COMMERCIAL FISHERIES REVIEW 



Vol. 28, No. 11 



Results : Five hundred crabs - -equal num- 

 ber of males and females --were tagged at each 

 station except Bodega Bay (314 males, 186 fe- 

 males) and Drakes Bay (342 males, 158 fe- 

 males); inall, 1,406 males and 1,094 females. 

 Only active crabs , having both chela intact and 

 missing no more than one walking leg, were 

 tagged. 



5,316 crabs were caught in the 310 traps set: 

 707 legal males, 2,341 sublegal males, and 

 2,268 females. The average catch per trap-day 

 was 17.2 crabs (2.3 legal males, 7.6 sublegal 

 males, and 7.3 females). Drakes and Bodega 

 Bays had the highest catch of legal-sized crabs 

 per trap -day with 10.6 and 3.5. Of total crabs 

 caught, 6.1% of legal males and 38.1% of sub- 

 legal males were in a soft condition. 



Mating marks were found on 409 males; 

 345 on legal and 64 on sublegal crabs. The 

 fertility of females was determined by the 

 presence of sperm in their spermatheca. 

 Forty-four females were checked: 43, or 

 about 98%, were fertile. Ovaries varied in 

 color from light orange to red -orange. 



Distress Signal Recommended 

 for Fishing Vessels 



BCF has developed a distinctive and highly 

 visible banner for use by fishing vessels as 

 a recognition and distress signal. 



The international orange vinyl-coated ny- 

 lon banner with bullseye center measures 10 

 by 5 feet. It should be displayed in the rigging 

 or on top of the wheelhouse whenever an emer- 

 gency or any other situation requires assist- 

 ance. When this signal is displayed, vessels 

 awaiting assistance by the Coast Guard Search 

 and Rescue Branch can be readily identified. 



The signal is a definite aid to searchers 

 when the disabled vessel does not have radio- 

 telephone communication or is not in a group 

 of similar size craft. 



The banner has been shown in New Bed- 

 ford and Gloucester and will be displayed in 

 all major New England fishing ports. 



It is recommended that all commercial 

 fishing vessels carry this distress signal. 



Galveston Records 



Shrimp Culture Gains 



Much new progress in studies of shrimp 

 culture has been made at the Galveston, Texas, 

 laboratory. Both white shrimp andseabobs 

 were successfully reared to postlarvae from 

 eggs spawned in the laboratory. This followed 

 the successfully rearing of brown and pink 

 shrimp --and rounded out the rearing of the 4 

 most important commercial shrimp species. 



The laboratory developed techniques for 

 mass culture that permitted large numbers of 

 shrimp larvae tobe grown under controlled con- 

 ditions for either detailed physiological studies 

 or the stocking of enclosed brackish-water 

 ponds . 



Studies also are under way on the feasi- 

 bility of growing shrimp in ponds under semi- 

 natural conditions. In one experiment, brown 

 shrimp grew from an average size of one -half 

 inch to 3 inches in 120 days. White shrimp in 

 the same experiment grew to 5 inches. This 

 is an average growth of nearly one -quarter 

 inch per week. A second study using 4,000 

 white shrimp spawned and reared to post- 

 larvae in the laboratory showed increases of 

 one -half inch to 4 inches in 90 days in one of 

 the culture ponds. This study is continuing. 



Lobster Research in Boothbay Harbor 



The SCUBA diving team at the Boothbay 

 Harbor laboratory is making extensive ob- 

 servations of lobsters under natural condi- 

 tions in representative areas along the Maine 

 coast. Its findings suggest that lobsters def- 

 initely seek shelter in burrows during day- 

 light hours and occupy much of the available 

 habitat. It may be significant that those lob- 

 sters seen in the open during daylight hours 

 show evidence of attack: missing claws and 

 other appendages. Lobster fishermen and 

 scientists have long observed that certain arti- 

 ficial areas --some rock jetties and the rock 

 sides of the Cape Cod Canal- -have beenheavily 

 colonized by lobsters. So the possibility of in- 

 creasing the amount of lobster habitat exists. 

 However, a recent attempt by Canadian scien- 

 tists to construct an artificial lobster reef 

 has been only moderately successful to date. 



