Hydrography 



The circulation patterns in the Gulf of Maine determine the distribution of 

 much of the fauna of the marine system in coastal Maine. Density, Coriolis 

 force pressure (the force due to the rotation of the earth on its axis), drag, 

 and boundary configuration are the primary parameters controlling circulation. 

 Temperature and salinity determine the density of marine waters. "Temperature 

 (and probably salinity to a lesser extent)... in some way affects survival of 

 whole populations of young fish, perhaps through affecting their food supply 

 or rate of growth and, consequently, their resistance to adverse environmental 

 conditions" (Taylor et al. 1957). Fluctuations in mackerel, lobsters, 

 whiting, and yellowtail flounder abundance were found to be correlated with 

 fluctuations in sea water temperature (Taylor et al. 1957). Other 

 environmental factors have been correlated with catches of commercially 

 iniportant fisheries but temperature is the parameter most frequently used, in 

 part due to the existence of long and continuous records (e.g., in the Gulf of 

 Maine; Iselin 1939; Redfield 1939; Carruthers 1951; Templeman and Fleming 

 1953; Chase 1955; Colton and Temple 1961; Dow 1964a, 1964b, and 1977; Martin 

 and Kohler 1965; Flowers and Saila 1972; Dickson and Lee 1972; lies 1973; 

 Gulland 1965; and Sutcliffe et al. 1977). 



Long-term continuous temperature records have been maintained in Maine only at 

 Boothbay Harbor (region 2), since 1906, and at St. Andrews, New Brunswick, 

 Canada, (near region 6), since 1921. Short-term and intermittent data have 

 been collected at other sites along the coast by various government agencies 

 (e.g., Kangas 1974). Published mean monthly temperature records and seawater 

 densities (from which salinity can be determined) are published for stations 

 at Eastport (since 1930), Bar Harbor (since 1947), Pulpit Harbor (1945 to 

 1946), and Portland (1922 to 1945 and since 1956; U.S. Department of Commerce 

 1972). Salinity values have been obtained daily at Boothbay Harbor since 

 1966. 



The most comprehensive physical oceanographic study of the Gulf of Maine was 

 conducted by Bigelow (1927) from 1912 to 1925. Subsequent studies on the 

 hydrography of the Gulf generally substantiate Bigelow' s findings. Summaries 

 of more recent studies are given in Colton (1964), Bumpus (1973), and Hopkins 

 and Garfield (1979). Although a number of studies have been conducted in the 

 Gulf of Maine, sufficiently detailed data to determine more than the broad 

 generalized circulation patterns are not available. This scarcity of data 

 precludes a more specific discussion. 



Long-term temperature trends . Temperature has a major influence on the 

 distribution of most organisms. The Gulf of Maine is subject to long-term 

 temperature trends. These trends are particularly important in the 

 characterization area, where many species are at the northern or southern 

 limit of their ranges. 



In inshore coastal areas, based on records from Boothbay Harbor, annual mean 

 surface temperatures have varied over a 9"F (5° C) range since 1906. Mean 

 annual temperatures recorded at Boothbay Harbor from 1906 through 1978 are 

 illustrated in figure 4-4. The 5-year moving average of sea surface 

 temperatures (figure 4-4) illustrates the fact that until the early 1940s mean 

 annual water temperatures were generally below approximately 47° F (8.3 oc). 

 Since this time, mean annual water temperatures have been above 4/ F. During 



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