FISHERY BULLETIN: VOL. 70, NO. 2 



Table 2. — Coastal distribution of the number of recently- 

 hatched larval herring from late September to mid-Oc- 

 tober and from then to early November; water temper- 

 taures are from mid-October. 



(1925) reported that herring spawned in the 

 western area later than in the eastern sector of 

 the coast. Hatching of larvae in the spring was 

 observed only once; three larvae (8-9 mm) were 

 captured in the Boothbay area in May. 



The earlier hatching in the eastern sector of 

 the coast may be attributed to the distribution 

 of water temperature. The average surface 

 temperature from 1963 through 1965 was 9.1 °C 

 in the western sector of the coast and 6.2 °C in 

 the eastern sector. Bottom temperatures during 

 the same period averaged 4.5 °C in the western 

 sector and 5.6°C in the eastern. Each year the 

 surface water was 2° to 3.5°C warmer in the 

 western than in the eastern sector, while the 

 eastern bottom water was 1° to 1.5 °C warmer 

 than in the western sector. These temperature 

 trends were established primarily in the summer 

 (Graham, 1970a) and persisted into the autumn 

 (Table 2) . Possibly, cooler autumn surface tem- 

 peratures in the eastern sector would initiate 

 spawning sooner than in the western sector; 

 warmer bottom temperatures would incubate the 

 eggs faster (Das, 1968, see footnote 2). 



SEASONAL ABUNDANCE, DISTRIBUTION 

 AND MOVEMENTS 



Larvae were most numerous in the catches 

 throughout the coast in the autumn, reached a 

 low in the winter, and increased slightly in the 

 spring (Figure 2) . Catches were largest in the 

 eastern sector of the coast in early autumn, but 

 larger in the western sector by mid-autumn. By 

 late autumn, catches dropped drastically in both 

 sectors and reached a common level throughout 

 the coast. In the Boothbay area the numbers of 



COASTAL AREA 

 N- 26,502 



20 • 



18 



16 



E 

 O 



10 



.-CAPE ANN- PENOBSCOT BAY 



-PENOBSCOT BAY- MACHrAS BAY 



OCT. NOV. DEC. JAN. FEB. MAR. APR. MAY 



BOOTHBAY AREA 



N= 7,42<1 



OCT. NOV. DEC. JAN. FEB. MAR. APR. MAY 



Figure 2. — Upper panel - mean catch rates of larval 

 herring in the western (Cape Ann-Penobscot Bay) and 

 eastern (Penobscot Bay-Machias Bay) sectors of the 

 coast during cruises from 1962-67. Lower panel - mean 

 catch rates from the Boothbay area for semimonthly 

 periods combined for the years 1964-67. Points are 

 plotted at the midpoint of the cruise periods. 



310 



