128 
Fishery Bulletin 11 6(2) 
Table 1 
Reflexes used to assess vitality of Dungeness crab (Cancer magister) when applying the reflex action mortality predictor 
approach for predicting discard mortality, as detailed in Yochum et al. (2017), along with the method for assessment and 
metrics for determining whether a given reflex is present (a state that includes weak responses) or absent. Reflexes were 
assessed in the order (1-6) shown. 
Order 
Reflex 
Method 
Present 
Absent 
1 
Eye retraction 
A probe is used to lightly tap 
the top of an eye 
Crab retracts the eye 
downward 
Crab does not react, leaving 
the eye in place 
2 
Mouth defense 
A probe is used to attempt 
to pull the 3 rd maxillipeds 
forward 
Crab defends its mouthparts 
with its chela making it diffi¬ 
cult to access the maxillipeds 
Crab allows its maxillipeds to 
be manipulated 
3 
Chela closure 
A probe is placed below the 
chela dactyl 
Crab reacts by closing the 
chela tightly, then opening it 
again without manipulation 
Crab does not open and close 
its chela without manipulation 
4 
Leg wrap 
A probe is used to pull pereo- 
pods 2-4 to a 180° angle 
Crab draws the pereopods 
back in (i.e., joints at less 
than a 180° angle) 
Crab pereopods do not move 
without manipulation 
5 
Leg curl 
Pereopod 5 is straightened 
and pulled downward 
Crab pulls up and curls its 
pereopod in a controlled 
manner 
Crab does not move the pereo¬ 
pod without manipulation 
6 
Abdomen response 
A probe is used to attempt to 
pull the top of the abdominal 
flap away from the crab’s body 
Crab exhibits a strong, agi¬ 
tated reaction 
Crab does not react 
edge, anterior to the tenth anterolateral spine, not in¬ 
cluding the spines) may be retained in the commercial 
fishery, and at or above 146 mm (5.75 in) in the recre¬ 
ational fishery. Legal-size, soft-shell males are also typ¬ 
ically discarded to allow them to harden and fill with 
flesh after molting (PSMFC 7 ; ODFW 8 ). Through logis¬ 
tic regression modeling, Yochum et al. (2017) estimated 
delayed discard mortality rates (i.e., the proportion of 
discarded animals that die within 5 d of release) for the 
commercial ocean fishery and recreational bay fisheries 
(both from a boat and shoreside, i.e., fishing from land 
rather than a boat, often from a dock or pier). The goal 
of the tagging study described here was to ascertain 
whether 1) the laboratory study reported by Yochum et 
al. (2017) under- or over-estimated the true mortality 
rates for discarded Dungeness crab, 2) whether there 
are long-term, chronic effects (attributed to persistent 
impairment) that lead to delayed mortality that were 
obfuscated by using short-term monitoring, and 3) 
whether the impact from the return to water during 
the process of discarding, a stressor not incorporated in 
the laboratory study, contributes to mortality. Crab are 
susceptible to cracked carapaces or fatal injuries (or 
7 PSMFC (Pacific States Marine Fisheries Commission). 
1978. Dungeness crab project of the state-federal fisher¬ 
ies management program, 139 p. Pac. States Mar. Fish. 
Comm., Portland, OR. 
8 ODFW (Oregon Department of Fish and Wildlife). 2015. 
2015 Oregon sport fishing regulations, 100 p. Oregon Dep. 
Fish Wildl., Salem, OR. 
both) when being dropped from a vessel, dock, or pier. 
Mortality attributed to this impact could therefore ex¬ 
plain differences in rates estimated between laboratory 
and tagging studies and would suggest the importance 
of including this variable in an estimation of mortal¬ 
ity to improve accuracy. Through this research, we also 
aimed 4) to evaluate tag-return methods for estimating 
mortality rates based on RAMP scores. 
Materials and methods 
Laboratory-holding study 
For the laboratory-holding study (see Yochum et al., 
2017 for details), between February 2012 and April 
2014, crab intended for discard were assessed during 
22 commercial fishing trips by an accompanying scien¬ 
tist (“ride-alongs”) along the Oregon coast. During the 
same period, an additional 26 recreational fishing trips 
were completed on a boat in Yaquina Bay (in Oregon), 
and sampling of the recreational shoreside fishery was 
completed on 15 occasions at the Port of Newport Pub¬ 
lic Fishing Pier (Yaquina Bay). A systematic random 
sample of crab from the commercial fishery, and all 
“recreationally” caught crab were assessed when they 
would have been released (i.e., after all handling pro¬ 
cesses), typically within 10 min of being landed (usu¬ 
ally sooner). Crab assessments (completed in less than 
1 min per crab) included the following variables: sex, 
