catch per day in waters deeper than 180 m. 

 than in shoaler waters. This evidence suggests 

 that waters between 100 and 182 m. are the 

 realm of most prerecruit lobsters at Veatch 

 Canyon and that lobsters move gradually to 

 deeper waters as they grow. The catch per 

 hour in shoaler waters was greater during 

 daylight (0600-1800 hours) than at night 

 (1800-0600). Catches averaged 65 lobstersper 

 hour during the day and 28 at night. In depths 

 greater than 182 m. there was no appreciable 

 difference; day tows caught 11 lobsters per 

 hour, night tows 13. Time of day had no effect 

 on the variation of carapace length or the ratio 

 of females to males. 



The depth of fishing at Veatch Canyon has a 

 direct effect on the composition of the catch. 

 Tows during research cruises were made at 

 depths from 100 to 450 m. (55-250 fathoms). 

 As depth increased, the ratio of females to 

 males increased. The linear regression of 

 percentage of females dependent on the depth 

 fished is highly significant (b = 0.131, 

 s b = 0.035, b/st = 3.743, P< 0.01). The same 

 level of significance was obtained with the data 

 from commercial catches. The mean carapace 

 length of lobsters increased with depth, but 

 preliminary results from a tagging study sug- 

 gest seasonal changes in the relation of size to 

 depth. Not enough tows have been made in all 

 months at all depths to show these differences. 



Table 6. — Catch of lobsters by research vessels, Oceanographer 

 Canyon, 1965-67 





Females 



Males 



Total 



Females 



Carapace 

 length 



Percentage 

 of total 

 lobsters 



Berried 



Berried 



Cm. 



Number 



Number 



Number 



Percent 



Number 



Percent 



5 



3 







3 



100.0 











6 



2 



9 



11 



18.2 



— 



— 



7 



8 



15 



23 



34.8 



— 



— 



8 



10 



17 



27 



37.0 



1 



10.0 



9 



19 



16 



35 



54,3 



3 



15.8 



10 



40 



13 



53 



75.5 



6 



15.0 



11 



34 



13 



47 



72.3 



10 



29.4 



12 



44 



21 



65 



67.7 



4 



9.1 



13 



62 



12 



74 



83.8 



13 



21.0 



u 



43 



15 



58 



74.1 



6 



18.6 



15 



26 



9 



35 



74.3 



4 



15.4 



16 



27 



9 



36 



75.0 



7 



25.9 



17 



8 



15 



23 



34.8 







— 



18 



10 



8 



18 



55.6 



1 



10.0 



19 



9 



5 



14 



64.3 



1 



11.1 



20 



1 



4 



5 



20.0 







— 



21 







5 



5 



— 



— 



— 



22 







1 



1 



— 



— 



— 



23 







1 



1 



— 



— 



— 



Totals 



346 



188 



534 



64.8 



58 



16.8 



Table 7. — Samples of the commercial catch of 

 lobsters from Oceanographer Canyon, February 

 1966 to June 1967 



Oceanographer Canyon 



Oceanographer Canyon (lat. 40°25' N., long. 

 68° 10' W.) is 30 km. south of the Southwest 

 Part of Georges Bank and 100 km. east north- 

 east of Veatch Canyon. 



The catches of lobsters during research 

 cruises at Oceanographer Canyon in April and 

 June 1965, April and June 1966, and June and 

 October 1967 are summarized in table 6. Tows 

 were made in depths of 100 to 337 m. (55-185 

 fathoms). 



Differences were not significant between the 

 average numbers of lobsters caught per hour 

 in daylight and at night. Tows in water 182 m. 

 deep or less produced five lobsters per hour 

 during the day and six at night; tows made in 

 deeper water produced 31 per hour during the 

 day and 24 at night. The increase in catch 

 with depth, however, was significant. Here, 

 as in the other areas, the ratio of females to 

 males increased with depth of capture. The 

 increase held between 100 and 235 m. but did 

 not extend beyond 235 m. where percentage 

 females in both the research and commercial 

 samples varied between 65 and 75. 



The most striking difference between Ocean- 

 ographer and Hudson and Veatch Canyons is 

 the preponderance of large lobsters, 12 cm. 

 and more in carapace length. This difference 

 was also evident in commercial samples 

 (table 7). 



Carapace 

 length 



Totals 



Females 



Percentage 

 of females 



Jm. 



Number 



Number 



Number 



Percent 



8 



16 



11 



27 



59.3 



9 



67 



55 



122 



54.9 



10 



91 



43 



134 



67.9 



11 



168 



49 



217 



77.4 



12 



213 



68 



281 



75.8 



13 



260 



89 



349 



74.5 



14 



214 



77 



291 



73.5 



15 



99 



77 



176 



56.2 



16 



84 



59 



143 



58.7 



17 



91 



49 



140 



65.0 



18 



65 



47 



112 



58.0 



19 



34 



33 



67 



50.7 



20 



12 



21 



33 



36.4 



21 



2 



16 



18 



11.1 



22 







5 



5 



0.0 



1,416 699 2,115 



67.0 



At Oceanographer Canyon, as at Veatch 

 Canyon, greater fishing depths produced larger 

 lobsters. The mean carapace length of lob- 

 sters caught was 11 cm. at depths of 182 m. 

 or less, and 13 cm. at depths of 182 m. or 

 more (fig. 4). 



