3 5^ Memoir Sears Foundation for Marine Research 



Another large parasite, the copepod Lernaeenicus radiatus (LeSueur), buries its 

 horns in the flesh on various parts of the fish's body, most commonly along the back 

 {137 '• 480). This parasite sometimes approaches a length of two inches and has a pre- 

 dominant reddish color, which makes it very conspicuous. Other copepods listed 

 by Wilson as parasitic on B.tyrannus are: Bomolochus teres Wilson, Caligus schistonyx 

 Wilson, Caligus cheliferWilson, Pandarus sinuatus Say, Lernanthropus brevoortiae Rathbun, 

 and Clavellisa spinosa Wilson. 



The following have been listed by Linton (<§5: 440): Scolex polymorphus Dujardin, 

 a cestode, small and free in the intestine; cysts and blastocysts of Synbothrium on the 

 viscera; and the trematodes Dw/owzaw appendiculatum Rudolphi and T). vitellosum Linton; 

 later he added Dactylocotyle sp., and Distomum pyriforme Linton {86: 352). 



Hardcastle has reported a sporozoan parasite of the genus Eimeria for the testes 

 of specimens taken at Beaufort; he stated that a "study of over a hundred individuals 

 [Menhaden] showed an infection of nearly 50 per cent" (5^: 214). 



Diseases. No report of a specific disease has been found in the literature, but 

 there are records of many fish having become stranded along the shore. It has been 

 suggested that their enemies at times drive them ashore, but my observation is that the 

 fish make no special effort to flee from enemies. In fact, when caught in a net they 

 make little effort to escape. It seems more probable, therefore, that the stranded fish 

 died of a disease. An epidemic has indeed been reported (J2J: 742). 



Variations. Large fish generally are proportionately deeper than small ones, and 

 those from the southern part of the range are proportionately deeper than northern 

 ones. However, the variation in depth among fish from any one general region is great 

 enough to obscure any definite distinctions. Southern fish have a somewhat larger head 

 and longer fins (especially the pectoral) than those from the northern part of the range, 

 but the gap is fully bridged by examples from intermediate areas. Contrary to expecta- 

 tion, data at hand show that the vertebrae do not average fewer in southern specimens. 

 But further detailed studies are needed to determine the exact characteristics of popula- 

 tions inhabiting the different general sections of the coast; even now specimens from 

 the Gulf of Maine are too few in the collections at hand to determine their finer charac- 

 teristics. 



As shown in the Description, the number of gill rakers increases greatly with age, 

 with the principal increase occurring before the fish reach a length of about 100 mm 

 (4 in.). Also, the scales in small specimens have only irregular margins while those in 

 larger fish are pectinate. In using scales to differentiate species (their development in 

 all species being similar), it is necessary to compare scales from examples of about equal 

 size; and it is preferable to use large specimens, for in them the differences are most 

 pronounced. 



See Color for variations in color. 



Commercial Importance. These fish, though exceedingly valuable, are not used very 

 extensively as food by man, mainly because of their bony nature and oiliness. How- 

 ever, some find the flesh delicious, and those living along the coast, especially the 



