Surface tows were made with a 1 x 2 m neuston net with a 

 mesh size of 1.05 mm. All tows were made during daylight 

 hours at a speed of 4.6-5.6 km/h with the top 20 cm of the net 

 breaking the water surface. Tow duration was 30 min and 

 volumetric measurements were calculated from flowmeter 

 readings obtained from a General Oceanics* model S 2030 R 

 flowmeter in the net mouth. The average volume of water 

 strained per tow was 2,793 m 3 . This volume per tow decreased 

 over the 3 yr as a result of high ctenophore and larval crab con- 

 centrations. The numbers of ctenophores and crab larvae in- 

 creased rapidly and reached such high densities in 1976, it 

 became impossible to tow for more than 5 min. By mid- 

 August, sampling had to be terminated. While concentrations 

 remained high enough in 1977 and 1978 to prevent full 30-min 

 tows, shorter tows were possible at many stations. 



A 1 x 1.5 m opening and closing Tucker trawl with 1.05 

 mm mesh similar in design to that described by Clark (1969) 

 and Hopkins et al. (1973) was utilized for discrete depth samp- 

 ling. The net was designed to be fished at a 45 ° wire angle, 

 presenting an effective opening of 1 m : . The net was towed at 

 5.6 km/h for 20 min. 



After completion of a neuston or Tucker trawl tow, samples 

 were washed into a pair of nesting sieves with mesh sizes of 

 1.05 mm and 6.35 mm. Sample concentrate was preserved in a 

 5°7o Formalin-95% seawater solution buffered with sodium 

 borate (Na ; B,0- • 10H ; 0). Samples were returned to the lab- 

 oratory where all lobster larvae were removed and staged 

 according to the descriptions of Herrick (191 1 ). 



^Reference to trade names does not imply endorsement by the National Marine 

 Fisheries Service, NOAA. 



RESULTS AND DISCUSSION 



Neuston Tows 



Four hundred fifty-nine tows were made during 1976-78; 

 9,631 larvae were collected for an average density of 9.9 lar- 

 vae/1,000 m 3 or water filtered (Table 1). The maximum num- 

 ber and density of larvae collected was 746 (266.2/ 1 ,000 m 3 ) at 

 Station F in Buzzards Bay on 21 June 1977. Mean annual den- 

 sities were highest in Buzzards Bay during 1977 and 1978 and 

 highest in the Cape Cod Canal during 1976 (Table 1). Highest 

 mean density (12.8 larvae/ 1,000 m 3 ) over all years was ob- 

 served in Buzzards Bay. 



Abundance and Temporal Distribution 



Hatching in Buzzards Bay commenced during the third week 

 in May and stage I larvae generally disappeared from the water 

 column by mid-July. The peak of stage 1 abundance in mid- 

 June corresponded to the peak of total larval abundance. An 

 initial small peak of hatching was evident during the last week 

 of May. This peak was consistently observed and may be due 

 to earlier hatching of eggs extruded during summer; ova ex- 

 truded during autumn appear to hatch later in the season (Per- 

 kins 1972). Second stage larvae first appeared in samples by 

 the end of the third week in May and peaked in abundance in 

 mid-June. Stage III larvae were usually found in samples by 

 the first of June and peaked in mid-June. Fourth stage larvae 

 were initially collected by the first week of June, peaked in 

 abundance by 1 July, and could, as in 1978, continue to be col- 

 lected into September. 



Larval abundance patterns in the Cape Cod Canal were 

 quite similar to those found in Buzzards Bay, although a bi- 



Table 1. — Lobster larval tow data for three areas for 1976-78. 







Total 



Volume 













Number of 



number 



of water 



Number of 



Average 



Number 



Mean larval 





stations 



of 



sampled 



tows with 



volume 



larvae 



density 



Area 



sampled 



tows 



(m 1 ) 



larvae 



(m'( 



collected 



(no./l,000 m>) 



1978 

















Buzzards Bay 



5 



90 



154,858 



40 



2,561 



1,563 



10.1 



Cape Cod Canal 



3 



58 



115,972 



30 



2,686 



430 



3.7 



Cape Cod Bay 



_2 



34 



69,085 



17 



2,442 



115 



1.7 





10 



182 



339,915 



87 



2,578 



2,108 



6.2 



1977 

















Buzzards Bay 



10 



103 



257,264 



68 



2,714 



4,035 



15.9 



Cape Cod Canal 



3 



50 



88,272 



23 



2,883 



654 



7.4 



Cape Cod Bay 



_3 



36 



S4.9K8 



23 



2,717 



672 



7.9 





16 



189 



430.524 



114 



2,759 



5,361 



12.5 



1976 

















Buzzards Bay 



3 



31 



80,137 



15 



3,343 



687 



8.6 



Cape Cod Canal 



3 



43 



90,353 



22 



3,170 



1,428 



15.8 



Cape Cod Bay 



1 



14 



35,468 



_8 



3,698 



47 



1.3 





7 



88 



205,958 



45 



3,314 



2,162 



10.5 



All years 

















Buzzards Bay 



10 



224 



492,259 



123 



2,739 



6,285 



12.8 



Cape Cod Canal 



3 



151 



294,597 



75 



2,889 



2,512 



8.5 



Cape Cod Bay 



_3 



84 



189.541 



49 



2,769 



834 



4.4 





16 



459 



976.397 



247 



2,793 



9.631 



9.9 



37 



