Sightings during whale watching tours and studies of stranded individuals suggest the possibility of another form of Berardius in the Sea of Okhotsk inclusive of the coast of northern Hokkaido especially around Shiretoko Peninsula and off Abashiri, or to Sea of Japan off Korean Peninsula and north pacific and Bering Sea off Alaska. These whales are generally much smaller than known species (), darker in color, and inhabit shallow waters closer to coastal areas, enough to be trapped within fixed nets for salmon. Local whalers had called them kurotsuchi (= black Berardius) or karasu (= ravens); it is not known whether these terms are synonyms or identify two separate species. Genetic studies indicate that kurotsuchi are Berardius minimus, recognized as a distinct species in the 2010s.