480.5; at the former for April, 45°.6, 50°, 54°.5, 550.7; for November, 540.2, 520.1, 50°, 47°. At Norfolk the averages for the last half of March are 48° and 50°. The movements of the menhaden in other waters have not been very carefully observed, but we know that they enter the Potomac late in March and early in April, and that they linger till the last part of November. In 1874 the young menhaden lingered in the Lower Potomac until the middle of December. In 1876 the average for December surface temperature at Norfolk was 360.8, for bottom temperature 360.4. In 1874 the surface average for December at Norfolk was 43°, or 60.4 higher than in 1876, the year from which our tables of observations are made up. The average for Norfolk surface temperature in November was, in 1876, 530.4, in 1874, 550.1 or 10.7 higher. It is quite probable that in 1874 the water of the Lower Potomac did not become colder than 50° until December. At Wilmington the monthly means of bottom temperature in 1876 and 1877 were for December, 430.1, January, 43°, February, 48°.5; in 1874 and 1875, December, 480.1, January, 430.8, February, 450.5. December, 1876, was unusually cold, the mean temperature of the air being 460.3, against 590.1 for the same month in 1874. January and February of 1874 were relatively cold, their air temperature being 480.1 and 530.1, against 570.1 and 520.5 in 1876. The surface quarter-month averages for the last half of February, 1877, are 490.1, 500.5; for the first half of March, 1876, 520.6, 570; for late November and early December, 1876, 570.1, 5306, 460.6, 450.3. No observations have been made upon the movements of the menhaden at Wilmington. At Beaufort, 30 miles farther north, they appear to be absent during the winter. It is much to be regretted that there are no temperature observations from Cape Hatteras. The relations of this locality to the Gulf Stream are peculiar, and corresponding peculiarities in the temperatures no doubt exist. The hundred fathom curve is distant about 40 miles from the point of the cape, and the average summer limits of the Gulf Stream, as laid down upon the British Admiralty charts, extend nearly into this curve. The observations made at Wilmington, situated as it is in a bend of the coast, at least 100 miles from the summer limits of the Gulf Stream, and at the mouth of a river which rises 200 miles away in the elevated central portion of North Carolina, can hardly be taken as criteria of the temperatures of Cape Hatteras. This is still more unfortunate from the fact that the movements of the menhaden, bluefish, "sea trout," and other warm-water species are very peculiar at this point. It will be strange if the monthly mean of water temperature for Cape Hatteras in December, and perhaps January, does not prove to be more than 50°. Savannah is at least 120 miles from the Gulf Stream, and its means for December and January, 1876-1877, as well as those of Charleston, are below 500. Charleston water appears to be uniformly warmest. In 1874, December in Charleston averaged 48°.8; in 1875, January averaged 50°.2. The movements of the menhaden in this region have not been observed, but since in the north it is not more hardy than the shad, and since the shad do not venture into the Georgia and Carolina rivers in December, it is safe to predict that the habits of the menhaden are similar. Jacksonville, Fla., is the only point on the east coast from which there are observations showing a temperature unformily above 51°, and here the menhaden remain throughout the winter. Maximum limits of temperature.-On the coast of Eastern Maine we are told that the menhaden schools keep passing to the eastward until about the middle of July, when their impetus is apparently checked and their movements for thirty or forty days seem to be local only. During this period the temperature at Portland ranges from 600 to 70°, this being the height of mid-summer. The monthly means for July and August, 1876, were 660.7 and 630.9. The same months at New London are placed at 730 and 730.3; at Norfolk, 840.1 and 780.3. Wilmington, Charleston, and Savannah do not range much above Norfolk; June, July, and August at Jacksonville average above 85°, and we have no satisfactory evidence that the menhaden are seen there in mid-summer. At Key West the lowest monthly mean is December, at 6C0.4, in an unusually cold winter. Preferred range of temperature.-These facts appear to indicate that under ordinary circumstances the menhaden prefers a temperature of 60° to 70° Fahrenheit. When the rising temperature of spring has passed the limit of 50° to 51° the fish are certain to appear, and when the falling temperature of autumn reaches that point their departure is equally sure, though a few individuals may linger in waters not congenial to them. The opposite limit seems to be marked by the line of 80° or perhaps 75°. An easterly or northerly wind, lowering temporarily the surface temperature, causes the schools to sink below the surface, as is shown in paragraph 95. The chill of night also drives them down. These conclusions are not to be regarded as final. The movements of the fish about Cape Hatteras are very puzzling and need to be interpreted by a series of careful temperature observations. It is a well-established fact that the summer of 1877 was not so warm as that of the preceding year. It is also known that the catch of menhaden in Maine for that year was much smaller than in 1876, when it was unusually large. There may be a connection between these circumstances, though the observations of water temperatures at my disposal are not sufficient to warrant decided generalization. The means for the summer months of 1876 were, at Eastport, 450.5; at Portland, 570.9; at Wood's Holl, 700.4; at New London, 68°; at Norfolk, 780.7. The corre sponding means for 1877 were, at Eastport, 420.8; Portland, 570.6; Wood's Holl, 670.7; New London, 66°.9; and Norfolk, 770.2. The summer of 1877 was then colder than that of 1876 by 20.7 at Eastport; by 00.3 at Portland; by 20.7 at Wood's Holl; by 10.1 at New London; and by 10.5 at Norfolk. July, 1877, was colder than July, 1876, at Eastport by 20.8; at Portland by 20.2; at Wood's Holl by 50.9; at New London by 10.2. August, 1877, was colder than August, 1876, at Eastport by 0°.3; at Portland by 00.6; at Wood's Holl by 0°.9; at New London by 30.1. September and October of 1877 were warmer than the corresponding months of 1876 at Portland, and this agrees with the fact that the catch of menhaden in Maine was entirely made in the fall months. General discussion as to the winter habits of summer fishes. 86. The relations of the temperature of the water to the movements of the menhaden schools having been studied, a new question is at once sug gested. When the schools disappear from our coast, driven by falling temperature, where do they go? The answer must be in the form of a theory, for no one has seen them during their winter absence; at least no one has been able to identify the New England and Middle States fishes after their departure in the autumn. It is evident that there are but three courses open to our coast fishes when it becomes necessary for them to leave inshore (1.) They may swim out to sea until they find a stratum of water corresponding in temperature to that frequented by them during their summer sojourn on our coast. (2.) They may swim southward until they find water of the required warmth. (3.) They may descend into the abyssal depths of the ocean, there to remain for a season in partial or total torpidity. The last of these theories is the least plausible, from the fact that it necessitates the greatest change in habits. The susceptibility of the menhaden to slight changes of temperature has been pointed out. Hibernation in the oceanic depths involves a change to a temperature 100 to 250 colder than that preferred by them in summer, as well as other important changes in respect to specific gravity and pressure. The theory of hibernation discussed with special reference to the habits of the mackerel. 87. The hibernation theory is a favorite one with the fishermen of the British Provinces, and has recently received strong support from Professor Hind, in his treatise on the fisheries of North America. His arguments refer to the mackerel, although the scup, tautog, and herring are included by implication. He refers to the appearance of the mackerel "with scales on their eyes and blind," and suggests that the winter sleep of fishes is probably much more general than is usually supposed. He takes the position that there are only two alternatives possibly open to fishes which cannot live in cold water. They must migrate south or hibernate. His arguments naturally fall into two categories—those against migration and those in favor of hibernation. Those in favor of hibernation may be summed up as (1) the testimony of fishermen and travelers; (2) the quoted opinions of theorizers; (3) the alleged hibernations of other fishes; and (4) peculiarities in early and late fish. (1.) The statements of one M. Pleville le Peley, "an eye-witness," are quoted both from Lacepede and H. de la Blanchere. M. le Peley gravely states that he had observed about the coasts of Hudson's Bay "the mud at the bottom of the small clear hollows incrusted with ice round their coasts, entirely bristled over by the tails of mackerel imbedded in it nearly three parts of their length," and again "affirms having seen in the middle of winter, in deep muddy bottoms, myriads of mackerel, packed close one against the other, with one-half of the body plunged in the mud, where they remained during the winter. As soon as spring came they aroused themselves from their torpor, and appeared always on the same day on the same coast at the surface of the sea, and repaired to favorable spots to spawn." The absurdity of these statements renders it unnecessary to criticise them. The other testimony is less definite. A Newfoundland fisherman remembers to have heard his father say that forty years before "he had often seen mackerel in White Bay come on shore like squid, with scales on their eyes and blind, about Christmas." And, again, a statement quoted from the Rev. John Ambrose, that "mackerel have been brought up from the muddy bottoms of some of our outer coves by persons spearing for eels through the ice,"§ which statement is not supported by the personal evidence of Mr. Ambrose, being merely a hearsay story. And this is all. Professor Hind, in Part II of the same work remarks confidently: "That the mackerel spends the winter months in a torpid condition near to the locality where the schools first show themselves on the coast has already been adverted to," and again refers to "the fact, already noticed, that it is taken in winter from muddy bottoms." I submit that no such fact has been established and that Professor Hind's generalizations are without foundation. There is much better evidence to prove that swallows hibernate in the mud of ponds, a theory which has had numerous advocates since the time of Gilbert White, of Selborne. (2.) Professor Hind first quotes from "La Peche et Les Poissons" of M. H. de la Blanchere. The statement, printed as it is in a single paragraph instead of two and not given in full, conveys the impression that M. de la Blanchere indorses the views of Pleville le Pcley, already quoted. On the contrary, he states explicitly: "The question of the annual and * Hind, op. cit., Part II, p. 10, note. + Part I, p. 78. Part I, p. 78. § Observations on the Fishing Grounds and Fish of St. Margaret's Bay, N. S., by Rev. John Ambrose. <Proceedings and Transactions of the Nova Scotian Institute of Natural Sciences, 1866-'67, quoted by Hind, op. cit., Part I, p. 79. IP. 10. regular appearance and disappearance of this fish is still unsolved." He then proceeds to contrast with M. le Peley's views those of Duhamel de Monceau, Anderson and others, who represented that the mackerel pass the winter in the northern seas, and in spring, beginning their migrations, pass southward visiting first Iceland, then Jutland, then Scotland, and Ireland, and the coasts of Continental Europe, in autumn assembling together for a return to the polar regions. Then he quotes Pleville le Peley, and remarks: "This theory associates the mackerel with many other sedentary fishes which pass the winter at the bottom of the sea, stupefied by the cold into a kind of lethargy, and would serve to explain why, in October, young mackerel of 10 and 15 millimeters are taken, why in winter others of larger size are taken, not with a line, but with nets, which entangle those which had not already buried themselves in the mud or the sand."* Another quotation is made † from Shaw's "General Zoology, or Systematic Natural History," published in 1803. Professor Hind says that "the four disputed points in relation to the natural history of this fish are there asserted, namely, its local habits, its torpidity during hibernation, the film over the eye, and the fact of its being partly imbedded in the soft mud or sand during its winter sleep." I admit that Shaw asserts the presence of a film over the eye. He does not, however, even give the theory of hibernation his personal indorsement, but remarking that the long migration of the mackerel and herring seems at present to be called in question, continues, "It is thought more probable that the shoals which appear in such abundance round the more temperate European coasts, in reality reside during the winter at no very great distance, immersing themselves in the soft bettom, and remaining in a state of torpidity, from which they are awakened by the warmth of the returning spring, and gradually recover their former activity." Even if Shaw could fairly be quoted as a supporter of this theory, his opinion is of little value. He was not a naturalist, but a bookmaker, and his compilations are acknowledged to be inaccurate. ‡ The opinions of Dr. Bernard Gilpin and the Rev. John Ambrose, two excellent Nova Scotian observers, are quoted, § though with no apparent reason, for the latter remarks only that "it is the opinion of some that the third run of mackerel, which takes place at St. Margaret's Bay about the first of August, are not returning from the Gulf of Saint Law rence, but from sea, and it may be that a portion of the immense schools passing eastwardly in the spring strike off to some favorite bank * Nouveau Dictionnaire Général des Peches, &c., par H. de la Blanchere. Paris, 1868, p. 183, article Maquereau. t Hind, op. cit., Part II, p. 10. See a criticism upon Shaw's General Zoology in Gill's Arrangement of the Families of Fishes, &c.,. 1872, pp. 40, 41. § Part I, p. 79. |