Some baleen whales can become victims of bycatch, which is especially serious for North Atlantic right whales considering its small number. Right whales feed with a wide-open mouth, risking entanglement in any rope or net fixed in the water column. Rope wraps around their upper jaw, flippers and tail. Some are able to escape, but others remain entangled. If observers notice, they can be successfully disentangled, but others die over a period of months. Other whales, such as humpback whales, can also be entangled.