Identifying Whales Through Flukeprints for Understanding Migration Patterns and Calf Mortality

Rhianna Torres, Bryan Loya Acevedo, Jada Gaines, Dr. Clare Steele, and Dr. Cynthia Wyels

Abstract

The Hawaiian ‘Au’au Channel, between the islands of Maui, Lanai and Molokai, is a preferred breeding and nursery ground for the North Pacific humpback whale (Megaptera novaeangliae). Humpback whales migrate up to 5,000 miles a year from their breeding to feeding grounds. Approximately 60% of the North Pacific humpback population migrates from the feeding grounds in Alaska to Hawaii, with 80% of those making their wintertime home in the ‘Au`Au Channel. However, there have been examples of Humpbacks making the journey to Hawaii from other parts of the world such as a lone whale from Japan that was spotted in Hawaii in 1991. This research contributes to an enhanced understanding of potentially changing humpback whales migration patterns and calf survival rates during their first migration. Mom and calf pairs were identified and followed by a research vessel (NMFS #22750-01). Fluke pictures were taken of any encountered maternal humpback that breached. Mother and calf pairs were necessary for this study in order to distinguish the mothers from any male counterpart. The fluke pictures were then sorted and graded, with the highest quality pictures being submitted into Happy Whale, a ‘flukeprint’ database for whales, for potential matches with past or future sightings of individual whales. Comparing the flukeprints captured from the 2022 cohort with recognized whales from previous or future years will allow us to categorize individual whales by migration choices as well as to better assess calf mortality during the first migration.

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