Capture Process Experiment Studies On Fish BehaviourIn Relation Net Transparency of Millennium Gillnet Operation In Bondet Waters, Cirebon
operation of 12 pieces gillnet and hauling process. For one day fishing trip, there were 2-3 times setting-hauling process, depends on the weather and current
condition. The catch number of millennium gillnet was dominated by threadfins
Polynemus spp. for 71.2871 of catch. While by-catch consists of striped catfish eel Plotosus lineatus, spotted catfish Arius maculatus, great barracuda
Sphyraena barracuda, triple tail Labotes surinamensis, barramundi Lates calcarifer, blue spotted snapper Lutjanus rivulatus, silver pomfret Pampus
argentus, stingray Dasyatis spp., garfish Hemirhampus spp. and shark Charcarinus spp..
The millennium gillnet, mostly caught threadfins. The slim and long-shape figure and lack of spines on its body makes this fish caught mostly caught on its
gill or caught on its maximum body girth and not to be entangled. There are some theories of how fish encountered gillnet. Some observe that
if a fish encounters a gillnet, it stops its movement temporarily but in shallow water , if the net swing because of waves and tilts to the front, the fish follows the
net and, when the net swings back, the fish get its head caught in a mesh of the net. Nomura, 1991.
Captured conditions depend greatly on the length size and struggling effort. The small fish, which body girth, were slightly smaller than the mesh perimeter
could penetrate the mesh by their head and become finally snagged or gilled. Meanwhile, the medium or large fish whose body girth exceeds the mesh size
could result into the complicated entanglement in the net by their violent struggling. This was happening also by fish that caught in sweeping trammel net
Purbayanto et al., 1999. Struggling effort usually caused injuries on fish body. Purbayanto 1999
described six patterns of damaged body of the dead Japanese whiting Sillago japonica caught by sweeping trammel net in Tateyama Bay, Japan. The patterns
are: 1 minor scale loss on the upper parts of the fish head in front of dorsal fin; 2 scar injuries and minor scale loss around the circumference of the maximum
body girth; 3 scale loss on several parts of the fish body; 4 moderate scale loss
49
on the fish body; 5 infections on the head and the fins being rotten; and 6 infections on the head, major fish body, and the fins being rotten.
Most threadfins caught in the experiment did not have any injuries on its body, but they have net-like shape mark caused by fish being gilled. Some fish
have minor scale loss on the upper parts of the fish head and scar injuries and minor scale loss around the circumference of the maximum body girth, the same
as first and second pattern of fish caught by sweeping trammel net. Since the fishes were in the good quality, with no injuries, most fishes sold
in the competitive price. Many of threadfins caught by this gillnet were export market oriented. They distributed this fish into Singapore and Malaysia.
The varieties of millennium gillnet target catch depends on the fish stock underwater and mostly influenced by fishing season. In west monsoon January-
February catch dominates by barred Spanish mackerel Scomberomorus spp. and frigate tuna Auxis thazard. This season concerning as the peak season of
millennium gillnet fishing. In east monsoon Juny-July sometimes barred Spanish mackerel and frigate tuna also get caught. In the monsoon betweens, the catch
dominated by threadfins. This explained why mostly gillnet catch in October- November was dominated by threadfins.
The multi-monofilament, the millennium gillnet material, has a very strong and flexible feature. Underwater, it could stretch and loose easily so then when the
fish entering the net, they easier to enter but difficult to escape. This material structure influencing the fish that caught by this gillnet. Probably because of this
reason, mostly fish caught without less of struggle and makes the fish has less injuries.
According of Stewart 1987 as cited by Ferno and Olsen 1994, the type of twine used in the net can, owing to differences in texture, influence the species
and the size range of fish caught. Comparative fishing experiments using twisted multifilament, monofilament and multi-mono nylon in loosely hung cod gillnets
produced very different size distributions of catches. The total of catch rates for the three net types were not very different, but as an example twisted
multifilament caught many smaller fish than monofilament. The most striking result of the investigations was the way that fish were caught in the three net types.
50
Stewart 1987 as cited by Ferno and Olsen 1994 indicated that these results were due to differences in texture between the used gillnet. With
monofilament, which is hard and stiff, cod were mainly gilled, while with multifilament, which is soft, cod were mainly tangled. With multi-mono, the
proportion of tangled and gilled cod were somewhere in between. Even though, mostly targeted species of this experiment mostly caught by gilled, the reason of
the texture of the material influencing the captured condition was considering reasonable.
From the result of behaviour experiment and capture process experiment that was conducted, it was revealed that the fish used in behaviour experiment was
a pelagic fish while mostly catch were dominated by demersal fish. This is important to discuss regarding of different types of fish pelagic or demersal has
different characteristics. The most consequential problem is the difference characteristics of visual acuity between pelagic and demersal fishes. Demersal fish
has not good visual acuity. Geonita 2004 described that the visual acuity of red snapper Lutjanus malabaricus is around 0.08-0.13 for the fish length of 100-185
mm. This statement indicates that waters in dark condition without enough light penetration and bad visibility will reduce the visual acuity of a fish. For the
pelagic fishes, for example frigate tuna Euthynnus affinis, the visual acuity is around 0.14-0.19 for the fish length of 285-375 mm. The clear condition of waters
and larger of fish’s length make frigate tuna has good visual acuity. In this experiment, the visual acuity of fish did not investigate through
histological experiment. But the fact that the field experiment caught mostly demersal fishes is an unexpected result. At first, some interview from the local
fishermen explained that the millennium gillnet is operates to catch pelagic species, such as barred Spanish mackerels, frigate tunas, sharks, and other types of
mackerels. But from the result of experimental fishing, demersal fishes dominate the catch. It means that the local fishermen operates this type of gillnet not only to
catch pelagic species but also demersal species. This situation makes another research regarding the demersal fishes behaviour is also need to investigate. This
is important to implement in order to understand the demersal fishes behaviour in relation to millennium gillnet.
51
REFERENCES
Ansharullah. 2004. Kemampuan Jaring Kejer dengan Jumlah Mata Berbeda dalam Menangkap Rajungan di Perairan Bondet, Cirebon: Pengaruh
Perbedaan Hanging Ratio 0.42;0.46; dan 0.5. Skripsi tidak dipublikasikan. Departemen Pemanfaatan Sumberdaya Perikanan, FPIK,
IPB, Bogor, hal 1-45.
Anthony PD. 1981. Visual Contrast Thresholds in The Cod Gadus morhua L. J Fish Biol 19:87-103.
Baranov FI. 1914. The Capture of Fish by Gillnets. Mater. Poznaniyu Russ. Rybolov., 36, 56-99. Partially translated from Russia by W.E. Ricker.
Baranov FI. 1976. Selected Works on Fishing Gear. Vol 1. Commercial Fishing Techniques Translated from Russian by Israel Prog. Sci. Transl..
Borgstrom. 1989. Direct Estimation of Gillnet Selectivity for Roach Rutilus rutiulus L in a Small Lake. Fish. Res.7:289-298.
Borgstrom R. 1992. Effect of Population Density on Gillnet Catchability in Four Allopatric Populations of Brown Trout Salmo trutta. Can. J. Fish. Aquat.
Sci. 49:1539-1545. Cui G, Wardle CS, Glass CW Johnstone ADF, and Mojsiewicz WR. 1991. Light
Level Thresholds for Visual Reaction of Mackerel, Scrombus scrombus L., to Coloured Monofilament Nylon Gillnet Material. J Fish Res 10:255-263.
Dickson W. 1989. Cod Gillnet Effectiveness Related to Local Abundance, Availability and Fish Movement. J Fis Res 7:127-148.
Ferno A, and Olsen S. 1994. Marine Fish Behaviour in Capture and Abundance Estimation. Oxford: Fishing News Books, p.134-165.
Firmansyah A. 2004. Kemampuan Jaring Kejer dengan Jumlah Mata Berbeda dalam Menangkap Rajungan di Perairan Bondet, Cirebon: Pengaruh
Perbedaan Hanging Ratio 0.44;0.46; dan 0.48. Skripsi tidak dipublikasikan. Departemen Pemanfaatan Sumberdaya Perikanan, FPIK,
IPB, Bogor, hal 1-43.
Fridman AJ. 1986. Calculations for Fishing Gear Designs. England: Fishing News Book Ltd, p.1-18
Geonita G. 2004. Ketajaman Penglihatan Kakap Merah dalam Kaitannya dengan Proses Penangkapan Menggunakan Pancing Ulur. Skripsi tidak
dipublikasikan. Bogor: Departemen Pemanfaatan Sumberdaya Perikanan. Fakultas Perikanan dan Ilmu Kelautan. Institut Pertanian Bogor. 41 hal.
53
Glass CW and Wardle CS. 1995. Studies on the Use of Visual Stimuli to Control Fish Escape from Code Ends. Part II. The Effect of a Black Tunnel on the
Reaction Behaviour of Fish in Otter Trawl Cod-ends. Fish. Res., 23:165- 174.
Glass CW, Wardle CS and Gosden SJ. 1993. Behavioural Studies of the Principles Underlying Mesh Penetration by Fish. ICES mar. Sci. Symp.
196: 92-97. Glass CW, Wardle CS, Gosden SJ, Racey DN. 1995. Studies on the Use of Visual
Stimuli to Control Fish Escape from Cod-ends. Part I. Laboratory Studies on the Effect of a Black Tunnel on Mesh Penetration. Fish. Res. 3:157-164.
Godo OR and Wespestad VG. 1993. Monitoring Changes in Abundance of Gadoids with Varying Availability to Trawl and Accoustic Surveys. ICES J.
Mar. Sci. 50: 39-51. Gray CA, Larsen RB, and Kenelly SJ. 2000. Use of Transparent Netting to
Improve Size Selectivity and Reduce Bycatch in Fish Seine Nets. Fish. Res. 45:155-166.
Gunarso W. 1985. Fish Behaviour in Relation of Gear, Method and Fishing Techniques. Bogor: IPB, Faculty of Fisheries and Marine Sciences, p.100-
106. in Indonesian Hamley JM. 1975. Review of Gillnet Selectivity. J Fis Res Bd Can 32:1943-1969.
Hayward RS, Margraf FJ, Knight CT, and Glomski DJ. 1989. Gear Bias in Field
Estimation of the Amount of Food Consumed by Fish. Can. J. Fish. Aquat. Sci. 46:874-876.
He P. 1991. Swimming Endurance of the Atlantic Cod, Gadus morhua L., at Low Temperatures. Fis. Res. 12:65-73.
Hovgard H and Lassen H. 2000. Manual Estimation of Selectivity for Gillnet and Longline Gears in Abundance Surveys. http:www.fao.orgdocrep005
x7788e x7788EOO.htmTOC [2
nd
February 2007]. Hylen A, and Jacobsen T. 1979. A Fishing Experiment with Multifilament,
Monofilament and Monotwine Gillnets in Lofoten during the Spawning Season of Arcto-Norwegian Cod in 1974. FiskDir Skr Ser HavUnders
16:531-550.
Jester DB. 1973. Variations in Catchability of Fishes with Color of Gillnets. Trans Am Fish Soc 102:109-115.
54
Legget WC, and Jones RA. 1971. Net Avoidance Behaviour in American Shad Alosa sapidissima as Observed by Ultrasonic Tracking Techniques. J Fis
Res Bd Can 28: 1167-1171. Muntz WRA. 1974. Comparative Aspects in Behavioural Studies of Vertebrate
Vision, in Comparative Physiology. Academic Press, New York. P.255-261. Nomura M. 1985. Fishing Techniques 3. Tokyo: JICA, p.35-44.
Nomura M. 1991. Fishing Techniques 4. Tokyo: JICA, p.16-23. Persson L. 1987. The Effect of Resource Availability and Distribution on Size
Class Interactions in Perch, Perca fluviatilis. Oikos 48: 148-160. Purbayanto A. 1999. Behavioral Studies for Improving Survival of Fish in Mesh
Selectivity of Sweeping Trammel Net Thesis of Doctoral Course. Tokyo: Tokyo University of Fisheries, p. 105-133.
Purbayanto A, Akiyama S, Arimoto T, and Sondita MFA. 1999. Capture Process of Sweeping Trammel Net with Special Reference on Operation Method and
Catch Pattern. Proceedings of The 3
rd
JSPS International Seminar on Fisheries Science in Tropical Area. Tokyo: TUF International JSPS Project
Volume 8, p.98-103. Purbayanto A, Imron M, and Surur M. 2007. Selektivitas Ukuran Udang Windu
pada Eksperimen Penangkapan dengan Trammel Net di Tambak. Perikanan Trammel Net: Analisis Selektivitas dan Fisiologis Tingkah Laku untuk
Kepentingan Pengelolaannya. Departemen Pemanfaatan Sumberdaya Perikanan, FPIK, IPB, hal 84-104.
Rengi P. 2002. Pengaruh Hanging Ratio terhadap Selektivitas Drift Gillnet: Experimental Fishing di Perairan Kab. Bengkalis, Riau. Thesis tidak
dipublikasikan. Program Pascasarjana, IPB, Bogor. Hal 1-56. Reppie E, and Lalamentik LTX.1999. Artisanal Fisheries in the Bunaken
National Park of North Sulawesi, Indonesia. Proceedings of The 3
rd
JSPS International Seminar on Fisheries Science in Tropical Area. Tokyo: TUF
International JSPS Project Volume 8, p.161-176. Rollefsen G. 1953. The Selectivity of Different Fishing Gear used in Lofoten. J.
Cons. Int. Explor. Mer 19:102-110. Rudstam LG, Magnusson JJ, Tonn WM. 1984. Size Selectivity of Passive Fishing
Gears: a Correction for Encounter Probability Applied to Gillnets. Can. J. Fish. Aquat. Sci. 41:1252-1255
Sainsbury JC. 1996. Commercial Fishing Methods: an Introduction to Vessels and Gears. 3
rd
edition. Oxford: Fishing News Books, p.238-255.
55
Sparre P and Venema SC. 1999. Introduksi Pengkajian Stok Ikan Tropis, Buku 1: Manual. Jakarta: Pusat Penelitian dan Pengembangan Perikanan. Badan
Penelitian dan Pengembangan Pertanian. Departemen Pertanian. 248 hal Stewart PAM. 1987. The Selectivity of Slackly Hung Cod Gillnets Constructed
from Three Different Types of Twine. J. Cons. Int. Explor. Mer 43: 189-193. Tweddle D and Bodington P. 1988. A Comparison of the Effectiveness of Black
and White Gillnets in Lake Malawi, Africa. J Fis Res 6: 257-269. Wardle CS. 1993. Fish Behaviour and Fishing Gear. In: Behaviour of Teleost
Fishes ed. T.J. Pitcher, Chapman and Hall, London. p.609-643. Wardle CS, Cui G, Mojsiewicz WR, and Glass CW. 1991. The Effect of Colour
Appearance of Monofilament Nylon Underwater. J Fis Res10:243-253. Washington P. 1973. Comparison of Salmon Catches in Mono and Multifilament
Gillnets. J Mar Fish Res 35:13-17. Yokota K, Purbayanto A, and Sondita MF. 2003. Selectivity of a Sweeping
Trammel Net for Banana Prawn in Pelabuhanratu Bay West Java. Jurnal Ilmu-ilmu Perairan dan Perikanan Indonesia Jilid 10 No. 1: 57-63.
56
Appendix 1 The map of experimental fishing operation
LEGEND
Fishing operation location
Fishing port Border of district or
province
Scale = 1 : 500.000
Cirebon Indian
Ocean Java sea
N
S W
E
JAVA SEA
INDRAMAYU REGENCY
KUNINGAN REGENCY
CENTRAL JAVA
Karangreja
Bandenga Citemu
Gebang Mekar
Ender
Bondet fishing port
Betoko Bungko Ijo
Fishing operation
CIREBON REGENCY
CIREBON Bondet
waters
E 108
P
o
P
30’ 109
P
o
P
N 6
o
30’
57
Appendix 2 The average length and body girth of Japanese Jack mackerels No
Length cm
Body girth cm
1 16 9
2 17 9
3 18 9
4 20 9.5 5 19 8.5
6 19.5 10
7 20.5 11
8 21 11
9 19 11
10 20 11
11 20 10.5 12 22 10.5
13 20 10.5 14 19 10.5
15 23 11.5 16 21
12 17 21
10 18 21
11 19 23.5
12 20 21
11 21 21.5
10 22 22 9.5
23 21 11
24 20 12
x±s.d. 20.25±1.72 10.46±0.1
58
Appendix 3 The average water temperature and salinity during experiment The average water temperature
Day of experiment
Temperature
o
C Salinity
ppm
1 19.200 1.028
2 19.100 1.028
3 19.100 1.030
4 19.200 1.030
5 19.200 1.030
6 19.300 1.030
7 19.100 1.030
8 19.100 1.030
9 19.200 1.030
10 19.100 1.030
Average 19.160 1.030
Sd 0.07
0.001
The average light intensity during experiment light intensitylux
Day of experiment
A B C D
1 181
285 187
282 2 352 185 308
228 3 227 314 298
278 4 182 259 191
315 5 201 287 171
294 6 263 167 263
271 7 183 173 300
234 8 319 168 263
276 9 251 198 301
276 10
283 183 296 273 Aver 244.20
221.90 257.80
272.70 total
average 249.15
Note: Test channel area
A B
C D
59
Appendix 4 Frequency and proportion of fish passing through the netting panel of contrast colour net panel
Frequency of fish passing through the netting panel Treatment of behaviour
Treatment of net colour
transparency Replicates
Voluntary Conditioned
1 2
3 2
31 27
85 11
10 Old white
x ± SE 20 ± 9.07
35 ± 24.84 1
2 3
1 5
10 10
Black painted
x ± SE 0.33 ± 0.33
8.330 ± 1.67 1
2 3
28 14
29 64
20 17
New white
x ± SE 23.67 ± 4.84 33.67±15.19
Control 123
276
Proportion of fish passing the mesh panel number of fishcontrol Treatment of behaviour
Treatment of net colour
transparency Replicates
Voluntary Conditioned
1 2
3 0.016
0.252 0.220
0.308 0.040
0.036 Old white
x
±SE
0.160 ± 0.070 0.128 ± 0.090
1 2
3 0.000
0.008 0.000
0.018 0.036
0.036 Black painted
x
±SE
0.003 ± 0.003 0.030 ± 0.006
1 2
3 0.228
0.114 0.236
0.232 0.072
0.062 New white
x
±SE
0.190 ± 0.040 0.122 ± 0.060
60
Appendix 5 Frequency and proportion of fish passing through the netting panel of behaviour experiment using specific white panels
Frequency of fish passing the netting panel Treatment
Replicates Control
Old white New white
White dyed
1 2
3 4
5 6
7 8
9 10
613 597
593 480
430 437
425 647
728 682
60 50
20 9
9 100
94 180
170 19
40 20
16 19
9 10
9 210
139 120
50 18
20 8
9 19
9 190
30 110
Proportion of fish passing the mesh panel number of fishcontrol Treatment
Replicates Old white
New white White dyed
1 2
3 4
5 6
7 8
9 10
0.098 0.084
0.034 0.019
0.021 0.229
0.221 0.278
0.234 0.028
0.065 0.034
0.027 0.040
0.021 0.023
0.021 0.325
0.191 0.176
0.082 0.030
0.034 0.017
0.021 0.043
0.021 0.294
0.041 0.161
61
Appendix 6 Statistical test of frequency of fish passing through the net Contrast Colour Panels: Result of Two Way Anova
Source of variation
Sum of squares