back Millerton Lake on the border of Fresno and Madera Counties.
Greg Paape runs the hatchery for the California Department of Fish and Wildlife. Today he’s inspecting the health of rainbow trout that he and his team have watched grow from eggs to four to six pounders.
“There’s a nice one there – you can see the rainbow color on him,” Paape says. “If he was in here by himself he’d be a lot silverier. Their he goes.”
This hatchery along with three others in the region are dependent on snow melt collected in the state’s reservoirs – like Millerton Lake. And the lack of snow has officials like Dean Marston concerned, not just with the amount of water, but also its temperature.
He’s an environmental program manager with CDFW who oversees 12 California counties. He says water temperatures are good at the moment “but as we get into the spring when temperatures start to warm and flows start to reduce then we might have to rethink how we are raising fish in our hatcheries and rethink where we’re planting the fish.”
The hatchery at the base of Friant Dam uses water pulled from the reservoir to regulate the temperature of six acres of fish runs and ponds.
Paape and I took a walk to feed a run of more than a thousand mid-sized rainbow trout.
“We don’t have any chillers or anything like that,” Paape says. “We can control temperatures to a good extent up at the dam. There’s a valve high in the Friant-Kern Canal and there’s a valve low at the bottom of the dam and it’s essentially as easy as adjusting your shower temperature you open one valve and close the rest and you can adjust your temperature higher or lower.”
Paape’s major concern is that if reservoir levels become too low at Friant Dam, Millerton Lake water will become warmer making it harder for fish to take in oxygen.
“We’ve never experienced a one year drought this drastic,” Paape says. “We’ve had one and two year droughts where each year was built on the one before, but this is the lowest water year that anyone can remember around here.”
So basically if the snowpack doesn’t become denser in a jiffy, a parade of trout and salmon could be relocated to cooler waters around the state instead of released into Valley creeks, lakes and rivers. The San Joaquin hatchery releases just shy of a million catchable size fish a year into waters that flow into the San Joaquin Valley.
Greg Kollenborn oversees four hatcheries in Central California.
“We’ll get through it,” Kollenborn says. “We have a certain number of pounds of fish allotted for every water annually and so that’s our game plan for the year and as conditions change we alter those to accommodate for the conditions of the year.”
But a warmer year isn’t always a bad thing according to these fish growers. Once again Greg Paape.
“The fish grow faster as the temperature gets warmer up to a certain point,” Paape says. “Once you reach that magic midway point then their growth slows down because the oxygen is lower in the water, but there’s that happy medium where the growth is good, the oxygen content is good, and they do real well.”
And that’s something that both fishermen and fish hatcheries will be monitoring closely as winter turns to spring in Central California.