NA TURE 



\^Dec. 9, 1886 



winter and summer spawning-seasons. If herring ova 

 are capable of hatching in deep water (say from 60 to 100 

 fathoms) it may be tal<en for granted that any of the 

 many gravel coated banks of the North Sea may serve as 

 spawning-beds. The North Sea is remarkably shallow, 

 there being only one small area near our shores (generallv 

 known as the " Pot," and lying two to five miles off Fraser- 

 burgh), where a depth of 100 fathoms is reached. The most 

 certain way of proving whether herring ova hatch or not 

 in deep water would be to dredge herring spawn from one 

 of the off-shore banks in an advanced stage of develop- 

 ment ; but, after several unsuccessful attempts to do this, 

 it occurred to Prof Ewart that the question might be 

 practically settled by depositing fertilised eggs in spe- 

 cially constructed hatching-boxes in deep water. This 

 was done in the " Pot," but without result, as a storm 

 swept away all traces either of buoys or boxes. The 

 Moray Firth being in many respects unsuitable for this 

 experiment, Prof Ewart turned his attention to the West 

 Coast, and found a comparatively sheltered spot in Loch 

 Fyne, with a depth of 104 fathoms. To insure success, 

 a small tank was constructed of thick slate slabs firmly 

 bound together by iron rods. The tank, though only about 

 20 inches square, weighed nearly 2 cwts. In the top and 

 in two sides of this tank small windows were made about 

 5 inches square. Each window was carefully fitted with 

 a teak frame, across which a single layer of horsehair 

 cloth was stretched. These windows admitted a sufficient 

 current of water to pass through the tank. All the neces- 

 sary preparations having been made for depositing 

 the tank during last autumn. Mr. Brook, who was 

 engaged at the Fishery Board Tarbert Station during 

 the autumn, undertook to obtain eggs and superintend 

 the sinking of the tank in the loo-fathom water. Eggs 

 were obtained on September 11 from herring caught" ni 

 Kilbrannan Sound in water varying from S to 12 fathoms. 

 All the eggs were placed at first in the laboratory in 

 water which had an average temperature of 54- F. Most 

 of the eggs kept in the laboratory hatched out on the 

 19th, while others only batched on the 24th, thirteen davs 

 after fertilisation. On the i6th, one of the glass plates, 

 coated with eggs, was introduced into the tank above 

 mentioned, which was immediately conveyed to the 

 middle of the channel, and deposited in 9S fathoms water, 

 about three miles oft" Tarbert. The surface temperature 

 was 54'^ F., the bottom temperature was 49° F. The 

 bottom around the tank was chiefly composed of mud. 

 On the 24th— /.^. thirteen days after fertilisation, and 

 eight days after the eggs were deposited in 9S fathoms 

 water— the tank was raised. On examining the glass 

 plate, it was found a number of the eggs in the centre had 

 been destroyed by a fine coating of mud, which had 

 entered through the hair-cloth screen, while those near 

 the margins contained vigorous embryos almost ready to 

 hatch ; in a l<t\i cases hatching had taken place. The 

 average bottom temperature while the eggs were deposited 

 was 49'-3 F. ; the average surface temperature, 54° F.,— 

 the difference being 4= 7. The diflerence of 4°7 during 

 the eight days which the eggs were deposited delaved 

 hatching for about five days. This experiment clearly 

 shoxys that the only difference between the hatching of 

 herring ova in deep and shallow water is one of time ; 

 hence we are safe in concluding that if herring deposit 

 their eggs on suitable ground, in any depth of water not 

 exceeding 100 fathoms, they will undergo development. 

 It is conceivable, however, that the depth of the water in 

 which the eggs are deposited may have some influence on 

 the time of spawning— in other words, on the fishing- 

 season ; and the immature condition of the fish caught 

 n August during recent years may to some extent be 

 accounted for in this way. If the herring which formerly 

 spawned on the in shore banks of the "Moray Firth in 

 from 10 to 20 fathoms water now spawn off-shore in from 

 40 to 60 fathoms water, the hatching will be delayed for 



several days, and maturity will not be reached as early as 

 formerly. This is an argument in favour of beginning 

 the herring-fishing later in the season than at present. 

 It may be objected that the fry, if hatched out in deep 

 water, would never succeed in reaching the surface ; 

 and supposing that they could, the necessary food 

 mtght not be found forty to sixty miles from shore. 

 Observations, however, show that the young herring are 

 likely to have little difficulty in ascending 200 fathoms 

 before the yolk-sac is exhausted, and that though no 

 one is yet well acquainted with the food of the fry, there 

 can be no doubt about the richness of the surface fauna 

 beyond even the fifty-mile line. 



In the Report for 1883, Prof Ewart called attention to 

 the fact that the German Commission had arrived at the 

 conclusion that the Baltic herring differed sufficiently 

 from the North Sea herring to be worthy of being con- 

 sidered a special variety. It has long been held by fisher- 

 men and others that each district has its own peculiar 

 variety. From some 500 specimens examined in 1S83, 

 no evidence of the existence of such varieties was found. 

 In order to settle this question finally, Mr. Duncan 

 Matthews has been examining, for a considerable time, 

 samples of the herring captured around the Scottish 

 coast, and now communicates an important paper on this 

 subject. The method of investigation adopted was to 

 take accurate measurements of the length of the head, 

 and of the caudal, dorsal, and anal fins, to note the posi- 

 tion of the fins on the body, &c., and, by a comparison of 

 these data with the length of the body, to ascertain the 

 amount of their actual variation, and especially whether 

 these variations were so constant in the herrings of any 

 one or more localities or seasons as to indicate a distinc- 

 tion of races. From this inquiry it seems that there are 

 as large herring now as there were some generations ago, 

 and that, although each district yields large herring, the 

 north-east coast has a slight advantage in this respect 

 over the south-east and west coasts. .A table giving the 

 size, ■Sic, of the largest fish examined includes repre- 

 sentatives from every fishery district, and shows that 

 there is no practical difference in size between the male 

 and female, nor in the numbers of each of these which 

 were taken. The winter fish are found to be rather larger 

 than those taken in summer, while among the fish com- 

 mercially termed " maties " there are (i) immature herring, 

 i.e. herring which, in addition to being small in size, have 

 undeveloped milts or roes ; (2) small herring in all degrees 

 of ripeness up to maturity ; ("3) small herring which have 

 spawned — small "spent" herring. Hitherto, the size of 

 the fish, rather than the sexual condition, has apparently 

 determined whether the term "matie" should be applied. 

 In the same districts, and even in the same shoals, lar}^e 

 sexually immature herrings are often found along with 

 .rwrt//ripe, or nearly ripe, herring ; hence herring appear 

 not only to vary in size in their fully adult condition, 

 but also to vary in the size at which they reach sexual 

 maturity. It is pointed out that these results, as well as 

 the fact that the undivided ova vary in size in ratio to the 

 size of the fish, are likely to cause considerable variation 

 in the progeny which result from the interbreeding of 

 fiih of varying j/^t' and age. Of the fish caught in the 

 early part of the season, a much larger proportion are 

 immature and small, and probably also younger than is 

 the case later on. The adult fish appear to reach a more 

 advanced stage of ripeness before they approach the 

 spawning-banks. From the measurements made, it is 

 shown that the length of the head varies considerably 

 the extremes being found in herrings of all localities and 

 both seasons, the percentage with the larger size of head 

 being rather greater among the winter than the summer 

 herring ; but this difterence, like thit of the total length, 

 is considered insufficient to prove a racial distinction. 

 The position of the centre of the dorsal fin in a majority 

 of the winter herrings is anterior to the centre of the 



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