An Overview of Larval American Lobster, 



Homarus americanus, Sampling Programs 



in New England During 1974-79 



MICHAEL J. FOGARTY' and ROBERT LAWTON 2 



INTRODUCTION 



The American lobster, Homarus americamis, has long 

 generated intense interest, both for its significance to the 

 fisheries of the coastal New England States and Canadian 

 Maritime Provinces, and its importance in the structure of 

 benthic communities in the northwest Atlantic (Cobb and 

 Wang in press). 



Concern over the potential impact of proposed or operating 

 power plants on lobster populations in coastal locations in 

 New England led to several investigations of larval lobster 

 distribution during the last decade. In addition, general studies 

 on lobster population dynamics were undertaken during this 

 period in support of development of a coastwide fishery man- 

 agement program. A lack of adequate knowledge of the distri- 

 bution of lobster larvae, factors affecting larval production, 

 and annual variation in abundance were recognized as serious 

 impediments to understanding lobster recruitment patterns 

 and to estimating potential losses due to entrainment by power 

 plants. 



An ad hoc working group, comprised of scientists from both 

 the private and public sectors, was formed during 1977 to 

 discuss the results of ongoing larval lobster research programs 

 and to provide guidance for the development of future studies. 

 In this report, the results of larval lobster investigations in 

 Maine, New Hampshire, Massachusetts, and Rhode Island by 

 members of the working group are summarized. Aspects of the 

 spatial and temporal distribution of larvae are described and 

 additional information on the diurnal and vertical distribu- 

 tion of lobster larvae and annual variation in production is 

 provided. 



SAMPLING METHODS 



Larval lobster sampling programs were initiated at several 

 coastal locations throughout the New England region during 

 1974-79 (Fig. 1). Prior studies indicated that lobster larvae 

 are concentrated in surface waters during daylight (Temple- 

 man 1937; Templeman and Tibbo 1945; Scarratt 1964, 1973). 

 Accordingly, sampling effort was directed at the air-water 

 interface using neuston gear (Table 1). An opening-closing 

 Tucker trawl (Hopkins et al. 1973) was used for discrete depth 



Rhode Island Department of Environmental Management, 150 Fowler 

 Street, Wickford, R.I.; present address: Northeast Fisheries Center Woods Hole 

 Laboratory, National Marine Fisheries Service, NOAA, Woods Hole, MA 

 02543. 



'Massachusetts Department of Fisheries, Wildlife, and Recreational Vehicles, 

 Division of Marine Fisheries, 100 Cambridge St., Boston, MA 02202. 



sampling in several studies and for both surface and subsur- 

 face hauls in one program (Table 1). Comparison trials be- 

 tween 1 x 2 m neuston gear and a 2 x 2 m Tucker trawl towed 

 at the surface indicated that both nets provided similar density 

 estimates when expressed on an areal basis but neuston net 

 density was approximately 2-4 times higher when expressed 

 on a volumetric basis (Bibb et al. 1983b). These results sug- 

 gest that larvae are concentrated in the upper 0.50-0.75 m of 

 the water column and that the lower depth strata sampled by 

 the Tucker trawl was nearly devoid of larvae. 



Sampling was primarily conducted during daylight hours, 

 however, night samples were occasionally collected in two 

 studies and were consistently taken in Block Island Sound 

 (Bibbetal. 1983a). 



Tow speeds ranged from 1.8 to 5.6 km/h and were from 

 12 to 30 min in duration (Table 1). Tows were often abbre- 

 viated during periods of high ctenophore abundance when the 

 filtration efficiency of the nets was reduced. Sampling periods 

 spanned the known seasonal occurrence of larvae, ranging 

 from May through October depending on year and area 

 sampled (Table 1). 



Cape Cod Canol 



ICOLLINGSETAL] 



Block Island Sound 



(BIBB ETAL, FOGARTYETAL) 



Hampton - Seobrook 



I GRABE ET AL ) 



Cope Cod Bay 



i MATThlESSEN AND SCHERER . 

 LAWTON ET ALi 



COLLINGSETAL) 



Buzzards Boy 

 I LUX ETAL, 



COLLINGS ETAL) 



Figure 1. — Sampling locations for larval American lobster, Homarus americanus, 

 in New England during 1974-79. 



