STUDIES ON THE) STRIPED BASS OF THE ATLANTIC COAST 43 



season in such a place as the Niantic River, where striped bass are caught so con- 

 sistently at approximately the same temperature in the spring and fall, are mainly 

 winter residents, but it is also known that migratory individuals are present at the 

 times of the earliest and latest catches. It is of interest to note that during October 

 and November 1936, a time which was characterized by sudden drops in temperature, 

 it was plainly indicated that with each cold snap, and resultant decline in temperature 

 of the water, some of the striped bass in the Niantic River moved out and their place 

 was almost immediately taken by fish that presumably came from farther up the 

 coast. Such changes in the population were definitely observed on at least two 

 occasions, both immediately following sharp drops in temperature. Strong winds 

 and storms in the fall also play a part in causing the fish to undertake their migrations. 



The maximum temperatures for this species appear to be in the neignborhood of 

 25°-27° C. (77.0°-80.6° F.), for in New England waters in the latter part of August 

 and early September 1937 when there was a protracted period of exceptionally warm 

 weather (see fig. 30), dead bass in considerable numbers were reported simultaneously 

 in Connecticut and Massachusetts. Such mortality occurred chiefly in shallow- 

 water estuaries where the water temperatures reached especially high levels. A 

 number of dead bass were observed by the author in the Niantic and Thames Rivers 

 at this time, and an examination of them disclosed no parasites or injuries that might 

 possibly have been fatal. The water analyses of the Connecticut State Water Com- 

 mission taken at various intervals in the Thames River near New London , Conn. — an area 

 where many dead bass were found — showed nothing unusual nor the presence of any 

 toxic substances during this period (see table 21). There also was a marked migra- 

 tion of bass that normally spend the entire summer in the Niantic and Thames Rivers 

 out to the cooler coastal waters at the time the water temperatures were so high. 

 This was shown by the recapture of tagged fish outside, and by the almost complete 

 absence of bass in the rivers where they are usually found at this time of year. In 

 view of such facts, the evidence is strong that a temperature of 25°-27° C. (77.0°- 

 80.6° F.) marks the maximum tolerance limit. This is a water temperature which 

 is seldom exceeded over the entire range of the striped bass. 



It is of some interest to note that although a considerable number of striped bass 

 weighing from 5 to 25 pounds were marked by external disc tags, there have been no 

 returns from these fish save in the immediate locality at which they were released 

 and within a short time after marking took place. Returns of tagged fish from any 

 other area then the general point of release have been confined to individuals not 

 more than 4 years old. It is difficult to account for this circumstance, and, although 

 it may be that the larger bass did not take such a great part in the migrations as the 

 younger individuals, information as to the size-categories appearing in commercial 

 catches in previous years does not make it seem likely that this is an adequate expla- 

 nation. By the same token, it is improbable that the larger fish migrate in waters 

 farther offshore, thus reducing the chances of their being caught along the coast. 

 It is possible that the larger individuals do not carry the external disc tags as well as 

 the smaller fish, and that the tags are not retained for more than a short while. It is 

 true that the larger the bass the nearer the top of the back the pin bearing the tags 

 must be inserted, because the breadth of the fish makes it impossible for pins only 

 1% inches long to penetrate to the other side far below the dorsal contour. Other 

 reasons for the lack of returns of the larger tagged fish are, first, the overwhelming 

 abundance of the members of the dominant 1934 year-class, and second, the tendency 

 of the smaller size-categories — 2- and 3-year-olds — to school heavily. This schooling 

 instinct, or schooling "synaprokrisis" (Parr, 1937), tends to make them much more 

 available to commercial fishermen than the larger individuals which are not so strongly 

 inclined to congregate together. The heavy schooling of the smaller fish of definite 

 size-categories was observed countless times in the course of seining for tagging 

 purposes in 1936 and 1937. That these schools tend to travel considerable distances 

 without breaking up is suggested by the recapture in several instances at the same 

 time and in the same area some distance away from the original point of release of 

 two or three fish that had previously been tagged in a single seine haid in the Niantic 

 River. 



