Tuna Fishery

Tuna Fishery in the Western and Central Pacific Ocean (including the Philippines) I.

Introduction

Based on Grolier International Encyclopedia (1991). tunas are among the largest and most commercially important of all fishes. Seven species, making up the genus Thunnus of the tuna and mackerel family Scombridae, are found in temperate and tropical oceans around the world and account for a major proportion of the U.S. fish catch and U.S. fish imports. The two dominant species of tuna in western and central Pacific Ocean are skipjack tuna and yellowfin tuna whose distribution and spawning areas are shown in Map 1 below. Tunas typically have cigar-shaped, streamlined bodies with two dorsal finlets—a narrow tail region, and a large, deeply forked tail. They vary extensively in size, color, and fin length. Along with the mackerel sharks, tunas are unique among fishes in having a body temperature higher than that of the surrounding water—a result of a complex circulatory system and continuous sustained activity. Fast swimmers, traveling at more than 48 km/hr (30 mph), they typically migrate long distances and appear only seasonally in any one location. Tunas occur both in surface waters and at great depths, where their large eyes help them to see in the dark. They feed on other fishes and on squid. The larget species, a highly prized sport fish, is the bluefin, Thunnus thynnus, found worldwide. Some specimens exceed 4.2 m (14 ft) and weigh more than 680 kgs (1,500 lb). Other important species include the albacore, T. alalunga, a small fish , often less than 18 kg (40 lb), which is famed for its tasty while meat, the large yellowfin, T. albacares; and the deep-water bigeye, T. obesus. The tuna fishery is controlled by international agreements limiting how much fishers may take and where they may fish—limits that not always observed. Another major problem is created by the method used to harvest tuna (as well as salon and squid): huge nets are stretched across kilometers of ocean, capturing sea birds, seals, porpoises, and dolphins and dolphin kill has been huge, constituting a threat to their populations. Map 1. Distribution and Spawning Grounds in the World Distribution and Spawning Areas of Skipjack

Distribution and Spawning areas of Yellowfin tuna

Philippines

Philippines

Geographic Distribution

Major Tuna Species of the World Table 1 shows that the top 3 tuna species: skipjack, yellowfin, and big-eye are mainly caught in the following countries: Southeast Asia (Philippines, Thailand, Indonesia), Micornesia (Samoa), Cental/South America (Mexico, Venezuela, Colombia, Ecuador), Africa (Senegal and Ivory Coast), and Europe (Spain and Italy). Table 1. Showing the Pictures of the Different Tuna Species and Certain Data

Life Cycle

3 years maximum

4 – 7 years

5 – 7 years

5 years maximum

10 – 25 years maximum

At least 12 years

1 – 2 years

Distribution of Catches of Tuna in the Western and Central Pacific Ocean It is in the western and central Pacific ocean which has the highest concentration of tuna population of the following species: yellowfin and big-eye tuna as shown in Map 2. Map 2 Distribution of yellowfin (top left), bigeye (top right), albacore (bottom left) and broadbill swordfish (bottom right) catches in the western and central Pacific Ocean [Source: Secretariat of the Pacific Community] 1

1

2

3

4

2

3

3

5

1 2

1 3

4

5

2

3

5

5 4

Ecological Importance of Western and Central Pacific Ocean (WCPO) The WCPO is characterized by the presence of islands as shown in Map 3. Map 3. Showing the island countries in the WCPO

The ecological characteristics of WCPO indicates the following: 1. The presence of several humdreds of islands which surrounded by shallow waters and coral reefs make it very rich in primary productivity and fishery productivity. 2. The vast expanse of the area with several thousand miles in length (west to east) and few thousand miles in width (north to south) makes the area ideal for a) habitat, b) shelter and b) spawning and nursery grounds for oceanic large pelagic migratory species of fish like tuna

Migration of Tuna (yellowfin and big-eye) from WCPO to Southeast Asian waters and North/South America It has been observed through research (the tagging method) that yellowfin and Big-eye tuna that are found in the WCPO migrate towards westward (Indonesia and Philippines) and eastward (North and Central America) as shown in Map 4; likewise, tuna from north and central america migrate towards the WCPO. This indicates that there is only stock of said species of tuna in the whole Pacific Ocean. Map 4. Showing the Direction of Migration of Tuna

Pacific Ocean

Long-distance (>1,000 nmi) movements of tagged Yellowfin tuna

China

Japan Taiwan

Pacific Ocean

Australia

Long-distance movements of tagged Big-eyed Tuna

But in the case of yellowfin tuna being distributed throughout the tropical and sub-tropical waters of the Pacific Ocean, there is some indication of restricted mixing between the western and eastern Pacific based on analysis of genetic samples and tagging data. Adults (larger than about 100 cm) spawn, probably opportunistically, in waters >26 C, while juvenile yellowfin are first encountered in commercial fisheries (mainly surface fisheries in the Philippines and eastern Indonesia) at several months of age. Tuna migration in the Philippines Map 5 shows the direction of migration of tuna from the Philippine waters. It has been suggested that juvenile yellowfin start to migrate out of Philippine waters at 30 cm size, and that most of these juvenile yellowfin are gone from the region by the time they reach 60 cm in length. Yellowfin larger than 110 cm are caught by hook-and-line fishers coming from the Philippines (General Santos City, Sarangani, and Davao) in the northern Celebes Sea which is part of the territorial water of Indonesia. Map 5. Indicating Migration of Tuna from Higher to Lower Latitude

Yellowfin tuna migrate out of the Philippine waters at 30 cm in fork length ( 6 months old)

Direction of migration is towards the warmer water of the equatorial o 15 temperature region as Autumn approaches But there are large tuna that are (Nov-December-January) or caught in the Pacific side outside When tuna reaches 30 cm or of Municipal water but within the EEZ 6 months old from spawning Time (summer/early spring)

10o

Northern Celebes Sea where yellowfin tuna 1.1 meter long (fork length) are caugh by hook& line fishers

5o

0o

Most of this surface tuna catch is made by fleets of large purse-seiners in the equatorial band (5oN-5oS).

5o

Map 6 below shows the frequented fishing grounds for tuna being located near the equator within the latitude 5o North and 5o South of the Equator, although tuna can be caught at higher latitudes

during certain months of the year particularly during summer/spring months when temperature is relatively warmer. Map 6. Showing Tuna Concentration near the Equator

California

Pacific Ocean 5 -5

Austrialia

Fishing Grounds of Tuna as indicated by dots

Food Requirement of Tuna Based on the Food Web as illustrated below, tuna primary food are herrings, sardines, anchovy, and squids. Certain species tend to become cannibalistic. Figure 1. Food Web in Tropical Regions FOOD WEB OF THE TROPICAL SEA

Large Sharks

Marlin

Medium-sized Sharks

Top predators Tuna/

Predators Mesopelagic Fishes (200m-1km depth)

Lancetfish (e.g. swordfish)

Snake Mackerel

Filterers Vertically-migrating Mesopelagic fishes

Herbivores

Algae

Sardines Sardines Flying fish Flying fish Herring anchovy

Euphausiids (zooplanktons)

squid

Hyperiid Amphipods (small crustaceans)

Dolphin

Lantern fish

Shrimps

Copepods Copepods/ (zooplanktons diatoms

Coccolithopores (phytoplanktons)

Dinoflagellates (phytoplanktons)

Ocean sunfish

The reason for the fact that most species of tuna particularly skipjack and yellowfin are usually caught in the latitude 5o North and 5o South is that, it is in this area where primary production and small pelagic fish production (as the main food of tuna) are highest as compared with those of the higher latitudes. II.

Status of Tuna Fishery

A.

Biomass and Recruitment

1. Initially, most of the biomass is estimated to have occurred in the tropical regions 2 and 3. Recently, biomass has increased in both the northern (region 1) and southern (region 5) regions. 2. Overall, biomass increased strongly in the late 1970s and 1980s driven by the increased recruitment, but has been in decline since the mid-1990s. The recent decline has been particularly marked in regions 2 and 3. Despite these recent declines, current total biomass is estimated to be at similar levels to the 1960s and 1970s. 3. Figure 2 presents the following: Region 1 highest recruit comes from Region 2 at 50%, followed by Region 1 itself at 32%; Region 2 highest recruit comes from Region 2 itself at 74%, followed by Region 3 at 18%; Region 3 highest recruit comes from Region 3 itself at 58%, followed by Region 2 at 25%; Region 4 highest recruit comes from Region 2 at 43%, followed by Region 4 itself at 27%; Region 5 highest recruit comes from Region 5 itself at 80%, followed by Region 2 at 12%; Regions 2,3, and 5 with highest recruits coming primarily from within are also receiving certan levels of recruits. Figure 2. Showing Tuna Recruits from Different Regions 5 3

5

3

5

5 4

2

3 3

5

3

2 2 1

3

21 1

1

2

1

B.

Fishing Pressure (Tuna Production)

1.

Tuna Production (Worldwide)

Total annual world tuna production in the year 2000s is 3.159 million metric tons. Catch of skipjack tuna, yellowfin tuna, and big-eye tuna represent 50-55%, 35%, and 8% of the total tuna catch, respectively.

a. The western and central Pacific Ocean (WCPO) currently supports the largest industrial tuna fishery in the world, with total annual catches from 1991 to 1994 of approximately 1,000,000 mt. The three gear types accounting for most of the catch in the area are longline, purse seine and pole-and-line. Large-mesh drift-net, handline and trolling gear have been utilised in some areas, but not to the extent of the above-mentioned gear types. The primary target species are skipjack, yellowfin, bigeye and albacore. Skipjack is the most important of the four major tuna species in the fishery, accounting for 67 per cent of the catch by weight in 1992, followed by yellowfin (24.5%), bigeye (5%) and albacore (3%). Purse seine gear was responsible for 80 per cent of the total catch, with pole-and-line gear accounting for 7 per cent, longline gear 12 per cent and troll gear 1 per cent. b. Nearly 70% or 2 million ton of the world’s annual tuna harvest, currently (2000s) 3.2 million tons, comes from the Pacific Ocean c. Skipjack tuna (Katsuwonus pelamis) dominate the catch. Although skipjack are distributed in the surface mixed layer throughout the equatorial and subtropical Pacific, catches are highest in the western equatorial Pacific warm pool, a region characterized by low primary productivity rates that has the warmest surface waters of the world’s oceans. 2.

Tuna Production (Philippines)

a. In the Philippines, the 2000 catch of big-eye tuna and yellowfin ccategorized as “tambakol” catch) skipjack, and bonito was 243,000 m.t. or 7.7% of world production (see Graph 1 below). Graph 1. Philippine Marine Fish Catch (BAS Fisheries Statistics 2000)

Skipjack - 113,000 m.t. Yellowfin/Big-eye - 90,000 Oceanic Bonito - 40,000 m.t 243,000 m.t.

1,316.60

Alumahan

Pusit

Oceanic Bonito

Alimasag

Bisugo

Species Katchorita

Comparison of Tuna Production (Philippines, Indonesia, and Malaysia)

Philippines

Matangbaka

Frigate tuna Big-eye and Yellowfin tuna

Total (15 species)

29.5 26.8

Total for Tuna

36.3

Hasahasa

40

Sapsap

53.7 46.8

Dilis

71.4 67.3

Tunsoy

90.3 79.6

Tulingan

113 112.2 92.9

Tambakol

355.5 200.5

Skipjack tuna

3.

1,740.30

Gulyasan

256

Tamban

2000 1800 1600 1400 1200 1000 800 600 400 200 0

Galunggong

Catch (x000 m.t.)

Philippine Marine Fish Catch

a. Durng the period 1981-1991, top tuna producers among the ASEAN countries were the Philippines and Indoneisa (see Graph 2 below). It is estimated that Indonesia (also facing the Pacific ocean) which is closer to the tuna-rich equatorial region and the fact that yellowfin tuna and big-eye are considered already overfished in the western and central Pacific Ocean has surpassed now the Philippines in tuna production. b. Malaysia, the Philippines, Indonesia, and Thailand use purse seine, longline and vertical handlines to fish for tunas in the region; the same oceanic and neritic tuna species are also taken. c. In the Philippines the marked increase in growth of the tuna fishery has been attributed to the use of FADs (called payaos in the Philippines). Yellowfin tuna, skipjack, and frigate tuna (Auxis thazard) are the principal species caught in the Philippines. Purse seines, ring nets, and handlines catch juvenile yellowfin ranging in size from 16 cm to 55 cm. Since few yellowfin between 60 cm to 200 cm are caught by the Philippine tuna fishery, it has been suggested that juvenile yellowfin start to migrate out of Philippine waters at 30 cm size, and that most of these juvenile yellowfin are gone from the region by the time they reach 60 cm in length. Yellowfin larger than 110 cm are caught by hook-and-line fishermen in the northern Celebes Sea. Catches reported by the national authorities in Indonesia have been used in this assessment, but further validation is required. Increased purse seine catches using FAD sets in region 3 have also contributed to the increase. Graph 2. Comparison of Tuna Production among 4 ASEAN countries 450 400

Skipjack Yellowfin Big-eye/Yellowfin Skipjack Frigate Tuna Frigate Tuna Big-eye Bonito Tuna

Indonesia tuna catch increasing Philippines

Philippines

Philippines

Indonesia

Thailand Malaysia

Long-tail Frigate tuna Yellowfin

92

93

94

95

96

97

98

99

d. In Indonesia the yellowfin tuna and skipjack are the dominant species in the catch. The use of FADs (called rumpons in Indonesia) also play an important role in the development of the Indonesian tuna fishery. Presently tuna are caught by a variety of gears including purse seines, handlines, troll lines, and longlines.

2000

01

C.

Catch by gears - WCPO

1. Since 1990, the yellowfin tuna catch in the western and central pacific oecean (WCPO) has varied between 320,000 m.t. (1990) and 485,000 m.t. (1998) as shown in Graph 3 but starting 1998 total volume of catch had decreased

Metric Tons

Graph 3. Showing the WCPO Yellowfin Catch by Gears

2. Yellowfin tuna are harvested with a diverse variety of gear types, from small-scale artisanal fisheries in Pacific Island and southeast Asian waters to large, distant-water longliners and purse seiners that operate widely in equatorial and tropical waters. Purse seiners catch a wide size range of yellowfin tuna, whereas the longline fishery takes mostly adult fish 3. Purse seiners harvest the majority of the yellowfin tuna catch (49% by weight in 1996– 2000), with the longline and pole-and-line fisheries comprising 15% and 3% of the total catch, respectively. Yellowfin tuna are often directly targeted by purse seiners, especially as unassociated schools. 4. Longline catches in recent years (56,000–73,000 t) are well below catches in the late 1970s to early 1980s (which peaked at 117,000 t), presumably related to changes in targeting practices by some of the larger fleets. 5. Catches in the ‘Other’ category are largely composed of yellowfin tuna from the Philippines and eastern Indonesia. These catches come from a variety of gear types (e.g. ring net, gillnet, handline and seine net) and have increased steadily over the past decade. Based on catch data provided by those countries, recent catches represent approximately 35% of total WCPO yellowfin tuna catches.

Catch by Gears – Philippines (Northern Samar) 1. Map 7 shows that beyond the 15-km limit municipal water in all municipalities, there is large area for tuna fishing. Yellowfin tuna and skipjack (gulyasan or budlis) are caught through “payao” fishing using hook & line outside of the 15-km limit. It has been reported that the size of tuna caught in said area is much more smaller than those caught in the offshore of Gamay by commercial fishing boats coming from as far as General Santos City.

Map 7 Northern Samar indicating the tuna fishing ground

100 50

Pating Dolphin Sibubog Budlis Yellowfin lamadang San Bernardino Strait

Smallerr Yello wfin Tuna towards shallow water of San Bernardo Strait

Bugko Payao Drifted by strong current/waves last July 2004 PAYAO

payao

Bugko

25 kms from shore

m 15 k

1000 fathoms

ici mu n

at pal w

NOV-APR

rato ry P a

PAYAO Other Group

PAYAO Other group

payao

M AMIHANig

it fro er l im

s land m is

0

5

10

coral m rom sand limit f m

Biri Island rel ine sho from mainland 15 km distance

Camongon Island

Rosario Rosario

Jose SanSanJose

Bobon

Catarman

Catarman

Laoang Bay

rock sand

Dona Lucia

10 0f

Kahayagan Island

limit

Chitongco

and

ath om

s kip

jac k )

s

15 kms

rocky

20 fathoms

wf in

Batag Island

50 fathoms (90 meters) Cauhagan Island mud

m sand 8 -k

na ( ye llo

2,500 has

mud

15-k

coral

f Tu

1 00 0f

100 fathoms

nd ain la

th o

Big t o w g er Y o f t ard s d e llo w h e P eep f in acif er w Tun ic o ate a ce a r n

s

Laoang Pambuhan

Bugko San Roque

Mondragon

m

Laoang Island

Bantayan Bay

25 km s

ath o

Palapag Laoang

Catubig River

Mondragon To Catubig

Northern

S a m a r

Gamay

2. The catch of tuna is all-year round, but the peak season is during the period of “habagat” that covers the months of May to October. Graph 4 shows that Frigate Tuna or “tulingan” was caught in big quantity in August by Dona Lucia fishers but within the nearshore water, while Budlis and yellowfin were the main catch by Chitongco fishers in May (Graph 5) and by Bugko fishers in April and May (Graph 6) all in the fishing grounds beyond the 15-km limit. Graph 4. Showing the Hook & Line Catch of Brgy Dona Lucia

Graph 5. Showing Fisch Catch of Brgy Chitongco Fishers using Hook % Line

Graph 6. Showing Fish Catch of Brgy Bugko Fishers Using Diff. Gears

During the months June to August N. Samar was frequented by typhoons and bad weather when deepsea “payao” fishing could not be possible, hence fishers confined their fishing activities within the nearshore water.

D.

Effect of fishing to total biomass

1. The greatest impacts of tuna fishing have occurred in regions 2 and 3, where the “actual” BIOMASS has DECREASED between the period 1962-1998/2000) as shown in the Graph 7. This result would suggest that there has been a significant DEPLETION OF SUBPOPULATIONS in these regions, primarily by the domestic fisheries of the Philippines and Indonesia and the combined purse seine fishery. But the BIOMASS (or sometimes called the standing stock biomass) is computed based on several data subjected to computer program which only experts can be able to do.

Graph 7. Showing the Decreasing Biomass of Yellowfin Tuna and Exploitable Abundance versus Actual Catch Per Unit Effort (CPUE)

Exploitable abundance is Higher than the CPUE Between 1980-2000

Exploitable abundance is lower than the CPUE Between 1990-2000

Exploitable abundance is lower than the CPUE Between 1990-2000

Exploitable abundance is lower than the CPUE Between 1990-2000

Exploitable abundance is Higher than the CPUE Between 1990-2000

2. Graph also shows that there was too much fishing mortality or higher fishing pressure directed at the juveniles than that of adult yellowfin tuna. 3. Aside from biomass level, an indicator of overfishing can also be gleaned from the comparative data between the actual catch per unit of fishing effort (CPUE) and the Exploitable

Abundance of tuna in each region as shown in above Graph 7 which show that it is in Regions 2 and 3 and to a certain extent Region 4 where the actual CPUE is more than the Exploitable abundance. Therefore, Graph 7 (on biomass change) is validated by the Graph 7 (on CPUE vs. Exploitable Abundance). E.

Effect of Fishing on the Size of Fish Population (Length-Frequency)

1. The Graph 8 below shows the length-frequency of the catch by the different fishing gears. Longline used in the 5 Regions have yellowfin tuna catch of larger size; catch of purseseines in Regions 2 and 3 using fish aggregating devices (FADs) and Logs consist mostly of smaller size groups; the catch in the Philippines using ring net and handline and Indonesia both countries being part of Region 2 consists of smaller size group; and Ring net used in the

Philippines has catch of yellowfin tuna of the smallest size group. Graph 8. Showing the length-frequency of yellowfin of the different fishing gears in different Regions of WCPO.

45 cm (fork length) catch of yellowfin in Northern Samar (May-Aug) in “payao” area

0.5 of maximum size of yellowfin

2. There is a pattern that yellowfin tuna and other species are found in the Philippines and Indonesian waters during the early years of their life cycle and then migrate towards deeper waters as they grow in size. Length-weight-age relationship 1. The Length-frequency data are used to determine the status of the fishery species. The information needed are the relative size or the ratio of the average size of fish caught and the attainable maximum size of the fish. Based on the available data on yellowfin tuna, the Graph 9 below is constructed. Graph 9. Showing the Weight-Length-Age Relationship Growth Rate of Yellowfin Tuna 115-150cm or 130cm ave.

200 Individual Weight (kgs)

180 160 140 120 100

1.9-2.1 meters (fork length); max 7 years = 176 kgs 2.1 meters

At 30 cm fork length (1 kg) Yellowfin tuna Starts to move out of Philippine waters; a significant number larger than 30 cm are still caught within Philippine waters

120-165mc or 140cm ave.

Maturity age 120 cm fork length = 2 - 3 yrs

47-67 or 60 cm ave.

80

176 176 176 176

90-125cm or 110 cm ave.

63.5 kgs= 4 years

18 cm (Fork length)

20 kgs = = 20 kgs (2.5 years) 2.5 yrs

60

63.5kgs

3.4 Kgs= (1.5 years)

40 20 0

3.4

0

1 0

2 0.5

3 1.0

4 1.5

5 2.0

6 2.5

7 3.0

8 3.5

9 4.0

10 4.5

11 5.0

12 5.6 13 6.0

Age (years)

Graph 10. Showing the Attainable Max.Size and half-max size of Yellowfin tuna Length-Weight Relationship of Yellowfin Tuna Fork Fork length Length Max.= 180cm Max.=190 cm or 176 kgs

200 180 160 Weight (kgs)

140 120 100

Fork length ½ max.=95cm or 20 kgs

80 60 40 20 0 0

10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200

Fork Length (cm)

14 15 6.5 7.0

2. Based on Graph 10 above, the half-maximum size of yellowfin is 96 cm or 20 kgs. Average of size of yellowfin catch below this size (length and weight) is considered overfished. 3. Based on the preceeding item no. 2, the status of yellowfin may be characterized as follows: a. It is in Regions 2 and 3 where the length-frequency has modal point value less than half the maximum size of the fishery species. If the maximum of yellowfin tuna is 1.9 meters, its half value is 95 cm (or 20 kgs) which is just 0.5 the maximum length which means that the specie is at the boundary between overfished and high-yielding status. Graph above shows that yellowfin tuna is already overfished in regions 2 and 3 and the fishing gears that contributed to their conditions are purse-seines and ring nets with fish aggregating device. The use of long line in Regions 1, 2. 3, 4, 5 resulted to the catching of large size yellowfin which is more than 0.5 of the maximum observed length. This means that longline is a more sustainable gear. b. In the case of Northern Samar, Philippines which is part of Region 2, Graph 11 shows that the size of yellowfin ranges from 30 cms to 45 cms which is less than half the maximum sizes of the specie indicating that yellowfin is being overfished. But it has been yellowfin caught in the offshore water of Gamay are of the big size which is more than half the maximum size of the specie. On the other hand, skipjact tuna or “budlis” catch has average size of 40 cm (standard length) or 42.5 cm (fork length) whish is more than half the usual maximum size (80 cm) showing that this specie is still high-yielding in the Philipiine waters. c. But considering the western and central Pacific Ocean as a whole, it is only in the Philippine and Indonesian water that undersize yellowfin and big-eye tunas are caught. The main reason is that these species stay in the Philippine-Indonesian water in the early stage of their life cycle and migrate towards the deeper and warmer waters as they grow in size.

Graph 11. Catch data on yellowfin and budlis caugh by fishers of Brgy Chitongco

Payao Catch data on Yellowfin by Chitongco Fishers per day (April-June) Individual weight (kg) Standard length (cm)

50 45

Invidividual weight and standard length (cm)

45

43

45

45

45 39

38

40

45 39

35

Yellowfin becomes Sexually Mature at 120 cm (FL) or 2-3 Yrs of age; others mature at 50-60 cm or 1-1.25 yrs.old)

30 30 25 20 15 10 5

2.5

2.25

2

2.25

2.5

1.5

2.5

2

1.25

2.5

0 April

August

Month (2004)

Payao Catch data on Budlis per day per fisher (April-June) individual weight (kg) Standard length (cm)

50

45

43

45

38

Weight (kg) and Standard length (cm)

40

41

40

40

40

Skipjack between 41-87cm (FL) can disperse between 80,000 and 2,000,000 eggs per season

35 30 30 25 20

.

15 10 5

2

1.5

1.25

1.9

0.75

0.9

3

0 April

August Months

1.5

Weight Frequency 1. Weight-frequency is similar to length-frequency. Instead of length, the weight data are used to determine the change over time or comparing the weight composition of a given specie caught in different Regions or catch of said specie by different gears in the same Region. Graph 12. Showing that Longline weight-frequency catch

Half-maximum length rf 95 cm or 20 kgs

2. The correctness of the constructed length-weight data of yellowfin is confirmed by the weight-frequency of the yellowfin caught by longline as presented in Graph 13 below. The halfmaximum length as shown in the length-frequency graph which is located to the left of the distribution curve as in the case of longline is also the same point in the distribution curve of the weight-frequency curve. This means that both the length-frequency and weight frequency can be used in determining the status of the fishery. Longline fishing does not contribute to overfishing. Graph 13. Showing the Longline weight-frequency catch during 1997-2001

1 year

Half-maximum Size of yellow fin

1 year

1 year

1 year

3. The above Graph indicates that since 1997 until 2001, longline fishing has been consistent to be contributing to sustainable fishing.

Tuna Producing Area and Tuna Fishing Operation Map 8 shows that the Philippines and Indonesia are near the equatorial region and facing the tuna-rich WCPO. For being so, the said countries have the highest tuna production among ASEAN countries. 1.

Map 8. Showing the Major Tuna Producing Countries in Asia and Tuna Fishing Grounds

Major Tuna Producing Countries in Asia: Philippines Indonesia Thailand Malaysia

THAILAND

PHILIPPINES

an sslarge iw ng a e i T h d s yL f an e Fi vel n o , i o s a re larg lat lati cie o e K h R pu pe th wit u Po na s So tuna , tu n pa hing a J tc ing Ca et h e is , Fl

MALAYSIA INDONESIA

ich line r a g un ( lon ine) T e e rg ound se-s a L Gr ur p

General Santos/Davao Transhipment Place for Tuna caught in the Pacific Region

The following Table 2 presents 2002 tuna fish catch in the western and central Pacific Ocean (WCPO), by fishing gears, by what nationality, and the status of tuna species:

Table 2. Showing WCPO tuna fishery data Species

Fishing Gears Purse-seine Catch (m.t.)

%

Pole & Line Catch (m.t.)

%

Longline Catch (m.t.)

%

Troll gears Catch (m.t.)

Sipjack66%

962,233

83

281,322

85

-

-

-

Yellowfin22%

176,175

15

16,548

5

82,252

34

-

Big-eye6%

21,696

2

3,309

1

82,252

34

-

Albacore Tuna – 6%

-

TOTAL

1,160,104

REMARK

Catches for the Korean and Taiwanese fleet increased in 2002 while Japan catch decreased

29,787

58

330,968 Atlantic tuna is caught by Japanese coastal and offshore fleet

77,412

17

241,917 Caught by large vessel and distant water fleet of Japan, Korea, and Taiwan

-

11

Status 2002 level of stocks are high and catch levels are easily sustainable 2002 not being overfished and current level of exploitation is sustainable; any future increases in fishing mortality would not result in any longterm increase in yield and may move the yellowfin stock to an overfished state Stocks not in an overfished state although overfishing is occurring and the current level of exploitation appears not to be sustainable in the long term, unless the high recent recruitment is maintained in the future. The impact of the fishery on the overall stock is estimated to be small, and higher levels of catch could likely be sustained.

4,477 also other variety of artisanal gears mostly in eastern and southern Philippines; lower effort of USA fleet

2. Skipjack tuna (Katsuwonus pelamis) contributes 66% in total tuna catch in the WCPO (see Table 2), 70% of the total tuna catch in the Pacific Ocean, and 50-55% of the world tuna catch, but the largest catches are taken from the warm-pool in the western equatorial Pacific. U.S. purse-seine fishing vessels catch skipjack tuna and based on the analysis of catch and effort data, it was found out that one of the most successful fishing grounds is located in the vicinity of a convergence zone between the warm (>28-29° C) low-salinity water of the warm-pool and the cold saline water of equatorial upwelling in the central Pacific 3. Yellowfin tuna constributes 22% of total tuna catch in WCPO, 35% of the total world tuna catch and is being harvested by smalls-cale artisanal fisheries in Pacific Island and southeast Asian waters to large, distant-water longliners and purse seiners that operate widely in equatorial and tropical waters. Purse seiners catch a wide size range of yellowfin tuna, whereas the longline fishery takes mostly adult fish. 4. Bigeye tuna (Thunnus obesus) contributes 6% of the total tuna catch in WCPO and is considered an important component of tuna fisheries throughout the Pacific Ocean. They are the principal target species of the large ‘distant-water’ longliners from Japan and Korea and of the smaller ‘fresh sashimi’ longliners based in several Pacific Island countries. Bigeye tuna are fundamental to the economic survival of the longline fishery in the western and central Pacific Ocean.

5. Purse-seine tuna catch in the WCPO is the highest at 58%, followed by pole % line at 17%, longline at 11%, and troll line with other artisanal gears mostly in eastern Indonesia and the Philippines at 14%. A typical high-tech purse-seine fishing vessel is shown in Figure 3. 6.

The western and central Pacific Ocean (WCPO) currently supports the largest industrial tuna fishery in the world The three gear types accounting for most of the catch in the area are

longline, purse seine and pole-and-line. Large-mesh drift-net, handline and trolling gear have been utilised in some areas, but not to the extent of the above-mentioned gear types. The primary target species are skipjack, yellowfin, bigeye and albacore. 7. The foreign tuna fishing vessel operators have been doing transshipment of their tuna catch at General Santos City or Davao City so that they can economize in their cost of operation and continue fishing operation. However, in the process certain volume of tuna with lower quality (particularly caught by purse-seine and ring net) are marketed in the country at lower price than those large tuna caught by small Filipino fishers in the tuna-rich northern Celebes Sea using handline. This results to the lowering of the market price of tuna caught by the handline fishers. Therefore, the good quality tuna are marketed abroad possibly through Japanese/Korean outlets at lower price ensuring them high profit. Figure 3. Typical Purse-seine fishing vessel and purse-seine operation Purse-seine Hauling of seine net (mechanized boom)

Surface line floaters

Boom

Service boat used in tugging the other end of the net while Mother boat moves in circular manner as to encircle the school of fish

Radar

Trapped fish Bottom line with sinkers enclosed forming purse

Conclusions 1. There is the harvesting of the same tuna stock(s) by countries fishing in the same region. Using the most efficient fishing gear (Filipino-owned or joint venture with Japanese, Taiwanese, Koreans, and U.S.), each country harvests the tuna at a particular size and at a particular point in the migration route. Thus, the harvest of tuna by one country impacts the present and future catches of the same stock(s) of tuna by countries which harvest these resources later on in the migratory route of the tuna. 2. Based on item no. 1, there is an urgent need to study interactions among fisheries nationally and regionally. Without a coordinated and directed approach to gather, document,

analyse, and interpret the relevant data, the tuna fishery resources in the southeast Asia region cannot be assessed and managed effectively to ensure sustained harvests. 3. Fishing mortality for juvenile yellowfin tuna has increased strongly since about 1992, partly as a result of catchability increases in the purse seine fisheries. But a significant component of the increase is attributable to the Philippines and Indonesian fisheries, which have the weakest catch, effort and size data. This is of continuing concern. There has been recent progress made in the acquisition of a large amount of historical length frequency data from the Philippines and regular sampling operations are now in place there. However, uncertainty with the total catch and size composition data for the Indonesian fishery continues to be a problem. 4. The overall impact of fishing on stock biomass is estimated to be in the vicinity of 35% in recent years. The impact is differentially high in the tropical regions (around 50%) compared to the subtropical regions. This means that the tropical regions which are the most productive in fishery are also the most exploited fishing grounds. However, the level of yellowfin biomass in the MCPO areas is not yet in the critical condition (or being overfished or in an overfished side). 5. The Philippine waters and Indonesian waters have the most productive tuna fishery among the ASEAN countries being both facing the WCPO areas found to be thickly populated with yellowfin tuna and big-eye tuna. However majority of the tuna biomass in said countries are composed of juveniles indicating that this part of the WCPO serves as the tuna habitat in their 1 st few months of their life cycle. And it is towards the winter months that yellow fin and big-eye tuna (about 30 cm in fork length) migrate out of the Philippine waters towards the equatorial region at less than 5o latitude. However, large size tuna can be caught in large quantities off Samar island outside of the municipal water. 6. Based on item no. 5 above and the fact that tuna fishery (yellow fin and big-eye) in the WCPO areas are still not considered overfished particularly the skipjack tuna, the smallscale and artisanal fishers should be provided with incentives to engage in tuna fishing through the use of FAD using handlines or ring net for periodic total harvest.

7. The transshipment scheme of foreign tuna fishing vessel operators to dump tuna catch of poorer quality being caught by purse-seines in the southern Philippines’ fish landing areas (General Santos City – tuna cannery in the Philippines) for the purpose of lowering down the price of qood quality tuna caught by the Filipino tuna handliners must be exposed and opposed.

REFERENCE CITED BAS Fisheries Statistics Chee, P.E. Tuna fisheries interactions in Malaysia. Fisheries Research Institute, Dept of Fisheries Malaysia, 11700 Gelugor, Penang Malaysia. Grolier International Enclopedia. 1991 Hampton, J, Langley, A., Williams, P. The Western and Central Tuna Fishery 2002. Hampton, John. Stock assessment of yellowfin tuna in the western and central Pacific Ocean. SCTB15 Working Paper, Oceanic Fisheries Programme, Secretariat of the Pacific Community; Noumea, New Caledonia Hampton J., Bigelow, K., Labelle, M. A summary of current information on the biology, fisheries and stock assessment of bigeye tuna (Thunnus obesus) in the Pacific ocean, with recommendations for data requirements and future research. Oceanic Fisheries Programme, Secretariat of the Pacific Community (SPC). Lehodey P., Andre J-M, Bertignac M., Hampton J., Stoens A., Menkes C., Memery L., Grima N. Predicting skipjack tuna forage distributions in the equatorial Pacific using a coupled dynamical bio-geochemical model. Oceanic Fisheries Programme, Secretariat of the Pacific Community (SPC).

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