The USGS Comprehensive Sturgeon Research Project is a multi-year, interdisciplinary research study to determine factors leading to spawning and survival of the endangered pallid sturgeon and the closely related shovelnose sturgeon.
Experiments Begin in New Eco-flume at CERC
May 26, 2023
This week marked a milestone in the development of laboratory capabilities to study the effects of flow and hydraulic variation on early-life-stage sturgeon at the USGS. For the past three years the USGS has worked with the Saint Anthony Fall Hydraulics Laboratory (SAFL), University of Minnesota on the design and construction of an advanced eco-flume (see previous blog, Eco-flume Arrives at CERC). The CERC Eco-flume was completed in early Spring 2023 and the first experiments began this week.
On Wednesday, May 24 CERC scientists added 5,000 1 day-post-hatch (dph) free embryos into the flume (see previous blog post, Laboratory Studies Begin with Spawning). The downstream dispersal behavior of free embryos was studied with a range of water velocities provided by novel, low-turbulence paddles designed by SAFL engineers. The paddles are designed specifically to move water so free embryos and larvae can swim normally while preventing injury to these fragile early life stages. Mortality during the initial experiment was extremely low (0.2%), indicating that the flume is operating as designed. CERC scientists are using high-speed digital cameras to monitor downstream velocity of dispersing free embryos, document their swimming behaviors, and record their distribution with depth. Analysis of video data will use machine-learning techniques developed in collaboration with the University of Missouri, Department of Civil and Environmental Engineering.
Experiments with pallid sturgeon free embryos and larvae will continue through June 2023 with 5-, 8-, 11-, and 14-dph larvae. Studies will evaluate their swimming capability and innate behaviors and provide understanding on the effects of development on early life-stage dispersal. Later in 2023, CERC scientists will experiment with older larval and juvenile life stages, and with bedforms placed on the bottom of the flume to evaluate how natural roughness elements may slow dispersal.
The motivating research questions driving the development of the Eco-flume at CERC have been linked with transport and fate of free embryos and larvae of the endangered pallid sturgeon. How far free embryos and larvae drift before they can hold themselves in the current and start feeding is a key variable in management decisions for the Missouri River supporting recovery of the species. In addition to studies with sturgeon, the flume will provide experimental capacity to study numerous species in flowing water, including other imperiled fluvial fish species, invasive carps, and native mussels.
May 18, 2023
The Comprehensive Sturgeon Research Project performs many studies each year with early life stage sturgeons. These include studies of genetics, development, biomechanics, behavior, and the development of new marking and tagging strategies. This requires CERC scientists and their partners at the USFWS Gavin’s Point National Fish Hatchery (GPNFH) to consistently spawn adult sturgeon in captivity to produce tens of thousands of sturgeon eggs, newly hatched free embryos, and larvae for planned research studies each year.
Both CERC and GPNFH maintain captive broodstock that are used to produce young sturgeon for research. On May 18, 2023 scientists at CERC artificially spawned adult pallid sturgeon broodstock to produce the young sturgeon needed to begin dispersal experiments in the new Eco-flume (see previous blog, Eco-flume Arrives at CERC). Three male and five female pallid sturgeon from the CERC captive broodstock were injected with hormones in the days preceding spawning. The injections were precisely timed so that the female sturgeon ovulate or release eggs early in the morning on the day of spawning. Eggs were “stripped” by hand from the females at intervals of approximately one hour by applying gentle pressure to their abdomens and pushing downward toward their tail. The eggs were collected in shallow bowls and mixed with milt (sperm) collected from the males to fertilize the eggs. Fertilization was done in the dark. Fertilized eggs (embryos) were maintained in the dark for several hours before being transferred into hatching jars where they incubate for about 5 days before hatching.
Spawning on May 18 was unusually successful. The five females each produced between 45,000 to 63,000 eggs, for a total of about 260,000 eggs. The total weight of eggs produced by adult female sturgeon ranged from 11 to 17 percent of their bodyweight. Fertilization rates determined within hours of spawning exceeded 95 percent. Scientists will monitor the development and hatch of the fertilized embryos for the next five days while preparing to begin experiments in the Eco-flume with 1-, 5-, 8-, 11-, and 14-day old pallid sturgeon.
CERC Scientists Facilitate Pallid Sturgeon Data Integration
April 26, 2023
Informed management decisions to support recovery of the endangered pallid sturgeon in the Upper Missouri River Basin have been challenged by data integration. Multiple State, Federal, and University partners hold key information on capture locations, tagging, genetics, migrations, habitat use, and spawning. Each partner employs a range of different data collection, management, and reporting strategies. A team of scientists and data specialists from the USGS Comprehensive Sturgeon Research Project at CERC was funded by the Western Area Power Administration to assist in developing standardized data collection and submission processes to ensure that all partners are collecting a minimal set of compatible data to contribute to common research and monitoring needs.
The USGS Sturgeon Data Team met with State and Federal partners from the Upper Missouri and Lower Yellowstone Rivers in Williston, North Dakota, April 25–26, 2023, to determine data infrastructure and processes to facilitate rapid reporting of critical data for Pallid Sturgeon monitoring. Kimberly Chojnacki, Chad Vishy, and Parker Golliglee discussed potential areas for data enrichment, appropriate relational database architecture, and data sharing. Based on input from partners within the basin, the Sturgeon Data Team analyzed the existing data streams and outlined critical data to develop a unified relational database architecture and to facilitate reporting of essential data to all partners The team used these data to demonstrate data-driven tools designed to assist in decision making, both in the office and in the field.
Sediment Burial Reduces Sturgeon Embryo Survival and Hatch
January 15, 2023
Researchers from the U.S. Geological Survey, Columbia Environmental Research Center (CERC) recently published the scientific article, “Effects of Substrate and Sediment Burial on Survival of Developing Pallid Sturgeon (Scaphirhynchus albus) and Shovelnose Sturgeon (S. platorynchus) Embryos” in the journal, Environmental Biology of Fishes. The endangered pallid sturgeon and common shovelnose sturgeon both spawn in flowing water, depositing their adhesive eggs on the river bottom, near or over coarse substrate (typically gravel and cobbles). Surveys have shown that the habitats where sturgeon spawn in the Missouri and Yellowstone Rivers are dynamic and that coarse substrates in these areas may be episodically buried by finer, mobile sediments, such as sand and silt (see previous blog, USGS Scientists Assess Pallid Sturgeon Spawning Habitat). Fine sediment can dislodge adhesive eggs of riverine species or bury them and deprive them of oxygen during incubation.
In this controlled laboratory study, researchers evaluated the survival of both pallid sturgeon and shovelnose sturgeon embryos (fertilized eggs) in various substrate conditions designed to simulate possible fates in a sand-bedded river. Newly fertilized embryos were allowed to develop on substrates of clean glass (control), gravel, medium-coarse sand, or fine sand-silt in aquaria for 10 days (5 days beyond expected onset of hatching). Embryos in aquaria with medium-coarse sand and fine sand-silt were tested with three different burial scenarios; unburied, partially buried, and fully buried. Embryos in partial burial treatments were uniformly covered by sediment without being fully buried. Embryos in the full burial treatments were completely covered to a depth of approximately 1–2 mm. For both species, hatch of normally developed free embryos was significantly reduced by burial in fine sediments. Results from this study indicate that these sturgeon species are intolerant of burial by even small amounts of mobile, fine sediment. Suitability of spawning and incubation habitats for endangered pallid sturgeon and shovelnose sturgeon may be dependent on river conditions that result in persistent patches of clean, coarse substrate.