Fish biologist Jeff Finley cradles one of ten endangered pallid sturgeon captured in the habitat restoration site at Jameson Island unit of the Big Muddy National Fish and Wildlife Refuge. FWS Photo.

While scouring the Big Muddy for potential brood fish, a record number of the endangered pallid sturgeon were captured in one day at Jameson Island in an area smaller than a football field. 

“All hands on deck, we have a very short window of ideal conditions to collect gravid pallids!  Prepare all your boats and crews for some long hard days.” This was the tone set by Branch Chief of Missouri River Studies, Wyatt Doyle, in preparation for pallid sturgeon brood stock collection efforts.  The Mitigation crew heard the message loud and clear.  We responded by setting 8,250 hook trot lines in addition to our routine sampling protocol at Lisbon Chute.  Lisbon and Jameson Islands are both units of the Big Muddy National Fish and Wildlife Refuge in Missouri.  Lisbon has been touted as one of the best examples of a near natural side channel and is serving as a baseline for comparing constructed chutes.  Jameson Island, immediately down stream of Lisbon, has been one of the most contested Missouri River mitigation issues of the past year.  The Missouri Clean Water Commission balked at the Corps of Engineers for disposing of dredge material from the construction of this chute into the river.  Resolution of this issue is still being debated. Ironically, less than a quarter of a mile down stream of the disposal site we discovered the greatest concentration of pallid sturgeon ever collected by Columbia NFWCO.  This is a very unique area of the river.  It has large sand bar complexes formed on the inside of two of the tightest bends in the river and holds deposits of gravel; a substrate believed to attract spawning pallids.

Each spring Columbia NFWCO focuses efforts to collect federally endangered pallid sturgeon for brood stock.  Large, wild mature fish used for captive spawning are extremely rare.  Until evidence of natural reproduction occurs, the pallid’s existence throughout the Missouri and Mississippi rivers depends on artificial propagation to sustain their population.  Multiple state and federal fish hatcheries throughout the Missouri River basin are involved in rearing these fish.  A common problem facing endangered species is genetic stagnation whereby the genes of a few fish could swamp the genetic pool with related individuals.  Therefore the more wild fish we can collect the greater genetic diversity of the population being stocked.

So, what would it be like to shatter our office's existing record for daily pallid captures and find them concentrated in such a small area. Read on for Fisheries Technician Brett Witte’s account of that drizzly April day.

“The morning of April 18^th, 2008 began like many others for Zac Beussink, Jeff Finley, Joe McMullen and myself. Our crew set out from Columbia NFWCO for the boat ramp at Glasgow, MO. Our mission- pull 250 trot line hooks off eight lines, pull a chute’s worth of hoop nets from the river and process the catch. 

The first four trotlines of the day came into the boat w/ the usual catch of shovelnose sturgeon and catfish. No luck by that point in the search for the endangered pallid sturgeon. When the fifth line held only two channel catfish, hopes diminished that the three channel sandbar sets would hold any pallids. The sixth line was set along the channel side of the sandbar just like its predecessor. However, the crew’s day was about to get more exciting…and quite a bit longer.

As the first few hooks entered the boat Zac called out, “We’ve got a pallid!” as he heaved the ghost white fish into the boat.  Before the rest of the crew could respond Zac exclaimed, “Here’s another one!” It seemed the sandbar sets might do well after all. Within minutes, the 25 hook trotline was in the boat and five pallid sturgeon were swimming in a holding tub. It quickly became evident that four of the five fish were too immature to spawn and bore the marks of being born in a hatchery.  They had been implanted with a PIT tag or visibly marked with an elastomer tag. The fifth and largest fish was just millimeters short of being large enough for U.S. Geological Survey crews to implant with a transmitter for tracking spawning activity.  Given its size and having a PIT tag we suspected it was from the 1992 year class stocking.  Although none of these fish met brood stock criteria, it was still exhilarating to catch five endangered pallid sturgeon on one 25 hook trotline. 

Each pallid, even a hatchery-born fish, requires significant time to process. We record various measurements of the head, mouth and barbles and count rays in the dorsal and anal fins.  All pallid sturgeon are checked for PIT tags and elastomere tags to determine if they were hatchery born or previously captured in the wild.   Genetics samples are collected from all suspected wild fish (as opposed to hatchery-born) and voucher photos are taken of every pallid.  Just one pallid, especially a large brood stock candidate, can push back a crew’s lunch break or prolong getting off of the river, much less five.  Working them up was a significant task, but the crew was up to the challenge. A division of labor quickly fell into place and each fish was quickly returned to the river. 

Glad to have finished the most time-consuming short trotline of the year, the crew motored to the next line. This line was set on the bank side of the sandbar’s tail within 75 meters of the other line. Zac began to retrieve the last sandbar set and, would you believe it, the very first hook held a pallid!  It was nearly an instant replay of the previous line. By the time we pulled that trotline’s upstream anchor five more pallid sturgeon were sharing the honorary tub.  While one of these fish appeared to be wild, it was too small for brood stock. The rest were from one of multiple hatchery stockings. 

The fifty hooks of these two lines held all the pallids the crew would catch that day. The remaining lines and hoop nets in Lisbon chute held no pallids. However, ten pallids in one day and in such a small location is hardly an occasion to ignore.  Despite racing sundown back to the boat ramp on a Friday we all held our heads high having set a new record number to beat (for Columbia NFWCO at least).”

Brett Witte

Pallid sturgeon are extremely rare and finding a remnant of their wild population old enough to spawn is the proverbial “needle in a haystack”.  Finding a high concentration of pallids spanning two decades of stocking efforts in a small area of a mitigation site sends a positive signal regarding our collective efforts with the Corps to recover the species.  Over the years of our sampling, the Lisbon-Jamison units of the Big Muddy NFWR has produced the first evidence of wild spawning and the most pallid captures of any area on the Lower Missouri River.  Typically we catch pallids sporadically; rarely does one line or net hold more than one or two.  This begs the question, what is so special about this small area.  Do the sediments deposited by Corps construction mimic a natural erosion process from a period before the river was bound by rip-rap and dikes?  And are pallids drawn to such an occurrence?  What is so special about this sand bar and these two bends?  Or, perhaps, was it just a lucky day?