The Field Site

The Strait of Gibraltar (photo credit: Philippe Verborgh)
We are based out of Tarifa, a small town located on the southernmost tip of Spain. This port offers excellent access to the Strait of Gibraltar, a narrow strait separating Spain and Morocco by 7.7 nautical miles (14 km) at its closest point. Here, the cold, nutrient rich Atlantic water meets the warmer Mediterranean waters, and the frequent upwelling provides lots of food for many marine  animals. 

Seven different whale and dolphin species are seen regularly in the area: Long-finned pilot whales as well as three species of dolphins (Common, Striped, and Bottlenose) are found here year-round; Fin whales, Sperm whales and fish-eating killer whales are found here seasonally, especially during the summer months.  Last week there was even a humpback whale.

Despite these animals, this is a very difficult place to conduct our research.  High mountains on both sides of the Strait and the junction of the Atlantic and Mediterranean mean that wind and waves build up really fast!  Although this wind makes Tarifa one of the world's premier kitesurfing destinations, it makes it extremely hard for us to tag whales.  The Strait is also an incredibly busy place: hundreds of cargo ships pass through on a daily basis, fast ferries connect the two continents, and fishermen and whale watchers constantly fill the area. Why would you ever base a research expedition here?

The answer to this question lies in the unique population of long-finned pilot whales.  Around 100 individual pilot whales reside in the area all throughout the year, and others  visit from the Mediterranean two or three months each summer. What's special about this site is that all of these animals are extremely well-known: researchers have used photographic techniques over the last 12 years to identify each and every animal and to understand how individuals associate with each other. Small pieces of skin and blubber have been collected for some animals, providing information about dietary niche, genetic diversity or even relationships between individuals. And all of these well-identified animals can be reliably found within an hour away from the port of Tarifa.  There's really nowhere else in the world where we these factors combine in this way.

Despite the tough working conditions, the amazing knowledge on the identity and association patterns of these animals therefore provides us with a wealth of background information that is unparalleled among pilot whales and only matched by a few other populations of whales around the world. This information helps us find and study the same well-known groups of pilot whales within and across field seasons, providing exciting opportunities for studying social dynamics and foraging ecology for a deep-diving, social toothed whale.

No comments:

Post a Comment