Breach at the horizon! Why do whales breach?

A recent study investigated whether environmental parameters, social factors, and anthropogenic disturbance can have an effect on fin whale breaching in the Mediterranean Sea.

Breaching is frequently reported for many large cetacean species, and is iconically linked to humpback whales jumping out of the water and slapping back onto the surface, but, even if more rarely, also the Mediterranean fin whales occasionally breach.

Using data collected between 2012 and 2020 within the Fixed Line Transect Monitoring Network coordinated by ISPRA and the University of Tuscia along the ferry route from Italy to Spain, breaching events were analyzed with respect to season, chlorophyll concentration, sea state, group size, fin whale frequency, distance between a breaching event and the closest whales, distance from the observation platform, and maritime traffic.

Breaching events were recorded in almost 4% of fin whale sightings –confirming it as a rare but regular behavior -, and were especially recorded during summer and fall and never during winter.

The most significant variables correlated with breaching were the distance between whales, likely related to socialization and communication purposes, while maritime traffic seemed to act as inhibitory factor as most of the breaching events occurred farer from the observation platform, and the mean vessel number in the area of fin whale breaching was lower than the traffic recorded during fin whale sightings without breaches.

On the other side, there was no evidence that chlorophyll concentration differed between the location of breaching events and the surrounding areas. Breaching events occurred mostly in calm sea conditions, and no juveniles were involved during breaching.

In general, breaching was indicative of favorable environmental and social conditions for the species and only in one case, breaching was performed after a near collision with the ferry in the waters of the Spanish Cetacean Migration Corridor.

The upcoming data collected within the FLT Med Net and the Life CONCEPTU MARIS will help further enhancing the understanding of this amazing behavior of the Mediterranean fin whale.

This study was conceived with the important contribution of Professor Dario Angeletti and the authors are deeply grateful for his everlasting example of professionalism, friendship, and enthusiasm.

Campana I., Farace I., Paraboschi M., Arcangeli A. 2023. Analysis of environmental, social, and anthropogenic factors as potential drivers of breaching behavior in the Mediterranean fin whale. Marine Mammal Science https://doi.org/10.1111/mms.13000.