Yochum et al. A comparison of methods for evaluating mortality of discarded Cancer magister 
129 
Figure 1 
Photograph of a Dungeness crab (Cancer magister) tagged with a double t- 
bar anchor tag (TBA-LEVO) for this study in which Dungeness crabs were 
tagged and released between October 2012 and April 2014 off the coast of 
Oregon and in Yaquina Bay, Oregon 
shell hardness (“soft”: little or no hardening after molt¬ 
ing; or “hard”: nearly fully hard to near molt), cara¬ 
pace width, presence of new injuries, and amount of 
time spent out of water before assessment. In addition, 
each crab was evaluated for presence or absence of the 
6 RAMP reflexes established for assessing Dungeness 
crab vitality (Table 1) and was given a reflex impair¬ 
ment score (“score”) equal to the number of absent re¬ 
flexes (0-6; both weak and strong reflex responses were 
considered present reflexes). During sampling, 12% of 
crab intended for discard (n = 1065), representing all 
impairment scores, were transported to a laboratory 
for holding to determine mortality rates. Owing to an 
observed captivity effect for crab of all scores (includ¬ 
ing score-0 crab), a crab was considered a “mortality” 
only if it died within the first 5 d of holding. 
Tag-return study 
During the aforementioned sampling trips, beginning 
in October 2012, we aimed to tag and release all crab 
not intended for laboratory holding that were also not 
too small or soft to tag. Crab were tagged with a lime 
green double ‘t-bar’ anchor tag (TBA-LEVO, Hallprint 
Fish Tags, 9 Hindmarsh Valley, Australia; Fig. 1), the 
same tag type that was used for identification purposes 
9 Mention of trade names or commercial companies is for iden¬ 
tification purposes only and does not imply endorsement by 
the National Marine Fisheries Service, NOAA. 
in the laboratory holding study. Details of tag selection 
and tagging procedure are provided in Yochum (2016). 
Tagged crab were released at location of capture, in a 
manner that attempted to mimic the discard process of 
a fisherman. Care was taken to randomize and balance 
the number of crab that were tagged and released vs. 
returned to the laboratory, over different combinations 
of score, sex, and shell hardness (Table 2). The same 
data obtained for held crab were collected for those 
tagged and released. 
An extensive outreach campaign began before the 
commencement of the tag-return study and was a fo¬ 
cal part of the project throughout its duration. To en¬ 
courage the participation of fishermen (Pollock et al., 
2001), for each tag returned (either the physical tag 
or a picture of the tag was required) fishermen were 
given $20, a hat or a shirt, and an entry ticket for 
2 cash-prize raffles that took place in October 2013 
and August 2014. Outreach efforts to make fishermen 
aware of the rewards and project included the follow¬ 
ing: frequently talking with fishermen (captains and 
crew) at the docks (and elsewhere) and inquiring if 
they had tags to return, regularly posting flyers at lo¬ 
cal docks and in fishing and marine supply stores, and 
taking additional measures detailed in Yochum (2016). 
Oregon Sea Grant provided the location where fisher¬ 
men could return tags and collect rewards in person. 
We hoped that this arrangement would encourage tag 
returns given that this organization and location are 
well known and frequented by fishermen, and because 
