[23] EGGS OF THE PLAICE, FLOUNDER, AND COD. 449" 



combined cause the distribution of the eggs over a large are;i. The 

 occurrence in coast waters of water-areas, belonging according to their 

 character and fauna to the high seas, as has been observed for a 

 long time in the Gulf of Kaples, will intluence the distribution of the 

 eggs. The mechanism of the cnrrents caused thereby has so far, how- 

 ever, not yet been made the subject of scientific investigation. 



On the other hand, however, currents may also impede the even dis- 

 tribution of the eggs, partly by causing stoppages and whirlpools in 

 the water, but principally by changing the specific gravity of the water. 

 In my opinion the very rare occurrence of codfish and plaice eggs in the 

 harbor and the Bay of Kiel must be explained, at least in part, by the 

 circumstance that the fresh water which flows into the harbor from the 

 river Schwentiue and other streams hinders the entrance of the eggs. 

 By such currents and the water losing some of its saltness the distri- 

 bution of the eggs at the bottom may became very irregular. My ob- 

 servations, however, did not clear up this question. It is also i^robable 

 that during storms the bottom of the shallow Baltic is sufficiently stirred 

 up to scatter the eggs lying at the bottom. 



My observations, however, have proved, at least made, it highly proba- 

 ble that eggs are scattered in the Baltic over a large area. Even far out 

 in the Baltic I found numerous eggs, viz, 85 per square meter of the 

 surface, and only the entrance of fresh water from the north prevented 

 further observations. The evenness of the distribution has also be- 

 come more probable by my having found 32 and 20.2 eggs per square 

 meter at intervals of one half mile (German) in a perfectly calm sea. I 

 must also state that I always found in these masses of eggs not only 

 different kinds of eggs, but also eggs in many different stages of devel- 

 opment. It is hardly probable that the fish from which these eggs 

 came had spawned all over the Baltic, the different species mingling 

 with each other. 



However this may be, the quantitative examination of this subject 

 (perhaps by fishing along the sides of a triangular area) is of great in- 

 terest in itself, for only thereby we can arrive at an approximately cor- 

 rect knowledge of the whereabouts and the fate of the eggs, and of the 

 dangers which threaten them at this stage of their development. It 

 will, moreover, be a great advantage, if our investigations as to the oc- 

 currence of different kinds of fish can be made without regard to the 

 statements of fishermen and data gathered during the fisheries. The 

 latter are occasionally very one-sided. 



As regards the idea from which I started — to obtain an approximate 

 estimate as to the quantity of certain kinds of fish found within cer- 

 tain areas of water — the reader will, after all that has been said, be better 

 able to appreciate the difficulties connected with these observations. 



It might be possible to obtain, by numerous counts, an approximate 

 estimate of the number of eggs per kilogram of spawning fish; but 

 then the question arises, How many of these eggs are actually impreg- 

 S. Mis. 10 29 



