The Harvest of the Sea / A contribution to the natural and economic history of the British food fishes

by James Glass Bertram

SMOLT TWO YEARS OLD.
Half the natural size.

It is pleasant, rod in hand, on a breezy spring day, while trying to coax “the monarch of the brook” from his sheltering pool, to watch this annual migration, and to note the passage of the bright-mailed army adown the majestic river, that hurries on by busy corn-mill and sweeps with a murmuring sound past hoar and ruined towers, washing the pleasant lawns of country magnates or laving the cowslips on the village meadow, and as it rolls ceaselessly ocean-ward, giving a more picturesque aspect to the quaint agricultural villages and farm homesteads which it passes in its course. During the whole length of its pilgrimage the army of smolts pays a tribute to its enemies in gradual decimation: it is attacked at every point of vantage; at one place the smolts are taken prisoners by the hundred in some well-contrived net, at another picked off singly by some juvenile angler. The smolt is greedily devoured by the trout, the pike, and various other enemies, which lie constantly in waiting for it, sure of a rich feast at this annually-recurring migration. But the giant and fierce battle which this infantile tribe has to fight is at the point where the salt water begins to mingle with the stream, where are assembled hosts of greedy monsters of the sea of all shapes and sizes, from the porpoise and seal down to the young coal-fish, who dart with inconceivable rapidity upon the defenceless shoal and play havoc with the numbers.

Many naturalists dispute most lustily the assertion that the smolt returns to the parental waters as a grilse the same year that it visits the sea; and some writers have maintained that the young fish makes a grand tour to the North Pole before it makes up its mind to “hark back.” It has been pretty well proved, however, that the grilse may have been the young smolt of the same year. A most remarkable fact in the history of grilse is, that we kill them in thousands before they have an opportunity of perpetuating their kind; indeed on some rivers the annual slaughter of grilse is so enormous as palpably to affect the “takes” of the big fish. It has been asserted, likewise, that the grilse is a distinct fish, and not the young of the salmon in its early stage. There has been a controversy as to the rate at which the salmon increases in weight; and there have been numerous disputes about what its instinct had taught it to “eat, drink, and avoid.”

It has been authoritatively settled, however, that grilse become salmon; and, notwithstanding a recent opening up of this old sore, I hold the experiments conducted by his Grace the Duke of Athole and the late Mr. Young of Invershin to be quite conclusive. The latter gentleman, in his little work on the salmon, after alluding to various points in the growth of the fish, says:—“My next attempt was to ascertain the rate of their growth during their short stay in salt water, and for this purpose we marked spawned grilses, as near as we could get to four pounds weight; these we had no trouble in getting with a net in the pools below the spawning-beds, where they had congregated together to rest, after the fatigues of depositing their seed. All the fish above four pounds weight, as well as any under that size, were returned to the river unmarked, and the others marked by inserting copper wire rings into certain parts of their fins: this was done in a manner so as not to interrupt the fish in their swimming operations nor be troublesome to them in any way. After their journey to sea and back again, we found that the four pound grilses had grown into beautiful salmon, varying from nine to fourteen pounds weight. I repeated this experiment for several years, and on the whole found the results the same, and, as in the former marking, found the majority returning in about eight weeks; and we have never among our markings found a marked grilse go to sea and return a grilse, for they have invariably returned salmon.”

The late Duke of Athole took a considerable interest in the grilse question, and kept a complete record of all the fish that he had caused to be marked; and in his Journal there is a striking instance of rapidity of growth. A fish marked by his Grace was caught at a place forty miles distant from the sea; it travelled to the salt water, fed, and returned in the short space of thirty-seven days. The following is his entry regarding this particular fish:—“On referring to my Journal, I find that I caught this fish as a kelt this year, on the 31st of March, with the rod, about two miles above Dunkeld Bridge, at which time it weighed exactly ten pounds; so that, in the short space of five weeks and two days, it had gained the almost incredible increase of eleven pounds and a quarter; for, when weighed here on its arrival, it was twenty-one pounds and a quarter.” There could be no doubt, Mr. Young thinks, of the accuracy of this statement, for his Grace was most correct in his observations, having tickets made for the purpose, and numbered from one upwards, and the number and date appertaining to each fish was carefully registered for reference.

As the fish grew so rapidly during their visit to the salt water, people began to wonder what they fed on, and where they went. A hypothesis was started of their visiting the North Pole; but it was certain, from the short duration of their visit to the salt water that they could proceed to no great distance from the mouth of the river which admitted them to the sea. Hundreds of fish were dissected in order to ascertain what they fed upon; but only on very rare occasions could any traces of food be found in their stomachs. What, then, do the salmon live upon? was asked. It is quite clear that salmon obtain in the sea some kind of food for which they have a peculiar liking, and upon which they rapidly grow fat; and it is very well known that after they return to the fresh water they begin to lose their flesh and fall off in condition. The rapid growth of the fish seems to imply that its digestion must be rapid, and may perhaps account for there never being food in its stomach when found; although I am bound to mention that one gentleman who writes on this subject accounts for the emptiness of the stomach by asserting that the salmon vomits at the moment of being taken. The codfish again is frequently found with its stomach crowded; in fact, I have seen the stomach of a large cod which formed quite a small museum, having a large variety of articles “on board,” as the fisherman said who caught it. Salmon seldom now attain a weight of more than from fifteen to eighteen pounds. Long ago sixty-pound fish were by no means rare, and twelve years back salmon weighing thirty and forty pounds used frequently to be seen on our fishmongers’ counters. In the golden age of the fisheries salmon are said to have been very plentiful, and attainable for food by all classes of the community, the price being a mere trifle; but railways now carry away our sea produce with such rapidity to far-off cities and populous towns, where there is an increasing demand that the price has risen to such a point as to make this fish a luxury for the rich, and so induce the capture of salmon of all weights. On all these points there has been a great amount of disputation, chiefly carried on in the Transactions of learned societies, and not therefore accessible to the general reader.

It is supposed by some writers that the salmon makes two voyages in each year to the sea, and this is quite possible, as we may judge from the data already given on this point; but sometimes the salmon, although it can swim with great rapidity, takes many weeks to accomplish its journey because of the state of the river. If there is not sufficient water to flood the course, the fish have to remain in the various pools they may reach till the state of the water admits of their proceeding on their journey either to or from the sea. The salmon, like all other fish, is faithful to its old haunts; and it is known, in cases where more than one salmon-stream falls into the same firth, that the fish of one stream will not enter another, and where the stream has various tributaries suitable for breeding purposes, the fish breeding in a particular tributary invariably return to it.

But, in reference to the idea of a double visit to the salt water, may we not ask—particularly as we have the dates of the marked fish for our guidance—what a salmon that is known to be only five weeks away on its sea visit does with itself the rest of the year? A salmon, for instance, spawning about “the den of Airlie,” on the Isla, some way beyond Perth, has not to make a very long journey before it reaches the salt water, and travelling at a rapid rate would soon accomplish it; but supposing the fish took forty days for its passage there and back, and allowing a period of six weeks for spawning and rest, there are still many months of its annual life unaccounted for. It cannot, according to the ideas of some writers, remain in the river forty-seven weeks, because it would become so low in condition from the want of a proper supply of nourishing food that it would die. It is this fact that has led to the supposition of a double journey to the sea. The Rev. Dugald Williamson, who wrote a pamphlet on this subject, entertains no doubt about the double journey. “Salmon migrate twice in the course of the year, and the instinct which drives them from the sea in summer impels them to the sea in spring. Let the vernal direction of the propensity be opposed, let a salmon be seized as it descends and confined in a fresh-water pond or lake, and what is its fate? Before preparing to quit the river it had suffered severely in strength, bulk, and general health, and, imprisoned in an atmosphere which had become unwholesome, it soon begins to languish, and in the course of the season expires: the experiment has been tried, and the result is well known. This being an ascertained and unquestionable fact, is it a violent or unfair inference that a similar result obtains in the case of those salmon that are forced back, from whatever cause, to the sea, that the salt-water element is as fatal to the pregnant fish of autumn as the fresh-water element is to the spent fish in spring?... If there is any truth in these conjectures, they suggest the most powerful reasons for resisting or removing obstructions in the estuary of a river.” The riddle of this double migration of the salmon is likely still to puzzle us. It is said that the impelling force of the migratory instinct is, that the fish is preyed upon in the salt water by a species of crustaceous insect, which forces it to seek the fresh waters of its native river; again, that while the fresh water destroys these sea-lice a new kind infests it in the river, thus necessitating a return to the sea. My own experience leads me to believe that salmon can exist perfectly well in the fresh water for months at a time, suffering but little deterioration in weight, but never, so far as I could ascertain, growing while in the fresh streams, although it is certain they feed. It is a well-known fact that the parr cannot live in salt water. I have both tried the experiment myself and seen it tried by others; the parr invariably die when placed in contact with the sea-water.