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.”

Yelloweye rockfish barotrauma and reflex impairment after capture in shallow and deep water

Yelloweye rockfish, Neil McDaniel

Rankin et al. 2016 report on barotrauma and reflex impairment observed for recompressed yelloweye rockfish in situ. They evaluated orientation, reaction to noise and motion stimuli, and visual and swimming capability. 

Behavior of recompressed fish. Top fish, presence of orientation and vision-dependent movement. Bottom fish, absence of vertical orientation in live fish. Rankin et al. 2016

The authors conclude, “Recompression is a valuable treatment for discarded rockfish that would otherwise be too buoyant to return to depth without assistance. However, the loss of reflex actions as basic as vertical orientation, along with the evidence we found of visual compromise in deep-dwelling recompressed yelloweye rockfish, is concerning, as are the long-lasting physical injuries and lack of neutral buoyancy observed in the weeks after capture and recompression. At a minimum, these effects indicate limits to a rockfish’s ability to move effectively, find refuge, and avoid predators upon release.

The findings from these two studies, which reveal severe and lasting injuries, as well as behavioral compromise of recompressed deep-water yelloweye rockfish, reinforce the importance of avoiding fishing contact with deep-dwelling yelloweye rockfish and maintaining spatially-managed rockfish conservation areas closed to fishing.”

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.

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)

Using vitality scores to predict post-release survival of plaice

European plaice (Picton & Morrow, 2015)

A recent study of plaice after capture and release from a beam trawl determined that vitality scoring can be used to predict post-release survival (Uhlmann et al. 2016). Vitality scores included observation of reflex impairment and injury. 

Figure from Uhlmann et al. 2016.

The authors conclude: "Our results illustrate that a vitality score and TL were the most relevant explanatory variables to predict post-release survival probability of plaice. In agreement with other post-release survival studies (Yochum et al., 2015), 14 d of post-release monitoring was appropriate to capture almost all fishing-related mortality events. Although one fish died after 21 d, > 60% of mortalities occurred within the first 4 d. Reflexes of both plaice and sole were sensitive to capture stress, in particular air exposure, although some of the differences may have been related to an observer effect."

The authors noted reservations about scoring vitality: "As with other animal behaviour scores, reducing a continuous spectrum of responses to presence/absence observations to improve practicality (Cooke et al., 2013) require a well-defined protocol, and assessments of bias, especially when multiple observers are involved (i.e. inter-observer reliability, Tuyttens et al., 2014). Although scoring binary as opposed to ordinal or continuous responses removes some subjectivity in interpretation (Tuyttens et al., 2009), it may still persist by abstracting from a continuous scale (Tuyttens et al., 2014)."

Uhlmann et al. (2016) comments about binary scoring expose a misconception about vitality scoring using the RAMP approach. For RAMP, presence or absence of individual reflex actions and injuries are given a binary score and then summed to derive an ordinal or continuous vitality score, representing the sum total of impairment. The vitality score is then correlated with survival or mortality for samples of animals (Davis 2010, Stoner 2012).

Future research is suggested to refine the vitality method: "Further research is needed to disentangle the effects of observer, and expectation bias on reflex impairment scores, especially in studies where more than one scorer is involved. Accuracy of scores may also be improved, if researcher handling periods before reflex (and injury) assessments are kept consistently as short as possible. Finally, the utility of RAMP as a proxy to predict post-release survival will depend on both laboratory-based and field calibration studies where key technical, environmental, and biological drivers of post-release survival are included." 

Importance of context for RAMP curves used to predict mortality and survival of stressed animals

Relationships between reflex/buoyancy impairment and post-capture mortality for Atlantic cod (Humborstad et al. 2016).

Humborstad et al. (2016) looked at the relationship between reflex/buoyancy impairment and post-capture mortality for Atlantic cod exposed to fishing stressors. RAMP curves were generated for (a) fish exposed to laboratory simulated forced swimming, air exposure, and net abrasion, (b) field longline capture, and (c) field pot capture. The authors concluded that:

“It appears that specific RAMP curves may be needed for gears that involve different stressors, including consideration of any additional stress associated with captive observation of delayed mortality. Differences in stressors and holding conditions certainly reduce the general applicability of RAMP across different stressors and fisheries. However, once a RAMP curve has been established for a specific set of stressors or gears, the strong relationship between reflex impairment and mortality shows the potential for predicting mortality outcomes, especially at high and low levels of impairment.”

“Reflex impairment could predict mortality among fish caught by pot and longline. However, different RAMP curves were observed between laboratory and field conditions, indicating that careful consideration must be given to the types of stressors present and captive-observation conditions for delayed mortality when comparing RAMP curves for different fisheries. The inclusion of buoyancy status in modelling greatly improved mortality predictability.”

Science and medicine generally do not know proximate and ultimate causes for why fish and other animals die. This lack of mechanistic knowledge precludes us from direct understanding and prediction of death. However, we can observe correlates with death; animal size, stressors, vitality impairment, and physiological impairment. These correlates can be used to identify risk factors and predict immediate and delayed mortality. 

Successful mortality and survival prediction requires that the context of animal exposure to stressor risk and recovery be included in any experimental analysis of this problem.  We cannot simply identify stressors, impairment, or physiological numbers and say that they will result in a particular mortality (Davis 2002). RAMP curves clearly show the importance of context for exposure to stressors and potential mortality or survival (Davis 2010). The question of interactions among stressors and their context has recently been elaborated for freshwater and marine systems (Jackson et al. in press).

Triage for captured and released fisheries species: research and survival

Will they survive? (The Guardian, 2013)

Vitality impairment can be linked to post-capture mortality in fisheries bycatch. Vitality impairment can be estimated by direct observation of animal activity, responsiveness, and injury. For each critical fisheries species in crabs, fishes, sharks, and turtles, reflex actions that are consistently present in healthy, uninjured individuals are listed as control levels. Impairment is signified by loss of reflex action types and addition of injury types after capture.  

Reflex actions are fixed, consistent animal behavior patterns that can be triggered by perception of external stimuli (light, sound, smell, gravity, touch). Stimulation of reflex actions is not controlled by body size, motivation, strength of stimulus, or fear. Reflex action traits summed as a whole animal can be an expression of vitality (Davis 2010). In contrast, volitional behavior can be altered by body size, motivation, strength of stimulus, fear, cognition, and as such is not a controlled measure of vitality.

With the species reflexes and potential injury lists, observations of captured animals can be made in commercial and sport fisheries. Patterns of significant impairment can be determined and related to fishing context and species (Raby et al. 2015). These patterns help identify the relative effects of fishing gears, handling, and physical factors (air, temperature, light, pressure) on impairment and potential survival and mortality.

Figure shows overlap between information on animal physiology and fisheries biology, adapted from Horodysky et al. 2015 and modified to show vitality information. Measures of vitality include reflex impairment and injury, which are whole animal measures that are ecologically relevant, linking physiological and population level research and hypothesis testing. Volitional behavior is coordinated whole animal movements beginning with perception and motivation, followed by attraction and aversion to various stimuli (injury, threat, food, shelter, species mates, migration).

Patterns of vitality impairment can guide research questions and priorities to triage fisheries for treatment of bycatch mortality and enhancement of survival. Vitality impairment can measure the efficacy of engineering fishing gears to increase bycatch survival. 

RAMP method video developed by ILVO

ILVO (Belgium Institute for Agricultural and Fisheries Research) has developed RAMP methods for three species of flatfish (plaice, sole, and dab) in European fisheries.

The first video sets the scene and explains the potential relevance of this method in relation to the recently reformed European Common Fisheries Policy.

The second video explains and demonstrates reflex tests in more detail and may guide other investigators in defining and recognizing reflex actions.

An excerpt from the video text explains, “A staggering amount of commercially-caught fish is being thrown overboard. Some say that all of those discarded fish are either dead before they hit the water or they die soon after, victims of predation or injury. But others argue that some of those species are strong enough to survive after being discarded and live long enough to reproduce. The European Common Fisheries Policy was recently reformed and will now phase in a ban on discarding, meaning that fishers will have to land everything they catch. The idea behind the ban is to stimulate more selective fishing techniques, because it will be in the fisher’s interest to only catch the most valuable fish. However, by landing everything, this ban risks killing more fish than before. If a juvenile fish lives long enough after being discarded to spawn new fish, it should be given that opportunity. For this reason, the discard policy provides an important exception: if a certain species can be scientifically proven to have a high chance of survival, fish of that species should be thrown back after catch. Researchers at the Institute for Agricultural and Fisheries Research (or ILVO) in Ostend, Belgium are testing the most commercially important species of flatfish - plaice, sole and dab – for their likelihood of survival.”

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.

Belly up: Righting reflex action time to recovery correlated with delayed mortality?

Upside down fish in market tank (Hong Kong)

RAMP incorporates presence/absence of several reflex actions and injuries to measure vitality impairment and potential delayed mortality. A simpler method may be possible by measuring time for recovery of orientation when fish are placed upside down in water. This method can be tested.

Place a fish upside down in water and observe the time until the fish returns to normal orientation. This duration is a measure of vitality impairment. Longer recovery times indicate greater vitality impairment and data can be included in statistical models for relationships among fishery stressors, injury, righting time, and delayed mortality. We can test the relationship between righting impairment and delayed mortality. 

Righting reflex action is a central behavior that is the nexus of neural, muscle, and organ actions and is intimately linked with loss of physiological regulation associated with stressor exposure.  Olfactory impairment is another example of a central function that is correlated with delayed mortality (in humans, Pinto 2014).

Body orientation is a sensitive measure of fish consciousness. Presence or absence of righting can be included in the RAMP score. Loss and recovery of orientation is a well known symptom for induction of and recovery from fish anesthesia and is used as an indicator of morbidity and delayed mortality in stress experiments (Davis and Ottmar 2006, Szekeres et al. 2014, Raby et al. 2015).  

Measuring replicate animals for the time to righting recovery and delayed mortality after a stressor experiment can test the correlation between righting impairment and delayed mortality. If the correlation between righting and delayed mortality is valid and strong, then we have a rapid method for predicting discard mortality on board fishing vessels without need for holding or tagging fish to confirm their survival. Research groups on fishing vessels can observe fish during catching, landing, sorting, and discarding under differing stressors; seasons, water temperatures, tow durations, catch quantities, species mixes, and sorting times.

Measuring and scoring vitality impairment

Associations between vitality impairment and mortality in Tanner and snow crab; Stoner et al. 2008.

At the risk of repetition and irrelevance, I will repeat my short history with vitality impairment and mortality.  I began by trying to find out what kills fish. The word fish applies to all animal types in a fishery. We chose to do this in the lab for control reasons, given the common confounding of stressors in fisheries (Davis 2002). All sorts of objections were made by field people that the work was irrelevant because it did not include field conditions. Well we focused on the fish and their capabilities, in an effort to formulate hypotheses that could be tested in the field. We found that each species and size of fish has different sensitivities to stressors and that stressors of importance were different for species.  We also found that some stressors (temperature and hypoxia) could kill fish without apparent macro-injury. After killing many fish, we endeavored to identify characteristics (traits) of fish and fisheries that could be correlated with mortality as predictors, given the difficulty of holding fish and measuring delayed mortality in the field. We tried many traits; muscle and plasma physiology, stressors, volitional behavior, injury, and reflex actions.

Effects of fishing gear, temperature, and fish size on sablefish mortality, NOAA.

Muscle and plasma physiology were not correlated with mortality because these are alarm responses that can be adaptive or maladaptive responses to stressors. In specific contexts, lactate and CO2 may be useful where hypoxia or fatigue are a concern.  

Stressors are an approach that has garnered enthusiasm. However their effects can be confounded and difficult to model given the relatively unlimited combinations of factors that are possible in a fishery; seasonal effects, gear type and deployment times, catch type and amount, sorting and discarding.  

Volitional behavior is not correlated with mortality because it is subject to variation that is not directly linked to mortality, such as changes in perception, motivation, fear, and attraction; all which confound the relationship of behavior and mortality.  

Injury is often correlated with mortality, especially in accidental death.  However not all mortality is correlated with injury, as in the effects of temperature and hypoxia, for which micro-injury may be evident (apoptosis) but difficult to measure in the field. Often the effects of injury, temperature, and hypoxia are confounded making interpretations of their effects on mortality difficult.

Single reflex actions are often not correlated with mortality when they are part of systems not central to body function and regulation directly related to mortality. They may be important for complex behaviors; predator avoidance, feeding, habitat choice, migration and these can have indirect effects on mortality. 

We reasoned that fish had a quality called vitality and that vitality was correlated with mortality. However, for an individual fish this relationship is binomial. The fish is alive or dead. So decreasing vitality results in sublethal effects on behavior until a threshold is reached and the probability for death increases rapidly. In statistical groups of fish, decreasing vitality is log-linearly related to mortality.

At this point we chose to not measure the strength of reflex actions (because of confounded size effects); instead to score the presence or absence of several reflex actions as an expression of reflex action impairment and loss of vitality. Reflex actions are fixed behavior patterns based on neural, muscle, and organ functions which do not vary with changes in perception, motivation, fear, and attraction.  We chose to focus on several types of reflex actions to increase the probability that reflex actions key to body regulation were included. Later work has shown that the orientation reflex is such a key reflex, often correlated with morbidity and mortality associated with hypoxia and fatigue. 

Previous work with vitality scoring in fisheries had developed the semi-quantitative analysis method (SQA) of scoring fish activity and injury, which was used in tagging studies and in Pacific halibut discard mortality estimation (ICES 2014). The method observes the sequential loss of operculum clamping and startle to touch and increased injuries from minor to major and bleeding; with ordinal scoring (1-4) for severity of impairment. The vitality score is readily incorporated in multivariate models that may identify stressors of importance to mortality and model mortality based on those stressors. RAMP can be scored in a similar manner as SQA and included in multivariate models. RAMP scores severity of impairment by noting the sequential loss of several types of reflex action and inclusion of injury types. Scores range from 0 to a maximum which is the number of trait types observed for presence/absence. Strength of action and extent of injury are not included because of the confounding effects of size. The effect of size is included in the model explicitly as fish length or weight. Smaller fish will have more vitality impairment than larger fish, when exposed to equivalent stressors.

RAMP is a simple extension of the SQA concept that includes more testing for reflex actions. SQA and RAMP are similar scoring systems that differ by emphasis. SQA and RAMP score activity, responsiveness, and injury to quantify levels of vitality impairment. RAMP simply includes more information about types of reflex actions in an effort to include reflex actions that are central to body regulation over a range of stressor conditions.

The primary reason for inclusion of more reflex action information in RAMP is the observation that some reflex actions are central expressions for status of body regulation. Given the binomial nature of mortality observations, we need to know why fish die. They die for many reasons which all seem to point to the loss of physiological regulation; either homeostatic or allostatic regulation. How do we measure regulation?  Allostasis shows us that consideration of homeostatic set points is not sufficient to predict mortality. My view is that vitality is correlated with physiological regulation and that impairment of vitality and regulation leads to mortality when physiological bounds of the species are exceeded. Until we can directly measure the causes for mortality, we rely on measures for vitality based on activity, responsiveness, and injury.

For predicting mortality, I chose to measure vitality over modeling stressors because of the direct relationship between vitality impairment and mortality. Stressor interactions in fisheries can make interpretation of stressor effects on mortality difficult to interpret. Information about stressors in multivariate models for mortality can be used to identify changes in the design of fishing gears that reduce bycatch mortality. Then vitality impairment can be used to evaluate reduction in discard mortality associated with new gears.

Survival of schooling small pelagic fish discarded from purse seine fisheries

Greenback horse mackerel, Trachurus declivis 

Purse seine fishing

Vitality impairment and RAMP can be used to determine survival of discarded schooling small pelagic fish in purse seine fisheries.  When catch is too large, fish are “slipped” for the net and discarded. These discarded fish are usually exposed to some level of hypoxic conditions associated with crowding in the purse seine. Elevated temperature in surface water may be a stressor. Skin abrasion and scale loss can occur in the net. Many small pelagic species (mackerel, sardine, anchovy, smelt, herring) caught in purse seines are obligate or facultative schoolers that reflexively form groups mediated by the optomotor response. Vitality impairment can be tested for individual fish or groups. See Davis and Ottmar, 2006 for testing groups of free-swimming fish. Schooling fish seek the company of species mates, so testing groups of schooling fish is probably the most informative method. How is this testing done and linked with delayed mortality in captive observation tanks?    

RAMP links vitality impairment scores with delayed mortality scores. The RAMP estimate for delayed mortality is only as good as the mortality estimates from captive observation or tagging experiments. How many replicates are needed in captive observation experiments? The purse seine schooling species need to be held in groups. A replicate group size of ten fish is good for schooling. These fish must be held in good water quality and circulation, in a circular tank size that allows schooling. For initial RAMP formulation, you will need 10 replicate groups of ten fish each. Observations of reflex action impairment and delayed mortality should be made over a range of stressor intensities that result in delayed mortality of 0 to 100%. Then replicate vitality impairment scores are linked with replicate delayed mortality scores to form the RAMP which can be validated with further experiments and replication.

Suuronen, 2005  Stressors in capture and escape of fisheries.

Fish can be sampled from any point on the fishing process, depending on the stressors of interest. Reflex action testing can be made on a group of fish held in a circular observation tank big enough for schooling (See Davis and Ottmar, 2006).  Possible reflex actions for testing include: orientation; schooling; rheotaxis; startle response to sound or light; swimming to bottom of tank. Injuries can also be noted; abrasion, scale loss. After testing the replicate group can then be placed in a holding tank and monitored for delayed mortality through five to ten days. 

Herring lose schooling, orientation, and tail beat frequency increases as the purse seine is drawn smaller (Morgan, 2014). Fatigue and hypoxia are possible stressors in purse seines (Tenningen 2014).

For discard species caught in purse seines that are not schooling fish, or are larger schooling fish, individual fish can be tested for vitality impairment.  Reflex actions tested can include: body flex, orientation, eye roll, operculum or mouth clamp, tail grab, righting, startle.  These fish can be tagged for identification and held together for five to ten days in tanks to determine delayed mortality.

Fisheries studies that have used and documented reflex actions or injury for vitality impairment testing

The table presents selected examples of reflex action & injury vitality impairment testing.

See also a list of reflex actions and injury that may be scored for vitality impairment.

Citations:

AFSC, Alaska Fisheries Science Center 2014 Observer Sampling Manual.

Fisheries Monitoring and Analysis Division, North Pacific Groundfish Observer Program. Seattle, WA.

Barkley, A.S. & Cadrin, S.X. 2012. Discard mortality estimation of yellowtail flounder using reflex action mortality predictors. Trans. Am. Fish. Soc. 141:638-644.

Benoît, H.P., Hurlbut, T., and Chassé, J. 2010. Assessing the factors influencing discard mortality of demersal fishes using a semi-quantitative indicator of survival potential. Fish. Res. 106:436-447.

Braccini, M., Van Rijn, J., and Frick, L. 2012. High post-capture survival for sharks, rays and chimaeras discarded in the main shark fishery of Australia? PLoS ONE 7: e32547.

Brownscombe, J.W., Thiem, J.D., Hatry, C., Cull, F. Haak, C.R., Danylchuk, A.J., and Cooke, S.J. 2013. Recovery bags reduce post-release impairments in locomotory activity and behavior of bonefish (Albula spp.) following exposure to angling-related stressors. J. Expt. Mar. Biol. Ecol. 440:207-215.

Brownscombe, J.W., Nowell, L., Samson, E., Danylchuk, A.J., & Cooke, S.J. 2014. Fishing-related stressors inhibit refuge-seeking behavior in released subadult Great barracuda. Trans. Am. Fish. Soc. 143:613-617.

Campbell, M.D., Patino, R., Tolan, J., Strauss, R., and Diamond, S.L. 2010.

Sub-lethal effects of catch-and-release fishing: measuring capture stress, fish impairment, and predation risk using a condition index. ICES J. Mar. Sci. 67:513-521. 

Campbell, M.D., Tolan, J., Strauss, R., and Diamond, S.L. 2010. Relating angling-dependent fish impairment to immediate release mortality of red snapper (Lutjanus campechanus). Fish. Res. 106:64-70.

Danylchuk, A.J., Suski, C.D., Mandelman, J.W., Murchie, J.W., Haak, Brooks, A.M.L., and Cooke, S.J. 2014. Hooking injury, physiological status and short-term mortality of juvenile lemon sharks (Negaprion bevirostris) following catch-and-release recreational angling. Cons. Physiol. 2:cot036.

Davis, M. W. 2007. Simulated fishing experiments for predicting delayed mortality rates using reflex impairment in restrained fish. ICES J. Mar. Sci. 64:1535-1542.

Davis, M.W. & Ottmar, M.L. 2006. Wounding and reflex impairment may be predictors for mortality in discarded or escaped fish. Fish. Res. 82:1-6.

Depestele, J., Buyvoets, E., Calebout, P., Desender, M., Goossens, J., Lagast, E., Vuylsteke, D., and Vanden Berghe, C. 2014. Calibration tests for estimating reflex action mortality predictor for sole (Solea solea) and plaice (Pleuronectes platessa): preliminary results. ILVO-communication. Report nr. 158. 30p. 

Diamond, S.L. & Campbell, M.D. 2009. Linking “sink or swim” indicators to delayed mortality in red snapper by using a condition index. Mar. Coast. Fish.: Dynamics, Manag. Eco. Sci. 1:107-120.

Donaldson, M.R., Hinch, S.G., Raby, G.D., Patterson, D.A., Farrell, A.P., and Cooke, S.J. 2012. Population-specific consequences of fisheries-related stressors on adult sockeye salmon. Physiol. Biochem. Zool. 85:729-739.

Hammond, C.F., Conquest, L.L., and Rose, C.S. 2013. Using reflex action mortality predictors (RAMP) to evaluate if trawl gear modifications reduce the unobserved mortality of Tanner crab (Chionoecetes bairdi) and snow crab (C. opilio). ICES J. Mar. Sci. 70:1308-1318.

Hannah, R.W. and Matteson, K.M. 2007. Behavior of nine species of Pacific rockfish after hook-and-line capture, recompression, and release. Trans. Amer. Fish. Soc. 136:24-33.

Humborstad, O-B., Davis, M.W., and Løkkeborg, S. 2009. Reflex impairment as a measure of vitality and survival potential of Atlantic cod (Gadus morhua). Fish. Bull. 107:395-402. 

McArley, T.J. & Herbert, N.A. 2014. Mortality, physiological stress and reflex impairment in sub-legal Pagrua auratus exposed to simulated angling.  J. Expt. Mar. Biol. Ecol. 461:61-72.

Raby, G.D., Donaldson, M.R., Hinch, S.G., Patterson, D.A., Lotto, A.G., Robichaud, D., English, K.K., Willmore, W.G., Farrell, A.P., Davis, M.W., and Cooke, S.J. 2012. Validation of reflex indicators for measuring vitality and predicting the delayed mortality of wild coho salmon bycatch released from fishing gears. J. Appl. Ecol. 49:90-98.

Stoner, A.W. 2012. Assessing stress and predicting mortality in economically significant crustaceans. Rev. Fish. Sci. 20:111-135.

Stoner, A.W., Rose, C.S., Munk, J.E., Hammond, C.F., and Davis, M.W. 2008. An assessment of discard mortality for two Alaskan crab species, Tanner crab (Chionoecetes bairdi) and snow crab (C. opilio), based on reflex impairment. Fish. Bull. 106:337-347.

Szekeres, P., Brownscombe, J.W., Cull, F., Danylchuk, A.J., Shultz, A.D., Suski, C.D., Murchie, K.J., and Cooke, S.J. 2014. Physiological and behavioural consequences of cold shock on bonefish (Albula vulpes) in The Bahamas. J. Expt. Mar. Biol. Ecol. 459:1-7.

Trumble, R.J., Kaimmer, S.M., and Williams, G.H. 2000. Estimation of discard mortality rates for Pacific halibut bycatch in groundfish longline fisheries. N. Amer. J. Fish. Manag. 20:931-939.

Yochum, N., Rose, C.S., and Hammond, C.F. 2015. Evaluating the flexibility of a reflex action mortality predictor to determine bycatch mortality rates: A case study of Tanner crab (Chionoecetes bairdi) bycaught in Alaska bottom trawls. Fish. Res. 161:226-234.

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.