Studies of Indonesian tuna fisheries, Part 1: Interactions between coastal and offshore tuna fisheries in Manado and Bitung, North Sulawesi¹

¹ The original paper presented at the Shimizu meeting ("The interaction between the artisanal and industrial tuna fisheries in the eastern Indonesia with special reference to Sulawesi Sea" by N. Naamin) has been revised extensively based on reviewers' comments. The present paper represents one segment of the original paper.

Nurzali Naamin
Research Institute for Marine Fisheries
Komplek Pelabuhan Perikanan Samudera
J1. Muara Baru Ujung
Jakarta 14440 Indonesia

C.P. Mathews
Central Institute for Fisheries Investigations, and
Marine Coastal Ecosystems and Processes Project, Jakarta, Indonesia

D. Monintja
Fakultas Perikanan, Institute Pertanian, Bogor, and
Marine Coastal Ecosystems and Processes Project, Jakarta, Indonesia

ABSTRACT

Since 1990 an important offshore industrial tuna fishery has been established in northern Indonesian waters. This fishery is theoretically confined to the EEZ, but in practice it occupies large areas of territorial and archipelagic waters. Fishing is carried out by "sets" or groups of boats based on a single purse seiner, supported by carrier and smaller patrol boats. These groups fish around rumpon (FADs) deployed in waters from 200-4,000 m deep, and take substantial catches, most of which is landed directly into General Santos City and other southern Philippine ports. The offshore fishery lands more than 50,00 mt per year from waters around North Sulawesi and northern Irian Jaya. Coastal fishing is carried out for skipjack by two kinds of small pole-and-line vessels ("funai": 5-15 GT; "huhate": 20-30 GT) in North Sulawesi. The coastal fishery landed less than 9,000 mt of skipjack in 1989, the last year before large scale offshore fishing commenced. Data for Manado and Bitung (North Sulawesi) were analysed to determine the effects of the offshore fishery on the skipjack and yellowfin fisheries based in these cities. Skipjack CPUE fell in Manado (from 50-70 mt/boat/year in 1980 to less than 20 mt/boat/year in 1992) and Bitung (from more than 100 mt/boat/year in 1980 to about 60 mt/boat/year in 1990). Effort on skipjack in Bitung rose slowly from approximately 40 boats in 1986 to more than 100 boats in 1991, and then fell to under 35 boats in 1995; the decline was probably due to competition with the industrial fishery. Industrial CPUE fell from 0.69 mt of tuna/GT of effort/year in 1993 to 0.37 mt/GT in 1995. Available data are insufficient for a complete analysis of offshore-onshore tuna fishery interactions. Nevertheless it is likely that industrial, offshore tuna fishing impacted the coastal fisheries in Manado and Bitung by reducing the amount of skipjack and yellowfin available to the coastal fishery.

1. INTRODUCTION

Since 1990 there has been increasing concern about interactions between the Indonesian coastal and industrial yellowfin and skipjack fisheries. The Indonesian industrial fisheries appear to have been impacted by the large industrial fishery developed primarily by large Philippine companies working in the Sulawesi Sea and elsewhere in Indonesian waters (Mathews and Monintja, 1996). This new Philippine fishery is based on large purse seiners operating around fish aggregating devices (FADs) called "payao" in the Philippines and "rumpon" in Indonesia.

Fisheries based on rumpon have existed in Indonesia since time immemorial (Monintja, 1993). Rumpon affect skipjack and yellowfin catchability and abundance. They may also make the stocks more susceptible to overfishing (Mathews and Monintja, 1996). Effects of rumpon on tuna fishing must be taken into account when addressing some of the concerns being raised about the coastal and offshore tuna fisheries in the Sulawesi Sea and elsewhere in Indonesian waters.

Recent studies on tuna fisheries in and around the Indonesian province of North Sulawesi have produced some of the data that are needed to identify:

1. interactions between coastal (Indonesian) and offshore (largely foreign) fishing fleets targeted toward skipjack and yellowfin;

2. some interactions between rumpon, involving fishing gear used to catch tunas and small pelagic fish, the latter mostly scad; and

3. changes in yellowfin abundance, especially on fishing grounds along the north coast of Gulf of Tomini.

2. METHODS AND DATA SOURCES

For the two studies reported here, secondary data were obtained during a total of eight weeks of surveys carried out in North Sulawesi Province. Data were obtained from (1) the Provincial Fisheries Service (Dinas Perikanan Tingkat I, i.e., Level One, located in Manado, the Provincial capital) and the county or city Fisheries Services (Dinas Perikanan Tingkat II, or Level II, located in Manado city, Bitung city, Gorontalo city, Gorontalo county, Tondano, capital of Minahasa county: and Kotamobagu, capital of Bolaang Mongondow county; see Figure 1), and (2) interviews by C.P. Mathews and D. Monintja with experienced Fisheries Service personnel in all of these locations to assess the accuracy and reliability of data in the light of the sampling systems used, experience of key personnel and the facilities available. These authors also carried out additional interviews with experienced fishermen and fishing managers/operators in Kwandang, Inobonto, Tanawangko, Manado, and Likupang on the north and northwest coast. Bitung, Belang, and Gorontalo on the west and southwest coast were also visited. Access to points between Belang and Gorontalo (Figure 1) was precluded by floods and the destruction of roads and bridges during the recent rainy season in North Sulawesi. Results including qualifications about the accuracy of the data obtained are provided later, and (3) interviews with managers and fishermen from several Indonesian and foreign (Philippine and Taiwanese) fishing companies. All of the Indonesian and some of the foreign companies provided useful data and described their fishing strategies in detail.

Figure 1. Map of the study area. Shading indicates payao deployment.

3. RESULTS AND DISCUSSION

3.1 Boats and Gear

3.1.1 The coastal tuna fisheries for skipjack and yellowfin

Coastal tuna fishing has been carried out in Indonesia since historical periods using traditional vessels and a wide variety of gear. During the 1950s, pole-and-line fishing was introduced in North Sulawesi; data on catch and effort are only available since 1976. These data are published annually in the Provincial Fisheries Statistics (Buku Tahunan Statistik Perikanan, Propinsi Sulawesi Utara, 1976-1994; Manado, Sulawesi Utara).

Data on effort were originally based on catch and effort surveys usually carried out at the Tingkat II level, but for some time Tingkat I data have been based on the number of new and extant fishing permits (izin). Effort data from some Tingkat II, e.g., at Bitung are, however, still based on annual surveys and were found to be reliable when checked by means of direct censuses carried out through fishermen interviews. Where differences between Provincial and city or county effort data were found, the latter were used as they were believed to be more accurate.

Landings data are collected at county or city (Tingkat II) offices and sent to the Provincial (Tingkat I) office where some adjustments are usually made. From about 1990 foreign vessels started to catch substantial quantities of skipjack and yellowfin in offshore waters; much of the catch was landed directly in ports of southern Philippines and Taiwan. Although all of these landings are supposed to be declared to authorities in Bitung, Fisheries Service personnel believe only a small proportion of actual offshore (mainly foreign) catches are declared. Therefore, it was not possible to separate the offshore (mainly foreign) from the coastal (entirely Indonesian) landings in Bitung.

Provincial data are supposed to include all of the landings from North Sulawesi waters, including those made by foreign vessels operating in the adjacent EEZ. However, because of incomplete reporting by foreign vessels and related data collection problems, it was not possible to obtain accurate estimates of either coastal or offshore (largely foreign) tuna landings for most of North Sulawesi from 1990 onwards; Philippine and other foreign vessels were licensed to operate in large numbers starting in 1990. Data prior to 1990 are not influenced by foreign landings.

These data problems complicate and introduce uncertainties in the assessment of the effects of foreign offshore landings on local (primarily coastal) landings. Where possible, city and county landings and effort data were used as they are based on surveys and direct observations. Provincial landings data were also used, while taking account the above mentioned problems where necessary.

3.1.2 Philippine rumpon

Large numbers of rumpon were introduced by Philippine operators into the Indonesian EEZ (i.e., offshore from 12 nm) in 1990. Around 200 rumpon were licensed and deployed off Manado and west of the Sangihe Islands (northern waters of Sulawesi), with additional larger numbers of rumpon placed elsewhere in Indonesian waters in later years (Mathews and Monintja, unpublished report, PUSLITBANGKAN, Jakarta; Mathews and Monintja, 1996). Normally Philippine fishermen operate a purse seiner "set"² or "group" with each unit covering 10-20 rumpon. Each group 1 consists of one catcher vessel (40-450 GT) accompanied by 2-3 carrier boats and 1-2 searcher boats. The searcher boats patrol the rumpon primarily to identify those that have attracted tuna schools. Searcher boats may also assist catcher boats by using powerful lights to attract tuna at night, making the tuna more vulnerable to purse seining. Searcher boats are also sufficiently large to dissuade most coastal Indonesian boats from fishing near rumpon: many reports have been received showing that Philippine fishermen interpose their larger boats between the smaller Indonesian coastal vessels and the rumpon around which the skipjack and yellowfin tend to aggregate. Reports of attempts by large foreign boats to ram small coastal vessels may have arisen from such attempts at interposition. Catcher boats are directed by searcher boats to rumpon that have attracted large schools, and fish caught are passed directly to carrier boats for transport. Most catches are then sent directly to southern Philippine ports such as General Santos City. The searcher boats play a most important role as it takes some time for a rumpon which has provided a successful set (usually 5-25 mt; Monintja, 1993), to attract sufficient fish to justify a new set (usually five days or more are needed between sets around a rumpon). Routine patrolling ensures that catcher boats do not waste time searching around rumpon that have attracted only small schools of tuna. The support given by the rest of the group allows the catcher boats to spend most of their time fishing. Therefore, purse seiner groups have a much higher fishing power than purse seiners operating independently.

²The term "set" is used in two distinct ways in the industrial tuna fishery: (a) a "set" may be a group of boats that combine to fish tuna; and (b) a "set" may be a single operation involving the laying and recovery of the purse seine net: i.e., a set may have a zero catch. The term "set" is reserved here for the second meaning.

3.1.3 Taiwanese and other longliners

Since about 1990 there has been a very significant increase in the number of Taiwanese longliners operating in the Indonesian EEZ and in territorial/nusantara (internal, archipelagic) waters of Indonesia. These boats catch yellowfin and are also thought to compete with Indonesian coastal fishermen. Boats may be up to or in excess of 100 GT.

3.1.4 Indonesian vessels

Most of the skipjack pole-and-line vessels are small (<300 GT), and may include:

· 5-15 GT vessels, locally called "funai" and using small numbers (about 10) of long poles (around 5-6 m long), or

· 20-30 GT pole-and-line vessels, locally called "huhate" and using larger numbers (20-30) of smaller poles (around 3-4 m long). The fishing power of one huhate is equivalent to about two funai.

Yellowfin are usually caught by small (<5 GT) boats operating handlines or troll lines. In addition, some longliners from 5-50 GT operate in Sulawesi waters. Many of the small boats are grouped into cooperatives ("plasma") that may be associated with particular fish processing plants in Bitung or elsewhere.

3.2 The Fisheries

3.2.1 Manado fisheries

Skipjack fishery

Data on Manado landings were taken from the Manado City Fisheries Service and are of two kinds: (a) market sales volume which include the species composition, and (b) the total Manado City landings for which species composition is not available.

Skipjack in Manado are taken by funai and by troll lines (pancing tonda). A conversion factor of 10 troll lines to one funai may be used. The conversion factor is based on fisherman and operator interviews and inspection of fishing units (Table 1). Some fish are landed in the Manado City Market, while some are distributed directly to restaurants, small smoking plants and other outlets.

By assuming arbitrarily that the same proportion of fish is landed outside and inside the Manado City Market throughout the time series, it was possible to estimate the amount of skipjack landed from 1985-1995 (Table 2).

Catch and effort data for the Manado skipjack fishery are summarized in Table 3. The catches show levels of 1,000-2,000 mt/year, peaking in 1986-87 (Table 3, Figure 2). After large numbers of rumpon were introduced by Philippine companies in 1990, the catches fell to 900 mt (1990) and then to <600 mt (1992). There was a small increase in landings from 1993-95, probably caused by coastal fishermen working from small handline boats around foreign rumpon. The CPUE was generally high (40-80 mt/standard funai-pole-and-line boat) prior to the installation of rumpon in 1990. From 1990-95, the CPUE fell to about 15-25 mt/standard pole-and-line boat. This suggests that there was a distinct reduction in catch rates due to competition between coastal and foreign offshore fishermen operating around Philippine-owned rumpon.

Figure 2. The Manado skipjack tuna fishery: catch (lower boxes), effort, and CPUE.

Table 1. Manado skipjack tuna fishery: estimated of total effort.

	a	b	c
	No Pole and	Troll	Total nominal effort
	Line boats	Lines	(pole and liners)
1985	10	156	256
1986	10	198	298
1987	14	161	30.1
1988	16	120	28.0
1989	17	96	26.6
1990	25	104	35.4
1991	25	132	38.2
1992	25	135	38.5
1993	24	135	37.5
1994	25	135	38.5
1995	20	187	38.7

NB: 10 troll lines are equivalent to one Funai type of pole and line boat (see text)
c = a+(b/10)

It was not possible to identify an unequivocal effort measure for the yellowfin fishery which uses handlines, because effort data for pelagic and demersal hook-and-line fisheries are not recorded separately. Table 4 and Figure 3 show the estimated landings data. Yellowfin are taken by small handline boats in shallow waters or sometimes around rumpon. Foreign fishermen tend not to prevent small handliners from targeting yellowfin around rumpon as this species is not taken in large numbers by purse seiners operating around rumpon near Manado. Yellowfin landings peaked in 1990-91, at about 500 mt/year, and then landings fell to 349 met in 1995.

Table 2. Manado skipjack fishery: estimated landings.

	Estimation of total skipjack landings
	a	b	c (from d)	(c/b)xa	d	e	e/d
	Skipjack Catch. T (market)	Total Catch (all spp),T (market)	Total Marine Catch (all areas, spp)	Total Skipjack Catch, All areas	Total marine Fish 1	Total Fish	Ratio
			T		t	t
1985	228.1	1150.4	6253.5	1240.0	6253.5	6253.5	1.0000
1986	400.5	1280.1	6718.2	2101.9	6718.2	6718.2	1.0000
1987	4239	1107.7	6724.9	2573,5	6724.9	6724.9	1.0000
1988	263.7	985.5	6862.1	1836.1	6862.1	6862.1	1.0000
1989	204.8	1151.3	6432.3	1144.2	6432.3	6432.2	1.0000
1990	176.4	1100.4	5731.0	918.7	5731.0	6026.0	1.0515
1991	124.0	900.3	6155.1	847.5	6155.1	6497.8	1.0557
1992	105.3	1103.7	5968.9	569.7	5968.9	6357.3	1.0651
1993	151.2	1171.3	6104.1	788.1	6104.1	6832.4	1.1193
1994	139.7	1005.6	6227.5	865.5	6227.5	7062.9	1.1341
1995	1302	784.3	6181.0	1026.4	6181.0	7010.0	1.1341

NB: Negligible amounts freshwater fish were landed into Manado prior to 1989.

Skipjack fishery

Skipjack in the Bitung fishery are mostly caught by the large pole-and-line boats (huhate). Only the effort data of the Bitung skipjack fishery were judged to be unbiased (Appendix 1, Table A1) and show a fluctuating but generally steady effort from 1980-89, with fluctuating but generally declining CPUE (Table 5, Figure 4). This implies:

1. coastal effort was not sufficient to impact the abundance of that part of the skipjack stock accessible to coastal fishing; and

2. the CPUE of the coastal fishery from 1980-89 was probably responding to other influences, e.g., foreign effort on the stock (not including Philippine rumpon at this time), or to environmental parameters.

Table 3. Manado skipjack tuna fishery: catch, effort and CPUE.

	Catch	Effort (IP standard	CPUE
	T/year	Pole and Line Boats)	T/Boat year
1985	12400	256	4644
1986	21019	298	7053
1967	25735	301	8550
1966	1836.1	280	6557
1969	11442	266	43.01
1990	9187	354	25.95
1991	847.5	362	22.18
1992	569.7	38.5	1480
1993	788.1	37.5	21,02
1994	865.5	36.5	22.48
1995	1026.4	38.7	2652

NB: In Manado City pole and liners ore of the "funai" type (see text for description)

	a	b	c (fromd. Table 2)	(c/b)xa
	Yellofin	Total Catch	Total Manne Catch	Total Yellowfin
	Catch, T	(all spp).T	(all areas. spp)	Catch. All areas
	(market)	(market)	T
1965	1649	11504	62535	896
1966	4919	1280.1	67182	2581
1967	119.1	11077	67249	722.8
1966	104.1	9655	68621	7251
1969	846	1151.3	64323	472.9
1990	99.9	11004	5731.0	520.3
1991	73.6	900.3	61561	5034
1992	85.0	1103.7	59669	459.6
1993	82.8	1171.3	6104.1	431.6
1994	66.0	10056	6227.5	4066
1995	44.3	784.3	6161.0	349.2

Table 5. Bitung skipjack tuna fishery: catch, effort and CPUE.

a	b	c	d=b/c
	All Sulawesi	Effort	CPUE
	T	(Standard Bitung pole/liners)
1980	10383	87.97	118.03
1981	7479	96.48	77.52
1982	9834	104.56	94.05
1983	9606	113.79	84.42
1984	8492	112.80	75,29
1985	5942	95.52	62.20
1986	6617	84.89	77.94
1987	7478	116.78	64.04
1988	8543	122.58	69.69
1989	8647	142.20	60.80
1990	12263	129.51	94.69
1991	12263	134.41	91.23
1992	15803	124.31	127.12
1993	18199	125.18	145.38

BOLD: data Include purse seiner (foreign) landings and effort,

These data are not comparable with data prior to 1990, which do not include substantial foreign landings. See Table A1.

Figure 4. The Bitung skipjack tuna fishery: catch, effort and CPUE.

From 1991-95 many pole-and-line boats were withdrawn voluntarily from the fishery, and between 1993-94, another 30 boats were repossessed through bank foreclosures in fishermen who failed to meet debt requirements (Fisheries Service, Bitung, and interviews). Fishermen and boat managers were unanimous in blaming decreasing catch rates and declining catches for the reduction in number of pole-and-line boats. This reduction started soon after the introduction of Philippine rumpon in waters adjacent to those occupied by coastal fishermen; the domestic fishermen were largely excluded from fishing around the rumpon by the sailing tactics of foreign fishermen.

Provincial data from 1980-89 (Table 5, column d) cover only the coastal Indonesian fishery as offshore foreign landings were low and were not directed towards North Sulawesi ports. From 1990 onwards an unknown amount of offshore foreign landings (probably large relative to coastal landings) was included in the North Sulawesi landings. The sharp increase in CPUE and estimated standard effort from 1990 onwards are therefore due to biases, and data from 1990 onwards are not comparable with data prior to 1990.

Table 6 and Appendix 2 (Tables A2 and A3) provide some estimates of CPUE for Philippine purse seine sets. The time series is short but does suggest that there was a sharp decline in overall CPUE from 0.69 mt of tuna/GT to 0.37 mt of tuna/GT. Similar trends were reported by company officials from about 1990-95; unfortunately, it was not possible to obtain data from 1990-93. The observed decreases in CPUE suggest that the industrial fishery working offshore may have reduced landings and CPUE in the near-shore fishery from 1993-94; a period when effort fell from 91 to 56 pole-and-line boats.

Table 6. CPUE for industrial purse seine sets operating in Indonesian EEZ, archipelagic and territorial waters.

Mean CPUE/Set/morrth
1	2	3	4	MEAN CPUE/set/month
NA	NA	0.69	NA	069
0.32	0.38	0.62	NA	044
0.26	0.51	0.35	NA	0.37

Yellowfin fishery

Yellowfin are taken with handlines in the coastal fishery around Bitung. As in the Manado fishery, hook-and-line data for pelagic and demersal fish are pooled so that effort and CPUE cannot be estimated for yellowfin in the Bitung coastal fishery.

Estimates of yellowfin landings from the Provincial statistics are summarised in Table 7, together with landings for some other areas and for all of North Sulawesi. Data for Manado, Gorontalo and all North Sulawesi from 1990 onwards are not comparable with data prior to 1990 since the offshore, industrial landings caused a very marked increase in total landings. The decline in landings from 1990-91 was probably caused by competition between coastal and industrial landings; the increase from 1991-94 was probably caused by a substantial increase in declarations of yellowfin landings (not necessarily in actual landings) by foreign vessels fishing in the EEZ.

Table 7. North Sulawesi yellowfin tuna fishery (based on provincial data).

	Bitung	Manado	Gorontaio City	Gorontaio County	All Sulawesi
	T	T			T
1980	59	347	272	1091	3125
1981	80	837	1395	4657	7931
1982	138	648	1052	4360	7264
1983	206	769	1164	3656	6864
1984	288	772	1187	3541	6867
1985	236	493	842	3436	6010
1986	162	432	2278	3941	5901
1987	341	444	451	3655	6207
1988	810	435	1282	2618	6686
1989	1142	990	186	2987	7862
1990	2048	738	1593	2692	9063
1991					6429
1992	2165	636	1643	1476	7813
1993					12093
1994	14018	235	760	1122	18539
1995

NB 1: Yellowfin landings are predominantly from the above areas.

NB 2: Decreasing yellowfin landings occur everywhere except in Bitung, where significant errors were introduced by offshore landings.

NB 3: Data in this table are taken from Provincial (Tingkat 1), not from city and county statistics (Tingkat II) and may be less accurate (see text).

The number of Bitung boats targeting skipjack fell from more than 100 pole-and-line boats in 1991 to less than 35 boats in 1995; the decline occurred shortly after the introduction of Philippine rumpon into Indonesian EEZ and territorial waters.

By 1995 the industrial CPUE fell to 23% of 1993 levels; the decline was from a mean of 0.94 mt of tuna/GT to 0.22 mt of tuna/GT.

Industrial skipjack landings were at least 30,000-40,000 mt in 1994 and landings may have exceeded 50,000 mt in 1990 (Mathews and Monintja, 1996).

Total skipjack landings from North Sulawesi and Irian Jaya waters were at least 50,000 mt/year and may have exceeded 70,000-80,000 mt/year from 1990-95; prior to 1989 total landings were much lower at <25,000-30,000 mt/year (Mathews and Monintja, 1996). Industrial landings were over 50% of total landings taken in northern Indonesian waters, perhaps by a substantial margin from 1990 onward.

It is likely that industrial effort expended around rumpon by foreign boats competed with and reduced coastal skipjack landings around Bitung and Manado, the principal fishing ports for skipjack.

Effort and CPUE data for yellowfin are lacking for Bitung and Manado (but see Mathews et al., 1996a). Manado yellowfin catches declined after the introduction of rumpon in 1990.

5. REFERENCES CITED

Mathews, C.P., and D.R. Monintja. 1996. Assessment of the role of foreign and industrial tuna fishing in Indonesia's EEZ, archipelagic and territorial waters. Report, PUSLITBANGKAN, Central Research Institute for Fisheries Research, Jakarta.

Mathews, C.P., D. Monintja and N. Naamin. 1996. Studies of Indonesian tuna fisheries: Part 2 - Changes in yellowfin abundance in the Gulf of Tomini and North Sulawesi. In: Shomura, R.S., J. Majkowski and R.F. Harman (eds.). Scientific Papers from the Second FAO Expert Consultation on Interactions of Pacific Tuna Fisheries, 23-31 January 1995, Shimizu, Japan. [This volume]

Monintja, D.R. 1993. Study on the development of rumpon as fish aggregating devices. Martek: Bulletin T.J.K. 3(3): 1-137.

Monintja, D.R., and C.P. Mathews. 1995. Fisheries and administrative management in the North Indonesian Coastal Zone, 1995 report.

APPENDIX 1

Provincial vs City and County Data Sets

Table A1 summarises available catch and effort data for the skipjack fishery in Manado and Bitung (where most of the Indonesian skipjack landings and effort in North Sulawesi are concentrated) and for all North Sulawesi. Effort data for Bitung are the most accurate; the data were tested in 1995 by means of direct census based on fisherman interviews. The number of pole-and-line boats counted by name during this census (37 boats) was in close agreement with the preliminary estimate (about 30 boats) provided informally by the Fisheries Service in Bitung. Manado and Provincial effort estimates were less accurate. Bitung effort was therefore used to standardise skipjack effort for the entire time series.

North Sulawesi landings data form 1990 onwards included foreign landings. An attempt to clarify the data series by adjusting total recorded landings for skipjack exports (all believed to be made from foreign landings) failed to give results in accord with the experience of the fishermen who reported lower pole-and-line landings from 1992, leading directly to a reduction in number of boats. The data for the period from 1990 onwards (Table 5, columns b-d) are biased by unknown amounts of landings from foreign vessels. These landings are probably only a small portion of total foreign catches made in Indonesian waters; they are probably large relative to total North Sulawesi coastal landings and so a cause of serious bias in estimates of coastal landings. Derived data for CPUE (Table A1, i-k, o) and for total standardised effort (Table A1, column l) will also be biased and cannot be used in any assessment. Only effort data for Bitung are known to be unbiased.

Table A1. Catch and effort data for the skipjack tuna fishery in Manado, Bitung and North Sulawesi.

ANCILARY DATA, not used in the assessment
a		bc	d	e	f	g	h	i	j	k	l=(d/l)	m	n	o=(n/k) adj CPUE
	Bitung	Manado	All Sulawesi	Bitung	Manado	All Sulawesi	Bitung	CPUE	CPUE	CPUE	Standard Effort	Exports	All Sulawesi (Adj. For Exports)
	T	T	T	Effort	Effort	Effort	Effort	Bitung	Manodo	All Sulawesi	All Sulawesi
	...	...	...	(pola/line)	(pola/line)	(pole/line)	(pole/line)	T/boat.year	T/boat.year	T/boat.year	Bitung pole/liners	T	T	T/boat year
1960	7790.1	1690	10383.4	66	14	198	66	118.03	12.07	52.44	87.97	0	10383	118.03
1981	51161	4495	7478.8	66	13.3	186	66	77.52	3380	40.21	96.48	0	7478.8	77.52
1982	65836	345.8	98336	70	13.3	174	70	9405	26.00	56.51	104.56	0	9833.6	94.05
1983	5909.7	8890	9606.4	70	13.3	159	70	8442	66.84	60.42	113.79	0	9606.4	84.42
1984	4893.6	891.2	8492.3	65	13.3	155	65	75.29	67.01	54.79	112.80	0	8492.3	75.29
1986	298S.6	807,7	5941.5	48	13.3	138	48	62.20	60.73	43.06	95.52	0	5941.5	62.20
1986	3196.7	1020.0	6616.9	41	13.3	132	41	7794	76.69	50.13	84.89	0	6616.9	7794
1987	3073.7	1372.2	7477.9	48	13.3	140	48	64.04	103.17	53.41	116.78	0	7477.9	64.04
1988	3972.6	3398.4	8543.1	57	11	141	57	69.69	30895	6059	122.58	1513	7030.1	57.35
1985	4073.9	1330.2	8646.5	67	15	151	67	6080	88.68	57.26	14220	2290	6356.5	44.70
1990	7480.7	19329	12263.4	79	43	161	79	9469	44.95	76.17	12961	2296	9967.4	7696
1991	9397.0	1893.8	122630	87	28	155	103	9123	67.64	79.12	134.41	826	11437	85.09
1992	11313.9	1854.7	158029	134	43	215	89	127.12	43.13	7350	124.31	3577	12225.9	9835
1983	13229.6	1815.6	18199.2				91	145.38			125.18	4878	133212	106.41
1994	22030.9	717.8	26553.3	87	28	155	56	393.41	25.64	171.31	67.50		265533	393.41
1995							35.5	0.00

NB: ALL DATA FROM BUKU STATISTIK PERIKANAN TAHUNAN PROPINSI SULAWESI UTARA. (Nofft SiJawesi Pnnftwe Flenedes SWstics. Manndo. North Suhwos): unless indicated

NB(A): Skipjack effort expended mostly in Bitung

(i) estimated from Provincial data; (ii) from fisherman surveys in Bitung City.

*** Unadjusted for exports (=Philippine and other foreign landlings).

NB(B):Datum for Bitung effort in 1980 was erroneously given as 166 boats.

NB(C): Bitug CPUE (T/boat.year) was used to standardise effort. (I.n.o)

BOLD: from (e).

Underlined: interpolated Underlined+Italics:extrapolated

## Exports estimated from data on frozen, smoked, fresh and sashimi products Included in landings by Dinas Perikanan, but not landed by pole and lines

Industrial Catch, Effort and CPUE

No data on total Philippine catch and effort from Indonesian EEZ and territorial waters are available. Data from one Philippine company which operates purse seine sets were made available and were used to estimate industrial CPUE (Table A2). The structure of a purse seine set is described in Table A2 and in the text. Table A3 summarises the data on Philippine industrial fishing in the Indonesian EEZ.

Table A2. Fishing power of Philippine purse seine fleet. A standard set is composed of one catcher, 2-3 carriers and 2-3 light boats.

Set 1	GT	HP
Catcher	45.50	195.00
carrier	35.01	195.00
Carrier	35.78	180.00
Lightboat	5.47	70.00
Lightboat	4.96	65.00
Lightboat	5.47	220.00
Total	132.19	935.00
Set 2
Catcher	86.34	220.00
Carrier	31.40	280.00
Carrier	28.10	198.00
Carrier	64.74	195.00
Lightboat	5.97	63.00
Lightboat	5.97	18.00
Lightboat	13.67	65.00
Total	236.19	1008.00
Set 3
Catcher	44.61	280.00
Carrier	34.60	220.00
Carrier	66.44	220.00
Lightboat	5.47	150.00
Lightboat	4.62	65.00
Lightboat	17.76	190.00
Total	173.70	1096.00
Set 4
Catcher	49.22	220.00
Carrier	57.00	190.00
Carrier	57.33	180.00
Lightboat	5.47	68.00
Lightboat	7.39	190.00
Lightboat	4.86	88.00
Total	181.27	910.00
Set 5
Catcher	49.7S	220.00
Carrier	30.71	180.00
Carrier	28.38	100.00
Lightboat	14.15	110.00
Lightboat	11.28	80.00
Lightboat	8.57	120.00
Total	142.81	810.00
Set 6
Catcher	154.68	200.00
Carrier	96.43	195.00
Carrier	96.43	195.00
Lightboat	9.48	65.00
Lightboat	14.89	80.00
Lightboat	18.92	100.00
Total	387.80	835.00
Set 7
Catcher	54.29	335.00
Carrier	60.80	250.00
Carrier	27.07	190.00
UghUioat	12.60	65.00
Lightboat	6.73	65.00
Lightboat	16.80	225.00
Total	178.29	1130.00
Set 8
Catcher	155.90	425.00
Carrier	51.20	190.00
Carrier	40.25	250.00
Lightboat	10.37	190.00
Total	257.72	1055.00
Set 9
Catcher	134.73	365.00
Carrier	65.52	290.00
LIghtboat	45.94	190.00
Lightboat	12.27	150.00
Total	258.46	995.00
Overall	1948.13	8773.00
Set 10	216.46	974.78

NB: Set10 estimated aa (Overall/9)

	Total Gt	1993			1994									1995
		Jul	Aug	Sep	Jan	Feb	Mar	Apr	Miy	Jun	Jul	Aug	Sep	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sept
Set 1	132-19	45.5	176.5	189	18.085	21.667	68.421	38.496	20.465	13.029	139.098	26.071	141.344	24.98		71.177	142.938	152.668
		0.34	1.34	1.43	0.14	0.16	0.50	0.29	0.15	0.10	1.05	0.20	1.07	0.19		0.54	1.08	1.15
Set 2	236.19	112.1	13.8		71.M7	73.468	104.387	68.885		12.582	8.12	42.514	156.074	24.414	71.242	129.152	124.487	127.726
		0.47	0.08		0.33	0.31	0.44	0.29		0.05	0.03	0.18	0.68	0.10	0.30	0.55	0.53	0.54
Set 3	173.70	169.2	61		26..834	62.092	99.135	173.622	131.258	21.113	211.347	10.437				90.93	124.09	51.427	162.592	72.48	115.433	10.114
		0.07	0.35		0.16	0.36	0.57	1.00	0.76	0.12	1.22	0.06				0.47	0.71	0.30	0.94	0.42	0.66	0.05
Set 4	181.27	30.5	128.2	271	22.53	32.969	84.854		58.977	121.884		247.535	168.238						27.442	37.558	92.078	15.408
		0.22	0.71	1.50	0.12	0.18	0.47		0.33	0.67		1.37	0.93						0.15	0.48	0.51	0.09
Set 5	142.81																		58.97
																			0.41
Set 6	387.50																86.447	104.183	55.061	113.652	15.722	176.516
																	0.22	0.27	0.14	0.29	0.04	0.46
Set 7	178. 20	113.5	96.9	64.6	40.843	99.582	87.451	83.171	84.023	91.278	99.737	113.604	43.3	20.85		46.961	75.36	18.6	66.75	71.79	67.729	74.82
		0.64	0.54	0.36	0.23	0.58	0.49	0.47	0.47	0.51	0.56	0.64	0.24	0.12		0.26	0.42	0.10	0.37	0.40	0.38	0.42
Set 8	257.72														53.053	45.672	45.256	54.042			48.338	29.169
															0.21	0.18	0.18	0.21			0.19	0.11
Set 9	258.46	147.083		117.19		116.742	33.256	110.533	108.886		122.247	111.285			54.994	57.047
		0.57		0.45		0.45	0.13	0.43	0.42		0.47	0.43			0.21	0.22
Set 10	216.46													86.801	12.971			176.984	126.218	164.902	87.738	43.617
														0.40	0.06			0.62	0.58	0.78	0.41	0.20
N		6	5	4	6	1	6	5	6	5	5	6	4	4	4	6	6	7	6	5	6	6
Mean		0.54	0.60	0.94	0.34	0.34	0.43	0.50	0.35	0.29	0.67	0.48	0.73	0.20	0.20	0.37	0.52	0.57	0.43	0.47	0.36	0.22

NB:N = no of observation