296 BRITISH FRESH-WATER FISHES 



has been well established, we are far from being complete 

 masters of the eel mystery. The elvers ascend the streams 

 all round our coasts, penetrating to the remotest lakes and 

 the most secluded pools, frequenting the channels of the 

 greatest rivers as well as the wayside ditch. Wherever a 

 living is to be made under water, there you may reckon 

 upon good store of eels, but of their rate of growth nothing 

 is known. Neither has it been ascertained how long they 

 remain in fresh water ; only this is certain, that a time comes 

 when an exodus takes place seaward. Not a migration of the 

 whole eel population, as is the case with salmon and smelts; 

 only of those individuals which begin to feel the sexual 

 impulse. In the autumn months these begin dropping down 

 the rivers, when they are taken in large numbers by ' c eel- 

 bucks" wicker baskets fashioned inside like a mouse-trap 

 and set in a wooden framework across the stream. 



The question has often been discussed whether eels ever 

 return to the river after spawning in the sea. Probably they 

 do not, for there is no trustworthy evidence to that effect, 

 and the acumen of fishermen may generally be trusted to 

 detect the seasonal movements of their game. It seems most 

 likely that eels remain in fresh water for an indefinite number 

 of seasons, till the generative impulse makes itself felt, when 

 they at once go to the sea. There the development of the 

 organs of reproduction is very rapid, and the exhaustion 

 after the act of reproduction so great that both sexes die, 

 having fulfilled the primary law increase and multiply. The 

 number of eggs in the ovary of a female eel thirty-two inches 

 long has been computed at ten millions seven hundred thousand. 



In the complete absence of all evidence to the contrary, 

 it may be assumed that it is only in salt water that eels can 

 spawn. This seemed to be hard to reconcile with the fact 

 that throughout the long period, sixty or seventy years, when 

 the Thames was closed by pollution to fish from the sea. 

 eels continued abundant in that river above the tideway. So 



