_ 35 — APPENDIX E: HEINCKE 



any found with almost ripe or quite ripe sexual products. Apart from these, all those 

 taken in autumn were in various stages of-ripeness, those taken in the spring were all spent. 



We have several times caught medium and large haddock on our June and July 

 cruises ; so far as their sexual products were examined, they were all spent or — in July • — 

 in process of developing new sexual products for the ensuing spawning period. 



We may therefore conclude with considerable certainty, that the mature haddock 

 spawn only exceptionally in the southern North Sea, but that, they not only occur there 

 in the last months of the year before the spawning time, often in great quantities, but also 

 return after the completion of spawning, often in very large swarms. 



We can thus recognize distinct migrations from and to the spawning and 

 feeding regions; and these migrations extend at times over very great distances. 

 Positive observations on the wanderings of the haddock, by means of marking and setting 

 out fish, have not yet been made by us. 



The picture, which the above investigations present to us regarding 

 the biology of the haddock, is essentially different from that of the cod. 

 The haddock is distinctly a migratory fish. It is born in the northern, deeper 

 parts of the North Sea, in greatest quantities on both sides of the 100 m. line, and it 

 always passes here the first and, with few exceptions, also the second year of its life. 

 It is only from the beginning of the third year, but mostly only in the fourth, that it 

 undertakes further migrations; thus, the haddock come to frequent the shallower regions 

 in the southern North Sea, in seeking for the feeding places there. When they are 

 becoming ripe, they return again to the northern North Sea in the course of the winter, 

 in order to spawn there (from January to April). On the completion of spawning, they 

 migrate again to the south to the feeding places — and it appears, as if this to and fro 

 migration were repeated regularly each year. 



7. Tlie WMting (Gadus merlangns) 



The eggs and larvae of this species may be regarded as rightly determined for the 

 most part, although, in many points of the region investigated, especially in the May hauls 

 of the northern part of the North Sea, confusion with other gadoid eggs of the pollack — 

 poor cod groups (pollachius-minutus) is not impossible; the eggs and larva; of these groups 

 are insufficiently known, but are probably very like those of the whiting. 



In the quantitative hauls of March, 2000 eggs and 257 larvae were taken altogether. 

 By far the greatest quantities, from 100 to over 4U0 eggs and larvœ per square meter, 

 were taken in the centre of the south border of the Dogger, in the so-called Clay Deep, 

 where great masses of the eggs of cod and dab were also found. Apart from these, about 

 130 eggs and larvae per square meter were taken 40 miles N. W. from Heligoland in over 

 40 m. depths, of which the great majority (-/s) were larvae. Both stations seemed spawn- 

 ing regions, as the eggs were taken but sparingly in the intervening regions. 



The quantities of eggs taken at all other parts of the region investigated were 

 smaller, although they never quite failed in the south-eastern North Sea. As with the cod 

 eggs, they were very rare or were quite absent in the immediate neighbourhood of the 

 coast. North from the Dogger and from Horns Reef, the whiting eggs were met with only 

 in small quantities: their number was also very small on the Great Fisher Bank and in 

 the Skager Rak. They were absent at the Skaw. 



5" 



