48 BULLETIN OF THE BUREAU OF FISHERIES 



of the great schools that may visit one part of the coast one summer and another 

 part the next, there being no general alteration of the stock, but the many fishermen 

 who reported to the Massachusetts Commissioners in 1905 were so unanimously of 

 the opinion that dogfish had multiplied steadily for 20 to 30 years past as to point 

 unmistakably to the conclusion that the species as a whole was then in one of the 

 periodic upswings characteristic of various other fishes. Reports from British 

 coasts are to the same effect. Perhaps the years 1904-5 marked the apex of this 

 wave of multiplication; at any rate dogfish were reported as distinctly less trouble- 

 some to the mackerel netters in 1913 than in previous years, and since that time 

 less complaint has been made of them, though it is too soon to say whether a general 

 diminution of the stock is actually in progress. 



Much has been written of the habits of the spiny dogfish, all to the effect that 

 it has nothing to recommend it from the standpoint either of the fishermen or of its 

 fellow creatures in the sea. It is one of the more gregarious of our fishes, swi mm ing 

 in schools or packs. Swedish fishermen assert that young dogs school separately 

 from their parents, and it is certain that fish of a size continue to associate together 

 as they grow, the result being that any given school runs very even, consisting as a 

 rule either of the very large mature females, of medimn-sized fish (either mature 

 males or immature females), or of small immature fish of both sexes in about equal 

 numbers. '' 



Apart from its general seasonal migratory movements, the dogfish are governed 

 by the movements of the fishes on which they prey and in pursuit of which they 

 roam about, striking in here and there in multitudes. Fortunately they seldom 

 stay long in one place, but there is seldom, if ever, a time during the summer when 

 they are not common on some part of the Gulf of Maine coast. So erratic 

 are their appearances and disappearances that where one has good fishing to-day 

 he may catch only dogfish to-morrow and nothing at all the day after, the better 

 fish having fled these sea wolves and the latter departing in pursuit. 



The dogfish use their back spines for defense, curling around in a bow and 

 striking, which makes them hard to handle on the hook. It is probable, too, that 

 the spines are slightly poisonous, general report to this effect being corroborated 

 by the fact that the concave surfaces are lined with a glandular tissue resembling 

 the poison glands of the venomous "weever" {Trachinus draco)?'' 



Strong, swift-swimming, voracious almost beyond belief, the dogfish entirely 

 deserves its bad reputation. Not only does it harry and drive off mackerel, herring, 

 and even fish as large as cod and haddock, but it destroys vast numbers of them. 

 Again and again fishermen have described the sight of packs of dogs dashing among 

 schools of mackerel, and even attacking them within the seines, biting through 

 the net, ruining the gear, and releasing such of the catch as escapes them. 

 Often, too, they bite groundfish from the hooks of long lines, take the baits and 

 make it vain to fish where they abound. In Massachusetts and Ipswich Bays, 



3« Ford (Journal of the Marine Biological Association of the United Kingdom, new series, Vol. XH, No. 3, Sept., 1921, pp. 

 468-505, Plymouth, England) has recently published very interesting notes on this and other phases of the life-history of the spiny 

 dogfish, with a summary of the earlier statements as to the breeding season. 



" Dale (Philosophical Transactions, Royal Society of London, series B, Vol, 212, 1923, p. 27) describes the spines and gives 

 clinical records of the effects of wounds inflicted by them. 



