FISHERY BULLETIN: VOL. 83, NO. 4 





^ 

 ^ 



1.0r 



.8 - 



.6 - 



.4 - 



.2 - 







^ -- in oj 



o o o o 



o m o 

 m 





1- 



o 



oooppoo oooQoP ooo ooo 



CO to -^ C\J 



o o o o 



<T> (£> a O) . 



oOooooooooooooooooooooooOooooo 

 ~' ro^(Ch-ro<M<Mioio<DCvjioto^aO'^*ir)ODif> 



OfOinototficDO^ioto 



tmio-^cvjiOcvj — toT-^tofO 

 - -ooo - 



ro cvj po iT) 



STATION 



Figure 2.— Typical dendrogram, autumn 1966, showing duster station groups and dissimilarities. Dashed line indicates 



a dissimilarity of 0.65. 



RESULTS 



Five important assemblage groups were present 

 on Georges Bank from fall 1963 to 1978. For refer- 

 ence, w^e name these groups: Slope and Canyon, 

 Intermediate, Shallow, Gulf of Maine Deep, and 

 Northeast Peak. A consistent spatial pattern 

 emerged as consecutive fall cruises were examined 

 and plotted. The same five groups appear to have 

 been present in similar locations since 1963. These 

 five assemblages were present at the mid- and end- 

 points of the fall time series also (Fig. 3). The groups 

 appear to change their spatial configuration slight- 

 ly on an annual basis, but the general area of each 

 group was maintained. Lists of the dominant species 

 in each assemblage are given in Ikble 2. 



The total area that each assemblage encompass- 

 ed through time (years) was delineated by pooling 

 the observations from consecutive years. Figure 4 

 shows an example of a representative assemblage 

 from the spring and fall, respectively. The groups 

 overlapped surprisingly little through time with the 

 exception of a few border stations along adjacent 

 assemblages. 



Table 2.— Assemblage species associations from 

 cluster results (demersal species only). 



Slope and canyon: 



Silver hake 



White hake 



Red hake 



Gulf stream flounder 



Offshore hake 



Fourspot flounder 



Blackbelly rosefish 



American goosefish 

 Intermediate: 



Winter skate 



Little skate 



Red hake 



Silver hake 



Atlantic cod 



Haddock 



Sea raven 



American goosefish 



Ocean pout 



Longhorn sculpin 



Yellowtail flounder 

 Shallow: 



Winter skate 



Little skate 



Silver hake 



Atlantic cod 



Haddock 



Pollock 



White hake 



Red hake 



Summer flounder 



Yellowtail flounder 



Winter flounder 



Windowpane 



Longhorn sculpin 



Sea raven 



Ocean pout 



Sand lance 



American goosefish 

 Gulf of Maine Deep: 



Thorny skates 



American plaice 



Witch flounder 



White hake 



Silver hake 



Atlantic cod 



Haddock 



Cusk 



Atlantic wolfflsh 

 Northeast Peak: 



Thorny skate 



Atlantic cod 



Haddock 



Pollock 



White hake 



Winter flounder 



Ocean pout 



Longhorn sculpin 



510 



