trawlers. Both methods of fishing catch a few halibut and certain edible fishes which are not marketed. The haddock and the cod are the principal species sought, and were it not for these the bank fisheries would not exist under present economic conditions.

Both of these fish are bottom feeders, and while they feed to some extent on young or small fishes, their diet consists principally of invertebrates such as constitute the bottom fauna of the banks. They all sometimes contain pieces of herring and similar fishes, but there is good reason to believe that in most cases these are baits taken from the lines. Most of the food consists of echinoderms (starfishes, brittle stars, sea urchins, and sea cucumbers; lamellibranchs (scallops, mussels, and other bivalves); gasteropods (various snail-like mollusks); crustaceans (crabs and shrimps); and annelids (worms). Although these fishes spawn on some of the banks, they resort to them primarily for food; and there is no doubt that if the bottom. growth were destroyed the productiveness of the fishing banks would be seriously impaired if not destroyed, and it is therefore important to the present inquiry that the methods of fishing now pursued should be considered in relation to their effects on the denudation of the bottom.

In this respect the trawl-line fishery is innocuous and need not be discussed, but the otter trawl operates in such manner as to raise a valid assumption against it and to demand a critical examination of its effects. As the otter trawl, as a whole, sweeps over an area of about 80 acres at each haul and many square miles in the course of a year's fishing, the assumption has been that its effects on the bottom growths of necessity must be disastrous; and the observers on the steamers were instructed particularly to note the quantity and character of the bottom materials brought up. Most of the sand, broken shells, and other fine material not bound together by worm tubes, etc., undoubtedly would wash through the mesh and would not figure in the load landed on deck, but a large part of the bottom growth, which, and not the bottom itself, is the important factor in the present inquiry, would come up in the trawl.

Much of the data submitted by the observers are too vague for quantitative consideration, but one man definitely states the quantities in bushels in his monthly analysis of the results of his observations on each bank. From his returns it is deduced that the average quantity of scallops, clams, shells, sponges, starfishes, and bottom material generally, varied with the month and the locality, from a small fraction of a bushel to 4.7 bushels per haul, the latter being the average of 26 hauls made in South Channel in August, 1913.

A simple computation shows that this maximum represents a film. 0.00024 inch in thickness spread over the area swept by the trawl, or, to state the case in another way, a little pile of material 1 foot

square and 9 inches high on each acre traversed. This means either that a small proportion of the existing bottom material was captured by the net, which is probable, or that there was very little material to take. In either case the result to the fishery is trivial and negligible, as the whole quantity, shells and all, if eaten by the marketable haddock and cod alone taken in the same hauls would constitute a morsel of but about 2 cubic inches for each-a very small meal, indeed-and leave nothing for the many other fishes taken at the same time.

But, the evidence shows, this material was not destroyed but thrown overboard when the decks were cleared after each haul, the uninjured organisms in large part to carry on their lives as before, and the dead shells to lie again on the bottom and serve as places for attachment for other growths. Any crushed scallops, mussels, etc., undoubtedly would be eaten by fishes or by animals on which the fishes feed, for no dead organic matter is permitted to lie long unutilized on the floor of the sea. Fragments of sponges would each begin to grow into a new sponge, and mutilated starfishes would soon reproduce the injured or lost parts, if they did not fall prey to the fishes in the meantime. This modicum of captured and liberated material would therefore be little if any diverted from the function which it would have discharged if it had remained unmolested on the bottom. It is claimed, however, that but part of the damage wrought to the bottom by the trawls is represented by the material brought up in the nets, greater quantities of the bottom organisms being torn loose, crushed, and mutilated. To the extent that this may be true, the preceding remarks on the utilization of the detached and injured organisms also apply. It is, of course, impossible to observe the action of trawls operated in depths as great as are found in the bank fisheries, but by an examination of the catch, the method of operating the apparatus, and comparison with the known effects of similar appliances, conclusions of some value may be deduced.

There are three parts of the otter trawl which scrape the bottom: The boards, the foot line, and the net itself. The boards each weigh about 1,500 pounds in the air or about 900 pounds in the water, and as they are 12 feet long and 2 inches thick they bear on the bottom with a pressure of a little less than 3 pounds to the square inch. This is a little less than the standing pressure of an average man. When the net is fishing, the otter boards are set with the short sides vertical and their long sides at an angle of about 20 degrees or less to the direction of motion, and as they are 12 feet long each scrapes a strip about 4 feet wide. As the average haul of an otter trawl is about 6 miles, the two boards scrape on each haul a surface of about 6 acres. An average of about 35 hauls was made on each trip observed, and on this basis it is computed

that on the 326 trips made by the steam trawlers in 1913 the boards alone scraped about 115 square miles of the bottom, provided they were in constant contact.

The footline or ground rope forms the front border of that part of the net lying on the bottom. It stretches in a curve between the otter boards, is about 140 feet long, and 3 to 4 inches in diameter. It is composed of a core of steel wire rope about 1 inch in diameter, heavily served with marlin and rope partly to protect the wire from chafing, but principally to prevent undue cutting into the bottom. The ground rope weighs about 800 pounds in the air, but as rope is but little heavier than water and the wire weighs not over 150 or 160 pounds, it is certain that when at rest it does not exert a pressure in excess of 2 pounds per linear foot.

The ground rope sweeps over a strip about 100 feet wide, and using the same data employed in the discussion of the otter boards this would cover an area of about 73 acres per haul and about 1,300 square miles for all hauls made by the steam trawlers in 1913. The net with its chafing gear, a device of old netting to minimize abrasion on the bottom, weighs about 800 pounds in air, but very little in water. As fish weigh but little more than water, the catch adds nothing to the pressure of the net on the bottom unless it includes stones, sand, shells, and other heavy materials. The net, being attached to and following the ground rope, sweeps over the

same area.

The otter boards, by virtue of their inclined position to the line of draft through the water, act, when resting on the bottom, like the scraper of a road machine, such material as they dislodge or tear loose passing backward and inward toward the net. As the purpose of the boards is to spread the net laterally, no useful purpose is served by permitting them to plow deeply, and the ideal practice is to have them skim over the bottom as lightly as possible. The drag of the towing warps, inclining upward toward the vessel, tends to lift the boards, especially at the forward ends, and this tendency increases with the speed at which they are towed and, at any given depth, inversely with the length of warp paid out. With the speed too great or the warp too short, the boards and with them the net may be lifted quite clear of the bottom. A slight lifting of the boards is permissible and perhaps desirable, but if the ground rope raises materially, the efficiency of the net is impaired.

There are two instruments employed in fisheries in other parts of the world for taking bottom growths, the effects of which are comparatively well known, and a consideration of these, by analogy, may be of some assistance in the formulation of an opinion as to the effects of the otter trawl. One of these is the dredge extensively eniployed in the oyster fishery. This consists of a short chain bag

or net, attached to a rectangular steel frame, about 4 feet on its long sides. The average weight of these dredges is about 150 pounds, and the long sides of the frames are provided with 15 or more long, steel teeth which dig into the bottom as the instrument is dragged over the beds. They are designed especially to tear the oysters from the bed, and incidentally they bring up sponges, starfishes, mussels, and other bottom organisms.

It is estimated on good data that in Maryland the dredging vessels in the course of the season's work cover with their dredges an area equal to about three times that of the oyster beds, or, in other words, an average acre or square mile is scraped three times in the course of the year. These beds have been intensively dredged annually for many years, and while some of them have been depleted, they are still producing large quantities of oysters wherever care has been exercised to return to the beds all shells and small oysters. Where the beds have been depleted it is in nearly every case due to neglect to comply with the requirements of the law in this respect.

The other implement to which reference was made in a preceding paragraph is the gaugava, a peculiar type of dredge trawl used in the Mediterranean sponge fisheries. It consists of a short bag net of heavy twine attached to a rectangular frame about 35 feet long and 2 feet high. The lower side and about half of the two ends is composed of an iron bar 2 to 3 inches in diameter weighing about 600 or 700 pounds, and the top of the frame is a wooden bar 5 or 6 inches in diameter. This implement is towed at a speed of about 1 to 14 miles per hour, and the length of the towing warp is so adjusted that the iron bar scours the bottom without burrowing. The purpose of the gaugava is to tear commercial sponges from their firm attachments to the bottom and incidentally it brings up all other bottom growths. It is undoubtedly the most destructive method of sponge fishing, as it tears from their attachment many commercial sponges too small for the market which would be valuable if permitted to become a year or two older. Yet 150 vessels are using this appliance on the coast of Tunisia, and while the beds have been depleted to some extent and require occasional periods of recuperation, they are after many years still profitably productive. Now both the oyster dredge and the gaugava are designed for tearing up and capturing the bottom growth, they are employed in a way to accomplish that purpose, and a large part of the material captured is not returned to the water. Each of them is much heavier than the ground rope of the otter trawl, the dredge weighing in water about 30 to 35 pounds to the linear foot, the gaugava about 15 pounds, and the footrope of the trawl less than 2 pounds.

The footrope of the trawl is of larger diameter than the frames of the other two implements, and, moreover, it is covered with rope, a cushioning material, while the others are bare steel. It is evident that if it were towed at the same speed as the oyster dredge and the gaugava it would do much less damage owing to its comparatively small weight per foot, but it is dragged at a much higher speed than the oyster dredge and at about three times the speed of the gaugava, which it more closely resembles. With the same length of warp, dredges and trawls touch the bottom more lightly the higher the speed at which they are towed, and at the same speed the lighter and more bulky gear lifts more freely than the heavier and more compact. That the otter trawl catches an insigificant quantity of bottom material as compared with the oyster dredge and the gaugava has been shown by direct observation, and that it does a negligible amount of damage not observable is clear from a comparison of the construction and methods of operation of the three types of apparatus and a consideration of the fact that years of intensive operation of the dredge and gangava have by no means destroyed, although they have to some extent depleted, the beds on which they work, especially when recklessly used. The only parts of the otter trawl which have sufficient weight to effectively scrape the bottom of its attached organisms are the boards, and they cover but about 10 per cent of the sweep of the net and undoubtedly are much of the time largely and part of the time wholly supported by the draft of the towing warps.

It is believed, therefore, that denudation of the bottom is not a momentous factor in any injury which may be wrought to the fisheries by the otter trawls.

DESTRUCTION OF SPAWN BY OTTER TRAWLERS.

The allegation sometimes made that the otter trawl destroys the spawn of food fishes can be dismissed with a simple negation. The eggs of all of the important food fishes of the New England coast and the banks, except the herring, are pelagic; that is, they float at or near the surface.

The only destruction of spawn is that involved in taking spawning fish, and such fish are alsò taken on hand lines on Georges Bank at least and by nets along the coast.

INTERFERENCE OF THE OTTER TRAWL WITH OTHER FISHERIES.

The observers on the vessels were instructed to make note of all cases in which lines or other fishing gear were destroyed or interfered with by the steam trawlers. Very few cases of such destruction or interference were noted.

Mr. Walter H. Rich, who served from June to November, inclusive, most of the time on steam trawlers, but who made a number of