Anglers were deployed to catch 1,087 trout on 45 fishing trips, from the Bois Brule River in Wisconsin, United States. 3.5% of the fish died. Of these, 85% died immediately, more than 90% within 24 hours.
GILL HOOKING DEATHS
When trout were hooked in the gills, over a third of them died.
OTHER HOOKING DEATHS
Death was also caused by hooking in the eye, jaws, body, and deep hooking in the mouth.
Trout bled the most when fighting capture. Three quarters of the trout that died were bleeding noticeably.
SEVERE EYE INJURY
The eyes of 10% of the fish were seriously damaged:
JAWS TORN AWAY
Jaw injuries were most commonly the tearing away of the jaw bone, often accompanied with tearing of the cheek.