A humpback whale that had been stranded for days off Germany’s Baltic coast has become stuck again, a Greenpeace spokeswoman said on Saturday. The whale first ran aground early Monday on a sandbank off the Timmendorfer Strand resort near the northern city of Lübeck, drawing widespread media attention. What else do we know about the stranded whale? Marine conservation group Sea Shepherd says the mammal is likely a young male on migration and believes it could be the same whale repeatedly sighted in the area earlier this month. Repeated attempts to free the 12 to 15-meter animal failed until Thursday, when rescuers used a floating excavator to dig a channel around it, allowing the whale to swim off later that night . Environmental groups and marine specialists had warned the whale might run into trouble again after it was seen moving back toward shallow waters.…