SEA-FISHERIES LABORATORY. 287 



Liverpool Bay are too far away to exert any appreciable 

 influence ; hence the temperature of the water here is not 

 influenced by the land to the same extent as it is off 

 the coasts of Lancashire and Cheshire. The main drift 

 of water is from St. George's Channel round the coast of 

 Anglesey into Red Wharf and Beaumaris Bays; and 

 since this water is colder in the summer, and warmer in 

 the winter than that normally present in the sea off 

 Liverpool Bay and the coasts of North Wales, so the 

 temperature in this area is more uniform than it would be 

 in the absence of this inflow. Still the land does exert 

 an influence, and so the temperature range in these areas 

 is greater than it is in the fairway of the Channel. The 

 very important winter plaice fishing grounds in Red 

 Wharf Bay, off Point Lynus, in Beaumaris Bay and off 

 Great Orme's Head, and in Channel Course (that is, in 

 the track of vessels approaching Liverpool Bar from 

 Point Lynus) are situated in this area. 



These temperature differences are best shown by the 

 isothermal lines plotted on Charts I to IV. The chart 

 drawn for February is for 1913, since the only hydro- 

 graphic stations visited during February, 1912, were those 

 on lines 1 and 2, and these points are insufficient to define 

 the isotherms exactly. It should be noted that these charts 

 represent the differences of temperature in a broad 

 manner only, and that much more numerous observations 

 would certainly show that the isothermal lines run 

 more irregularly than represented, although their 

 general direction might still be the same. It is very 

 probable that they are quite sufficient for the investigation 

 of any relationship between temperature and fishery 

 periods or productivity that may possibly exist. 



Chart I represents the distribution of temperature 

 during May — one of the " mean " months. The prin- 



