SPCA New Zealand
Advice & welfare

Best practice recommendations for recreational anglers

Humane ways to kill finfish intended to be eaten

Fish have the capacity to feel pain, fear and distress. They possess pain receptors, which are the hardware to detect if something is painful. They also behave differently, and show changes in their brain activity when exposed to painful stimuli. Furthermore, after fish have been exposed to painful events, painkillers have proved to be effective in restoring normal behaviour.

Fish are at a higher risk of experiencing poor welfare during activities such as recreational fishing, which involves capture, handling and slaughter of fish. Ensuring fish are killed humanely will help to minimise pain and suffering. A humane death occurs instantaneously or is preceded with a stunning method, which causes instant or rapid unconsciousness. Humane killing avoids unnecessary stress and will also improve the flesh quality of your catch.

Three important things to consider when dispatching finfish is to 1) choose the right method, 2) count the seconds, and 3) check the method was successful. To increase confidence that you have humanely dispatched your catch, you should always use a follow up method such as chilling.

1. CHOOSE the right method

Do's

  • Mechanical Spiking
    Spiking the brain (also referred to as the iki jimi method) will kill fish immediately and is an appropriate method of humanely killing restrained finfish by experienced anglers. To ensure the correct amount of force is applied for an effective kill and that the spike reaches the brain as quick as possible, it is recommended to use a tool specialized for the method. For example, spring loaded or elastic powered spikes make the process quicker and more effective. It is important to know your species, as the location of the brain will differ amongst them (visit www.ikigun.com/pages/brain-locations for the spike points of common species found in NZ).
    (NOTE: Manual spiking i.e. using a sharp object and relying solely on your own physical strength, is not as recommended as the process is slower and effectiveness can vary with fatigue and human error.)
  • Percussive Stunning
    Knocking a fish on the head with significant force, using a heavy club or other blunt instrument, will render a fish unconscious. It is important to aim just above the eyes to ensure impact on the brain. The force required will depend on the size of the fish. This method is considered a stunning method and therefore a follow-up method needs to be applied immediately (within 10 seconds) after stunning to ensure the death of the fish. Follow up methods can include cutting gill arches (on both sides of head) to cause bleeding or spiking the brain.
    (NOTE: Confidence is key. If you are new to these methods, please ask for help from an angler experienced with the techniques, until you are practiced and skilled with the method.)

Don'ts

  • Dying slowly in air or a bucket of water
  • Decapitation
  • Live chilling
  • Gill cut without prior stunning

These methods have been deemed unacceptable due to the potential of prolonged pain, fear and stress prior to unconsciousness. Some species of fish left out of water to be deprived of oxygen can take up to 5 hours to cease gill movements. Studies show that when immersed in ice water the brain of fish remain active, even though all physical reactions stop. Decapitation (without prior stunning) is not considered humane, as the brain continues to function for a considerable amount of time and the sensory capacities of fish during this period remains unclear.

2. COUNT the seconds

Timing is crucial. Emersion in air is very stressful for fish. Gravity places pressure on their internal organs, gills collapse, skin desiccates, they experience sudden thermal and light intensity changes, and suffocation. The least amount of time the fish is out of the water the better (preferably <15 seconds). Make sure you have all your equipment ready!

3. CHECK the method worked

Observe your fish continuously (up to 30minutes after killing) to ensure the methods worked. Indicators of consciousness to look out for include:

CONSCIOUS

UNCONSIOUS

The eyes roll, in an attempt to stay upright, when the body of the fish is rolled from side to side (figure A)

The eyes are fixed, relative to the head, when the body of the fish is rolled from side to side (figure B)

The opercula (gill covers) are moving

(except in tuna and other ram ventilators)

The opercula (gill covers) are not moving

(except in tuna and other ram ventilators)

Behaviours, reflexes and responses present

Behaviours, reflexes and responses absent

The “eye roll” reflex in (A) a live cod and (B) a dead cod (Kestin 2002).
The “eye roll” reflex in (A) a live cod and (B) a dead cod (Kestin 2002).

References

  • Brown, C., & Dorey, C. (2019). Pain and Emotion in Fishes – Fish Welfare Implications for Fisheries and Aquaculture Pain and Emotion in Fishes – Fish Welfare Implications for Fisheries and. 8(2), 175–201.
  • Kestin, S. C. (2002). Protocol for assessing brain function in fish and the effectiveness of methods used to stun and kill them. 1999, 113–118.
  • Lines, J. A., & Spence, J. (2014). Humane harvesting and slaughter of farmed fish. OIE Revue Scientifique et Technique, 33(1), 255–264. https://doi.org/10.20506/rst.33.1.2284
  • Poli, B. M., Poli, B. M., & Zootecniche, S. (2009). Farmed fish welfare-suffering assessment and impact on product quality Farmed fish welfare-suffering assessment and impact on product quality. https://doi.org/10.4081/ijas.2009.s1.139
  • Roth, B., Moeller, D., Veland, J. O., Imsland, A., & Slinde, E. (2002). The Effect of Stunning Methods on Rigor Mortis and Texture Properties of Atlantic Salmon (Salmo Salar [Article]. Journal of Food Science, 67(4), 1462–1466. https://doi.org/10.1111/j.1365-2621.2002.tb10306.x
  • Roth, Bjorn, Birkeland, S., & Oyarzun, F. (2009). Stunning, pre slaughter and filleting conditions of Atlantic salmon and subsequent effect on flesh quality on fresh and smoked fillets [Article]. Aquaculture, 289(3), 350–356. https://doi.org/10.1016/j.aquaculture.2009.01.013
  • Sharp, T., Saunders, G., Australia. Bureau of Agricultural and Resource Economics and Sciences., Australia. Department of Agriculture, F., & Industry & Investment NSW. (2011). A Model for assessing the relative humaneness of pest animal control methods (Issue June).
  • Sloman, K. A., Bouyoucos, I. A., Brooks, E. J., & Sneddon, L. U. (2019). Ethical considerations in fish research [Article]. Journal of Fish Biology, 94(4), 556–577. https://doi.org/10.1111/jfb.13946
  • Sneddon, L. (2002). Anatomical and electrophysiological analysis of the trigeminal nerve in a teleost fish, Oncorhynchusmykiss [Article]. Neuroscience Letters, 319(3), 167–171. https://doi.org/10.1016/S0304-3940(01)02584-8
  • Sneddon, L. (2003). The evidence for pain in fish: the use of morphine as an analgesic [Article]. Applied Animal Behaviour Science, 83(2), 153–162. https://doi.org/10.1016/S0168-1591(03)00113-8
  • Sneddon, L., & Wolfenden, D. (2018). Ornamental Fish ( Actinopterygii ) . Companion Animal Care and Welfare, 7, 440–466. https://doi.org/10.1002/9781119333708.ch22
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