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.

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. 

A bigger picture: factors and traits that contribute to vitality and survival of discards in fisheries

ICES WKMEDS4 report (2015)

A conceptual model for discard survival in fisheries is developed in the ICES WKMEDS4 report (2015). In this concept, survival is linked to species sensitivity, injury, and predation, through fishing factors, environment, and size. The expanded view shows potential factors and traits in more detail.

ICES WKMEDS4 report (2015) Click on images.

Sport catch and release (C&R) fishing: assessing captured fish condition (vitality) with injury and reflex impairment

Fix.com (2015)

A review and synthesis of tools and tactics for best practices in sport C&R fishing is made by Brownscombe et al. (2017). A key factor for conservation of species fished with C&R is the assessment of fish condition (vitality) and associated survival after release. This assessment is conducted primarily with observation of injury and reflex impairment that results from fishing practices. Fishers can then make educated adjustments to their fishing practices (capture gear, playing time, handling, release, recovery, or harvest) to enhance future species recruitment in sport fisheries.

Reflex tests for C&R fishing, Brownscombe et al. (2017).

Brownscombe et al. (2017) concluded that “As catch-and-release grows in popularity, so must angler education and implementation of best angling practices to ensure the sustainability of this practice and conservation of fish and aquatic environments. Sustainable catch-and-release angling is a joint venture where it is the responsibility of management agencies and scientists to communicate and evaluate the best angling practices, while anglers need to be educated and use the correct tools and tactics to maximize the likelihood that released fish survive. In this regard, catch-and-release angling is perhaps among the most successful and rewarding conservation partnerships.”

C&R practices, Thousand Islands Life (2014).

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."