186 



Fishery Bulletin 98(1 



relative efficiency of our 2-m beam trawl on offshore 

 nursery areas for juvenile flatfish and other demer- 

 sal species was unknown, although it was likely that 

 our trawl was relatively inefficient but consistent 

 in collecting demersal fishes. Consistent inefficiency 

 among trawl samples would not affect the general 

 patterns that we found but could have led to under- 

 estimation of abundances. 



For a trawl to be efficient, demersal fishes must re- 

 main near the bottom. Recently settled juveniles 

 of some species, such as M. bilinearis, have been 

 shown to make nightly excursions away from the 

 bottom to feed (Fahay, 1974). For a fusiform juvenile 

 like M. bilinearis this ability is not surprising. How- 

 ever, the pleuronectiform P. ferrugineus has been col- 

 lected well off the bottom on the Grand Banks, not 

 only as larvae but also as juveniles (Frank et al., 

 1992). These "pelagic juveniles" were of the same 

 size classes (10-34 mm) as the postmetamorphic 

 flounder we collected on the bottom with a 2-m beam 

 trawl in our study. In extensive studies in the MAB 

 with comparable or larger midwater sampling gear, 

 few P. ferrugineus larger than 15 mm were collected 

 (Morse, 1989; Cowen et al., 1993). For the NYE, how- 

 ever, juvenile P. ferrugineus do not appear to exhibit 

 such trawl-avoiding behavior. This regional differ- 

 ence in vertical distribution of >20-mm postmeta- 

 morphic young may be due either to differences in 

 the temperature structure of the water column (i.e. 

 depth of optimal temperature, as discussed above) 

 or to some other unknown latitudinal difference 

 in developmental rate, settlement size, or behavior 

 (Miller et al., 1991; Fuiman and Higgs, 1997; Osse 

 and Boogaart, 1997). 



In summary, age-0 demersal fishes utilize the con- 

 tinental shelf of the NYB as both settlement and 

 nursery habitat. According to our findings, the shelf 

 of the NYB can be divided into three broad nursery 

 areas (inner, middle, and outer shelves) and can 

 be described by species assemblage as well as by 

 hydrography. There is a need for more research con- 

 cerning the quality of habitats for age-0 fishes in 

 the NYB. Information on smaller-scale variation in 

 habitat for age-0 fishes may be just as revealing 

 as that for larger macrobenthos (see Auster et al., 

 1991). Manned submersibles may be used to deter- 

 mine such small-scale habitat associations, even for 

 small juveniles. Differences in growth rates of given 

 species among habitats should also shed light on 

 habitat quality within the NYB. Nursery habitats 

 play an important role in the life history of marine 

 fishes, and knowledge gained about the distribution 

 and quality of these areas for commercially impor- 

 tant offshore species should help to improve man- 

 agement of these areas.. 



Acknowledgments 



We thank all those who have contributed to the vari- 

 ous aspects of this work. The fieldwork was made 

 possible with the help of numerous volunteers, par- 

 ticularly Mark Sullivan and Teresa Rotunno. Cap- 

 tain Mark Phillips and the crew of the FV Illusion 

 gave much to the practical aspects of the cruises. 

 This manuscript benefited from critical reviews from 

 Tom Grothues, Ken Able, and Robert Cerrato, as well 

 as from valuable discussions with Michael Fahay, Al 

 Stoner, and Brenda Norcross. Supplemental tempera- 

 ture data for August 1996 was kindly provided by Jack 

 Jossi. This paper resulted from research sponsored by 

 the National Oceanic and Atmospheric Administra- 

 tion's Saltonstall-Kennedy program, award number 

 NA66FD0012. The views expressed herein are those 

 of the authors and do not necessarily reflect the views 

 of NOAAor its subagencies. 



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