DAYS SOAKED 



observed mortality. As noted above, injuries did occur 

 when crab-laden pots were pushed across the ship's rail 

 and over the side. Some legs protruding through bottom 

 meshes were damaged, particularly in the experiment 

 where 150 crab were crowded in each pot. We believe this 

 may have contributed to the mortality observed for both 

 leged-size and undersize crab in that experiment. How- 

 ever, mortalities occurred to both injured and appar- 

 ently uninjured crab. 



Tag Returns 



Returns of tagged crab escaping pots were greater in 

 1975 (30.0%) than during 1974 (16.0%) even though fish- 

 ing effort was somewhat less in 1975 (Tables 5, 6). More- 

 over, we used a two-color, highly visible tag during 1975, 

 which was more likely to attract attention of fishermen or 

 processors than the single-color (dull orange) tag used in 

 1974. 



Recovery of escaped undersize tagged crab was less in 

 all experiments them for legal-size crab. However, there 

 is no evidence that higher tagging loss caused this. On 

 several occasions, fishermen reported seeing a tag on an 

 undersize crab as it was being released into the water but 

 too late to retrieve it. Small crab taken upside down from 

 pots by commercial fishermen were not turned over 

 before release. Thus carapace tags may have been over- 

 looked. Six of the 10 vessels returning most of the 1975 

 tags were among the top 10 vessels returning tags in 1974. 

 These vessel crews were especially alert to the presence of 

 tags on both undersize and legal -size crab. 



Viability of Escaped Crab 



K confinement in pots contributed to crab mortality, 

 either in the p)ots or after escapement, we would expect 

 mortality to be positively correlated with length of soak. 

 No such correlation was observed to the end of confine- 

 ment, but subsequent recovery of tagged crab indicated 

 one correlation. The viability of crab that escaped the 

 pots was tested by comparing recoveries of tagged crab 

 from various experiments using pots with those free- 

 released. The latter crab were promptly tagged and 



Figure 5. — Entry of new king crab (large and small 

 combined) into pots containing herring, dead crab, 

 or no bait. 



released except for the initial group in 1974, which was 

 held for under 2 days in the live tank. All were released in 

 the area where experimental pots were soaking. As a 

 result, free-release crab were distributed at intervals 

 throughout the escape period of crab emerging from 

 soaking pots. 



Statistical tests, based upon the "G" statistic (Sokal 

 and Rohlf 1969), showed no significant difference (30% 

 level) in percentage recovered among 1975 free-releases 

 and 1-4 day confinement for both undersize and legal- 

 size crab. However, jjercentage recovered for both under- 

 size (2 returned from 86 released) and legal-size (21 

 returned from 120 released) crab, 2.3% and 17.5%, 

 respectively, confined for 10-16 days was significantly (P 

 <0.05) smaller than for the free-release groups (34.9% 

 undersize and 35.2% legal size) and those confined for 1-4 

 days (31.4% and 33.1%). Furthermore, the recovery 

 percentage for undersize crab confined 10-16 days was 

 significantly less {P <0.05) than that for legal-size crab 

 confined for the same length of time. Only 1975 data were 

 compared in this analysis to reduce effect of less visible 

 tags used during 1974. 



Incidental Catches 



Those commercial fishermen interviewed agreed that 

 the occurrence of other fish and invertebrate species in 

 crab pots varied widely by fishing location and time of 

 year. At times, fishermen using small-mesh web on their 

 pots captured one or more Pacific cod in each pot lifted; 

 Pacific halibut were taken less often. However, the 

 fishermen reported that under some conditions halibut 

 were present in up to 9% of their commercial pots lifted. 

 All fish, except for viable halibut, were used for crab 

 bait. 



We captured both Pacific halibut and Pacific cod in 

 Chiniak Bay. The remains of eight halibut, ranging in 

 length from 84 cm to 123 cm, and six cod, from about 60 

 cm to 70 cm, were taken from 121 lifts during 1975. Soak 

 time averaged 2 days. Occurrence was 6.6% for halibut 

 and 5.0% for cod. All cod were viable, whereas only one 

 halibut was alive. Six halibut were captured during the 

 1974 tests. Fishing effort, although not recorded, was 

 considerably less than in 1975. 



