THE FISHES OF THE IRISH SEA. 55 



Menai Straits. The witch spawns from May to July. The female produces from 500,000 to 

 800,000 ova, which measure 1*15 to z'lg mm. in diameter, and hatch out in about a week. 

 We have made use of this species for some experiments in fish-hatching- at the Port Erin 

 Biological Station. 



SOLEA VULGARIS, Quen. Sole. 



(Day's British Fishes, vol. II., p. 39, PI. CVI.) 

 (Fish. Mus., Zool. Dep., Univ. Coll., Liverpool.) 



The true, or black, Sole and its immediate allies are distinguished from other flat-fish 

 by the narrow, elongated, oval body, the rounded snout with the mouth a little way behind, and 

 the curved jaws. 



The true Sole ranges from Scandinavian seas to the Mediterranean, and is found 

 around our coast generally, but is commoner in the South than in Scotland. It is a shallow- 

 water fish. It is of frequent occurrence throughout our district, and forms one of our most 

 important fisheries. A well-grown sole is usually from 15 to 18 inches long. The smallest 

 ripe female we have found was n| inches, and the smallest ripe male 10 inches. The Sole 

 spawns from March to June, and produces 100,000 ova. The egg is about 1*5 mm. in 

 diameter, and is distinguished from other flat-fish eggs by having many small oil globules 

 scattered in patches over the surface of the food-yolk. The larva hatches out in about 10 

 days. We have frequently had the female sole spawning in captivity in our tanks at the Piel 

 Hatchery, but have not yet succeeded in getting the eggs fertilised by the male. 



The sole fishery of the Lancashire and Western Sea Fishery District is very valuable. 

 The Board of Trade estimates it at ^28,900 for last year, 1900. Statistics are, however, not 

 taken at all centres where fish are landed, and the Board of Trade draws attention to the fact 

 that this value only represents the fish when first landed direct from the fishing grounds, and 

 points out that at a later stage of the industry, with the cost of carriage, etc., added, it is 

 much enhanced. 



The sole is captured by the use of the trawl net. The sole grounds in and adjacent 

 to the district are numerous, and extend from the northern to the southern limits of the 

 district. Soles are taken all the year round ; in the warmer months they come near the coast, 

 and frequent our estuaries and bays ; during the colder months they go offshore into deeper 

 water. They are occasionally taken in drag nets close to the shore, as at Port Erin, in 

 the Isle of Man. 



The spawning grounds lie at considerable distances from the shore. The sole has 

 been taken in increasing numbers during the last few years. Bye-laws for the protection 

 of the small sole have been in force for some years, but it is difficult, with any degree of 

 accuracy, to attribute the increase to this, or in fact to any particular cause ; it may, 

 however, reasonably be contended, especially as the increase appears to have been gradual, 

 that the bye-laws have had some beneficial effect. The size of mesh formerly used in 

 trawl nets for the capture of soles was four inches, that is, one inch from knot to knot : 

 this was increased to six inches or one and a half inches from knot to knot, which allows 

 large numbers of small soles to escape. There are also closed grounds in a certain part 

 of the district, and other regulations for the protection of small soles, and lately deep-sea 

 trawlers have used the larger mesh, whether fishing inside or outside the district. 



