And where it does, nutrients upwelling from the depths create lush planktonic feeding zones for the world's fisheries.

n a summer day, when a stiff northerly wind blows along the Oregon coast, and there's a line

in the sea where the color changes from a clear cobalt blue to a murky green— that's a day fishermen know they can make a good catch. And catch they do. The silver salmon, tuna, and other fish congregate in certain greenish areas where they feed on thriving pastures of marine plants and animals—and if the

fishermen are there on the spot, the haul is good.

Fishermen worth their salt in all oceans have long known signals of wind, sea color, frontal lines, and temperatures in their special fishing areas—it's part of the lore of the sea. Yet, although they can recognize areas where the fish might be, they have been unable to predict these spots when winds and sea currents change.

Now, after several years of research, some of the factors that create good catches are becoming beautifully clear.

In many slow and ponderous ways— by action of the t ide^ the rotation of the Earth: and changes in seasons, winds, and temperatures—the waters of the world are constantly mixing, over-iurr.ir.e. and wciim^ up, biir.ging dis­solved chem^ai nutrient- irorn the sea

depths to the surface, and churning oxygen-rich water from the surface down again to the deep sea.

These complex vertical and horizontal motions, vital to the living resources of the sea, may occur in the middle of the oceans, or at boundaries of different water masses, in eddies around the lees of island or land promontories projecting into a current, or over ridges and can­yons beneath the open sea.

However, the most dynamic ocean turnover process is coastal upwelling, a phenomenon by which nutrients from the dark depths are periodically brought up in certain areas to the sunlit surface layers where photosynthesis can take place and where they can become avail­able to microscopic plant life. These one-celled plants, phytoplankton, pro­vide the base of the complex food chain of ocean life. Provided with nutrients and using energy from the Sun for pho­tosynthesis, they multiply into large masses, offering feasting grounds for zooplankton and larger fish and creating the most productive fish-producing re­gions in the world.

Fishing yields in these upwelling areas and their immediate vicinity are at least a thousand times higher than in other oceanic areas. The coastal upwelling areas, comprising only one-tenth of one percent of the total area of the world's oceans, are estimated to contain more than half of the ocean's fish catch—a total fishery yield of more than 40 mil­lion metric tons a year.

Progress in understanding the theory of the upwelling phenomenon has reached a point of worldwide signifi­cance, states Richard Barber of Duke University's Marine Laboratory at Beau­fort, North Carolina, and national coor­dinator of the Coastal Upwelling Eco­system Analysis (CUEA) program. CUEA, part of the International Decade of Ocean Exploration, was started by the National Science Foundation to in­vestigate the physical and biological as­pects of upwelling. With more than 29 principal investigators and 13 U.S. re­search and educational institutions and organizations, CUEA has initiated a series of experiments and theoretical observations. Its purpose is to provide systems models for predicting on a daily basis the changing sites, courses, extent, temperatures, and various other factors of upwelling systems in particular loca­tions. Eventually such system modeling

would be used to predict the production of the world fisheries on the basis of a few significant meteorological and ocean-ographic measurements.

Where it happens

- lthough upwelling may take place anywhere in the ocean, it occurs more regularly and most con­

spicuously along the western edges of continents in the. low and mid latitudes, particularly along the western coasts of the Americas and of Africa. In these regions, the prevailing winds blow equatorward, and this, in combination with the Earth's rotation, causes the surface water to move away from the coast. The surface water is replaced by water from the depths.

There are only a few places in the world where conditions exist to form strong persistent upwelling over large regions. One is along the Peruvian coast, where the Peru Current flows northward west of Chile and Peru. Another region of marked upwelling occurs along the coasts of Baja California, California, Oregon, and Washington, where the California Current flows south. Here the upwelling peak moves up the coast with the warming weather in May, June, and July as the North Pacific atmospheric high pressure cell intensifies and north­

erly winds develop along the coast. By October it is finished. A third intensive upwelling area is along Southwestern Africa, with most intense activity in the southern spring months of September and October. A fourth dominant up­welling system occurs farther north— along Northwestern Africa.

Contrary to the "west coast rule," im­portant coastal upwelling also develops in the region of Eastern Africa where, during the annual southwest monsoon, the Somali Current flows from the South­ern Hemisphere up the east coast of Africa and along the Arabian coast into the Arabian Sea.

Upwelling also occurs in mid-ocean spots around the Equator and in the Antarctic. In the eastern equatorial re­gion of the Pacific Ocean, for instance, the Cromwell Undercurrent creates an uprising in an area extending eastward along the Equator from the 180-degree meridian to the Galapagos Islands.

When the polar wind blows

: " he primary driving mechanism of

t a "typical" coastal upwelling sys­tem is the wind system blowing

from an atmospheric high pressure to­ward the Equator and producing stress at the surface of the sea. Because of the effect of the Earth's rotation and fric-

26 MOSAIC Winter 1974

tonal forces, however, the net transport f the windblown surface water, called ,kman Transport or Drift, is directed eaward, 90° to the right of the wind in he Northern Hemisphere (to the left in he Southern).

As the surface water is pushed off-hore, cold water rises from several hun-ired meters deep, up and over the con-inental shelf, to take its place. This ipwelling may appear at the surface in 'arious patterns of tongues, plumes, and latches. Such tongues or plumes indi-ate intense upwelling locally and may .ssume many changing shapes, ranging n length and depth from a few meters o several kilometers. However, they eldom exceed ten to 30 kilometers in vidth, and ten to 20 meters in track­less. The tip of the tongue of intense ipwelling usually can be found within en to 20 kilometers off the coast. :rontal boundaries between the warm old surface water) and cold (more lewly upwelled) water masses are often iharp and distinct. Some occur over long listances, others over a space so small hat a single ship may straddle the >oundary.

An inherent feature of upwelling seems to be the presence of a narrow etlike surface current that flows along he shore in the same direction as the prevailing winds on the seaward side of :he upwelling front. At the same time is the surface current is flowing, a sub­surface countercurrent is often observed -lowing away from the Equator. This is :onsidered a very important factor in :he dynamics of upwelling and its asso-:iated ecosystem. Just how much these :urrents contribute to upwelling under /arious conditions and what effect they produce is not yet clear, points out phys-cal oceanographer Robert Smith of Ore­gon State University, which was the renter of extensive upwelling experi-nents during the summers of 1972 and 1973.

Each regional upwelling ecosystem is a separate, complex, and dynamic phe­nomenon that depends upon the physical conditions of its setting. Each is subject not only to variations within the system itself—such as the configuration of the :oast and continental shelf, the strength and directions of ocean currents, and the local wind conditions—but also to influ­ences external to it, such as the seasons and the world wind patterns.

What makes it happen. Strong winds blowing along the shore toward the Equator, combined with the Earth's rotation and frictional forces, drive the warm surface water away from the shore. It is replaced by cold, nutrient-rich water from the lower depths; phytoplankton flourish, and fish congregate to feed on the plankton.

Unpredictable prodigy

-,' lthough the upwelling regions seem well defined, the process itself

" has, as yet, no constant or de­pendable schedule of when it might arrive or how long it will last. The length of time an upwelling season may prevail depends primarily upon how long the dominating winds blow along the coast. This in turn depends on the strength and positions of the atmos­pheric highs that occur as spring and summer arrive. During the season when conditions are generally right for up­welling, the process may vary from strong persistent upwelling to none at all to strong again over a period of weeks.

These modulations may occur several times during a season of upwelling con­ditions. They occur when the prevailing

winds stop blowing in the direction favorable to upwelling—equatorward along west coasts—and come from other directions, hence stopping the offshore transportation of the warm surface wa­ter. This in turn shuts off the upwelling circulation of water from lower depths. The cold water remains below and the warm water above in horizontal layers. These wind changes of a few days' dura­tion have large effects on water tempera­ture over areas as wide as ten kilometers from the shore and as deep as 20 meters.

Once the source of nutrients is stopped or blocked, the growth of phytoplankton halts, as does the concentration of fish. The whole process collapses and the fish disperse to find their own food where they can, and fishing for the day, the week, perhaps longer, can become a haphazard affair for the fishermen.

MOSAIC Winter 1974 27

W i t h the re turn of the prevai l ing

nor ther ly winds (or southerlies in the

Southern Hemisphere) , upwell ing re­

sumes , and p lank ton growth and con­

centrat ion of mar ine life reoccurs.

Some upwell ing systems take place

year after year in specific areas. O the r s

m a y cont inue for several years wi thout

in ter rupt ion and then fail ca tas t rophic-

al ly—such as the failures of upwell ing in

1965, 1971 , and 1972 off the coast of

Peru. In previous years, the Peruvian

upwell ing has created the world 's most

product ive fishery area. In 1970, 22 per­

cent of the total world fish ca tch—most ly

anchovies—was harvested. W i t h the ab­

sence of upwell ing—el Nino or " T h e

Chi ld ," as it is called—in 1971-72, the

anchovy catch dropped from 12.3 million

tons in 1970 to 4.5 million tons in 1972

— a t ragedy for Peru which for decades

had depended on the more t han ten mil­

lion tons of anchovy catch, from which

near ly 70 percent of the world 's fishmeal

was produced. Scientists say the fish

stocks are slowly recovering wi th the

resumpt ion of upwel l ing in 1973, bu t

they have not yet mult iplied to their

former numbers . This d is rupt ion has

raised several quest ions as to whe the r

the diminished number s of anchovies are

caused by overfishing dur ing el Nino, or

perhaps by a na tura l decrease in the

biological cycle of the fish. O t h e r tragic1

failures blamed on similar circumstances

were the disappearance of the California1

sardine and Hokka ido herr ing .

The sunlit zone

i thout doubt , coastal upwell ing

systems produce rich biological

g rowth and activity. This high

productivi ty of organic mat te r is limited

to the sea surface layers where sunlight

is sufficient for pho tosyn thes i s . Solar

radiat ion penetra tes t h r o u g h this upper

sea layer, the euphotic zone, to depths

of about 11 to 28 meters , depending on

the concentrat ion of the mar ine popula­

tions or on turbidity. Into this zone are

b rought up the deep sea's n i t rogen, phos­

phorus , and silicon; in ion form or as

compounds of ni t ra tes , ni t r i tes , phos­

phates , and silicates. I ron and traces of

other minerals are also present .

At first, the cold, newly upwelled wa­

ter is low in plant and animal popula­

t ion; it takes a while for p r imary bio­

logical activity to start , explains Richard

Dugdale , a biological oceanographer

from the Universi ty of W a s h i n g t o n . As

one-celled p lankton mult iply , they grad­

ually consume and reduce the amoun t of

nut r ients . At the same t ime, oxygen con- '

tent increases. Along the surface waters ,

oxygen is near sa tura t ion , and toward

the seaward edge of the spreading plume'

it has been measured as h igh as 130 per­

cent of saturat ion.

As an indication of the extent to which

upwell ing increases product ion of pri­

mary marine life, p h y t o p l a n k t o n cell

counts in the Peruvian upwel l ing eco­

system, in a good year, have been meas­

ured as high as 138,000 per liter. This

compares to a normal ocean densi ty of

1,000 to 10,000 per liter.

Feeding directly on the p lant and ani­

mal p lank ton are the herb ivorous zoo-

p lank ton and fin fishes, such as tuna ,

salmon, anchovies, mullet , and herr ing,

which are caught by f ishermen or eaten

by other carnivorous preda tors including

birds , boni to , squid, and sea lions. In

the Peruvian region, it is est imated that

the annual numbers of fish captured by

fishermen are probably matched by those

consumed by mar ine p reda tors .

As the upwell ing tongue of cold water

spreads over the sea surface and is

28 MOSAIC Winter 1974

oved seaward by the wind, it carries e products of this biological activity—• e excreta, dead and decaying plants, limals, and other organic compounds—-hich gradually sink toward the bottom • the sea. As this material drifts down-ard, it is acted upon by bacteria near e surface which reduce it again to in-•ganic nutrients that may be taken up / phytoplankton, dissolved into the sea, • come to brief rest on the sea floor ;fore being upwelled again—a complete :osystem recycling. Moreover, though the processes are

3t yet well understood, there seems to i nutrient recycling within various lay­'s arid currents of the sea in an up-elling region—through local mixing and mvection currents, or subsurface shore-ard transport, or through injection at ie source of upwelling. The proportion : regenerated nutrients in a fully devel-?ed upwelling ecosystem is quite high, 'ne estimate is that a dense school of srbivorous fishes grazing on a phyto-.ankton crop, through its excreta alone, roduces the daily nitrogen requirements " the phytoplankton in just two hours.

xpeditions for upwelling

cientists have been aware of up­welling for a long time, particu­larly along the coast of Peru,

'here the occurrence of el Nino has been ?corded by fishermen for more than 30 years. Scientific attempts to define nd describe the upwelling system itself, owever, did not occur until the early 900's. In the late 1920's and 1930's, idividual oceanographers began making tajor contributions to the studies. In 968 an Upwelling Biome Program was icluded as ; part of the International iological Program, and studies were lade along the Peruvian coast and in the lediterranean. With CUEA established i 1971, four expeditions took place in ie succeeding two years to investigate ie biological and physical effects of pwelling: MESCAL I and II off Baja alifornia in the springs and summers f 1972 and 1973; and CUE I and II off \e Oregon coast in the same years.

The latest major experiment, CUE II, perating from July through August 973, took place on a site some 80 kilo-leters long along the Oregon coast 'om Newport to Cape Lookout, and ^tending some 60 kilometers into the acific Ocean. CUE II, co-directed by

James O'Brien of Florida State Univer­sity and Dale Pillsbury of Oregon State University, was set slightly north of the 1972 CUE I site, at a place where the topography of the continental shelf is simpler and smoother. Here scientists hoped to avoid the complicated sea cir­culations created by ridges and bumps of the sea bottom and to simplify the simulations of models.

Three research vessels—the "work­horse" Cayuse which can make a 180° turn "on a quarter" to place or pick up buoys and objects from the sea; and the more elegantly equipped Oceano-grapher and Yaquina—made repeated journeys back and forth over the area to measure temperatures, salinities, den­sities, and changes in currents. On an­other vessel, the Thomas G, Thompson, scientists made detailed studies on chem­ical nutrients, plankton, and fish, and compiled maps charting temperature zones, flow of currents, and areas of nutrients and biological activity. An in­strumented aircraft from the National

Center for Atmospheric Research oper­ated over the area during August, meas­uring sea surface temperatures, air hu­midity and temperatures, and wind systems.

Since 1965, arrays of buoys moored on Oregon's continental shelf have been used to record currents and tempera­tures. During CUE II more buoys were installed in arrays extending from land out to sea some 60 or more kilometers— across the continental shelf and over the edge of the continental slope. These buoys—spaced several kilometers apart, depending on the configuration of the sea floor or the currents—recorded tem­peratures and currents from the surface to the sea floor. They helped scientists "follow" various ebbs and flows of cur­rents as the winds changed and the sea­son progressed. Buoys from NOAA's Pacific Marine Environmental Laboratory were moored at single points along the array to measure the wind, solar radia­tion, and currents near the surface. Buoys from Oregon State University

MOSAIC Winter 1974 29

Taking the sea's temperature, Equipment is placed at strategic points off the Oregon coast during CUE-ll.

measured current velocities and direc­

tions at different depths.

Scientists found the 1972 data lacking

in adequate information on wind direc­

tions and changes. Since wind is rec­

ognized as the major driving force in

upwelling systems, emphasis was made

in 1973 on increasing wind data from

anemometers on land and sea stations.

In addition to new data-gathering

techniques and equipment, a wholly new

shipborne computerized data storage,

processing, and display system was used

in 1973, packed totally in a van about

half a room large, and placed on board

the Thomas G. Thompson. This system

acquired data on the spot, processed it, and provided scientists with a nearly

"real time" look at the area they were

studying to help them update their plans during the cruise.

A step closer to prediction

ome parts of the upwell ing process

have been successfully simulated

on two-dimensional , two-layer ,

t ime-dependent numerical models over

coastal regions of simple topography

under steady wind condit ions. James

O'Brien and John J. Walsh , Univers i ty

of Wash ing ton , are working on models

tha t encompass basic features—the slope

and configuration of the coastal shelf,

the direction and speed of wind, b io­

logical variables, the flow of currents

and countercurrents , and the size and

movemen t of the upwell ing.

But since upwell ing is a th ree-d imen­

sional affair, actually four w h e n one con­

siders the time factor, O'Brien and his

co-workers are developing a three-

dimensional , t ime-variable circulation

model to handle the m a n y variables oc­

curr ing during upwell ing. " W i t h this

mode l , " O'Brien says, " w e hope to pre ­

dict factors such as wid th of the upwel l ­

ing tongue , the times and areas for

upwel l ing to appear, and the flow of

currents .

"Numer ica l models of t ime-dependent

oceanographic phenomena have a par­

ticularly promising fu ture ," he says.

" W i t h models from exper iments CUE I

and II already feeding forecasts on a

general scale, we hope numerical studies

will be applied to other upwel l ing re­

gions th roughout the wor ld . "

The accumulation of data and test ing

of ha rdware and techniques du r ing CUE

II and other CUEA exper iments have

been building up to a large in terna t ional

project, J O I N T I, scheduled for February

t h rough M a y 1974 off the no r thwes t e rn

coast of Africa.

" J O I N T I is the first major exper iment

wi th all components of the CUEA pro­

gram functioning toge ther , " says Barber.

The internat ional research project will be

conducted in the area of Cape Blanc in

cooperat ion with scientists from France,

G e r m a n y (East and W e s t ) , U.S.S.R.,

Tracks of winds, Arrows on this vector chart show how the wind blew daily aiory, the Oregon coast during July and Auguj-i "f 1972. Prevailing winds blew from the nc.!-> most of the time, but reversed around July 2, 6, 31, and August 15. During theo< reversals, upwelling slowed, shore watei temperatures rose, and fishing was generally poor until north winds picked up again.

Spain, the United Kingdom, and Mauri­tania—all participants in an even larger international program called Cooperative

Investigations of the Northern Part of

the Eastern Central Atlantic.

"The primary research objective of

JOINT I is exactly the same as the cen-

30 MOSAIC Winter 1974

al scientific objective of the CUEA pro-•am," he says: "to develop a total sys-m model of the complex process of swelling." The complete understanding of the

swelling phenomenon depends on the entification and correlation of changes . global atmospheric and ocean current rculations and in local mesoscale ep­ilations—essentially on the dynamics lat drive, or fail to drive, upwelling. More data on physical processes and

lechanisms are still needed. For in-:ance, what are the effects on upwelling 'om irregularities of the sea bottom )pography? What energy transfers oc-xv from the wind to the ocean surface i different wind velocities and under iffering conditions of surface sea rough-ess? What are the qualitative appor-onments of sources of upwelled water nder different conditions of tempera-ires and currents? These are some of \e questions that scientists plan to ex-lore during the JOINT I expedition.

rotecting the ocean's resources

he major practical benefit of an up­welling prediction system for loca­tions throughout the world is that

shermen will be able to obtain an bove-average harvest with less time 'asted searching for fishing locations. . potential hazard, of course, is that nee the actual time and place of up-'elling can be predicted, fishermen will verfish the resources of the sea.

"Scientists are aware of the possibil-ies that, with scientific and technolog-:al knowledge such as we are finding, shermen may take more from the sea aan can be naturally replaced," says arber. Any kind of control over fishing ghts and international legal codes is Dmplex and hard to enforce, especially >r the smaller coastal nations. Cer-linly, lack of regulation has contributed } the ruin of several fishing industries—-le California sardines, for instance, or ae menhaden on the East Coast.

Overfishing as well as other factors ach as ocean pollution is a serious threat ) be considered and controlled in order D maintain life and productivity of the ea. "Yet we have to be careful in inter-reting what we think affects the marine opulation," points out Barber. "Other actors have to be considered—for in-tance, the natural biological cycles of

International rendezvous. In the summer of 1974 scientists from more than half a dozen nations will fake part in JOINT I to study upwelling dynamics off the West African coast.

fish population. At times a species of fish may become abundant; at other times in their biological cycle there may be a natural decrease in their numbers."

By gaining a deeper understanding of the physical and biological dynamics of upwelling, scientists, fishermen, and na­tional legislators will have more poten­tial control over the supply of fish stock. "In other words," Barber says, "scien­tists can forecast the possibility of up­welling and hence productivity of fish in certain local areas. The fishing indus­try and national resources offices can then be alerted as to whether they should reduce their fishing quota or shorten the fishing season to let the fish

stock be replenished. Or in a good year they can increase their fishing harvest without damaging the stock."

Already, In some countries, fishing controls have been Instituted. In Peru, for instance, fishing regulations are ex­tremely strict. For the small, newly de­veloping coastal countries it is important that their marine resources be under legal protection.

"For the world as a whole," says Bar­ber, "there is a high payoff in the new scientific and technological knowledge of upwelling and fish harvest. Large and small nations need cooperation in order to preserve, protect, and manage these resources of the sea." •

MOSAIC Winter 1974 31