FISHERY BULLETIN: VOL. 70, NO. 3 



Figure 1. — Annual deviations from the 1940-1959 mean 

 sea-surface temperature at Boothbay Harbor, Maine. 



changes did not appear to have produced any 

 obvious alteration of the general faunal char- 

 acteristics of the Gulf of Maine. During the 

 recent cooling period, there were a number of 

 reports of southward extensions of range and 

 shifts in the distribution of fish and invertebrate 

 fauna: (1) Boyar (1964) reported the occur- 

 rence of the Greenland halibut {Reinhardtius 

 hippoglossoides) off Boothbay Harbor, Maine, 

 in February 1963. This is a southern shoal- 

 water record for this subarctic species. (2) 

 Substantial numbers of capelin (MalloUis villos- 

 us) were caught in the Bay of Fundy in the 

 spring of 1965 (Tibbo and Humphreys, 1966) 

 and have continued to be taken each spring 

 through 1968 (S. N. Tibbo, personal communica- 

 tion). There has been no written record of the 

 occurrence of capelin in this area since 1919 

 (Bigelow and Schroeder, 1953). (3) Since 

 1961, spiny dogfish {Sqimlus acanthias) have 

 been collected with increasing frequency during 

 the winter months in South Carolina coastal 

 waters (Bearden, 1965). This species is uncom- 

 mon south of Cape Lookout, N.C., and there 

 have been no previous records of its occurrence 

 off South Carolina. (4) Collette and MacPhee 

 (1969) reported the collection of an arctic shan- 

 ny {Stichaetts punctatus) in Massachusetts Bay 

 in August 1968. This is the second record of 

 this northern species in the Gulf of Maine and 

 extends the known range 180 miles to the south- 

 west. (5) Finally, the green crab {Carcimis 

 maenas) , which became abundant as far north- 

 east as Nova Scotia in the mid-19.50's, has de- 

 clined in abundance, coincident with the decline 



in temperature. The green crab is now rare in 

 Canada and eastern Maine, but still abundant 

 in southwestern Maine and northern Massachu- 

 setts (Welch, 1968). 



Such observations of northward and south- 

 ward shifts in the abundance and distribution 

 of marine animals have usually been based on 

 sporadic observations and on commercial fishery 

 statistics. The accumulation of records of oc- 

 casional occurrences over a number of years can 

 give the impression of a change in distribution 

 sustained over a period of time. Many of the 

 fluctuations in commercial fishery landings are 

 due to changes in fishing methods, efficiency, 

 effort, and market conditions. As Bell and 

 Pruter (1958) have demonstrated, it is decep- 

 tively easy to infer relationships and draw false 

 conclusions from such data. Given adequate re- 

 search vessel surveys, however, it should be pos- 

 sible to determine the relative abundance and 

 distribution of fish and invertebrate fauna with 

 some precision. In this paper such otter-trawl 

 survey data are used to determine what effect 

 the recent cooling trend has had on the distri- 

 bution of some of the important commercial spe- 

 cies of groundfish in continental shelf waters 

 between Nova Scotia and Long Island. 



A great diversity of pelagic, hemipelagic, and 

 demersal fish species were caught during the 

 otter-trawl surveys. Our initial analysis was 

 limited to the relatively abundant commercially 

 exploited groundfish species felt to be represent- 

 atively sampled by the otter trawl, e.g., those 

 species living on or in close association with the 

 bottom and within the depth limits covered by 

 the surveys (approximately 30-350 m). For 

 this study, four species were selected which rep- 

 resent the basic types of geographic zonation 

 characteristic of the area. The general geo- 

 graphic distribution of these species is as fol- 

 lows: 



AMERICAN PLAICE 

 (HIPPOGLOSSOIDES PLATESSOIDES) 



The plaice is an arctic-boreal species which is 

 found in abundance from Greenland to Cape 

 Cod. In the Gulf of Maine this species is most 

 plentiful in depths ranging from 30 to 200 m. 



638 



