172 Part III. — Twenty-second Annual Report 



escaped capture either wholly or largely by passing out through the meshes 

 of the net, although they may have been present in the water in consider- 

 able numbers. This, however, does not entirely account for the fact 

 which is apparent from the measurements in the tables and from the 

 curves, that it was the rule to get only one series of sprats, with a certain 

 range of sizes, in the same haul, while in another haul in the same locality 

 later, or at the same time in another place, quite a different series 

 predominated. That seems to be due to the sprats of different years 

 keeping for the most part separate from one another. 



The number of collections obtained and examined was twenty-six, 

 some in each month of the year except February, July, and August ; 

 most of them were obtained in October and December. 



From the fact that the spawning period of the sprat is definitely 

 limited to one portion of the year it is more easy to determine its rate of 

 growth than in the case of the herring, in which there are two well 

 separated spawning seasons, spring and autumn, and a certain degree of 

 spawning iii the intermediate periods. The sprat appears to spawn at 

 different parts of the coast at rather different times, or at all events the 

 spawning period does not quite coincide. At Plymouth, Cunningham 

 found it spawning from the end of January until the end of April, or 

 even later.* On the west coast of Ireland Holt obtained the floating 

 eggs in March, April, May, and June ; chiefly in March and April. t 

 Hensen and Apstein give the spawning period as the end of April and 

 the beginning of May.J On the east coast of Scotland the Gadayid 

 found the floating eggs in the Firth of Forth from towards the end of 

 March to the middle of August, and especially in April, May, and June. 

 In the Moray Firth I found sprats to be spawning on the 1st April and 

 1st June ; and though the limits of the period here are not well defined, 

 there is no reason to doubt that they are much the same as a little further 

 down the coast, and probably the chief spawning occurs about the end of 

 May on this stretch of coast. 



From the small size of the egg and the temperature of the water at 

 that season the hatching of the eggs takes only a few days, the length of 

 the larva, according to Cunningham, being from 3 to 3"7mm. Probably 

 the early part of June may therefore be taken as the period when the 

 bulk of the larval sprats issue into the water. 



The smallest specimens got after the spawning season were obtained in 

 September and October in Aberdeen Bay and in the Moray Firth in 

 December, in all cases by the tow-net. On the 18th September, near 

 shore, in from seven to ten feet of water in Aberdeen Bay, sixteen were 

 taken from 29mm. to 46mm., and on the 20th other five measuring 

 from 29mm. to 39mm., the average size of these twenty-one specimens 

 being 35 •9mm., or If inches. On 18th October, in nine fathoms, in the 

 same locality, four were caught which measured 31, 35, 42, and 45mm. 

 On the 28th December in the Dornoch Firth two were taken in the 

 tow-nets, one of which measured 39mm. and the other 48mm., while 734 

 were caught in the small-meshed net around the cod-end, ranging in 

 size from 52 to 125mm. It is obvious that all the small sprats taken 

 in these drags had been hatched in the previous spawning season, 

 and were approximately from three to six months old. 



In April, some small sprats were also got in the shrimp net in shallow 

 water in Aberdeen Bay. On the 8th of the month three were taken 

 which measured 45, 59, and 53mm., as well as a number from 65mm. 

 upwards. On the 16th of the month other fifty-one were taken with the 



* " The Natural History of the Marketable Marino Fishes," p. 165. 



\ Rep. of Oouncil, Roy. Dublin Soc. Jor 1891, p. 265. 



X Wissen. Meeresuntersiich. Kiel Commis. Neue Folge, Bd. 2 Heft 2, p. 37. 



