During the period of January to March in 2007, the CRAM made a study on the customs of the populations of cetaceans and the impact of acoustic contamination in their communities by means of systems EAR (“Ecological Acoustic Recorder”), developed thanks to an agreement of investigation between Foundation CRAM and the Oceanwide Science Institute de la Universidad de Hawaii. It’s a pioneering system in Europe that exists only 23 units in the world and that has the capacity to detect and to store a programmable frequency between the 0 and the 24 kilohercios (kHz), with which it adjusts to the necessities of the studies of bioacústica with cetaceans.
 

equipped with a hydrophone that its use in drag as in static allows as much and with systems EARS that were installed to a certain depth to register sounds in longer time.

The study began fixing systems EAR at two fixed weather stations to the south of Tenerife and north of Gran Canaria. In addition, a series of routes previously established with the hydrophone was made in drag, for the registry and identification of different populations of cetaceans. Also the hydrophone in static modality for the registry of activity of cetaceans was used that emit low sound; this device has capacity to detect and register a rank of frequencies that goes of 5 Hertz. (Low frequency), to 200 kHz (high frequency).

The location of the EARS allowed registering the sounds caused by the activity of the different cetacean’s populations and the caused one by the antropic activity in the existing channel between the two islands, where a high marine traffic exists. The result was the registry of 270 archives of sound with a frequency of sampling of 64,000 Hertz.

The recordings revealed that the “clicks” are more abundant in hours to get late and during the night, which suggests it presence of odontocetos in this area is probably tie to displacements of daily character towards deep waters in the evening, remaining in the zone during the night. This characteristic suggests it zone of sampling could be used by the odontocetos like area of nocturnal feeding.

With regards to the whistles, its presence was smaller to clicks of ecolocalización, although its tendency follows a same pattern, indicating that the emission of whistles is coincident with the ecolocalización activity. The whistles are more abundant during the dusk and very low or absent during the night. These results indicate that the behavior that predominates during the hours of light and specially in the evening is a social character. Thus, the acoustic activity shows social behaviors during the day, feeding during the hours at night and both during afternoon.

The amount of contributed registries of sound after the campaigns made with canary water systems EARS did possible to finish the detection of misticetos, to identify the different species from odontocetos and to finalize the analysis of the noise at the habitat.

Watch the final report in PDF format:

Informe de Campaña de Bioacústica (IN SPANISH) [Size 250 kb]

Divers setting the EAR device