John Paul Tiernan
One of the more interesting things about exploring marine life is that it often leads to more questions than answers as we constantly encounter elements of the marine world which we will never fully understand. Last week, a phonecall about a stranding of a whale and its calf on a beach just south of here prompted an investigation and sure enough, unearthed a question or two.
The animal in question, now residing most inelegantly between two rocks in the corner of a lonely beach, clearly having given birth to a newborn calf which was some 50 metres away, was similar in size to a dolphin, but its unusually shaped head, lacking a nose or ‘beak’ meant my marine mammal identification skills were put to the test. The blunt square forehead helped me to narrow it down to either a Risso’s dolphin or a pilot whale (which is actually a species of dolphin). Pilot whales very often strand, often in great numbers, however the pilot whale’s fin is far more curved than this animal’s was. The presence of a great number of scratches and scrape marks along the upper part of the body confirmed this to be a Risso’s. This was mystery one solved. Risso’s dolphins obtain these marks from the teeth of other Risso’s and from bites from squid, one of their main prey items. Why exactly Risso’s are biting each other is, unsurprisingly, not very clear to us yet.
Mystery two arose when we went to record the stranding on the Irish Whale and Dolphin Group’s (IWDG) website. It appeared that the stranding had already been recorded there by a friend, however his recording was two weeks old and only concerned one animal; no calf had been present. Mystery two was thus how the calf managed to end up so close to its mother after two weeks and when exactly did the whale give birth? Closer examination of a photo from that first recording showed the tail of the calf had started to protrude from the mother so indeed she had started to give birth when she stranded. The last question was what had helped complete the calf’s removal from the mother? Was the calf removed posthumously and by whom? Or what? A beach-going fox was one speculation; the lamb-size calf would be a comfortable carcass for it to work on.
The most fundamental question of course is why do dolphins and whales strand (often alive), on our beaches in the first place? There are various theories, including damage to the animals’ echo-location caused by excessive underwater noise from marine activity, but the only thing we can be certain about is that once again - we’re really not sure.
