of the Fishery Board for Scotland. 



487 



of the Marine Biological Association's Laboratory at Plymouth ; Mr Ernest 

 W. L. Holt ; Mr Olsen, Secretary of the Grimsby Marine Fisheries Society ; 

 and Mr J. Wrench Towse, the Honorary Secretary to the National Sea 

 Fisheries Protection Association. 



I. UNITED KINGDOM. 



The numbers of the Journal of the Marine Biological Association, 

 which have been issued since the last Annual Report appeared, contain 

 several papers dealing with fisheries. Among these, those of Mr Ernest 

 W. L. Holt are of special interest, inasmuch as they are concerned with 

 important practical questions. In the first* Mr Holt gives the results of 

 his investigations at Grimsby on the relation of size to sexual maturity in 

 pleuronectids, and on the destruction of immature fish in the North Sea. 

 He describes the characteristics of the ovary in flat-fish which serve to dis- 

 tinguish fish which have spawned from those which have never spawned, 

 and states that in the halibut, long rough dab, turbot, brill, megrim, 

 plaice, flounder, and common dab, ' when retained ova are not present to 

 ' place the matter at once beyond doubt, a spent can always be distin- 

 ' guished from an immature ovary by the wide flaccid anterior region, by 

 ' the greater length of the posterior process, and by the loose manner in 

 ' which the latter is lodged in the cavity alongside of the haemal spines.' 

 The common sole, lemon sole, and witch or pole dab present more diffi- 

 culty. 



In dealing with the limits of size in relation to maturity, Mr Holt gives 

 the following as representing the average sizes at which the female spawns 

 for the first time in the North Sea : — turbot 18 inches, brill 15 inches, 

 common sole 12 inches, plaice 17 inches, lemon sole 12 inches, halibut 

 (provisional) 36 inches, common dab 7 inches. The male turbot and 

 brill seem to become mature at about 12 to 15 inches. A male plaice 

 only 6 inches in length was found to be mature, but this Mr Holt regards 

 as probably altogether exceptional; and a female was ripe at 13 inches, 

 and several others at 15 inches. In the common sole the male reaches 

 maturity usually when about 10 inches long, in one case when only 8 

 inches, and in several others at 9 inches. The smallest ripe female was 

 10 J inches. The spawning period of the sole extends from the end of 

 April to the beginning of August, but is most marked in May and June. 

 It is pointed out that spent females begin to appear in the Humber at the 

 beginning of J uly, and continue to abound during August and September. 

 The smallest ripe male lemon sole which Mr Holt obtained was 6 inches 

 long, and the smallest ripe female 10 inches. In another paper on the 

 subjectf Mr Holt gives similar details of his investigations of cod and 

 haddock. The size limit he provisionally assigns to the female cod is 

 25 inches; the smallest ripe female was 26 J inches, and the smallest rips 

 male 22 inches. The provisional size limit applied to the haddock is 13 

 inches ; the smallest ripe female was 15 inches (but one at 11 inches was 

 nearly mature), the male becomes mature at about 11 inches. In both 

 the papers referred to, Mr Holt treats fully the question of the capture 

 and destruction of immature fish, and indicates the enormous numbers 

 of young flat-fish destroyed by the beam-trawl. In the five months, April 

 to August 1892, 10,119 boxes of small plaice (ranging from 7 to 13 and 

 rarely to 15 inches) were landed by beam-trawlers at Grimsby alone ; and 



* Journal, vol. ii.. No. 4, p. 363. 

 t Journal, vol. iii., No. 1, p. 78, 1893. 



