NOTES Ojeda and Dearborn: Populations of fishes and crustaceans in the Gulf of Maine 409 



provide large mobile predators with microhabitats for 

 shelter against predation, and bases for reproductive 

 activities and nursery grounds. Of particular relevance 

 in these environments is the spatial heterogeneity of 

 the bottom. Large rocks and boulders which typically 

 occur at depths greater than 10 m at the study site are 

 important microhabitats for territorial predatory spe- 

 cies such as cunners and lobsters (Pottle and Green 

 1979, Ennis 1984a). The increased number of lobsters 

 and fish (mostly cunners) observed along the bathy- 

 metric gradient is probably related to the availability 

 of such microhabitats (see Figure 3). As shown else- 

 where (Ojeda and Dearborn 1989), the substrate hetero- 

 geneity at Pemaquid Point progressively increases wnth 

 depth as bottom irregularities such as cracks, crevices, 

 holes, and rocks become more common. In addition to 

 microhabitat availability, the observed bathymetric 

 distribution of large predators may represent an avoid- 

 ance response by these species to strong water turbu- 

 lance and wave surge that commonly affect the shal- 

 lower end of this subtidal zone (especially at low tides). 

 The occurrence in this study of numerous juvenile 

 pollock and cod provides a good example of the impor- 

 tance of shallow, rocky, subtidal zones as nursery 

 grounds as shown by MacDonald et al. (1984) and Keats 

 et al. (1987). Juvenile pollock were the most abundant 

 species of the nearshore fish assemblage (Table 1). 

 These findings, in addition to feeding data presented 

 elsewhere (Ojeda 1987), suggest that pelagic fish 

 species may play important roles in rocky nearshore 

 benthic communities by affecting the distribution and 

 abundance of their benthic prey. Moreover, the one- 

 way offshore migration exhibited by these species 

 indicates that they may be important linkages in 

 the transfer of energy from nearshore to offshore 

 ecosystems. 



Acknowledgments 



This paper represents a portion of the Ph.D. disserta- 

 tion submitted by F.P.O. to the Department of Zool- 

 ogy, University of Maine, Orono. We are grateful to 

 Drs. Hugh DeWitt, Bob Elner, Bill Glanz, Fabian 

 Jaksic, Irv Kornfield, and Les Watling, and to Dave 

 Tapley for critically reading this paper. We appreciate 

 the diving-assistance and logistic support given by 

 I. Babb, M. Dunn, P. Garwood, C. Gregory, J. Guy, 

 S. Hacker, D. Knowles, M. Lesser, C. Moody, G. Pod- 

 niesisnski, B. Richardson, K. Scully, D. Tapley, 

 R. Vadas, and R. Wahle. This research was funded by 

 grants from the Migratory Fish Research Institute 

 (MFRI), the Graduate Student Board (GSB), and the 

 Department of Zoology (all of them to F.P.O.) of the 

 University of Maine, Orono. The work of F.P.O. at 



the University of Maine was funded by an ODE PLAN 

 Chilean Scholarship, by a University Graduate Re- 

 search Fellowship, and by the Center for Marine 

 Studies of the University of Maine. 



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