23G THE vai;tation, eaces and :\riGRATiONS of the mackerel. 



of immature, but usually well-growu, mackerel come around the island. 

 According to one of the inspectors, the liev. W. S. Green, there is 

 a sharply defined interval between the two visitations of fish. 



The first result of the Treasury's communication was the preparation 

 by Mr. Allen of a report on the " Present State of Knowledge with 

 regard to the Habits and Migrations of the Mackerel," which was 

 published in this Journal in the autumn of last year. (vol. v., No. 1, 

 August, 1897, pp. 1-40.) This report contains a compendious and 

 suggestive summary of all the reliable information we possess up to the 

 present concerning the geographical and seasonal distribution of the 

 mackerel, its rate of growth and breeding habits, and the extent and 

 causes of its migrations. 



It will readily be understood that the investigation of the relations 

 between the spring and autumn fish of the Irish coasts could not 

 profitably be undertaken except as part of a general scheme which 

 should embrace the study of the mutual relations of the mackerel 

 of neighbouring seas as well ; for hitherto it has not been ascertained 

 whether the Irish fish as a whole are peculiar to Irish waters, or whether 

 there is any intermingling with the mackerel of the English Channel 

 and North Sea. The general impression appears to be that the mackerel 

 round all the British coasts form a single race or family, which becomes 

 dispersed during the summer in order to occupy the various seas and 

 channels round our islands, but becomes largely reunited in the winter 

 after the autumn migrations. Upon this theory the separation of the 

 mackerel family is determined principally by size, the larger fish 

 remaining near the shores of the ocean, from the Irish coast to the 

 Lizard, the smaller fish pushing their way northwards and eastwards 

 into the shallower waters of the Irish Sea, the English Channel, and 

 the North Sea. This view is expressed, for example, by Day in his 

 British Fishes, and by Mr. Matthias Dunn {Report Royal Cornwall 

 Polytechnic Soc, 1893). But the separation of the large Atlantic class 

 from the small class found in the more enclosed waters is not regarded 

 by these writers as in any way permanent. Every year, according 

 to Mr. Dunn, the Atlantic (or Irish) class receives a reinforcement 

 from the larger fish of the second (or shallow water) class ; while the 

 younger fish which have been bred off the Atlantic coast tend, in the 

 spring of the year, to make common cause with the fish which 

 frequent the English Channel. There is thus a complete mixture 

 between the two classes, which cannot consequently be regarded as 

 constituting local races in the sense in which we speak of Baltic 

 and North Sea herring as forming separate races. 



A still more decided view of the unity of the mackerel family has 

 been entertained by Mr. W. S. Green, the energetic Inspector of Irish 



