The following pages are from the Marine Mammal Inventory Report (MMIR) compiled by National Marine Fisheries Service (NMFS). Facilities holding marine mammals in the USA for exhibition are legally required to report all births and deaths to NMFS and the report is publicly available upon request through the Freedom Of Information Act.
You may notice that some "Cause Of Death" entries are missing or written as pending despite taking place years ago. NMFS doesn't enforce facilities on reporting the "Cause Of Death" so they frequently go unreported.
This version of the MMIR was last updated July 2016. There have been additional deaths at Sea Life Park since then. You can view the full Marine Mammal Inventory Report here. You can view the following pages (of just the Sea Life Park entries) in its original PDF form here. You can also request the most recent version of the report through the Freedom Of Information Act.
In addition to this, Sea Life Park was opened prior to the making of the MMIR, so the births, deaths, and wild captures prior to this are not reported on these reports. With the help of CetaBase, we've compiled a list of some of the additional animals that were referenced in studies, the original animal trainer's memoir, and news articles (attached at the bottom of this page).
It's unfortunately very likely that there are even more animals that went unreported.