THE WESTERN AND CENTRAL PACIFIC TUNA FISHERY OVERVIEW OF THE

Document Sample
THE WESTERN AND CENTRAL PACIFIC TUNA FISHERY  OVERVIEW OF THE Powered By Docstoc
					ATC17/INFO.E SOUTH PACIFIC FORUM FISHERIES AGENCY

SEVENTEENTH ANNUAL CONSULTATION
MULTILATERAL TREATY ON FISHERIES BETWEEN THE GOVERNMENTS OF CERTAIN PACIFIC ISLAND STATES AND THE GOVERNMENT OF THE UNITED STATES OF AMERICA

INTERNAL MEETING OF THE PACIFIC ISLAND PARTIES
(17–18 March 2005, Nuku’alofa,Tonga)

A PRELIMINARY REVIEW OF THE WESTERN AND CENTRAL PACIFIC OCEAN PURSE SEINE FISHERY 2004 AND OBSERVER AND PORT SAMPLING DATA 2003–2004
Summary There are two papers provided by the OFP of the Secretariat for the Pacific Community (SPC). The first paper provides a preliminary review of the Western and Central Pacific Ocean purse seine fishery in 2004. This review is a preliminary description of activities by major purse seine fleets in the Western and Central Pacific Ocean (WCPO) during 2004. Where relevant, comparisons with previous years' activities have been included, although it should be noted that data for 2004 are not complete. The second paper provides a description of the observer and port sampling data for the period 2003-2004 under the Multilateral Treaty on Fisheries with the United States. These data were provided to the Oceanic Fisheries Programme (OFP) of the Secretariat for the Pacific Community (SPC) for research purposes. Port sampling data are collected from US purse seine vessels at points of unloading (almost exclusively in Pago Pago) by the US National Marine Fisheries Service (NMFS) and provided, through the Forum Fisheries Agency (FFA), to the OFP every two months. Observer data are collected through the Treaty Observer programme managed by FFA and provided to the OFP on a semi-annual basis. Recommendation The Pacific Island Parties are asked to note the issues discussed in the two papers.

0

ATC17/INFO.E

PRELIMINARY REVIEW OF THE WESTERN AND CENTRAL PACIFIC OCEAN PURSE SEINE FISHERY 2004

A paper prepared for the Internal Meeting of Pacific Island Parties to the South Pacific Regional US Multilateral Treaty March 17–18, Nuku‟alofa, Tonga

Oceanic Fisheries Programme Secretariat of the Pacific Community

March 2005

1

ATC17/INFO.E

1

Introduction

1. This review is a preliminary description of activities by major purse seine fleets in the western and central Pacific Ocean (WCPO) during 2004 (Figure 1). Where relevant, comparisons with previous years' activities have been included, although it should be noted that data for 2004 are not complete.
40 N

Western and Central Pacific Ocean

20 N

0

20 S

40 S

Eastern Pacific Ocean
120E 140E 160E 180 160W 140W 120W 100W 80W

Figure 1. The western and central Pacific Ocean and the eastern Pacific Ocean.

2
2.1

Purse seine tuna fishery
Historical Overview

2. The purse-seine fishery has accounted for around 55–60% of the WCPO total catch since the early 1990s, with annual catches in the range 790,000–1,200,000 mt (Figure 2). The majority of the WCPO purse-seine catch is taken by the four main distant-water fishing fleets (Japan, Korea, Taiwan and USA), which currently number around 140 vessels, although there has been an increasing contribution from the growing number of Pacific Island domestic vessels in recent years (48 vessels in 2003), with the balance from Philippines fisheries and a variety of other fleets.

1,200,000 1,000,000

YELLOWFIN SKIPJACK BIGEYE

Catch (mt)

800,000 600,000 400,000 200,000 0
1972 1974 1976 1978 1980 1982 1984 1986 1988 1990 1992 1994 1996 1998 2000 2002

Figure 2. Purse-seine catch of skipjack, yellowfin and bigeye tuna in the WCPO.

1

ATC17/INFO.E

2.2

Preliminary Catch Estimates and effort (2004)

3. The 2003 purse-seine catch of 1,195,021 mt (for all fleets) was the second highest on record and maintained the catch in excess of 1,000,000 mt since the record year attained in 1998. Table 1 compares 2003 catch estimates with the preliminary 2004 purse-seine catch estimates for the five main purse-seine fleets operating in the WCPO (Japan, Korea, PNG, Taiwan and the USA), and Figure 3 shows the trends in annual purse seine catch by the major fleets since 1996. 4. The preliminary 2004 catch estimates by fleet show that the Taiwanese and PNG fleet increased their catches compared to 2003, while the Korean and US fleet catches dropped. More information on the reasons for these trends will no doubt be forthcoming once fleet numbers and catches have been confirmed for 2004. 5. While the 2004 logsheet data for the other Pacific-Islands purse seine fleets are incomplete, and estimates are not yet available, it is expected that total catches will be at least the same level as 2003, based on vessel activity during the year. As in other years, the distant-water Philippine fleet, which operates almost exclusively in PNG waters, is likely to have accounted for around 20,000–30,000 t. during 2004. The recently-established New Zealand and Chinese purse seine fleets continued to expand their activities during 2004 with catches from these fleets likely to be higher than what was taken in 2003, which was around 21,000 t. and 23,661 t, respectively (Lawson, 2004 – the NZ fleet total includes some domestic fishery catch). There has been no indication of activity by the Spanish fleet in the WCPO in recent years. 6. Trends in monthly cumulative catches for the major fleets over the past three years (based on logsheet data received and processed to date1) also offer some insight into level of total catch for 2004 (Figure 4). 7. Skipjack catches for the major fleets in 2004 were at a similar level for corresponding months in 2002 and 2003. Since the skipjack catch in the latter months of 2004 is already at the level of 2003 for the same period (with more logsheet data to be received for the latter months of 2004), it is clear that the total skipjack catch for 2004 will be higher than in 2003, and possibly approaching the level of 2002 (which was the record year for skipjack catch). 8. In contrast, the Yellowfin catch during 2004 was poor and with most of the data already processed, only accounts for 12% of the total catch. This proportion is in contrast to around 22%, which is the average proportion of yellowfin in the total catch over the past seven years. Based on current trends for 2004, the yellowfin catch will be around 80% (at best) of that reported in recent years. 9. Based on the logsheet data currently available, and despite a poor yellowfin catch, it is expected that total catches in the purse seine fishery for all fleets will once again exceed 1,000,000 mt in 2004. Table 1. Estimated purse seine catches (metric tonnes) for 2003 and 2004 (preliminary) for the five main purse seine fleets operating in the tropical WCPO.
Vessel Nation Japan Korea PNG Taiwan USA TOTALS 2003 Purse-seine catch estimates (Lawson, 2004) 156,8962 190,452 157,860 201,3175 87,897 794,422 Preliminary 2004 Purse-seine catch estimates 160,0003 155,0003 175,930
4

Preliminary 2004 purse seine catch (based on logsheets) 146,680 126,750 138,728 213,267 50,894 676,319

% Coverage : logsheets to preliminary estimates (2004) 91.7 % 81.8 % 78.8% 87.0 % 75.5 % 84.2%

245,0003 67,4446 803,374

1

this represents the fishing months where most of the logsheet data for these fleets have been received and processed, which in this case is the period up to and including the first 7–8 months of 2004; Japanese purse seine data are not included since coverage of logsheet data for 2004 is currently less than 50%. 2 2003 Japanese estimate are for the tropical WCPO fishery only; the 2003 WCPO Japanese catch estimate (including the area north of 25°N) was 210,967 t.; logsheets provided to SPC by member countries cover EEZ activities only 3 Preliminary estimates determined from coverage according to monthly vessel activity. The preliminary 2004 Korean purse seine catch estimate does not take into account the catches of two vessels that fished in 2003, but have yet to submit logsheets for 2004. 4 The preliminary estimate of the PNG purse seine catch for 2004 was determined from coverage according to monthly vessel activity. 5 Taiwanese official estimates do not include catches (around 30,000 mt) from several Taiwanese vessels operating under Taiwanese bilateral arrangements with Pacific Island member countries, but have been registered in Vanuatu 6 Preliminary estimated of 2004 catches was provided by Bob Skillman (NMFS) on 4th March 2005. Total estimated catch – 67,444 mt (46,342 mt SKJ, 16,485 mt YFT, 4,617 mt BET).

2

ATC17/INFO.E
300,000 250,000
Total Catch (mt)

Japan Korea PNG Taiw an USA

200,000 150,000 100,000 50,000 0 1996 1997 1998 1999 2000 2001 2002 2003 2004

Figure 3. Trends in annual catches for the top five purse seine fleets operating in the tropical WCPO, 1996–2004. (2004 data are provisional)

800,000 700,000
Metric tonnes

SKJ - 2002 SKJ - 2003 SKJ - 2004

600,000 500,000 400,000 300,000 200,000 100,000 0 1 2 3 4 5 6 7 Month 8 9 10 11 12

160,000 140,000
Metric tonnes

YFT - 2002 YFT - 2003 YFT - 2004

120,000 100,000 80,000 60,000 40,000 20,000 0 1 2 3 4 5 6 7 Month 8 9 10 11 12

Figure 4. Cumulative skipjack (top) and yellowfin (bottom) purse-seine catch for 2002, 2003 and 2004 (provisional), based on logbook data (catches are for the Japan, Korea, PNG, Taiwanese and US fleets) 10. Figure 5 shows the annual trends in the set types by each fleet. The proportion of sets on free-swimming (unassociated) schools of tuna dropped for all fleets in 2004 (compared to recent years), and was replaced by logs as the predominant set type by some fleets. The proportion of drifting FAD sets in 2004 did not change substantially from the level of 2003 for all fleets, except the US, for which 48% of all sets in 2004 were on drifting FADs (up from 24% in 2003). The increase in sets on associated schools is typical of El Nino years, when tuna schools associated to floating objects appear to be more available to the purse seine fleets, mainly due to certain oceanographic factors. 3

ATC17/INFO.E

100% 80%

Japan
60% 40% 20% Other Drifting FAD Log Unassociated

0% 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 100% 80%

Korea
60% 40% 20%

Other Drifting FAD Log Unassociated

0% 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 100%

Percentage of total sets

PNG
80% 60% 40% 20% 0% 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 Anchored FAD Drifting FAD Log Unassociated

100% 80% 60% 40% 20%

Taiwan

Other Drifting FAD Log Unassociated

0% 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 100%
80% 60%

USA
40% 20% Drifting FAD Log Unassociated

0% 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004

Figure 5. Time series showing the percentage of total sets by school type for the major purse-seine fleets operating in the WCPO. (2004 data are provisional)

4

ATC17/INFO.E

2.3

Distribution of fishing effort and catch

11. Catch distribution in tropical areas of the WCPO is strongly influenced by El Nino–Southern Oscillation Index (ENSO) events. Figure 6 demonstrates the effect of ENSO events on the spatial distribution of the purseseine activity, with fishing effort typically distributed further to the east during El Nino years and a contraction westwards during La Nina periods. The WCPO experienced an ENSO-transitional (or neutral) period during 2001, an El Nino period during 2002 and into the first quarter of 2003, then a return to an ENSO-transitional (netural) period for the remainder of 2003. The ENSO-neutral state continued into the first half of 2004 and then moved to a weak El Niño state in the second half of 2004. There was a significant westwards shift in purse seine effort during 2003 (compared to previous years), and fishing activity was again concentrated in the western areas (PNG, FSM and the Solomon Islands) during 2004. It is also likely that most of the fishing activity will remain in the PNG, FSM and Solomon Islands area in the near future as the current ENSO-neutral state is predicted to continue until the middle of 2005. 12. The distribution of effort by set type Figure 6 (right) for the past six years shows that the establishment of the El Nino event during 2002 resulted in a higher proportion of log-associated sets east of 160°E than in the previous three years when drifting FADs were used to better aggregate schools of tuna in the absence of logs, and/or where unassociated schools were not as available in this area. The continued reduction in the use of drifting FAD sets during 2003 was probably related to the displacement of effort further west to an area where freeswimming and log-asssociated tuna schools were more available to purse seine fleets, and therefore less of a need to use drifting FADs. There was a considerable amount of log sets made during 2004 suggesting that, for one reason or another, more logs had moved into the main fishing area in recent years and had successfully aggregated tuna schools. 13. Figures 7 through 10 show the distribution of purse seine effort for the four major purse seine fleets during 2003 and 2004. As noted, there was a clear shift in fishing activities to the broad area west of 160°E longitude by all fleets in 2003 compared with effort in recent years (Figure 6). The distribution of effort by the Asian fleets in 2004 was more concentrated than in 2003, with the majority of fishing activities occurring in the area 05°N-05°S and 150°E–170°E. In 2004, the US fleet fished in an area further to the south and east and with little overlap to the main area fished by the Asian fleets (Figure 10 – left). This was also the case during 2002 (Williams and Reid, 2004). 14. Figure 11 shows the distribution of catch by species for the past six years, and Figure 12 shows the distribution of skipjack and yellowfin catch by set type for the past six years. There are some instances where the composition of the skipjack catch by set type is clearly different to the composition of the yellowfin catch by set type; for example, during 2001, unassociated sets accounted for a far greater proportion of the total yellowfin catch in the area to the east of 160°E than they did for the total skipjack catch. Higher proportions of yellowfin in the overall catch (by weight) usually occur during El Nino years as fleets have access to “pure” schools of large yellowfin that are more available in the eastern tropical areas of the WCPO. There was evidence of this in the most recent El Nino year (2002), despite it being considered an overall poor year for yellowfin catch (Langley et al., in prep.). As noted in the previous section, there were poor yellowfin catches throughout the fishery during 2004, with most of the catch coming from unassociated sets. In contrast, logs sets clearly accounted for most of the skipjack catch during 2004.

5

ATC17/INFO.E
1999 (+) 1999 (+)

2000 (+)

2000 (+)

2001 (o)

2001 (o)

2002 (-)

2002 (-)

2003 (-/o)

2003 (-/o)

2004 (-/o)

2004 (-/o)

Figure 6. Distribution of purse-seine effort (days fishing – left; sets by set type – right), 1999–2004.
(Solid–Unassociated sets; Grey–Log sets; Striped–Drifting FAD sets).
ENSO periods are denoted by “+”: La Niña; “-”: El Niño; “--”: strong El Niño; “0”: transitional period. (2004 data are incomplete)

6

ATC17/INFO.E

Japan–2003

Japan–2004

Figure 7. Distribution of effort by the Japanese purse seine fleet during 2003 and 2004
lines for the equator (0° latitude) and 160°E longitude included.

Korea–2003

Korea–2004

Figure 8. Distribution of effort by the Korean purse seine fleet during 2003 and 2004 (provisional)
lines for the equator (0° latitude) and 160°E longitude included.

Taiwan–2003

Taiwan–2004

Figure 9. Distribution of effort by the Taiwanese purse seine fleet during 2003 and 2004 (provisional)
lines for the equator (0° latitude) and 160°E longitude included.

USA–2003

USA–2004

Figure 10. Distribution of effort by the US purse seine fleet during 2003 and 2004 (provisional)
lines for the equator (0° latitude) and 160°E longitude included.

7

ATC17/INFO.E

1999 (+)

2000 (+)

2001 (o)

2002 (-)

2003 (-/o)

2004 (-/o)

Figure 11. Distribution of purse-seine catch by species, 1999–2004 (Solid–Skipjack; Grey–Yellowfin; Striped–Bigeye). ENSO periods are denoted by “+”: La Niña; “-”: El Niño; “--”: strong El Niño; “0”: transitional period. (2004 data are provisional and do not include estimates of bigeye catch)

8

ATC17/INFO.E
1999 (+)

1999 (+)

2000 (+)

2000 (+)

2001 (o)

2001 (o)

2002 (-)

2002 (-)

2003 (-/o)

2003 (-/o)

2004 (-/o)

2004 (-/o)

Figure 12. Distribution of skipjack (left) and yellowfin (right) catch by set type, 1999–2004.
(Solid–Unassociated; Grey–Log; Striped–Drifting FAD).
ENSO periods are denoted by “+”: La Niña; “-”: El Niño; “--”: strong El Niño; “0”: transitional period. (2004 data are provisional)

9

ATC17/INFO.E

2.4

Catch per unit of effort

15. Figures 13 and 14 show the annual time series of skipjack and yellowfin CPUE by vessel nation and set type, respectively. The 2004 skipjack CPUE for unassociated sets for all of the major fleets was clearly lower than in recent years (the lowest in five years for the Korean and Taiwanese fleets). In contrast, the skipjack CPUE for associated sets for most fleets increased in 2004, and skipjack CPUE for all sets was therefore similar to the level in 2003. The exception was the US fleet, which experienced very low skipjack CPUE for drifting FAD sets which contributed to a drop in all sets skipjack CPUE in 2004 for this fleet. The overall skipjack CPUE for the US fleet has steadily declined for the last five years and is now nearly half that of the Asian purse seine fleets. 16. As noted in previous sections, yellowfin catches in 2004 were generally poor and this is reflected in the CPUE graphs (Figure 14). Yellowfin CPUE for nearly all fleets and set types dropped in 2004, and were generally on par with the level of 2002, which was acknowledged to be a year of unusually low yellowfin catches. Interestingly, the exception was the yellowfin CPUE for US fleet on drifting FAD sets, which was the highest for five years. This fleet generally fished in a different area (further to the east and south) of the area fished by the Asian fleets during 2004 (Figure 10), and it appears as though they were able to catch more yellowfin, but less skipjack, from their drifting FAD sets than the Asian fleets. 17. Associated (log and drifting FAD) sets generally produce higher catch rates (mt/day) for skipjack than unassociated sets (Figure 13), yet unassociated sets produce a higher catch rate for yellowfin than associated sets. This is mainly due to unassociated sets taking large, adult yellowfin, which account for a larger catch (by weight) than the mostly juvenile yellowfin encountered in associated sets. 18. The relatively poor skipjack catch (experienced by all fleets) in the middle half of 2004 is reflected in Figure 15, although, as in 2003, there was clear evidence of a recovery by the end of the year. The consistency in the skipjack CPUE trends for the Korean and Taiwanese fleets in recent years is understood to be mainly due to the similar area fished by these fleets. The trend for the Korean and Taiwanese fleets is sometimes evident in the skipjack CPUE trend for the US fleet, although the skipjack CPUE for the US fleet is clearly lower for most of this time series, and is thought to reflect the availability of skipjack in the different areas fished by these fleets (see Figures 8–10 for the distribution of effort by these fleets during 2003 and 2004). 19. The trends in monthly yellowfin CPUE for the US fleet is more similar to that of the Korean and Taiwanese fleets than for skipjack CPUE. There are several months where very high yellowfin CPUE were experienced by the Korean and US fleets, but not for the Taiwanese fleet. In the past year, and as noted above, the yellowfin CPUE for the US fleet was higher than the two Asian fleets, further suggesting that the different area fished by the US fleet in the past year was better for yellowfin catches, but poorer for skipjack catches, than the area fished by the Asian fleets.

10

ATC17/INFO.E
JAPAN KOREA TAIWAN USA

Free-school

40 30
CPUE

20 10 0 1988 1990
JAPAN KOREA TAIWAN USA

1992

1994

1996

1998

2000

2002

2004

Log

40 30
CPUE

20 10 0 1988 1990 1992 1994 1996 1998 2000 2002 2004

40 30
CPUE

JAPAN KOREA TAIWAN USA

Drifting FAD

20 10 0 1988 1990 1992 1994 1996 1998 2000 2002 2004

40 30
CPUE

JAPAN KOREA TAIWAN USA

All set types

20 10 0 1988 1990 1992 1994 1996 1998 2000 2002 2004

Figure 13. Skipjack tuna CPUE (mt per day) by set type, and all set types combined, for selected purse seine fleets fishing in the WCPO.
Effort and CPUE were partitioned by set type according to the proportions of total sets attributed to each set type. 2004 data are provisional

11

ATC17/INFO.E

15

Free-school
JAPAN KOREA TAIWAN USA

10
CPUE

5

0 1988 1990
JAPAN KOREA TAIWAN USA

1992

1994

1996

1998

2000

2002

2004

15

Log

10
CPUE

5

0 1988 15 1990
JAPAN KOREA TAIWAN USA

1992

1994

1996

1998

2000

2002

2004

Drifting FAD

10
CPUE

5

0 1988 1990
JAPAN KOREA TAIWAN USA

1992

1994

1996

1998

2000

2002

2004

15

All set types

10
CPUE

5

0 1988 1990 1992 1994 1996 1998 2000 2002 2004

Figure 14. Yellowfin tuna CPUE (mt per day) by set type, and all set types combined, for selected purse seine fleets fishing in the WCPO.
Effort and CPUE were partitioned by set type according to the proportions of total sets attributed to each set type. 2004 data are provisional

12

ATC17/INFO.E

50 45 40
SKJ CPUE (mt/day)

Korea Taiwan KR/TW average for this time series

35 30 25 20 15 10 5 0
Jan-01 May-01 Sep-01 Jan-02 May-02 Sep-02 Jan-03 Month May-03 Sep-03 Jan-04 May-04 Sep-04

50 45 40
SKJ CPUE (mt/day)

USA KR/TW average for this time series

35 30 25 20 15 10 5 0
Jan-01 May-01 Sep-01 Jan-02 May-02 Sep-02 Jan-03 Month May-03 Sep-03 Jan-04 May-04 Sep-04

Figure 15. Monthly trends in nominal skipjack CPUE (mt per day) for Korean and Taiwanese purse seine fleets (top) and US purse seine fleet (bottom) fishing in the WCPO, 2001–2004.
20 Korea Taiwan KR/TW average for this time series

YFT CPUE (mt/day)

15

10

5

0
Jan-01 May-01 Sep-01 Jan-02 May-02 Sep-02 Jan-03 Month May-03 Sep-03 Jan-04 May-04 Sep-04

20

USA KR/TW average for this time series

YFT CPUE (mt/day)

15

10

5

0
Jan-01 May-01 Sep-01 Jan-02 May-02 Sep-02 Jan-03 Month May-03 Sep-03 Jan-04 May-04 Sep-04

Figure 16. Monthly trends in nominal yellowfin CPUE (mt per day) for Korean and Taiwanese purse seine fleets (top) and US purse seine fleet (bottom) fishing in the WCPO, 2001–2004. 13

ATC17/INFO.E

2.5

Size composition of the catch

20. Figures 17–19 show the annual catch-at-size for skipjack, yellowfin and bigeye, respectively, over the period 1999–2003 (2004 not available), comparing purse seine catch with catch from other gears in the WCPO tuna fishery. 21. Figure 17 shows that the purse-seine unassociated-set catch usually accounts for most of the large skipjack (i.e. fish over 70cm) than the pole-and-line and purse-seine associated-set (i.e. log and FAD) catch. The dominant mode in the overall skipjack catch generally falls in the range 50–60 cm range, corresponding to 1–2 year-old fish. There appeared to be a greater volume of large (60–70 cm) skipjack caught in the purse seine fishery during 2002 and 2003 compared to the other years presented here. The Philippines and Indonesian domestic fisheries take much smaller fish and account for most of the WCPO skipjack catch in 20–40 cm size range. 22. Figure 18 shows that relatively smaller yellowfin are caught in purse seine log and FAD sets than in unassociated sets. The domestic surface fisheries of the Philippines and Indonesia take large quantities of small yellowfin in the range 20–50 cm. Despite the widely held belief that purse seiners catch mainly juvenile yellowfin, a major portion of the purse seine catch in weight is also of adult (> 100 cm) yellowfin tuna. The purse-seine catch of adult yellowfin tuna is usually higher than the longline catch. Interannual variability in the size of yellowfin taken exists in each fishery. The relatively high proportion of yellowfin taken from associated purse-seine sets during 1999 corresponds to strong recruitment, with the age class of fish taken in these years present as larger fish taken in the purse seine and longline fisheries in the following years. Note the strong mode of large (130–150cm) yellowfin from (purse-seine) unassociated-sets in 2002, which corresponds to the good catches experienced in the extreme east of the tropical WCPO (Figure 12–right). 23. Figure 19 shows that the longline fishery clearly accounts for most of the catch of large bigeye in the WCPO. This is in contrast to large yellowfin tuna, which (in addition to the longline gear) are also taken in significant amounts from unassociated (free-swimming) schools in the purse seine fishery and in the Philippines handline fishery. Large bigeye are very rarely taken in the WCPO purse seine fishery and only a relatively small amount come from the handline fishery in the Philippines. Bigeye sampled in the longline fishery are predominantly adult fish with a mean size of ~130 cm FL (range 80–160 cm FL). 24. The domestic surface fisheries of the Philippines and Indonesia take small bigeye in the range 20–60 cm. Associated sets account for nearly all the bigeye catch in the WCPO purse seine fishery with considerable variation in the sizes from year to year. As with yellowfin (Figure 18), catches of medium-sized (60–100 cm) bigeye in the longline and purse seine fisheries are sometimes very low, indicating a period in their life history when this species is less vulnerable to these gears. The relatively higher proportion of bigeye taken by associated purse seine sets in 1999 corresponds to stronger recruitment in that year.

14

ATC17/INFO.E
70,000 60,000 50,000 40,000 30,000 20,000 10,000 0 10 120,000 100,000 80,000 60,000 40,000 20,000 0 10 160,000 140,000 120,000 100,000 80,000 60,000 40,000 20,000 0 10 160,000 140,000 120,000 100,000 80,000 60,000 40,000 20,000 0 10 20 30 40 50 60 70 80 20 30 40 50 60 70 80 20 30 40 50 60 70 80 90 2001 80,000 70,000 60,000 50,000 40,000 30,000 20,000 10,000 0 10 90,000 80,000 70,000 60,000 50,000 40,000 30,000 20,000 10,000 0 10 20 30 40 50 60 70 80 20 30 40 50 60 70 80 20 30 40 50 60 70 80 90 140,000 120,000 100,000 80,000 60,000 40,000 20,000 0 10 20 30 40 50 60 70 80 90 2001

Catch in thousands of fish per 2-cm size class
1999

140,000 120,000 100,000 80,000 60,000 40,000 20,000 0

Catch in weight (t) per 2-cm size class
1999

10

20

30

40

50

60

70

80

90

2000

2000

90

90

2002

2002

90

90

160,000 140,000 120,000 100,000 80,000 60,000 40,000 20,000 0 10 20 30 40 50 60 70 80

2003

120,000 100,000 80,000 60,000 40,000 20,000 0

2003

90

10

20

30

40

50

60

70

80

90

Length (cm)

Length (cm)

Figure 17. Annual catches of skipjack tuna in the WCPO by size and gear type, 1999–2003. (black–Pole-and-line;
white–Phil-Indo fisheries; grey–purse seine associated; hatching–purse seine unassociated, Phil–Indo data carried over from 2002 to 2003)

15

ATC17/INFO.E
Catch in thousands of fish per 2-cm size class
1999

16,000 14,000 12,000 10,000 8,000 6,000 4,000 2,000 0

14,000 12,000 10,000 8,000 6,000 4,000 2,000 0

Catch in weight (t) per 2-cm size class
1999

10 40,000 35,000 30,000 25,000 20,000 15,000 10,000 5,000 0 10

30

50

70

90

110 130 150 170 25,000 20,000 15,000 10,000 5,000 0

10

30

50

70

90

110 130 150 170

2000

2000

30

50

70

90

110 130 150 170

10

30

50

70

90

110 130 150 170

30,000 25,000 20,000 15,000 10,000 5,000 0 10
40,000 35,000 30,000 25,000 20,000 15,000 10,000 5,000 0 10 40,000 35,000 30,000 25,000 20,000 15,000 10,000 5,000 0 10 30 50 70 90 30 50 70 90

2001

18,000 16,000 14,000 12,000 10,000 8,000 6,000 4,000 2,000 0 10
14,000 12,000 10,000 8,000 6,000 4,000 2,000 0

2001

30

50

70

90

110 130 150 170
2002

30

50

70

90

110 130 150 170
2002

110 130 150 170 16,000 14,000 12,000 10,000 8,000 6,000 4,000 2,000 0

10

30

50

70

90

110 130 150 170

2003

2003

110 130 150 170

10

30

50

70

90

110 130 150 170

Length (cm)

Length (cm)

Figure 18. Annual catches of yellowfin tuna in the WCPO by size and gear type, 1999–2003. (black–Longline;
white–Phil-Indo fisheries; grey–purse seine associated; hatching–purse seine unassociated; Phil–Indo data carried over from 2002 to 2003)

16

ATC17/INFO.E
2,000 1,500 1,000 500 0 10 1,400 1,200 1,000 800 600 400 200 0 10 30 50 70 90 110 130 150 170 30 50 70 90 110 130 150 170 4,000 3,500 3,000 2,500 2,000 1,500 1,000 500 0 10 30 50 70 90

Catch in thousands of fish per 2-cm size class
1999

3,500 3,000 2,500 2,000 1,500 1,000 500 0 10

Catch in weight (t) per 2-cm size class
1999

30

50

70

90

110 130 150 170

2000

2000

110 130 150 170

2,500 2,000 1,500 1,000 500 0 10
3,500 3,000 2,500 2,000 1,500 1,000 500 0 10 3,500 3,000 2,500 2,000 1,500 1,000 500 0 10 30 50 70 90 30 50 70 90

2001

3,500 3,000 2,500 2,000 1,500 1,000 500 0

2001

30

50

70

90

110 130 150 170
2002 3,500 3,000 2,500 2,000 1,500 1,000 500 0 110 130 150 170 3,500 3,000 2,500 2,000 1,500 1,000 500 0 110 130 150 170

10

30

50

70

90

110 130 150 170
2002

10

30

50

70

90

110 130 150 170

2003

2003

10

30

50

70

90

110 130 150 170

Length (cm)

Length (cm)

Figure 19. Annual catches of bigeye tuna in the WCPO by size and gear type, 1999–2003. (black–Longline; white–
Phil-Indo fisheries; grey–purse seine associated; hatching–purse seine unassociated; Phil–Indo data carried over from 2002 to 2003)

17

ATC17/INFO.E

2.6

Small fish issues

25. Purse seine fleets operating in the WCPO sometimes take tuna which may be deemed too small for canning. The two main concerns related to this issue are (i) wastage (since the small tuna are usually discarded), and (ii), if the small tuna are retained, their release on the market in significant amounts may have a negative effect on price. The following information provides some indication on the extent of small fish catch in the WCPO purse seine fishery over the past few years. Since small fish are usually discarded prior to landing, observer data are the only source of information available to obtain indications of the extent of this issue. 26. Figure 20 shows the quarterly size composition of the skipjack catch for US, Taiwanese and Korean purse seine fleets according to observers, highlighting the extent of small fish in the sampled catch. Table 2 shows the percentage of small skipjack in the total sampled skipjack catch (by weight) by fleet, year and set type, and Table 3 shows the percentage of skipjack discarded (reason – too small) from the total skipjack catch (by weight) by fleet, year and set type. 27. As noted in the previous section, associated sets clearly account for more small fish than unassociated sets. While there are fewer data available for the Korean and Taiwanese fleets, the trends in size of fish taken by quarter are often consistent (overlapping) for these three fleets. Korean purse seiners appear to be taking the least amount of small fish, which would be expected since most of their sets are on free-swimming schools (unassociated sets), which, as noted, generally have larger fish than in associated sets (see Figure 5).

2 0 0 1 - 1 s t Q u a r te r

N = 11750

2 0 0 1 - 1 s t Q u a r te r

N = 2583

2 0 0 1 - 1 s t Q u a r te r

N = 598

2 n d Q u a r te r

N = 21559

2 n d Q u a r te r

N = 1830

2 n d Q u a r te r

N = 2848

3 r d Q u a r te r

N = 26089

3 r d Q u a r te r

3 r d Q u a r te r

N = 266

4 th Q u a r te r

N = 9310

4 th Q u a r te r

N = 3576

4 th Q u a r te r

N = 1368

2 0 0 2 - 1 s t Q u a r te r

N = 17191

2 0 0 2 - 1 s t Q u a r te r

N = 2437

2 0 0 2 - 1 s t Q u a r te r

N = 891

2 n d Q u a r te r

N = 23046

2 n d Q u a r te r

2 n d Q u a r te r

N = 405

3 r d Q u a r te r

N = 7395

3 r d Q u a r te r

N = 2080

3 r d Q u a r te r

N = 387

4 th Q u a r te r

N = 17551

4 th Q u a r te r

N = 1220

4 th Q u a r te r

N = 337

2 0 0 3 - 1 s t Q u a r te r

N = 9148

2 0 0 3 - 1 s t Q u a r te r

N = 852

2 0 0 3 - 1 s t Q u a r te r

N=

96

2 n d Q u a r te r

N = 4808

2 n d Q u a r te r

N=

78

2 n d Q u a r te r

N = 115

3 r d Q u a r te r

N = 6748

3 r d Q u a r te r

N=

87

3 r d Q u a r te r

N = 105

4 th Q u a r te r

N = 7294

4 th Q u a r te r

N = 1491

4 th Q u a r te r

N = 261

2 0 0 4 - 1 s t Q u a r te r

N = 10533

2 0 0 4 - 1 s t Q u a r te r

N = 3825

2 0 0 4 - 1 s t Q u a r te r

N = 2129

2 n d Q u a r te r

N = 4234

2 n d Q u a r te r

N = 1029

2 n d Q u a r te r

N = 3154

3 r d Q u a r te r

N = 1721

3 r d Q u a r te r

N = 484

3 r d Q u a r te r

20

30

40

50

60

70

80

90

20

30

40

50

60

70

80

90

20

30

40

50

60

70

80

90

Length (cm)

Length (cm)

Length (cm)

Figure 20. Quarterly skipjack length frequency, 2001–2004, collected by observers active on US (left), Taiwanese (middle) and Korean (right) purse seine vessels.
The highlighted area represents size classes 20–40 cm.

28. The Taiwanese purse seine fleet appear to take more small fish than the US and Korean fleets, but generally have fewer sets on associated schools than the US fleet. The Taiwanese fleet appear more likely to retain their small fish catch than the US fleet, since the percentage of skipjack catch reported by observers as “discarded - too 18

ATC17/INFO.E small” (Table 3) is usually less than the percentage of “small” skipjack fish sampled (for size) on Taiwanese vessels. In contrast, the percentage discarded by the US fleet is generally greater than the percentage of small skipjack reported through size sampling. There was one instance of a very high percentage of small fish in the Taiwanese fleet samples (drifting FADs in 2003), but the sample size is small (i.e. 1 or 2 sets only). 29. The degree of small skipjack catch/discard amongst the fleets does not appear to account for the fleet differences in skipjack CPUE observed in recent years (see Section 2.4).

Table 2. Percentage of skipjack <40 cms in the total weight of skipjack sampled by observers, by purse-seine fleet, year and set type, 2001–2004
Total weight of SKJ sampled (kgs) Vessel Nation KR KR KR KR TW TW TW TW US US US US Year 2001 2002 2003 2004 2001 2002 2003 2004 2001 2002 2003 2004 Unassoc. 10,655 3,852 2,540 2,815 14,368 10,239 2,207 1,836 46,778 74,945 12,789 4,145 Log 204 683 0 3,218 1,172 5,274 1,368 4,368 481 5,001 10,456 1,704 DFAD 512 85 0 1,485 3,228 1,363 131 1,143 47,590 30,803 22,059 18,693 % of SKJ weight < 40 cms Unassoc. Log DFAD 0.2% 0.0% 0.6% 1.1% 0.3% 1.0% 0.5% ########### ########### 2.1% 5.1% 0.9% 0.6% 2.0% 0.9% 3.2% 0.1% 0.1% 0.1% 0.6% 6.8% 4.0% 14.9% 9.1% 0.0% 1.7% 0.5% 11.7% 1.7% 5.3% 72.7% 5.8% 1.7% 2.4% 1.0% 6.4% TOTAL 0.2% 1.0% #NUM! 3.2% 1.2% 2.9% 8.6% 7.1% 0.9% 0.8% 0.6% 5.8%

Table 3. Percentage of total catch of skipjack reported as “discarded – too small” by observers, by purse-seine fleet, year and set type, 2001–2004
Total SKJ catch observed (MT) Vessel Nation KR KR KR KR TW TW TW TW US US US US Year 2001 2002 2003 2004 2001 2002 2003 2004 2001 2002 2003 2004 Unassoc. 2,319 1,681 794 746 4,303 2,141 709 423 9,939 12,248 2,876 1,341 Log 51 140 0 1,651 606 2,306 391 2,431 183 1,245 2,339 3,743 DFAD 137 33 0 619 909 305 97 621 12,090 6,211 5,670 4,750 % of SKJ "discarded - too small" Unassoc. Log DFAD 0.1% 55.7% 37.6% 0.1% 0.0% 0.0% 0.0% ########### ########### 0.5% 4.5% 2.1% 0.2% 0.3% 0.0% 0.4% 0.4% 1.5% 0.1% 2.7% 3.7% 1.2% 6.6% 2.8% 6.6% 15.5% 4.3% 9.4% 10.8% 3.3% 2.1% 3.1% 9.6% 18.6% 4.8% 26.0% TOTAL 3.3% 0.1% #NUM! 3.0% 2.2% 0.9% 2.3% 2.5% 5.4% 7.8% 3.4% 16.5%

19

ATC17/INFO.E

3

Summary with further observations

30. Most of the 2004 logsheet data have been received and processed, and therefore provides a good indication of what occurred last year. The 2004 purse-seine skipjack catch is likely to be higher than in 2003 and approaching the record level attained in 2002 (Lawson, 2004; Table 1 and Figure 3). The 2004 skipjack CPUE for most fleets was on par with 2003, and relatively high compared to values over the past 10–15 years, with the exception of the US fleet (Figure 13). Skipjack CPUE for the US fleet during 2004 was the lowest since 1997 and around half of the level of the Asian fleets. 31. For the first time in a number of years, logs constituted the main set type for a number of fleets during 2004 (at the expense of sets on free-swimming schools), and the high skipjack CPUE experienced for log sets was the main reason for the maintenance of relatively high overall skipjack CPUE during 2004. Skipjack catches during middle of 2004 were poor, but, as in 2003, there was a clear recovery by the end of the year (Figure 15). 32. The 2004 yellowfin catch (and CPUE) was lower than in 2003, and possibly related to a reduction in the number of unassociated sets (which tends to comprise a higher proportion of yellowfin catch by weight), although further review is required to put this in perspective with catches and catch rates experienced over the longer term. 33. Purse-seine bigeye catches are estimated from species composition data collected during port sampling. These data have shown that the proportion of bigeye in the logsheet-reported catch of yellowfin for free-swimming school sets is typically an order of magnitude smaller than for associated sets (in particular drifting FAD sets) (OFP, 2005). During 1999–2000, estimates of bigeye catches were the largest on record and this was largely attributed to the significant increase in setting on drifting FADs (Langley et al., in prep; Lawson, 2004). The increase in the number of sets on logs and drifting FADs in 2004 will contribute to a higher proportion of bigeye in the overall yellowfin catch for 2004. However, the total yellowfin-plus-bigeye catch for 2004 looks as though it will be the lowest for several years, which suggests that the total purse-seine bigeye catch (as a percentage of the total yellowfin-plus-bigeye catch) will not approach the levels attained in 1999–2000, but should be a similar level to recent years.

4

References

LANGLEY, A., J. HAMPTON, P. WILLIAMS & P. LEHODEY. (in preparation). The western and central Pacific Tuna Fishery 2003 – Overview and Status of Stocks. Tuna Fisheries Assessment Report No. 5. Oceanic Fisheries Programme, Secretariat of the Pacific Community, Noumea, New Caledonia. LAWSON, T.A. 2004. Tuna Fishery Yearbook (2003). Oceanic Fisheries Programme. Secretariat of the Pacific Community. 2004. OFP. 2005. A description of observer and port sampling data collected under the US Multilateral Treaty 2003– 2004. A paper prepared for the Annual Meeting of Parties to the South Pacific Regional US Multilateral Treaty March 17–18 2004, Nuku‟alofa, Tonga. Oceanic Fisheries Programme, Secretariat of the Pacific Community, Noumea, New Caledonia. Williams, P. & C. Reid. 2004. Overview of the western and central Pacific Ocean (WCPO) tuna fisheries, including economic conditions – 2003. 17th Meeting of the Standing Committee on Tuna and Billfish (SCTB17). Majuro, Marshall Islands. August 2004. Oceanic Fisheries Programme, Secretariat of the Pacific Community, Noumea, New Caledonia and Forum Fisheries Agency. Honiara, Solomon Islands.

20

ATC17/INFO.E

A DESCRIPTION OF OBSERVER AND PORT SAMPLING DATA COLLECTED UNDER THE US MULTILATERAL TREATY 2003–2004

A paper prepared for the Internal Meeting of Pacific Island Parties to the South Pacific Regional US Multilateral Treaty March 17–18, Nuku‟alofa, Tonga

Oceanic Fisheries Programme Secretariat of the Pacific Community

March 2005

21

ATC17/INFO.E

1

Introduction

1. This paper provides a description of the port sampling and observer data collected under the US Multilateral Treaty and provided to the Oceanic Fisheries Programme (OFP) for research purposes. Port sampling data are collected from US purse seine vessels at points of unloading (almost exclusively in Pago Pago) by the US National Marine Fisheries Service (NMFS) and provided, through the Forum Fisheries Agency (FFA), to the OFP every two months. Observer data are collected through the US Multilateral Treaty Observer programme managed by FFA and provided to the OFP on a semi-annual basis. 2. The US port sampling and observer data are routinely used with data for other fleets in the stock assessments of skipjack, yellowfin and bigeye that are conducted by the OFP and have proved to be a valuable contribution to the various tuna fishery data used by the OFP over the past 10–15 years. The length data are indicative of the agestructure of the populations and the species composition data are used to adjust the estimates of bigeye and yellowfin catches that are reported on logsheets. 3. The figures and data summaries that follow have been prepared for the immediate past calendar year (2004) and include previous years to allow comparisons to be made. 4. The final section concerns data issues and includes suggestions for facilitating the use of the data by the OFP.

2

Size composition data

5. Size data are collected from the catches of US purse seine vessels by observers and port samplers. Tables 1 and 2 provide a breakdown of the number of samples collected by month, species and set type for 2003 and 2004, for port sampling and observers, respectively. 6. The following preliminary observations have been drawn from these summaries and information available in OFP (2005).  The catch of bigeye is rarely reported accurately on purse seine catch logsheets and is typically included in the catch of yellowfin; the only way to estimate bigeye catch has been through appropriate port sampling and observer data collection. The NMFS port sampling protocol includes specific sampling of yellowfin and bigeye for the purpose of estimating the catch of bigeye. The importance of yellowfin/bigeye sampling in the NMFS port sampling protocol is reflected in the higher number of samples per unit catch for these two species relative to skipjack. (Please refer to Section 3 of this paper for further background on the work involved in estimating bigeye catch estimates in the purse seine fishery);  The (provisional) breakdown of sets undertaken by the US fleet by set type in 2004, according to logsheet data, was 30% for unassociated sets, 20% for log sets and 50% for drifting FAD sets (OFP, 2005); this is similar to the proportion of sets by set type reported by observers for 2004 (27%–unassociated; 21%–log; 52%–FAD), and in contrast to 2003, when there were slightly more unassociated sets than drifting FAD sets. The breakdown of sets undertaken by set type does not necessarily reflect the number of species size samples by set type taken from observer and port sampling data (even though there is often rough correlation). There are known to be variations in catch levels (and hence sample sizes) of species by set type and this would essentially explain such occurrences. Note that the apparent high proportion of observer samples from drifting FAD sets in 2004 will probably drop and better reflect the proportion of sets by set type according to logsheet data, once all observer size data for 2004 have been received and processed;  As reported last year, the total number of samples from observers during 2003 and 2004 was less than in previous years (OFP, 2004). This has mainly been due to the reduction in overall effort by the US purse seine fleet, which has resulted in a roughly proportional reduction in the number of samples taken, since the target observer coverage is 20% (actual observer coverage in recent years has in fact been higher than this).

22

ATC17/INFO.E Table 1. Length frequency samples (number of fish measured) taken by NMFS port samplers by month, species and school type for 2003 and 2004 (provisional).
Year Month UNASSOC 2003 1 607 2 408 3 517 4 819 5 669 6 1,408 7 1,092 8 834 9 1,044 10 1,339 11 989 12 1,558 11,284 2004 1 2 3 4 5 6 7 8 9 10 11 12 685 314 1,531 2,045 1,083 374 0 365 212 0 0 0 6,609 SKIPJACK LOG/DFAD OTHER TOTAL UNASSOC 533 51 1,191 252 472 0 880 103 578 105 1,200 131 106 164 1,089 216 166 0 835 224 593 0 2,001 207 964 100 2,156 948 584 0 1,418 936 683 0 1,727 928 1,338 0 2,677 162 322 51 1,362 426 1,829 0 3,387 1,040 8,168 471 19,923 5,573 612 1,352 446 835 699 1,600 391 987 542 0 0 0 7,464 0 1,297 0 1,666 0 1,977 0 2,880 0 1,782 0 1,974 0 391 0 1,352 0 754 0 0 0 0 0 0 0 14,073 506 833 1,461 669 337 492 0 160 209 0 0 0 4,667 YELLOWFIN LOG/DFAD OTHER TOTAL UNASSOC 1,228 0 1,480 312 1,096 0 1,199 55 1,063 0 1,194 52 214 106 536 100 996 0 1,220 0 1,343 0 1,550 0 1,330 0 2,278 156 1,416 0 2,352 59 1,838 0 2,766 0 1,937 0 2,099 159 839 0 1,265 103 2,447 0 3,487 128 15,747 106 21,426 1,124 1,082 2,330 2,119 1,310 798 1,385 594 1,569 958 69 0 0 12,214 0 1,588 54 3,217 109 3,689 0 1,979 0 1,135 0 1,877 0 594 0 1,729 0 1,167 0 69 0 0 0 0 163 17,044 61 0 125 163 167 174 0 0 0 0 0 0 690 BIGEYE LOG/DFAD 285 312 370 172 0 526 990 286 544 897 218 1,138 5,738 489 868 114 240 166 1,758 87 1,049 526 0 0 0 5,297 OTHER TOTAL 0 597 0 367 52 474 112 384 0 0 0 526 0 1,146 0 345 0 544 0 1,056 0 321 0 1,266 164 7,026 0 0 0 0 0 0 0 0 0 0 0 0 0 550 868 239 403 333 1,932 87 1,049 526 0 0 0 5,987

Table 2. Length frequency samples (number of fish measured) taken by observers on US purse seine vessels by month, species and school type for 2003 and 2004 (provisional).
Year Month UNASSOC 2003 1 783 2 195 3 654 4 914 5 272 6 272 7 7 8 26 9 330 10 25 11 211 12 0 3,689 2004 1 2 3 4 5 6 7 8 9 10 11 12 0 190 250 118 92 356 340 0 0 0 0 0 1,346 LOG 595 899 152 0 71 404 623 673 0 0 0 0 3,417 0 113 862 170 47 0 0 0 0 0 0 0 1,192 SKIPJACK DFAD OTHER TOTAL UNASSOC 434 374 2,186 109 197 40 1,331 37 149 121 1,076 306 88 102 1,104 97 46 48 437 0 95 197 968 0 122 359 1,111 118 671 280 1,650 188 781 1,054 2,165 41 672 281 978 17 1,481 534 2,226 818 3,455 640 4,095 0 8,191 4,030 19,327 1,731 2,652 1,828 3,635 1,294 292 0 50 0 0 0 0 0 9,751 0 2,652 144 2,275 221 4,968 0 1,582 297 728 1,196 1,552 1,227 1,617 104 104 0 0 0 0 0 0 0 0 3,189 15,478 0 0 0 45 24 0 0 0 0 0 0 0 69 YELLOWFIN LOG DFAD OTHER TOTAL UNASSOC 235 103 36 483 13 262 76 0 375 0 113 196 64 679 1 0 23 3 123 0 14 13 41 68 0 177 38 211 426 0 277 18 246 659 37 402 368 233 1,191 0 0 293 399 733 0 0 284 100 401 0 0 287 348 1,453 0 0 1,243 288 1,531 0 1,480 2,942 1,969 8,122 51 0 39 288 4 0 0 0 0 0 0 0 0 331 1,147 0 506 54 1,016 81 355 0 102 22 0 805 5 1,032 0 56 0 0 0 0 0 0 0 0 3,131 2,050 1,147 599 1,385 404 148 805 1,037 56 0 0 0 0 5,581 0 0 0 0 0 0 0 0 0 0 0 0 0 LOG 87 70 10 0 16 10 0 39 0 0 0 0 232 0 8 43 1 14 0 0 0 0 0 0 0 66 BIGEYE DFAD OTHER TOTAL 34 0 134 19 0 89 47 0 58 30 0 30 7 1 24 33 0 43 3 64 104 11 90 140 163 123 286 40 31 71 228 0 228 760 80 840 1,375 389 2,047 744 58 113 110 36 0 0 0 0 0 0 0 1,061 0 29 9 0 54 218 65 0 0 0 0 0 375 744 95 165 111 104 218 65 0 0 0 0 0 1,502

23

ATC17/INFO.E 7. Figures 1–3 show the coverage of port sampling and observer size composition data relative to purse seine effort during 2004. As in previous years, port sampling and observer data generally cover the purse seine effort (spatially) during this period, and the proportions of samples by set type for each 5°x5°grid are generally representative. The observer samples do not cover the extent of fishing activities at this stage, but this is expected to be more representative once all observer data for 2004 have been processed and the observer length frequency data (entered by SPC) can be linked to positional information (entered by FFA). Samples for 'other' set types represent data where school type has yet to be allocated and will be completed once all 2004 data are processed.

Figure 1 Distribution of US purse seine effort (sets) by set type during 2004
Dark grey represents unassociated sets, black represents drifting FAD and log sets and white represents 'other' sets

Figure 2 Distribution of size composition samples (number of fish measured) collected by port samplers from the US purse seine fleet by set type during 2004
Dark grey represents unassociated sets, black represents drifting FAD and log sets and white represents 'other' sets

Figure 3 Distribution of size composition samples (number of fish measured) collected by observers onboard US purse seine vessels by set type during 2004
Dark grey represents unassociated sets, black represents drifting FAD and log sets and white represents 'other' sets

24

ATC17/INFO.E 8. Figures 4–6 show the monthly size comparisons for each species by set type. The following are preliminary observations drawn from these graphs.  Generally, and in the absence of more rigorous review, the trends seen in the port sampling data are also apparent in the observer data. Similar patterns in the size data for each species reported in previous years are again evident in the 2003–2004 data. As reported in previous years, there were some instances where monthly samples were not available (or very few were taken) from one source, but have been covered by the other. For example, port sampling data appear to provide better coverage of yellowfin taken in unassociated sets compared to observer data (Figure 5–right), which reinforces the need for maintaining the two data collection sources. As in previous years, there are two modes visible in skipjack taken from associated and unassociated sets in the time series (Figure 4). There are several instances of overlap in size from the associated- and unassociated-set samples. For example, the mode of 45cm seen in the associated-set samples collected by observers for August 2002 is also apparent in the unassociated-set samples for the same month. The progression of this mode (in both set types) can be followed through to at least February 2003. Larger skipjack are more often found in unassociated sets and this is also clearly evident in Figure 4. Modal progressions of small yellowfin taken from associated sets appear annually and are generally established by October/November each year with a size of around 40–45cm (Figure 5). In the months prior to this, there are signs of even smaller (< 40cm) fish taken in sets of this type. Fewer samples were available for yellowfin taken from unassociated sets (Figure 5–right), but for months where data are available (and as seen in previous years), there is some congruence in size classes of yellowfin taken from associated sets for the same month. However, unlike the catch from associated sets, a much higher proportion of the yellowfin catch from unassociated sets tends to be large fish (> 100 cm). The presence of large yellowfin in the catch from unassociated sets is sometimes related to vessels fishing to the extreme east of the Western and central Pacific Ocean, and adjacent to the EPO fishing grounds (e.g. in and around the Line Group of Kiribati). There is some evidence that this occurred during 2002 and 2004 (OFP, 2005). Observers have access to small fish that are often discarded and therefore not available to port samplers. There is evidence of this for skipjack taken from associated sets in January 2002 (Figure 4), and for all target tuna species taken from associated sets in May 2004. The characteristics of the bigeye sampled from associated sets are similar to yellowfin, that is, they appear to recruit into the fishery at about the same time of year and the growth of the small–medium bigeye is similar to yellowfin at this size (Figure 6). However, there are very few samples of bigeye larger than 100cm, which is in contrast to yellowfin, and probably related to greater depth distribution of larger bigeye which results in there being less available to the surface fishery.









25

ATC17/INFO.E
2002 - January February March April May June July August September October November December 2003 - January February March April May June July August September October November December 2004 - January February March April May June July August September October November December
20 30 40 50 60 70 80 90

2002 - January February March April May June July August September October November December 2003 - January February March April May June July August September October November December 2004 - January February March April May June July August September October November December
20 30 40 50 60 70 80 90

Length (cm)

Length (cm)

Figure 4. Size comparison of skipjack sampled from US purse-seine catch from associated (left) and unassociated (right) sets by port samplers (red line) and observers (grey fill), 2002–2004 26

ATC17/INFO.E
2002 - January February March April May June July August September October November December 2003 - January February March April May June July August September October November December 2004 - January February March April May June July August September October November December
20 40 60 80 100 120 140 160

2002 - January February March April May June July August September October November December 2003 - January February March April May June July August September October November December 2004 - January February March April May June July August September October November December
20 40 60 80 100 120 140 160

Length (cm)

Length (cm)

Figure 5. Size comparison of yellowfin sampled from US purse-seine catch from associated (left) and unassociated school sets (right) by port samplers (red line) and observers (grey fill), 2002–2004 27

ATC17/INFO.E
2002 - January February March April May June July August September October November December 2003 - January February March April May June July August September October November December 2004 - January February March April May June July August September October November December
20 40 60 80 100 120 140 160

2002 - January February March April May June July August September October November December 2003 - January February March April May June July August September October November December 2004 - January February March April May June July August September October November December
20 40 60 80 100 120 140 160

Length (cm)

Length (cm)

Figure 6. Size comparison of bigeye sampled from US purse-seine catch from associated (left) and unassociated school sets (right) by port samplers (red line) and observers (grey fill), 2002–2004 28

ATC17/INFO.E

3

Species composition in the target catch

9. Bigeye catches are rarely reported accurately on vessel logsheets and, in most cases, bigeye catch is reported with the yellowfin catch, since it is very difficult to distinguish juvenile bigeye from juvenile yellowfin in the net or in the brails coming on-board, and there is no economic incentive to consider the catch of juvenile yellowfin/bigeye tuna separately. Recent stock assessment work conducted on bigeye (summarised in Langley et al., in prep.) suggest that the significant increase in catches and the fishing mortality of juvenile bigeye by purse seine and other fleets towards the end of the 1990s and into 2000, may have pushed the catch level to near the maximum sustainable with the present age-specific exploitation pattern. The need to have more accurate estimates of the purse-seine bigeye catch for stock assessment work has therefore focussed more effort on the review of data collection during recent years, as has been reported in previous versions of this paper and continuing work in this area is expected in the coming years. 10. Species composition data are collected from the catches of US purse seine vessels by NMFS port samplers. One of the main uses of these data is to produce estimates of the proportion of bigeye expected in the logsheetreported catch of yellowfin, a process undertaken by NMFS. Observers measure and record the species and length of individual target tuna samples extracted from the catch of each set. The protocol requires the observer to randomly take a certain number of target tuna from each brail loaded onto the vessel; in this way, the bigger the catch, the more number of brails that are loaded and hence, the more samples taken. By applying the total catch in the set to the number of samples by species, an estimate of species composition from the set catch can be obtained. Accumulating data for many observed sets provides some indication of the proportion of bigeye in the yellowfin– bigeye catch. 11. Table 3 provides an example of the contrast in the species composition of yellowfin and bigeye between associated and unassociated school sets (note that data have not been screened for data quality in this summary). Evident in this summary is the high degree of consistency in the percentage composition of bigeye in the „yellowfin plus bigeye‟ catch within each set type over the years, and the distinct difference between the set types (i.e. much higher proportion of bigeye in associated sets). The relatively higher proportion of bigeye in unassociated sets during 2004, compared to other years, is probably due to the low sample size during that year (i.e. only 15 sets observered). Table 3. Annual proportion of bigeye in the combined yellowfin–bigeye catch, by set type, according to observers active on US purse seine vessels, 1997–2004
Associated sets Unassociated sets YFT BET % BET in YFT BET % BET in catch catch YFT+BET Sets catch catch YFT+BET (MT) (MT) catch observed (MT) (MT) catch 6,148 1,894 23.6% 201 4,468 75 1.7% 4,611 1,620 26.0% 194 4,667 15 0.3% 10,512 3,656 25.8% 11 99 0 0.0% 10,161 2,410 19.2% 47 672 5 0.7% 6,074 2,145 26.1% 277 3,334 90 2.6% 2,729 694 20.3% 373 6,156 25 0.4% 2,974 1,057 26.2% 52 1,239 41 3.2% 3,823 1,151 23.1% 15 339 28 7.7%

Year 1997 1998 1999 2000 2001 2002 2003 2004

Sets observed 594 496 589 542 525 241 338 365

'Sets observed' include sets where there were yellowfin in the catch, but no bigeye, and sets where there were bigeye, but no yellowfin in the catch. Data for 2004 are incomplete at this stage. MT – Metric tonnes.

12. In regard to the adjustment of bigeye and yellowfin catch estimates using species composition data, the OFP has examined the proportion of bigeye in „yellowfin plus bigeye‟ caught by purse seiners of all flags in the Western and Central Pacific Ocean (Lawson 2003) and found that while the practise of using school association alone to predict the proportion of bigeye in yellowfin plus bigeye was acceptable, the prediction suffers from moderate lack of fit. Better results were obtained when year and flag were also included in the model. Size group (i.e., bigeye and yellowfin greater than or less than 9 kg) was found to be unrelated when school association is the first variable in the model, since these two variables are confounded. 29

ATC17/INFO.E 13. The study also examined the difference between the proportion of bigeye in 'yellowfin plus bigeye' determined from the US port sampling for 1988-1995, on the one hand, and the US port sampling data for 19962001 and observer data for all flags for 1998-2001, on the other. The proportion for associated sets determined from the US port sampling data for 1988-1995 is 13.2%, while the proportion for associated sets determined from the US port sampling data for 1997-2001 and the observer data for 1998-2001 is much higher, 32.0% and 23.7% respectively. The reasons for the large difference between 1988-1995 and 1996 onwards are unknown. It is important to determine the causes of the increase, since this will affect how the input data for the MULTIFAN-CL assessments of bigeye and yellowfin are adjusted. Currently, the assessments are conducted using different sets of input data that have been adjusted based on different assumptions regarding the representivity of the US port sampling data for 1988-1995. 14. The OFP plans to conduct further work in regard to the adjustment of input data for the MULTIFAN-CL assessments and the estimation of annual catches of yellowfin and bigeye by purse seiners in the WCPO.

4 Bycatch and discards data
15. Bycatch and discards data are collected from US purse seine vessels by observers at the fishing operation (set) level. Tables 4 and 5 show the discard rate by species and set type for 2003 and 2004, respectively, according to observers. The following observations have been drawn from these statistics:  The discard rate by set type (with more than 50 sets observed) for skipjack was between 0.3% and 9.0% for 2003 and from 3.5% to 34.3%, in 2004. For yellowfin, the ranges were 2.0% to 4.5% for 2003 and 0.5% to 20.3% for 2004. For bigeye, the ranges were 0.0% to 2.9% for 2003, and 0.0% to 27.9% for 2004. The predominant reason for discard in both years was fish too small for canning, with gear damage and vessel fully loaded as the other main reasons for discard. As is typically the case, associated-school sets accounted for higher rates of target catch discard than unassociated-school sets, presumably due to there being more small fish associated with drifting FADs than unassociated schools (see Figures 4–6). For example, observers reported a skipjack discard rate of 34.3% for the drifting FAD sets during 2004 compared with only 3.5% for schools feeding on baitfish and unassociated schools. The higher proportion of discards in 2004 suggests that smaller fish were more available in the areas fished by the US purse seine fleet compared to 2003;  The proportion of bycatch discarded, as expected, was high (83.5% for 2003 and 87.2% for 2004). In all cases, the reason for retaining bycatch, according to the observer, was for crew consumption;  Overall bycatch for both years was consistent and reported to be around 0.2–3.0% of the total catch, according to observer data; this is similar to the level of bycatch observed in previous years. Associated set types are acknowledged to account for a higher percentage of bycatch (in the total catch) than unassociated sets. For example, bycatch from log sets was 3.0% and 2.3% of the total catch for this set type in 2003 and 2004, respectively. This is in contrast to level of bycatch from unassociated-school set types (schools feeding on baitfish), which was at only 0.4% and 0.2% of the total catch (from unassociated sets) , for 2003 and 2004 respectively. As reported in previous years, sets on logs tend to produce a higher percentage (and more diversity) of bycatch than sets on drifting FADs; for example, the percentage of bycatch from drifting FAD sets for both 2003 and 2004 was only 0.5%, which is 5–6 times less than the percentage bycatch taken from log sets. This is understood to be due to logs spending a longer period in the water than drifting FADs, and therefore more time to „accumulate‟ a variety of bycatch species. 16. Tables 6 and 7 show the breakdown of bycatch species recorded by observers during 2003 and 2004. The following observations have been drawn from these statistics:  As in previous years, rainbow runner, silky shark, oceanic whitetip shark, wahoo, mahi mahi and barracudas appear to be the most common medium–large bycatch species encountered in purse seine sets. Some of these species are often encountered in large numbers in sets (e.g. Rainbow runner), while others may be encountered in a relatively high proportion of sets, but each time, only in very small numbers (e.g. barracuda). Mackerel Scad and Oceanic triggerfish are typically the most common small fish encountered in purse seine sets;

30





 





ATC17/INFO.E There were five observations of marine turtle encounters during 2003, and none during 2004. In all cases the turtles were reported to have been released alive and unharmed. Unfortunately, three marine turtles were not identified to the species level. During 2003, observers recorded only one set with marine mammal (pilot whale) interaction; Three animals were involved and all were released alive and unharmed. There were no observed marine mammal encounters during 2004, based on the information data processed to date. It is interesting to note that adult albacore tuna, more prevalent in sub-tropical and temperate waters, are sometimes encountered in the tropical purse seine fishery (once in every 100 sets, on average); As in previous years, black marlin and blue marlin are by far the most commonly encountered billfish species in purse seine sets. During 2003 and 2004, observers encountered these species on average once every 10–20 sets with no distinct pattern with regard to frequency by set type (perhaps a slightly higher frequency with log sets). As has been reported in previous years, the relatively high proportion of black marlin (to blue marlin) in the purse seine catch compared to the longline fishery over the same area (i.e. equatorial WCPO) is unusual and no doubt requires further investigation; Certain bycatch are usually retained for crew consumption. It is normal practice that species such as billfish, mahi mahi and wahoo are retained for both crew meals and as food for families of crew members on return to port. As reported previously, barracudas are particularly sought-after by Pacific Island crew; As reported in previous years, the ability of the observers to identify bycatch continues to improve, with around 50 marine animals now identified to the genus level. “Unidentified sharks” and “Other species unspecified” were two categories that constituted a high proportion of the bycatch reported by observers several years ago, but they now make up only a small proportion of the bycatch reported by observers.

31

ATC17/INFO.E Table 4. Target species, bycatch and discard breakdown by set type for the US purse seine fleet during 20037, determined from unraised observer data representing approximately 20% coverage.

OBSERVATIONS
Catch Type of sets
Anchored raft, FAD or Payao

Number of sets Species 1 SKIPJACK YELLOWFIN BIGEYE BY-CATCH 81 SKIPJACK YELLOWFIN BIGEYE BY-CATCH SKIPJACK YELLOWFIN BIGEYE BY-CATCH SKIPJACK YELLOWFIN BIGEYE BY-CATCH SKIPJACK YELLOWFIN BIGEYE BY-CATCH SKIPJACK YELLOWFIN BIGEYE BY-CATCH SKIPJACK YELLOWFIN BIGEYE BY-CATCH SKIPJACK YELLOWFIN BIGEYE BY-CATCH SKIPJACK YELLOWFIN BIGEYE BY-CATCH SKIPJACK YELLOWFIN BIGEYE BY-CATCH

Metric Tons MT / set % Total % Discarded 38.1 38.1 99.8% 4.7% 0.0 0.0% 0.0 0.0% 0.1 0.1 0.2% 100.0% 1,349.8 552.3 61.4 95.2 6,937.9 2,503.8 1,042.5 53.2 1,638.9 881.1 25.0 11.3 64.6 33.3 0.8 0.1 19.2 28.3 0.0 2.5 1,912.1 249.6 109.5 19.6 0.0 0.0 0.0 0.0 335.1 131.0 0.0 2.7 12,295.7 4,379.4 1,239.3 184.6 16.7 6.8 0.8 1.2 21.8 7.9 3.3 0.2 9.6 5.2 0.2 0.1 8.1 4.2 0.1 0.0 3.8 5.7 0.5 27.3 3.6 1.6 0.3 7.6 3.0 0.1 17.6 6.3 1.8 0.3 65.6% 26.8% 4.6% 3.0% 65.8% 23.8% 9.9% 0.5% 64.1% 34.5% 1.0% 0.4% 65.4% 33.7% 0.8% 0.1% 38.4% 56.7% 4.9% 83.5% 10.9% 4.8% 0.9% 71.5% 27.9% 0.6% 67.9% 24.2% 6.8% 1.0% 2.4% 1.1% 0.3% 83.2% 9.0% 4.5% 2.9% 81.7% 0.3% 2.0% 0.0% 73.9% 0.3% 0.7% 0.0% 100.0% 0.7% 0.1% 0.0% 100.0% 2.3% 1.0% 2.0% 92.0% 0.0% 0.0% 0.0% 0.0% 0.0% 1.1% 0.0% 94.7% 5.8% 3.2% 2.6% 83.5%

Drifting log, debris or dead animal

Drifting raft, FAD or Payao

318

Feeding on Baitfish

170

Live Whale

8

Live Whale Shark

5

No information

70

Other (Please specify)

1

Unassociated

44

Total

698

MT – Metric tonnes

7

refers to the year when the observer started the trip.

32

ATC17/INFO.E Table 5. Target species, bycatch and discard breakdown by set type for the US purse seine fleet during 20048, determined from unraised observer data representing approximately 10–15% coverage.
(Data for 2004 should be considered as preliminary)

OBSERVATIONS
Type of sets
Anchored raft, FAD or Payao

Number of sets Species 37 SKIPJACK YELLOWFIN BIGEYE BY-CATCH 100 SKIPJACK YELLOWFIN BIGEYE BY-CATCH SKIPJACK YELLOWFIN BIGEYE BY-CATCH SKIPJACK YELLOWFIN BIGEYE BY-CATCH SKIPJACK YELLOWFIN BIGEYE BY-CATCH SKIPJACK YELLOWFIN BIGEYE BY-CATCH SKIPJACK YELLOWFIN BIGEYE BY-CATCH SKIPJACK YELLOWFIN BIGEYE BY-CATCH SKIPJACK YELLOWFIN BIGEYE BY-CATCH SKIPJACK YELLOWFIN BIGEYE BY-CATCH

Catch Metric Tons MT / set % Total % Discarded 616.3 16.7 74.4% 8.0% 123.0 3.3 14.9% 7.0% 79.0 2.1 9.6% 7.7% 9.5 0.3 1.2% 80.2% 2,790.5 652.8 352.7 89.1 3,103.9 2,159.6 484.8 28.8 819.5 338.5 28.0 2.1 0.0 18.9 0.0 0.0 0.0 0.0 0.0 0.0 728.8 398.9 134.1 18.4 0.0 0.0 0.0 0.0 448.8 0.1 0.1 3.3 8,507.7 3,691.9 1,078.8 151.1 27.9 6.5 3.5 0.9 19.4 13.5 3.0 0.2 9.9 4.1 0.3 0.0 9.5 12.4 6.8 2.3 0.3 9.8 0.1 17.4 7.6 2.2 0.3 71.8% 16.8% 9.1% 2.3% 53.7% 37.4% 8.4% 0.5% 69.0% 28.5% 2.4% 0.2% 100.0% 56.9% 31.2% 10.5% 1.4% 99.2% 0.0% 0.0% 0.7% 63.4% 27.5% 8.0% 1.1% 12.5% 20.3% 27.9% 93.0% 34.3% 13.4% 16.9% 78.4% 3.5% 0.5% 0.0% 94.8% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 23.0% 16.7% 25.8% 84.6% 0.0% 0.0% 0.0% 0.0% 3.5% 84.6% 100.0% 37.2% 19.7% 13.5% 20.5% 87.2%

Drifting log, debris or dead animal

Drifting raft, FAD or Payao

160

Feeding on Baitfish

83

Live Whale

2

Live Whale Shark

1

No information

59

Other (Please specify)

0

Unassociated

46

Total

488

MT – Metric tonnes
8

refers to the year when the observer started the trip.

33

ATC17/INFO.E Table 6. Bycatch species taken by the US purse seine fleet during 2003 and 2004, determined from unraised observer data representing 20% coverage. 9
(MT – Metric tonnes; Data for 2004 should be considered preliminary at this stage)
2003 Sets Species Billfish BLACK MARLIN BLUE MARLIN SAILFISH (INDO-PACIFIC) SHORT-BILLED SPEARFISH STRIPED MARLIN SWORDFISH Sharks and Rays BLACKTIP SHARK BLUE SHARK HAMMERHEAD SHARKS MAKO SHARKS MANTA RAYS (UNIDENTIFIED) OCEANIC WHITETIP SHARK PELAGIC STING-RAY RAYS (TORPEDINIDAE, NARKIDAE) SHARKS (UNIDENTIFIED) SILKY SHARK THRESHER SHARKS NEI WHALE SHARK Other tunas, tuna-like species ALBACORE BULLET TUNA FRIGATE AND BULLET TUNAS FRIGATE TUNA KAWAKAWA MACKEREL (UNIDENTIFIED) WAHOO Others AMBERJACKS BARRACUDAS (UNIDENTIFIED) BATFISHES BLACK TRIGGERFISH DRUMMER (BLUE CHUB) FILEFISH (SCRIBBLED LEATHERJACKET) FILEFISH (UNICORN LEATHERJACKET) FILEFISHES GREAT BARRACUDA MACKEREL SCAD / SABA MAHI MAHI MAN-O-WAR FISH OCEAN SUNFISH OCEANIC TRIGGERFISH (UNIDENTIFIED) PILOT FISH POMFRETS AND OCEAN BREAMS PORCUPINE FISH RAINBOW RUNNER SARGENT MAJOR SQUIDS TREVALLIES (UNIDENTIFIED - JACKS) TRIPLE-TAIL UNSPECIFIED % Freq. Freq. MT CATCH % discarded Sets kgs / set4 % Freq. Freq. MT
10

2004 (provisional) CATCH % discarded

kgs / set4

60 23 4 1 18 2

8.6% 3.3% 0.5% 0.1% 2.5% 0.2%

9.91 4.01 0.25 0.01 2.23 0.73

75.9% 14.20 91.9% 5.74 11.7% 0.36 0.0% 0.01 76.8% 3.19 85.8% 1.05

47 26 3 1 3 1

9.6% 5.3% 0.6% 0.2% 0.6% 0.2%

7.92 4.24 0.11 0.04 0.74 0.11

88.8% 77.3% 81.6% 0.0% 100.0% 100.0%

15.90 8.51 0.22 0.08 1.49 0.22

45 6.4% 2 0.2% 7 1.0% 19 2.7% 73 10.4% 57 8.1% 153 21.9% 18 2.5% 3 0.4%

1.54 0.08 0.06 2.81 9.10 8.21 17.88 0.78 3.00

98.7% 2.21 100.0% 0.11 100.0% 0.09 100.0% 4.03 100.0% 13.04 99.7% 11.76 100.0% 25.62 100.0% 1.12 100.0% 4.30

1 0.2% 2 0.4% 16 3.2% 5 1.0% 42 8.6% 1 0.2% 1 0.2% 35 7.1% 163 33.4% 3 0.6% 1 0.2%

0.02 0.42 0.65 0.75 2.74 0.01 0.01 3.26 20.30 0.11 1.00

100.0% 100.0% 100.0% 100.0% 100.0% 100.0% 100.0% 98.5% 99.8% 100.0% 100.0%

0.04 0.84 1.31 1.51 5.50 0.02 0.02 6.55 40.76 0.22 2.01

7 1.0% 54 7.7% 1 0.1% 12 1.7% 1 0.1% 27 3.8% 131 18.7%

0.38 10.70 0.02 0.35 0.00 4.39 2.45

0.0% 0.54 99.4% 15.33 0.0% 0.03 45.8% 0.50 0.0% 0.00 89.1% 6.29 38.0% 3.51

5 1.0% 13 2.6% 6 1.2% 28 5.7% 153 31.3%

1.44 6.42 0.07 1.24 8.36

0.0% 100.0% 12.5% 90.1% 27.3%

2.89 12.89 0.14 2.49 16.79

1 57 8 10 23 1 9 6 78 185 3 1 161 5 212 1 29 6 20

0.1% 8.1% 1.1% 1.4% 3.3% 0.1% 1.2% 0.8% 11.1% 26.5% 0.4% 0.1% 23.0% 0.7% 30.3% 0.1% 4.1% 0.8% 2.8%

0.09 0.74 0.03 3.03 1.01 0.00 0.08 0.20 16.85 10.80 0.00 0.04 13.26 0.02 55.04 0.00 1.05 0.03 3.03

0.0% 23.9% 59.3% 99.0% 42.3% 100.0% 97.6% 64.8% 90.2% 27.0% 0.0% 100.0% 99.7% 30.0% 80.5% 0.0% 14.8% 6.9% 56.0%

0.13 1.06 0.04 4.34 1.45 0.00 0.11 0.29 24.14 15.47 0.00 0.06 19.00 0.03 78.85 0.00 1.50 0.04 4.34

10 35 4 23 31 1 12 8 56 99 3 164 1 12 2 185 9 3 27 2 25

2.0% 7.1% 0.8% 4.7% 6.3% 0.2% 2.4% 1.6% 11.4% 20.2% 0.6% 33.6% 0.2% 2.4% 0.4% 37.9% 1.8% 0.6% 5.5% 0.4% 5.1%

0.29 1.22 0.08 0.36 0.73 0.01 0.08 0.57 16.55 5.59 1.16 6.76 0.00 0.21 0.01 55.48 0.08 0.01 0.53 0.02 1.32

19.5% 0.58 28.8% 2.45 89.7% 0.16 94.4% 0.72 59.6% 1.47 0.0% 0.02 61.2% 0.16 22.8% 1.14 90.4% 33.23 16.2% 11.22 99.8% 2.33 98.6% 13.57 0.0% 0.00 8.6% 0.42 100.0% 0.02 99.5% 111.41 0.0% 0.16 50.0% 0.02 22.2% 1.06 0.0% 0.04 77.9% 2.65

TOTALS

184.19

151.02

9 10

The catch of unidentified tuna has not been counted as bycatch. "kgs/set" refers to the weight of this bycatch per observed set.

34

ATC17/INFO.E Table 7. Marine reptiles and mammals species encountered by the US purse seine fleet during 2003 and 2004, determined from unraised observer data representing 20% coverage.
11

(No. – number of individuals; Data for 2004 should be considered preliminary at this stage)
2003 Sets Species Marine Mammals MARINE MAMMAL (UNIDENTIFIED) Marine reptiles GREEN TURTLE HAWKSBILL TURTLE MARINE TURTLE (UNIDENTIFIED) % Freq. Freq. No. CATCH % discarded No. / set5 2004 (provisional) CATCH % % No. discarded Freq. Freq. Sets

No. / set5

1

0.1%

3

100.0% 0.004

-

-

-

-

-

1 1 3

0.1% 0.1% 0.4%

1 1 3

100.0% 0.001 100.0% 0.001 100.0% 0.004

-

-

-

-

-

5

Data issues

17. Work related to observer data quality and debriefing continued during 2004. A workshop looking at improving techniques in observer debriefing will be held at SPC in March 2005 and will involve the OFP Fisheries Monitoring Supervisor, the US Treaty Observer Programme Officer and a selection of regional observer coordinators. 18. The port sampling length frequency data provided by NMFS currently groups samples taken from log sets with samples taken from drifting FAD sets into one set type referred to as “floating objects” (Set type = 4). The stock assessment analyses conducted by OFP scientists have not needed to distinguish between these two set types at this stage, but it is envisaged that studies will need to differentiate between samples from logs sets and samples from drifting FAD sets in the future. For this reason, we request that the port sampling length frequency data differentiate between log and drifting FAD sets. It is understood that the procedures involved in port sampling at Pago Pago require the port sampler to refer to the catch logsheet to obtain, inter alia, the set type for the well being sampled. It appears that there is no provision in the data processing of the NMFS port sampling data collection forms for the entry of samples from drifting FAD sets distinct from a log set (i.e. there is only one code for “floating objects”). Any advice on this matter would be most appreciated. 19. The suggestion to review the NMFS port sampling protocol in recent years has been welcomed by the OFP. The current NMFS port sampling protocol has been used for more than ten years now, and while the review may not identify significant deficiencies, it is nonetheless considered a worthwhile exercise to ensure it is appropriate with respect to what has evolved in the WCPO purse seine fishery over the past 5–10 years. This review may also serve to provide guidelines and recommendations for the review of sampling of other purse seine fleets operating in the region.

6

References

LANGLEY, A., J. HAMPTON, P. WILLIAMS & P. LEHODEY. (in preparation). The western and central Pacific Tuna Fishery 2003 – Overview and Status of Stocks. Tuna Fisheries Assessment Report No. 6. Oceanic Fisheries Programme, Secretariat of the Pacific Community, Noumea, New Caledonia. LAWSON, T.A. 2004. Tuna Fishery Yearbook (2003). Oceanic Fisheries Programme. Secretariat of the Pacific Community. 2004. OFP. 2004. A description of observer and port sampling data collected under the US Multilateral Treaty 2002– 2003. A paper prepared for the Annual Meeting of Parties to the South Pacific Regional US Multilateral Treaty. March 1–2, 2004, Funafuti, Tuvalu. Oceanic Fisheries Programme, Secretariat of the Pacific Community, Noumea, New Caledonia. OFP. 2005. A preliminary review of the western and central Pacific Ocean purse seine fishery 2004. A paper prepared for the Annual Meeting of Parties to the South Pacific Regional US Multilateral Treaty March 17– 18, 2005, Nuku‟alofa, Tonga. Oceanic Fisheries Programme, Secretariat of the Pacific Community, Noumea, New Caledonia.

11

“No./set" refers to the number of this bycatch per observed set.

35


				
DOCUMENT INFO
Jun Wang Jun Wang Dr
About Some of Those documents come from internet for research purpose,if you have the copyrights of one of them,tell me by mail vixychina@gmail.com.Thank you!