F&G biologists studying how environmental conditions and C.J. Strike sturgeon fishery interact

After a concerning number of dead sturgeon washed up in a stretch of C.J. Strike Reservoir in late summer 2022 amid abnormally low oxygen levels and high water temperatures, Fish and Game issued a temporary conservation closure for sturgeon fishing. By themselves, the environmental conditions in 2022 approached – and even surpassed – known lethal limits for sturgeon. Knowing that angling might cause additional stress that could push the sturgeon over the edge, the department closed the fishery – an extremely rare action. 

“This population of sturgeon is an extremely important one for a number of reasons,” said Statewide Fisheries Manager Joe Kozfkay. “It’s one of the largest populations in the state, and it is one of just two that are self-sustaining. It is also being used as the egg source for our sturgeon hatchery program, which is critical to conserving sturgeon in Idaho.”

With the difficult decision to close the fishery, Fish and Game committed to studying the interactions between angling effort and environmental conditions in the reservoir, and whether those interactions contribute to excessive sturgeon mortality.

“We know that angling alone isn’t the problem: There are sturgeon fisheries elsewhere in Idaho where fish are caught and released multiple times – sometimes in the same day – without issue,” said Southwest Region Supervisor Josh Royse. “However, we are interested in learning whether angling might contribute to sturgeon dying in C.J. Strike, specifically when these environmental conditions develop in the late summer.”

Shortly after the temporary conservation closure went into place in 2022, fisheries biologists at Idaho Fish and Game began developing a suite of strategies to characterize any interactions between the catch-and-release sport fishery at C.J. Strike and seasonal environmental conditions within the reservoir. Fish and Game began to put those strategies on the ground in the spring of 2023. 

At the forefront of the ongoing sturgeon work at C.J. Strike is Regional Fisheries Biologist Phil Branigan. In recent months, Branigan and his team have been interviewing C.J. Strike sturgeon anglers to determine how much fishing effort occurs and how many fish are being caught during all portions of the year, including during environmentally stressful periods. In addition, biologists have also been scouring the reservoir for sturgeon carcasses and completing cause of death investigations for each one they find, as well as conducting hook-and-line surveys and implanting sturgeon they catch with acoustic telemetry tags (which allow biologists to track movements of fish within the reservoir). 

“The effort we are putting into this sturgeon study is monumental, and some facets of this study will likely span a decade,” Branigan said. “But seeing one of these fish up close and getting your hands on a nearly 10-foot creature that could very well be 100 years old reminds you why that sort of effort is warranted.” 

Anglers will play a critical role in helping fishery managers build a robust picture of how the fishery and environmental conditions interact. 

Here’s how anglers can help: 

Creel data is critical

One important part of the ongoing work at C.J. Strike are creel surveys of sturgeon anglers, which is a record of single day’s fishing effort that provides details on what an angler caught and how much time was spent fishing. 

Since April, Fish and Game staff have been interacting with sturgeon anglers on C.J. Strike, looking to glean this information at one of the reservoir’s boat ramps, or on the water while anglers are fishing. Depending upon where this interaction occurs, anglers may have some follow-up to do to provide biologists with the best information possible.

“We are looking for that complete snapshot of a single day’s worth of fishing effort, and we are able to capture that full picture at the boat ramp when people are leaving the reservoir,” Branigan said. “But most of our contacts for this creel survey are occurring while folks are still actively fishing for sturgeon, so we need those anglers to help complete that picture when they’re off the water.”

Fish and Game staff are providing all sturgeon anglers who were contacted on the water with a postcard with a unique pin code that includes a link to a survey for them to fill out at the end of their fishing trip. 

“Having that last piece of information from the postcard survey really gives us the best possible creel data to work with, and anglers can really help us by completing the online survey and submitting it to us,” Branigan added.

Report dead or dying sturgeon

Biologists can collect useful information from dead fish to help determine cause of death — which is something Branigan and his team are interested in for this study. However, the window for being able to determine cause of death after a fish has died lasts only a few days during the warm summer months. 

Currently, reservoir conditions (in terms of dissolved oxygen and water temperatures) are trending toward those observed prior to the conservation closure in 2022, when biologists documented more than 20 dead sturgeon from C.J. Strike.

“We have already collected a few dead sturgeon during this summer’s study period, and it’s quite possible that we could see additional mortalities in the coming weeks given current conditions,” Branigan said. “In order for us to be effective in investigating what contributed to the death of these fish, we need to get our hands on them as soon as possible. And to do that, we need anglers’ help in reporting dead sturgeon when they see them.” 

Anglers can help manage and conserve this important native fish by reporting observations of dead or dying white sturgeon using the online reporting tool (idfg.idaho.gov/report-sturgeon) or by calling their nearest regional office.