36 Fishery Board for Scotland. 



measured only thirty feet. This apparatus has been very frequently used in the 

 ■ North Sea, much more so than in areas beyond the North Sea, yet the other five 

 records of small forms were made by means of this apparatus in the areas outside 

 the North Sea. It mav also be noted here that, whilst these bottom forms were 

 caught at 58° 44' N. ; 7° W., and 59° 4' N. ; 7° 4' W., post-larval stages, 15 to 17 mm. 

 long, were obtained at 59° 54' N. ; 7° 6' W., and 59° 36' N.; 7° W. In addition, 

 our knowledge of the distribution of bottom forms of under 200 mm. in length is 

 extremely scanty, although the Angler, on account of its peculiar shape, is specially 

 liable to capture in the ordinary trawl long before it reaches this size. Fulton, 

 who gives most information concerning these sizes, says that they are obviously 

 uncommon on bottoms suitable for trawling, otherwise they would be taken in 

 much greater numbers. This statemeiit is undoubtedly true for the North Sea, but 

 his suggestion, viz., that in the case of the Angler, a prolonged pelagic hab't is out 

 of the question much after the post-larval stage, was made before the elaborate 

 developmental changes, through which the post-larval stages pass, were known. 

 He therefore adds that the reason for the comparative scarcity of records of young 

 Anglers may be that they frequent rocky algse-covered ground, where they can 

 have shelter and suitable food. According to this view, the young Angler, up to 

 a size of about 200 mm., might be considered as a shore-fish. But small forms of 

 Lophhis piscatorius are conspicuous by their absence from all lists of shore-fishes. 

 Fulton (1902), however, in the same Report, states that the proportion of small 

 Anglers (that is, of over 200 mm, in length) on the deep-water grounds appears to 

 be higher than on the inshore trawling grounds, and that the higher proportion 

 in the deep water may indicate the comparative absence of shelter, and it shows in 

 all probability that spawning and the developmental changes may take place far 

 from land. Biit shelter in these deeper water grounds from the operations of the 

 commercial trawl is no more possible for the somewhat smaller bottom forms than 

 for the larger ones. 



All the facts concerning the occurrence of the floating sheets of spawn and the 

 larval and post-larval stages may nov/ be taken together. The absence, or com- 

 parative scarcity, of these forms from the records for the northern North Sea may 

 be very simply described by the hyj)othesis that they do not occur there, or are 

 there m very small numbers. In other words, although Anglers may spawn in 

 small numbers in the northern North Sea, this area is not the main spawning area, 

 and the Angler does not appear there in numbers, until it has reached some consider- 

 able size. 



The records of the sheets of floating spawn are of especial interest in this re- 

 lation. If the records of the capture of these sheets of spawn are examined with 

 care, it will be found that in all cases, except the one already described, the embryos 

 in the eggs were already very far advanced in development. These sheets of spawn 

 float passively during the whole period of development of the embryos in the eggs, 

 and perhaps for some time longer, and are drifted with the prevailing currents 

 from the areas in which they were originally spawned. They are objects analogous 

 to the floating drift-bottles which Fulton experimented with to test the direction 

 and rate of flow of the surface waters in the North Sea. He has shown very con- 

 clusively that there is, at all seasons of the year, a fairly constant slow circulation 

 of the surface water in the North Sea, Atlantic water entering round the North of 

 Scotland and between the Orkneys and Shetland s, and passing southwards along 

 the east coasts of Scotland and England, as far as the neighbourhood of the Wash, 

 then in an E.N.E. direction towards the coast of Denmark, and then northerly 

 along the Danish coast. 



The sheets of spawn found along the east coast were spawned, if not without 

 the North Sea, at least in an area in the North Sea further north than the locality 

 in which they were fouud. Ehrenbaum's record of a sheet of spawn in the Skagerrak 

 in July does not conflict with this statement, for, if one may judge from his de- 

 scription of the spawn of the Angler, it is evident he had never seen it when recently 

 spawned. 



It must be-borne in mind that, if the spawning area of a species is to be deduced 

 from the occurrence of the eggs, larvae and post-larvee of a species, the proximity, 

 of the true spawning area will depend on the time it takes for the species to pass 

 through these stages of development, and the strength of the prevailing currents. 



