Pallid Sturgeon Recovery, by Dina Coutu

September 6th 1990 was a big day for the Pallid Sturgeon, it was the day that it was listed as endangered and the race against time started for the species. According to the Fish and Wildlife Services website the species had started seeing a steady decline since the mid to late 1960s. We need to figure out how and why to stop this decline before they become extinct. This paper examines the general biology and habitats of the species, what is causing/has caused the steady decline to the species’ populations, what recovery plans have been made, what the results were for these plans, and what does the future look like for this species. Other Scaphirhynchus sturgeons are described in another post.
 

Technician shows the Pallid Sturgeon with distinctive pale coloration and flattened snout. photo by US Fish and Wildlife Service.

             If you find yourself in the Mississippi River and happen to see a Pallid Sturgeon you might think you have taken a step back in time. Scaphirhynchus albus has a flattened snout with feathery barbels,  they lack a spiracle, have a long slender tail with boney plates, and ganoid scales. Pallid Sturgeons can get on the bigger side of the sturgeon family, reaching lengths of 6 feet, and up to 80 lbs. These are not to be confused with their close cousins the Shovelnose sturgeon. These two species are often confused for each other thus leading to the 2010 listing as an endangered species based on similarities of appearance. (U.S. Fish & Wildlife) The smaller differences make these two species difficult to distinguish, but the best way is to pay close attention to color and barbel length. According to the Fish and Wildlife, the current range of this species is scarce from the upper Missouri River down past the Gavins point dam. They are also found in the Mississippi and Atchafalaya Rivers. They are bottom dwelling fish that feed on small fish and invertebrates. These fish can live close to 50 years of age but have a long time to reach sexual maturity, 7-9 years of age for males and 7-15 years of age for females (U.S. Fish Wildlife 2018).  The sturgeon habitats have been greatly impacted and fragmented. This is  believed to be one of the biggest conservation issues for this species.

 

Contemporary range (red) of Pallid Sturgeon in Mississippi River Basin (Pallid Sturgeon Recovery Team 2014)

  Since the 1960s biologist have come together to try and study this endangered creature that looks like it stepped out of a time warp. As of 2014 eight species along with one subspecies are recognized as valid under the Acipenseridae family. Of these nine valid species seven of them are on the Federal list of endangered and threatened wildlife, with the Pallid Sturgeon being listed as endangered (Revised Recovery Plan). Before their habitat became fragmented by dams and other human structs Pallid sturgeons would migrate hundreds of miles upstream to deposit their eggs to be fertilized. Once the eggs hatched the larvae would drift back downstream over a period of several weeks.   In 2007 two female sturgeons were seen for the fist time in close to 50 years spawning in the wild downstream form the Gavins Point Dam. (USGS pg 1) The USGS and NGPC have been working for many years to figure out how to save this prehistoric species. In the spring of 2007 they teamed together to study habitat availability and how it affects the Sturgeons reproduction success. They attached radio transmitters and tagged 195 individual sturgeons (a combination of Pallid and Shovelnose)and tracked their movements through the water channels. (USGS pg 1) From there they were able to find what areas the wild sturgeons preferred for spawning. This study provided biologist a better understanding of the optimal conditions the Sturgeons prefer to attempt to spawn and breed. 

            In the past 20 year we have seen an increase in interest for the sturgeons and wide range sampling efforts have been made, but we still do not have a good grasp on the actual status of this species. The estimate number of individuals is 2,500-100,000.   What has been seen is a continuous decline in the Missouri River basins wild populations and the Mississippi River populations is still in question.  It is estimated that 36% of the sturgeon natural habitats have been eliminated due to damn constructions, another 40% has been channelized, while the rest has been altered as a result from the 76% man made destructions. 

            Other conservation issues the Pallid Sturgeon faces are, hybridization, disease, the harvest of their roe for caviar, they are a desirable trophy sport fish due to their odd features and large size, and they are also considered to be tasty. Even though the Pallid Sturgeon is considered endangered people still misidentify them (either due to lack of proper knowledge or due to hybridization) as their close relative the Shovelnose and harvest them for commercial, recreational, and educational purposes. This has lead to the overlap of protection where hybridization and habitats overlap for the Pallid and Shovelnose (U.S. Fish Wildlife 2018). Missouri River sturgeon iridovirus is a disease that was once though to be only seen in hatchery-reared sturgeons, in 2003 it was recorded in wild populations (Revised Recovery plan. pg 33). This diseases has shown high mortality once it spreads in a hatchery environment. But with all that this species faces will it pull through and prove to us it hasn't survived since the dinosaurs to be eliminated by humans? 

Multiple recovery action plans have been discussed and implemented to attempt to bring this species back from the verge of extinction. The latest revised plan was written and reviewed in January 2014. The main strategy points this plan talks about is: limiting hybridization to keep the genetic diversity of the populations, create and maintain management units of each population demographics, improve the population numbers, reduce threats as most as possible, and use hatcheries to try and supplement the populations that are declining (Revised Recovery plan. pg 47).

Collecting Pallid Sturgeon and educating children.  Photo by US Army Corps of Engineers, Kansas City.

                        This plan focuses on four different locations to attempt to implement the recovery actions. The great Plains Management Unit (GPMU) contains a natural barrier that inhibits the sturgeons from migrating. The Central Lowlands Management Unit (CLMU)  includes important tributaries. The Interior Highlands Management Unit (IHMU) , and the Costal Plain Management Unit (CPMU) are also targeted in this action plan. (Revised Recovery plan. pg 48) In each of these four locations conservation and reservation efforts are taking place, with the main goal of creating a self sustaining wild population. The estimated number for each population to reach to be able to become self sustaining is 5,000 adults. (Revised Recovery plan. Pg 54) Not only do we have to implement new strategies for conservation and restoration, we also need to do more research. In each of the four management units new studies have/will done as well. Historically the practice of modifying dikes to create habitats  to restore riverine functions for different fish species has been used but recently we are seeing this may not be the best option. (Revised Recovery plan. pg 73)

            Currently there is a stocking and hatchery program in place for the Pallid Sturgeon. Hatcheries are breeding sturgeons and rearing them to juvenile ages, then releasing them back into their habitats. These reared fishes are then monitored and studied to learn their success rate and what can be done to help the numbers increase.  Education is another important factor that needs to be implemented for this species to recover. Methods need to be developed for proper species assignment. Not only to a biologist but to the everyday fisherman who might come across the sturgeons. 

Taking eggs for breeding program for Pallid Sturgeon.  Photo by US Fish and Wildlife Service.

Even with a few decades worth of studies and research biologists are struggling to understand and prevent further decline of the species. Along with further restoration and conservation methods we need to educate. We need to educate not only ourselves as biologists, but we need to educate the public. People do not care about animals they do not know about, about animals they have never seen, about animals that do not affect them. If we can make a Pallid Sturgeon as popular are a small mouth bass, people will get interested, people will care, people will learn, and people will help. For a little less than 30 years we have been asking ourselves how do we stop this decline from happening, and we still do not know the answer.

References

NatureServe Explorer. November 2016. Scaphirhynchus albus.

http://explorer.natureserve.org/servlet/NatureServe?searchName=Scaphirhynchus+albus

USGS. July 2007. Sturgeon Research Update: Confirmed Pallid Sturgeon Spawning in the Missouri River in 2007. USGS Fact Sheet 2007-3053.

https://pubs.usgs.gov/fs/2007/3053/pdf/FS2007-3053.pdf

Pallid Sturgeon Recovery Team. Dalbey, S., Dean, J., DeLonay, A., Gardner, B., Herzog, D., Et al. January 2014. U.S. Fish $ Wildlife Service Revised Recovery Plan for the Pallid Sturgeon.

U.S. Fish & Wildlife Service. March 12 2018. Endangered Species Fact Sheet Pallid Sturgeon.

https://www.fws.gov/midwest/endangered/fishes/pallidsturgeon/palld_fc.html