REPRODUCTION AND BIOLOGY OF 



MATURE ATLANTIC -SCANDINAVIAN HERRING 



Regions and Conditions of Reproduction— 



The fact that herring spawn off the south-western coast of Norway was probably well-known 

 long before the investigations of Boek (35). Boek established that herring spawn in this particular 

 region on the slopes of the banks situated near the underwater "valleys" along which they approach 

 the shore . Spawning occurs at a depth of 70 meters . Most frequently the herring deposit eggs in 

 those areas where the floor is covered with large and small gravel. Boek succeeded in gatliering 

 compact lumps of fertilized eggs mixed with bottom material from these areas . 



RunnstrOm (65, 67), Sund (72, 76) and other Norwegian researchers have shown that spawn- 

 ing in these regions begins in the middle of February, continues throughout March and ends in 

 early April. The spawning grounds are located along the entire south-western coast of Norway, 

 from Cape Lindesnes in the south to Alesund in the north. 



The most important spawning grounds are south of Bergen, near Karmj^y and Boknfjord. 

 North from Alesund, we found herring larvae in early stages of development on Traena Bank, 

 located around 64° north latitude . Observations by Ruimstrtim (67) show that herring reproduce at 

 depths of 5-10 to 140 meters. It has been established that spawning is particularly Intensive at the 

 depth of 40-80 meters. 



According to the same author, percentages of herring eggs found on different kinds of bot- 

 tom in the region of the south-western coast of Norway were as follows: On rocky soil - 45.5% 

 (of the total amount of roe encoimtered), on seaweeds overgrowing the rocks - 7.7%, on stony 

 ground - 11.7%, on gravel - 7.7%, on sand - 1.8%, on shell rock - 24.9%, on soft bottom - 0.7%. 



LeGall (57) showed that herring spawn off the south-western coast of Norway at a water 

 temperature of 4-7°C and a salinity of 33-35. Runnstrflm pointed out that the greatest egg deposi- 

 tion was found along demarcation lines between the slightly less saline and relatively cold v/aters 

 of the surface layer (where the water temperature is usually below 4-4. 5°C and salinity less than 

 32-33) and the warm, highly saline Atlantic waters which usually lie at a depth of 40-50 meters 

 and more . 



1/ The study of the spawning grounds of the Atlantic sub-species of herring, Atlantic - 

 Scandinavian race in particular, involves certain difficulties in view of the fact 

 that these spawning grounds are located at considerable depths. Scientists have 

 not always, nor everywhere, succeeded in gathering roe from the bottom by means 

 of trawls or bottom -scrapers. The easiest and the most reliable method of locating 

 the herring spawning grounds consists of gathering early larval stages with nets 

 made of silk or some other fine mesh. The presence of a great number of these 

 larvae in the water considerably facilitates the task. Spawning grounds in the region 

 of Iceland, Faeroes and on the Lofoten shelf have been located with the help of the 

 above-mentioned method. Freshly swallowed roe that may be found in the guts of 

 haddock is a reliable index of spawning grounds . 



Establishment of spawning grounds on the basis of catches of mature fish, males 

 with liquid sexual products in particular, is a far less reliable method, since these 

 fish may be found at considerable distances from spawning grounds . 



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