When one thinks of sharks one thinks of sleek, powerful predators that appear to cruise effortlessly but are capable of dazzling bursts of speed when they attack prey. This image of the shark is exemplified by the shortfin mako. We know makos are fast, but how fast? Many sources will tell you it is capable of speeds of 74kmph or greater. The truth is a little less dramatic. We now know that around 35kmph is probably the maximum speed of any fish through water, and that makos are probably capable of speeds around 30kmph, which still puts them right up there among the ranks of the elite fish speed merchants, and around four times faster than any human (for a more detailed, scientific account you read my marine-bio-images.com blog XXX). Makos are generally accepted as being the fastest of all sharks, and with that powerful, missile-like shape, they are definately built for speed. I have yet to get in the water with a mako – it is one of my goals for this year. In the meantime I have an unexpected surface encounter off Kaikoura to savour. Kaikoura, as many of you will know, is a small town on the north east coast of New Zealand’s South Island. It is famous as one of the best places in the World for whale watching, especially sperm whales. It also came the wider world’s attention in November 2016, when the region was struck by a 7.8 magnitude earthquake, cutting off road and rail links to the town, uplifting areas of seabed and causing a localised tsunami up to 7 metres in height. When we visited in February 2017, road connections were still disrupted and whale watching boats had difficulty operating due to sea level changes affecting there berthing alongside. The town, highly dependent on tourism, was suffering markedly. We were not there to look for whales though, we were looking for dolphin and albatross. Kaikoura may be most famous for whales, but it is also a fantastic place to see many species of albatross up close, and it was albatross and dolphin we were there to see.
Whilst the big whales grab most of the international headlines, the sheer drama of seeing several species of albatross up close – really close – soaring, wheeling and plunging down to feed, is pretty hard to beat. Nor was it just the albatrosses and giant petrels that noticed the food in the water. The scent of chum in the water attracted in predators from below also. A dark triangular fin broke the surface and began weaving through the wary seabirds. The shark was a juvenile mako, approximately 5-6ft (1.5-1.8m) long. Whilst clearly drawn towards us by the fish scraps in the water, it then became interested in the birds splashing around.
The great albatrosses eyed the shark with a mixture of wariness and belligerence; with a wingspan probably exceeding the length of the shark they may have seemed a little large to tackle. The smaller petrels were more anxious. It made a grab for one cape petrel that did not move out of its path fast enough, but the attack seemed have hearted and the petrel skittered away easily enough. There was probably enough fish remains floating in the water to keep the shark happy. Makos will occasionally take seabirds, but mostly feed on pelagic fish species such as mackerel, herring and anchovies. Larger individuals have been found to have young seals and even common dolphins in their stomachs, as well as billfish such as marlin. Common dolphins and marlin are both renowned for their speed, so whilst it is possible that these were injured individuals snapped up by the mako, it is also these fell prey to the makos lightening speed.
Graham, J. B., DeWar, H., Lai, N. C., Lowell, W. R., & Arce, S. M. (1990). Aspects of shark swimming performance determined using a large water tunnel. Journal of Experimental Biology, 151(1), 175-192.