© 2002 Kiagus Abdul Aziz Posted: 10 January 2002

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.

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. From 1993 to 1996 CPUE of each group of trawlers were relatively constant. However, from 1996 to 1999 there was a significant increase of CPUE for each group of trawlers. On average the CPUE in 1999 was double of the CPUE in 1996.

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