THE EGGS AND LARVAE OF THE ANGLER [LOPHIUS 

 PISCATORIUS L.) IN SCOTTISH WATERS. 



INTRODUCTION. 



The Angler {LopMus piscatorius), with its bizarre form and strange adaptations 

 to mode of life, has always attracted much attention. In recent years, it has 

 become increasingly important commercially, and the species, regularly brought 

 to market, now contributes its share to the food supply of the nation. The Angler 

 often grows to a very large size, sometimes exceeding 5 feet in length. The 

 very large, broad and depressed head of grotesque appearance is of no commercial 

 value, and the practice has grown up of landing only the tails on the markets, 

 and these find a ready sale. 



Many contributions to our knowledge of the life-history of this strange species 

 have been made. In spite of the wealth of fact, however, many details of the 

 life-history still remain obscure, and, in particular, little is known definitely regarding 

 the chief spawning-places and the distribution of the larval, post-larval, and small 

 bottom-forms. 



The first important contribution to a knowledge of the spawning and of the 

 young forms was made by Agassiz in 1882. In that year, he described the eggs 

 and larvae from specimens obtained in the Atlantic off the American coast. In 

 1891, Prince gave somewhat similar descriptions of forms from Scottish waters. 

 Although both these authors deal very fully with the appearance of the eggs and 

 the larvae until the absorption of the yolk, there is little reference to the later 

 stages. (Agassiz describes one post-larval stage of about 30 mm. in length.) In- 

 deed, there was almost an entire absence of definite information regarding the 

 later post-larval stages until 1911, when Stiasny gave a very detailed description 

 of forms found by him in the Gulf of Trieste. In this publication we have, until 

 now, the only detailed reference to the capture of the later post-larval stages. On 

 the other hand, there are no specific references to the spawning-places of the Angler. 

 Further, information regarding the distribution of small bottom-forms is very 

 scanty. Dr. Fulton (1902) has dealt most fully with this aspect of the problem, 

 and he points out that small Anglers are very rarely met with in the North Sea 

 under a size of 6 inches, although adults are by no means rare within the area. 



In brief, our knowledge of the early life-history and the developmental changes 

 through which the young Anglers pass is built up from information derived from 

 very widely separated areas. Yet, when one thinks of the comparative frequency 

 of adult Anglers over a very wide area, and the striking appearance of the floating 

 masses of spawn, and the post-larval forms, one may well feel astonished that 

 complete information regarding the life-history has not been obtained even from 

 restricted areas where the spawn and adults are known to occur. 



In the jjresent communication a detailed description is given of the occurrence 

 and developmental changes of the Angler in Scottish waters, and, in addition, 

 an attempt is made, from a consideration of all the facts known about the distri- 

 bution of the adults, and the younger stages, to bring the detached facts from the 

 different areas into harmony. 



The characteristic appearance of the ovaries and the ova just before and after 

 maturation, as can be very easily verified by a microscopic examination of the 

 parts in the adult, has been very minutely described by Dr. Fulton (1897, p. 125). 

 The following is that author's description of some of the points which have a bearing 

 on the problem under consideration : — " The ovaries are confluent, and form a 

 single, long, flattened tube or band whose dimensions vary with the size of the 

 fish and the season of the year. In a specimen with almost mature eggs, caught 

 on 11th February, the ovaries measured a little over 29 feet in length, the greatest 

 breadth was 13| inches, and the thickness was only 4 millimetres. It formed a 

 long, flat, semi-transparent band, soft and easily ruptured. The ovaries form a 

 continuous tube, the oviduct, which is thick-walled and narrow— admitting a finger 

 with difliculty— opens into it at its middle, at the junction of the ovigerous and 

 non-ovigerous sides. The ovigerous tissue is limited to one side of the tube, the 

 opposite wall of the ovary, a thin, delicate, translucent membrane, being closely 



M&GUd Wt5799/S.O.P. 80 10-20 300 G. 2 



