406 



Fishery Bulletin 88|2). 1990 



Figure 2 



Seasonal variations in the abundance of 

 lobsters (A), crabs (B), and benthic fish 

 (C) along bathynietric underwater tran- 

 sects at Pemaquid Point, Maine. Each 

 vertical bar indicates \'l SE. 



The abundance of major components of the catch- 

 lobsters, crabs, and benthic fishes— also varied sea- 

 sonally (one-way ANOVA, P<0.01 for all species; Fig. 

 2). Maximum abundances of lobsters occurred in sum- 

 mer (July-September) at densities of 5-8 individuals 

 per transect (~1 adult lobster per 26 m-) (Fig. 2 A). No 

 lobsters were observed in the winter transects (Febru- 

 ary 1986). The seasonal distribution of lobsters close- 

 ly follows the seasonal variation in water temperature 

 (compare Figures lA and 2A). Highest densities of 

 crabs, however, occurred in late fall (November) 1985, 

 with ~14 individuals per transect (~1 adult crab per 

 12 m"), and during the summer of 1986, though their 

 densities were markedly lower than those observed in 

 1985 (~5 crabs per transect or ~1 crab per 33 m^) 

 (Fig. 2B). Few crabs were observed in winter; of those 

 observed, most remained inactive and semiburied in the 

 sand. 



Benthic fish such as cunners, rock gunnels, sculpins, 

 shannys, flounders, and rays were markedly most 

 abundant during fall months, reaching densities of ~75 

 individuals per transect in 1985 and ~60 in 1986 (Fig. 



2C). Their abundance decreased significantly in winter 

 to 2-4 fish per transect, and progressively increased 

 from mid-spring (May- June) until fall as temperature 

 increased. Exhaustive underwater surveys for large 

 predators were carried out in winter (February 1986) 

 with the aid of underwater lights. No cunners or lob- 

 sters were observed along these transects despite the 

 special care taken to examine crevices, caves, and 

 spaces underneath boulders and rocks. In addition to 

 a few crabs, three species of fish were commonly ob- 

 served along these winter transects: rock gunnels, sea 

 ravens, and winter flounders. Rock gunnels were the 

 most abundant fish species, and they were usually ob- 

 served up to 20 m depth, often associated with clumps 

 oi Modiolus modiolus. During the rest of the year, this 

 fish species was rarely found at depths greater than 

 10 m. 



This mobile predator assemblage can be divided into 

 distinctive seasonal components. The first is comprised 

 of "summer-fall residents," species consistently pres- 

 ent from late spring until late fall, including pollock, 

 cunners, longhorn and shorthorn sculpins, grubbys. 



