True but you could also imagine a whole ship filled with New World fruit and veg like squash, tomatoes, papaya, peppers, the common bean was even a new thing. With that much stuff you could probably extend the life of a colony of fruit flies for a voyage. There were probably a dozen vectors for S. Eubayanus on a ship... I bet there were some crafty home brewers on every voyage as well considering fermented beverages were generally considered safer than water at the time.
There are some interesting experiments were people successfully create the theorized hybrid...
"Here, we generated de novo lager yeast hybrids by mating a domesticated and strongly flocculent Saccharomyces cerevisiae ale strain with the Saccharomyces eubayanus type strain. "
"Here, an allodiploid laboratory hybrid of S. cerevisiae and S. eubayanus was evolved for up to 418 generations on wort under simulated lager-brewing conditions in six independent sequential batch bioreactors."