Banning fishery discards and using RAMP

European Union fishery ministers have agreed to phase out the practice of discarding unwanted or regulated animals (bycatch) from landed catches.  The practice of discarding bycatch can be tremendously wasteful of fishery resources including fish, elasmobranchs, invertebrates, birds, amphibians, reptiles, and mammals.

Discarding, Richard

Banning discarding from fisheries requires total retention of animals caught, which must be landed and processed.  As many of these discarded species are of low economic value, efforts are made to design fishing gears that avoid catching bycatch species in the first place.

Suuronen 2005

A key assumption in the ethical design of fishing gears that do not catch bycatch and discarded species is that animals survive gear encounters. Escaping animals must have significant survival rates after gear encounters if they are to continue contributing to recruitment and ecosystem function. If animals escape from fishing gears and do not survive, they are the same problem as discards in fisheries, except that they are hidden.

Suuronen 2005

Measurement of mortality rates for discards and for animals that escape from fishing gears is vital to the management of fisheries, as they represent a significant form of fishing mortality. Discard and escapee mortality rates have been difficult to measure and new, effective methods are needed.

Viability estimates for Pacific halibut bycatch, based on vitality codes (1-4) for injury and activity have been incorporated into fisheries management for several years.  Recent research results by Benoît et al. 2012 on discard mortality have suggested methods based on fishery-scale sampling with semi-quantitative vitality codes (excellent-1, good-2, poor-3, and moribund-4) and conditional reasoning.

Benoît et al. 2012. Post-capture survival probability over time (h) for five southern Gulf of St. Lawrence marine fish taxa (panels), as a function of their pre-holding vitality class score (colours). The shaded areas represent the 95% confidence band for the Kaplan–Meier empirical survival curve for each vitality class, plotted up to the time at which the last observation was made for a given taxon and vitality level. The lines represent the fits of the selected model for each species and vitality class. For cod and plaice, the fits for models M3 and M4 are presented using solid lines and dashed lines respectively (note that these lines largely overlap). The location of the circles along the line and the size of the circles indicate respectively the times at which observations were censored and the proportion of censored observations for the taxon and vitality level at that time.

Reflex impairment measured by RAMP is a quantitative measure of vitality that gives increased resolution and accuracy to the determination of health and survival of discards and animals encountering and escaping fishing gears. Future research on this subject can benefit from the incorporation of fishery-scale sampling of RAMP for discards and for animals escaping from fishing gears.

The banning of discarding will make the evaluation of mortality rates for animals escaping from fishing gears especially important. "Out of sight and out of mind" will not be a viable strategy with regards to evaluating fishing mortality for gears engineered to enhance escape of bycatch species.

Using RAMP to help automate aquaculture operations

Net pen for fish culture (NOAA).

Aquaculture of animals in tanks and net pens requires monitoring and maintenance of vitality, health, and normal behavior for efficient and economic operations. Presently, health is monitored by sampling for disease outbreaks, while vitality and behavior are observed by aquaculture technicians during the course of their daily activities of feeding, cleaning, and operation of facilities.

Inside net pen for fish culture (NOAA).

In tanks and net pens, animals can swim and feed normally. They can also respond to stimuli administered inside their rearing environment, such as light flashes, sound bursts, food scent, and touch. Responses to these stimuli can be in the form of reflex actions such as startle, orientation, depth distribution, aggregation, and dispersal. These reflex responses can be observed remotely and automatically using video, infra-red, and sonar technology in light and dark conditions. Reflex responses can be recorded and summed as RAMP scores for measures of impairment and correlation with mortality.

RAMP can be a quantitive measure of animal state and be used to help automate aquaculture monitoring and maintenance. When impaired responses to stimuli are observed, alarms can be triggered and technical staff can be alerted to changes in animal vitality, health, and behavior. Then on site alteration of operations can bring rearing conditions back to nominal states and return animals and their reflex actions to vitality and health.

Future research in aquaculture can consider the use of RAMP and automated reflex testing for development of efficient operation protocols and quality assurance. RAMP can also be used as a research tool for testing and validating new designs for aquaculture operations that optimize animal vitality and health.

Field validation of dungeness crab RAMP underway

Crabs tell us about their vitality, using the language of reflex impairment and RAMP.

Yochum

Field validation of dungeness crab RAMP measures for discard mortality are underway off Newport, Oregon.  These field trials with combined RAMP measurements, fishery conditions, and mark and recapture experiments are a large scale field effort to develop RAMP tools for quantification of bycatch mortality (NOAA 2013).

Undersize Dungeness crab marked with a green T-bar spaghetti tag and released as part of the RAMP field validation experiment. The tag is inserted through the suture at the back of the carapace so that it can be retained through a molt. Picture and caption from Stoner and Yochum, 2013.

Pink and Chum Salmon reflex impairment at spawning grounds

A study by Raby et al. 2013 has shown remarkable resilience by Pink and Chum Salmon to simulated fisheries capture stress incurred upon arrival at spawning grounds.  These salmon species were observed to have low mortality and successful spawning after being stressed by exposure to exhaustive exercise, air, and injury.  In the authors words:

"Our study results provide evidence that, after reaching spawning areas, both Pink and Chum Salmon may be resilient to certain forms of capture-related exhaustion stress. Short of producing immediate mortality through extended anoxia, Pink and Chum Salmon are apparently able to recover from substantial physiological disturbance related to capture and ultimately spawn. Natural prespawn mortality rates for Pink Salmon (6.5%) and Chum Salmon (3.2%) in the channel during the study year (R. Stitt, Fisheries and Oceans Canada, personal communication) were nearly identical to the prespawn mortality rates for fish subjected to our capture and tagging procedures."

One of the objectives of the study was to test for possible relationships between reflex impairment (RAMP) and mortality.  However because of the general lack of mortality in these salmon species just prior to spawning, increasing reflex impairment as RAMP was related to increasing intensity of capture stressors and not to mortality or spawning success.   

Patterns of impairment are shown by the authors:

"The pattern of impairment of individual reflexes with successively increasing levels of overall reflex impairment (RAMP scores) was largely consistent. Tail grab and body flex were by far the two most easily impaired reflexes (Tables 2, 3). However, in Chum Salmon, tail grab impairment predominated body flex impairment at low RAMP scores (0.2, 0.4) compared with Pink Salmon. Orientation was typically the third reflex to become impaired for both species when overall RAMP score increased beyond 0.4 (Tables 2, 3). We did not commonly observe VOR impairment, which was almost always the last reflex impaired."

The authors suggest that radical shifts in metabolism during preparation for spawning may be responsible for the observed resilience to simulated capture:

"We hypothesize that Pink and Chum Salmon are resilient to capture-related exhaustion upon reaching spawning areas because of a combination of low water temperature (about 12^◦C in this study) and a physiological shift towards increased use of anaerobic pathways during their final weeks of life. The capture and release of fish arriving at the spawning ground does not appear to influence survival, in contradiction to the results of other studies, which focused on earlier components of Pacific salmon spawning migrations."

The possible shifting of metabolic pathways in prespawning Pink and Chum Salmon, associated with lack of mortality at high levels of reflex impairment is a cautionary tale for use of RAMP to predict vitality, mortality, and spawning fitness. The relationships between reflex impairment, metabolic pathways, and life history traits are important subjects for future research and validation.