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.

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.”

Human delayed mortality can be predicted using olfactory impairment

Olfactory impairment in humans was measured by error rate in olfaction tests. Increasing number of errors in olfaction tests were related to increasing 5-year mortality rates in a logistic regression (PLoS ONE). 

The human logistic relationship between olfactory impairment and 5-year delayed mortality is a powerful method for predicting delayed mortality and is similar to other animal RAMP relationships between reflex impairment, injury, and delayed mortality. Olfactory impairment can be easily measured in human and animal clinical settings and can easily and automatically be measured in aquaculture contexts by analysis of animal distributions and activity in rearing facilities. Given the fundamental nature of olfaction, one would expect the relationship between olfactory impairment and delayed mortality to be generally present among animal phyla and this can be tested in clinical and field settings.

Pinto et al. 2014 state, “We are the first to show that olfactory dysfunction is a strong predictor of 5-year mortality in a nationally representative sample of older adults. Olfactory dysfunction was an independent risk factor for death, stronger than several common causes of death, such as heart failure, lung disease and cancer, indicating that this evolutionarily ancient special sense may signal a key mechanism that affects human longevity. This effect is large enough to identify those at a higher risk of death even after taking account of other factors, yielding a 2.4 fold increase in the average probability of death among those already at high risk (Figure 3B). Even among those near the median risk, anosmia increases the average probability of death from 0.09 (for normal smellers) to 0.25. Thus, from a clinical point of view, assessment of olfactory function would enhance existing tools and strategies to identify those patients at high risk of mortality.”

(PLoS ONE)

The human study controlled for the mortality effects of age, gender, socioeconomic status, and race. Additionally, “We excluded several possibilities that might have explained these striking results. Adjusting for nutrition had little impact on the relationship between olfactory dysfunction and death. Similarly, accounting for cognition and neurodegenerative disease and frailty also failed to mediate the observed effects. Mental health, smoking, and alcohol abuse also did not explain our findings. Risk factors for olfactory loss (male gender, lower socioeconomic status, BMI) were included in our analyses, and though they replicated prior work [41], did not affect our results.” Note that the study did not control for effects of possible episodic exposure to toxins or injury that may result in temporary or permanent olfactory impairment not related to death.

Olfactory response is an involuntary response to a stimulus, and may be considered a reflex action. In the human study, presence or absence of smell detection for rose, leather, orange, fish, and peppermint were summed and related to delayed mortality. Olfactory responses to various substances can be scored as present or absent and summed to predict delayed mortality. In the same way, the RAMP method is an example of presence-absence scoring with summation of reflex impairment and injury scores to predict delayed mortality.  Measuring and summing whole animal responses, i.e., olfaction, reflex actions, and injury to stimuli is a powerful method for observing the effects of stressors and aging on delayed mortality.   

“We believe olfaction is the canary in the coal mine of human health, not that its decline directly causes death. Olfactory dysfunction is a harbinger of either fundamental mechanisms of aging, environmental exposure, or interactions between the two. Unique among the senses, the olfactory system depends on stem cell turnover, and thus may serve as an indicator of deterioration in age-related regenerative capacity more broadly or as a marker of physiologic repair function [13].”

Clearly, measurement and summation of presence-absence for whole animal involuntary characteristics (olfaction, reflex actions, and injury) is a powerful way to predict delayed mortality in humans and other animals.