A man is in critical condition after his paddleboard collided with a bridge abutment on the Bow River near Bowness Park Thursday afternoon, prompting a major rescue response by Calgary emergency crews.The Calgary Fire Department said crews were called at about 1:10 p.m. to reports of a paddleboarder striking the 85 St. N.W. bridge abutment.When firefighters arrived, they found the adult man face down in the water, still attached to his paddleboard by an ankle leash near the bridge support.Rescue crews relayed the victim's location to firefighters in an aquatic rescue boat while the Calgary Police Service HAWCS helicopter provided aerial support.Firefighters reached the victim from downstream and brought him to shore, where CPR was immediately started. Emergency Health Services crews continued resuscitation efforts before transporting the man to Foothills Medical Centre in critical condition.During the response, crews initially believed a second person may also have been involved in the incident.Firefighters later confirmed the second individual was the injured man's 11-year-old son, who had floated downstream after the collision and was safely pulled from the river by a bystander. EMS assessed the child and determined he was not injured.“The patient did have a personal flotation device on, but with the power of the river and the current itself, the person was pulled under the water and was attached to the paddleboard by an ankle leash,” said Calgary Fire Department Battalion Chief Bruce Barrs..The incident comes as paddleboarding continues to grow in popularity on Calgary's rivers. Fire officials said paddleboards have featured prominently in aquatic rescue calls this year, including the rescue of three paddleboarders on the Bow River during high water conditions in June.The Calgary Fire Department is again warning residents not to use ankle leashes while paddleboarding on moving water.Officials say ankle leashes can trap paddlers underwater if the board becomes caught on rocks, bridge supports or other obstacles, making it difficult or impossible to free themselves against the force of the current.The department said paddleboard leashes have been linked to at least two drowning deaths and several other serious incidents in recent years.Fire officials recommend paddleboarders avoid using ankle leashes on rivers and instead label their boards with contact information if they are concerned about losing them. They also warned against using anchors in moving water because they present similar entanglement hazards.The city is encouraging residents to review river safety information and monitor current river conditions before heading onto Calgary waterways.