Reflex impairment in largemouth bass shows interactions of gear type, fight time, and air exposure

Largemouth bass, Bemep/Flicker

Cooke et al. 2016 examined reflex impairment in largemouth bass captured during the summer (25-27^oC). Excerpts from their paper detail study findings: 

“…little is known about how gear strength and fight time interact with air exposure duration to ultimately influence the level of exhaustion experienced by fish at time of release. Here we systematically varied fishing gear strength (ultralight versus medium-heavy) and air exposure duration (0 versus 120 s) when targeting Largemouth Bass Micropterus salmoides. We relied on reflex impairment (using five different reflexes) as a real-time indicator of fish condition.”

“One of the more interesting observations from this study was that fish that were landed rapidly and thus in better condition were more difficult to handle, which led to longer air exposure. We are aware of anglers and scientists that have mused about the trade-offs between fight time and ease of handling, but to our knowledge this is the first study to formally assess this idea.”

“In this study we used two extremes in gear type and suggest that moderate strength gear likely represents the best compromise in terms of achieving an appropriate level of exhaustion that would facilitate handling and hook removal without leading to complete exhaustion.”

Reflex impairment in captured largemouth bass, Cooke et al. 2016.

“Using reflex indicators, we showed clearly that there was a gradient in reflex impairment with Largemouth Bass; fish captured on UL gear had significantly higher reflex impairment than those captured with MH gear with no air exposure, while fish captured with both gear types had similarly high reflex impairment when exposed to the air.”

Stressors, vitality impairment, and survival of fishes

Developing rapid visual in situ trait assessment (reflex actions, injury) associated with vitality impairment.

Video slideshow (2:06) discussing stressors, vitality impairment, and survival of fishes in fisheries contexts.

Reflex impairment and vitality in white sturgeon exposed to simulated capture stressors

White sturgeon, NEEF 2016

A study (McLean et al. 2016) of reflex impairment in white sturgeon exposed to sustained exercise and elevated temperature showed whole-animal stress responses to simulated capture. The RAMP impairment index (a simple proportion of measured reflex actions that were impaired) was used to quantify relationships between treatment times, recovery times, and RAMP score.

The upper figure shows increasing RAMP score with increasing exercise (minutes) in summer (filled circle) and winter (filled triangle) temperatures. The lower figure shows increasing recovery time with increasing RAMP score in summer and winter temperatures. Figures adapted from McLean et al. 2016.

The authors state: “Our study demonstrates that reflex impairment (RAMP) indices are a promising tool to predict post-release vitality in white sturgeon exposed to acute fisheries encounters, such as an angling event. The reflexes used in our RAMP protocol were chosen so that multiple neurological and/or muscle pathways underlying the overall stress response were tested. What we found was that sturgeon exposed to fishing-related stressors had higher RAMP scores and took significantly longer to recover than control fish. The relationship between reflex impairment and stressor intensity (i.e. fishery-related treatment) indicates that sturgeon are undergoing whole-animal (or tertiary) responses to varying degrees of capture stress. Reflex impairment indicators were surprisingly sensitive to fisheries stressors. Control fish had all reflexes intact, whereas multiple reflexes were absent after fish were treated.

It is important to note that it was not the aim of this study to produce accurate mortality estimates for use in C&R fisheries, but rather to explore the use of RAMP on a sturgeon species frequently angled in the wild. We recognize the subjectivity of a whole-animal assessment and categorization; however, given the statistically significant difference in RAMP scores of observationally ‘recovered’ and ‘unrecovered’ sturgeon, we suggest that RAMP is an effective tool for predicting a lowered state of vitality post-release and that this suggests a continuum to an increased risk of delayed mortality.”

Assessment of reflex impairment and mortality in discarded deep-sea giant isopods

Giant isopod, Wikipedia

Giant isopods were subjected to simulated capture and discarding by Talwar et al. (2016). Reflex impairment and mortality were induced by capture, exposure to air, and time at surface before discarding. Reflex actions tested are included in Table 1.

Talwar et al. (2016)

Six reflex actions were tested in control animals. Impairment of antennae extension and pleopod movement were not associated with mortality and were removed from the mortality analysis. Figure 1 shows the relationship between increasing reflex impairment and increasing mortality. 

Talwar et al. (2016)

Note that an impairment score of 0 was associated with 50% mortality. Clearly this score does not mean that animals were not impaired. Stressed animals were initially impaired without associated mortality, as indicated by the loss of antennae extension and pleopod movement.  Removal of these two reflex actions from scoring and the mortality analysis may have produced a tighter analysis, but fails to show the sublethal effects of the experimental stressors. 

Why observe several reflex actions together to measure animal vitality?

Philipchircop 2012

Why observe several reflex actions together to measure animal vitality? The short answer is that animals are whole beings; a summary collection of component parts and their interactions in response to stimuli.

Animals are constructed of biochemical and behavioral components that interact to form a whole; capable of responding to stressors. The interactions of stressors and behavior are also important for prediction of vitality impairment and survival. Reflex actions are fixed behavior patterns that include biochemical, muscle, organ, and nerve functions.

Efforts to identify factors that can control vitality and predict post-release survival and mortality of captured animals generally strive to identify single important variables. For example, temperature changes, injury, exhaustion, and hypoxia can control vitality and survival. For simplicity, single factors are statistically modeled as predictors for survival. Factor interactions are rarely considered because of their complexity.

Patterns of vitality impairment vary with species and contexts. Observing impairment of several reflex actions and possible injury in a defined context integrates the effects of multiple stressors, contexts, and their interactions on animal impairment and survival. Measurement of single reflex action impairment can miss the range of vitality that spans from excellent to moribund. 

Stoner 2012 (crabs)

Below are several examples of the cascading nature of impairment observed as individual reflex actions cease to function in a spectrum of stressor intensities. Reflex actions with higher proportion of impairment are impaired before those with lower percentage. Note that patterns of impairment vary with taxa and context.

Davis 2010 (walleye pollock, coho salmon, northern rock sole, Pacific halibut)

Stoot et al. 2013 (turtles)

Uhlmann et al. 2016 (plaice, sole)

Forrestal 2016 (triggerfish)

Forrestal 2016 (yellowtail snapper)

Danylchuk et al. 2014 (lemon shark)

McArley and Herbert 2014 (snapper)

Sampson et al. 2014 (mottled mojarra)

Stoner 2009 (Tanner crab, snow crab)

Stoner 2012 (spot prawn)

What is RAMP: reflex action mortality predictor?

Reflex actions and injury traits in crab scored for impairment (Stoner 2012, Yochum et al. 2015).

Reflex actions and injury traits in sharks scored for impairment (Danylchuk et al. 2014).

Reflex actions and injury traits in fish scored for impairment (Davis 2010, McArley and Herbert 2014).

Reflex actions and injury traits in turtles scored for impairment (LeDain et al. 2013, Stoot et al. 2013).
Photos; crab - Farm to Market, shark -  Swell Brains, fish - DEEP, turtle - Aquatica.

Any animal has reflex actions and potential injury traits; see diamonds in figures. These fixed traits can be observed, scored present or absent, and summed to form an animal vitality impairment score. Animal vitality is a gestalt of reflex and injury traits that we can observe as a whole animal, active and responding to stimuli. Vitality impairment and mortality are correlated and this relationship is expressed as RAMP, reflex action mortality predictor.

Impairment of well-defined reflex actions and injury types may differ for each species, dependent upon their natural history and phylum.  These species traits of reflex actions and injury types can be scored and combined to express the percentage of whole animal impairment. No impairment represents a healthy animal with all actions present and all injury absent. Increasing absence of reflex actions and presence of injury types is increasing impairment and is correlated with mortality.

Sublethal and lethal zones associated with reflex action impairment scores (RAMP) in walleye pollock, rock sole, sablefish, and Pacific halibut (Davis and Ottmar 2006). For these species at specific transition impairment values, a rapid rise in mortality is observed after a small increase in reflex impairment. 

These curves illustrate the expression “you are alive until you are not”. Animals live in various states of vitality impairment that are correlated with stress. Above a quantifiable level of vitality impairment, animals begin to show mortality, correlated with continued increase for impairment. The distribution of reflex impairment and injury in a group of animals is a measure of population vitality. 

For fish species (Davis 2010, McArley and Herbert 2014), animals have several types of reflex actions which can be secondary or primary. One action group contains secondary peripheral actions that are part of swimming and defensive behavior (fin erection and startle). Impairment of these reflex actions generally indicates sublethal stress effects and is associated with increasing stressor intensity (duration or strength). A second action group contains primary body functions (orientation and coordinated breathing). Impairment of primary body functions generally indicates delayed mortality after stress induction. In the same way, for crustacean species (Stoner 2012, Yochum et al. 2015), loss of leg reflex actions are associated with sublethal stress effects. Loss of eyestalk and mouth actions are associated with delayed mortality after stress induction.

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). 

Elements of vitality testing and delayed mortality in fisheries

Conceptual diagram outlining elements for vitality testing and delayed mortality in fisheries. Fish are captured and environment sampled. Fish become stressed which is measured as impairment from control health by observing reflex actions and injury types. Stressed fish are held for captive observation to determine delayed mortality. Bias and error can be introduced by initial impressions of vitality before testing reflex actions and injury, by differing observer scoring opinions, and by holding conditions that are stressful for the fish. 

Scoring vitality impairment is most difficult when observer decision is used. Training observers is a key part of RAMP development. Reflex actions (RA) are clearly present in control animals, and observers do not need decisions to score present. As impairment increases, scoring RA requires increasing observer decisions about whether sampled RA are present. The decision can be based on how control RA appear to trained observers. Each observer will have different opinions that can be influenced by their initial impressions of the animal and of the stressor treatments the animal has been exposed to.

Initially after stress induction, RA impairment increases and mirrors stress levels, while mortality is not evident. When animals reach a critical impairment level, replicates begin to show mortality, which increases rapidly over small changes in RA score. At highest levels of impairment decisions are less frequent as the animal ceases general movement and responsiveness.

Questions and answers about observer bias in RAMP

Refer to the previous post for background on observer bias in RAMP.

Q: What are the options when grappling with cognitive/expectation and sampling biases in manipulative fisheries research experiments under sometimes challenging conditions at sea?

A: Begin by training and calibrating observation. We all recognize vitality when we see animals with high vitality. This recognition is based on rapid visual assimilation of information about several traits including injury, activity, and responsiveness. We cannot separate our cognitive impression of vitality level from the act of observing individual traits and scoring their presence or absence. Presence or absence of reflex actions is scored relative to control animals which have a set of reflex actions consistently present. Reflex actions range from clearly seen through weakening stages to clearly absent. As the animal becomes more stressed and impairment increases, the interaction of impression and scoring observations contributes bias. 

If observers are trained to clearly recognize a suite of real reflex actions in the species of interest, then correctly recognizing the impairment or absence of those reflex actions should be a realistic accomplishment. An experiment to test for the effect of observer bias and variability in scoring reflex actions could be conducted in the lab or field if enough fish and observers are available. Stress some fish (air exposure) to produce replicates over a range of RAMP impairment scores and have the observers sample reflex actions. Blind the study treatments from observers. Estimates for observer bias from stress studies with different species will be useful for improving observer training by identifying protocols that need to be more defined and less subject to observer opinions. Alternatively, Benoît et al. (2010) modeled observer bias as a random factor. 

Q: How can we achieve a blinded experimental design if the experimenter who assigns or is aware of experimental treatments also scores reflex impairment on board (commercial) vessels?

A: Perform some fish experiments on observer bias outlined above and decide how important observer bias is after training with well-defined protocols for testing individual reflex actions. The bias problem may be mitigated by training using clear definitions of present or absent for reflex actions. I will assume that the vessel captain is conducting the experimental fishing treatments. So the captain could be given treatment conditions by the scientist and then could conduct fishing by assigning treatments randomly without the knowledge of the scientist observer. However tow time, soak time, or haul time and catch volume will be apparent to observers. 

Q: Is an observer influenced in his/her ability to score reflexes if, apart from knowing the treatment, also the condition of an organism is evident even before the scoring begins? Is there any option to minimise this?

A: We cannot separate the correlation between overall impression of vitality and scoring reflex actions. However, we can be trained to clearly recognize the presence of reflex actions. Any impairment through weakness, delay, or loss of action is scored absent.  The key method for minimizing observer bias for reflex actions is to clearly establish what the suite of reflex actions look like when they are consistently present in control animals. If presence of a reflex action is difficult or inconsistent to determine then it is not a good candidate for testing. Any deviation from control appearance in action strength or delayed time for action can be considered impaired and scored absent. The goal is to eliminate variability in detection of presence for reflex actions. By sharpening the decision criteria, bias and variability can be reduced. This idea can be tested using the outlined experiment design.

Q: Seeing that vitality assessments of discarded fish in Europe are now being developed in several places is there a need to also quantitatively evaluate the ability of different observers to score reflexes consistently? What would be the best setup for such a training exercise? 

A: As mentioned above, a stress experiment can be conducted to quantify observer bias and consistency.  With enough replicate fish and observers, an air stress experiment could produce fish with varying levels of reflex action impairment. These fish could be sampled by observers with defined criteria and using an experimental design for testing the effects of observer variability and bias. The effect of training could also be evaluated using this design.

RAMP is a component of an integrated conservation approach to coho salmon bycatch mortality management

Raby et al. 2014

Results of Raby et al. 2014 demonstrate the integration of vitality impairment and coho bycatch mortality estimation and management.

“We have provided an estimate of bycatch mortality for an endangered population of coho salmon captured in an aboriginal beach seine fishery, based on three years of tracking fish released from the fishery.” 

“Among all the variables we tested as predictors of mortality, none were significant except for RAMP score, whereby fish with higher RAMP scores (more impaired) were less likely to be successful migrants (Table 3, Fig. 4).”

Distinguishing between natural mortality and bycatch mortality. 

“An alternate approach to calculating a bycatch mortality rate that attempts to distinguish bycatch from natural mortality, is to use RAMP scores and their mortality rates at each level of impairment, and assume negligible bycatch mortality for the fish that were least impacted (vigorous at release).”

“Since some in-river mortality is natural, there is a need to attempt to differentiate mortality caused by the capture itself. To do so, RAMP scores can be used whereby coho salmon released with little or no reflex impairment (vigorous) are assumed to experience no post-release bycatch mortality. Using that conservative assumption, the post-release mortality rate for those fish can then be used as a baseline within the data set. Additional mortality above that baseline that occurs at higher levels of reflex impairment can then be assigned to the fishery (see Fig. 4).”

Using RAMP to monitor condition of bycatch and improve their survival

“The expanded validation of the RAMP approach in the present study provides confirmation that this simple technique is ready for use in this fishery if needed (Raby et al. 2012). The observers in the fishery could easily be taught how to conduct RAMP assessments to monitor the condition of bycatch in real time, provide advice to their crews on how to improve fish condition, and make decisions about whether individual fish should be revived using recovery bags.”

Making and Using RAMP in Fisheries

A video is available that explains making and using RAMP in fisheries.

Why is vitality impairment related to mortality?

By definition, healthy animals have full vitality. Vitality becomes impaired as animals become stressed by capture and handling. Severe vitality impairment can result from the effects of physical injury or other stressors, e.g., fatigue, temperature, light, sea state, and air exposure. Maladaptive stress responses or critical injury associated with severe vitality impairment can result in immediate and delayed mortality.

Why score reflex actions and injury?

Reflex actions are fixed behavior patterns that are directly related to vitality impairment, without control by volitional behavior factors, e.g., motivation, hunger, fear, shelter seeking, migration, and reproduction. Reflex actions reflect the state of neural, muscle, and organ functions.

Injuries are directly related to vitality impairment because they can control neural, muscle, and organ functions.

Scoring vitality impairment in general

Any type of reflex action or injury that is related to vitality can be summed to score vitality impairment. The important point is that a sum of presence/ absence scores for vitality characteristics produces an index of vitality impairment. This vitality index can then be used as a measure of variability for sublethal stressor effects in fisheries, as well as a validated indicator and predictor of mortality and survival.

Steps for making and using RAMP in fisheries.

Ecological significance of cold shock: reflex action impairment in bonefish

Bonefish, Florida Sportsman

Fast moving weather fronts or upwelling events can rapidly drop water temperature in sub-tropical areas. Effects of cold shock were studied in bonefish by Szekeres et al. 2014. Fish at 25^oC were exposed to either 18^oC or 11^oC for 2 hours. Ventilation rate and reflex actions were monitored throughout the cold shock. Five reflex actions were tested before and after cold shock, including equilibrium, body flex, vestibular-ocular response, tail grab, and head complex (Brownscombe et al. 2013). Given that the focus of this study was on sub-lethal effects, cold shock exposure was terminated if the fish lost equilibrium. Blood plasma and swimming ability, defined as line crossings and time to loss of equilibrium associated with chasing were also sampled during the experiments.

The authors found that “Behavioral responses of bonefish to cold shock were generally characterized by decreased ventilation rates for the 7°C below ambient treatment with little reflex impairment, and extreme behavioral and reflex impairment in the 14°C below ambient treatment. Fish in the latter treatment exhibited varying periods of hyperactivity followed by impaired or no swimming ability, reduced responsiveness, and the loss of equilibrium, which are all common traits of cold shock exposures.” Experiments with bonefish exposed to the 14°C below ambient temperature were terminated after 30 minutes, as fish lost equilibrium.

Importantly, the authors found “Despite the fact that bonefish in the 14°C below ambient treatment had almost complete reflex impairment during the exposure and sustained high blood lactate concentrations than other treatments, post-exposure swimming abilities were similar to handled control fish. This suggests that although fish become highly behaviorally impaired at colder temperatures, if they are able to escape to more suitable conditions, swimming abilities quickly return and they are unlikely to experience further fitness consequences due to behavioral impairment (e.g. higher predation risk).” 

There “are many facets that have yet to be explored as this research was the first attempt to understand the sub-lethal consequences of cold shock on these sub-tropical fish species. Our research only considered swimming ability as a proxy to understand predation risk in the wild. Future research may focus on determining whether the fish experience compromised disease resistance, poor foraging decisions, changes to fecundity or altered developmental stages. The combination of a changing climate and the economic importance of bonefish throughout the Caribbean warrant more research to be conducted on this species and their responses to an array of changes to ambient conditions.”

Methods for estimating discard survival in fisheries: an integrated approach

Discarding Pacific halibut, FAO

ICES has published a report on methods for estimating discard survival in fisheries. The report details the results of the February, 2014 ICES WKMEDS workshop on discard survival.

“This report will:

-  describe the concepts behind assessing discard survival (Sections 2 and 3);

-  describe three different approaches for estimating survival (vitality assessment, captive observation and tagging) (Sections 4, 5 and 6); and 

-  provide guidance on the selection of the most appropriate approaches and experimental designs, as well as how to integrate and utilize information from them, with respect to specific discard survival objectives (Sections 3, 7, 8 and 9). 

Later versions of this report will cover in more detail: 

-  techniques for assessing survival using tagging and biotelemetry; and 

-  the most appropriate methods for analyzing and reporting survival data. 

It is assumed that the user of these guidance notes has sufficient scientific training, or at least access to suitable scientific support, to be able to conduct the techniques described in these notes in an appropriately systematic and disciplined manner. However, these guidance notes are intended also to be informative for other stakeholders associated with fishing (primarily fishers and managers) who wish to support and understand discard survival estimates.”

The ICES WKMEDS report is a summary of an integrated approach for estimating discard survival. The approach uses various combinations of vitality assessment, captive observation, and tagging to achieve realistic estimates for discard survival in fisheries. The combinations of methods are determined by scientists, stakeholders, and managers using evaluation and prioritization:

“the choice of which species in which fisheries to study depends upon several criteria: existing survival information, the biological traits of the species, its population status, magnitude of discarding, fishery characteristics, environmental characteristics, socio-economic value of the fishery, available resources, and management policy. The process of prioritizing is unlikely to be simple and may involve a number of iterations, where results of preliminary studies inform the final choice.”

The ICES WKMEDS report represents a new approach for estimating discard survival. Sources of information about objectives, priorities, resource implications, and time frames are included in a decision matrix. Managers can use the matrix to make informed choices about discarding in key fisheries and management units and what methods can be used for further study of discard survival. Initial calibration of vitality assessment using delayed mortality observations of discards creates validated indicators for survival. Then use of validated vitality assessment indicators such as RAMP (Reflex Action Mortality Predictors) can provide rapid real-time assessment of potential discard mortality on-board fishing vessels.

ICES. 2014. Report of the Workshop on Methods for Estimating Discard Survival (WKMEDS), 17–21 February 2014, ICES HQ, Copenhagen, Denmark. ICES CM 2014/ACOM:51. 114 pp.

The importance of vitality in fishing experiments

Key fishing stressor factors, Davis, 2002

Knowledge of key factors controlling fisheries is necessary for sustainable management of fishery stocks. Scientific hypothesis testing in the form of fishing experiments is a necessary component of fisheries knowledge development and validation. Fishing experiments are performed in the field by simulating actual fishing conditions, by actual fishing, and during survey cruises. Fishing experiments can be used to identify key stressor factors that control and contribute to the survival and mortality of captured, discarded, or escaped animals as well as identifying the key factors controlling fishing gear capture efficiency and selectivity.

Trawl captured animals, Robert A. Pawlowski, NOAA Corps

While field fishing experiments represent realistic conditions, they are a matrix of confounded factors which cannot be easily separated into mechanistic hypothesis tests and explanations of factor importance. Effects of factors are often synergistic and prior animal stressor history can alter relative effects of subsequent exposure to factors, e.g., depth changes, injury, elevated temperature, air exposure, and size and species differences.

Flow chart of experimental fishing stressor factors, Davis and Olla 2001

Simulated fishing experiments with factors in controlled laboratory conditions is one way to test hypotheses about mechanistic effects of individual factors and their interactions. However these laboratory experiments are generally viewed as not realistic to field conditions and they are used to identify factors that may be important in the field. Furthermore, modern requirements of animal care laws and committees restrict the use of laboratory fishing experiments by not allowing human application of experimental stressor factors on animals and the use of mortality outcomes. These same laws and committees do not have jurisdiction over field fishing experiments. 

Laboratory trawl tow tank, NOAA RACE

Given that factors are confounded in field fishing experiments, how can we test for effects of factors in the traditional mechanistic hypothesis test? We can test for changes in animal vitality. Since vitality has been shown to be correlated with survival and mortality, it is a useful indicator of animal outcomes before and after exposure to experimental stressor factors. For example, we generally do not know the exposure of animals to stressors prior to experimental manipulation of factors. Not knowing the complete stressor profile is not an obstacle since the animal knows the complete stressor profile and presents vitality levels that have integrated the effects of that profile. Then we can expose animals to additional stressor factors and measure further changes in vitality from their initial levels. 

Important to shift mechanistic thinking from needing to know the effects of individual factors to knowing the effects of fishing variability. Manipulations of time in air and elevated temperature represent differences in fisher sorting and handling behavior on deck and are appropriate for defining the effects of fishing variability. Effects of variation in tow time and catch quantity can be manipulated and are included in the mix of animals landed. The questions of associations among individual fishing stressor factors is left for another day and are more of interest to mechanistic scientists than to managers and fishers. Fishing variability will give a picture of the fishery and its potential effects on animal vitality. By measuring animal vitality, which integrates the effects of stressor factors, you have measured a key master variable that indicates the important effects of fishing.

Vitality is the key variable that can be used to indicate and predict delayed survival and mortality outcomes for discards and escapees from fishing. The relationships between vitality and survival and mortality are defined by captive observation or tagging and biotelemetry experiments. During exposure of animals it is important to insure that all stressor types normally in the fishery in question are present for the population of tested animals (e.g., temperature, air exposure, fatigue, injury) and that a full range (0-100%) of vitality impairment and mortality are observed. Then relationships can be calculated for each species of interest that do not extrapolate beyond available data ranges and that apply to the fishery of interest. These relationships can then be used to predict survival and mortality for animals under any condition of interest in the fishery without the need for further captive observations or tagging.

Consider how scientific peer-reviewers may see this shift from mechanistic thinking and develop thoughts that elaborate the importance of vitality from the animal’s point of view. Some resistance is expected from mechanists who believe that they can attribute cause and effect to individual factors. There is always a matrix of interactions, even under the most restrictive and controlled experimental conditions. There are always interactions and synergisms to account for. As a result, there are associations among factors, rather than cause and effect. In other words, there are causes and conditions associated with effects. 

From the fishing experiment perspective, we set up fishing conditions that are real or that simulate fishing and then measure animal vitality, which is an integrated measure of the effects of interacting factors. It is useful to identify the important stressors by experimentally changing them in fishing experiments; changes in time in air, trawl time, trap retrieval time, depth, season, temperature, catch amount, and injuries. Always remember that there is a hidden context of conditions, i.e., the animals are prestressed by other factors not being controlled. But this hidden context can be accounted for by observing and comparing vitality impairment among animals observed in all treatments, including simply captured animals without additional stressor exposures (using positive controls). This experimental approach is useful both for fishers who wish to modify fishing gear and practices, as well as managers who wish to observe animal vitality and correlate that with mortality and survival.

Allostasis and it's correlate vitality; measured with reflex action impairment and injury

Figure 1. Alternative models of regulation. Homeostasis describes mechanisms that hold constant a controlled variable by sensing its deviation from a “setpoint” and feeding back to correct the error. Allostasis describes mechanisms that change the controlled variable by predicting what level will be needed and then overriding local feedback to meet anticipated demand, Sterling (2003).

Physiological regulation is considered the cornerstone of animal survival and avoidance of death. Inability to regulate is indicated by vitality impairment and causes an animal to exceed its capacity for life. To understand and predict the causes for survival and death, we must be able to measure appropriate state and rate variables involved in regulation. The generally accepted model of physiological regulation is homeostasis, based on the concept of stability through constancy. However homeostasis is unable to explain accumulating medical evidence that physiological variables do not remain constant. Clearly a more comprehensive model of physiological regulation is needed.  

Allostasis is a model of physiological regulation based on the concept of stability through change (Sterling 2003). Allostasis is able to account for evidence that physiological variables are not constant. The allostasis model connects easily with modern concepts in sensory physiology, neural computation, and optimal design, to produce anticipatory regulation. Allostasis was developed with the recognition that the goal of regulation is not constancy, but rather fitness under natural selection, that implies preventing errors and minimizing costs. Both needs are best accomplished by using prior information to predict physiological demand and then adjusting all variables to meet it. In allostasis an unusual variable value is not a failure to maintain a setpoint, but is a response to some prediction made through perception or prior knowledge. Constancy is not a fundamental condition for life. A mean value need not imply a setpoint but rather the most frequent demand.

The brain has close access to essentially every somatic cell through nerve cell connections. The broad metabolic patterns over short and long time scales, and under mild as well as emergency conditions are controlled by the brain. In other words, the brain regulates both physiology and its supporting behavior (Sterling 2003). The use of reflex action impairment to measure vitality and predict survival and mortality is consistent with the allostatic model because it is representative of key elements of physiological regulation; including perception, behavior, and neural control of somatic cell function. Injury also measures vitality impairment because of its direct effects on neural and somatic cell function, hence allostasis. 

Reflex action impairment and injury can measure vitality and predict survival and mortality in taxa ranging from invertebrates to humans. Clearly the presence of higher brain function is not a necessary condition for the allostatic model. Instead, simple interactions of neural and somatic cells can produce allostasis regulation and its correlate, vitality. It remains to elucidate the comparative details of physiological regulation as it developed in new phyla through evolutionary time.

When studying the causes for death, shifting focus from measurement of lower level plasma variables (cortisol, lactate, glucose, O2, pH) to higher level variables (vitality in its various guises) would advance the assessment of physiological regulation and its role in survival and death. Particular values for plasma variables are of secondary importance, until reaching outer limits of operation. The interactions of plasma variables are of primary importance (Ellis and Del Giudice 2014). The homeostatic model fails to capture the importance of stability through change; how animals adapt and ultimately go beyond their physiological limits. The allostatic model addresses stability through change and invites adaption and evolutionary fitness.

Reflex action impairment is probably a biomarker for impairment of physiological regulation and this is why the RAMP curve is non-linear, reflecting the inflection point where physiological regulation is lost and death results. Addition of injury to RAMP adds details of direct injury effects on physiological functioning and regulation, e.g. compromising integument gatekeeping (skin, gut, gill, lung).

Measuring reflex action impairment in sole and plaice; preliminary steps to making RAMP

Collection of fish with beam trawl, Jochen Depestele

The beginning steps for measuring reflex action impairment and making a RAMP are detailed in “Calibration tests for identifying reflex action mortality predictor reflexes for sole (Solea solea) and plaice (Pleuronectes platessa): preliminary results” authored by Depestele, J. et al. 2014. Experiments were designed to collect sole and plaice using short hauls of a beam trawl, to test their reflex actions, and to identify consistent reflexes for making RAMP. These experiments followed steps for making RAMP.

A short video demonstrates testing plaice for reflex actions including righting, eye roll (vestibular-ocular response), evade, operculum, mouth, and tail grab. Fish are shown in a series of increasing impairment.

Conclusions from the study included:

Preliminary investigations have been undertaken on-board the RV Belgica to assess the potential presence of a range of reflexes in sole and plaice. A wide range of potential reflexes was investigated prior and during the sea trial, leading to a final selection of seven reflexes with a good potential of being consistently present in fish in a favorably vital condition. Fish in a “perfect” condition could not be retrieved, but 22 individuals of plaice and sole were selected from short hauls and their survival potential was evaluated during 70 hours in on-board holding facilities. Only one sole died, and indicated hence that the control fish for the calibration test serve purpose.

Holding tanks for fish on board RV Belgica, Jochen Depestele

The final selected reflex actions were very similar for sole and plaice, except for one. Forced opening of sole’s operculum did not reveal much resistance of the fish, while holding plaice by its head did not induce curling of the fish. The most consistent reflex actions for sole were called “stabilize, mouth, and tail grab”, followed by the “vestibular-ocular response”. Vital individuals seemingly dig into the sand or stabilize themselves onto the floor of the water-filled box. They also keep their mouth closed when trying to open it with a probe. When fish have stabilized, they respond clearly to grabbing their tail or even tickling it. The “head” reflex was easy to assess, though not always present. However, it is clear that vital soles curled around one’s hand when they had been in holding tanks. This was not that obvious for fish that were just released from the codend. Natural righting was observed regularly, although some individuals remained at their backs for >5 sec and did not return to their natural position at all or only after stimulating them. The consistency could thus be questioned, but good candidate reflexes were proposed for sole, and should be further evaluated. The most consistent reflexes of plaice were the turning of the eyes when the fish was turned around longitudinally. The resistance of plaice to forced opening of the operculum was a clear reaction as well. Not fully consistent, but nevertheless a good indication of the reflexes was the “evade” response and the “tail grab”. When the tail is touched or grabbed in a “good” way (which might require some practice), then the fish swim away, or at least the fins stimulate propulsion. The mouth of plaice was easily opened, but mostly the individuals tried to close it or seemingly opposed to the forced movement.

Our investigations confirmed that on-board holding facilities result in high survival of plaice and sole from very short hauls (<20min). Investigated individuals were non-randomly selected and thus it was not surprising that their physical injuries were limited. These individuals were suitable for developing the reflexes, although they were limited in number (22 for plaice and 22 for sole) and they also did not range over a wide variety of fish conditions (e.g. limited length variability). The seven reflexes from these preliminary investigations are therefore proposed as candidates for the development of a RAMP score for sole and plaice.

The tests of the reflexes were run directly after releasing fish from the codend. When examining the survival from fish that were accommodated for some time (e.g. 48 hours), we noted that they reacted more strongly and had much clearer responses to the reflex tests. In particular the tail grab worked very nicely for sole when their status (alive or dead) was tested. Therefore we suggest that the proposed reflexes are tested once more on surviving individuals of short hauls after an accommodation period of >24hours. Consistency of the outcome of the reflex tests is expected to be improved when the impairment from the catching process is accounting for. Other recommendations for follow-up tests relate to the registration of potential environmental and biological confounding factors.