Estimating Discard Mortality in Commercial Fisheries without Fish Dying: A 3R Challenge.

Globally, it is estimated that around 10% of the fish that are caught are discarded. This is considered to be a wasteful human marine activity since these fish are often dead or dying. To reduce the high discard rates of commercial fisheries, the European Union (E.U.) has enacted a landing obligation that includes the ability to exempt "species for which scientific evidence demonstrates high survival rates". Therefore, discard survival studies (henceforth DSSs) have become one of the most politically prioritized fisheries research areas in European fisheries. International expert groups have produced guidance reports to promote best practices and to harmonize the methodologies. Nevertheless, there has not been any focus on how to implement animal welfare (AW) regulations experimentally. Discard survival studies are "frontrunners" in fisheries science research areas that are embedded by animal research welfare requirements and are expected to be more restrictive in the future because of an increased public focus on fish welfare. This paper focuses on AW regulations in relation to conducting DSSs, but the outreach is much broader. We investigate experimental procedures by bringing in relevant examples, using output results, and relating this information to relevant AW guidelines and regulations by focusing on implementing 3R principles.

Visualization of intrathecal delivery by PET-imaging.

BACKGROUND: Intrathecal (IT) delivery is useful in both basic research and clinical treatments. Here we aim to test a new minimally invasive distribution route to the subarachnoid space (SAS) and the flow of IT administrations. We placed a radioligand into SAS during positron emission tomography (PET) scanning as a proof of concept. NEW METHOD: We injected a 11C-labeled PET-tracer using a surgically placed catheter in the cisterna magna of anesthetized female pigs. The pigs were scanned for 1.5-2 hours in a PET/CT-scanner. The pressure from continuous infusion of artificial CSF (aCSF) promoted distribution of the tracer. The procedure was done under continuous intracranial pressure (ICP) monitoring. The catheter was made accessible both by externalization through the skin and through a subcutaneously placed sterile titanium port connected to the catheter. After image reconstruction, we used PMOD software to assess the tracer distribution throughout SAS. Internalisation of the catheter to a port enables survival studies. Previous studies performing ventriculography have placed a catheter trough brain cortex and parenchyma; such procedures may affect any behavioural or neurological evaluation, and have an increased risk of bleeding per- and post-operatively (Kaiser & Frühauf, 2007). RESULTS: The PET-CT visualized tracer was evenly distributed in the SAS. Furthermore, the ICP measurement made it possible to adjust infusion speed within acceptable pressure levels. CONCLUSION: This new method can be useful for testing distribution of PET-tracers, antibiotics, chemotherapeutics and a wide range of other pharmaceuticals targeting the CNS and spinal cord in large animal models, and potentially later in human.

Muscle Tissue Saturation Compared With Muscle Tissue Perfusion During Low Blood Flows: An Experimental Study.

OBJECTIVE: To investigate whether changes in muscle tissue perfusion measured with positron emission tomography would be reflected by parallel changes in muscle tissue oxygen saturation (StO2) measured using near-infrared spectroscopy during high and low blood flow levels achieved using cardiopulmonary bypass (CPB) in an animal model. DESIGN: A prospective, randomized study. SETTING: Research laboratory, single institution. PARTICIPANTS: Eight pigs (69-71 kg). INTERVENTIONS: In anesthetized pigs, normothermic CPB was established with a blood flow of 60 mL/kg/min for 1 hour. Thereafter, a low blood flow of either 47.5 or 35 mL/kg/min was applied for 1 hour followed by a blood flow of 60 mL/kg/min for an additional hour. Regional StO2 was measured continuously by placing a near-infrared spectroscopy electrode on the skin above the gracilis muscle of the noncannulated back leg. Muscle tissue perfusion was measured using positron emission tomography with 15O-labeled water during spontaneous circulation and the different CPB blood flows. Systemic oxygen consumption was estimated by measurement of venous saturation and lactate levels. MEASUREMENTS AND MAIN RESULTS: The results showed profound systemic ischemia during low CPB blood flow. StO2 remained high until muscle tissue perfusion decreased to about 50%, after which StO2 paralleled the linear decrease in muscle tissue perfusion. CONCLUSION: In an experimental CPB animal model, StO2 was stable until muscle tissue perfusion was reduced by about 50%, and at lower blood flow levels, there was almost a linear relationship between StO2 and muscle tissue perfusion.