Holes in a fish's mouth, caused by anglers removing a hook, handicaps a fish's capability to catch other fish. They are not able to suck in prey fish. Many species of fish feed this way, including victims of anglers, such as bass, salmon, and trout.
Researches working in Canada caught, using a rod and line, ten shiner perch. A further ten were caught by a net. They found that the rod caught fish were significantly less able to eat properly.
“Fishing is a popular and lucrative sport around the world and, in some cases, may contribute to declining fish stocks.”
“Using high-speed video and computational fluid dynamics (CFD), we asked whether injuries around the mouth caused by fishing hooks have a negative impact on suction feeding performance (measured as maximum prey velocity) of the commonly angled marine shiner perch.”
“Injury-induced hole in the buccal cavity wall reduced the pressure gradient during mouth expansion, thereby reducing the velocity of water entering the fish's mouth.”
“Fishing injuries in nature are likely to depress feeding performance of fish after they have been released.”