106 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



than + 0*5. But in the smaller catches this error may 



actually be present. In these latter cases it is more 



accurate to " smooth " the figures by the use of the 

 formula 



Mean length of group b — — «— 



this summation and division being applied to every three 

 contiguous groups in the series. 



They are grouped according to locality, beginning 

 with the more northerly fishing grounds. The numbers 

 of fish from Luce Bay and the Clyde are small, but are 

 useful for comparison with the truly Irish Sea fishing 

 grounds. The fishing grounds off Duddon Buoy, in, and 

 off Barrow Channel, and in the estuary of the Rivers 

 Wyre and Lune might possibly be regarded as one natural 

 area ; nevertheless they are tabulated separately : one 

 learns to avoid " lumping " as much as possible. Black- 

 pool Closed Ground and the grounds off Nelson Buoy are 

 probably rather different, but the number of fish caught 

 is small and the hauls have been combined. The Mersey 

 area presents marked differences : Rock Channel contains 

 quite a different kind of plaice from the grounds in Horse 

 Channel, or near the Mersey Bar. Probably the grounds 

 near Great Orme's Head and in Beaumaris (or Conway) 

 Bay, and in Red Wharf Bay are very similar, but the fish 

 taken in these areas are separately tabulated. A few 

 catches are recorded from Carnarvon and Cardigan Bays, 

 but so far we have not paid much attention to these parts 

 of the District. The Sketch Chart opposite page 106 gives 

 the approximate positions of these areas. 



All the catches made in each area in each month 

 have been added together. The month is, of course, a 

 purely arbitrary division of time, and the ideal method 

 would be to give the figures for each haul. But 



