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;All of these issues must be understood if the relationship between Indonesian coastal and offshore tuna fisheries is to be addressed. Two short papers cover the above subjects: this study covering item 1, and Mathews et al. (1996) addresses items 2 and 3. A third study is scheduled to examine the effects of rumpon on catch rate in the EEZ in the Biak area north of Cendrawasi Bay in Irian Jaya. Comprehensive studies of the biological, economic and management implications have been made by Monintja and Mathews (1995), and Mathews and Monintja (1996).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.Philippine rumpon are normally located in waters 400-4,000 m deep, usually less than 3,000 m. In North Sulawesi waters this implies that many, if not all, rumpon are situated in or near coastal waters, i.e., from 12-15 nm (21-27 km) to a maximum of 50 nm (90 km) from the coast. In practise rumpon may be as little as 5-10 nm from the coast. In addition many Philippine-owned and operated rumpon are situated in territorial waters, e.g., the Maluku Sea, to the east of Sulawesi, and in the area between Sangihe and Talaud Islands, all of which are included in Indonesian territorial waters (Mathews and Monintja, 1996).
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), orBoth funai and huhate vessels tend to operate within 20-30 nm of the North Sulawesi shore, often much closer. Some of the larger boats fish around rumpon further offshore, a few of which are owned by Indonesian operators. The GPS positions of more than 300 rumpon in Indonesian waters are provided by Mathews and Monintja (1996); position accuracy is reported to be less than 200 m).· 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)Yellowfin fishery
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 1989.3.2.2 Bitung fisheries
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; andFigure 3. Manado landings of yellowfin tuna.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)Table 4. Manado yellowfin tuna fishery: catch, effort and CPUE.
|
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 |
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 |
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 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.4. CONCLUSIONSNB 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 indicatedAPPENDIX 2NB(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)Table A3. Catch (mt) and CPUE (total gross mt/set) for Philippine purse seine fishery in offshore Indonesian waters (N EEZ), 1993-95.
|
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
|
Seasonal summary, 1993-95
|
|||||||||||||||
First Quarter |
Second Quarter |
Third Quarter |
Fourth Quarter |
Mean CPUE/Quarter |
4 MEAN annual CPUE/month |
|||||||||||
Jan |
Feb |
Mar |
Apr |
May |
Jun |
Jul |
Aug |
Sep |
Oct |
Nov |
Dec |
1 |
2 |
3 |
||
1993 |
|
|
|
|
|
|
0.54 |
0.60 |
0.94 |
|
|
NA |
NA |
0.69 |
NA |
0.69 |
1994 |
0.19 |
0.34 |
0.43 |
0.50 |
0.35 |
0.29 |
0.57 |
0.48 |
0.73 |
|
|
0.32 |
0.38 |
0.52 |
NA |
0.44 |
1995 |
0.20 |
0.20 |
0.37 |
0.52 |
0.57 |
0.43 |
0.47 |
0.38 |
0.22 |
|
|
0.28 |
0.51 |
0.35 |
NA |
0.37 |
MEAN, months |
0.20 |
0.27 |
0.40 |
0.51 |
0.48 |
0.36 |
0.56 |
0.48 |
0.63 |
|
|
|
|
|
|
|