Yes, humans in previous generations wouldn't even bat an eyelid at the death rates. it wasn't long ago that people used to willingly go on boat journeys even though 10% of the passengers would typically die on the way
Deaths at sea definitely occurred. Credible accurate records don't seem to be available however, as this article's abstract notes:
Farley Grubb, "Morbidity and Mortality on the North Atlantic Passage: Eighteenth-Century German Immigration" (1987).
https://www.jstor.org/stable/204611
"Coffin ships" that carried the Irish fleeing the potato famine to America were notorious for their death rate and generally bad conditions. Of course, this was an already weakened population of passengers.
Source? Seems highly implausible (in general).