Remarks on some Plankton Forms. 



Pisces. 



Egg's and Larvae. 



hi Marrli ami A|iiil is'.iCi. lisli spawn was reg-ularly , found 

 ill the plankton on tin- 1-ot'oton liaiiks. That the «rreater part of 

 this hclon-vd to cod was. t considor. niKincstionablo. In 1897, fish 

 spawn was also noticed from '' ■• to 'i 'l. In 1899, a con.siderable 

 (piantity of tisli eggs was to be seen in the sea at Vest Lofoten, 

 on Mai'ch 20tli and on April 1st a mass of fish eggs was seen on 

 the East I^ofoten banks. Also in 1900. fish spawn was noticed in 

 the latter half of the month of March. 



Tartienlarly in 1897 several samples containing- spawn were 

 examined. Various sizes were found, right up to a diameter of 

 •2..-> mm.; hut the diameter of the majority was about 1.3 mm., which 

 means that most of it was cod spawn. We also got a few cod 

 larva' in the tow net. as for instance on 'A 1B97 on the fishing- 

 ground at Keine. The characteristic pigment bands left no room 

 for doubt that we really had caught larvæ of cod — their length 

 was about .3.5 mm. It was quite remarkable how seldom one came 

 upon a sterile egg. One cannot, however, because of this fact con- 

 clude that fertilization was carried out in a particularly effective way, 

 indeed one can hardly exercise any control over this in the open 

 sea. For cod spaAvn is doubtless subject to the same law as for 

 instance, salmon spawn, which dies pretty quickly if it has not been 

 fertilized. (Some cod eggs were put into a glass of sea -w^ater, 

 and it was seen that the eggs fell to the bottom as soon as they 

 died. In the open sea also, the dead eggs without doubt sink to 

 the bottom, so that it is not possible to gain a correct idea of the 

 effectiveness of fertilization by counting the eggs capable of devel- 

 opment which are found in the water. 



Respecting the spawning of the skrei {Gaihis mllarias L.) 

 reference should be made to Hjokt's book „Fiskeri og Hvalfangst" 

 (Fishery and AMiale Catchini;). page 37 ei scq. 



Deeapoda. 

 Pasiphæa tarda, Keoyer. 

 By tow-nettiiiL:-. I have only obtained young individuals of this 

 species, (^uite rarely, single specimens have been found. 

 Thus 'A 1899. Ofoten I, 300—3.50 mm., 1 specimen, length 27 mm.=) 

 ■■'/\i 1899. Tys Fiord I, 200—300 m., 1 specimen, length 26mm. 

 74 1900. Skjerstad Fiord V, 0—420 m., 1 specimen, length 



33 mm. 

 =-'^,',1 1902. The By Fiord, Bergen, 2.50—1.50 m., 1 specimen, 



length 12 mm. 

 I made the following notes about the specimen from Ofoten: — 

 Body, quite transparent, brown eyes and a reddish tail appendix. 

 In „Bidi-ag til Kundskab om Christiania Fjordens Fauna" (Con- 

 tribution to a Knowledge of the Fauna in The Kristiania Fiord) 

 M. iSars describes the young of this species (p. 56 — 63, fig. 81 — 90). 

 These were taken near Skroven in Lofoten by G. O. S.^rs and the 

 smallest was 10 mm. in length. 



1) Cf. NoBDGAARD, „Contril)uti<)ii to tlie Study of Hydrography and Biology 

 on the Coast of Norway". Tables 2, 4 a. 4 b. 



^ Measured from the point of the rostrum to tlie tip of the tail. 



As far as 1 can see, (1. O. Saks was the fir.st to observe the 

 pelagic habits of this species. In ,,Crustacea II" from the Norw. 

 North Atlantic Expedition (1876—78) he .says (page 11): „Mean- 

 while, though the specimens in (luestion all came up in the trawl 

 from very considerable depths, reaching 17()0 fathoms, yet the animal 

 may, considering its obviously pelagic habits, have entered the trawl 

 in some of the higher strata, during the upward passage of the 

 apparatus.'" Tlic cxiicdition above mentioned also took its .speci- 

 mens of I'asqilian with a trawl at the stations 33, 213 and 295. 

 Of these stations 33 is in the southern part of the North Ocean, 

 213 about halfway between Jan Mayen and Norway and 295 (Lat. 

 71" 59' N., Long 11° 40' E.) is somewhat further north and east. 

 It is easier now with the improved apparatus for pelagic fishing to 

 catch the animal. It appeared in considerable numbers in the North 

 Ocean'). With regard to the distribution of this species in the fiords of 

 Norway, it may be mentioned that it has been found from The 

 Kiistiania Fiord up to Lofoten, but its distribution is now^ known to 

 be extended over a larger area. In April 1899, I took specimens 

 with a trawd in The Malang Fiord from a depth of 380 m. There is 

 no doubt that it is rather common in certain other fiords. For in- 

 stance, I have often seen it in the stomach of Macrurus rupestris, 

 Spinax niger and Gadus rirens fi-om The Herlø Fiord near Bergen. 

 The young individuals of this species mentioned as being taken in 

 The Ofot, Tys and Skjer-stad Fiords were all caught in the months 

 February — April. Althoug-h it is not stated, it is likely that G. O. 

 Sars took the yomiL' staL'-es on which M. Sars has based his de- 

 scription, also siiiihtiiii,' ihiiiiij the early spring months, for G. 0. 

 Sars was, in the \ rars nitiitiouiMl. making winter researches in Lofoten. 



One would be inclined to think that about the middle of the 

 winter is the time of propagation for this species. It is, however, 

 reasonable to suppose that the propagation stretches over a period 

 of several months. In the stomach of Spinax niger from The Herlo 

 Fiord, I found 'Vt 1897 a female with large eggs attached. 



Another Pasiphæa female with eggs was found in the stomach 

 of a Gadm virens from The Herlø Fiord 'Ve 1902. 



Kroter based his original description on specimens from Green- 

 land, and the species is also said to be found on the east coast 

 of North America. 



Sehizopoda. 



Nyctiphanes rwrvegica, M. Sars. 



As is the case with Pasiphæa tarda, this is a plankton form, 

 which it is difficult to catch in small tow-nets. A large number 

 of my specimens have been taken in a trawl. Here is a list of 

 the various places in Avhich they have been found. 

 1% 1897. Sunderø (Vesteraalen), several specimens in the stomach 



of Gadus rirens. 

 "A 1899. Helle (Ostnes Fiord), 0—120 m. 1 jun. (tow-net). 

 'Vo — Raftsund 0-275 m. rr — 



"A — Følstad, (Ostnes Fd.), -135 m. rr — 



>) Cf. H.70KT, ,,Fiskeri 



valfangst" (Fishery and Whale Catching), p. 



