Advantages of the RAMP approach in vitality-based mortality prediction

Advantages of the RAMP approach in vitality-based mortality prediction were listed by Stoner (2012):

“Despite the limitations of a vitality-based approach to mortality prediction and the current lack of a field validation, the advantages of RAMP in mortality prediction are large. First, a reflex impairment score is based upon presence or absence of whole-animal responses that are independent of animal size, strength, motivation, and gender. This approach avoids the pitfalls of observing physiological variables, which tend to reflect stress in specific body systems, and complex behavioral patterns, which can be altered by factors not related to health, notably by variation in motivation. Consequently, reflex-based indicators appear to be superior predictors of stress outcome compared with either physiological indicators or complex behaviors.

A second important advantage of the RAMP approach is that the index of vitality is based upon a composite of at least four or five reflex actions. Experimental studies with crabs show that different reflex actions are adversely affected by different stressors, but if the RAMP is well designed, the composite score of reflex impairment integrates the collective stresses and injuries to different body systems, providing a robust and universal relationship between reflex impairment and mortality (i.e., the RAMP curve), as previously discussed for Chionoecetes spp. and P. platyceros. A well-designed RAMP assessment will reflect all of the different stressors associated with capture and post-capture exposures along with their likely interactive, cumulative, and synergistic effects (Davis, 2010; Stoner, 2012).

The third primary advantage of the RAMP approach is related to practical application. Reflexes in crustaceans appear to be highly stereotypic, and the abundance of legs and other appendages provides many potential options for testing (Table 5). Stoner (2012) explored more than a dozen reflexes with spot prawn and found that ten were consistent. Most RAMP systems with fishes and crustaceans have employed fewer reflex observations; however, resolution of the mortality predictor will be directly proportional to the number of reflexes in the model. More specifically, percentages or probabilities for mortality can be resolved for each of the different possible scores. Once the reflexes are chosen and established for the RAMP model, they can ordinarily be assessed in hand, and several animals can be assessed per minute without the need for blood sampling, chemical analyses, or tanks of water to observe complex behaviors. The animal can be released quickly with little additional stress caused by the assessment process. Assessments involve little cost, and large numbers of animals can be examined. Most importantly, as pointed out earlier (Stoner, 2009; Benoît et al., 2010; Davis, 2010), a vitality-based approach to mortality prediction does not require holding or tagging the test animals once the mortality predictors have been developed and validated. This allows rapid assessment of any test condition related to different fishing gears, season, different handling operations, and transport, holding, or husbandry conditions."