Dolphin Tales: Why do dolphins beach themselves
Two older adult male bottlenose dolphins beached themselves on separate beaches in Southwest Florida just this month. A necropsy of one of the dolphins revealed that it died from a brain blood clot, likely due to old age.
Another theory is that their deaths could be due to exposure to cyanobacteria. A neurotoxin called BMAA accumulates in the fish that dolphins eat. BMAA has been linked to neurodegenerative changes in the brains of stranded dolphins much like Alzheimer’s or Parkinson’s.
Most dolphins strand themselves because they are sick or injured. A single dolphin may seek shelter in shallow waters, wanting time to heal, but end up getting caught in a changing tide and be unintentionally stranded in its weak state.
Mass strandings of dolphins and whales is another story. Worldwide, about 2,000 marine mammals die of mass strandings every year. Navigational errors are believed to be the main cause. Echolocation is their primary navigational aid.
Whales and dolphins travel in groups called pods and are guided by a leader. If the leader loses its orientation, the accompanying animals will follow him/her in the wrong direction. Even if the leader is stuck in shallow waters, the rest of the group will stay with the leader.
Another explanation may be attributed to the earth’s magnetic field. It is thought that, as well as using echolocation, migratory whales and dolphins use the earth’s magnetic field similar to migratory birds. Crystals of magnetite have been detected in the brain and skull of some whales and dolphins. These crystals react to a weak magnetic field and could be used as an important navigational aid, especially in deep oceans.
Capt. Cathy Eagle has spent over 40 years boating in our local waters. As a professional charter captain she specializes in dolphin and nature tours. Visit CaptainCathy.com or call 239 994-2572.