Rescue workers are planning how to extract a beluga whale from the River Seine.
The Arctic mammal has found itself trapped between a set of locks in a stretch of the watercourse between Paris and Rouen.
Efforts are continuing to try and get the whale to eat, but they have so far failed.
The marine conservationist group Sea Shepherd France said on Monday that “feeding attempts are continuing in parallel to finding a solution to get it out of the lock in the best conditions”.
Over the weekend, the beluga was given a “vitamin cocktail” in an attempt to keep its nutrition up.
Lamya Essemlali, president Sea Shepherd France, told a news conference this weekend: “It is really extremely thin. Its bones are protruding. I don’t know if it’s already too late”.
Attempts to feed the animal – with both dead herrings and live trouts – have proved fruitless.
The beluga was first spotted in the river, thousands of miles from its homeland, last week.
It is now dozens of miles away from the sea and its normal salty environment.
Experts have warned the whale should not stay too long in the warm, stagnant water between the two locks where it currently resides.
“The beluga still doesn’t eat but continues to show curiosity,” Sea Shepherd France tweeted. Overnight the whale “rubbed itself on the lock’s wall and got rid of patches that had appeared on its back. Antibiotics may also have helped.”