This scientific review examined the harm done to fish by anglers’ hooks.
Hooks of all types can cause severe harm to fish. This includes hooking into the:
SINGLE HOOKS PENETRATE FISH DEEPER
"Single hooks are generally swallowed deeper or penetrate the tissues farther."
TREBLE HOOKS ENTANGLE IN GILLS
"However, treble hooks (on lures especially) are most deadly when entangled in the gills."
BARBED HOOKS ON LURES IMPALE ESOPHAGUS AND GILL ARCHES
Barbless hook "Barbed hooks on lures were impaled mostly in the esophagus and gill arches, whereas barbless hooks (on artificial lures) were embedded in the lower jaw. However, hooking on vital organs was almost always fatal, regardless of hook type."
FISH HOOKED IN VITAL ORGANS USUALLY DIE
"When fish are hooked in vital organs (e.g., esophagus, gills), mortality is generally high. For example, Warner (1979a) indicated that 96% of the mortality among deeply hooked Atlantic salmon, from which hooks were removed, occurred within 24h."
"Using a variety of terminal gear (single and treble hooks, artificial flies, and worm-baited hooks), Warner (1979a) reported that 44% of Atlantic salmon that died were hooked in the gills, and 24% were hooked in the esophagus. Overall mortality was 73% (77 of 106) when worm-baited hooks were swallowed; it was 57% (32 of 56) when hooks were left in place and 90% (45 of 50) when they were removed. Loftus et al (1988) reported 71.4% mortality for lake trout hooked in vital organs (e.g., gills, esophagus) compared with 6.9% for those hooked in the lower or upper jaw. Milne and Ball (1956) reported 100% hooking mortality among coho salmon hooked in the gills."
"Nuhfer and Alexander (1992) observed that 6l% of brook trout hooked deep in the gills or esophagus died."
"Hulbert and Engstrom-Heg (1980) observed that brown trout that "suffered the greatest mortality were hooked in the esophagus or stomach (46.6%) or gills (39.6%). However, because mortality was 59% when hooks were removed and 17.5% when they were not, it was recommended that hooks be left in place among deeply hooked fish whenever possible."
"Hooking in other vital organs can also be lethal; mortality among Atlantic salmon was 76% for fish hooked in the eye and 12% for those hooked in the gills (Warner, 1976)."
"Warner (1978) found that 61% of landlocked Atlantic salmon were hooked in the jaws. Although only 6% were hooked in the gills, mortality was 63% among those fish compared."
"Dotson (1982) determined that 75% of cutthroat trout were hooked in the lower or upper jaws, anatomical areas associated with low mortalities. Falk and Gillman (1975) concluded that severe hook damage and bleeding depended more on hook placement than on other factors, suggesting that species with "small, soft mouths" (e.g., Arctic grayling) tended to be hooked along the outer edges of the jaw, whereas voracious feeders such as northern pike engorged the lures completely and were hooked deeper."
"The overall mortality of tournament-caught largemouth bass was 66.7% when worm lures were swallowed and 7.1% when they were not (May, 1973). Siewert and Cave (1990) indicated that all bluegills hooked in the esophagus, gills, tongue, or eye died, whereas mortalities were 37.5 and 13% among fish hooked in the jaws and lips, respectively."