SEA-FISHERIES LABORATORY. 275 



and the Isle of Man to off the coast of North Wales. 

 This includes one or two fairly well defined spawning 

 grounds. The investigations carried on at the South - 

 "West of the Isle of Man in 1914 do not alter the approxi- 

 mate duration of the spawning period that is given in 

 the XXI Annual Report for the species dealt with below. 

 There is a well marked difference in the number of eggs 

 of the valuable food fishes present in the Bay compared 

 with the area outside, as shown by the tables given. It 

 is evident, therefore, that spawning takes place outside, 

 and the eggs are carried into the Bay by winds and 

 currents. 



The arrangement here is the same as that adopted in 

 the XXI Annual Report, page 233. 



Clupea sprattus, Liun. — Sprat. 



Eggs of the sprat were observed in the plankton 

 collected in Port Erin Bay on May 25th. They appeared 

 to be continually floating about this area during June 

 and July, but none were found later than July 30th. A 

 collection taken off Kilan Head in Cardigan Bay, by the 

 Fisheries steamer on April 5th, was estimated to contain 

 805 sprat eggs. Two were found in a haul 8 miles S.E. 

 of Point Lynus on May 6th. Our records extending over 

 eight years show that sprat eggs may occur in the 

 plankton from the beginning of April until the middle 

 of September. It is possible that the actual spawning 

 period in some parts of the Irish Sea may be even earlier 

 than is indicated by the presence of the eggs in the 

 plankton. The reproductive organs of sprats sent to me 

 from Morecambe for investigation on February 5th, 

 1915, were nearly all well advanced towards maturity. 

 In one or two cases the ovaries and testes were quite 

 mature. 



