Observing vitality impairment

Animal vitality can be measured by observing species traits associated with activity, responsiveness, and injury. For each species, a group of reflex actions can be observed that are consistently present in healthy animals. As vitality becomes impaired, reflex action traits disappear and injury traits may begin to appear. 

Activity, responsiveness, and injury for measurement of vitality impairment (Benoît et al. 2010). 

Fisheries show gradients of stressors associated with capture, handling, and release or escape. Discard mortality, survival, and vitality impairment are controlled by stressor gradients.

Gradients of mortality and simulated stressors in sablefish fisheries; water temperature and gear type including trawl (time), longline, pot. Smaller fish are more sensitive to stressors (AFSC).

Vitality impairment gradients are associated with stressors and can be used to predict survival and delayed mortality for populations of impaired animals. Vitality impairment gradients can be measured by identifying classes of health condition; excellent, good, poor, and moribund based on rapid observation and impression of animal injury and activity (Benoît et al. 2015). 

The resolution for observations of vitality impairment gradients can be increased by including more information. RAMP is an example of this approach (Davis and Ottmar 2006, Davis 2010). A list can be made of reflex actions present in control animals and possible injuries. Then presence or absence of listed traits is observed after exposure to stressors. Increasing impairment is associated with stress effects and morbidity.

Reflex actions observed in snapper by McArley and Herbert 2014.

Relationships between vitality impairment and survival or delayed mortality can be experimentally determined. Then predictions of stress effects in other settings with similar stressors can be made by measuring vitality impairment associated with stressors, without the need to hold or tag animals. Vitality impairment can be rapidly observed in sampled populations as an additional factor to evaluate stressor effects and is a useful indicator of animal health and stress status, that can be validated experimentally.

Reflex impairment and mortality for individuals (A) and groups (B) of Atlantic cod with 95% confidence intervals (Humborstad et al. 2009).