52, 



MARINE AND FISHERIES 



1-2 EDWARD VII., A. 1902 



ing stations it may often be seen to feed greedily on the garbage of the fisheries, but I 

 have not known it to attack living animals.' Verrill ^ among other matters, deals 

 with the food of this animal, but his specimens must have been dredged or taken from 

 a part of the coast devoid of sea-weed for he found, like Sir William Dawson, the sur- 

 face sand. He says, on page 406 : ' The common green sea-urchin, Strongylocentrotus 

 drobachiensis, so very abundant further north, and especially in the Bay of Fundy, 

 where it occurs in abundance at low water mark, and on rocky bottoms at all depths 

 down to 110 fathoms, and off St. George's Bank even down to 450 fathoms, is compara- 

 tively rare in this region. It feeds partly on diatoms and other small algse, &c., which 

 it cuts from the rocks with the sharp points of its teeth, but it is also fond of dead fishes, 

 which are soon devoured, bones and all, by it in the Bay of Fundy. In return it is 

 swallowed whole in large quantities by the wolf fish and by other large fishes.' Packard ^ 

 found sea-weed, but does not mention the surface sand. He says : ' It eats sea- 

 weeds, and is also a scavenger, feeding on dead fish, &c. We have observed great num- 

 bers of them assembled in large groups, feeding on fish offal, a few fathoms below the 

 surface, in a harbour on the coast of Labrador, where fishing vessels were anchored.' 

 Although practically all who have investigated the food, have concluded that the urchins 

 are herbivorous, there is, seemingly, among zoologists a general belief that they are car- 

 nivorous. This is probably due to the fact that other groups of Echinoderms are un- 

 doubtedly carnivorous, and that a dead animal covered with urchins, is of course a very 

 conspicuou.s object and readily seen. 



Admitting that sea-weed is the principal food of the sea-urchin, it is impossible 

 that they could destroy enough of it, in any locality, to appreciably diminish the total 

 quantity unless within a recent period there had been an abnormal increase of urchins 

 in such district. Such an increase would be accounted for either by a decrease in the 

 enemies of the urchins, or by an increase in their food supply. It is known from the 

 observations of the British Fish Commission that sea-urchins are eaten by many large 

 fish, but it is probable that the large fish eat the urchins found in deep water and do 

 not approach those living in shallow water, which are the ones in which we are especi- 

 ally interested. Schiemenz ^ reports a case of an urchin being attacked and eaten by 

 starfish, but such occurrences are rare. Fishermen report that in winter the urchins 

 are eaten by crows and gulls, but the numbers destroyed in this way must be very 

 small, because the urchins are uncovered only at spring tides. It cannot be an increase 

 in the food supply which has caused an increase — if there really is an increase — in the 

 number of urchins because the sea- weed (their food) is said to be decreasing. Though 

 urchins, as will be shown, have been abundant on our coast for ages, there might be lim- 

 ited areas on which, for some unknown reason, there never have been many urchins. If 

 this is the case and the urchins are now becoming more numerous in such districts, the 

 increase will soon stop, and a balance between them and the sea-weed, such as is found 

 on the remainder of the coast, will soon be established. 



There are several reasons which lead me to believe that the sea-urchins will never 

 be able to strip our coast of seaweed, and that if there is a decrease of seaweed in any 

 district we must look for causes other than sea-urchins. In the first place an equilibrium 

 between the sea-urchins and the seaweed must have been established some ages ago, 

 because sea-urchins are among the most numerous of fossil animals and historic records 

 show that they have always been abundant on our Atlantic coast. Thus Champlain 

 mentions that urchins were common on Dochet's Island in 1604. In 1851 Dr. William 

 Stimpson ® collected on Grand Manan and describes the life on its shores as follows: 'The 

 shores of Grand Manan are covered, in many parts, with such numbers of sea-urchins, 



that it is impossible to make a step without crushing one or more of them 



It would be interesting to ascertain what constitutes the common food of such a multi- 

 tude of animals. I have seen a barren rock of several rods in extent, covered with 

 Echini, upon which no other animal^ nor any plant could be detected, which might serve 

 them for food. I should mention, that when a fish is killed by the fisherman and thrown 

 into the water, it becomes covered with Echini, who soon devour it.' If Dr. Stimpson 

 had examined the intestinal contents of these urchins he would, in all probability, have 

 found globular masses of sand which contained numbers of minute organisms. On 

 page 716 of the report before mentioned, Verrill ^ describes the sea-urchin as ' Very 



