Gulls dont fish, they scavenge, they are sea going carrion birds, a cormorant or gannet dives and catches fish, a gull feeds off of floating sewage and dead things. Folk try to big the gulls up as noble birds up with the Perigrine, fact is, they are winged longtails with an uncanny ability to hit cars with shite. IMHO we are overpopulated with gulls they have increased in number as the food source became available, that source is now dimishing so they should fall back in number to their original population. That is natures way.
Gulls are problematic
http://douglas.gov.im/index.php/news/council-news/item/2408-feeding-of-animals-and-birds-council-clarifies-amended-byelaw-proposal