FISHES 46. Five-bearded Rockling. Onus mustela, Linn. (Day's Motella mustela.) Not at all uncommon in Lancashire waters. I have obtained a medium-sized specimen from the shore in Barrovir Channel. 47. Three-bearded Rockling. Onus tricirrbatus (Bl.) Fairly common. 48. Halibut. Hippoglossus vulgaris^ Flem. The halibut is very scarce in Lancashire waters. I have not seen a specimen myself from inshore waters. When it does occur it is usually small. It is more often obtained south of the Isle of Man. A fisherman on Bardsey Island told me of a specimen taken on a line which weighed 80 lb. It was sold at Pwllheli for 8i. 49. Long rough Dab. Drepanopsetta plaUssoides (Fabr.) Day, Hippoghssoides Kmandoides. Very scarce in the Irish Sea. I have seen three or four specimens taken about midway between Lancashire and the Isle of Man. It is so uncommon that there is no local name for it, and it is usually called a ' kind of megrim.' 50. Turbot. Rhombus maximus, Linn. Rather uncommon. Small specimens are, however, taken in shallow inshore waters in the shrimp net. We have had it from the inshore waters of Blackpool, from Morecambe Bay, and from Barrow Channel. Turbot and brill in Lancashire waters are usually infested with the tapeworm Bothriocephalus punctatus. 51. Brill or ' Brett.' Rhombus Icevis, Rondel. More common than the turbot and with much the same distribution. 52. Norwegian Top-knot. Scolophthalmus nor- vegicus, Gunth. (Day's Zeugopterus norvegicus.) There is a specimen in the Fisheries Museum at the University of Liverpool which is probably local. 53. Bloch's Top-knot. Scolophthalmus unimacu- latus (Risso.) (Day, Zeugopterus unimaculatus.) Scarce. Two specimens were caught by Capt. Wignall near the Morecambe Bay light vessel in 1894. This is the only recent record I am aware of. 54. Muller's Topknot. Zeugopterus punctatus (Bl.) This is the commonest Topknot in Lan- cashire waters. Fishermen have no local name for any of these little flukes. They are often caughtin the shrimp nets, especially in Morecambe Bay and about the Ribble Channels. 55. Megrim or ' Magrim.' Lepidorhombus mega- stoma (Donovan.) Not uncommon, but not abundant enough in Lancashire waters to be of economic importance. 56. Scald-fish. Arnoglossus laterna (Walb.) More abundant than the megrim which it resembles. 57. Plaice. Pleuronectes platessa, hinn. Very abundant in Lancashire waters. The most valuable fishery in strictly local waters is that for the plaice. It is usually small and immature here on account of the active exploita- tion of Lancashire waters by fishermen. It is in all probability this excessive fishing which has produced the apparent correlation of the size of the fish with the depth of the water in which it is found. Generally speaking, the size of a plaice got in the Irish Sea varies directly (roughly of course) with the depth of water. Within the three mile territorial limit the plaice obtained in the trawl nets are small — from 8 to 1 1 inches. Occasionally a large fish may be found, but not often. The plaice becomes sexually mature at about 15 inches in total length in the female, and about 12 inches in the male. It is very rarely that such sexually mature fish are caught within the territorial waters. It is, however, to be noted that the cause of this distribution may not be that large fish find a natural habitat in deep water only, but rather that because of the great amount of fishing in inshore waters these large plaice have been ' fished out.' As a matter of fact, we find that in such an area as Luce Bay on the south coast of Scotland, where trawling is prohibited, large plaice from 15 to 22 inches long are relatively abundant. There is not the same intensity of fishing in offshore waters as within the narrow zone of territorial waters, and as a con- sequence we find that large plaice are found on these offshore grounds. There are no doubt very definite migration habits in the case of the plaice (and of course other flat fish), but so far these have been made out only very imperfectly. The Lancashire Sea Fisheries Committee have, however, been making extensive experiments quite recently with a view to determining the migration paths of the plaice, and some interesting results have been obtained. The fish are marked by fastening a little num- bered brass label to the body by means of silver wire. Records are then made of the size of the fish, the number of the label, date, place, and so on, and the fish is liberated. Experiments of this kind have only been made during the winter months, but they seem to show that the plaice in the inshore Lancashire waters move along the shallow coast waters during the early part of the winter, and finally come to rest in the bays and estuaries. Most of the liberated and marked plaice have been recovered from Morecambe Bay, the 183
