Saturday 27 June 2009

Science Studies the Sardine (Ed Ricketts 1947)

The following is the full text of an article published by Ed Ricketts in the Monterey Peninsula Herald in 1947.

Unfortunately for the sardine, and the extended marine food chain that it forms part of, Ricketts was killed in May 1948 and his deep ecological insight and campaigning capability never helped save the sardine. Much later, in 1998, well known fisheries ecologist Dr Daniel Pauly published a seminal paper in Science called 'Fishing Down Marine Food Webs'. This is both a citation classic (with over 1,000 citations) and a highly influential paper. Pauly was not aware of Ricketts work when his paper was published.

Science Studies the Sardine

Mysterious Disappearance Focuses Attention on Woeful Lack of Information Regarding Billion Dollar Fish

By EDWARD F. RICKETTS, Pacific Biological Laboratories

The Herald has undoubtedly reported waterfront opinion correctly in stating that the shortage of sardines is being attributed to a change in the currents. I doubt very much if we can rely on such a simple explanation. I am reminded instead of an old nursery rhyme. Like the "farmer-in-the-Dell" there's a long chain of events involved. And you have to be familiar with all of them in order to know any one very clearly.

This is complicated still further by the fact that scientists haven't yet unravelled it all completely. But already quite a lot of information is available, and from most of the parts we can piece together some sort of picture puzzle. The result may be a labyrinth, but there's no way to avoid it. We just have to be patient and try to follow it through. Because I've done this myself after a fashion, perhaps I can be better than no guide at all.

By means of a very efficient straining apparatus in the gills, sardines are able to feed directly on the most primitive foodstuffs in the ocean. This so-called "plankton," chiefly diatoms (free floating microscopic plants) is the product of oceanic pastures, and like grain and grass and root crops, bears a direct relation to sunlight and fertilizer. Except that in the oceans of course you don't have to depend on the rains for moisture.

Some of these ocean pastures produce more per acre than the others. This is due to variations in the amount of fertilizer brought to the surface by a process called "upwelling."

Only the upper layers of water receive enough light to permit the development of plants. In most places, when the sunlight starts to increase in spring, these plants grow so rapidly that they deplete the fertilizer and die out as a result. In the familiar pattern of dust to dust and ashes to ashes, their bodies disintegrate and relase the chemical elements. These, in the form of a rain of particles, contantly enrich the dark-deeper layers.

On the California coast - one of the few places in the world, incidentally, where this happens - winds from the land blow the surface waters of the shore far out to sea. To replace these waters, vertical currents are formed which bring up cool, fertilizer laden waters from the depths to enrich the surface layers, maintaining a high standard of fertility during the critical summer months. Since the seeds of the minute plants are everywhere ready and waiting to take advantage of favorable conditions, these waters are always blooming. It's a biological rule that where there's food, there's likely to be animals to make use off it. Foremost among such animals is the lowly sardine.

In the long chain, this is the first link. Reproductive peculiarities of the sardine itself provide the second. Above their immediate needs, adult sardines store up food in the form of fat. During the breeding season, ALL this fat is converted into eggs and sperm. The adult sardine is nothing but a factory for sexual products.

The production of plankton is known to vary enormously from year to year. If feeding conditions are good, the sardines will all be fat, and each will produce great quantities of eggs. If the usual small percentage of eggs survive the normal hazards of their enemies, a very large year class will be hatched.

If then feeding conditions are still good at the time and place of hatching (spring in southern California and Northern Mexico), huge quantities of young sardines will be strewn along the Mexican coast by south-flowing currents. Here their enemies are also abundant. Including man - chiefly in the form of bait fishermen from the tuna clippers. Those surviving this hazard move back into California waters, extending each year further and furher up the coast, the oldest finally migrating each summer clear up to Vancouver Island. All return during the winter to the breeding ground. This process builds up until a balance is established. Or until man, concluding that the supply is in fact endless, builds too many reduction plants on that assumption.

On the other had, the small year classes resulting from decreased plankton production, will in themselves deplete the total sardine population. If then the enemies-again chiefly man - try desperately to take the usual amounts, by means for instance of more and larger boats, greater cruising radius, increased fishing skills, etc, sardine resources can be reduced to the danger point.

All this being true, we might be able to forecast the year classes if we could get to know something about the conditions to which the adults are subjected at a given time. Their eggs are produced only from stored fat. The fat comes only from plankton. And there are ways of estimating the amount of plankton produced.

An investigator at the Scripps Institution of Oceanography long ago realized the fundmental importance of plankton. He has been counting the number of cells in daily water samples for more than 20 years. This scientist, now retiring perhaps discouraged because the university recently hasn't seen fit even to publish his not-very-spectacular figures, ought to be better known and more honored. He deals with the information of prime importance to the fisheries. But in order to get this information in sufficient detail, you have to know the man, and get him to write you about it personally.

Figures from only a single point have very limited value. We should have data of this sort for a number of places up and down the coast so as to equalize the variations; and for many years. But we're lucky to have them even for La Jolla. The graph shows 1926, 1931, 1934 to have been poor years, but during those times the total sardine landings were still apparently well within the margin of safety. Years 1941-42 were also poor. But during this time the fishery was bringing in really large quantities. The evidence is that very lean adults resulted from these lean years, producing few eggs. And we would have done well take only a few of them and their progeny. A glance at the chart labelled "California Sardine Landings" will show what actually happened instead.

There's still another index of sardine production. This time the cat of the wife of the farmer-in-the-dell catches herself a fine succulent mouse.

We know that the food of the sardine depends directly on fertility. And that fertility depends on upwelling. Obviously, the water recently brought up from depths is colder than at the surface. When upwelling is active, surface temperatures will be low. Now we can very easily calculate the mean annual sea water temperatures from the readings taken daily at Hopkins Marine Station and elsewhere. The chart which has been prepared to show these figures bears out again the fact that 1941 and'42 must have been unfortunate years for the sardines. Following those years we should have taken fewer so as not to deplete the breeding stock.

Instead, each year the number of canneries increased. Each year we expended more fishing energy pursuing fewer fish. Until in the 1944-46 seasons we reached the peak of effort, but with fewer and fewer results. Each year we've been digging a little further into the breeding stock.

A study of the tonnage chart will show all this, and more. The total figures, including Canada, tell us pretty plainly that the initial damage was done in 1936-37, when the offshore reduction plants were being operated beyond regulation. And the subsequent needs of the war years made it difficult then also for us to heed the warnings of the scientists of the Fish and Game Division.

The answer to the question "Where are the sardines?, becomes quite obvious in this light. They're in the cans! The parents of the sardines we need so badly now were being ground up then into fish meal, were extracted for oil, were being canned; too many of them, far too many.

But the same line of reasoning shows that even the present small breeding stock, given a decent break, will stage a slow comeback. This year's figures from San Pedro, however, indicate no such decent break.

During this time of low population pressure, the migrating few started late, went not far, and came back earlier than usual. Actually we had our winter run during August and September when the fishermen were striking for higher rates. By the time we had put our local house back in order, the fish had gone on south. Many had failed to migrate in the first place, and were milling around their birthplace in the crowded Southern California waters. And the San Pedro fleet, augmented by out-of-work boats from the northern ports, has been making further serious inroads into the already depleted breeding stock.

My own personal belief is nevertheless optimistic. Next fall I expect to see the fish arrive, early again, and in somewhat greater quantity. But a really good year will be an evil thing for the industry. And still worse for Monterey. Because we'll forget our fears of the moment, queer misguided mortals that we are! We'll disregard conservation proposals as we have in the past; we'll sabotage those already enacted. And the next time this happens we'll be really sunk. Monterey will have lost its chief industry. And this time for good!

If on the other hand, next year is moderately bad - not as bad as this year, Heaven forbid, but let's hope it's decently bad! - maybe we'll go along with such conservation measures as will have been suggested by a Fish and Game Commission which in the past has shown itself far, far too deferent to the wishes of the operators - or maybe to their lobby!

We have before us our own depleting forests. We have Sweden's example; now producing more forest products every year than it did a hundred years back when the promise of depletion forced the adoption of conservation measures. We have this year's report on our own halibut landings, like the old days - the result solely of conservation instituted by a United States-Canadian commission which took over in the face of obvious depletion.

If we be hoggish, if we fail to cooperate in working this thing out, Monterey COULD go the way of Nootka, Fort Ross, Notley's Landing, or communities in the Mother Lode, ghost towns that faded when the sea otter or lumber or the gold mining failed. If we'll harvest each year only that year's fair proportion (and it'll take probably an international commission to implement such a plan!) there's no reason why we shouldn't go on indefinitely profiting by this effortless production of sea and sun and fertilizer. The farmer in the dell can go on with his harvesting.

This text from material reprinted for educational purposes by Roy van de Hoek, in its entirety from the newspaper:
MONTEREY PENINSULA HERALD 12th Annual Sardine Edition, p.1,3 March 7, 1947.