FEEDING HABITS OF MACKEREL. 401 



In the present state of our knowledge with regard to the winter 

 habitat of the species, it is impossible to even hazard a suggestion as to 

 how far many of these fish, caught in the height of the season, have 

 travelled, yet the fact remains that productive fishing is carried on 

 nearer and nearer to land as the season continues. 



It is a somewhat difficult matter to obtain precise information with 

 regard to the rate of progression of a single shoal of drift fish. Mathias 

 Dunn, senior, stated that this in the case of pilchards, when on 

 migration, was about li miles an hour.* 



Some information gathered at Sidmouth in 1911, moreover, may be 

 worthy of record. The writer was informed by two boatmen who were con- 

 stantly sailing over the area under consideration, that a shoal of small 

 mackerel was first observed oft" Start Point at the beginning of July. 

 It passed too far out from Dartmouth and Exmouth to be taken in a 

 seine, but w^as fished for by certain drifters within a few miles from 

 land. The shoal finally came close inshore to the west end of the sea- 

 front at Sidmouth, where the greater part were taken in a seine, the 

 remnant passing farther to the east. The time occupied in covering 

 the total distance (which in a straight line is about 33 miles) was 

 stated to be about nine days. 



From a consideration of the above statements, several questions per- 

 tinent to the question of selective feeding naturally arise. In the first 

 place, it may be suggested that when once distinct migration commences, 

 whether it be a " spawning " or a " feeding " migration, mackerel make 

 more or less regular daily progress towards inshore waters in the area 

 under discussion, their movement being undeterred by the influence of 

 currents. If this be the case, it naturally follows that were the fish to 

 swim vigorously forward in the indiscriminate pursuit of plankton, 

 at a pace sufficient to enhance the catching power of the mouth, their 

 progress toward the land would be considerably more rapid than it 

 appears to be from the slender evidence before us. 

 - The speed, at which the small mackerel already mentioned crossed 

 Torbay and the adjacent water, appears to have been about three to 

 four miles a day. From observations made at Sidmouth by the present 

 writer upon fish of this type in the years 1910-11, the food consisted 

 for the greater part of caradid larvae with a few copepods, certainly, 

 on the whole, organisms which might have been hunted by sight. 

 How did these fish, therefore, take so long in covering the distance 

 cited, unless whilst maintaining a shoal formation they were con- 

 tinually rounding up their prey in ceaseless movement, similar to that 



* Dunn, M., "Some Habits of Picked Dogs, Herrings and Pilchards," 5Uh Ann. 

 Rep. Royal Cornwall Polytechnic Soc, p. 5. 



