Monk seal acoustic examine quadruples recognized name varieties and detects novel communication technique

New analysis led by UH Hawaiʻi Institute of Marine Biology (HIMB) Marine Mammal Research Program (MMRP) has drastically elevated the understanding of Hawaiian monk seal (Neomonachus schauinslandi) underwater sound manufacturing, revealing a vocal repertoire way more advanced than beforehand described.

Published in Royal Society Open Science, the examine analyzed 1000’s of hours of passive acoustic knowledge and recognized 25 distinct underwater vocalizations, a dramatic enhance from the six calls beforehand recognized from seals in human care.

The workforce additionally discovered that Hawaiian monk seals produce these low-frequency calls all through the day, with constant vocal varieties detected throughout the Hawaiian Archipelago and better calling charges at websites with better seal abundance. This breakthrough discovery establishes a baseline for understanding the acoustic world of this extremely endangered and endemic Hawaiian species.

Key discoveries of a hidden world

“We discovered that Hawaiian monk seals—one of the world’s most endangered marine mammals—are far more vocal underwater than previously known,” mentioned Kirby Parnell, lead creator of the examine and a Ph.D. candidate with MMRP.

“By analyzing over 4,500 hours of recordings from across the Hawaiian Archipelago, we identified more than 23,000 vocalizations representing at least 25 distinct call types.”

The examine, which deployed passive acoustic recorders at 5 key monk seal habitats from Molokaʻi to the distant Northwestern Hawaiian Islands, uncovered:

• Expanded vocal repertoire: Researchers recognized 20 beforehand undocumented calls.
• Novel communication technique: The analysis gives proof that monk seals can mix totally different vocalizations collectively, creating “combinational calls”—a communication technique by no means earlier than reported in any pinniped species.
• A foraging name: The workforce found one novel elemental name sort, the Whine, produced throughout foraging, representing solely the second recognized instance of a seal species utilizing vocalizations whereas pursuing prey.

“We were surprised by the sheer diversity and complexity of monk seal vocalizations,” notes Parnell.

“The discovery of combinational calls, where seals link multiple call types together, suggests a previously unknown level of complexity in pinniped acoustic communication. Finding a new call type—the Whine—associated with foraging behavior was also unexpected and suggests that monk seals may use sound not only for mating or socializing, but possibly for foraging purposes as well.”

Implications for conservation in Hawaiʻi

The Hawaiian monk seal is Hawaiʻi’s solely endemic marine mammal and a treasured a part of Hawaiian tradition. This analysis is important for the species’ conservation, significantly within the face of accelerating ocean noise.

“This research provides the first comprehensive description of free-ranging Hawaiian monk seal underwater sound production, an important step toward understanding how they use sound for critical life-history events,” explains Lars Bejder, Director of MMRP, Professor at HIMB, and co-author of the examine.

“Because their vocalizations overlap with the same low-frequency range as many human-generated sounds (e.g. vessel noise), this work also helps us evaluate how ocean noise may affect communication, reproduction, and behavior in this endangered species.”

These outcomes lay the inspiration for utilizing passive acoustics to watch monk seal populations throughout their huge vary and to guard their acoustic habitats as human exercise persists in Hawaiian waters.

Future analysis will decisively hyperlink these documented vocalizations to particular Hawaiian monk seal behaviors, reminiscent of foraging, swimming, social interactions, and copy.

A important subsequent step includes creating automated detection programs to watch the seals’ acoustic exercise extra effectively and non-invasively, offering a strong, long-term device for conservation administration and ecological understanding.