326 



FISHERY BULLETIN OF THE FISH AND WILDLIFE SERVICE 



attempt to relate changes in lobster landings to 

 changes in temperature. 



A complete recoi'd of annual landings of lobsters 

 since 1904 is available for Rhode Island in the an- 

 nual reports of the Rhode Island Commissioners 

 of Inland Fisheries (1904-35), and from federal 

 statistics for recent years. These data, smoothed 

 by 5-year moving averages, are presented in figure 

 20 together with January-July differences in 

 water temperatures at Boothbay Harbor, 1906-49. 

 The Boothbay Harbor data, previously shown in 

 figure 8, page 299, have been given an additional 

 smoothing by a moving average of 3. Tempera- 

 tures at Boothbay Harbor were used for this com- 

 parison because they were the only ones available 

 which cover the period of these lobster landings. 

 It has already been pointed out that trends in air 

 and surface water temperatures are quite similar 

 over an extensive range along the Atlantic coast. 



Temperature and landing data indicate a direct 

 relation between water temperature and the 

 availability of lobsters, a relation recently pointed 



out by Martin * for lobster catches in Canada. 

 It is to be noted, however, that the curve of water 

 temperatures in figure 20 represents a tendency 

 toward warming of water conditions along the 

 Atlantic coast in recent years, especially during 

 the winter months, and that the catch of lobsters 

 in Rhode Island has declined in the face of this 

 warming. The relationship discovered by Martin 

 is the reverse : Canadian lobster catches are greater 

 in warmer years. 



Lobster landings for the Middle Atlantic States, 

 for Massachusetts, and for Maine are presented 

 for the years since 1918 in figures 21, 22, and 23. 

 The downward trend in landings for the Middle 

 Atlantic States is similar to that occurring in 

 Rhode Island, while the trends in Massachusetts 

 and Maine have been upward over the same 

 period. 



* Martin, W. R., Long-term prediction based on climatic changes. Manu- 

 script presented at a meeting of the Committee on Biological Investigations, 

 Annual Meeting of the Fishery Research Board of Canada, January 1953. 

 9 pp. 



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1904 1910 1915 1920 1925 1930 



YEAR 



1935 1940 1945 



1950 



Figure 20. — Landings of lobsters in Rhode Island, 1904 to 1949, as 5-year moving averages (solid line), and January- 

 July differences in surface water temperatures at Boothbay Harbor, Maine, as deviations from the mean difference 

 (dotted line). 



