U N I T 18
PA C I F I C H I G H LY M I G R AT O R Y P E L A G I C F I S H E R I E S

pacific highly migratory
pelagic fisheries
Unit

18
JOHN CHILDERSSEFSC Pascagoula Laboratory

GARY SAKAGAWA

NMFS Southwest Fisheries
Science Center
La Jolla
California
KEITH BIGELOWINTRODUCTION

Adult fishes in this group are large pelagic
predators found primarily in oceanic waters acrossthe Pacific Ocean, from the tropics to temperate
latitudes. Many of these fishes routinely travel
great distances performing trans-Pacific migrations,crossing the waters of several nations and the highseas in their pursuit of forage and ideal habitat for
reproduction. Collectively referred to as highly
migratory species, these fishes include yellowfin
tuna, skipjack tuna, bigeye tuna, albacore, blue
marlin, swordfish, dolphinfish (mahi mahi), large
pelagic sharks, and others. Many are valuable andhighly prized by both commercial and sport fishermen. The status of most tuna stocks is relatively
well known, while the status of many stocks ofthe other species is either uncertain or unknown(Table 18-1).
Fleets belonging to coastal and distant-water
fishing nations target highly migratory species
throughout the Pacific Ocean. Some of the fleetsare capable of operating across the Pacific as wellas in other oceans during a single fishing season.
These fleets use larger purse-seine nets or longline
gear, and the vessels have fish-holding capacities
of several hundred to 2,000 metric tons (t) each.
Other small fleets operate only in coastal waters
with handline, troll, gillnet, harpoon, and longline
gears and produce fresh fish for local economies andfor subsistence use. Several Pacific Island communities and nations also depend on highly migratory
species for income, largely from the sale of fishingaccess licenses to foreign tuna fishermen.

237

NMFS Pacific Islands
Fisheries Science Center
Honolulu
HawaiiPhoto above:
Very young sailfish collected
on a NMFS research cruise.

6 TH ED I T I ON
OUR LIVING OCEANS

Table 18-1
Productivity in metric tons (t)and status of Pacific highly
migratory pelagic fisheries
resources.

Recent average
yield (RAY)1

Currentyield (CY)109,987
130,836

103,322
114,247

81,35087,000

Below
Above

274,974
1,494,421

322,004
1,538,112

Unknown
2,700,000

252,412399,378

174,780
399,828

285,000
554,000

2,662,008

2,652,293

4,029,354

Albacore
North Pacific 8
South Pacific 9
Pacific bluefin tuna (Pacific)10

74,01337,602
25,10067,541
32,10824,196

Unknown
117,000
Unknown

Subtotal, temperate tunas

136,715

123,845

208,737

Black marlin (Pacific)
Blue marlin (Pacific)
Sailfish (Pacific)
Striped marlin (CWP)11
Swordfish (North Pacific)12

1,705
17,3695,153
8,065
33,0001,705
17,369Unknown
8,065
57,000Unknown
17,369Unknown
Unknown
57,000Subtotal, billfish

65,29289,29289,292

Bigeye thresher (North Pacific)
Blue shark (North Pacific)
Pelagic thresher (North Pacific)13
Shortfin mako (North Pacific)
Thresher shark (North Pacific)14

4
37,3862
69
323

Unknown
70,000Unknown
Unknown
Unknown

Unknown
Unknown
Unknown
Unknown
Unknown

Subtotal, oceanic sharks

37,78470,39870,398Species/stock

Sustainable
Stock level
yield (MSY) relative to BMSY

Harvestrate

StockstatusOverfishing

Not overfishedUnknownAbove

Not overfishing
Not overfishing

Not overfishedNot overfished

Near
Above

Overfishing
Not overfishing

Not overfishedNot overfished

Near
Unknown
Unknown

Unknown
Not overfishing
Unknown

Unknown
Not overfishedUnknown

Unknown
Near
Unknown
UnknownAbove

Unknown
Not overfishing
Unknown
Unknown
Not overfishing

Unknown
Not overfishedUnknown
Unknown
Not overfishedUnknownAbove
Unknown
Unknown
Unknown

Unknown
Not overfishing
Unknown
Unknown
Unknown

Unknown
Not overfishedUnknown
Unknown
Unknown

Tropical tunas
Bigeye tuna
Eastern Pacific2
Central Western Pacific 3
Skipjack tuna
Eastern Pacific 4
Central Western Pacific5
Yellowfin tuna
Eastern Pacific 6
Central Western Pacific7
Subtotal, tropical tunas
Temperate tunas

Billfishes

Oceanic sharks

United States fishermen have a long historyof fishing for Pacific highly migratory species. In
American Samoa, Guam, Hawaii, and the Commonwealth of the Northern Mariana Islands,handline fisheries for highly migratory species haveoperated since antiquity. Immigrants establishedpole-and-line and longline fisheries for tuna in
Hawaii and southern California in the late 1800’s
and early 1900’s. Pole-and-line fishing was thedominant fishery in Hawaii through the 1970’s,
but in the late 1980’s longline fishing for tunas expanded rapidly and diversified to include swordfish
in the 1990’s. A sizable longline fishery for albacore238

has developed in American Samoa since 1995.
Currently, U.S. fisheries targeting highly migratory
species include commercial purse-seine fisheries inthe eastern and western tropical Pacific; troll fisheries in the North and South Pacific; longline fisheries
operating out of American Samoa, California, andHawaii; troll and handline fisheries operating in the
Exclusive Economic Zones (EEZ’s) of U.S. PacificIslands; and drift gillnet and harpoon fisheries in
the West Coast EEZ.
Recreational fishermen in the 1920’s were
instrumental in drawing attention to the seasonal
availability of highly migratory species off Califor-

U N I T 18
PA C I F I C H I G H LY M I G R AT O R Y P E L A G I C F I S H E R I E SSpecies/Stock

Recent average Current
yield (RAY)1
yield (CY)

Sustainable
Stock level
yield (MSY) relative to BMSY

Harvestrate

StockstatusUnknown
Unknown

Unknown
Unknown

Table 18-1

Other Migratory Species
Dolphinfish (Pacific)15
Wahoo (Pacific)16

23,742831

23,742
831

Unknown
Unknown

Subtotal, other migratory species

24,573

24,57324,7532,926,372
145,5962,960,401

4,442,354

Total
U.S. subtotal

Unknown
Unknown

Continued from previous
page.

12004–06 average.
2U.S. portion of the RAY is 1,504 t. Status determinations are made for the entire Pacific region.
3 U.S. portion of the RAY is 9,928 t. Status determinations are made for the entire Pacific region.
4 U.S. portion of the RAY is 1,726 t.
5U.S. portion of the RAY is 55,588 t.
6 U.S. portion of the RAY is 1,749 t.
7U.S. portion of the RAY is 55,588 t.
8 U.S. portion of the RAY is 13,166 t.
9 U.S. portion of the RAY is 3,950 t.
10 U.S. portion of the RAY is 148 t.
11Central Western Pacific stock.
12U.S. portion of the RAY is 1,625 t.
13 U.S. portion of the RAY is 1 t.
14 U.S. portion of the RAY is 179 t.
15 Also commonly known as dorado or mahi mahi.

nia. Since then, sportfishing has grown in popularity and now supports important recreational
fisheries for marlins, yellowfin tuna, dolphinfish,albacore, pelagic sharks, and other species in locations such as San Diego, California. Recreational
highly migratory species fisheries also developed inother locations in the United States, such as Kona,
Hawaii. Sportfishing participants contribute several
million dollars annually to local economies.
The largest contemporary U.S. commercial
fishery for highly migratory species started off the
U.S. West Coast and Baja California, Mexico in
the 1930’s. At that time, U.S. fishermen targeted
Pacific bluefin tuna and albacore for the emerging
canned tuna market. The fishery rapidly expanded
southward and westward with the development of
new purse-seine fishing gear and discovery of large
stocks of tropical tunas (yellowfin, skipjack, andbigeye tunas). During 1976–80, expansion of thefishery was concentrated in the eastern tropical Pacific. The U.S. fleet dominated the fishery until the
1980’s, when fishing became less profitable owing
to declining catch rates and increased costs associated with domestic regulations to reduce dolphinmortality. Many U.S. fishermen quit the fisheryor moved their fishing operations to the central
western Pacific. The U.S. fleet in the eastern tropical Pacific declined to about eight vessels by 2003.
Simultaneously, the fleets of Mexico and other
Latin American nations expanded and quickly filled
the void. In 2006, 226 large purse seiners were active in the eastern tropical Pacific tuna fishery. In
2006, Ecuador (with 85 vessels) and Mexico (with57 vessels) were leaders in the fishery.
Pacific tuna fisheries east of 150˚W longitude
have traditionally been managed in accordance withrecommendations made by the Inter-American
Tropical Tuna Commission (IATTC), to which theUnited States is a party. The IATTC historically has
managed the fisheries with a focus on maintaining
the tuna stocks at levels associated with maximum
sustainable yield (MSY). The principal conservation measures have been catch quotas for yellowfin tuna. However, the IATTC has broadened
the scope of its management program to include
consideration of bycatch (including undersizedfish), fleet capacity limits, and most recently, time–area closures for purse-seine fishing. Also, for the239

Scott Landis, F/V MIDDLEPOINT

16 Average includes U.S. yield of 444 t and FAO Pacific yield of 387 t.

A SWFSC albacore troll observer. Observers collectdata on catch, effort, and various special projects aboard
commercial U.S. troll vesselsthat operate throughout theNorth Pacific.

6 TH ED I T I ON

Russell Ito, PIFSC

OUR LIVING OCEANS

Unloading tunas from thelongline vessel Gail Ann to
the Honolulu fish auction.

2005–07 fishing seasons, the IATTC agreed toa management scheme of time–area closures forpurse-seine gear and national catch quotas forlongline gear to reduce fishing mortality on yellowfin and bigeye tuna. For the 2008 fishing season
the IATTC parties were not able to reach agreement
on management measures to correct overfishing ofyellowfin and bigeye tunas. The IATTC has begun
monitoring North Pacific albacore catches as wellto ensure that the total level of fishing effort is
not increased beyond current levels. In addition,
under the Agreement on the International Dolphin
Conservation Program (AIDCP), the parties to thatagreement continued implementation of an overall
dolphin mortality limit of 5,000 animals for thefishery by distributing individual vessel quotas toqualified vessels. Furthermore, all large tuna purse
seiners operating in the eastern Pacific Ocean are
required to carry an observer to collect data oncompliance with AIDCP requirements.
In 1988, the United States and 16 South PacificIsland nations concluded a 5-year tuna fishing access agreement called the South Pacific Regional
Tuna Treaty. This treaty gave the U.S. tuna purseseine fleet fishing access to a 26 million km2 area ofthe central western Pacific Ocean in exchange forfees. In 1993, the treaty was extended for 10 years,
and in 2003 it was extended again for 10 years. The

24 0

2003 extension limits the fleet to a maximum of 40
licenses (one per vessel), plus 5 additional licenses
for joint venture arrangements with the island parties. The annual industry license fee is $3 million.
An additional $18 million is provided annually by
the U.S. government for economic assistance to theisland parties. In 2007, 18 U.S. purse seiners werelicensed to fish under the treaty.
Following 5 years of negotiations involving 24
nations, 19 Pacific nations1 adopted the Convention on the Conservation and Management ofHighly Migratory Fish Stocks in the Western andCentral Pacific (WCPFC) on 4 September 2000,
in Honolulu, Hawaii. By 19 December 2003, 13
nations2 had ratified the convention, triggering its
entry into force on 19 June 2004 and creating theWestern and Central Pacific Fisheries Commission.
The U.S. domestic procedures for ratification of
the Convention were completed in 2007, and theUnited States actively participates in the WCPFC
as a member. The WCPFC has authority to manage catch, bycatch, fishing capacity, and effort inorder to achieve its goal of conserving the stocks
and managing the fisheries for tuna and tuna-likespecies in the central and western Pacific Ocean
west of 150˚W longitude and between temperatewaters in the North and South Pacific. Means
for monitoring and compliance include a vessel
register, vessel monitoring systems, an observer
program, port monitoring, and reporting of landings, fishing effort, catch, and transshipment.
A Scientific Committee was formed when the
WCPFC entered into force to provide scientificadvice to the Commission for the Conservationand Management of Highly Migratory Fish Stocks
in the Western and Central Pacific.
While WCPFC nations negotiated terms foran overall conservation and management convention for highly migratory species west of 150˚W
longitude, two informal, international scientificarrangements have been in place in the North
1 Australia, Canada, Cook Islands, Federated States ofMicronesia, Fiji, Indonesia, Kiribati, Marshall Islands, Nauru,
New Zealand, Niue, Palau, Papua New Guinea, Philippines,
Samoa, Solomon Islands, Tuvalu, United States, and Vanuatu;
Japan and Korea voted against, and China, France, and Tonga
abstained.
2Australia, Cook Islands, Federated States of Micronesia, Fiji,
Kiribati, Marshall Islands, Nauru, New Zealand, Niue, Papua
New Guinea, Samoa, Solomon Islands, and Tonga.

U N I T 18
PA C I F I C H I G H LY M I G R AT O R Y P E L A G I C F I S H E R I E S

Pacific for a number of years. The North Pacific
Albacore Workshop was established in 1974 forexchange of scientific information useful for assessing the status of North Pacific albacore. Scientists
from Canada, Japan, Taiwan, and the United States
have participated in this arrangement. The secondarrangement, the Interim Scientific Committee for
Tuna and Tuna-like Species in the North Pacific
Ocean3 (ISC), was formed in 1995 to enhancescientific research and cooperation for conservation and rational utilization of highly migratory
species resources of the North Pacific. The ISC alsoestablishes the scientific groundwork for any future
management regime. Scientists from Canada, Japan, Korea, Mexico, Taiwan, the United States, the
IATTC, the Secretariat of the Pacific Community,
and the North Pacific Marine Science Organization
are active in this arrangement, with collaborative
scientific studies and sharing of fishery data. In thisregard, a central database and website have been
established by the ISC. At the ISC’s 2004 meeting in Honolulu, Hawaii, participants concluded
that the ISC should continue as an independent
body and be available to provide scientific stock
advice to other bodies (e.g. WCPFC, IATTC) as
needed. The ISC also decided to invite the North
Pacific Albacore Workshop to become part of the
ISC. With the addition of the albacore workshop
in 2005 as the ISC Albacore Working Group, theISC’s primary focus is now on the North Pacificstocks of albacore, bluefin tuna, swordfish, stripedmarlin, and blue shark.
In 1981, the United States and Canada enteredinto an agreement, the U.S.–Canada Albacore
Treaty, which allows for reciprocal fishing in eachparty’s EEZ and landing privileges at selected ports
for albacore fishing vessels of both countries. In
2002, that access agreement was amended to limit
access of each party’s vessels fishing for albacore in
the waters of the other party. Over a period of 3
years, the effort-limitation regime requires by thethird year no more than 125 vessels with 4 months
fishing for each, or 500 vessel-fishing months
regardless of the number of vessels involved, willbe allowed by each party in each other’s EEZ. In
3Name was changed in 2005 to the International ScientificCommittee for Tuna and Tuna-like Species in the North
Pacific Ocean.

2007, Canadian vessels fished 339 vessel months
in the U.S. EEZ, while U.S. vessels fished 22 vessel
months inside the Canadian EEZ. The agreement
also had a provision that if at the end of the thirdyear no new agreement was reached, fishing limits
would be reduced to 94 vessels for 4 months or
376 vessel-fishing months in each party’s EEZ. This
provision was implemented for 2006 and 2007.
While international mechanisms for conservation and management of Pacific highly migratory
species throughout their range are being developed,
the United States has proceeded with managing
its domestic fisheries for highly migratory species.
Lead management authority for highly migratory species rests with the Western Pacific Fishery
Management Council (WPFMC) for the U.S. EEZ
in the central western Pacific and with the PacificFishery Management Council (PFMC) for the U.S.
EEZ along the West Coast. The WPFMC has had
a Fishery Management Plan (FMP) for pelagic
fisheries since 1986. The most significant provisionof that plan is a maximum limit of 164 permits forlongline vessels operating from ports in Hawaii and60 permits for longliners operating from American
Samoa. In addition, an amendment to the plan in2001 prohibited targeting swordfish in the North
Pacific with longline gear and imposed time andarea closures for longline gear targeting tuna inorder to reduce sea turtle interaction and mortality.
In 2004, the swordfish-directed component of the
Hawaii-based fishery was re-opened but subject torestrictions on the types of hooks and bait to be
used, annual fleetwide limits on turtle interactions
and fishing effort, and other mitigation measures.
The first complete year in which the Hawaii-based
longline fishery was allowed to target swordfish was
2005. In the following year, the shallow-set longline
fishery reached the annual interaction limit of 17
loggerhead sea turtles and the fishery was closed 20
March 2006. The vessels that targeted swordfish
converted to deep-set longline and targeted tunas
for the remainder of the year. In 2007, the Hawaiibased shallow-set longline fishery stayed below theannual sea turtle interaction limit and remained
open throughout the entire year.
The PFMC began developing an FMP forWest Coast highly migratory species in 2000 andapproved the FMP in June 2003. The National
Marine Fisheries Service (NMFS) approved the

2 41

6 TH ED I T I ON
OUR LIVING OCEANS(Pacific bluefin and albacore), billfishes (marlins
and swordfish), oceanic sharks (thresher, blue,
and mako), and other species (dolphinfish andwahoo). Most of these fishes are caught commercially and support large industries. Some, such as
tropical tunas and dolphinfish, are important to
subsistence fisheries of small Pacific Island nations
and U.S. territories. Others, especially marlins,
yellowfin tuna, and albacore, support important
recreational fisheries.

Landings(x 1,000 t)
1,400
1,200
1,000
800
600
Central Western Pacific400
Eastern Tropical PacificTropical Tunas

U.S. landings

200
0
1970

1975

1980

1985

1990

1995

2000

2005

Year

Figure 18-1
Landings in metric tons (t)of skipjack tuna in the Pacific
Ocean region, 1970–2006.

FMP in February 2004 and implemented the plan
beginning in 2005. Vessels immediately affectedmost by the plan were those using drift gillnet andlongline gear. The plan prohibits shallow setting of
longline gear (used largely to target swordfish) westof 150˚W longitude because of concerns for sea
turtle and seabird interactions. In a separate action,
NMFS implemented regulations to prohibit targeting swordfish east of 150˚W longitude to prevent
jeopardy to sea turtles. Regulations protecting sea
turtles from adverse impacts of the drift gillnet
fishery had previously been announced and were
continued under the FMP; certain new closures
within the EEZ off Washington and Oregon havebeen implemented by the plan.
The United States has also taken steps to manage sharks taken in commercial fisheries. Sharkfinning (the removal and retention of shark finsonly and discarding the carcass at sea) is currently
prohibited in all U.S. fisheries. Landing shark carcasses with fins, however, is allowed at U.S. ports.
Harvest guidelines have been set for thresher sharkand shortfin mako shark by the PFMC, and thewhite shark and megamouth shark have both been
designated protected species under the plan.
SPECIES AND STATUS

Highly migratory pelagic species are oftengrouped for convenience into tropical tunas (yellowfin, bigeye, and skipjack), temperate tunas

242

Yellowfin, skipjack, and bigeye tunas are theprincipal tuna species categorized as tropical tunas.
Their concentrations are highest in the tropics
between latitudes 20˚N and 20˚S. The primaryfishing gears used to catch these tunas commercially are longlines and purse seines. Other fishinggears of less importance include ring net, handline,
troll, and pole-and-line. In 2002, more than 400
large purse seiners and more than 5,000 longliners
participated in Pacific tuna fisheries.
Longline gear is used to catch yellowfin andbigeye tunas across the Pacific, whereas the purse
seine is the primary gear used in the eastern andthe central western Pacific. In the eastern Pacific,
the largest purse-seine fleets are from Ecuador,
Mexico, and Venezuela. In the central-western
Pacific, Japan, the Republic of Korea, the Philippines, Taiwan, and the United States have major
purse-seine fleets. Major longline fleets fishingfor yellowfin and bigeye tunas are based in Japan,
Korea, and Taiwan.
Skipjack tuna is the volume leader in the Pacificand is caught primarily with purse-seine gear. The
catch is used primarily as raw material for canning.
Recent average annual yield (2004–06) is 274,974
t for the eastern Pacific and 1,494,421 t for thecentral western Pacific (Table 18-1, Figure 18-1).
The U.S. Pacific-wide catch of skipjack tuna has
averaged about 57,314 t recently. The dockside
ex-vessel revenue of the total Pacific catch is about$869 million annually. The skipjack tuna stocks are
believed to be underutilized, with the MSY for thecentral western stock at 2.7 million t; MSY for theeastern Pacific stock is unknown.
Yellowfin tuna is another prized species usedprincipally for canning. Recent average yieldU N I T 18
PA C I F I C H I G H LY M I G R AT O R Y P E L A G I C F I S H E R I E S

is 252,412 t for the eastern Pacific fishery and399,378 t for the central western Pacific fishery(Table 18-1, Figure 18-2). The U.S. catch has averaged 57,337 t in recent years. The ex-vessel value ofthe Pacific-wide catch is about $474 million. The
eastern stock of yellowfin tuna is near the biomass
that produces the MSY, but the stock is experiencing overfishing. The central western stock is slightly
above the biomass for MSY.
Large-sized bigeye tuna are sold mainly as raw
material for the high-priced restaurant trade, particularly sushi restaurants. However, landings by purse
seiners of smaller sizes, or subadults, are largely used
for canning. Recent average yield for the entire
Pacific is about 240,824 t, up significantly fromearlier yields owing to increased catches by purse
seiners taking young fish with fish-aggregating
devices (Figure 18-3). The ex-vessel revenue fromthe total bigeye tuna catch is about $1 billion annually. Most of the catch is taken by longline fleets ofJapan, Korea, and Taiwan. The U.S. catch of about
11,432 t annually is taken mostly with purse seines.
However, U.S. longliners catch about 4,000 t annually, valued at about $20 million that includes asignificant catch by Hawaii-based longliners. The
recent average yield for U.S. longliners is 317 t in
the eastern Pacific.
The MSY and current yield for bigeye tunaare undergoing review. The stock structure of the
Pacific-wide population is unclear. However, current best estimates of yield potential indicate thatthe stocks (especially the stock or stock portionin the eastern Pacific) are at full utilization, andoverfishing may be occurring.

Landings(x 1,000 t)
600

500

400
Central Western Pacific300

100
U.S. landings

0
1970

1975

1980

1985

1990

1995

2000

2005

Year
Figure 18-2
Landings in metric tons (t) of
yellowfin tuna in the Pacific
Ocean region, 1970–2006.

Landings(x 1,000 t)
150
Eastern Tropical Pacific
125

100

75

Central Western Pacific50

25

U.S. landings

0

Temperate Tunas

Pacific bluefin tuna and North and South Pacificalbacore are categorized as temperate tunas. They
generally occur in large concentrations in higher
latitudes of the North and South Pacific. Adults,
however, seasonally migrate to tropical waters forspawning.
U.S. catches of Pacific bluefin tuna have recently
been relatively minor. This species is taken seasonally off southern California and Baja California,
Mexico, primarily by purse seiners that normallytarget other species (anchovy, sardine, and mackerel) and by recreational fishermen. In the mid North

Eastern Tropical Pacific

200

1970

1975

1980

1985

1990

1995

2000

2005

Year

Figure 18-3

Pacific, Pacific bluefin tuna are taken sporadicallyby the Hawaii- and California-based longline fleetstargeting swordfish and bigeye tuna. Recent Pacificwide average (2004–06) yield is about 25,100 t.
Approximately 63% of the landings are taken by
Japan, 7% by Taiwan, 24% by Mexico, 3% by
Korea, and 2% by the United States. Stock statusis uncertain and undergoing review.
In the North Pacific, albacore are fished primar-

24 3

Landings in metric tons (t)of bigeye tuna in the Pacific
Ocean region, 1970–2006.

6 TH ED I T I ON
OUR LIVING OCEANS

Landings(x 1,000 t)
150

125

100

75

North Pacific50
South Pacific25

U.S. landings

0
1970

1975

1980

1985

1990

1995

2000

2005

Year

Figure 18-4
Landings in metric tons (t) of
albacore in the Pacific Ocean
region, 1970–2007.

Landings(x 1,000 t)
40

Entire Pacific30

Based on a dockside price of $1,973 per ton, theannual ex-vessel revenue of the 2004–06 average
North Pacific albacore yield was about $142 million
per year. The MSY is unknown. The status of theNorth Pacific albacore population is reviewed on an
ongoing basis by an international team of scientists
through the ISC’s North Pacific Albacore Working
Group. A comprehensive review was conducted in2006. Although a stock assessment was conducted
and a suite of candidate biological reference points
have been documented, management bodies (e.g.,
PFMC and WPFMC) have not established formal
harvest control rules to date.
In the South Pacific, fisheries for albacore are
expanding with largely longline and troll gears.
The 2004–06 average yield was 37,602 t (Figure18-4). Longline fleets from Japan and Taiwan are
the largest producers. Longline gear accounts for
86% of the catch and is the gear of choice for new
vessels entering the fisheries. The newer vessels use
a large reel with miles of monofilament main line.
South Pacific Island countries (French Polynesia,
New Caledonia, Fiji, and Samoa), for example,
are rapidly building significant longline fleets foralbacore. The U.S. fishery, which primarily consistsof longliners and troll vessels, landed approximately
3,950 t of albacore in the South Pacific in 2004–06.
The troll fishing season is the austral summer (November through April) in the higher latitudes (35°to 45°S) east of New Zealand.

20

Billfishes
10
U.S. Central Western Pacific
U.S. Eastern Tropical Pacific
0
1970

1975

1980

1985

1990

1995

2000

2005

Year
Figure 18-5
Landings in metric tons (t)of swordfish in the Pacific
Ocean region, 1970–2007.
Data are not available forsome recent years.

ily by longline, pole-and-line, troll, and up until
1992, drift gillnet gears. Longline gear is used in thelower latitudes and off the Japanese archipelago andcurrently accounts for 35% of the catch. Pole-andline and troll gears are used in the surface fisheries
that operate in the North Pacific Transition Zone
and higher latitudes. These gears account for 60%of the catch. The 2004–06 average yield was 74,013
t, and the U.S. yield was 13,166 t (Figure 18-4).

24 4

Billfishes, including swordfish, marlins, andspearfish, generally range from North America
to Asia and between the North and South PacificConvergence Zones. These fishes are more abundant near islands, continental slopes, seamounts,
and oceanic fronts, and many are important to local
economies. They are caught by foreign and U.S.
recreational and commercial fishermen.
Swordfish are distributed throughout thetemperate, subtropical, and tropical waters of the
Pacific. Much of the Pacific-wide catch of swordfish is taken by the Japanese longline fishery as
bycatch while targeting tunas. Other longline fleetstarget swordfish, particularly the longline fleets of
the United States, Mexico, Chile, and Australia.
Coastal swordfish fisheries occur off the United

U N I T 18
PA C I F I C H I G H LY M I G R AT O R Y P E L A G I C F I S H E R I E SLandings(x 1,000 t)
25
Entire Pacific
20

15

10

5
U.S. Central Western Pacific
0
1970

1975

1980

1985

1990

1995

2000

2005

Year

Figure 18-6

however, is estimated to be greater than the current yield.
Other Pacific billfish species include blue,
black, and striped marlins; sailfish; and shortbill
spearfish. U.S. commercial fishermen primarily use
longline, troll, and handline gears to catch marlins
and spearfish, while recreational fishing gears include rod-and-reel and handline. The U.S. catchof blue and striped marlin is worth about $2,500
per ton ex-vessel.
Blue marlin are one of the most important big
game fish for recreational fishermen and are of great
economic value to communities with charter fleetsand fishing tournaments for this species. It is also an
important commercial species. Pacific-wide commercial yields of blue marlin increased in the 1970’s
and fluctuated between 16,000 t and 22,000 t in
the 1980’s and 1990’s (Figure 18-6). Annual U.S.
Pacific fisheries yields of blue marlin increased in
the 1970’s and 1980’s and leveled out in the 1990’s
at 700 to 900 t, comprising about 4% of the Pacifictotal. Concern over the status of blue marlin has
prompted several recent efforts to assess the statusof the Pacific-wide stock. Earlier, scientists had
suggested that the stock might be overfished, asPacific-wide fishing effort increased in the 1980’s
and yields remained level. However, the most recent
assessment models indicate that effective fishingeffort for blue marlin has not increased very muchsince the early 1980’s, and at most, blue marlin are
now thought to have a biomass close to the level

24 5

Landings in metric tons (t)of blue marlin in the Pacific
Ocean region, 1970–2007.
Some recent years of data
are not available for all metrics.

Anne Allen, SWFSC

States, Japan, Taiwan, Mexico, Chile, and Australia,
using various surface gears, such as harpoons anddriftnets. Yields increased throughout the 1980’s
and fluctuated in the 1990’s (Figure 18-5), averaging about 33,000 t in recent years (Table 18-1).
Until recently, a substantial fraction of the
Pacific catch of swordfish was harvested by the
U.S. longline fleet in the central western Pacific(Figure 18-5), and prior to prohibition of the gearin 1993, some of the catch was caught by high-seasdrift gillnet vessels. The rest of the swordfish yieldis largely taken by surface gears, such as harpoons,handlines, and coastal drift gillnets. From 1989 to
1993, production from the U.S. domestic longline
fishery in Hawaii increased rapidly, reaching 5,925
t and an ex-vessel revenue of $26.1 million in 1993.
Production from the Hawaii fishery accounted forabout 14% of the total Pacific production in the
1990’s. The swordfish production from the U.S.
domestic gillnet and harpoon fisheries located primarily off California increased markedly between
1975 and 1985, when a peak yield of 3,400 t waslanded. Production from these sources declinedin the 1990’s, while production increased from
longline vessels based in California and withseasonal participation by vessels from the Hawaiibased fleet making landings in California. The U.S.
eastern Pacific fishery has a recent average annual
yield of about 1,400 t worth about $6 million in exvessel revenue. Both the U.S. longline and gillnet
fisheries have recently been affected by concerns
over interactions with protected species. In 2001,
the Hawaii-based longline fishery was prohibitedfrom using shallow-set fishing methods that target
swordfish, due to high bycatch rates of primarily
loggerhead and leatherback sea turtles. This fishery was reinstated in 2004 with new gear, fishingeffort, and turtle take limitations. Annual catches
in the Hawaii-based fishery during 2001 and 2002
declined to about 225 t due to the regulations prohibiting swordfish fishing. The catch and effort of
the California gillnet fishery also plummeted owing
to expansion of area and season closures to reduce
pinniped and turtle interactions.
The stock structure and status of Pacific swordfish stocks are unclear. Several studies suggest
more than one Pacific stock. A stock assessmentof a North Pacific population indicated a decline
in abundance in the northwest Pacific. The MSY,

Mako shark.

6 TH ED I T I ON
OUR LIVING OCEANS

Catch(x 1,000 t)
250

200

150
Total catch
100

50
U.S. catch
0
1975

1980

1985

1990

1995

2000

Year

Figure 18-7

that supports the MSY (Table 18-1). The status of
most other billfish species stocks is unknown or
uncertain, although earlier assessments using data
through 1985 indicated that striped marlin were
underutilized.

Landings in metric tons (t) ofblue shark in the North Pacific
Ocean region, 1970–2000.

Allen Shimada, NMFS

Oceanic Sharks

A freshly landed wahoo on
the deck of a NOAA Fisheries
Research Vessel.

Pacific oceanic shark species include requiem,
thresher, and mackerel sharks. Sharks are taken bylongline in the central North Pacific and by drift
gillnet off the U.S. West Coast. Shark prices vary
greatly by product form, and until recently mostlandings in U.S. fisheries were from the Hawaiibased longline fishery in the form of shark fins,selling for about $40,000 per ton. Shark finningwith discarding of the carcass at sea is currently
banned in all U.S. fisheries. Limits on non-blue
shark landings are being considered for Hawaiibased longline vessels. In Hawaii, whole sharks are
sold for about $1,400 per ton.
All pelagic longline fisheries catch appreciable
numbers of sharks, but only a few nations reporttheir shark catches. Most foreign longline fisheries
collect shark fins to produce a dried product formaking soup. The product is marketed primarily
through Hong Kong. In some cases, shark finningis conducted by fishing crew members as a separate enterprise from the primary fishery. Because
carcasses are discarded at sea, shark catches areoften treated as discards and are seldom logged;

24 6

hence, the total Pacific harvest of pelagic sharks
is unknown.
Blue sharks are the most numerous shark species in the North Pacific, and research to estimate
yield based on data reported by a subset of fishingvessels has recently allowed an assessment of blue
shark to be completed. Estimated yield of sharks(including discards) reached high levels during theera of the North Pacific drift gillnet fishery, which
ended in the early 1990’s (Figure 18-7). After aninternational ban on high-seas drift nets, the annual shark yield (mostly by longliners) stabilized ataround 33,000 t (weight estimated from number
caught multiplied by an assumed average weight of
45 kg per shark). The U.S. North Pacific yield (estimated round weight, including discards) was taken
mainly by Hawaii-based longliners and peaked atabout 6,800 t in 1993. Yields subsequently declined
as the fleet altered its fishing strategy in the mid
1990’s, but shark landings continued to increase
through 1999 (Figure 18-7) because an increasing
fraction of the yield was landed in the form of fins(landings expressed as round weight regardless of
product form). The recent North Pacific blue sharkstock assessment estimated an MSY of about twice
the recent annual yield and indicated that the stockis underexploited. In 2003, a regional MSY and
optimum yield were calculated for the U.S. Pacific
Coast stock of thresher shark, with harvest guideline established at 340 t per year. The condition ofother pelagic shark stocks remains unknown.
Other Migratory Species

Other Pacific highly migratory species include
wahoo and dolphinfish (mahi mahi). These species
are primarily caught commercially using longline,
troll, and handline gears; recreational fishermen use
mainly rod-and-reel and handlines. The U.S. catchof dolphinfish and wahoo is worth about $4,200
per ton. The MSY and status for these stocks is
unknown, but both species are thought to be near
the biomass level that would produce the MSY.
ISSUESManagement Concerns

Growth of total fleet fishing capacity for highlyU N I T 18

migratory species in the Pacific is of increasing
concern to fishery managers, because many of
the target species are already fully harvested or
harvested above sustainable levels. In addition, theeconomic impacts of high capacity are becoming
more apparent. Regional fishery management organizations and nations are increasingly considering
management and limitation of fishing capacity as amajor component of a rational fishery conservationand management program. The paradigm is that
if fishing capacity can be managed effectively, theneed for more restrictive, complicated, and costly
management measures (e.g. limitations on fishingeffort, catches, sizes, seasons, and area closures)
would not be necessary. Therefore it is prudent
to manage capacity rather than to limit efficiency.
In recent years, the IATTC has been working on
limiting purse-seine fishing capacity in the eastern
Pacific, and parties involved in developing the
WCPFC consider limitation of fishing capacity asa priority topic for consideration.
Closely aligned with fishing capacity is the problem of illegal, unreported, and unregulated (IUU)
fishing by vessels that operate outside the controlof regional management regimes. In June 2001,
the U.N.’s Food and Agriculture Organization
Council adopted an international plan of action toprevent IUU fishing. The IATTC has been actively
addressing this issue, and the emerging WCPFC
deliberated on this issue as part of the groundworkfor establishing the Commission for the Conservation and Management of Highly Migratory Fish
Stocks in the Western and Central Pacific.
Another issue in the Pacific is the high fishingmortality (and subsequent reduction in future
spawning biomass) being exerted on juvenile bigeye and yellowfin tuna with increasing use of fish
aggregating devices by purse seiners and domestic
fisheries of the Philippines and Indonesia. The
WCPFC, in collaboration with the Secretariat of
the Pacific Community, has initiated a program to
document the level of mortality, particularly thatcaused by the Philippine and Indonesian fisheries,
for highly migratory species. The IATTC has also
been addressing this issue with proposed measures
to limit the catch of bigeye tuna and to prevent
overall fishing effort from increasing, but conservation measures for 2008 to address overfishing havenot been adopted.

Mark Conlin, NMFSPA C I F I C H I G H LY M I G R AT O R Y P E L A G I C F I S H E R I E S

Bycatch and Multispecies Interactions

Of continuing concern is the bycatch of seabirds, sea turtles, and marine mammals by fisheries
for Pacific highly migratory species. NMFS has
been and will continue to be a strong proponent
for accurate reporting of catches of bycatch species as well as for adoption of preventative andmitigative gear and procedures. In this regard,
NMFS is promoting the international adoption offishing gear and techniques (i.e. large circle hooks
and mackerel-type bait) developed in the Atlantic
Ocean and currently being implemented in the Hawaii-based longline fishery to significantly reduce
turtle bycatch in swordfish fishing. The IATTC
and the Standing Committee on Tuna and Billfish
have had a working group to address the problem
of bycatch of protected species as well as incidental
catches of fishes for a number of years. A similar
working group was established by the WCPFC at
its inaugural meeting in December 2004.
Participants in various fisheries under the WPFMC’s jurisdiction continue to voice concern about
the impacts of competing fisheries on their fishingsuccess (for example, near-island troll and handliners complain about offshore longline and handline
fishing, particularly now as handline fishing around
privately deployed fish aggregating devices expands
offshore into waters fished by longliners). Also,
longline fishery participants object to the number
and severity of management measures specific to247

Blue shark in the Southern
California Bight, an important nursery area for young
blue sharks.

6 TH ED I T I ON

Allen Shimada, NMFSOUR LIVING OCEANS

Removing the hook from a
freshly landed juvenile yellowfin tuna.

that fishery. In particular, regulations to protect sea
turtles and seabirds are contested in the Hawaiibased longline fishery because the impact of thatfishery is believed to be slight compared to that ofother fisheries, particularly foreign longliners that
continue to operate unhindered on the high seas.
Transboundary Stocks and Jurisdiction

Although they fish the same resources as the
Hawaii-based vessels and sometimes fish the same
areas, longline vessels operating out of California
have not been subject to the management regulations developed by the WPFMC. As noted earlier,
however, in 2004 the PFMC approved and implemented a highly migratory species FMP to close
this loophole. The plan requires California-based
longline vessels fishing highly migratory species on
the high seas to follow practices applied to longliners by the WPFMC for prevention of sea turtle andseabird interactions. Combined with a separate
regulation issued by NMFS, the FMP results in aprohibition of all shallow swordfish longline sets byWest Coast-based longline vessels. The PFMC isconsidering whether to amend its FMP to require
the same gear and techniques as in the WPFMC’s
FMP and thus restore some swordfish fishing opportunity for the longline fleet. Other provisionsof the PFMC’s plan apply to conservation of shark
resources and involve application of existing state
regulations.
International cooperation and conservation

24 8

measures are a growing management issue emerging for the highly migratory species FMP of the
PFMC. If a tuna stock is experiencing overfishingor becomes overfished, FMP regulations could
result in limits on the catch of U.S. fishermen,
even when the regulations result in no significant
advantage to the stock because of the relatively
small amount of effort exerted by the U.S. fleet.
The FMP regulations would have no effect on thesubstantial amount of foreign fishing that occurs
on the high seas, although this sector of the fisheryfor highly migratory species may be the root causeof overfishing. United States fishermen would thus
be disadvantaged. Efforts of the United States inestablishing the WCPFC and strengthening the
IATTC are designed to ensure that conservation
measures would be equally applied to foreign and
U.S. fishermen.
An administrative problem arising in all areasin the Pacific is the increasing need for vessel records and statistical documents for shipments ofvarious tuna from nation or region to nation or
region. Fish are easily shipped across regions, andall nations have a stake in ensuring that fishermen
are not allowed to circumvent catch restrictions
in one area by simply shipping fish to other areas
and reporting they were caught there. While cumbersome, catch documentation requirements are
increasingly needed to support effective conservation and management of important stocks in the
Pacific Ocean.
Scientific Advice andAdequacy of Assessments

The condition is unknown for populations ofsome of the billfishes, dolphinfish, wahoo, andmost shark species, largely because of a lack ofcomprehensive data on these species, in particular
fishery statistics from all fishing fleets. Many of thespecies with unknown status are not targeted inhighly migratory species fisheries but are captured
as incidental catch or bycatch. United States fishery data collection through logbooks and observer
programs is comprehensive, but is not enoughfor performing stock assessments. These data
represent only a small fraction of the total catchfrom the stocks. Data collection and exchange
on an international scale are required. Recent as-

U N I T 18
PA C I F I C H I G H LY M I G R AT O R Y P E L A G I C F I S H E R I E S

sessments undertaken for tuna species, swordfish,
blue marlin, and blue shark have resulted frominternational collaboration. This collaborative approach also led to new stock assessment activities
and a re-examination of stock structure for stripedmarlin in 2007. For other species, particularly
bycatch species, international data collection mustbe significantly improved before credible stock assessments can be performed.
The take of protected species by U.S. fisheries
is well monitored, and aggressive management
measures have been taken to minimize the impacts of U.S. fisheries. However, the impacts of
U.S. fisheries on protected species and bycatch ingeneral are relatively minor compared to those of
the much larger foreign fleets that fish across the
Pacific, because they represent only a small fraction of total fishing effort. Further work on aninternational scale will be required to minimize
these impacts.
The U.S. monitoring of landings (including
estimation of total catches), collection of fishingeffort and resulting catch data (logbooks), and size
data for domestic coastal and high-seas fisheries
provide the basis for preparing scientific advice on
domestic fisheries. They also comprise a disproportionate amount of the data used by international
bodies for stock assessments. At meetings of multinational management bodies, NMFS will continue
to strongly advocate participation of all fishing nations to meet their obligations for monitoring theirfleets commensurate with their fisheries production. Data collected ought to be shared and madeavailable to international management bodies andscientific working groups tasked to conduct stock
assessments and to provide advice on the conditionof the highly migratory species stocks.

statistics, evaluate fishery developments, and assess
the condition of the western and South Pacificstocks. The recent assessments of North Pacificswordfish and blue shark were undertaken cooperatively under the sponsorship of the ISC. This
organization now meets regularly to organize suchresearch. The eastern Pacific stocks are assessedannually by the IATTC for providing fishingmanagement advice.
Management of the domestic fisheries has
been successful in reducing gear conflicts among
longline, troll, driftnet, rod-and-reel, and handline
fisheries and in reducing U.S. fishery impacts on
Hawaiian monk seals, California sea lions, cetaceans, albatrosses, and sea turtles. Although theswordfish sector of the Hawaii longline fishery wasclosed between April 2001 and April 2004, thetuna harvest by the fishery continued to increase
throughout the 1990’s and early 2000’s.
FOR FURTHER READING
Boggs, C., P. Dalzell, T. Essington, M. Labelle, D. Mason,
R. Skillman, and J. Wetherall. 2000. Recommended
overfishing definitions and control rules for the Western
Pacific Regional Fishery Management Council’s pelagic
fishery management plan. NMFS Southwest Fisheries
Science Center, Honolulu Laboratory Administrative
Report H-00-05, Honolulu, HI, 18 p.
Childers, J. 2001. Summary of the 2000 U.S. North andSouth Pacific albacore troll fisheries. NMFS Southwest
Fisheries Science Center, La Jolla Laboratory Administrative Report LJ-01-05, La Jolla, CA, 42 p.
Crone, P. R., and R. J. Conser (Editors). 2002. Reportof the eighteenth North Pacific Albacore Workshop,
La Jolla, CA, 4–11 December 2002. NMFS Southwest
Fisheries Science Center, La Jolla, CA, 92 p.

Progress

Progress has been made on the stock assessmentof several important fish stocks and in reducing
U.S. fishery impacts on protected and endangered
species. An updated blue marlin stock assessment
indicates no overutilization. The status of several
tuna stocks also has been updated. For central
western Pacific tunas, the Secretariat of the PacificCommunity annually convenes informal international scientific meetings to assemble fisheries

FAO. 2001. FAO yearbook of fishery statistics. Capture
production 1999. Food and Agriculture Organizationof the United Nations, FAO Fisheries Series Volume
88, Rome, Italy, 765 p.
Fournier, D. A., J. Hampton, and J. R. Sibert. 1998.
MULTIFAN-CL. A length-based, age-structured
model for fisheries stock assessment, with application to South Pacific albacore, Thunnus alalunga.
Canadian Journal of Fisheries and Aquatic Sciences
55:2105–2216.

24 9

6 TH ED I T I ON
OUR LIVING OCEANS

IATTC. 2001. Annual report of the Inter-American
Tropical Tuna Commission, 1999. Inter-American
Tropical Tuna Commission, Scripps Institution of
Oceanography, La Jolla, CA, 183 p.
IATTC. 2008. The fishery for tunas and billfishes in theeastern Pacific Ocean in 2007. Report of the 9th Stock
Assesment Review Meeting, Inter-American Tropical
Tuna Commission, La Jolla, CA, 49 p. Internet site—
http://www.iattc.org/PDFFiles2/SARM-9-04-Thefishery-in-2007.pdf.
Interim Scientific Committee. 2004. Report of the
Plenary Session of the Fourth Meeting of the Interim
Scientific Committee for Tuna and Tuna-like Species
in the North Pacific, February 2004, Honolulu, HI.
National Research Institute of Far Seas Fisheries, Shimizu, Japan. Internet site—http://isc.ac.affrc.go.jp/
rep/ISC4PlenaryReport.pdf.
Ito, R. Y., and W. A. Machado. 2001. Annual report of
the Hawaii-based longline fishery for 2000. NMFS
Southwest Fisheries Science Center, Honolulu Laboratory Administrative Report H-01-07, Honolulu,
HI, 61 p.

250

Kleiber, P., Y. Takeuchi, and H. Nakano. 2001. Calculation of plausible maximum sustainable yield (MSY)
for blue sharks (Prionace glauca) in the North Pacific.
NMFS Southwest Fisheries Science Center, Honolulu
Laboratory Administrative Report H-01-02, Honolulu,
HI, 10 p.
PFMC. 2003. Fishery Management Plan and Environmental Impact Statement for U.S. West Coast Fisheries
for Highly Migratory Species. Pacific Fishery Management Council, Portland, OR. Internet site—http://
www.pcouncil.org.
SCTB. 2004. Report of the 16th meeting, Standing Committee on Tuna and Billfish. Mooloolaba, Queensland,
Australia, 9–16 July 2003. Internet site—http://www.
spc.int/oceanfish/html/SCTB/index.htm.
WPRFMC. 2004. Pelagic fisheries of the western Pacificregion. 2002 annual report. Western Pacific Regional
Fishery Management Council, Honolulu, HI. Internet
site—http://www.wpcouncil.org/pelagic-data.html.