Quantification and reduction of unobserved mortality rates for snow, southern Tanner, and red king crabs (Chionoecetes opilio, C. bairdi, and Paralithodes camtschaticus) after encounters with trawls on the seafloor

Rose, Craig S.; Hammond, Carwyn F.; Stoner, Allan W.; Munk, J. Eric; Gauvin, John R.

doi:10.7755/fb.111.1.4

Cited by 13 publications

(11 citation statements)

References 7 publications

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“…Advantages of the RAMP approach have made it an increasingly utilized methodology. It has successfully been used on a variety of species, including fishes (Barkley and Cadrin, 2012;Brownscombe et al, 2013;Davis, 2007;Davis and Ottmar, 2006;Humborstad et al, 2009;Raby et al, 2011) and invertebrates (Chilton et al, 2011;Hammond et al, 2013;Rose et al, 2013;Stoner et al, 2008;Stoner, 2012b) In addition to estimating bycatch mortality rates, RAMP can be used as a tool for the development, modification, and evaluation of fishing gear and techniques to mitigate incidental effects of fishing (conservation engineering) through quantifying bycatch mortality rates Rose et al, 2013).…”

Section: Reflex Action Mortality Predictormentioning

confidence: 99%

“…A research study was completed using RAMP to compare mortality rates for unobserved Tanner and snow crab bycatch in the Bering Sea with different trawl gear configurations. Rates were determined by applying RAMP methodology to crab that had encountered a trawl, and subsequently were captured in an auxiliary net behind the trawl immediately after passing under trawl groundgear and then brought on deck for assessment Rose et al, 2013). Assessments from crabs captured with the auxiliary nets, but with no groundgear exposure, were used to account for effects of capture and handling.…”

Section: Case Study: Discarded Tanner Crabmentioning

confidence: 99%

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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

2015

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a b s t r a c tTo quantify total fishing mortality it is necessary to incorporate mortality rates attributed to bycatch, including animals that are discarded and that interact with the gear without being caught. The Reflex Action Mortality Predictor (RAMP) approach has been increasingly used to determine bycatch mortality rates in fisheries. This methodology creates a RAMP that relates reflex impairment to probability of mortality. As the RAMP approach becomes more prevalent it becomes important to evaluate the efficacy of its application. We evaluated the flexibility of this methodology by creating a RAMP for Tanner crab (Chionoecetes bairdi) discarded from the groundfish bottom trawl fishery in the Gulf of Alaska and comparing it to a previously established RAMP for unobserved Tanner crab bycatch (encountered gear and remained on the seafloor) from the bottom trawl fishery in the Bering Sea. The two RAMPs and the overall mortality rates calculated using these predictors were comparable. However, we detected significant differences between RAMPs. While probabilities of mortality were similar between the two studies for crab with all or no reflexes missing, discarded crab with intermediate reflex impairment had lower mortality probabilities than those from the unobserved-bycatch study. Our results indicate that a RAMP may produce more accurate mortality estimates when applied to animals experiencing similar stressors as those evaluated to create the RAMP, through similar methodology.

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Section: Reflex Action Mortality Predictormentioning

confidence: 99%

Section: Case Study: Discarded Tanner Crabmentioning

confidence: 99%

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

2015

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“…Mortality rates could be overestimated because of agonistic interactions or predation among captive animals, suboptimal temperature or water quality, density of animals in holding enclosures, or failure to meet other biological or environmental requirements of the captive animal (Simonson and Hochberg, 1986;Kondzela and Shirley, 1993;Wassenberg and Hill, 1993;Spanoghe and Bourne, 1997;Portz et al, 2006;Weltersbach and Strehlow, 2013). Alternatively, mortality rates could be underestimated because mortality resulting from an animal's inability to obtain food or avoid predation is not incorporated in such studies (Durkin et al, 1984;Uhlmann et al, 2009;Benoît et al, 2010;Urban, 2015).…”

Section: A Comparison Of Laboratory-holding and Tagreturn Methods Formentioning

confidence: 99%

“…Despite limitations of captive holding, RAMP relationships have commonly been created by using onboard holding tanks or laboratory-based holding facilities (Davis, 2007;Stoner et al, 2008;Humborstad et al, 2009;Barkley and Cadrin, 2012;Stoner, 2012;Hammond et al, 2013;Rose et al, 2013;Depestele et al 2 ;McArley and Herbert, 2014;Humborstad et al, 2016). Preference for this approach is largely due to advantages over alternative methods, which include providing scientists with control and allowing them to differentiate causes of mortality, observing degradation in health and changes in behavior, and knowing the time of death (Davis and Ryer 3 ).…”

Section: A Comparison Of Laboratory-holding and Tagreturn Methods Formentioning

confidence: 99%

A comparison of laboratory-holding and tag-return methods for evaluating delayed mortality of Dungeness crab (Cancer magister) discarded in Oregon fisheries

Yochum¹,

Stoner²,

Sampson³

et al. 2018

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Abstract-The delayed mortality rate of crab discarded during fishing operations can be under-or overestimated in laboratory holding experiments, given the unnatural conditions and the short-term duration of these experiments. To evaluate the extent to which a method affects accuracy in these estimations, we compared mortality rates established through laboratory holding with mortality inferred from a yearand-a-half long tag-return study of Dungeness crab (Cancer magister) discarded in Oregon crab fisheries. The reflex action mortality predictor (RAMP) approach, which relates reflex impairment to probability of mortality, was applied in both studies. Similar patterns in mortalityand tag return-rates with respect to fishery, sex, reflex impairment, shell hardness, and injury from the 2 studies lends support to the reliability of the laboratory-generated mortality rates. However, results suggest that mortality rates determined in captivity are likely underestimated when crab are dropped a distance of greater than 6 m (and potentially less) back to water. This underscores the importance of determining the contribution to mortality of variables in the capture, handling, and discard process that are not incorporated in a study to estimate mortality of discarded animals. Both studies also highlighted the significance of sample size when applying the RAMP approach to a fishery with low rates of discard mortality.

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“…Recent underwater video camera observations of snow crab encountering the traditional footgear (i.e., rockhopper) of a shrimp trawl demonstrated that snow crab are quickly overtaken by the trawl, with approximately 54% of individuals observed experiencing an encounter with the footgear (Nguyen et al 2014). Rose et al (2013) demonstrated that the mortality of decapod crabs in response to such encounters with trawl footgear can range from 10% to 31% depending on the species and region of the footgear they encounter. Subsequent work by Hammond et al (2013) showed that simple modifications to trawl footgear (i.e., rubber disk footgear with off-bottom sweeps or bridles) achieved a 36% and 50% reduction in mortality levels for Tanner crab (Chionoecetes bairdi) and snow crab (C. opilio), respectively.…”

Section: Introductionmentioning

confidence: 99%

Comparative fishing to evaluate the viability of an aligned footgear designed to reduce seabed contact in northern shrimp bottom trawl fisheries

Winger

Munden

Nguyen

et al. 2018

Can. J. Fish. Aquat. Sci.

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Abstract:We developed and evaluated an innovative trawl technology that reduces seabed contact while targeting northern shrimp (Pandalus borealis) off the east coast of Canada. The innovative footgear, referred to as the "aligned footgear", was evaluated in a flume tank to estimate contact area with the seabed and then tested at sea for engineering performance and catchability. Results demonstrated that the aligned footgear trawl produced a substantial reduction (i.e., 61%) in the predicted contact area with the seabed compared with the identical trawl equipped with traditional rockhopper footgear. A total of 20 paired tows (n = 40 tows) were subsequently conducted at sea to evaluate fishing performance. The aligned footgear trawl caught significantly more northern shrimp (+23%), capelin (Mallotus villosus) (+71%), and Greenland halibut (Reinhardtius hippoglossoides) (+99%) compared with the traditional rockhopper bottom trawl.Résumé : Nous avons mis au point et évalué une technique novatrice de pêche au chalut qui réduit le contact avec le fond marin en ciblant la crevette nordique (Pandalus borealis) au large de la côte est du Canada. Le bourrelet novateur, appelé « bourrelet aligné », a été évalué dans un bassin à circulation d'eau afin d'estimer l'aire de contact avec le fond marin, puis a fait l'objet d'essais en mer pour évaluer la performance technique et la capturabilité. Les résultats démontrent que le chalut à bourrelet aligné entraîne une réduction importante (c.-à -d. 61 %) de l'aire de contact prévue avec le fond marin par rapport au même chalut équipé d'un bourrelet sauteur classique. Un total de 20 traits appariés (n = 40 traits) ont ensuite été effectués en mer afin d'évaluer la performance de pêche. Le chalut à bourrelet aligné a pris des quantités significativement plus grandes de crevettes nordiques (+23 %), capelans (Mallotus villosus) (+71 %) et flétans noirs (Reinhardtius hippoglossoides) (+99 %) que le chalut de fond à bourrelet sauteur classique. [Traduit par la Rédaction]

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Quantification and reduction of unobserved mortality rates for snow, southern Tanner, and red king crabs (Chionoecetes opilio, C. bairdi, and Paralithodes camtschaticus) after encounters with trawls on the seafloor

Cited by 13 publications

References 7 publications

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

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

A comparison of laboratory-holding and tag-return methods for evaluating delayed mortality of Dungeness crab (Cancer magister) discarded in Oregon fisheries

Comparative fishing to evaluate the viability of an aligned footgear designed to reduce seabed contact in northern shrimp bottom trawl fisheries

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