Dear MARMAM,
  My co-authors and I are pleased to announce a new paper on blue/fin whale hybrids:

Sightings and Satellite Tracking of a Blue/Fin Whale Hybrid in its Wintering and Summering Ranges in the Eastern North Pacific
 
Jefferson, Thomas A; Palacios, Daniel M; Calambokidis, John; Baker, C. Scott; Hayslip, Craig E; Jones, Paul A; Lagerquist, Barbara A; Jørgensen, Morten; and Schulman-Janiger, Alisa

Abstract
We report 20 photo-documented sightings of a blue/fin whale hybrid between 2004 and 2020, in its wintering and summering ranges in the Gulf of California, Mexico, and southern California, USA, respectively.  The whale was confirmed to be a hybrid by genetic testing using a reference dataset of non-hybrid blue and fin whales. It was also tracked by satellite for 28 days in 2015, showing its feeding range extended to the Big Sur area of central California.  Information is presented to assist in field identification of blue/fin whale hybrids.

The paper is available for open-access download:

Best wishes,
Tom Jefferson
Clymene Enterprises