An Etymological Dictionary of the German Language/Annotated/Walfisch
Walfisch, masculine, ‘whale,’ from the equivalent Middle High German walvisch, Old High German walfisc, masculine. The first component was originally sufficient to designate a whale; compare Modern High German, Middle High German, and Old High German wal, Anglo-Saxon hwœl, Old Icelandic hvalr, masculine, ‘whale.’ The early history of Teutonic hwala-, ‘whale’ (to which Middle High German walre, Old High German węlira, ‘whale,’ is allied), is obscure. — Walroß, neuter, ‘walrus,’ from the equivalent Danish hvalros, as well as Narwal and Wels, are from the same root.