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can be more extensive than with single or double hooks. Other problems encountered when using treble and double hooks are the extended time/air-exposure required to remove multiple hooks, increased chance of entanglement in dip nets, and the presence of multiple puncture wounds in fish. Barbs and tanges generally increase the severity of hook injury by inflicting greater tissue damage and bleeding than barbless hooks. Additionally, barbs can increase handling time and exposure to air by making it difficult to remove hooks, which significantly influences rates of mortality. Barbed hooks can easily be modified into barbless hooks by crimping with pliers. Not removing hooks in fish that are released can facilitate infection, and depending on the metal and anatomical location of impalement, may remain inside the fish for months or years. If hooks cannot quickly (< 30 sec) be removed without causing significant tissue damage, the fish should be immediately euthanased or released by cutting the line as close as possible to the hook. 2. Line, rod, and reel A major consideration for selection of different lines, rods, and reels and their effects on fish welfare is the match of the gear to the environment, species, and size of fish being targeted. Balanced gear ensures the angler has control over the fish, which facilitates best handling procedures by reducing the number of break-offs, minimising the duration of capture, and by reducing rates of injury. Fish that break off may suffer from being semi-permanently impaled by a hook with a line trailing behind. Light gear promotes breakoffs and may increase the duration of capture, which also negates conservation merit if the fish subsequently dies. 3. Live bait, lures, and flies Different rates of deep hooking, foul hooking, and mortality have been observed between baits, lures, and flies, but there does not appear to be a general pattern applicable for all species and methods of capture. Rather, differences in injury appear to be related more to the presentation of the tackle, or type and size of hook being used. Where live bait is used, the welfare of the fish presented as live bait may be compromised if humane procedures are not followed (see Euthanasia).It is common practice in some fisheries, such as marlin (Istiophoridae) fishing, to bridle live fish. The process involves stitching the live bait, usually through the orbits, to a large hook and towing or drifting it behind a boat. Live baiting is not essential to capture most predatory fish, and is discouraged if fish welfare is to be considered. 4. Landing nets, keepnets, live wells, and gaffs Landing nets are commonly used by recreational fishers to assist in handling fish during capture. Because landing
nets can extend the time required to remove hooks by becoming entangled with the hook, line, and fish, they should only be used when necessary. All nets cause some degree of pectoral and caudal fin abrasion, and may cause skin abrasion, which increases the risk of fungal infection in released fish. It has been found that 4mm diameter rubber, and 1mm knotless nylon nets were most effective at reducing skin damage and mortality rates, while coarse and fine-knotted nets caused the most frequent and traumatic injuries. Keepnets, live wells (also called bait tanks), and similar devices such as ‘tuna tubes,’ are occasionally used to store live fish. Keepnets and live wells prolong the negative influences of catching fish by hook-and-line, in that the capture is followed by confinement. Other retention devices such as stringers and fish baskets can result in significant injury and can increase rates of postrelease mortality. Tuna tubes were developed by marine recreational fishers to maintain live bait species that normally die in bait tanks. Live bait species such as skipjack tuna, (Katsuwonus pelamis) ventilate their gills by swimming forward with their mouth open, a strategy called ram ventilation. In a bait tank, their ability to ventilate is limited. A tuna tube pumps water through a pipe in the direction of the fish’s mouth and ventilates the fish in a confined area. While tuna tubes reduce bait mortality, the confinement does not improve fish welfare. A gaff is made of a pole with a sharp hook fixed at the end which is used to penetrate the flesh and bone of a fish. The hook may detach from the pole when using a ‘flying gaff.’ Gaffing is used to control large (> 5 kg) fish when landing nets are too small, and the accuracy of delivering a stunning blow is physically difficult, such as may occur over the side of a boat in rough seas. Gaffed fish show short-term avoidance swimming of a particularly strenuous nature. Gaffing is not recommended because injuries caused by gaffing often result in significant bleeding so that exsanguination (bleeding out) may precede stunning or death.
Euthanasia The principles of humane slaughter are the same for all animal species. These are: rapid loss of consciousness without any avoidable stress so that the animal feels nothing, followed by death as assessed by loss of brain function without regaining consciousness. Loss of consciousness is often induced in a commercial setting by either stunning (percussive or electrical), or chemically using anaesthetics. Death of unconscious animals can be achieved by the destruction of the brain or by anoxia caused by exsanguination/bleeding-out. The time to loss of consciousness in fishing is the period during which fish may suffer.
Table 2: Common methods of euthanasia used by recreational fishers that are deemed acceptable or unacceptable on animal welfare grounds Recommended
Acceptable if unconscious a
b
Pithing Percussive stunning (blow to head) and pithing (iki jime) or exsanguination (bleeding) or decapitation (neck cut) Decapitation Exsanguination
Unacceptable Asphyxiation c (removal from water) Hypothermia (ice slurry or freezing) Pithing, decapitation, or exsanguination without prior percussive stunning Percussive stunning without pithing, decapitations, or exsanguination
a
Close et al (1997) Difficulty in administering accurate strike makes pithing unacceptable without unconsciousness c Poly et al (2005) b
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