31 



oiic or hvo yciivfs old. whilo tlie older oiies eniigrute to deeper plaees; in 

 otiier waterfi tlioro arc il wart- races tliat lioc-omc adnlt at a jiroportioiially 

 small size. 



It was clear to rae lieforeiinm!, liowever, tliat tliese two circumstaiices 

 conld Pcarcely be tlie main canse of the ditferent si/.es ot' tlie eels; for all sizes, 

 tn the very largest, are t'ound in l'resli water a« well as in salt water, and at 

 certain seasons very large cels are fouud on shallow water near the shore. 

 This very faet that the eel is independent of the salinity, made it im]irohable 

 that strongly marked dwarf-races of this fish would be found in onr seas, and 

 u direet examination of Uiis (|nestion gave also aiiotlier explanation of the 

 ]ihenomenon. The male eels were found to he so rai-e in the Lesser Bclt that 

 only "27 " „ of tiie males were eaiight there in the Hrst dark of the mooii 

 which generally gives most male eels there, as at other piaces, while I got 

 94 % in Roskildefjord in the first dark aud Hf) «/,, in the last darks; in 

 these latter darks, into the bargain, there were not Ity far caught so manj- eels 

 as in tlie former, so that the male eels, from this reasou also, play a still more 

 dominant i^art here. As the males, on tm average, do not weigh more than 

 c. ' 4 11>. a piece, wliile the females, as a rule, weigh •' , — 1 Ib. and more, it 

 will easily be miderstood fhnl the nverar/e size hemmes smaller ichere the males 

 are inrmerous, than ahere there is bat a little numher of them. The nnmerieal rela- 

 linn hetween the se.res is the main canse of the varimis average sizes of the silrer 

 eels in Diir iraters. for a romparison hetween the eels of either ser from flitferent 

 a-a ters does not shoir siich a differenee in size: c. 1<S indies is evervwhere the 

 muximum size of tlie males, aud very large females are found in all seas and 

 fresli waters, thougli certainly not in equally great numbers everywhere. In 

 (»ertain smaller brackisb waters, to be sure, it seems that some few eels, both 

 males and females, eau become silver eels with a total length which is some- 

 what smaller than that which is the minimmn in more open waters; tliis, 

 however. seems but slightly to affect the average size. 



To get the exact raeasures here is very difficult, as the fishermeu at the 

 various piaces use meshes of very different widths; aud as the Biologicai Sta- 

 tiou, OU account of the .shortness of the fishing-seasou, as a rule is unable to 

 examine the silver eels with its own fishing-tackle at more plaees than one in 

 the year, it will last some time before it can get more considerable materials 

 collected, by its own fisherv, from all parts of the country. 



From this reason I shall not now enter more closely into this matter, 

 but only mention that the uumerical relation between the sexes differs 

 very unich aniong the yelhn\- eels also, and that it, to a very high 



