So in my opinion the following steps need to be taken in the following order:
Find out all the releases that have been linked to a species in the above list and fix these up by assigning them to an existing CAAB-registered species.
Once 1 is done, clean up the species table by removing all the entries listed above.
Add constraints to the Tag Release page so that users have to use the existing, cleaned-up, drop down menu listing all CAAB-registered species.
Obviously these steps will require quite some work, so an alternative, quick-fix, option for now would be to amend the Groovy file mentioned above by editing the getSpeciesName function to read: if (!spcode) {return "${name}"}.
Implemented a quick fix for species names entered manually instead of using the drop down menu, see last paragraph of https://github.com/aodn/aatams/issues/122#issuecomment-219897627: