New Hampshire Lobster Larvae Studies 



STEPHEN A. GRABE,' JOHN W. SHIPMAN, 2 and WELDON S. BOSWORTH 2 



ABSTRACT 



Lobster larvae, which were collected in coastal New Hampshire waters between mid-July and early October 

 1978 and early June through mid- August 1979, reached maximum abundance in late August in 1978 and late July 

 in 1979. Stage composition was heavily weighted towards stage IV larvae in 1978, and stage I larvae in 1979. 

 The sizes of larvae at all stages were generally larger than those reported in other studies. 



INTRODUCTION 



The only quantitative investigations of lobster larvae in 

 New Hampshire waters have been conducted as part of the 

 preoperational ecological studies for Seabrook Station (Public 

 Service Co. of New Hampshire). Preliminary sampling was 

 undertaken during the summer of 1973 (Normandeau Asso- 

 ciates, Inc.'); formal preoperational studies, described below, 

 were initiated during 1978. Primary questions concerned the 

 seasonal distribution and abundance of lobster larvae in the 

 vicinity of the offshore intake and discharge structures for 

 Seabrook Station. 



MATERIALS AND METHODS 



A neuston net (1 m x 2 m x 8 m; 1 .0 mm mesh) was towed 

 during daylight hours along a north-south transect about 1,850 

 m offshore from Hampton Beach, N.H. (Fig. 1). Samples 

 were collected from 9 June to 18 October 1978 and 15 May to 

 20 September 1979. Collections were made weekly until the 

 first larvae were collected, twice-weekly when larvae were 

 present, and weekly again for a few weeks after larvae were no 

 longer collected. Thirty-four collections were made during 

 1978, 30 during 1979. 



Tow duration was 15 min through 18 July 1978 and was 

 increased to 30 min thereafter; tow speed was = 1 m/s. Tows 

 were made from the side of the boat outside of the wake. The 

 net bottom was 0.5 m below the surface to give an effective 

 sampling area of 1.0 m 2 . Sample volumes, measured by a digi- 

 tal flowmeter, averaged 1,475 m 3 for 15-min tows and 1,868 m J 

 for 30-min tows. If flowmeter readings were suspect (fouled 

 with algae), the average volume calculated for similar tow 

 characteristics (duration and net area) was applied. 



Samples were sorted for all lobster larvae in the laboratory, 

 staged after Herrick (1896) and Templeman (1948a), and 

 measured (stage IV only during 1978). 



Numerical classification (Boesch 1977) was used to compare 

 the stage composition from New Hampshire with that of other 

 New England areas. A similarity matrix, using percent simi- 



'Normandeau Associates, Inc., 25 Nashua Road, Bedford, NH 03102. 



'Normandeau Associates Inc., 25 Nashua Road, Bedford, NH; present address: 

 Dames and Moore, 155 N.E. 100th St., Seattle, WA 98125. 

 03102. 



•Normandeau Associates, Inc. 1 974. Studies on the American lobster, Homarus 

 americanus, in the vicinity of Hampton Beach, New Hampshire, Tech. Rep. V-I, 

 22 p. Prepared for Public Service Co. of New Hampshire. • ). 



larity (Boesch 1977), was constructed for each combination 

 of sites. Group average clustering (Boesch 1977) was then 

 applied to organize these sites into larger groups based on the 

 similarity of larval stage composition. 



RESULTS 



Seasonality and Abundance 



Lobster larvae were first collected in neuston tows on 21 

 July 1978 and 8 June 1979. Stage I larvae were present from 

 late July through mid-August 1978 and from early June 

 through early August 1979 (Fig. 2). There was no distinct sea- 

 sonal peak of stage I larvae during 1978; the collection of 53 

 individuals on 24 July 1979 was coincident with the collection 

 of large amounts of macroalgae. Few stage II (n = 3) and III 

 (n = 3) larvae were collected during 1978-79. Stage IV larvae 

 were collected from 21 July to 3 October 1978 and 17 July 

 to 10 August 1979 (Fig. 3). Peak densities of stage IV larvae 



Figure 1.— Lobster larvae sampling station off Hampton, N.H. 



53 



