754 



Fishery Bulletin 88(4), 1990 



60* 59' 56* 57' 56' 55' 54* 53° 52° 51° 50° 49° 



59° 58° 57° 56° 55° 54° 53° 52° 51° 50° 



Figure 1 



Map of Newfoumllarid, Canada, show- 

 ing the location of Conception Bay 

 (lower box) and Bonavista Bay (upper 

 box). 



Materials and methods 



From 1979 to 1984, nine research cruises were made 

 to Conception Bay, Newl'oimdland, Canada (47°30'N, 

 53 °W, Fig. 1), to tag 6296 male snow crabs, size range 

 56-135 mm carapace width (CW). An additional 2253 

 male crabs, size range 45-125 mm CW, were tagged 

 during four cruises to Bonavista Bay, Newfoundland 

 (48°50'N, 53°20'W), from 1979 to 1984. 



Crabs were captured using Japanese-style conical 

 traps baited with squid Ille.r illecebrosu!< and set in 

 longlines of twelve traps at depths ranging from 110 

 to 285 m. Traps were hauled after soaking for 24 hours. 



Tagging was conducted in a manner designed to 

 minimize mortality. Traps were spaced approximate- 

 ly 40 m apart, which allowed us to tag crabs from the 

 trap on deck while the other traps remained in the 

 water. Before tagging, we examined each animal and 

 discarded any that appeared injured. Carapace width 

 was measured to the nearest millimeter using vernier 

 calipers. Animals were tagged with a T-bar tag (Floy 



Reference to trade names does not imply endorsement by the 

 National Marine F'isheries Service. N().'\.-\. 



Tag Mfg. Co., Inc., Seattle, WA 98105) and immediate- 

 ly released on location. Details of the tagging procedure 

 are described in Hurley et al. (In press). Tags were in- 

 serted in the posterior ecdysial suture (epimeral line) 

 which was made visible by applying gentle upward 

 pressure to the carai)ace. The tagging location was 

 2-6 mm from the right coxopodite of the last walking" 

 leg. Before releasing the crab, the end of the tag was 

 given a gentle tug. If the tag appeared loose, it was 

 removed and the animal was discarded. To determine 

 measurement errors, one biologist measured 90 

 animals three times in blind trials. The animals ranged 

 in size from 63 to 124 mm. Recaptured animals were 

 obtained mostly from commercial fishermen. Only 

 animals that were examined by a staff biologist were 

 used in the analysis. 



Results and discussion 



Repeated measurements by a biologist of a group 

 of crabs were always within 1 mm of the mean for 

 each animal. Workers studying other species of large 

 Crustacea have suggested that measurements can be 



