There are various fish that are sold as ‘skate’. Vast majority are thornback rays I think, but you might be eating smalleyed ray, blonde ray or other variations. I think your brother in law is right - the commercial catching of the ‘common’ skate is either banned or very limited as it isn’t...
After reading this thread yesterday, I was informed we were going to the local Beefeater in Burgess Hill (wouldn't have been my choice but I was stuck in traffic and decisions were made etc) for dinner, so I ordered to 'freshly hand battered haddock, chunky chips and garden peas' or however the...