SUMMARY, EAST COAST OF SCOTLAND.

On the east coast of Scotland demersal fishes and round fishes both showed a continuous increase in the quantities landed from 1891 to 1912, and flat fishes increased until 1901, after which they decreased. These increases are due largely, if not wholly, to the development of steam trawling, which was responsible for about 25 per cent of the catch in 1891, 75 per cent in 1901, and about the same in 1912. The total catch of the trawlers, therefore, follows the same course, although the increases are heaviest between 1891 and 1901, when the fleet was developing most rapidly.

Neither the average length of the voyages nor the number of days' absence in the several years are known, and the only basis for the determination of the catch per unit of effort is the catch per annum. per trawler. With some fluctuations this has shown an increase in respect to both demersal fishes as a whole and round fishes, and an almost continuous and material decrease in flat fishes. As has been shown elsewhere, this does not furnish a very satisfactory basis for comparison, as the effects of vessels lying idle for indeterminate and possibly important periods are not eliminated.

As in England, cod, haddock, and plaice are the most important species, and of these the latter is recorded in combination with two other species, neither of which, however, is quantitatively of much relative importance. Of these the cod has almost continuously increased in the average catch per vessel, and the net gain from 1891 to 1912 was large. The haddock has fluctuated, but in most years the average catch per vessel was higher than in 1891, although a heavy fall in 1912 caused a net decrease of 41 per cent for the entire period. The plaice, including the flounder and the brill, has decreased almost continuously, and the catch of 1912 was but 14 per cent of that of 1891. At a few ports where the number of landings has been given in later years, the average catches per voyage in 1912, as compared with 1906, showed an increase of 10 per cent in cod, a decrease of nearly 22 per cent in haddock, and a decrease of 17 per cent in plaice. As to the proportions of the several sizes of these fishes, data are available for the landings at Aberdeen, whence hail the majority of the trawlers, but for recent years only. The catch on the "east coast grounds" in near-by portions of the North Sea exhibited an increase in the proportionate quantity of the small sizes of all three species. From the region of Orkney and Shetland, on the northwest border of the North Sea, large cod and plaice decreased proportionately to the whole, while large and medium haddock increased somewhat. While all of the foregoing applies to fish landed on the east coast of Scotland from all regions, most of them came from the North Sea, concerning which, it may be said, there

fore, that there is strong evidence of a depletion of the plaice and some evidence of a falling off in the haddock, the two most distinctly trawl-caught fish.

SUMMARY AND CONCLUSIONS.

1. Otter trawls do not destroy the spawn of the commercially important demersal fishes, all of which have pelagic or floating eggs. 2. Otter trawls do not seriously disturb the bottom over which they are fished nor materially denude it of the organisms which directly and indirectly serve as food for commercial fishes.

3. The investigations conducted by the Bureau of Fisheries indicated that during 1913 trawling interfered but little with line fishing and caused practically no damage to the trawl lines. From the nature of the two fisheries, however, it is believed both can not be extensively conducted on the same grounds without resultant accidental damage to or interference with the lines, especially in foggy weather.

4. Otter trawls as compared with lines take a much larger proportion of commercial fishes too small to market. From January to May 3 per cent of the cod and 11 per cent of the haddock, and from June to December 40 per cent of the cod and 38 per cent of the haddock were unmarketably small, while the lines caught practically no such fish. These proportions were fully maintained in the respective classes of vessels fishing at the same season on the same grounds. These young fish are practically all destroyed.

5. Otter trawls as compared with trawl lines market a much larger proportion of small fish, and, therefore, they not only destroy more small fish not utilized, but are biologically more wasteful, by reason of the smaller size of the marketable fish. As, however, a large proportion of these smaller fish would undoubtedly die or be destroyed under natural conditions before reaching the large or medium size, the effects on the total supply of fish are less to a conceivable, but at present indeterminable, degree than the data presented would indicate.

6. Practically the only food fish which the otter trawl has added to the present yield of the fisheries on the banks is the "sole," of which about 600,000 pounds were caught in 1913. This is equal to about three times the quantity of hake, 36 per cent of the cod, and 5 per cent of the haddock, or about 4 per cent of the three combined marketed by the trawlers. On the other hand, it is estimated that this is less than one-third of the weight of the immature cod, haddock, and hake destroyed by otter trawls. The trawlers have not added greatly to the food supply by the introduction of fishes not previously taken in quantities by the liners. They may have conferred some benefit on the consumer by catching and marketing

larger quantities of the smaller and cheaper fishes of the cod family, provided, of course, that this does not induce the depletion of the ultimate supply. Both trawlers and liners catch considerable quantities of edible species for which they have failed to develop a market.

7. There is but little evidence to show that the introduction of the otter trawl in the American fisheries has had any material effect in keeping down the price of fish. Since 1898 there has been a gradual, although fluctuating, increase in the price received by the fishermen for all kinds of fish. The haddock has increased proportionately less than the other demersal fishes and since 1908 has kept close to or below the level of that year, and this is probably, to no small extent, due to the large quantities of small and cheaper fish landed by the trawlers. The catch of the American trawlers, however, is too small in proportion to the total production of demersal fisheries to have a material effect on prices, and we have therefore examined the price statistics of England to determine what light they shed on the subject. We find that while, apparently, the otter trawl reduced the cost of production of fish for a number of years after it become paramount in the fishery of that country, it did it to some extent by reducing the standards of size, and that recently there has been a rapid increase in the prices of fish which are now higher than ever. Undoubtedly the general increase in commodity prices has had some effect.

8. We have been unable to discover from the examination of official records, extending from 1891 to 1914, any evidence whatever that the banks frequented by the American otter trawlers are being depleted of their fishes. Since 1905 when the first steam trawler began operations off the New England coast there have been fluctuations in the total yield of the bank fisheries, but they have been no more violent nor significant than in the period before 1905 when lines alone were used. In fact, some of the heaviest yields recorded in the line fishery have been made in years since the otter trawl was introduced, and, while the catch of line fishemen in 1914 on Georges Bank, South Channel, and Nantucket Shoals, where the otter trawlers operate, was less than half of that in the extraordinary year 1905, this was accompanied by a proportionate reduction in the intensity of the fishery as measured by the number of trips to these grounds. The average catches per trip of haddock and of cod, haddock, and hake combined have been considerably higher since 1910 than for any similar period of which we have record. The average catch of cod per trip to these banks has decreased since 1910, but it is higher than for any similar period prior to the introduction of otter trawling. As the liners catch, proportionately, more cod and the trawlers more haddock on these banks, and as quantitatively the liners catch

H D-63-3-vol 104-7

more of each, the statistical facts of the fishery certainly do not indicate that it has yet shown signs of depletion from the use of the otter trawl,

9. We recognize that the conclusions arrived at in the preceding section are necessarily inconclusive for the reason that the ottertrawl fishery in American waters is too recently established and relatively too small to have had a very material effect on the fish supply of the banks frequented. We have therefore examined the accessible data relating to the fishery in England and Scotland, particularly that conducted in the North Sea, where it is most intensive and has been longest established. We have used the data without reference to the opinions others have expressed and have endeavored to arrive at independent conclusions without prejudice from previous investigations of the subject. While the statistical information, particularly that contained in the English reports, is more useful for the purpose than is that pertaining to our own fishery, it is in recent years only that it is given in sufficient detail. Proof respecting the depletion of the fisheries, on the contrary, can not be deduced. The most possible has been the establishment of more or less strong presumptions one way or the other.

10. The cod, haddock, and plaice are the most important and abundant of the demersal fishes of the North Sea, and the three combined comprise about 75 per cent of the catch. English vessels take between 50 and 60 per cent of the total of these species landed from the North Sea, and the English trawlers alone take from 45 to 50 per cent. These three fishes are, therefore, the only ones which it is important to consider.

The statistical data of the English fisheries indicate by a decrease in the total catch, in the average catch per unit of effort, and in the proportion of large fish to the total that probably the plaice fishery is being depleted. The first two criteria also point to a decrease in the haddock, and it is believed that the third test fails to do so only because a lowering in the standard of sizes makes the statistics in this particular misleading. The cod does not show indications of overfishing, probably because its different habits make it less vulnerable to the effects of the predominant fishery, steam trawling.

The statistics of Scotland are less satisfactory for our purpose than are those of England, and it is not possible to obtain sufficient separate data for the North Sea. We have therefore considered the fuller information obtainable in respect to the east coast, the fishery of which is prosecuted mainly in the North Sea. The same three species are discussed, the catch of these by Scotch vessels in the North Sea proper constituting about 25 per cent of the total yield of the three in that sea. The plaice show signs of depletion

in the heavy decrease of the total yield and of the average catch per vessel and in the proportion of large fish to the smaller sizes. While the haddock has increased in the total catch, the average catch per vessel has fluctuated to an extent which makes any deductions from the data uncertain; and there is a small decrease in the relative proportion of large fish compared with the total. The cod has increased in total catch and in the average catch per vessel, but relatively fewer larger fish were taken in later years.

Considering the English and Scotch fisheries in the North Sea together, there is a strong presumption of overfishing in the case of the plaice, considerable evidence of the same thing in respect to the haddock, and practically none concerning the cod. As the steam trawler is overwhelmingly predominant in the fisheries for these species, it must be held responsible for such overfishing as may have occurred.

11. Three regions other than the North Sea support more or less important English trawl fisheries yielding essentially the same species which have been discussed. They are Iceland, the White Sea, and the Faroe Islands. Separate data concerning them are available for years subsequent to 1905, and while the period covered is too short to admit of deductions of much value, it has been employed for purposes of comparison with the North Sea.

In Iceland the total catch of both haddock and plaice and the average catch of each, especially the latter, showed heavy decreases, while the cod increased. In all species, but particularly the plaice, there was a decrease in the proportion of large sizes to the total.

In the White Sea the total catch of all species increased from 1906 to 1912, but this was in part due to an increase in fishery activity. As measured by the quantity caught per trip there was an enormous increase in cod, a heavy increase in haddock, and a heavy decrease in plaice. The proportion of large fish was approximately maintained in the cod and plaice but was much smaller in later years in the case of the haddock, thus indicating that the increase in the catch of that species was due to the saving of smaller fishes previously discarded or unsought.

In the Faroes there was a slight increase in the average catch of cod per trip, owing mainly to an increase in the smaller sizes, and a decrease in the haddock, accompanied by a similar increase in the take of smaller fish. The catch of plaice was negligible in all years.

The data from these regions are therefore in general confirmatory of those relating to the North Sea, namely, that there is a presumptive decrease in the plaice, a probable smaller decrease in the haddock, and little or no change in the numbers of cod.