The 2003 CD Learn & Play: Songs for Young Children by Beth and Scott Bierko has the baby shark song.


Purchase here: https://www.amazon.com/Learn-Play-Beth-Scott/dp/B00009952O


Scott Bierko wrote in an email dated 15 Aguust 2019:   

We did not write it [baby shark]. We heard it while we were setting up to do a show
at a summer camp, Camp Kiwi, in Rockland County, NY. I’m going to guess
that was around 1996-98. A counselor was singing (and moving with it) it
with her kids. We thought it was hilarious.