The researchers studied bycatch in bottom trawl fisheries off the southern coast of Portugal. They looked at what species were caught unintentionally while fishing for shrimp and fish. They found that a lot of different species were caught, including bony fish and crustaceans. The shrimp trawlers had more diverse bycatch than fish trawlers. Factors like depth, fishing gear, and season influenced the amount of bycatch and discards.