Study Reveals Behavioral Patterns of the Blue Shark and the Impact of Boat Noise on the Species

LISBON, Portugal - Feb. 20, 2025 - PRLog -- Innovative research led by MARE - Marine and Environmental Sciences Centre has unveiled critical insights into the behavior of blue sharks (Prionace glauca) and the impact of boat noise on their natural activities. Conducted off the picturesque coast of Arrábida Natural Park, in the Atlantic coast of Portugal, the study employed remote baited cameras to observe these elusive predators in their natural habitat. Noélia Ríos' PhD thesis, within the INFORBIOMARES project, highlights these findings, now published in the renowned journal Marine Ecology Progress Series.

Blue sharks, known for their sensitivity, have been notoriously difficult to study in the wild. However, the researchers' cameras documented the behavior of 79 sharks, revealing fascinating differences between juveniles and adults based on the season and proximity to the coast.

The study discovered that juvenile sharks prefer shallower waters during spring, coinciding with their breeding season. According to Noélia Rios, a PhD student from ISPA – Instituto Universitário, this finding "highlights the importance of the Lisbon Canyon near Arrábida Natural Park as a potential nursery area for blue sharks, prompting calls for the protection of these crucial submarine canyons".

Moreover, the research, supervised by researcher Gonçalo Silva, uncovered that boat noise significantly alters the sharks' behavioral patterns, suggesting a hidden effect on their feeding efficiency. This groundbreaking discovery paves the way for further studies to explore the broader implications of underwater noise pollution.

Sharks play a pivotal role in maintaining the stability and health of marine ecosystems. Excessive commercial fishing, both targeted and bycatch, exerts immense pressure on shark populations, causing ecological imbalances with far-reaching consequences.

The blue shark remains one of the most captured shark species worldwide, with the IUCN classifying it as 'Near Threatened' in 2019. In Portugal, it is the primary target of the surface longline fleet, a method that often inadvertently traps sharks lured by bait.

Original scientific paper: https://doi.org/10.3354/meps14765