SEA-FISHERIES LABORATORY. 179 



AN EXAMINATION OF THE EXPERIMENTAL 



HAULS MADE IN THE MERSEY ESTUARY 



DURING THE PERIOD 1892 TO 1906 



INCLUSIVE. 



(Plate V.) 

 By H. J. Buchanan Wollaston. 



The present paper deals with the records of the 

 experimental hauls made on the Mersey Banks and in the 

 adjoining Channels, by the L. and W.S.F. steamer " John 

 Fell," and the New Brighton police cutter. The material 

 consists of several hundred sheets, dealing with nearly 800 

 hauls — there being 260 hauls made with shrimp-trawl nets, 

 70 with fish-trawls of various forms, and 13 with shank- 

 nets, all on the banks ; also 281 with fish-trawls, 163 with 

 shrimp-trawls, and 3 with shank-nets, all taken in the 

 channels between the banks. It was evident on examina- 

 tion of the records that the number of hauls made with 

 fish-trawls on the banks, and with shank-nets both on the 

 banks and in the channels were quite insufficient to afford 

 reliable conclusions. The shrimp-trawl-net hauls, both in 

 the channels and on the banks, and the six inch fish-trawl- 

 net hauls in the channels, are, however, sufficiently 

 numerous to warrant statistical treatment, and the results 

 have some interest, especially with regard to the variations 

 from month to month in the numbers of plaice and soles 

 on the banks. The method adopted was as follows : Every 

 haul was separately reduced to an hourly catch, that is, 

 to take a simple case, if the haul was of two hours' duration 

 the result was divided by 2. From all the hauls in each 

 month so reduced, an average haul was calculated, giving 

 the numbers of plaice and soles caught per hour's fishing. 

 The observations were, however, made rather irregularly, 

 and so in order to get a more reliable average catch per 

 hour for each month, the whole period cl fifteen years 



