APPENDIX E; HEINCKE _ 38 _ 



same spots, and intermingled with one another, within the region investigated. The 

 whiting has this in common with the dab especially, that it is the most abundant 

 species of its genus in the North Sea. A specific characteristic of the whiting, 

 which distinguishes it, especially from the cod but also from most other gadoids, is the 

 strong tendency towards a pelagic habit of life during the first year, which, 

 also, it never seems to give up entirely in later years. 



8. Concluding remarks 



We have still to describe a large number of observations, made in the region nnder 

 our survey, concerning a number of other food-fishes, above all the turbot, sole, witch 

 [PI. cynoglossus) , sprat and herring, but these observations have not yet been so far 

 worked up, as to enable us to make a comprehensive report regarding them. 



If we summarise the results of our investigations in the German portion of the North 

 Sea, described briefly in preceding pages, it appears, that many important facts concerning 

 the distribution of the food-fishes could already be determined in the two years since the 

 beginning of our investigations, and that a view has been gained of the right course to 

 be taken, in order to advance. It is also clear, however, that very great gaps have yet to 

 be filled up in our region by new and continued observations, in order to attain the end 

 placed before the international investigations. As regards the earliest developmental stages, 

 the eggs and larvse of our food-fishes, more frequent observations must above all be made 

 in the months of January to March, and especially in February, in the northern North 

 Sea; further, special attention must be paid to the, as yet, but little known eggs and larvae 

 of certain gadoids, e.g. of the saithe (G.virens), pollack {G. pollachius) and of the pouts 

 {G. luscus, G.minutus nnd G. Esmarki). As regards the young fish in their first year, 

 similar investigations are desirable in May and June, especially in the northern North Sea, 

 in order to know, more accurately, the transitional stages between the larvae and earliest 

 bottom-forms, even for the haddock and cod, and their occurence as regards the especially latter 

 species ; these are specially necessary at such parts of the sea-bottom, where the ordinary 

 fishing apparatus cannot as yet be used. With respect to the occurrence, migrations and 

 spawning of the older stages of the food-fishes, the following investigations have still to 

 be made. Kesearch-cruises must be undertaken in the winter months, in order to deter- 

 mine, for the North Sea, the regions and periods at which great collections of spawning 

 plaice, cod and haddock occur. The number of marked plaice set out must be considerably 

 increased and similar experiments have to be made with the cod and haddock. 



The method of determining the age of the food-fishes has to be extended and applied 

 to more species, and at the same time, their rate of growth must be tested experimentally. 

 Lastly, more exact investigations are to be made regarding the proportion of the sexes, 

 and the fertility of the fishes and also, regarding the various stages in the maturation of 

 the sexual products. 



