BREEDING PLACES OF THE EEL SCHMIDT 



311 



Fig. 15. — American Eel (Angiiilla rostrata) 



Distribution of larviB (dotted area) and of adults (black strip along the coasts where 

 the species occurs). 



The curves sliow limits of occurrence ; i. e., larv'se less than 15 mm. have only been 

 found inside the 15-mm. curve, etc. ; the outermost curve denotes limit of occurrence of 

 unmetamorphosed larv® (ul). 



How does the distribution of the adult stages of Anguilla rostrata agree with the 

 distribution of the larva>? 



Many years ago (Johs. Schmidt, 1. c, 1909, p. 8) I tried to find a numerical 

 expression for the density of eels in the United States, dividing the States into three 

 regions: (1) Atlantic region (rivers draining Into the Atlantic) ; (2) Gulf region (riv- 

 ers draining into the Gulf of Mexico) ; (3) Pacific region (rivers draining into the Pacific). 



Setting the product of the eel fisheries in the States in connection with these subdivi- 

 sions of the region, we find that of the total product about 98 per cent comes from the 

 Atlantic region, especially the northern States (North Carolina and northwards) and 

 only about 2 per cent from the Gulf region (nothing from the Pacific) (cf. chart above). 



This difference is so striking that we may conclude therefrom that there is a much 

 greater run of elvers in the Atlantic region than in Ihe Gulf region. 



A glance at the chart above shows that the center of production for the larvas of 

 Anguilla rostrata is situated north of the West Indies (inside the lo-mm. curve) and 

 that the larvae during their increase in size spread out to the north and only to a smaller 

 extent to the south. On our cruises we found masses of larvte north of the West Indies 

 and in the Gulf Stream region off Atlantic coasts of the States (cf. fig. 17;, but com- 

 paratively very few south of the West Indies in the Caribbean Sea and in the Gulf of 

 Mexico. 



There is thus an excellent agreement between the density of eels in the United States 

 and the results of our investigations regarding the breeding grounds of Anguilla rostrata 

 and the direction of migration of its larvae. 



