NOAA Technical Memorandum NMFS 

I 

i 

May 1981 

OBSERVATIONS OF ALBACORE (Thunnus alalungs) FISHING OFF 

CALIFORNIA IN RELATION TO SEA SURFACE TEMPERATURE ISOTHERMS 

AS MEASURED BY AN AIRBORNE INFRARED RADIOMETER 

James L. Squire, Jr. 

NOAA-TM-NMFS-S W FC- 1 1 

U.S. DEPARTMENT OF COMMERCE 

National Oceanic and Atmospheric Administration 

National Marine Fisheries Service 

Southwest Fisheries Center 
NOAA Technical Memorandum NMFS 

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May 1981 

OBSERVATIONS OF ALBACORE (Thunnus alalungz) FISHING OFF 

CALIFORNIA IN RELATION TO SEA SURFACE TEMPERATURE ISOTHERMS 

AS MEASURED BY AN AIRBORNE INFRARED RADIOMETER 

James L. Squire, Jr. 

Southwest Fisheries Center 

National Marine Fisheries Service, NOAA 

La Jolla, California 92038 

U.S. DEPARTMENT OF COMMERCE 

Malcolm Baldrige, Secretary 

National Oceanic and Atmospheric Administration James P. Walsh, Acting Administrator 

National Marine Fisheries Service 

Terry L. Leitzell, Assistant Administrator for Fisheries 
TABLE OF CONTENTS 

ii 

1 

3 

4 

6 

7 

Abstract ........................... 

Introduction ......................... 

Methods ........................... 

Results and Discussion .................... 

Literature Cited ....................... 

Figures.. ..... .'. ................... 

i 
OBSERVATIONS OF ALBACORE (THUNNUS ALALUNGA) FISHING OFF 

CALIFORNIA IN RELATION TO SEASURrACEATURE ISOTHERMS 

AS MEASURED BY AN AIRBORNE INFRARED RADIOMETER 

James L. Squire, Jr. 

Southwest Fisheries Center 

National Marine Fisheries Service, NOAA 

La Jolla, California 92038 

ABSTRACT. 

cooperation with the U. S. Coast Guard and the U. S. Navy off the United 

States west coast, the 1 ocation of a1 bacore, Thunnus a1 a1 unga (Bonnaterre) , fishing relative to sea surface temperature was recorded. 

found between albacore fishing and certain sea surface temperatures and 

discontinuities in temperature. 

fishing was observed off southern California were 17.8O to 18.9OC (64.0° to 

63.OoF); and off central California were 15.6O to 17.2OC (60.0° to 63.0°F) and 

these temperature ranges are in general agreement wi th optimum f i shi ng 

temperatures reported by other authors. On two occasions when the specific 

objective was to survey temperatures about the commercial a1 bacore fleet, 

fishing was being conducted immediately west of a temperature discontinuity. 

During airborne infrared sea surface temperature surveys,in 

An association was 

Sea surface temperatures where a1 bacore 

Further studies using the near-instantaneous airborne infrared sea 

surface and sub-surface survey techniques for temperature, in association with 

measurements of other physical and biological parameters, aided by satellite 

data, should be conducted. This would establish the true relation of isotherm 

patterns to the location and movement of the albacore fishing area for the 

ultimate development of re1 iable, tactical information for the fishing fleet 

and a better understanding of the factors determining the migration patterns 

of albacore. 

ii 
OBSERVATIONS OF ALBACORE (THUNNUS ALALUNGA) FISHING OFF 

AS MEASURED BY AN AIRBORNE INFRARED RADIOMETER 

CALIFORNIA IN RELATION TO SEASURFACE TEMPERATURE ISOTHERMS 

James L. Squire, Jr. 

National Marine Fisheries Service 

Southwest Fisheries Center 

La Jolla, Cal ifornia 92038 

National Oceanic and Atmospheric Admi ni stration 

INTRODUCTION 

It has been known for over 60 years that a general relation exists 

between certain ranges of sea surface temperature and the areas of productive 

fishing for a1 bacore, Thunnus a1 alunga (Bonnaterre) off the eastern Pacific 

coast. Thompson (1917)usedmjnimum nighttime air temperatures at sites near 

the ocean in southern California as an indication of sea surface temperature, 

and claimed a relation of higher air temperature to a larger catch. Later, 

Clemens (1961) in an analysis of catch temperatures for 1.3 million albacore 

sampled off Cal i fornia from 1954 through 1958 reported a catch temperature 

range of 13.9' to 25OC (57' to 77OF); that 90% of the fish were taken from 

water having surface temperatures of 15.6O to 19.4OC (60' to 67OF)i and best 

fishing was in the temperature range of 15.6O to 18.3OC (60' to 65 F). 

latitudes than in the southern latitudes. Powell , Alverson and Livingston 

(1952) reported that catch temperatures for 1,011 albacore caught by a 

research vessel in the oceanic areas off Oregon and Washington ranged from 

12.2' to 16.7OC (54' to 62OF) , with the greatest frequency of catch being made 

at 15.0°C (59OF). A1 verson (1961 reported that research vessel troll catches 

of albacore were highest off Oregon and Washington when temperatures ranged 

between 14.4' to 16.1°C (58' to 61OF). 

Optimum catch temperatures for albacore are usually lower in the northern 

Observations by fishermen on the association of albacore to the coastal 

sea surface temperatures off Cal ifornia have been referred to by Godsil (1949) 

and Clemens (1961). They reported that changes in surface temperature are 

often used by albacore fishermen as indicators of productive areas and that 

the optimum fishing zone for albacore appears to be the marginal areas where 

green coastal and blue oceanic (Cal ifornia Current) waters meet. Productive 

areas were reported by Clemens (1961) to be offshore along the margin of the 

upwelling area extending from near Point Conception to the Columbia River. 

Few albacore were reported being taken nearshore in the cold, upwelled water, 

and catches were reduced farther offshore. 

a1 bacore frequently abound offshore a1 ong edges of cold "tongues" or "fingers" 

of water, along margins of currents and eddies and in what appear to be large 

areas or "pools" of water in the 15.6O to 18.3*C (60.0° to 65.OoF) range well 

offshore and isolated at its boundary by either wanner or cooler water. 

Albacore in these "pools" appear to be cut off from the main migration, as 

these "pools" become smal ler , the fi sh become concentrated , and f i shermen 

sometimes find these areas productive. 

Fishermen a1 so reported that 
-2- 

Though considerable information is available on a1 bacore catch 

temperatures and general descriptions of temperature changes which appear to 

have affected the catch, the relation of albacore fishing to sea surface and 

near surface temperature, water color, and the occurrence of biological 1 i fey 

particularly forage species, and their changes over a short time scale within 

a restricted geographical fishing area is poorly understood. Pearcy's (1973) 

study of the Oregon coast showed that during some airborne infrared surveys, 

areas having albacore catches were related to temperature patterns and the 

Columbia River plume in water of 14O to 16.5OC (57.2O to 61.6OF); however, in 

other surveys a relation of albacore catch to temperature patterns was not 

evident. 

To provide better understanding of 1 arge-scal e temperature changes in the 

eastern Pacific and their relation to the albacore fishery, sea surface 

isotherm charts are issued bi-weekly as an albacore fishing aid during the 

fishing season by the National Marine Fisheries Service (Johnson, F1 ittner, 

and Cline, 1965). 

large area of the eastern Pacific and show 2 week average tempratures by lo 

latitude by longitude areas. However, these isotherm charts are not 

sufficiently detailed to permit determination of sea surface temperature 

patterns in localized albacore fishing areas on a real-time basis. 

These charts, developed from ship observation data, cover a 

The correlation of sea surface temperatures with coastal a1 bacore fishing 

would probably be greatest in areas having a large temperature gradient, or a 

large change in sea surface temperature in a short geographical distance. Sea 

surface temperature gradients off the west coast are not large when compared 

to those for other areas such as the northwest Atlantic's Gulf Stream. 

However, the major coastal upwelling zone from near Cape Blanco, Oregon to 

Point Conception, Cal ifornia has a1 on 

opportunity for comparative studies of coastal a1 bacore distribution and 

temperature patterns. During airborne infrared temperature surveys (Squire, 

1971) the largest gradient changes were observed a1 ong the central Cal i fornia 

coast, and it is in this area that most comparative observations of albacore 

fishing to temperature patterns were made. 

its boundary with the Cal i fornia Current gradients of up to 2.2OC (4.0 % F), and this area provides the best 

Information on the location of "thermal fronts", when they can be 

observed by the National Weather Service satellite off the west coast, is 

being issued to interested albacore fishermen during the fishing season as 

part of NOAA's Sea Grant Advisory Program (Gorman, 1976). Since this 

technique involves viewing the sea surface through the total earth's 

atmosphere, viewing conditions from space requires a clear airpath. Under 

"clear" viewi ng conditions, temperature errors can be expected due to changes 

in marine layer thickness and density. Unfortunately, the California coastal 

waters are frequently covered with 1 ow stratus for extended periods of time 

during the summer and fall a1 bacore fishing season, making viewing difficult 

from sate1 1 i tes. 

truth determined for satellite data during tests by Stevenson and Miller 

(1974) over the eastern tropical Pacific, report an average difference of 

1.5OC (2.7OF). 

Correction factors for sea surface tmperatures to ground 
METHODS 

Sea surface temperature can be determined rapidly and in detail by use of 

an airborne infrared radiometer, and this technique has been used with success 

in Australia to assist the southern bluefin tuna (Thunnus thynnus maccoyii) 

fishing fleet (Hynd, 1968). In the coastal eastern-Pacifc,ocations of 

albacore fishing vessels in relation to sea surface temperature have been 

observed since 1963 during similar airborne temperature surveys, and these 

observations are presented for the purpose of gaining a better understanding 

of the re1 ation of sea surface temperature within a restricted geographical 

area to the distribution of a1 bacore as represented by the physical location 

of a1 bacore fi shing. 

In August 1963, the Tiburon Fisheries Laboratory began monthly synoptic 

sea surface temperature surveys using an airborne infrared radiometer over 

continental shelf areas off Washington, Oregon, and California (Figure 11, in 

cooperation with the U. S. Coast Guard. Airborne surveys were conducted at an 

elevation of 152.4 meters (500 feet) to allow operation during periods of low 

stratus, a1 though many flights required rescheduling due to ceilings less than 

152.4 meters (500 feet). Comparisons between the airborne radiometer and a 

surface ground truth observation showed an avera e difference of 0.20°C 

deviation of 0.4OC (0.6OF) Results of the sea surface temperature surveys 

were issued monthly in isotherm-chart form and a summary report describing the 

technique and the results for 1963-1968 was issued by the U. S. Coast Guard 

(Squire, 1971). Flight tracks of these surveys during the summer and early 

fall occasionally enter the eastern edge of the normally productive albacore 

fishing area, and during the months of September and October 1963, August 

1964, August and November 1965, and October 1966, the flights passed over or 

near concentrations of a1 bacore fishing vessels. Inspection of 1 ogbook data 

for the albacore fleet indicated catches were being made in the areas where 

albacore boats were observed fishing. 

locations were noted and later plotted on isotherm charts (Figures 2-7). The 

actual catch by the a1 bacore fleet on each day observed is unknown. However, 

since there is communication between vessels, and the albacore fleet attempts 

to orient itself to locations where fishing is productive, it is assumed that 

1 ocations of vessels were good indicators of fishable concentrations of 

a1 bacore. 

(0.35OF1, and a range of -l.l°C (-1.9OF) to +0.6 8 C (+1.Z0F), and a standard 

The number of vessels and their 

To explore further the relation of albacore fishing to temperature, 

special surveys were conducted on September 11, 1970 and September 16, 1972. 

These surveys of geographical areas having concentrations of albacore fishing 

vessels were conducted in cooperation with the U. S. Navy and U. S. Coast 

Guard, respectively (Figures 8-9). 
-4- 

RESULTS AND DISCUSSION 

In the central survey area (Figures 2-6), Figures 2, 3 and 4 show 

locations of fishin vessels in relation to the warmer offshore isotherms of 

Off Bodega Bay (Figure 5) fishing observed in October 1963 was associated with 

a lobe of water greater than 16.7OC (62.OoF) surrounded on three sides by 

water of a slightly lower temperature. 

Monterey (Figure 6) fishing was associated with a sharp temperature gradient 

on the southern segment of a large warm gyre of water greater than 17.2OC 

(63.OoF) and was centered in water about 16.7OC (62.OoF). 

between 15.6O (60.0 % F) and 17.2OC (63.OoF) which tend to parallel the coast. 

During the August 1965 survey near 

Off southern California in August 1964 ( F i g u r e 7 ) both sport and 

commercial vessels fishing for a1 bacore were observed. 

was observed fishing in water having a surface temperature of about18.3 C 

(65.OoF) and were oriented along this isotherm northwestward to the limit of 

vision. 

This a1 bacore flget 

On September 11, 1970 (Figure 8) a1 bacore fishing was concentrated 

approximately 80 nautical miles west of Point Sur, California, and a total of 

80 boats were reported to be involved. A survey of this fleet concentration 

was arranged through the cooperation of the U. S. Naval Air Station, Moffett 

Fie1 d, California. During a routine offshore patrol, the surface water 

temperature in an area about the fishing fleet was surveyed. The center of 

the fleet operation was near 36'25" 1 ati tude by 123°40'W 1 ongi tude, and most 

of the boats were operating in an area about 8 nautical miles by 10 nautical 

miles, oriented in a north-south direction. The fleet center was in a 

temperature area between the 16.7OC (62.OoF) and 17.2OC (63.OoF) isotherms. 

Temperature inshore or on the east side dropped to 15.6OC (6O.O0F) within 

about 3-1/4 nautical miles, and a sharp temperature gradient or front was 

evident in the northeast portion of the survey area, with inshore temperatures 

down to 14.4OC (58.OoF) range. 

temperature increased to 17.8OC (64.OoF). 

To the west of the fleet about 4 miles the 

On September 16, 1972, during surveys in cooperation with the U. S. Coast 

Guard Air Station, San Franci sco, Cal i fornia, near the NOAA/NMFS research 

vessel David Starr Jordan, in an area northwest of Monterey Bay, California, 

the commerc-i81acoreeet was again surveyed. 

observed in the area and are shown in Figure 9 in their position relative to 

sea surface isotherms. 

and the center of the fishing fleet which was fishing in water of 15.6' 

(6O.O0F) to 16.1°C (61.0°F). 

About 29 boats were 

A tem erature gradient or front of 2.2OC (4.OoF) ranging from near 13.3O (56.0 g F) to 15.6OC (6O.O0F) was evident between shore 

From observations recorded during these surveys, it is obvious that the 

fleet is not always oriented relative to specific temperature isotherms. Off 

central California the fishery when inshore appears to be associated with 

slightly cooler temperatures of 15.5' (6O.O0F) to 16.1°C (61.OoF) to the west 

and further offshore where temperatures of 16.7' (62.OoF) to 17.2'C (63.OoF) 

were observed in the fishing area. The location of fishing operations 

immediately west of areas having a rapid increase in temperature was observed 

on two occasions. 

having a rapid change in thermal structure than to a specific isotherm. 

Areas of albacore fishing may be more related to areas 
-5- 

Current synoptic thermal front and sea surface temperature charts provide 

fishermen with general overview of two enviromental parameters which may 

indicate an infinite number of locations for albacore fishing in relation to 

thermal fronts or a specific temperature. 

caught in these locations is not known, nor is it known what the true relation 

there is between the relative importance of a ''strong" or "weak" front and 

albacore fishing. In the airborne infrared examples given in previous 

figures, albacore fishing is many times found to be associated with a 

temperature change, but not of the magnitude of a temperature "front." 

Whether or not a1 bacore can be 

There is a need to determine the true relation of surface and near 

surface temperature and temperature fronts and other physical and biological 

parameters to albacore fishing and how they may affect the movement of the 

fishery. Otherwise we will continue to see the proliferation of synoptic 

survey material on physical phenomena generated from new measuring vehicles 

such as satellites that attempt to aid a fishery but the synoptic material has 

no proven correlation with the behavior of the fish and the fishery. 

To determine if a significant correlation exists between isotherm 

patterns and the geographical occurrence of fishing (and the catch of 

albacore) over a time period, surveys should be conducted using airborne, 

surface and subsurface measurement techniques. Surveys in cooperation with 

the fleet, of fishing areas and the ocean area about them for temperature and 

biological observations at short time intervals should be of value in 

observi ng movements of a1 bacore and the associ ated fishing fl eet in re1 ations 

to changes in the sea surface and near subsurface temperature patterns, water 

color, or biological activity. These near surface measurable parameters in 

conjunction with sate1 lite data could provide a comprehensive analysis of the 

fishing area. 

surface and sub-surface isotherm patterns and other biological observations 

could be firmly established, airborne surveys combined with satellite data may 

provide a better knowledge of physical and biological parameters related to 

a1 bacore migration, and possibly a method of real-time prediction of shortterm migration within the general area of fishing, a service which would be of 

tactical value to the a1 bacore fishing fleet. 

If a relation between movement of albacore and changes in 
-6- 

LITERATURE CITED 

Alverson, Dayton L. 1961. Ocean temperatures and their relation to 

albacore tuna (Thunnus germo) distribution in waters off the 

coast of Oregon-nmand British Columbia. 

Bd. Canada 18(6):1145-1152. 

J. Fish. Res. 

Clemens, Harold B. 1961. The migration, age and growth of Pacific 

albacore (Thunnus germo) 1951-1958. Calif. Dept. of Fish and 

Game, Fi sh.,-Trr, 128p. 

Godsil , Harry C. 1949. The tunas (Hi storical review 1916-1947). Cal if. 

Dept. of Fish and Game, Fish. Bull., 74:ll-27. 

Gorman, Brian E. 1976. Those big ones won't get away anymore. U. S. 

Dept. Commerce, NOAA 6(1):29-31. 

Hynd, J. S. 1968. Sea surface temperature maps as an aid to tuna 

fishing. Aust. Fish. News Lett. 27(5):23-29. 

Johnson, James H., G. A. Flittner, and M. W. Cline. 1965. Automatic 

data processing program for marine synoptic radio reports. U. S. 

Fish Wildl. Serv., Spec. Sci. Rep. Fish. 503, 74p. 

Pearcy , Will i am G. 1973. A1 bacore oceanography off Oregon-1970. 

Fish. Bull., U. S. 71(2):489-504. 

Powell, Donald E. , Dayton L. Alverson, and Robert Livingston, Jr. 1952. 

North Pacific a1 bacore tuna exploration. U.S. Fi sh. Wil dl. Serv. , Fish. Leafl. 402, 56p. 

Squire, James L. 1971. Measurements of sea surface temperature on the 

eastern Pacific continental shelf using airborne infrared 

radiometry, August 1963-July 1968. U.S. Coast Guard, Ocean Rep. 

CG373-47, 229~. 

Stevenson, Merritt R. and F. R. Miller. 1974. Application of satellite 

I n te r- Am. 

May 1974, 

data-to study oceanic fronts in the eastern Pacific 

Trop. Tuna Comm. Final Rep. , Grant No. 04-3-158-59, 

Thompson, W. F. 1917. Temperature and the albacore. Ca 

lllp. 

Game 3 (4 ) : 153-1 59. 

if. Fish and 
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NORTHERN 

AREA 

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Figure 1. Areas covered by monthly airborne sea surface temperature surveys. 
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