— 31 — APPENDIX Et HEINCKE 



the opportunity of fishing there at this time lor the mature cod; we have met with these 

 on our seasonal cruises, only in March 1903 and 1904, and always in small quantities only, 

 as also on the fishing grounds of Borkum Reef, Oyster Bank, Heligoland, Sylt inner 

 ground, Horns ßeef and southern Mud Bank. 



The biological picture, which we obtain of the cod in our region from the investig- 

 ations sketched above, is strikingly similar to that of the à2,h(Pl.linianda). The cod 

 appears here as a stationary fish, whose developmental stages from the Qgg 

 to the spawning fish are all passed through within the same region; to such 

 a degree, indeed, that all the stages are found intermingled at the most different places, 

 without anywhere or at any time, showing a graded distribution according to age and 

 depth. Only the larger and older specimens seem to make any migrations worth mention- 

 ing, as, in the summer they live more in the open sea, e. g. in the south-eastern parts of 

 the North Sea, whilst in winter — assuredly for the purpose of spawning — they frequent 

 the shallower parts of the region from the 40 m. landwards. The largest cod of 1 m. and 

 more in length and 10 and more years old, live furthest from laud apparently and in the 

 deepest part of the region. 



We are not yet able to show positive results concerning the migrations of the cod 

 by means of the marking and setting out of fish. 



The fully formed haddock. 



The smallest fully formed young haddoch taken by us, measured 24 to 26 mm. in pre- 

 served condition. We are unable to state, as yet, at what average length the transition 

 from the larvae to the adult form is completed. 



The occurrence and distribution of the fully formed haddock of the first year — of 

 the 0-group — shows an important and very striking difference from that of its two 

 nearest allies, the cod and the whiting (Gadus merlangus). We have hitherto taken 

 them only north of 55° N. L. and mostly far out to the north of 57°N.L. in 

 and over the great depths from 60 to 100 m. and more. We have captured but 

 one single specimen south of the Dogger Bank, on its south-eastern edge in the so-called 

 Clay Deep from 47 m. (middle of July, 1903), also once a single specimen on the southern 

 Mud Bank in the three-otterboards net (middle of July, 1904). 



The greatest quantities were found in the first half of July, 1904, north from the 

 Fladen ground on muddy ground at 134 m.; 2 hauls of our Heligoland trawl, of 20 minutes 

 in all, brought up here 237 small haddock of the 0-group from 3 to 10 cm. long, most of 

 them 6 and 7 cm. Large quantities (from 40 to 50 in one haul) were also taken, further 

 to the north of the first-named place in 106 m.; otherwise, we mostly obtained only 

 ] to 10 specimens in one haul with the ground-nets. It was remarkable, that we brought 

 up but very few young cod at the places, where we obtained many young haddock on the 

 ground , and conversely , where many cod of the 0-group were found , very few haddock 

 were taken. The former occurred chiefly on sandy, the latter on muddy ground. Another 

 remarkable difference in the occurrence of the 0-group of cod and haddock was also 

 observed; in our surface nets (three-otterboards net and Hjort's net,) we obtained the cod 

 very rarely, as already mentioned, and always only in some few specimens, where the had- 

 dock was often abundant. Our greatest catch of young fish with the three-otterboards 

 net was made on the slope of the Great Fisher Bank towards the Skager Kak over 



