NOTES Ojeda and Dearborn Populations of fishes and crustaceans in the Gulf of Maine 



407 



< 



Q 



O 



z 



A. L O 



B S T E n s 



c 



FISH 



Be 



R A B S 



2 4 6 8 10 12 14 16 18 20 

 D E P T H (m) 



D. GUNNERS 



2 4 6 8 10 12 14 16 It 20 

 D E P T H (m) 



30 



20 



O '0 



a. 

 Ill 



OD 



2 



z 



1 4 t I 10I2M 1619 20 



D E P T H (m) 



Figure 3 



Bathymetric distribution in 

 the abundances of lobsters 

 (A), crabs (B), benthic fish 

 (C), cunners (D), and num- 

 l_ier of shelters (E) in the 

 underwater transects con- 

 ducted at Pemaquid Point, 

 Maine. Each vertical bar 

 indicates ±2 SE. Asterisks 

 in D indicate juvenile indi- 

 viduals. 



cods, and lobsters and crabs. Lobsters and crabs, how- 

 ever, occurred earlier than these fishes. Crab species 

 are included in this group because their abundance was 

 extremely low during winter, and the few individuals 

 that remained were not active. Summer-fall resident 

 species moved into shallow water or became active 

 (crabs) when the water temperature increased to 

 8-12°C, generally reaching maximum abundance in 

 midsummer or early fall. The second component was 

 the "regular residents," species captured or observed 

 active at any season, such as sea ravens, rock gunnels, 

 and winter flounders. These species, however, were 

 generally much less abundant than the summer-fall 

 residents (Table 1). The third temporal component of 

 this fauna was the "summer periodicals" (sensu Tyler 

 1971), and refers to those species that occurred period- 

 ically in the samples during summer. The most abun- 

 dant and conspicuous species in this group were mack- 

 erel, spiny dogfish, bluefish, and, less abundantly, black 

 seabass and yellowtail flounder (Table 1). Finally, there 

 was a group of species that occurred at infrec}uent in- 

 tervals and in low numbers during this study. Fish 

 species belonging to this group have been called "occa- 

 sionals" (Tyler 1971) and include shad, little skate, 

 lumpfish, scup, smelt, Atlantic herring, sUver hake, and 

 tomcod. 



Spatial patterns 



The abundances of most groups of mobile predators in- 

 creased with depth, as did the number of shelters (Fig. 

 3). The number of adult lobsters significantly increased 

 with depth in the first 8 m, then remained relatively 

 constant thereafter to 19 m depth (one-way ANOVA, 

 P<0.01; a posteriori SNK test; Fig. 3A). There was 

 no relationship between depth and lobster size, since 

 both large and small individuals were observed at all 

 depths along the transects. Crab species (mostly Cancer 

 irroratus and C. boralis) showed a somewhat differ- 

 ent bathymetric pattern (Fig. 3B). Their abundance 

 markedly increased between 2 and 5 m depth, remained 

 relatively constant at 5-11 m, and decreased at depths 

 greater than 14 m (one-way ANOVA, P<0.01, a pos- 

 teriori SNK test). The collective abundance of benthic 

 fishes (e.g., cunners, rock gunnels, radiated shannys, 

 sculpins, and flounders) progressively increased along 

 the bathymetric gradient, reaching highest density at 

 the deeper zone (18-20 m depth; one-way ANOVA, 

 P<0.01; a posteriori SNK test) (Fig. 3C). A large pro- 

 portion of these fish, however, were cunners which 

 comprised about 80% of the total number of individuals 

 observed in the transects. Cunners exhibited a distribu- 

 tion pattern similar to the one described for total fish 



