356 



NATURE 



[July 3, 1919 



concerned about the capture of full-sized herrings by the 

 ordinary trawl in daylight. A useful summary of the 

 present knowledge of the mackerel fishery in Den- 

 mark, Sweden, Norway, Holland, Germany, Scotland, 

 England, Ireland, France, Southern Europe, and the 

 North-West Atlantic came from Ehrenbaum, the usual 

 variations occurring throughout. This variability was 

 further emphasised by Dr. Hugh Smith, of the United 

 States, in the decline of the fishery there from 

 500,000 barrels in 1885 to 3000 in 1910; yet it had 

 not been proved that the fishes had migrated to other 

 grounds, such as western Europe, or had been deci- 

 mated by the purse-seines.' Moreover, a similar 

 experience had been met with in Norway. 



As the oft-repeated statements concerning the 

 diminution of the flat-fishes (Pleuronectids) had at- 

 tracted ■ public notice, the Council devoted a large 

 amount of attention \o this group. Thus Ehrenbaum, 

 in two papers, took in hand the early stages from the 

 eggs onwards, and their occurrence according to the 

 months of the year; whilst Johansen discussed them 

 in relation to the North Sea generally, a certain 

 amount of duplication taking place. Ehrenbaum 's 

 first paper, perhaps, was the less important, for the 

 subject had in many respects been dealt with 

 previously. In his second paper he groups the pelagic 

 eggs according to the presence or absence of an oil- 

 globule, and appends two plates, the figures on which 

 had, for the most part, been published by other 

 authors. Hefford describes the proportional distribu- 

 tion of plaice in the North Sea, males slightly pre- 

 ponderating in small plaice, whereas in the larger 

 forms females are in the majority, vet in the breeding 

 season in the south (December to February) the catch 

 of males by trawlers greatly exceeds that of females. 

 Masterman's three reports on the late stages of the 

 flat-fishes give much important information and note- 

 worthv recommendations, but there is no indication 

 of a serious diminution of any form. On the other 

 hand, Johansen considers that the average weight of 

 plaice in the Danish region of the North Sea has dis- 

 tinctly decreased since 1888 — a different finding from 

 a much longer experience in St. Andrews Bay. 

 Heincke dqj-^) is of opinion that the Danish and 

 German investigations show a deterioration of the 

 stock of plaice, and that, apart from over-fishing, the 

 destruction of small plaice is in itself sufficient to 

 render protective measures desirable. He has not, 

 however, proved that the small plaice are reduced in 

 number — a vital point — and this though he states that 

 300,000,000 are annually destroved, irrespective of the 

 capture of plaice from two to thirty years old for sale, 

 onlv 10 per cent, of which have produced eggs. He 

 therefore proposes the sole legislative measures which 

 the sixteen vears' costly labours of the Council have 

 produced, viz.: (i) Protection of the voung plaice; 

 (2) closed areas and seasons ; and (-x) a size-limit. 

 The revival of the old size-limit is interesting, but 

 its apnlication is more than doubtful, esoeciallv when 

 Heincke cannot prove definitely that plaice have 

 diminished. Redeke concludes with an account of 

 th'' locnl forms of plaice in Danish waters. 



The Council has. indeed, expended a great amount 

 of labour on the plaice, and it is no lack of sympathy 

 with the various authors of the memoirs which 

 prompts the statement that no trustworthy conclusion 

 as to its serious diminution can be drawn from them, 

 and they are in some respects duplicated. No author 

 can definitely assert that the plaice is on the road to 

 extinction. It is said that evidence to the effect that 

 the diminution of the plaice "was already made clear 

 to the House of Commons in 1803, and that all 

 authorities are agreed that this fish shows sprious 

 diminution." But the statistics of the Fishery Board 



S Th'S fishery has now largely improved. 



NO. 2592, VOL. 103] 



on which I and others relied in 1893 were found by a 

 more stringent examination to be in need of modifica- 

 tion, and in the history of the fisheries the plaice, as 

 already mentioned, has of old been the subject of 

 pessirriistic views, just as those accounting for the 

 absence of large plaice in inshore shallow waters — by 

 over-fishing— rest on a misapprehension of the life- 

 history of the species. The conjectures that only 

 10 per cent, of the captured adults have produced 

 eggs, and that the removal of 20 to 40 per cent, 

 from the North Sea annually is too great a loss to 

 be compensated by natural means, are not the clear 

 facts demanded by science and the State. Plaice have 

 been taken from the North Sea from time im- 

 memorial, and yet are distributed to-day over its 

 entire area, whilst their tiny young swarm on every 

 suitable sandy or muddy beach. Though it is to be 

 regretted that the destruction of the small plaice 

 crowding on the sandy flats of the Continental shores 

 still goes on, yet there is no marked diminution in 

 their numbers. Heincke's suggestions for the protec- 

 tion of the young are of doubtful practical utility ; 

 besides, as Masterman says, why confine legislation 

 to the plaice when the other flat-fishes are likewise 

 supposed to be in need, and the round-fishes 

 have an equal claim? Perhaps the pressure brought 

 to bear on the Council to produce, after its 

 lengthened labours, something tangible in the way of 

 legislative recommendations may have had some con- 

 nection with this step. 



In "The Analysis and Review of the English Plaice- 

 marking Experiments," published in 1916 by the 

 Board of Agriculture and Fisheries, less ambitious 

 views were promulgated, though it was thought that 

 the transplantation of plaice on a commercial scale 

 might yield a profit. Many important papers have 

 been issued by the English Board, such as 

 Masterman's report on the plaice fisheries of tlie 

 North Sea, and the age, growth, and sexual maturity 

 of this fish ; Todd on the food of the plaice ; Buchanan 

 Wollaston on the spawning grounds of the plaice; 

 Wallace on the age and growth-rate of the plaice, on 

 the ear-bones, and on the size and age of the plaice 

 at maturity; whilst others by Booley, Lee and 

 Atkinson, Garstang, Bygrave, and Matthews show 

 the scientific zeal of the Board's staff. The excel- 

 lent work in marine zoology and in the fisheries 

 which for more than thirty years has been carried on 

 by the Marine Biologicpl Association at Plymouth like- 

 wise speaks for itself. 



The work of the northern section, as undertaken 

 by the Fishery Board for Scotland, has also been 

 reviewed up to 190*7 in the second lecture at the Royal 

 Institution. It was shown that, as a result of Hjort's 

 discovery of vast swarms of young Gadoids from Jan 

 Meven southwards, there was little need for surprise 

 at the immense hordes of young haddocks which, 

 as last year, swarmed all along the east coast of 

 Scotland,' and as little need for doubting the resources 

 of Nature in the sea. 



Jobs. Schmidt gives valuable information on^ the 

 voung stages of the cod tribe, of the lings, halibut, 

 long rough dab, and the torsk, and, along with 

 Petersen, describes the spawning ground of the eel 

 in mid-.'Vtlantic. H. M. Kyle produces two papers on 

 the literature of the ten principal food-fishes of the 

 North Sea and a catalogue of the fishes of northern 

 Europe. Jensen (Norway) writes on the ear-bones of 

 fishes from the bottom of the deep polar sea, and 

 shows that cod may frequent the upper regions of the 

 water and thus be overlooked. Johansen describes the 

 history of the post-larval eel, and Petersen writes on 

 the larval and post-larval stages of the ling, flat-fishes, 

 eel, and on the fisheries of the Cattegat and Sweden. 

 On the whole, the papers on the young stages of the 



