PROPAGATION AND PROTECTION OF THE RHINE SALMON. 829 



Holland perhaps a few thousand more salmon were taken. Then comes the 

 German part of the river, and finally that part where the river forms the boundary 

 between Germany (Baden) and Switzerland and where important salmon fish- 

 eries are found; but as to the fish taken in the German and Swiss parts of the 

 Rhine no reliable figures are published. Altogether an estimate of 65,000 sal- 

 mon as taken in the Rhine during the year 1907 remains probably under the 

 actual production. That year was by no means an exceptionally good one — it 

 was slightly better only than the eight preceding years. A catch of 65,000 

 salmon in such a year gives us the right to say, I think, that, be its productivity 

 no more so great as it was before, "Old Father Rhine" still is entitled to be 

 called an important salmon river. 



Now, it is my conviction, and I wish to conclude my little lecture by saying, 

 that the Rhine to a very large extent owes to salmon culture the conservation 

 of this production. The fact that the same river had more salmon before arti- 

 ficial propagation was begun does not disturb that conviction ; that was at a time 

 when natural propagation was still flourishing. Since the latter in the Rhine 

 nearly quite belongs to history, only one way to keep up the stock remains, and 

 that is by artificial propagation practiced in the most normal, most natural way. 



DISCUSSION. 



Prof. E. E. Prince. There is just one question I would like to ask Doctor Hoek, 

 and that is as to the spawned salmon or kelts. How and when are those observed 

 migrating, and what is the view in regard to their suggested destructiveness in salmon 

 rivers, owing to their predacity? 



Doctor HoEK. Mr. President, I thank you very much for the opportunity of 

 telling you. 



Kelts return to the sea every year, but not in very large numbers. It is true that 

 our fishing is so organized that we catch the fish coming from the sea and not so well 

 the fish coming down; yet at least some of these fish do not come down so very fast, 

 but remain in a certain part of the river for some time, moving perhaps with the tide. 

 We take some kelts every year. Doubtless it will be interesting to you, in the first 

 place, to hear that most of these kelts are taken on the Rhine in Holland in the months 

 of March and April, and not many earlier; in the second place that the sexes are rep- 

 resented in the kelts about as in the ascending fish, but that the males descend earlier 

 than the females; and, in the third place (which I think is most interesting), that very 

 large kelts have never been taken — the largest kelts we know are of the type of the 

 smaller, so-called summer salmon (length 75 to 93 cm.), and do not belong to the big 

 summer salmon or winter salmon. It remains only to tell you that we made some 

 observations on the food found in the stomachs of the kelts, and that it was found to be 

 indeed a very poor food. From what I have seen on the Rhine I must conclude; that 

 they are not accustomed to taking food on that river. 



