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NATURE 



[December 15, 1892 



Travel." The Society presented Capt. Lugard with its silver 

 medal and an honorary diploma of Fellowship. A similar 

 award has been made to Mr. Joseph Thomson in recognition of 

 his services to Geography in Africa. 



Dr. J. Troll, an Austrian explorer, is at present engaged 

 in a journey through Central Asia. He reached Samarkand in 

 the end of October. Thence he proposes to pass through 

 Russian and Chinese Turkestan and Mongolia, intending to 

 return by Pekin and Shanghai. In the course of his journey he 

 hopes to visit the ruined city of Karakoram, the ancient capital 

 of Jenghiz Khan. 



A RAILWAY has recently been opened from Wiborg, in Fin- 

 land, to the Imatra Falls, thus bringing the finest rapids in 

 Europe within six hours of St. Petersburg. Hitherto the falls 

 have been reached by canal-steamer and coach, the journey 

 occupying not much less than twelve hours. 



Mr. Joseph Thomson proposes to use the name " Living- 

 stonia " to describe the whole British sphere of influence north 

 of the Zambesi and west of Lake Nyasa. It is little to the credit 

 of British cartographers that the attempts hitherto made to 

 associate Livingstone's name with the continent of which he was 

 the greatest explorer have practically failed. 



THE DESTRUCTION OF IMMATURE FISH. 

 lyrR. ERNEST W. L. HOLT contributes to the new number 



■^ of the Marine Biological Association's Journal another very 

 interestinjj paper on the results of his North Sea Investigations. 

 He has much to say as to the destruction of immature fish in the 

 North Sea, and makes the following observations on proposed 

 remedial measures : — 



It will be admitted that the continued destruction of large num- 

 bers of valuable fish before they have had a chance of reproducing 

 their species can only result in increased deterioration of the in- 

 dustry, and that some measures must be taken to put a stop to it. 

 unless we are prepared, and able, by artificial propagation to re- 

 stock the sea as fast as we deplete it. Briefly the various proposals 

 that have been put forward fall under three headings, viz. closure 

 of grounds frequented by small fish, restriction of sale of 

 undersized fish, and enlargement or alteration of mesh. We have 

 seen that some of the smack-owners have adopted the eminently 

 practical method of forbidding their boats to fish where they are 

 likely to catch much small stuff"; but the buyers, though as loud 

 as any in their outcry, do not appear inclined to avail themselves 

 of their undoubted power to check the evil. The proposals 

 for legislative action have been so much discussed of late that 

 I need only advert to such as affect the North Sea district. 



It is a matter of common knowledge that the bulk of the de- 

 struction by deep-sea trawlers takes place on the eastern grounds, 

 to which I have alluded elsewhere ; and since these lie wholly 

 or in part outside the three-mile limit; it has been proposed that 

 they shall be closed to trawling by international agreement. 

 Whether such agreement could ever be arrived at is questionable 

 and if it were, it is not likely that the ensuing legislation could 

 be easily enforced. The great extent of the grounds would in- 

 volve an enormous and costly Marine Police force, of mixed 

 nationality ; and even were such a body much more efficient than 

 one has any reason to expect, there might be considerable diffi- 

 culty in adequately watching grounds which extend in some 

 cases over fifty miles from shore. Indeed, on our own coasts 

 and elsewhere the success with which legislation limited to the 

 territorial area has hitherto been enforced is hardly such as to 

 encourage us to extend the principle to the open sea. 



The various standards of size which have been advocated, in 

 proposals for prohibiting the sale or possession of undersized 

 fish, differ according as the subject has been treated with regard 

 to the marketable qualities of the fish, or to its powers of repro- 

 duction ; and it may be assumed, I suppose, without argument 

 that the latter is the more rational method of treatment. Still 

 it may be as well to recapitulate the sizes proposed at the Fishery 

 Conference at Fishmongers' Hall last February, since they may 

 be taken to represent the most recent trade opinion on the 

 subject. 



They are for turbot and brill twelve inches, for soles and 

 lemon sole [Pletironecies microcephalus) ten inches, and for 

 plaice eleven inches. How far they fall short of the biological 

 limits, at least for the North Sea district, can be judged by com- 

 paring them with the table of sizes on p. 384 of the Journal ; 

 and, indeed, I may remark that the prohibition of the sale of 



NO. 1207, VOL. 47] 



turbot and brill under twelve inches in length is rather a work 

 of supererogation, since the number of smaller iish of these 

 species that come to market, at all events at Grimsby, is utterly 

 insignificant. 



The benefit to be expected from any measure of prohibition 

 depends of course on the vitality of the fish, and it is very 

 generally asserted that the bulk of the small fish trawled on 

 these eastern grounds would not survive if returned. My own 

 experience leads me to believe that this view is correct^ so long 

 as the present system of long hauls is maintained. Hence we 

 must seek for such a limit as will render the grounds most fre- 

 quented by these small fish unprofitable to the fishermen (since 

 any less limit would only involve an infinitely greater waste than 

 takes place at present), and in doing so it is necessary to glance 

 at the general conditions of this fishery. 



Exclusive of less important forms, the species chiefly met with 

 are plaice, turbot, and soles. The plaice, on most grounds, do 

 not exceed a length of fifteen inches, and are mostly less than 

 thirteen inches in length. The turbot are fairly abundant, but,, 

 as I have already shown, almost all immature ; soles are scarce. 

 It is ofily the certainty of being able to fill up with small plaice 

 that induces the fishermen to cross to the eastern side, since the 

 soles and turbot would not nearly pay his expenses by them- 

 selves. Now I am confident that if the Conference limit of 

 eleven inches for plaice were enforced, there would still be 

 enough saleable fish left to make the grounds worth visiting, 

 whereas if it were raised to fifteen or even fourteen inches the 

 grounds would assuredly be left alone ; and although such would 

 be below the biological limit, I believe the practical closing to 

 our huge fleets of such a magnificent nursery for young plaice 

 would be in itself a sufficient protection for the species. Certain 

 rough patches of ground, practically surrounded by areas yield- 

 ing only small fish, abound with only large fish ; these would 

 still be accessible to fishermen, whereas in any scheme of geo- 

 graphical restriction it would hardly be possible to exempt them. 

 Moreover the restriction of size would probably do away with 

 the destruction of small plaice by shrimp or sole-trawls, since 

 the fish are not injured by being caught in these nets, and if un- 

 saleable2 would probably be returned. 



For turbot, brill, and sole I would advocate the adoption of 

 the biological standards. They are all rather hardy forms, and 

 it appears that immature brill and such immature turbot as are 

 found on our ow n coasts are chiefly caught on certain banks 

 where the intricate nature of the ground renders short hauls a 

 necessity, so that they could be returned to the sea in good con- 

 dition, as indeed the smaller of them usually are at present by 

 many fishermen. With regard to soles, I do not think that many 

 undersized fish are caught by deep-sea trawlers,' and the substi- 

 tution of a size limit for the present prohibition of the use of a 

 fish-trawl in the Humber would do away with the anomaly of a 

 law which is not enforced. There is a strong feeling- amongst 

 inshore fishermen that the bye-law alluded to is unequal in its 

 operation, since it offers no check to the destruction of small fish 

 on off-shore grounds, only accessible to large boats. Hence a 

 regulation as to the size of fish landed is perhaps preferable ta 

 one based solely on territorial conditions somewhat imperfectly 

 understood. 



An objection which I have heard urged against any scheme 

 for keeping our trawlers off the eastern grounds is that the 

 summer sole trade in the North Sea would thereby be left entirely 

 in the hands of foreigners. I think that this is, perhaps, rather 

 overstating the case, but anyhow I caimot see that it furnishes 

 any excuse for the present enormous destruction of small plaice 

 and turbot, whilst it is at least possible that the abstention of our 

 own fleet from these grounds in the summer would result in a 

 corresponding increase in the number of soles in the localities 

 where that species congregates in the winter months. I have no 

 knowledge of the migrations of soles, but the Great Silver Pit is 

 equidistant from the Humber and the nearest eastern ground, 

 and as it is the nearest point at which similar physical conditions 

 can be attained, it does not seem improbable that the winter 

 supply of soles in the Pit is in part recruited from the east side 

 of the North Sea. 



I Owing to the great mass of fish caught in a single haul, I consider it quite 

 possible 10 hold this view without throwing any doubt on the value of the 

 results obtained by my (riend Dr. Fulton in his experiments on the vitality 

 of trawled fish (Report S F. B., 1891;. 



- The possession, asw'ell as the sale, should be prohibited, to guard agains 

 the possible dangei of small fish being utilized as manure when the fisherman, 

 is also a farmer in a small way. 



3 The small soles caught on the Dogger and on the Dowsing are really 

 solanettes {Solea minutd). 



