248 



Fishery Bulletin 104(2) 



71 W 70 W 



I ' I 



67'W 



66"W 



65'W 



45''N 



44=N 



71 W 70 W 69 W 68 W 67 W 66 W 65 W 



Figure 1 



Geographical areas of the Maine Department of Marine Resources (DMF) inshore 

 survey program and National Marine Fisheries Services NMFS survey program. 

 ME/NH = Maine and New Hampshire; MA DMF=Massachusetts Department of 

 Marine Fisheries. 



movements in the fall, returning to inshore shallow 

 areas in the spring. 



The range of movement increases further after they 

 reach maturity. However, there are large differences 

 in migratory behaviors among individuals (Pezzack 

 and Duggan, 1986). In general, mature legal-size lob- 

 sters are more abundant offshore and in deeper waters 

 (Harding and Trites, 1989). Large egg-bearing lobsters 

 have been shown to exhibit long migrations (>100 km) 

 (Krouse, 1980; Campbell, 1983). 



Size-dependent inshore-offshore distributions have 

 been reported in many lobster studies (Skud, 1969; 

 Cooper et al., 1975; Briggs, 1985; Campbell and Pe- 

 zzack, 1986; Cobb et al., 1989; Harding and Trites, 

 1989). Information collected in commercial fisheries and 

 scientific surveys has revealed that the spatial distri- 

 bution of the American lobster may be size-dependent 

 and that lobster of large sizes are more likely found in 

 deep waters. This pattern has been identified but not 

 quantified (Wilson, 1998). The spatial distribution of 

 lobsters varies with seasons and scales with the size 

 of lobsters. 



The distribution and abundance of lobsters have been 

 studied with a variety of techniques. Diver and subma- 

 rine and ROV surveys are generally limited to nearshore 

 areas or in temporal resolution. Tagging programs are 

 often limited in area and time covered and in number 



of lobsters tagged and returned. A fisheries-dependent 

 sea sampling program covers a limited number of fish- 

 ing boats within limited areas and thus may not be able 

 to provide an overall picture of lobster distribution and 

 abundance within the lobster stock area in the Gulf of 

 Maine. Until recently, the only comprehensive fishery- 

 independent data were those obtained from the NMFS 

 Gulf of Maine fall and spring trawl surveys. NMFS 

 has conducted a randomized stratified survey since the 

 mid 1960s, but this survey is limited to depths deeper 

 than 50 meters. In fact, the majority of the sampling 

 stations are located in waters deeper than 120 meters 

 as a result of an increased proportion of untrawlable 

 areas and problems with lobster gear in inshore waters. 

 In the fall of 2000, the DMR began a coast-wide inshore 

 trawl survey, which mainly covered waters shallower 

 than 120 meters (Fig. 1). 



The spatial distribution of lobsters is largely restrict- 

 ed to the nearshore areas. Although found throughout 

 the Gulf of Maine, 80% of the landings are estimated 

 to come within three miles from shore (ASMFC, 2000). 

 Clearly the lobster fishery will follow the concentrations 

 of lobsters, although seasonal changes in movements 

 and trapability of lobsters may make less productive 

 fishing areas desirable to limited portions of the fleet 

 at certain times of the year. As the fishing effort for 

 lobster has increased, the traditional inshore fishery 



