This project will improve animal welfare in wild-capture rod-and-line (R&L) fisheries for Atlantic bluefin tuna (Thunnus thynnus L.). By improving welfare, the project intends to minimise the environmental impacts of fishing through improvements to sustainability and product quality. Catching fish one-by-one gives the opportunity to maintain welfare and quality at the individual level. From a scientific point-of-view, stressors and responses can be individually monitored throughout the whole capture process and post-mortem phase. Due to the high dependency of ABT price on quality (Nøttestad et al, 2020), R&L fishers should be motivated to promote animal welfare as a means of maximising profits. The environmental impacts of this gear type are also relatively low (Gilman, 2011). Norwegian R&L fishing for ABT is therefore well placed to transition towards a welfare-conscious fish capture method. However, knowledge gaps exist that hinder this transition: 1. Lack of knowledge of the animal welfare impacts of capture and slaughter; 2. Sub-optimal handling practices and limited processing infrastructure; 3. Limited understanding of ABT behaviour and distribution; and 4. Bycatch and escape rates are unknown. Project Goal: Promote ethical capture & slaughter, sustainability and catch quality in an Atlantic bluefin tuna rod & line fishery by developing animal welfare conscious capture and handling practices. Sub-objectives: a. Improve ABT welfare during capture and slaughter by characterizing stressors and responses, and by testing mitigation measures. b. Improve current knowledge of the effect of pre-mortem capture and slaughter stress on post-mortem meat quality in ABT. c. Develop and test systems to humanely stun ABT and thereby improve animal welfare and product quality. d. Improve the sustainability of Norwegian ABT R&L fishing by understanding catch efficiency, escape rates, bycatch rates and fuel consumption, and by testing mitigation measures. e. Promote sustainability, good welfare and product quality in R&L tuna fisheries by providing best practice guidance for capture, handling, slaughter, storage and quality control.

Where practical, tuna will be fitted with heart rate and temperature tags, following the procedure described by Rouyer et al, 2023 (see attached). That is, “ABFT show tonic immobility when air-exposed and placed on their side, facilitating tagging procedures. The site of tagging was the fleshy area below the operculum, into muscles associated with the cleithrum that, in ABFT, are in close proximity to the heart, is rich in fat and thick enough to hold an implanted tag (Figure 1a). Tag placement was by a [disposable 15 - 150 mm atraumatic] trocar with a cannula that had an internal diameter similar to the tag diameter.” A subset of fish (n = ~45), will be assessed the effects of captive towing on the animal's recovery. These will be secured by a hook/rope through the lower mandible and towed at 2-4 knots for a period of upto 1 hour, before being killed. Today's killing methods in the fisheries vary due to practical reasons. In many cases, bleeding is used as the main killing method. Three methods of killing tuna will be investigated in this project during 2024-25: 1. Bleeding only - The typical killing method aboard commercial/recreational fishing boats is to bleed them (without stunning or brain spiking), via severing the blood vessels supplying the gills, as well as the lateral blood vessels in the pectoral fin recess. From our dialogue with commercial and recreational fishers, this appears to usually be done in the water, with the fish bleeding out before being hauled aboard the vessel. 2. "Ike jime" (spiking & pithing) - at the soonest opportunity, the animal is killed by spiking the brain, immediately followed by bleeding as above. The spinal cord is then destroyed by inserting a wire into and along the length of the spinal column. This procedure can only be conducted safely and effectively with the fish aboard the fishing vessel. 3. Percussive stunning/killing and bleeding - the brain is destroyed by captive bolt device, to be developed as part of this project, immediately followed by bleeding as above. The effectiveness of this as a stunning/killing method will be assessed in WP2: “Stunning” – see attached Project Description for further details. Blood samples will be taken from the lateral blood vessels in the pectoral fin recess immediately after the killing method has been applied.

We need to study wild animals because we are simulating wild-capture commercial fisheries.