INTRODUCTION

Makalah Falsafah Sains (PPs 702)

Program Pasca Sarjana / S3

Institut Pertanian Bogor

Januari 2002

Dosen:

Prof Dr Ir Rudy C Tarumingkeng (Penanggung Jawab)

Analysis of Commercial Catch Per Unit Effort Data of Trawl Fisheries in Indonesian Exclusive Economic Zone of Malacca Straits*

By:

Kiagus Abdul Aziz

E-mail: aziz_ka@yahoo.com

Abstract

Legal fishing activities in Indonesian Exclusive Economic Zone are dominated by trawl fisheries. The number and the size of trawlers operated in this area have been increased from year to year. Up to 1995 the largest size of trawlers in this areas was only 75 GT and 60 % of them were trawlers with the size smaller than 50 GT. In 1999 among the 95 licensed trawlers operated in the area, 52 % were those with the size larger than 100 GT and only 26 % of them with the size smaller than 50 GT.

The increase of CPUE most likely due to the use of additional devices, such as fish finder and might also be due to the fishing masters have got more familiar with the fishing grounds, so they did not have to waste their time to reach the fishing ground. Besides, they might fish beyond the traditional fishing grounds. Therefore this increase might not reflect the relative fish abundance in the water but it rather indicated the increase of catchability of the trawlers. Whatever the reason of the increase of CPUE, it may be concluded that there were no indicators of overfishing in this area. This conclusion was supported by the fact that the species composition of the catches between 1993 to 1999 were relatively constant. There were 110 species recorded in the trawl catch.

Introduction

Fishery resources in the Indonesian Exclusive Economic Zone of the Malacca Straits which consist of pelagic and demersal fishes as well as shrimp and other marine species, have been exploited intensively by legal traditional and modern fishing of Indonesian fishermen and illegal fishing of Indonesian and foreign fishermen. It is needed, therefore, to formulate some alternatives of fishery resource management strategies in order to minimize the negative impact of fishing activities on the fish stock. In 1997 shrimp and demersal fish contributed about 40 % of the catch from the Malacca Starits (Aziz, 1998). Shrimp is one of the economicly important target species of trawl fisheries in the Staits. In 1996 shrimp catch from the Malacca Straits was about 20 % of the whole shrimp catch from the Indonesian waters (Aziz et al., 1997)

Fishery resource management is aimed to maintain the sustainable fishery resource, which can provide maximum benefit to all fishermen and be sustained without affecting the long term productivity of the stock Gulland, 1983). It means that the fishery resource management should include the empowerment of traditional fishermen. This aim can be reached only by increasing the efficiency of fishery resource utilization rationally. Therefore the practice of responsible fisheries should be applied to avoid over fishing and over-investment. Such strategy will guarantee the sustainable fisheries development.

Formulation of the fishery resource management strategies in the Indonesian Exclusive Economic Zone of the Malacca Straits requires information of the biology of the fish stock and the fishing activities in the area. This study was aimed to evaluate fishing activities in the Indonesian Exclusive Economic Zone of the Malacca Straits and the response of the fish stock to the fishing activities.

Methods

This study was carried out in June to September1999. The primary data collected includes total catch, species composition of the catch, catch per unit effort, total number and size of fishing vessels, and fishing ground. These data were collected through direct observation and from log book of some fishing vessels.

Catch Per Unit Effort (CPUE) data used in this study were commercial catch data, recorded from 1993 to 1999. A fishing trip, the trawl operation between 7 – 10 days, was applied as a unit effort. For analyzing CPUE, the trawler sizes were grouped into 5 categories, i. e. smaller than 30 GT, 30 to 50 GT, 50 to 75 GT, 75 to 100 GT and larger than 100 GT. Catch per unit effort (CPUE) was used as an index of relative stock abundance (Gulland, 1975). When the value of CPUE is high, we can expect that the abundance oh fish resource in the area is high. On the other hand when the value of CPUE is low, we can expect that the abundance oh fish resource in the area is low. How ever if the catchability of a fishing gear is not constant, the CPUE may not show the index of relative abundance accurately. The changes of the catchability of a fishing gear may due to the use of fish finder. Therefore in this study the possible changes of the catchability of a fishing gear should be taken into consideration when analaysing the trend of CPUE .

Results

Catch per unit effort of different type of boats recorded from May 1993 to April 1999 is presented in Table 1, while yearly average of catch per unit effort is presented in Table 2. There were 110 species recorded from trawl fisheries in 1998 and 1999. Monthly average of catch per unit effort (kg) of major species in 1998 and 1999 is presented in Table 3.

Table 1. Average catch per unit effort (kg) for different types of boats from 1993 t0 1999. (May 1993 - Apr 1994)
Type of boats		No of boats	May	Jun	Jul	Agu	Sep	Oct	Nov	Dec	Jan	Feb	Mar	Apr
< 30 GT		1	6747.00	7705.33	7123.75	6840.00	5489.67	7782.50	5395.25	8602.33	5779.00	9666.00	7516.25	7741.75
30 - 50 GT		17	6293.04	5718.07	5634.00	5959.03	5796.62	5675.44	5810.30	8017.95	6414.32	6598.94	5521.23	6211.73
50 - 75 GT		2	7626.17	8747.33	8400.17	6781.50	6398.00	6997.50	5572.50	9420.33	8214.00	6122.17	7488.00	9139.33

(May 1994 - Apr 1995)
Type of boats		No of boats	May	Jun	Jul	Agu	Sep	Oct	Nov	Dec	Jan	Feb	Mar	Apr
< 30 GT		1	9203.33	6805.50	8159.33	6314.50	7998.25	7814.33	7684.25	8190.00	8903.00	7984.00	8512.00	8110.20
30 - 50 GT		17	6150.52	6352.88	6342.48	6341.52	5870.10	6074.71	5941.96	6553.30	6116.72	7194.23	7164.28	6880.83
50 - 75 GT		2	7949.43	7927.50	9112.00	8748.50	8539.50	9156.00	9312.67	8318.67	8168.33	7543.33	9361.00	8021.67

(May 1996 - Apr 1997)
Type of boats	No of boats		May	Jun	Jul	Agu	Sep	Oct	Nov	Dec	Jan	Feb	Mar	Apr
< 30 GT	1		8240.00	10186.50	13575.00	11124.75	8571.33	11074.00	7122.33	3963.75	6736.50	5525.00	7177.00	6300.67
30 - 50 GT	10		7231.72	6167.44	8752.87	8438.83	7360.36	8955.79	7028.38	5508.52	6471.25	6245.44	5628.21	5436.35
75 - 100 GT	3		8685.50	9301.50	9961.80	10528.25	11180.17	7545.25	6610.25	4265.13	8572.33	4745.00	5320.00	5072.33
> 100 GT	5		9597.40	7581.00	10047.50	10478.60	11274.08	12056.27	9389.00	3749.36	4839.60	3285.42	3302.00	3482.09

(May 1997 - Apr 1998 )
Type of boats		No of boats	May	Jun	Jul	Agu	Sep	Oct	Nov	Dec	Jan	Feb	Mar	Apr
50 - 75 GT		5	11110.47	10798.02	10953.93	15511.87	12182.53	11526.25	12550.44	11182.29	6451.08	8072.98	8885.32	8562.92
75 - 100 GT		6	7514.23	15007.25	9300.70	11858.30	14965.24	14673.27	13810.72	13867.49	12570.85	13495.25	16484.78	15682.30

(May 1998 - Apr 1999)
Type of boats		No of boats	May	Jun	Jul	Agu	Sep	Oct	Nov	Dec	Jan	Feb	Mar	Apr
30 - 50 GT		2	9656.34	9599.23	8116.08	12545.53	13495.34	12659.99	11590.70	11141.43	8443.85	8176.65	8452.63	10930.82
50 - 75 GT		3	8294.37	7732.40	6344.10	10970.03	12185.11	7146.91	8531.31	8654.74	10574.82	9726.58	9516.99	8684.86
75 - 100 GT		1	14011.88	10698.33	17238.48	24622.25	25932.70	18415.60	17198.55	15055.90	10284.77	14589.75	15582.43	15550.50
> 100 GT		9	12316.22	11413.94	16318.48	17516.46	18209.48	15992.47	15020.56	14451.63	13458.45	12212.70	11181.05	13262.11

Table 2. Average of catch per unit effort (ton) for different types of boats from 1993 to 1999.

Type of boats	1993/1994	1994/1995	1996/1997	1997/1998	1998/1999
< 30 GT	7.20	8.01	8.30
30 - 50 GT	6.14	6.42	6.94		10.40
50 - 75 GT	7.58	8.51		10.65	9.03
75 – 100 GT			7.65	13.27	16.60
> 100 GT			7.42		14.28

Table 3. Monthly average of catch per unit effort (kg) of major species

in 1998 and 1999

Family	Indonesian Name	Scientific Name	1998	1999
Lutjanidae	1. Kakap Merah	Lutjanus sebae	54.5	61.0
	2. Jenaha	Lutjanus jonhi	70.6	80.3
	3. Kakap Merah	Lutjanus argentimaculatus	71.5	68.7
	4. Kakap Merah	Lutjanus biguttatus	75.0	92.6
Ariidae	5. Manyung	Arius thalassius	532.5	325.7
	6. Duri	Arius spp	55.5	84.6
Formiidae	7. Bawal Hitam	Formio niger	419.6	523.7
Pamphidae	8. Bawal putih	Pampus argenteus	199.5	118.2
Serranidae	9. Kerapu	Epirephelus merra	200.5	297.0
	10. Kerapu Lumpur	E. tauvina	492.4	504.7
	11. Kerampu macan	E. summana	265.3	99.7
	12. Kerampu Lumpur	E. malabaricus	504.9	445.7
	13. Sunu	Cephalapolis sp	115.7	154.9
Trichiuridae	14. Layur	Trichyurus savala	133.5	112.7
	15. Layur	T. haumela	95.6	120.7
Mullidae	16. Jenggot	Parupeneus spp	3320.0	2345.6
Synodonthidae	17. Beloso	Saurida undosquamis	54.0	73.2
	18. Beloso	S. tumbil	65.0	54.3
Polynemidae	19. Kuro	Eleutheronema pentarius	215.2	198.7
	20. Senangin	E. sextarius	315.9	517.8
	21. Kuro	E. tetradcctylum	443.2	423.9
Siganidae	22. Beronang	Siganuus Vermiculatus	99.7	85.4
	23. Beronang	S. javus	67.9	65.4
	24. Beronang	S. canalicilatus	125.3	75.6
	25. Beronang	S. spinus	204.5	327.4
Spyraenidae	26. Alu-alu	Spiraena langsar	213.7	267.5
	27. Alu-alu	S. jelo	287.8	342.6
	28. Alu-alu	Spiraena sp	75.9	105.7
Pomadasydae	29. Gerot-gerot	Pomadasys sp	989.0	765.5
Sciaenidae	30. Gulamah	Pseudoscienia spp	53.0	75.5
	31. Samgeh kuning	Johnius sp	87.0	99.2
Latidae	32. Kakap putih	Lates calcarifer	89.7	76.5
Nemipetridae	33. Koli	Nempiterus spp	10965.7	16956.6
Dasyatidae	34. Pari	Dasyatis spp	897.6	2876.5
Charcarhinidae	35. Cucut	Carcarinus spp	50.3	65.0
Carangidae	36. Selar	Selar bob	79.3	154.8
	37. Kuwe	Carangoides spp	987.9	564.7
	38. Bentong	Selar crumenopthalmus	145.5	128.7
	39. Kuwe	Caranx sp	675.9	987.5
Psetodidae	40. Ikan sebelah	Psetoides erumei	345.8	432.1
Penaeidae	41. Udang Windu	Penaeus monodon	464.8	376.9
	42. Udang Jerbung	P. merguiensis	97.9	165.5
	43. Udang Kerosok	Metapenaeus ensis	876.3	789.4
	44. Udang Doreng	Parapenaeopsis handwickii	324.9	298.7

Discussion

As shown in Table 3, most of the fish caught by the trawl during this study were demersal fish whose life is closely connected with the bottom of the sea. Major characteristics of the demersal fish group are : wide adaptability to the environment, forming relatively small schools compared to those of pelagic species, complex communities, low level of activity and small range migrations. Because of the last two characteristic, resistance to fishing pressure is weak. Consequently, when the intensity of fishing is doubled the pressure will tend to be doubled as well (Aoyama, 1973).

There were 110 species recorded during this study. This is a typically multispecies of demersal fish in a tropical region. Most species are caught in association with several others, often of lower value, which are usually discarded and therefore not recorded as production or when landed they are recorded as miscellaneous. Therefore the catch recorded in this study which were based on the landed fish may be lower than the real catch. However this may have little effect on the analysis of CPUE as an index of relative abundance.

Fishing activities for demersal resources in the Malacca Straits occur mainly in the shallow water. The stocks in this area are shared between Indonesia and Malaysia. Consequently, for a better estimation of their relative abundance, data should be gathered from the two countries. However, due to some limitations, and based on the assumption that demersal fish have a low level of activity and do not migrate very far, the analysis of CPUE, which is only based on the available data from the Indonesian part is assumed to be appropriate.

Table 2 shows that CPUE from May 1993 to April 1999 does not fluctuate much from year to year for boats of the same type.. The CPUEs within the period 1993 to 1999 do not tend to decrease. This indicates that the fish stocks in Malacca Straits still remain stable.

Table 3 shows that the CPUEs of the fishing fleet of less than 30 GT are relatively stable. These trawlers operated mainly close to the beach. .From 1993 to 1996 CPUEs of the fishing fleet of between 30 to 50 GT each group of trawlers were relatively constant. However, from 1996 to 1999 there was a significant increase of CPUE . On average the CPUE in 1999 was almost double of the CPUE in 1996.

For fishing fleet of 50 to 75 GT, the CPUE was relatively stable. This may due to the boat is too big to operate inshore, but too small to operate offshore. Within the last three years, the CPUEs of fishing fleet of more than 75 GT increase tremendously up to 200 %. This increase may due to the increase of catchability coefficient, a measure of the ability of the gear to catch fish (Sparre and Venema, 1992), as the results of using fish finder and more powerful engine. It may also due to the fishing fleet operated beyond the traditional fishing ground. The highest abundance of fish resources most likely occur in the water of 40 to 60 m depth.

Since the CPUE of large boats tend to be higher than those of smaller ones and they operated far offshore which may reduce conflicts with the smaller boats operating inshore, it is recommended in the long run that only this large fishing fleet are allowed to operate in the Exclusive Economic Zone.

Whatever the reason of the increase of CPUE, it may be concluded that there were no indicators of overfishing in this area. This conclusion was supported by the fact that the species composition of the catches in 1998 to 1999 were relatively constant (Table 3).

Refferences

Aoyama, T., 1973. The demersal fish stocks and fisheries of the South China Sea. SCS/DEV/73/3. FAO-UNO, Rome.

Aziz, K. A. , D. Die, N. Naamin dan B. Sumiono. 1997. Assessment of resources of penaeid shrimps in Indonesian waters. Venema, S.C. (ed.). Report on the Indonesia/FAO/DANIDA Workshop on the assessment of the potential of the marine fishery resources of Indonesia. FAO. Rome.

Aziz, K. A., M. Boer., J. Widodo, N. Naamin, dan A. Djamali. 1998 Potensi, Pemanfaatan dan Peluang Pengembangan Sumberdaya Ikan Laut di Perairan Indonesia. Pusat Kajian Sumberdaya Pesisir dan Lautan, IPB dan Komisi Nasional Pengkajian Sumberdaya Perikanan Laut. Jakarta.

Gulland, J. A., 1975. Manual of methods for fisheries resources survey and appraisal. Part 5. Objectives and basic methods. . FAO Fisheries Technical Paper no. 145. FAO, Rome

Gulland, J. A., 1983. Fish stock assessment: a manual of basic methods. Wiley Interscience, Chichester, U.K.

Sparre, P. and Venema, S.C., 1992. Introduction to tropical fish stock assessment. Part 1, Manual. FAO Fisheries Technical Paper No. 306, Rev. 1. FAO, Rome.

* A revised version of the paper presented at the Second International Conference on the Straits of Malacca, 15-18 October 2001. Penang, Malaysia.

Lutjanus sebae