Empirical evidence for pain in fish: Wider impact of fish welfare in scientific, regulatory, public and cultural contexts
In order to afford an animal protection there has been a focus on whether that species can suffer and thus studies have sought to determine the capacity for experiencing pain. It is generally accepted mammals have this ability but aquatic species have been subject to much debate. This presentation will define animal pain and focus on the journey to confirm fishes experience pain from describing nociceptors through to whole animal behavioural changes. Nociception is the detection and reflex response to potentially painful, damaging stimuli, however, pain encompasses the psychological aspect of longer-term suffering and discomfort. Using selective attention approaches, fish experiencing a painful stimulus do not show normal fear or anti-predator behaviour thus this suggests the pain experience is important and takes priority over competing stimuli. We now use large numbers of fishes in experimental procedures across the globe so current research has aimed to assess laboratory fish welfare by developing an automated intelligent monitoring system that can accurately detect health status in zebrafish. Further if adult zebrafish experience pain we should seek to employ 3Rs ethics and replace them with unprotected larval forms based upon the premise they are not sufficiently developed enough for pain to occur. This body of work has demonstrated the capacity for pain in fish and as such this has had significant implications for the treatment of fish and altered the public perception of what fishes are capable of thereby raising their moral status in western psyche.
Metabolic predictors of performance in a changing world (and how they might teach us how we should behave as scientists)
There is currently much debate as to whether fishes are capable of keeping up with the pace of environmental change. Central to these discussions is a renewed appreciation of the among-individual variation in performance, since this variation can be an indicator of the extent of phenotypic plasticity and/or the raw material on which selection can act, driving genetic adaptation. A central question that has been bugging me for the last 90 years or so is: Why does this variation persist, and can we identify its physiological origins?
Given that many behavioural, life history and ecological traits are presumed to be energetically demanding, we might expect some link to metabolism. So does an individual’s metabolic rate predict its performance? The evidence is mixed – there are correlations, but they are often not strong. I will argue that maybe this is not surprising, since we typically measure metabolic rate in terms of oxygen consumption, which is an indirect way to quantify energy turnover. A more direct approach is to focus on the mitochondria. Our recent experiments using brown trout show that the variation among fish in the efficiency with which their mitochondria produce ATP is a predictor of their growth efficiency, but its importance varies according to environmental conditions. In the last part of the talk I will move seamlessly (?) into a discussion of what mitochondria can teach us about the way scientists (should) treat each other. (OK, a bit of a jump, but bear with me…).
Impacts of anthropogenically-altered ecosystems on fish physiology and behavior.
In heavily-altered ecosystems such as those located throughout agriculturally-dominated landscapes, anthropogenic factors have drastically changed available habitats for many native fishes. Additionally, global climate change has resulted in changes to environmental characteristics. As these ecologically-relevant environmental variables have shifted, fish populations have subsequently been in decline, and invasive species have been established in aquatic ecosystems. Stressors such as elevated temperatures, altered flow regimes, shifting food webs, increased contaminant load and reduction of spawning or rearing habitat impact the physiology and behavior of fishes and can lead to long-term population effects. However, animals in nature rarely experience these stressors in isolation, and data evaluating resilience of fish populations to multiple stressors in agricultural landscapes is lacking. Populations already compromised by one anthropogenically-imposed change may be more sensitive to the ecological effects of climate change, and may be unable to adapt as successfully as populations residing in more pristine environments. Furthermore, the need for investigations into the actual mechanisms linking changing environmental variables and fish population declines, including multiple stressor assessments, has been highlighted in the literature over the past decade, and more recently by regulatory agencies. Here, I highlight how the behavior and physiology of fishes may be impacted by anthropogenic activities, with an emphasis on the utility of laboratory studies aimed at understanding the link between aquatic habitat degradation and fish biology, and how this information can be used to develop more effective conservation and management programs.