

SEA- FISHERIES LABORATORY. 119 



(/) Marking experiments were made. These began in 

 1906 and were carried on until 1913. Two areas were seen to 

 be of much importance : the grounds of! Nelson Buoy and 

 those in Red Wharf and Beaumaris Bays, and most of the 

 experiments were made there. In 1920 and 1921 the experi- 

 ments were renewed and plaice were marked on the grounds 

 between Isle of Man and the Solway Firth. In all cases the 

 English form of mark was used ; at first the bone button and 

 brass label, and later the vulcanite buttons and labels. 



(g) In 1921 the larval and post-larval plaice were 

 studied. Catches were made by means of the Lancashire 

 " push-net," which is used to catch shrimps, being pushed 

 along the sea bottom, in water of two feet or so in depth, by a 

 man wading. The flat fishes collected in this way (from the 

 Cheshire coast and the coast of the Isle of Man) were identified 

 and measured and their food contents were recognised. Larval 

 and post-larval plaice from the Hatchery at Port Erin were 

 also collected and their food was examined. 



(h) Other investigations (Embryogen}% variability) were 

 contemplated, but have not so far been adequately made. 



(3) Treatment of the Data. 



Not very much was to be made out of a direct comparison 

 of the numbers of fish caught per hour's trawling, on the 

 various grounds, and at different times. The standardisation 

 of the fishing gear and vessels and of the canditions under 

 which the experimental hauls were to be made, were too 

 difficult. In no case have we had, at our disposal, a vessel 

 used exclusively for scientific research, and all the work had 

 to be done on board the police steamers and sailing boats, or 

 on board steam trawlers, smacks, and inshore trawlers. It was, 

 of course, very gratifying that the L.W.S.F. Committee allowed 

 us the use of their vessels, and we are also much indebted to 

 the owners and masters of the commercial boats, who allowed 



