Firefighters oversaw RSPCA officers rescue a seal who is on a pontoon near Kew Bridge in Brentford.
Station Manager Andy Walton, who is at the scene said: "We were called by the RSPCA and fire crews were there to ensure the safety of RSPCA officers. The RSPCA officers safely caught the seal in a noose and placed it on a rescue mat.
"With the help of firefighters the seal was carried via a pedestrian bridge into an animal ambulance."
The seal was taken to the animal hospital to have his eye treated but didn't survive.
An RSPCA spokesman said: “Very sadly, the seal was so unwell that he died before he arrived at the specialist wildlife centre we hoped would care for him. It is believed that the cause of death was underlying disease.”
The Brigade was called at 0952 and the incident was over at 1135. Two fire engines and two fire rescue units were at the scene.