This story has been updated since the December 22, 2022 announcement. All updates regarding the stingray touchtank in the Delta will be added here.
Update January 20, 2023
The National Mississippi River Museum & Aquarium has completed its investigation and confirmed preliminary findings from the December incident following a malfunction in its Delta exhibit’s alarm system. The River Museum has since replaced the alarm system and is currently in the process of acclimating additional stingrays in the Delta exhibit located in its National River Center.
Upon arrival in the morning on December 22, staff in the Delta noticed animals in distress and immediately began steps to determine the cause. The exhibit appeared to have experienced a supersaturation event after water levels in the tank dropped due to excess evaporation from dry, cold winter temperatures. The exhibit’s monitoring system showed a spike in oxygen levels in the late evening hours but did not send an alarm notification to staff as expected.
Eight stingrays were lost. One Cownose Ray was in stable condition at the time of the incident and has since recovered.
The necropsy, or animal autopsy results, confirmed the cause of death of the stingrays in the Delta was gas bubble disease, comparable to decompression sickness in humans. This supports the preliminary internal investigation conducted by the Living Collections department. Alarm systems, which failed to alert staff to the issue, have since been replaced.
On January 18, staff welcomed additional Cownose Rays, raised in human care, from a regional Association of Zoos and Aquariums (AZA) accredited facility. The animals were closely monitored by the River Museum’s aquarists throughout transport and upon arrival. The Cownose Ray and two Yellow Stingrays on view in the Delta have been moved to a separate holding system to allow the incoming stingrays additional space for quarantine and acclimation, as is standard procedure for all new animals at the facility.
The Delta remained closed until Friday while the animals adjusted to the new environment and is now open for viewing capabilities.
“Animal health and welfare is one of our top priorities at our facility,” said Abby Urban, Curator of Living Collections. “These animals came from a touch tank at the previous facility, and we expect them to acclimate to our campus well. The animals’ acclimation is being evaluated by the Living Collections team and veterinarian, and their progress will determine when stingray touch experiences can be offered again.”
The Living Collections team and River Museum staff extends their gratitude for the positive support from the community, visitors, and AZA institutions throughout the past month. Visitors are encouraged to check rivermuseum.com for additional updates as they become available.
Update December 30, 2022
On Thursday, Dec. 29, the Living Collections staff moved additional stingrays from holding to the Delta in the National River Center after evaluating the exhibit’s water quality and the remaining Cownose Ray’s health. Touch tank capabilities are still on hold until further notice to allow the animals to adjust to their environment. The Living Collections team is also looking to add saltwater fish to the system in the coming weeks. A few Jacknife fish have been moved to the exhibit with the additional stingrays.
Continue to check signage at the box offices and online for updates as they become available.
Original Post: December 22, 2022
The Living Collections team at the National Mississippi River Museum & Aquarium is devastated to announce the Delta in the National River Center is closed, and stingray feedings and touch tank capabilities are on hold until further notice as staff and the veterinary care team investigates the cause of death of eight stingrays on Thursday.
Upon arrival on Thursday morning, staff noticed animals in distress and immediately began steps to determine a cause. The exhibit appeared to have experienced a supersaturation event, following a malfunction in the life support system, causing gas embolisms, or gas bubble disease, in the animals. The exhibit’s monitoring system showed a spike in oxygen levels late Wednesday night, but did not send an alarm notification to staff as expected. The cause of the malfunction and lack of alarm notification is still under investigation.
Five Cownose Rays, two Yellow Stingrays, and one Atlantic Stingray were lost. One Cownose Ray remains in stable condition.
While preliminary reports suggest a supersaturation event, the cause of death will not be confirmed until necropsy results, water quality testing and toxicology reports are complete. Results could take up to several weeks.
“Our staff is heartbroken over this loss and are taking steps to ensure this does not happen in the future,” said Andy Allison, Vice President of Living Collections and Education. “We are reevaluating our life support and monitoring systems for all exhibits including new systems being constructed within the Rivers to the Sea exhibit space. This is a difficult time for everyone at the River Museum and we ask for visitors’ patience and understanding as we provide care for our remaining stingray and move forward.”
The life support system maintains water quality and conditions in the exhibit, while the monitoring system ensures alarms and notifications are sent should exhibit conditions shift outside set parameters. The system is checked at least twice daily by trained aquarists on staff and the River Museum’s maintenance team. Initial indications point to this being a chance incident and steps are being taken to review the system.
The Delta is expected to reopen Friday, December 23; however, touching and stingray feedings will be discontinued until further notice. The River Museum remains open during regular hours and visitors are asked to check the website for any updates related to the Delta exhibit.