In places where there is apparent residency of certain species, we are interested in their behaviour.

How far do they forage? Do groups remain cohesive over time? Do they display daily routines? Do they carry out migrations at certain times of the year?

As well as following species such as the scalloped hammerhead, Galapagos shark and whale shark, which occur over the entire region, each area is also studying species which appear to be more resident.

For instance in Galapagos, a new study of a group of white-tip reef sharks has begun in Santa Cruz island, in the centre of the archipelago.

And in Malpelo, efforts have focused on an elusive shark: the smalltooth sandtiger, known affectionately as “the monster”. This species prefers depths greater than 50 metres, so getting close enough to observe and tag them is a great challenge.

Species under study

Scalloped hammerhead – Sphyrna lewini Location: Galapagos, Ecuador.

So far we have tracked 7 hammerheads for up to 80 hrs in Wolf Island, Galapagos. The sharks were tagged and studied one by one using ultrasonic transmitters. These transmit data pings every 3 seconds which are picked up by a hydrophone mounted on the side of a small boat which follows the tagged shark. We not only recorded the sharks’ position over time, but also their depth, water temperature and salinity and batymetry (seafloor relief), to get an idea of behaviour and habitat preferences.

Our results show that Hammerheads show two main types of movement patterns: inshore patrolling and pelagic excursions. During inshore patrolling the sharks remain day and night near the island, particularly moving up and down the southeast side of Wolf Island, also known as a “hotspot” for sharks (see Hearn et al. 2010). In pelagic excursions, the hammerheads ventured to the east of Wolf around dusk and returned to the island before dawn.

It is interesting to see that upon departing the island or coming back, the hammerhead made a deep yo-yo dive to 250-300 meters. (Prof. Klimley has described such diving as a way hammerheads navigate from their central abode to their foraging areas and back using geomagnetic fields present in the lava ridges extending outwards from seamounts or volcanic islands like Wolf.)

The extent and intensity of use of different areas around and close to an island reveal the home range of a species. In Wolf Island, hammerheads patrolling day and night show a home range restricted to the southeastern corner or hotspot of the island. On the other hand, those sharks performing pelagic excursions have core areas of higher intensity of use both inshore at the hotspot and offshore at potential foraging grounds.

Regarding depth, we found that Hammerheads remain in shallow water (10-40 m) when near Wolf, and go a bit deeper during most of the foraging excursion (~50 m). However, may dive quite deep as far down as 900 m when performing yo-yo diving at night further away from Wolf Island.

Hammerheads seem to prefer warmer, surface waters throughout the day and night. They generally remain at or above the thermocline (the depth where the sea temperature changes abruptly), only occasionally venturing into cooler waters below.

Galapagos shark – Carcharhinus galapagensis Location: Galapagos, Ecuador

We track individuals for 48 hour periods to understand their foraging habits.

Whitetip reef shark – Triaenodon obesus Location: Galapagos, Ecuador

We are looking at the social structure and daily behaviour of a small group of this species.

Sandtiger shark – Odontaspis ferox Location: Malpelo Island, Colombia

Interest in this species comes from the relative lack of historic information compared with other species, as seen in its IUCN entry (see ‘History’, under ‘Assessment Information’).

The Colombian island of Malpelo represents a unique opportunity to study Sandtiger Sharks, as it is one of the only places where they can be seen in the wild. They also display a significant degree of site fidelity, making the island an ideal place for long-term research.

A total of five individuals have been satellite-tagged so far, all at the “Bajo del Monstruo” at a depth of 60-70 feet. Additionally, ultrasound tags were used in two of those five individuals.

Preliminary results tell us that their presence in the island follows seasonal patterns. During the cold water season the tend to remain around the island all day and night, while in the warm water season they tend to leave the island during the day, in some cases returning during the night. Some however, leave the islands for weeks or months.

The tags registered depths of 1.000m and up to (and presumably beyond) 2.000m, the tags’ measuring limits.

Manta ray – Manta birrostris Location: Isla de la Plata, Ecuador

We have developed a photo ID library and placed receivers at Isla de la Plata, where we have tagged 5 mantas. We have also begun tracking individuals.

Whale shark – Rhincodon typus Location: Galapagos, Ecuador

We have now tagged 6 whale sharks with ultrasonic tags, and one individual with a satellite archive tag.