Squires (1968) reported that P. borealis occurred 

 together with P. montagui in depths < 200 m in the 

 Gulf of St. Lawrence and southwest of Newfound- 

 land, but at depths between 200 and 300 m with a 

 smooth detritus bottom and temperatures of 4°-6°C, 

 only P. borealis were caught; in colder temperatures 

 (-1° to 3° C) in this same depth range, P. montagui 

 were more abundant. Pandalus montagui was 

 described as a more eurythermal and eurybathic 

 species than P. borealis. Of all the pandalids in the 

 northwest Atlantic, P. montagui is the only one 

 which inhabits colder Arctic waters < 1.5°C (Squires 

 1966). The Atlantic subspecies of P. montagui has 

 been the subject of several biological studies 

 (Mistakidis 1957; Allen 1963; Couture and Trudel 

 1969a, b). 



Dichel&pandahis leptoceru^ is distributed in the 

 northwest Atlantic from Newfoundland to North 

 Carolina (Rathbun 1929). It has not been reported 

 from the northeast Atlantic and is rare in the north- 

 ern Pacific (Squires 1966). During a November 1956 

 bottom trawl survey in New England waters, D. lep- 

 tocerus was much more widely distributed than P. 

 montagui or P. borealis (Wigley 1960). Dichelopan- 

 dalus leptoceru^ was also found over a broad depth 

 range (33-340 m), but was common between 35 and 

 145 m and at temperatures (in November) of 

 5°-20°C, whereas P. montagui occurred primarily 

 between 70 and 135 m and at temperatures of 

 6°-10°C. Dichelopandalu^ leptocerus was also col- 

 lected in areas where bottom sediments contained 

 low, medium, and high quantities of organic matter, 

 whereas P. montagui appeared to be associated with 

 sediments with relatively low organic content. Thus, 

 in several ways, D. leptocerus appears to have less 

 restricted habitat requirements than P. montagui (or 

 P. borealis). No detailed biological studies of D. lep- 

 tocerus have been published. 



The Maine Department of Marine Resources con- 

 ducted an exploratory bottom trawl survey to deter- 

 mine the abundance and distribution of pandalid 

 shrimp populations in Penobscot Bay (Figure. 1) dur- 

 ing 1980-81. During the course of this survey, 

 biological data were collected from about 10,000 

 shrimp. The objective of this paper is to describe im- 

 portant life history characteristics of P. montagui 

 and D. leptocerus in Penobscot Bay (the Bay); these 

 include breeding seasons, female sizes and ages at 

 maturity, sex transition, growth, longevity, and 

 migratory behavior. Aspects of the life cycle and 

 reproductive biology of each species were examined 

 as functions of time of year, depth, and location 

 within the Bay. 



FISHERY BULLETIN: VOL. 83, NO. 3 



METHODS 



The survey was conducted over the course of a 

 12-mo period from late November 1980 to early 

 October 1981. Samples were collected during five 

 distinct periods of time at 19 different stations 

 located from Cape Jellison in the northern end of 

 Penobscot Bay to Mark Island, a distance of about 37 

 km (23 mi) (Fig. 1). Stations were established at 

 depths ranging from 12 m (40 ft) to 84 m (280 ft) and 

 were located in areas of trawlable bottom. Since a 

 primary objective of the survey was to stimulate 

 commercial shrimp fishing, no attempt was made to 

 randomly select station locations, depths, or sam- 

 pling times. Attempts were made, however, to 

 return to each station as often as possible so as to 

 determine the seasonal variation in the relative 

 abundance of different sexes, reproductive stages, 

 and size groups of each species at individual locations 

 over the course of the year. Adjacent, well-defined, 

 length groups were assumed to represent successive 

 age-groups. 



A total of 45 successful tows (i.e., tows that were 

 not aborted because of bottom obstructions, damage 

 to the trawl, or gear malfunction) were made during 

 the entire survey. Of these, 37 tows which could be 

 assigned to a specific area, depth range, and sam- 

 pling period were selected for data analysis. Area 1 

 was defined as the upper Bay, area 2 as west of 

 Islesboro, area 3 as south of Islesboro, and area 4 as 

 east of Islesboro; depth ranges were defined as 

 shallow (12-25 m), moderate (25-50 m), and deep 

 (50-85 m) (Table 1). The distributions of sampling ef- 

 fort between stations by sampling period, area, and 

 depth range are shown in Table 2. No data were 



Table 1.— Definitions of coded sampling periods, areas, and 

 depth ranges, 1980-81 Penobscot Bay shrimp survey. 



Sampling 

 periods 



1 

 2 

 3 



4 



5 



Areas 



1 

 2 

 3 



4 



Depth 

 ranges 



1 

 2 

 3 



20 November-2 December 1980 



21-29 January 1981 



24-31 March 1981 



16 July-18 September 1981 



5-6 October 1981 



Upper Bay: stations 2, 3, 4, 6, 18 



West of Islesboro: stations 1, 5, 9, 10, 14 



South of Islesboro: stations 7, 8. 12, 15, 16, 17, 



19 

 East of Islesboro: stations 11. 13 



12-15 m (shallow) 

 25-50 m (moderate) 

 50-85 m (deep) 



220 



