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SEAFDEC/TD Page 2
Preliminary Report
Demersal Resources on the Untrawlable Grounds in the South China Sea and Andaman Sea
Nakaret Yasook and Somboon Siriraksophon SEAFDEC/Training Department/
Capture Fishery Technology Division/
P.O Box97, Phrasamut‐Chedi, Samutprakarn 10290 THAILAND
1. Introductions
The demersal fishery resources surveys on the continental slopes particularly in the un‐
trawlable grounds of South China Sea and the Andaman Sea have been conducting by SEAFDEC using the specific fishing gears such as bottom vertical longline or/and trap. The aim is to investigate the potential demersal resources existing on the continental slopes in the Southeast Asia waters through the actual fishing trials and data/information collection onboard the research vessels. This project is a part of ASEAN‐SEAFDEC program on the “Sustainable Utilization of Potential Fisheries Resources and Reduction of Post‐harvest Losses”. A series of field surveys were carried out with collaboration to SEAFDEC member countries.
2. Objectives
The main objectives are to collect basic data and information of the demersal fish species as well as to investigate the existing potential demersal fishery resources in the Southeast Asia Waters.
3. Materials and Methods
¾ Survey Periods and Area
Field surveys were carried out from 2004 ‐ 2007, Four survey areas covered in the un‐
trawlable area of SEAFDEC member countries namely 1) Andaman sea of Thailand, 2) West coast of Borneo in the Brunei Darussalam Waters Sabah and Sarawak of Malaysia, 3) West coast of Luzon and Sulu Sea of the Philippines, and 4) East coast of Vietnam (Fig. 1). A total of 105 fishing stations were carried out on board SEAFDEC research vessels namely MV SEAFDEC2.
¾ Sampling Gears: Bottom Vertical Longline
The bottom vertical longline was used for studying on distribution and abundance of the demersal species in the un‐trawlable areas. Fishing depths were set at between 38 and 300 meter.
Fishing operation was started in the early morning with 2 ‐ 4 hours immersion time. Number of hooks used was varied from 380 to 960 hooks up to the fishing ground. The squid was used as bait of all fishing operations. Construction of vertical longline gear is shown in Fig. 2.
Demersal Resources on Un‐trawlable Grounds [2007]
SEAFDEC/TD Page 3 Fig. 1 Bottom Vertical Longline fishing stations and all survey areas in years 2004 – 2007.
Fig. 2 The construction of Bottom Vertical Longline and its compositions that used in the survey.
SEAFDEC/TD Page 4 4. Results
¾ CPUE and Average Catch
Fig. 3 shows the CPUE in individual per 1000 hooks in each fishing stations. The highest CPUE was 384.72 Ind./1000 hooks found in Andaman Sea and the lowest CPUE was 1.19 Ind./1000 hooks in West coast of Borneo, Sarawak. Average CPUE in each survey areas and average composition of main catch; Serranidae, Lujanidae, Nemipteriae, economic fish, shark and ray and trash fish are shown in Fig. 4. Average catch in Andaman Sea was highest, 83.25 Ind./haul/1000 hooks. However, 50% was discard species such as shark and ray and trash fish.
Fig. 3 CPUE (Ind/1000 hooks) of Bottom Vertical Longline in each fishing station.
¾ Distribution and Abundance
Fig. 5, 6, and 7 show the distribution and abundance of Serranidae group, There are 19 species and one of unidentification specie of Serranidae distributed in survey area. Ephinephelus areonlatus (Areolate grouper) distributed in every areas. Fig. 8, 9, and 10 show the distribution and abundance of Lutjanidae group, 13 species and 2 of unidentification species of Lutjanidae distributed in survey area. Lipochilus carnolabrum (Tang’s snapper) was found in Andaman Sea and East coast of Vietnam only while Pristipomoides multidens (Goldbanded jobfish) was found in every areas. Distribution and abundance of Nemipteridae group was shown Fig. 11. Fig. 12 show distribution and abundance of shark and ray, Five families of shark were caught from bottom vertical longline. Squlidae (Dogfish sharks) was dominance in all areas.
Demersal Resources on Un‐trawlable Grounds [2007]
SEAFDEC/TD Page 5 Fig. 4 Average catch and group composition caught by Bottom Vertical Longline in each area.
Fig. 5 Distribution and abundance of Serranidae from bottom vertical longline.
SEAFDEC/TD Page 6 Fig. 6 Distribution and abundance of Serranidae from bottom vertical longline.
Fig. 7 Distribution and abundance of Serranidae from bottom vertical longline.
Demersal Resources on Un‐trawlable Grounds [2007]
SEAFDEC/TD Page 7 Fig. 8 Distribution and abundance of Lutjanidae from bottom vertical longline.
Fig. 9 Distribution and abundance of Lujanidae from bottom vertical longline.
SEAFDEC/TD Page 8 Fig. 10 Distribution and abundance of Lujanidae from bottom vertical longline.
Fig. 11 Distribution and abundance of Nemipteridae from bottom vertical longline.
Demersal Resources on Un‐trawlable Grounds [2007]
SEAFDEC/TD Page 9 Fig. 12 Distribution and abundance of sharks and rays from bottom vertical longline.
Table 1. Show the economic fishes caught from bottom vertical longline that categorized in the family that found in each survey area. The dominance family was different in each area such as the Cichlids fish (Cichlidae) was the highest family in Andaman Sea, 60.91 %, West coast of Borneo and West coast of Luzon and Sulu Sea were 56.69% and 69.13% of the Emperors fish (Lethrinidae), East coast of Vietnam was 41.92% of the Lizardfishes (Synodontidae).
Table 2. Show non‐target species caught by bottom vertical longline that categorized in family were found in each survey area. The prominent group was different for each area. The Gurnards, sea robins (Triglidae) was the highest family in Andaman Sea, 57.14%, West coast of Borneo was 77.57% of the Sharksuckers, West coast of Luzon and Sulu Sea were two prominent groups as 48%
of the Morays (Muraenidae) and 40% of the Threetooth puffer (Triodontidae), East coast of Vietnam was 41.09% of the Puffers.
5. Conclusions
Bottom vertical longline data shown that the high value of demersal fishery resources in untrawlable area of Southeast Asia Water especially groupers and snapper distributed in every survey areas. There are 20 species of groupers and 15 species of snappers were found but only some species such as Ephinephelus areonlatus distribute in every areas. The highest CPUE is in the Andaman Sea, followed by West coast of Borneo, East coast of Vietnam. The lowest is in the West coast of Luzon and Sulu Sea of the Philippines. There are about 50% of catch are discard include with shark and ray and the others non‐target species such as moray and puffer.
The fishery resources living in untrawlable fishing ground seem to be potential resources . However, the further studies are necessary in order to reduce the discard species.
SEAFDEC/TD Page 10 Table 1. The Individual catch/operation/1000 hooks of Economic fish in term of family group from Bottom Vertical Longline in each survey area
Survey Area Family Ind/operation/1000 hooks
Percentage
Andaman Sea Berycidae 1.38 0.60
Bothidae 9.44 4.12
Caesionidae 1.38 0.60
Cichlidae 139.35 60.91
Gempylidae 1.85 0.80
Haemulidae 18.51 8.09
Halocentridae 4.16 1.82
Hapalogenyidae 8.33 3.64
Lethrinidae 1.85 0.80
Priacanthidae 7.29 3.18
Sphyraenidae 1.38 0.60
West coast of Borneo Acropomatidae 5.20 3.56
Ariidae 3.57 2.44
Branchiostegidae 3.24 2.22
Carangidae 2.38 1.63
Haemulidae 1.38 0.95
Halocentridae 7.29 4.99
Lethrinidae 82.73 56.69
Sparidae 32.07 21.98
Scrombridae 1.19 0.81
Sphyraenidae 1.19 0.81
Synodontidae 5.65 3.87
West coast of Luzon and Sulu Sea Acropomatidae 1.04 2.06
Carangidae 11.91 23.66
Lethrinidae 34.82 69.13
Polymixiidae 1.04 2.06
Scrombridae 1.54 3.06
East coast of Vietnam Acropomatidae 1.08 0.76
Branchiostegidae 5.87 4.12
Carangidae 22.22 15.59
Coryphaenidae 1.38 0.97
Glaucosomatidae 12.15 8.52
Halocentridae 8.44 5.93
Sparidae 18.29 12.84
Priacanthidae 11.41 8.01
Terapontidae 1.85 1.29
Synodontidae 59.72 41.92
Demersal Resources on Un‐trawlable Grounds [2007]
SEAFDEC/TD Page 11 Table 2. The Individual catch/operation/1000 hooks of Trash fish in term of family group from Bottom Vertical Longline in each survey area
Survey Area Family Ind/operation/1000 hooks
Percentage
Andaman Sea Chaetodontidae 1.38 0.28
Dactylopteridae 1.38 0.28
Berycidae 24.40 4.93
Scorpaenidae 25.69 5.19
Echeneidae 4.62 0.93
Congridae 1.38 0.28
Muraenidae 150.38 30.39
Triglidae 282.75 57.14
Tetraodontidae 1.38 0.28
Triodontidae 1.38 0.28
West coast of Borneo Monacanthidae 1.38 1.49
Scaridae 1.38 1.49
Labridae 1.22 1.31
Scorpaenidae 1.22 1.31
Echeneidae 71.93 77.57
Ophichthidae 1.19 1.28
Muraenidae 1.04 1.12
Ostraciidae 1.38 1.49
Tetraodontidae 2.61 2.81
Diodontidae 4.09 4.41
Triodontidae 5.24 5.66
West coast of Luzon and Sulu Sea Labridae 1.04 12
Muraenidae 4.16 48
Triodontidae 3.47 40
East coast of Vietnam Dactylopteridae 1.85 0.64
Berycidae 8.18 2.87
Echeneidae 2.77 0.97
Ophichthidae 6.82 2.39
Congridae 38.88 13.63
Muraenidae 103.51 36.29
Ostraciidae 2.22 0.77
Tetraodontidae 117.19 41.09
Triodontidae 3.70 1.29
6. Acknowledges
The authors highly appreciated to all crew and Captain of MV SEAFDEC2 for their support on data collection based fishing trails.
