Figure 10.--Itotating tank used to measure the swimming speeds of herring. 



times larger outside than inside Pas- 

 samaquoddy Bay. The seasonal abundance 

 of plankton varied greatly. The vernal 

 crop of phytoplankton extended from late 

 March to late June, while the largest 

 volumes of zooplankton were taken during 

 the summer months. Phytoplankton 

 "bloom" ended abruptly in the summer 

 while zooplankton populations decreased 

 more slowly and were at their lowest ebb 

 during the spring. 



The stomachs of 1,696 herring taken in 

 1958 were examined for kinds and quan- 

 tities of food organisms. The importance 

 of plankton in the diet of the herring 

 varied according to the availability of 

 food in different localities. Copepods 

 were the main food items, but the diet 

 was quite diversified, and about 50 dif- 

 ferent organisms were identified. No 

 correlation was found betw^een standing 

 plankton crop and feeding activity. A 

 period of low feeding activity extended 

 from March to August, while from Sep- 

 tennber to November feeding activity was 

 high. There was no apparent relation 

 between plankton abundance and commer- 

 cial catches of herring. 



Exploratory fishing.- -Exploratory fish- 

 ing was carried on during 1957 and 1958 

 to provide additional information on the 

 movements of herring, to supplement 

 shore sampling program, and to locate 

 unexploited herring populations. Elec- 

 tronic detection equipment and various 

 kinds of fishing gear were used. 



Exploratory fishing operations con- 

 firmed the presence of a large spawning 

 population of herring on the northern 

 edge of Georges Bank in the autumn and 

 located small quantities of postlarvae in 

 inshore areas of eastern Maine in the 

 spring. Weekly sonic- sounder cruises 

 during the summer months in 1957 and 

 1958 showed that, in general, the largest 

 concentrations of herring in the Quoddy 

 Region were in open waters where there 

 are no weirs. Attempts to catch these 

 fish with midwater trawls and gill nets 

 were unsuccessful but large quantities 

 were taken by commercial purse seiners. 

 The species of fish taken in the Kennebe- 

 casis and Long Reach areas of the Saint 

 John River were the same as those 

 common to the Quoddy Region. 



15 



