302 NATURAL HISTOEY OF AQUATIC ANIMALS. 



" Sars has shown that this form of movement is taken by the herring on the Norwegian coast.' 



"The Mackerel are pursued by cod and hake, aud these fish gather where offal is thrown 

 over from vessels on which the Maclierel are cleaned. As a natural consequence the Mackerel 

 avoid the sea areas where their enemies are congregated, and fishermen attribute the desertion of 

 the mackerel ground directly to the throwing of offal overboard. Cod, and probably hake, follow 

 up the scent of offal or food of any description carried by currents with remarkable facility, as 

 may be witnessed during the process of jigging for cod in calm and clear waters. On looking over 

 the side of a boat, with a man engaged in jigging at the bow or stern, as soon as a fish is wounded 

 merely by the jigger and blood flows from the wound, the creature may be seen to dart here and 

 there in pain. The neighboring fish of the cod tribe are attracted by the scent and follow the 

 blood 'tracks' against the current, hunting their wounded comrade to the death. A fish coming 

 across the stream of scent immediately follows it up, and it is thus that fish offal or bait thrown 

 overboard in the open sea, or some distance from shore, gathers the fish on the course of the cur- 

 rent. In harbors and confined or land-looked b ays, where there is no constant strong current to 

 carry off the results of decomposition, and where the sea-scavengers are not sufQciently numerous 

 to consume it, the effect cannot fail to be extremely prejudicial to young fry and to fish-spawn.^ 



"The effect of temperature on the local movements of the Mackerel may be recognized in the 

 process employed by fishermen to 'raise' Mackerel by toll bait, and luring them seawards. The 

 Mackerel follow the bait for some distance from shore, where suddenly they cease to bite and dis- 

 appear. They probably find long exposure to the warm temperature of the surface waters unsuited 

 to their habits, aud sink to a cooler zone. 



"Hence the reason why a 'mackerel breeze,' mixing the heated surface water with the cooler 

 understratum, is favorable to prolonged mackerel fishing with bait. The mixing produced by 

 agitation cools the surface and permits the fish to feed for a lengthened period."' 



"The Mackerel, like the herring and the cod, seeks cold water for its spawning grounds 

 wherever the Labrador current exercises its influence. Between Block Island and No Man's 



naturalist. On one occasion, in the fall of 1867, an immense body of Mackerel was found along the north shore of 

 Cape Breton, and on the last day that the fish were seen the schools came near the surface of the water, and I feel safe 

 in saying, from actual observation, that they moved at a rate of no less than three or four miles per hour in the direc- 

 tion of the north cape of the island. On another occasion, a body of Mackerel that was found near Amherst Island 

 (one of the Magdalenes) one day, were met with the following morning about thirty miles distant from the first 

 locality, in the direction of the north cape of Cape Breton Island, towards which they were moving at the rate of one 

 or two miles an hour. I have myself seen schools of Mackerel off the Nova Scotian coast, in the fall, moving quite 

 rapidly in a westerly direction, but all efforts to catch them with a hook failed, since they seemed to pay no regard 

 whatever to toll bait. All of my own observations, aud those of the Nova Scotian fishermen with whom I have been 

 brought in contact, lead me to believe that Mackerel will not bite the hook to any «xteut during their fall migrations 

 along the southern coasts of Nova Scotia. This is all the more remarkable since they seem to take the hook very 

 eagerly up to the last moment of their stay on their feeding grounds in the gulf. The spring and fall migrations of the 

 Mackerel on our own coast are carried on with equal regularity and precision. On more than one occasion, in autunm, 

 I have followed these fish day after day in their progress to the south and west along the shores of Maine and Massa- 

 chusetts. On one occasion, in the fall of 1862, I caught Mackerel nearly down to the fishing rip on the Nantucket 

 Shoals. These fish were moving rapidly southward, and the schools could be kept alongside of the vessel only a short 

 time, and each trial had to be made two or three miles farther soutb than the previous one. At another time, in the 

 fall of 1870, the Mackerel moved in large schools very rapidly from Ipswich Bay across in the direction of Cape Cod. 

 The schools were at the surface of the water, and it is not an exaggeration to say that their speed was not less than 

 three or four miles an hour. Each body of fish was separated from the others, perhaps many hundred fathoms, but 

 all seenjed to be impelled by the same motive, and were moving steadily in the same direction. These fish would bite 

 eagerly at the hook for a few minutes at a time, but so strong was their instinct of migration that it was impossible 

 to detain thom only a short time in their onward movement. — J. W. Collins. 



' See chart by Dr. G. 0. Saks, in his report for 1874. 



''Fisheries of British North America, pp. 20,21. 



'Fisheries of British North America. 



