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TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



REPORT ON THE PERIODIC SAMPLES OF SHRIMPS 

 FROM THE MERSEY ESTUARY. 



By T. Monaghan, 

 Assistant Naturalist in the Fisheries Laboratory. 



During 1913 and part of 1912 samples of shrimps were 

 received periodically from the Fisheries Bailiff (Captain Eccles), 

 which I examined and measured. The approximate averages 

 of berried females, non-berried females, and males were also 

 found for each sample. The samples were taken from the 

 fishing grounds in the Rock Channel and the Crosby Channel, 

 both of which may be spoken of as the " Mersey Estuary." 

 On examining the shrimps individually it was found that the 

 eggs were most abundant from January to August, and the 

 proportion of the berried females then diminished from 

 September to December. It will be noticed from the following 

 tables that the samples were not sent for examination every 

 month on account of difficulties in obtaining them, so that 

 definite conclusions cannot yet be arrived at from the investiga- 

 tion. The data, however, are given here, and the observations 

 will be continued with greater regularity this year. Table I 

 gives the rough data. Table II gives the percentage of males, 

 berried females, and non-berried females. The chart below 

 represents the latter variation graphically. 



MALES. 



VNON-BCRRIED 

 FEMALES. 



BERRIED FEMALES. 



JAN I FCQ I MArIaPRuJmay IjUNeIjULY Iau& IsEPtIoCT I NOV IDEC I 



Fig. 1. Variation in the percentages of males, non -berried females, and 

 berried females in shrimps caught in the Mersey estuary. 



