FISHERY BULLETIN VOL. 82, NO. 2 



stable thermal regime on the outer shelf and the 

 highly varying regime in adjacent inshore waters. 

 During the spring, when inshore water tempera- 

 tures were depressed well below those on the outer 

 shelf, the outer shelf served as a refuge for the 

 warm-temperate species association which occurs 

 largely inshore when water temperatures there 

 become elevated above those on the outer shelf. 



It is also interesting to note that while for the 

 most part the communities observed here are 

 structured by species associations that behave as a 

 group in response to environmental variation, two 

 of the most successful species (Peprilus triacan- 

 thus and Squalus acanthias) are those which show 

 the least permanent group affinities. As noted 

 above, the success of P. triacanthus may be due in 

 part to the species' very wide thermal tolerance, 

 but S. acanthias was one of the more thermally 

 restricted species encountered in the study, being 

 restricted to waters less than 14°C. 



ACKNOWLEDGMENTS 



We would like to thank Marvin Grosslein and 

 the staff of the Groundfish Survey Unit, Northeast 

 Fisheries Center (NEFC) Woods Hole Laboratory, 

 for their helpful assistance in making this data 

 base and supporting information available to us, 

 and also to express our appreciation to the hun- 

 dreds of individuals who have participated in the 

 survey over the years. Eric Foell and William Bly- 

 stone provided a large measure of assistance in 

 data analyses and computer programming, re- 

 spectively. Marvin Grosslein and the staff at 

 NEFC, particularly William Overholtz, provided a 

 helpful review of the manuscript, for which we are 

 also indebted to Jim Price and Eric Anderson of 

 the Virginia Institute of Marine Science. Data 

 analyses for this study were supported by contract 

 No. AA550-CT6-62 of the Bureau of Land Man- 

 agement. 



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