Blackrock Fish Hatchery broodstock, those big trout used for spawning to propagate future generations, are being released in the Lower Owens River.
This week marked the second large-scale release of the hatchery’s broodstock in as many months, and the Department of Fish and Wildlife said there is going to be at least one more release in the coming month.
DFW Environmental Biologist James Erdman said he and other DFW biologists wanted to let all anglers know that the big broodstock fish from the ponds at the Black Rock Hatchery are now up for grabs.
The fish have been planted in the Owens River below Tinnemaha Reservoir. One release was done this week and another was done April 22. The fish are mostly browns and rainbows between 3 and 5 lbs. each. This week, Erdman said the DFW released 222 fish in a load that weighed 1,000 lbs. In April, the hatchery released 317 fish with a total weight of 950 lbs.
The fish have an average weight of 3-4.5 lbs.
“These super-catchable and trophy fish are available to be caught by any one with a valid fishing license,” Erdman said.
The DFW is releasing the broodstock for two reasons. The first, Erdman said, is because the invasive New Zealand mudsnail, which is common in the Owens River, has been identified near the broodstock ponds. Erdman explained that most of the hatcheries functions are well- and spring-fed from water sources that are not infested with the invasive species.
However, the broodstock ponds are located adjacent to the river. “This is a preemptive strike,” he said. “We’re clearing the fish out to ensure that the mudsnails from the river don’t get into the hatchery operation.”
The second reason, he added, is because local hatcheries are switching from their traditional rearing of rainbows and browns to the sterile triploid trout which, because they don’t use any energy on reproductive functions, grow faster.
The benefit of releasing the trout is also two-fold.
By stocking the Lower Owens with the broodstock, Erdman said, anglers fishing waters south of Tinnemaha Reservoir will have a better chance of landing a lunker. He said he has already heard reports of residents catching some of the big fish on the Lower Owens.
He also said the broodstock, as breeders, will help get the fishery on the river established as the river reclaims its original course, which was dry from the early 1900s until 2006, due to the Los Angeles Department of Water and Power diverting water into the Los Angeles Aqueduct.
He did point out that the Lower Owens is one of the warmer bodies of water in the Sierra, and trout generally seek out colder waters to spawn, but that won’t stop the broodstock from reproducing.
Aside from the benefit of helping to establish a healthy trout population in the LORP, Erdman said the DFW selected the Lower Owens for broodstock stocking because of its proximity to the hatchery.
“Because we electrically shocked them, the fish get very stressed out, so we try to get them as quickly as we can to the water, and the Lower Owens is literally right there,” he said.
Blackrock will continue to produce trout after the remaining broodstock is released, but it will be dealing in triploid rainbows rather than the mix of browns and rainbows it currently produces.
The trout that have been released in the LORP are a mix of about 70 percent browns and 30 percent rainbows.
“We’re not quiet done releasing the broodstock, we have at least one more event planned,” Erdman said. “And we just thought it was good to let all the anglers know these big fish are out there.”