Ocean Trawler Doesn't Spawn Malbatross (?)

Unless I'm getting very unlucky, I think the fish that are caught by the Ocean Trawler in the Malbatross shoal won't spawn Malbatross.

Unsure if intentional since Malbatross can attack Ocean Trawlers if it has fish in it, but that won't happen unless Malbatross was already there since they don't spawn as mentioned above.