Monitoring the Ocean Environment - NMFS Scientific...
Transcript of Monitoring the Ocean Environment - NMFS Scientific...
MFR PAPER 1174
Monitoring the Ocean Environment
L. E. EBER
INTRODUCTION
Atmospheric and oceanographicconditions in the vicinity of the sea surface have historically been monitoredby mariners and fishermen. From theirobservations has come much of ourknowledge of the marine climate. Suchobservations, taken four times daily,recorded in weather logs and transmitted by radio to shore stations stillconstitute the primary source of information on surface conditions over theworld ocean. This information is nowsupplemented by data from weathersatellites which provide a major advance in global monitoring. The ~alue ofsatellites for surveillance of atmospheric and oceanic conditions will increase greatly as sensor technology andprocessing techniques evolve.
There exists no systematic monitoring of subsurface conditions that can beconsidered comparable to surfacemonitoring. Subsurface temperaturesare taken with XBT (expendablebathythermograph) systems installedon U.S. Navy vessels and on selectedmerchant ships which travel regularroutes. Time-series data are providedby ocean station vessels (which arebeing withdrawn from service), and afew moored buoys and by sea-level stations at coastal and island locations.Sea-level data can give an indication ofmean density in the water column in thevicinity of the station. Research vesselst~ke subsurface observations of manykmds, but at times and places pursuantto particular objectives. Such reportsmust be considered as incidental toroutine monitoring systems.
The basic purposes of monitoring themarine environment are to collectsynoptic observations adequate for investigation of significant fluctuations inmomentum and heat exchange and theireffects on atmospheric and oceanic circulation, and on the distribution of relevant properties. Advances in the basicunderstanding of the ocean-atmospheresystem have application to all activitiesaffected by it, including transportation,military operations, harvesting andmanagement of natural resources, recreation, etc. Particular applicationsmay pose differing requirements uponthe monitoring system with respect totime and space scales and to the properties monitored, although there are areasof overlap.
For many of these applications theexisting monitoring system is considered inadequate. I The obvious shortcomings are the lack of surface observations outside normal shipping lanes andthe general deficiency of subsurface observations, except along a few chosentracks. Less obvious perhaps are thedifficulties in making direct measurements of many important parameters and the uncertainties inherent incomputing heat and momentum fluxfrom existing observations. Not onlyare the semi-empirical formulas commonly used to compute these fluxes subject to question, but the actual parameter values used in the formulas (cloud
'The status of .oceanographic monitoring effortsa~d a .speclficatlon of needs for expansion are de·taJle~ m a recent r~po~! entitled "The ocean's rolem climate prediction, available from the OceanAffairs Board of the National Academy of Sci·ences, Washmgton, D.C.
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amount; wind speed; and sea, air anddew point temperature) are subject toobservational error. Nevertheless, inthe sociopolitical, economic, and technological framework of today, there isno meaningful alternative to the existingdata collection system from ships of opportunity (i.e., vessels whose primarymission is not collection of data) forlarge-scale moni toring of environmentalconditions.
There are, however, many ways inwhich this system can be modified andsupplemented to improve both the distribution and quality of environmentalobservations. Such augmentation ofenvironmental monitoring will tend tobe selective insofar as large-scalemonitoring is supported mostly by government agencies, and the determination of where. when, and what to~onitor is guided by an agency's objectives or mission.
The U.S. Navy, whose ships andshore stations contribute to the basicsyst~m,. also supports supplementarymomtorIng from ships of opportunityto meet its needs for surface and subsurface data from areas not well cov~red by the basic system. It operatesm both a direct mode, maintaining itsown liaison with cooperating ships,a.nd als.o indirectly through cooperatIOn With marine-oriented academicinstitutions and with other governmentagencies, including the NationalOceanic and Atmospheric Administration's (NOAA) National Marine Fisheries Service (NMFS).
Academic institutions undertake thesolution of a broad range of problemsformulated to advance understanding ofth.e ocean .and atmosphere. They contnbute directly to environmentalmonitoring through the activities of research vessels. They also contribute tothe planning and improving of monitoring systems through investigation ofspace and time scales relevant tosignificant processes and events, development of instrumentation andmethods of measurement suitable forlarg.e-s~ale monitoring, and through 01'
gamzatlon of observational programsneeded to fill gaps in existing systems.
Weather satellites provide full globalcoverage of weather systems, over
L.. E. ~ber is with the SouthwestFI.shen.es Center, National MarineF/shenes Service, NOAA La JollaCA 92038. "
Figure 1.-Envlronmental data received over National Weether Service teletype circuits are recorded onpaper tape,transferred to punched cards, and Inspected for quality control. The cards are then used to updateenvironmental data tiles on disk for computer processing.
periods of about 12 hours, and partialcoverage of surface conditions depending on cloud distribution. The NationalEnvironmental Satellite Service ofNOAA. which operates this system, isprimarily concerned with the sensing,reduction, and presentation of data, andhas put much effort into analysis andinterpretation of satellite data to facilitate user application.
In general, then, agencies and institutions draw selectively from the conglomerate environmental monitoringsystem according to their requirementsand contribute to the total system byimplementing subsystems, either on aunilateral or cooperative basis, to bol-
ster weaknesses in particular missionrelated areas. The primary purpose ofthis review is to describe some of theactivities at the Southwest FisheriesCenter (SWFC) which fall within thatcontext. First, however, we will touchbriefly upon a few of the attributeswhich might be considered desirable inan optimum monitoring system.
THE IDEAL SYSTEM
If sociopolitical, economic, and technological constraints are ignored, wecan envisage the establishment of aWorld Ocean and Atmospheric Agency(WOAA) with effective capability for
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global monitoring. The WOAA couldestablish centers for collection, reduction, and analysis of all environmentaldata. The processed data could beloaded into a real-time data base accessible to user agencies and institutionsthrough a time-sharing network. Thereal-time data base could be updated atintervals pertinent to the events or conditions being monitored. Data displacedfrom the real-time data base would beadded to an historical data base in orderto update time series and long-termmeans.
User agencies could select, manipulate, and further analyze data fromeither the real-time or historical databases and, if appropriate, store resultsback into the system to be available toother users in the network. For example, generalized weather forecasts prepared by a world or nationalmeteorological center might be retrieved. through the time-sharing network, at some particular serviceagency's center and tailored to theneeds of that agency's constituency.
Consider the application of this conceptually ideal monitoring systemtoward achievement of efficient harvesting of living marine resources andeffective resource management. Theenvironment relates to these objectivesin several ways. Thermal conditions,for example, establish the territorialrange which particular species inhabit,and therefore delineate the fishinggrounds. In temperate and colderzones, thermal conditions may havelarge seasonal variations which influence migration patterns and therefore delimit the fishing season. Deviations from normal environmentalconditions affect the survival (abundance) and migration behavior (availability) of fish. Prognostic informationon long-term trends in environmentalconditions and on anomalous year-toyear fluctuations could be applied inplanning and policy decisions by producers, processors, and resource managers. Analyses and short-term prognoses have application for tactical andoperational decisions.
Oceanographic analyses applicableto fishing operations might include surface temperature and salinity, surfacecurrents. location of surface convergence and divergence lines, subsurface thermal and salinity structure, andsubsurface current structure.
Figure 2.-$88 surface temperature data applicationare edited, summarized, and plotted by computer. TheIInal analysis of Isotherms is drawn by hand. Suchmaps appear monthly in the publication FishingInformation.
For planning and management applications which do not require environmental information on a real-time basis,analyses of oceanic properties could beprepared for time spans associated withsignificant changes in a fishery during orbetween seasons. The selection ofproperties or fields to be analyzed couldbe based on either established or potential information value. Particularanalyses with wide application might beloaded into a special products data-basein the time-sharing network and madeavailable to nonagency users,fishery-related or otherwise.
Environmental research to advancebasic understandi ng of processes and todevelop applications could providefeedback into the monitoring systemthrough refinement of the specificationof time and space scales for observational networks, the properties to bemeasured and the observing techniques.
In summary, the principal elementsof the idealized environmental information system are:
I) Capability for global monitoring ofoceanic and atmospheric properties,circulations, and energy and momentum fluxes on time and space scalescommensurate with significantfluctuations and events in the oceanatmosphere system.
2) Global collection and data reduction and archival facilities in which historical and current environmental databases would be maintained and madeaccessible to user agencies and institutions in a time-sharing network.
3) Partitioning of basic analysis andforecast responsibilities among useragencies according to their respectivemissions or objectives. Adaptation ofbasic outputs by other agencies tosatisfy particular constituency requirements.
4) Global radio and satellite communications capability for coordinatedtransmission of environmental information products to ships at sea and remoteland stations.
5) Provision for an environmental information products file in the time-
sharing system for users with requirements for immediate access to theinformation.
6) Provision for timely preparationand dissemination by mail of timeaveraged analysis and other productsnot in immediate demand.
7) Ongoing research to advance understanding of basic processes in theocean-atmosphere system, to developcapability to predict anomalousfluctuations and, for fisheries management, to determine the effects on thefisheries of such fluctuations.
ENVIRONMENTALMONITORING ACTIVITIESAT THE SOUTHWESTFISHERIES CENTER
Three principal activities concernedwith contribution to and application ofenvironmental monitoring which havebeen developed at the SouthwestFisheries Center (SWFC) are: I) the
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radio facsimile (FAX) advisory program, 2) the publication of FishingInformation, and 3) the expendablebathythermograph (XBT) ship-ofopportunity program.
FAX Program
The FAX program evolved out of theneed to supplement the existing environmental monitoring effort in theeastern tropical Pacific. Recognition ofthis need was stimulated by EASTRap AC, an international cooperativeinvestigation of the eastern tropicalPacific, which was intended to produceinformation necessary for a more effective use of the marine resources of thatarea, especially tropical tunas. It wasapparent that biological and physicalproperties alike were subject tosignificant spatial and temporal variations. It was also apparent that the tropical tuna fishing fleet afforded the bestopportunity for obtaining environmental observations in the tuna habitat.
Figure 3.-0bservattons of cloud cover and weather phenomena transmitted from NOAA weather satellitescan be received directly at the Southwest Fisheries Center. Appllcallon 01 satellite data to monitor oceansurface conditions Is under development.
The NMFS's need for data from thl:eastern tropical Pacific was shared bythe U.S. Navy's Fleet NumericalWeather Central (FNWC). Environmental data are used by FNWC to prepare analyses and forecasts of oceanicand atmospheric fields in support ofU.S. Navy operations. Consequently,FNWC requires this data on a real-timebasis.
The NMFS and FNWC recognizedtheir mutual interest in enlisting thecooperation of fishermen for collectionand transmission of observational data.They also recognized both an obstaclein securing such cooperation-thatbeing a disinclination of tuna vessel captains to reveal their position on thefishing grounds-and a need to providethe fishermen with some incentive totake and transmit observations. The obstacle was removed through innovationof an encoding scheme for transmittingdata messages which assured skippersof confidentiality with respect to theirposition. The incentive was provided inthe form of wind, weather, and sea-stateadvisory charts, prepared especially forthe area of the tropical tuna fishery andtransmitted by radio facsimile fromNMFS-licensed radio station WWD.
To implement the program, facsimile
recorders were procured from government surplus and adapted for use withshipboard communications equipment.These recorders have been installed onmore than 55 participating vessels undera reciprocal agreement providing fordaily data transmissions from the fishinggrounds. In addition, there are approximately 20 vessels in the program withprivately owned units. Each vessel isfurnished with its own unique encodingchart prepared at FNWC. The decoding keys are locked into the Navy computer, accessible only to the programwhich processes the observational messages. All participating vessels are expected to take and transmit surfaceweather observations, including windspeed and direction, weather, cloudcover, barometric pressure, air temperature, sea-surface temperature, swelldirection, and wave height. Some 20-25vessels in the tropical tuna fleet areequipped with XBT systems anci reportsubsurface temperatures in theBATHY message format. TheBATHY messages include temperatures and depths at significant pointsdown to 500 meters, extracted fromX BT analog traces. Maintenance of theXBT and FAX equipment is performedby SWFC personnel.
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In practice, tuna vessels at sea begintransmission of weather and BATHYmessages to station WWD each dayabout midafternoon. The messages arerelayed via teletype line to SWFC andaccumulated on a magnetic tape loop inthe collect and transmit terminal unit ofthe Navy Environmental Data Network tie-line. At scheduled times, messages accumulated on the magnetic tapeare sent over the tie-line to the computerat FNWC, decoded and processed forinput to the FNWC operational programs. The decoded messages, alongwith other reports from the eastern tropical Pacific region, are sent back overthe FNWC tie-line to SWFC and also tothe NWS forecast office at RedwoodCity, Calif.
Data originating from tuna vessels,received at SWFC from FNWC, arepunched on cards to be added to theenvironmental data base. Wind andsea-state parameters are extracted fromthese data and plotted on the currentworking charts used in preparation ofthe FAX advisories. Synoptic marinereports from merchant ships receivedover NWS meteorological teletype circuits also are used for this purpose,along with analyses and forecasts received over the NWS facsimile line andthe FNWC tie-line and satellite picturesfrom NWS facsimile and from theSWFC direct readout system.
The weather advisory charts developed by the FAX program at theSWFC consist of a wind and weatherforecast and a sea-state forecast. Priorto August 1974, these charts weretransmitted from station WWD dailyexcept Saturday and Sunday at about4: 15 p.m. The format and l:ontent of theSWFC FAX charts evolved throughfeedback from the fishermen. In addition to forecast wind speeds and directions, they depict the configuration ofthe Inter-Tropical Convergence Zone(ITCZ) and the locations of incipienttropical storms, which tend to developalong it. Such storms can intensify suddenly and pose a hazard to tuna boatswhich tend to fish in or near the ITCZ,trying to avoid strong prevailing windsoutside but also wary of disturbancesinside.
The National Weather Service(NWS) became a participant in the program in June 1974. A data line was established from the NWS forecast office,Redwood City, Calif., to radio station
Figure 4.-Facsimlle charts sent via land line from the San Francisco Weather Service Forecast Office arereceived simultaneously at the Southwest Fisheries Center and at radio station WWD, where they arerecorded on magnetic tape. Visual Inspection Is made prior to transmission time for quality control.
WWD and to the SWFC, La Jolla,Calif., to be used for transmission ofwind and weather and sea-state forecastcharts prepared by NWS. Initially, theNWS charts were broadcast fromWWD to the tuna fleet on weekends, tofill the gap in the SWFC transmissions,and recorded weekdays at the SWFCfor evaluation and assessment of compatibility in format and in depiction ofsignificant forecast elements.
Since August 1974, the NWS FAXcharts have been broadcast from WWDdaily. Surveillance of wind and weatherconditions in the eastern tropical Pacifichas been continued at SWFC, however,to insure that supplementary verbal advisories are broadcast from stationWWD when appropriate, and to responu to direct requests from tuna vessels for information in specific situations.
[n addition to the daily wind,weather, and sea state FAX advisories,three charts depicting ocean conditionsare prepared at SWFC and transmittedby radio facsimile weekly. These are asea-surface temperature analysis, amixed layer depth analysis, and a seasurface temperature difference chartwhich compares present conditionswith those in the corresponding week ofthe previous year.
The success of the FAX program depends on continuing participation of alarge number of tuna vessel ownersand captains. The importance of takingobservations, encoding them properly,and transmitting the radio messagesmust be stressed repeatedly. On theother hand, dialogue with the fishermenis also necessary to modify and adaptthe advisory products as nearly as possible to their needs.
The weather logs and X BT recordskept aboard the tuna vessels are collected by SWFC personnel when thevessels return to San Diego. Data takenon the fishing grounds but not receivedthrough the real-time transmission system are extracted from the logs andadded to the environmental data base.
Fishing InformationCharts of sea-surface temperature
(SST) for the eastern north Pacific werepublished by the Honolulu LaboratoryofNMFS (then the Bureau of Commercial Fisheries, BCF) from 1957 through1959 in connection with a study of thedistribution of north Pacific albacore.
Responsibility for preparation of thecharts was assumed by the BCF TunaForecasting Program, San Diego, Calif.in 1960, in order to provide up-to-dateSST information to the tuna fishing industry. governmental fishery agencies,marine scientists, and meteorologists(Johnson, Flittner, and Cline, 1965).This program also undertook the compilation and publication of historical SSTdata back to 1947, in furtherance ofstudies on tuna environment (Johnson,1961; Renner, 1963).
Initially, the SST charts were issuedmonthly for the region north oflat. 200 Nand east of long. 180° and, during thealbacore fishing season. semimonthlyfor the region oflat. 25° to 52°N and eastof long. 136°W. Monthly SST plots forI-degree squares were prepared for theeastern tropical Pacific between lat. 20°Nand 200 S. The computation of themonthly and semimonthly mean temperature values, and the plotting ofthese values on base maps for analysesof the temperature fields, were doneby hand. As emphasis shifted to auto-
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matic data processing and feedbackfrom users identified additional needsfor environmental information, theanalyses were extended to include otherregions and other properties.
Fishing Jnformation now containsthe following monthly charts: a) Seasurface temperature for the easternnorth Pacific; b) Sea surface temperature for the western north Pacific; c) Seasurface temperature for the easterntropical Pacific; d) Deviations fromlong-term means of a), b), and c); e)Difference between a) and the corresponding SST field one year earlier; f)Sea level pressure and resultant wind(both current month and long-termmonthly means) for the eastern northPacific.
Fishing Jnformation also containsgraphs of subsurface temperature structure along ships' routes from Hawaii toU.S. west coast ports, narrative descriptions of the significant features ofthe charts, and articles on the albacorefishery at the beginning and end of thealbacore fishing season.
The semimonthly SST charts are nowpublished year-round as the Fishing Information supplement. During the albacore fishing season, they are accompanied by the A Ibacore Bulletin whichcontains timely information on fishingconditions and on the progress of thefishery.
I n addition to the charts listed above,a set of tabulations is produced eachmonth which contains average SST's,air temperatures. dew point temperatures, sea level pressures, cloudamounts, and resultant winds for5-degree squan:s. From these monthlyaverages of observed environmentalvariables are computed the principalcomponents of heat exchange at the seasurface, including incoming radiation,reflection, back-radiation, evaporation,
Figure 5.-Advlsory charts prepared lor radio facsimile transmission are displayed for convenient reference along with environmental charts and satellitepictures received from the Nallonal Weather Service,and Fleet Numerical Weather Central.
and sensible heat flux. The tabulationsalso contain deviations of each of theobserved and computed variables fromtheir respective long-term monthlymeans. These monthly tabulations arenot routinely distributed, but are available for on-site use by local users. Also,a preliminary run of the 5-degreeaverages is made a few days before theend of each month for use by the LongRange Prediction Group of the National Weather Service. Cooperationwith other organizations in this way offers potential benefit through progressin understanding and prediction oflarge-scale environmental fluctuations.
The computation of heat exchangecomponents from monthly averages ofobserved environmental variables givesrelatively gross estimates of heat fluxacross the sea surface. Although therehave been attempts to use such estimates in oceanic heat budget studies,their value for monitoring significant
fluctuations has not been fullyevaluated. To make the informationmore widely available, an I I-year series(1961-1971) of total monthly heat exchange has been compiled in chart formfor the eastern north Pacific, and published along with monthly mean chartsof each of the principal componentsaveraged over the same period (Clarket aI., 1974).
The principal source of data for theenvironmental charts prepared by theSWFC, other than reports from tunavessels, are the 6-hourly synoptic ship'sweather observations transmitted fromships at sea in the International Ship'sMeteorological Code and collected byNWS. The system developed by theTuna Forecasting Program in 1960 forprocessing the observations employed acomputer program which producedprinted SST summaries and otherparameters at the end of each month.The summary values were hand plotted
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and analyzed to prepare the environmental charts for Fishing Information.The original observations were savedon punched cards.
Subsequently. programs were addedor modified to produce new outputssuch as digital plots to replace thoseformerly done by hand, and specialprintouts formatted in a geographicalgrid for convenient reference. The present system provides for frequent update and ready accessibility of both current and past data on disk and magnetictape files so that operational programscan be run on schedule and specialanalyses or plots for any time period andany specified region can be run as required.
Ship-of-Opportunity Program
This program was initiated to expedite utilization of a new instrument system (the XBT) capable of augmentingsubsurface temperature monitoring andto apply the new system to create timeseries of subsurface temperature dataalong well-frequented shipping routes(Saur and Stevens, 1972). Such data areneeded for the identification, quantitative description, and understanding ofseasonal and nonseasonal changes inthe subsurface temperature structureand heat content and of mass transports(through geostrophic estimation of currents) in the upper layers of the tropicaland northeast Pacific Ocean. The program activities comprise three phases:I) Data collection. in which observations of surface salinity and of verticaltemperature profiles are made at
120-170 km intervals with expendablebathythermograph instrumentationaboard ships of opportunity; 2) Dataprocessing, in which the observationsare digitized, edited, printed for convenient reference, and added to the XBTdata base for research; and 3) Dataanalysis. in which temperature-depthsections are prepared and the observations are analyzed to depict changes insubsurface ocean conditions.
The ship-of-opportunity programstarted in 1966 with a single ship, theMatson Navigation Company's bulksugar carrier Californian, which madeabout two trips per month on the SanFrancisco-Hawaii run. The presentprogram is considerably larger and, in1974, involved three shipping companies and nine different ships. t Duringthat year the program produced 52 sections between San Francisco andHawaii, 27 sections between LosAngeles and Hawaii, 10 sections between Seattle and Hawaii, 2 sectionsbetween Alaska and Hawaii, 4 sectionsbetween Tahiti and Hawaii, and 4 sections between Samoa and Hawaii.
The program is conducted jointlywith the N MFS Pacific EnvironmentalGroup, Monterey, Calif., where thedigitization and computer analysis ofsubsurface temperature structures isperformed and through which liaisonwith cooperating ships is supervised.Responsibility for the data analysis was
'Matson Navigation Company. Chevron ShippingCompany. and Pacific Far East Line. Mention oftrade names. commercial products, or firms doesnot imply endorsement by the National MarineFisheries Service, NOAA.
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Figure 5.-Weather advisory charts can be receiveddally by fishing vessels such as this one equipped withradio facsimile recorders. Observational data receivedfrom the fishing vessels contribute significantly to theaccuracy of the advisories.
transferred from SWFC to the ScrippsInstitution of Oceanography (projectNO RPAX) at the end of 1974. The program interfaces with FNWC interests inglobal monitoring of subsurface temperature on a real-time basis and withacademic interests in understanding theprocesses of air-sea interaction andfluctuations in oceanic heat storage.The program receives support fromFNWC, in the form of computer timeand expendable probes, and from theNational Science Foundation and theOffice of Naval Research through project funding.
FNWC has supported the installationof X BT systems on merchant, fishing,and research vessels to supplementthose on naval ships in order to obtainbroad geographical coverage with sampling intervals sufficient to resolvelarge-scale oceanic features. Fordefinition of mesoscale eddies, whichhave come under recent investigationby oceanographers and may be important in connection with transient oceanfronts, much finer sampling is required.Such sampling can be carried out frommerchant ships only when project observers are aboard. The N MFS program has endeavored to maintain an intermediate sampling interval sufficientto identify transition zone characteristics between water masses and to revealsignificant fluctuations along repeatedtracks.
Figure 7.-Some fishing vessels are equipped with expendable bathythermograph systems. Temperaturesensing probes, released from a hand-held launcher. send data back to the vessel through fine conductorwires as they descend through the water.
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Ancillary Information Sources
In establishing capability for monitoring environmental conditions of concern to fisheries, SWFC has become anacquisition center for real-time environmental information in a variety offorms. Analyses and forecasts of subsurface. surface, and upper air conditions are received daily over the FNWCtie-line and plotted as charts on CalComp plotters. A similar array of products is received over the NWS facsimile circuit. The NWS circuit alsocarries gridded satellite pictures frompolar-orbiting and geostationaryweather satellites. These pictures areparticularly useful in determining thelocation and configuration of the ITCZand in following the development oftropical storms. SWFC also can receivepictures transmitted directly from the
polar-orbiting satellites on nearby orbitswhich occur twice each day. The satellite pictures, oceanographic andmeteorological analyses, and forecastcharts are displayed on the chart boardin the: environmental data room for convenient reference by environmentalanalysts, other SWFC staff, and visitors. The daily proximity of current environmental charts helps the analyst become attuned to the time and spacescales of real-time events and developinsights which can lead to new approaches in the investigation of theocean-atmosphere system.
Weather satellites have great potential for ocean monitoring, and the National Environmental Satellite Servicehas spent considerable effort in the interpretation of data from scanningradiometer infrared sensors to determine sea-surface temperatures. AI-
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though significant problems exist, oneof the foremost being cloud contamination, this effort appears certain to leadto useful application, and growing consideration has been give to ways of incorporating this information into theroutine SST analyses. The SWFC hascooperated with the Inter-AmericanTropical Tuna Commission, throughuse of the direct readout satellite receiving system, in studies to evaluate thefeasibility of using data from scanningradiometer sensors aboard NOAAsatellites to discern oceanic fronts andto apply satellite data to problems offishery oceanography (Stevenson andMiller, 1974).
APPLICATION TO FISHERIES
The purposes underlying SWFC'sinvolvement in environmental monitoring, through the programs described inthe preceding section, are to contributeto the development of the real-timefishery prediction capability and effective resource management. A fisheryprediction and management systemshould accomplish two basic functions:I) Help maintain the fishery at a level ofabundance consistent with optimumyield and recoverability from adverseenvironmental conditions or excessivefishing pressure; and 2) Increase theefficiency of harvesting, through prediction of distribution and availability, inorder to maintain a viable fishery thatcan deliver fishery products to the consumer at an economical and competitiveprice. By strengthening the total environmental monitoring effort in areaswhich are important to fisheries, the potential benefit of research in relationships between the environment andfisheries is enhanced.
Environmental data taken by tropicaltuna fishermen on the fishing grounds inthe eastern tropical Pacific during1971-1974, as a direct result of the FAXprogram, are shown in Table I. Thesedata are being utilized in ongoing research on the relationship between environmental parameters and fishingsuccess.
The FAX program contributes to theefficiency of harvesting by meeting theneeds of tropical tuna fishermen for information on weather and ocean conditions. Interviews with 22 skippers andnavigators were conducted betweenDecember 1973 and March 1974 to obtain the fishermen's evaluation of the
MFR Paper 1174. From Marine Fisheries Review, Vol. 38, No.2, February1976. Copies of Ihis paper, in limited numbers, are available from 0825,Technical Information Division. Environmental Science InformationCenter, NOAA, Washington, DC 20235. Copies of Marine Fisheries Revieware available from Ihe Superintendent of Documents, U.S. GovernmentPrinting Office. Washington, DC 20402 for $1.10 each.
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The last category includesmeteorologists, military oceanographers, marine suppliers, librarians,trade journal publishers, and others.The survey revealed that the charts areused primarily for fishing strategy bycommercial and sport fishermen, forplanning by processors, for fishery research by fishery managers, and for environmental research and teaching bymarine scientists, meteorologists, andeducators. The survey indicatedgreatest interest in the SST charts forthe eastern north Pacific; however, allof the environmental charts receivedfavorable response.
Overall, the response to the questionnaire affirms that the program is accomplishing its original objectives. Itbenefits the industry by providing usefulenvironmental information and contributes to potential advances in fisheryprediction by benefiting environmental
charts are copied by about a dozen vessels equipped with FAX recorders byAFRF. As with the tropical charts,they provide the fisherman with environmental information applicable tofishing strategy. and also support thework of the albacore investigations inmodeling the albacore fishery.
The series of monthly andsemimonthly charts of sea surfacetemperature and other environmentalfields, published in Fishing Informationand its Supplemenl. go back as far as1960. They are sent to a distribution listof some 1,196 individuals, organizations, institutions, and agencies, someof whom receive copies for further distribution. In order to assess the impactand utilization of these charts, recipients were asked to fill out and return abrief questionnaire distributed with theNovember 1973 issue. A total of 575questionnaires were returned. They reveal the following breakdown by userclassification:
Table 1.-Summary of marine observations,1971-1974.
TotalYear Weather BATHY observations Boats
Collected by radio station WWO
1971 '844 684 1.528 3-251972 2.150 498 2.648 39-531973 2,579 570 3,149 55-571974 2.178 408 2,586 61-63
Total 7,751 2.160 9,911
Collected from weather and BATHY logs
1971 ---' 886 ---' 3-251972 2.610 665 3.275 39-531973 5.167 1,160 6.237 55-57
'1974 3.265 616 3.881 61-63
Total 11,042 3.327 14,369
lWWD did not collect weather observations on a regularbasis until September of 19712Weather observations from fishing vessels were integrated into the monthly deck of synoptic observationsand not separately accounted for.31974 figures are based on projections pending receiptof all of the 1974 data.
FAX products. Nearly all of those interviewed indicated that they copied theFAX charts every day, if possible, andlistened to the verbal advisories broadcast on weekends when severe wind orweather conditions were expected.
The information regarded as mostvaluable is the location and expectedmovements of chubascos (tropicalstorms) and of extreme wind conditionssuch as occur in the Gulf of Tehuantepec. Sea and swell advisories and thesea surface temperature charts wererated next in value for aid in decidingwhen and where to fish. The mixedlayer depth charts are being copied bymost of the vessels, judging from thesample response, but were given a highvalue rating in only a few cases. Thesecharts represent an effort to furnish environmental information to thefisherman on a provisional basis andthereby enlist his participation in developing the potential application ofsuch information to fishing strategy.The charts also form a time series depicting weekly changes in oceanographic features. which may induceshort-term variations in fish behaviorand distribution.
The FAX program also provides aservice to the albacore fishery throughweekly transmission of sea surfacetemperature charts covering the albacore fishing grounds. This activity contributes to the joint research effort of theSWFC Albacore Research Investigation and the American Fishermen's Research Foundation (AFRF). These
User classification
Commercial fishermenProcessors and distributorsSport fishermenFishery managersMarine scientistsTeachersOther
Percent oftotal returns
3839
10161014
and fishery research. It should be notedthat the preparation and distribution ofenvironmental charts by this program isa unique undertaking, and to some degree, provides the only generally available source of quasi-current information on abnormal conditions, such as EINino occurrences. The SWFC receivesnumerous inquIrIes during suchanomalous events concerning the statusand tendency of environmental conditions.
Although much work has been doneon the relation of fish to environmentalconditions, the problem has hardly beenscratched. An intensive and long-rangeresearch effort must be sustained to determine the specific extent and nature ofenvironmental control on the distribution, survival, and behavior of fish. Asimilar effort must be made to understand the forces that produce environmental fluctuations which may havesignificant effects on a population. Suchefforts must be supported by a comprehensive monitoring of the oceanatmosphere environment and by reliable assessments of sizes and locationsof populations. Only when adequate descriptions of relevant environmentalfields are available along with adequatedescriptions of fish stock distribution,can the knowledge of environmentalprocesses and of behavioral responsesto such processes be applied effectivelyin a fishery prediction system to controlthe fishery.
LITERATURE CITEDClark. N. E.. L. Eber. R. M. Laurs. J. A. Renner,
and J. F. T. Saur. 1974. Heat exchange betweenocean and atmosphere in the eastern northPacific for 1%1-71. U.S. Dep. Commer..NOAA Tech. Rep. NMFS SSRF-682. 108 p.
Johnson. J. H. 1961. Sea surface temperaturemonthly average and anomaly charts northeastern Pacific Ocean. 1947-58. U.S. Fish Wildl.Serv .. Spec. Sci. Rep. Fish. 385.56 p.
Johnson. J. H .. G. A. Flittner. and M. W. Cline.1965. Automatic data processing program formarine synoptic radio weather reports. U.S.Fish Wildl. Serv.. Spec. Sci. Rep. Fish. 503,74 p.
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