Figure 8. --Movements of herring as shown by tagging. The straight lines connect the areas of tagging to 

 points of recovery but do not show lines of traveL 



12.5 pounds per square inch per second. 

 Predicted pressures and rates of pres- 

 sure change between turbine intakes and 

 exits are therefore within the liinits 

 which these fish can withstand. The effect 

 of increase in pressure from the top of 

 the draft tube to its lowest point was not 

 investigated but anticipated pressure 

 changes are unlikely to injure the fish. 



Herring held in a large mesh-covered 

 cage responded to the movement of water 

 through the cage by heading into the 

 current and swimming from side to side 

 in the "upstream" direction. The re- 

 sponse seemed to be based on visual 

 stimuli, but its effectiveness was limited 

 by the mciximum swimming speed. With 

 increasing water velocities, herring con- 

 tinued to swim against the current until 

 forced backward, tail first. Swimming 

 speeds increased with size of fish and 

 ranged from 2,4 to 4.7 feet per second 

 (1.4 to 2.8 knots) for herring with mean 



lengths of Z^ to 1 0|^ inches. Swimming 

 endurance also increased with size of 

 fish. Herring 74 inches long were able 

 to stem currents of 3.4 feet per second 

 for a period of 13 minutes. 



Examinations of echo-sounder records 

 showed that during the fishing season from 

 May to October the median depth of 

 herring shoals varied from 26 to 35 feet 

 during the day and from 17 to 23 feet at 

 night. 



£arly Life History. --There were 33 

 cruises (1,404 plankton tows) from Sep- 

 tember 1956 to February 1959 throughout 

 the Bay of Fundy and Gulf of Maine to 

 study distribution and abundance of herring 

 larvae as indicators of spawning grounds 

 and nursery areas, and to discover sur- 

 vival, growth, and methods of transport 

 of herring to the Passeimaquoddy area. 

 There were two main spawning grounds: 



13 



