The relationship between total length and clasper length of scalloped hammerhead sharks caught from coastal fisheries in Eastern Indian Ocean.

Transcription

1 Some Biological Aspects of Scalloped in The Eastern Indian Ocean (Chodrijah, U & B. Setyadji) Clasper Length(cm) y=0.097x Total Length(cm) Figure 5. The relationship between total length and clasper length of scalloped hammerhead sharks caught from coastal fisheries in Eastern Indian Ocean. Discussion Length distribution of scalloped hammerhead in this study was cmtl, which has wider range of length size compared to White et al. (2006) in relatively same sampling location and in the southwestern equatorial of Atlantic Ocean (Hazin et al., 2001) in the southwestern equatorial of Atlantic Ocean which was cmtl and cmtl, respectively, with remarks that more juveniles were caught in this study. The mean size of both male and female sharks in 2013 decrease significantly compared to This could indicate the fishing pressure for this species was high and intensive. Most of the scalloped hammerhead sharks landed was immature (except for male sharks in 2010). The more immature shark caught the more vulnerable it populations in the future. Moreover scalloped hammerhead shark are known to have aggregating habit thus large schooling is vulnerable to fisheries (Baum et al., 2007). It also characterized with slow growth, lengthy gestation, long life, low productivity and has poorest ability to recover from increased mortality (Castro et al., 1999; Compagno, 1984; Last & Stevens, 1994, Smith, 1998). If more immatures were caught in the future the recruitment would be decreasing, and the rebound will take several years. According to Pitcher & Hart (1982), such condition will lead to unbalanced population and will trig growth overfishing. A condition where exploitation causes a lot juvenile caught before reaching their optimum growth. The proportion of female shark was significantly different against male both in 2010 and 2013, this result was higher compared to Hazin et al. (2001) in northeastern Brazil and Henderson et al. (2009) in Oman waters, but similar with Fahmi & Sumadhiharga (2007) in western Indonesia. The imbalance sex ratio between female and male was allegedly because adult female may occur at shallower water to give birth (Simpfendorfer, 1992). Juveniles and immature sharks are also known occupy shallow and coastal waters (Fahmi & Sumadhiharga). This condition might explain why more immature female was caught more frequent than male. According to White et al. (2008) the number of juvenile born by this shark is about pups with an average of 25 pups in the past 9-10 months, and the shark is viviparous with a yolk placenta (yolk-sac placenta). Despite having more pups compared to other species of sharks, the frequent exploitation could lead to declining of this species in the wild. The relationship between clasper length and total length was lineary positive where every 5 cmtl increment on clasper length adding 51 cmtl on total length. The relationship between those two variables were allegedly depended on clasper condition. The more calcium contained on the clasper, the shorter it will be. Relationship between the clasper length with total body length is usually used to determine the size at which the fish Elasmobranchii reach maturity (Stevens & McLoughlin, 1991). There are two parts of clasper on female shark but only one, which actually 95

2 Ind.Fish.Res.J. Vol.21 No.2 December 2015 : incorporated with cloaca during copulation. But some calcareous clasper that would make the length shrunk biased the data. In the future analysis the calcareous clasper should be separated with non-calcareous, in order to find more cohesive relationship between them. Based on this study, scalloped hammerhead shark is becoming a subject to overfishing especially in the eastern part of Indonesian waters where sharks fishing are more intensive in this particular area (White et al., 2006; Fahmi & Sumadhiharga, 2007; Kembaren et al., 2013). Substantially lower mean size and more immature sharks caught over years showed it. Many efforts have been done in order to reduce the catch and bring the population back in the wild. In the Indian Ocean, IOTC has come out with some resolution on this matter, namely Resolution 13/03, 13/06, 11/04 and 05/05. Those regulations concern on the obligation from the members to record, monitor, and report any activities related to sharks fisheries either as a target catch, by-catch or discard (retained or released). Based on the results of the 16th CoP to CITES (Convention on International Trade in Endangered Species of Wild Fauna and Flora) in March 2013, a group of kind hammerhead shark (Sphyrna spp) has been agreed to be included in Appendix 2 of CITES. Thus international trade in commodities hammerhead shark is limited and must follow the regulations of CITES. In accordance with the world concern, Indonesian Government through Ministry of Marine Affairs and Fisheries issued the Ministerial Regulation No. 59/PERMEN-KP/2014. This regulation strictly prohibits any activities related to transporting parts or whole of sharks, namely ocean whitetip shark (Carcharhinus longimanus), scalloped hammerhead shark (Sphyrna lewini), great hammerhead shark (Sphyrna mokarran) and smooth hammerhead shark (Sphyrna zygaena) to overseas. In order to monitoring the progress of such regulation, continuous efforts of data collection both landing data and scientific observer data are necessary. CONCLUSION Substantially lower mean size, more immature sharks and more frequent of female caught over years showed that scalloped hammerhead shark in the Eastern Indian Ocean are facing intensive fishing pressure which could lead to overfishing. This could harm the sustainability of scalloped hammerhead shark resource in the long run. The relationship between clasper length and total length was positively correlated where every 5 cmtl increment on clasper length adding 51 cmtl on total length. ACKNOWLEDGEMENTS This paper was a contribution of research activities on shark resources in the Indian Ocean South of Java Fisheries Management Area (FMA) 573 in 2010 and 2013, under the Research Institute for Marine Fisheries, Muara Baru, Jakarta. High appreciation is expressed to Dr. William White from ACIAR-CSIRO, Australia. REFERENCES Baum, J., S. Clarke, A. Domingo, M. Ducrocq, A.F. Lamónaca, N. Gaibor, R. Graham, S. Jorgensen, J.E. Kotas, E. Medina, J. Martinez-Ortiz, J. Monzini Taccone di J. Sitizano, M.R. Morales, S.S. Navarro, J.C. Pérez-Jiménez, C. Ruiz, W. Smith, S.V. Valenti & C.M. Vooren Sphyrna lewini. The IUCN Red List of Threatened Species. Version < Downloaded on 01 June Castro, J.I., C.M. Woodley & R.L. Brudeck A Preliminary Evaluation of the Status of Shark Species. FAO Fisheries Technical Paper No Rome: FAO. Clarke, S.C. 2004a. Shark Products Trade in Hong Kong and Mainland China and Implementation of the CITES Shark Listings. TRAFFIC East Asia, Hong Kong. Clarke, S.C. 2004b. Understanding pressures on fishery resources through trade statistics: a pilot study of four products in the Chinese dried seafood market. Fish and Fisheries. 5: Clarke, S.C., M.K. McAllister, E.J. Milner-Gulland, G.P. Kirkwood, C.G.J. Michielsens, D.J. Agnew, E.K. Pikitch, H. Nakano & M.S. Shivji Global estimates of shark catches using trade records from commercial markets. Ecology Letters. 9: doi: /j x. Compagno, L.J.V Sharks of the World. An Annotated and Illustrated Catalogue of Shark Species Known to Date. Part 2: Carcharhiniformes. FAO Fisheries Synopsis No 125, Vol. 4, Part 2. Rome: FAO. Effendie, M.I (In Indonesian). Fisheries Biology. Yayasan Pustaka Nusantara. Yogyakarta. 163 pp. 96

3 Some Biological Aspects of Scalloped in The Eastern Indian Ocean (Chodrijah, U & B. Setyadji) Fahmi & K. Sumadhiharga Size, sex and length at maturity of four common sharks caught from Western Indonesia. Mar. Res. Indonesia. 32 (1): 7-19 Hazin, F., A. Fischer & M. Broadhurst Aspect of reproductive biology of the scalloped hamm erhead shark, Sphyrna lewini, off northeastern Brazil. Environmental Biology of Fishes. 61: Henderson, A.C., J.L. McIlwain, H.S. Al-Oufi, S. Al- Sheile & N. Al-Abri Size distributions and sex ratios of sharks caught by Oman s artisanal fishery. African Journal of Marine Science. 31 (2): Kembaren, D.D., U. Chodrijah & A. Suman Size distribution and sex ratio of scalloped hammerhead sharks (Sphyrna lewini) in Indian Ocean at southern part of Java and Nusa Tenggara, Indonesia. Paper presented in IOTC 9th Working Party on Ecosystem and By-catch, October 2009, Mombasa, Kenya. 9 pp. IOTC (Indian Ocean Tuna Commission) Status of the Indian Ocean scalloped hammerhead shark. IOTC-2013-SC16-ES19. 6 pp. Last, P.R. & J.D. Stevens Sharks and Rays of Australia. CSIRO. Pp. 513 Maguire, J.J., Sissenwine, M., Csirke, J., Grainger, R. & S. Garcia. The state of world highly migratory, straddling and other high seas fishery resources and associated species. FAO Fisheries Technical Paper. No Rome: FAO. 84 pp. SEAFDEC (Southeast Fisheries Development Center) Report on the study of shark production, utilization and management in the ASEAN region Southeast Fisheries Development Center, Bangkok, Thailand. 299 pp. Simpfendorfer, C Biology of tiger sharks (Galeocerdo cuvier) caught by the Queensland shark meshing program off Townsville, Australia. Aust. J. Mar. Freshwater Res. 43: Smith, S.E., W.Au. David & C. Show Intrinsic rebound potentials of 26 species of Pacific sharks. Marine and Freshwater Research 49 (7): Stevens, J.D. & K.J. McLoughlin Distribution, size and sex composition, reproductive biology and diet of sharks from northern Australia. Australian Journal of Marine and Freshwater Research, 42 (2): DOI: /MF Sugiyono Nonparametric statistic for Research. Penerbit CV. Alfabeta, Bandung: vi White, W. T., P.R. Last, J.D. Stevens, G.K. Yearsley, Fahmi & Dharmadi Economically important sharks and rays of Indonesia. National Library of Australia Cataloging-in-Publication entry. Australia. 329 pp. White, W.T., C. Barton & I.C. Potier Catch composition and reproductive biology of Sphyrna lewini (Griffith & Smith) (Carcharhiniformes, Sphyrnidae) in Indonesian waters. Journal of Fish Biology. Vol 72, Issue 7, P onlibrary.wiley.com/downloaded in 19 June Pitcher, T.J & P.J.B. Hart Fisheries ecology. Croom Helm, London. 97

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5 Dynamics of Gears, Fleets, Catch and.in Labuhan Lombok, West Nusa Tenggara (Setyadji, B & B. Nugraha) DYNAMICS OF GEARS, FLEETS, CATCH AND FISHING SEASON OF SMALL- SCALE TUNA FISHERIES IN LABUHAN LOMBOK, WEST NUSA TENGGARA Bram Setyadji and Budi Nugraha Institute for Tuna Fisheries, Benoa, Bali Received; Mei Received in revised from November ; Accepted December bram.setyadji@gmail.com ABSTRACT In Indonesia, about 80% of fishing activities are small-scale and play major role both economically and socially. Previous studies mostly concentrated in Java, while in eastern part of Indonesia the information still scarce and limited. The study was conducted from January to December 2013, describes in detail the gears, fleets and catch dynamics of the small-scale tuna fisheries operating based in Labuhan Lombok Coastal Fishing Port (PPP. Labuhan Lombok). Small-scale tuna fishery in Labuhan Lombok are characterized by the small boats less than 10 GT, operating both troll line and hand line simultaneously, targeting large tuna, skipjack tuna and small tuna. Fishing season starts from April to August and influence by southwest monsoon wind and the presence of middleman as the connector between fishers and the market are the main character of the small-scale fisheries business in this area. KEYWORDS: Small-scale tuna fisheries, fishing gears, fishing season, Labuhan Lombok INTRODUCTION A universal definition for small-scale fisheries is not available, largely because of their complexity (Chuenpagdee et al., 2006), but common criteria (SEAFDEC, 2003) include: 1) operated and funded by local fishermen, 2) a predominance of small vessels (often <10 GT), 3) a predominance of traditional fishing gears (but may include trawl, seine, gill-net, and longline vessels), 4) fishing trips are generally short (1-14 days) and inshore (within the Indonesian Exclusive Economic Zones) and 5) some of the fisheries are subsistence fisheries, but most are commercial nowadays. Small-scale fisheries, especially in tropical coastal waters are characterized by great spatio-temporal variation, high diversity of gears and target species, wide dispersal of fishing activities along the coast, and uncertainty of landings (Oostenbrugge et al., 2002). In Indonesia, about 80% of fishing activities are small-scale (Mous et al., 2005) with various type of fishing gears (from traditional to modern technology) are used to exploit the fish resources (Sumiono, 1997). Regarding of its importance both economically and socially (Nikijuluw, 2002 after Wiyono et al., 2006), they are still poorly understood. Nusa Tenggara Barat is one of the examples for small-scale tuna fisheries in Indonesia. Its fleet is dominated by outboard motor (53.4%), non-powered boat (29.6%) and inboard motor < 5 GT (8.2%). Large pelagic fishes contributed up to 139,890 t during and the fisheries can lead to estimated production value up to IDR 1.5 trillion (DGCF, 2011). Corresponding author: Tuna Fisheries Research Station-Benoa Jl. Merta sari, No. 140 Banjar Suwung Kangin-Denpasar, Bali This number could not be ignored as it contributed a significant amount of earning to the society. Several studies of small scale tuna fisheries in Indonesia have been conducted i.e. Nurdin & Nugraha (2007) which focused on tuna hand line fisheries in Prigi, East Java, Faizah & Aisyah (2011) in Sendang Biru, East Java, and Sulistyaningsih et al. (2011) in Kedonganan Bali. Nurdin (2008) described small scale tuna fishery in Prigi, Trenggalek, East Java, while Muhammad & Barata (2012) reported the size structure of hand line catch around fish aggregating device (FADs) in south of Bali and Lombok. However, most of the previous studies were concentrated in Java and Bali, while the in Nusa Tenggara has not been fully described especially the structure and characterization of small-scale tuna fisheries in Labuhan Lombok, Nusa Tenggara Barat. The purpose of this study are to provide the dynamics of gears, fleets, catches and fishing season of small-scale tuna fisheries operating based in Labuhan Lombok, Nusa Tenggara Barat. Socio-economics perspective also added to the discussion. MATERIALS AND METHODS Study area PPP. Labuhan Lombok Coastal Fishing Port is located at 08 o 29 30"Sdan 116 o 38 35" E on the eastern coast of Lombok Island. The site was chosen because it is one representative of the Eastern Indonesia smallscale tuna fisheries. Labuhan Lombok is one of the biggest landing ports in East Lombok beside Tanjung Luar, and become one of the proposed locations for Tuna Revitalization Program in Nusa Tenggara Barat. 99

6 Ind.Fish.Res.J. Vol.21 No.2 December 2015 : Small scale fisheries characteristics are multi-gear and multi-species. In general, similar size fishing vessels operate various types of fishing gear on the same fishing grounds i.e. south of Lombok Island and Sumbawa Island, stretched from 9 12 o S and o E (Figure 1). Fishing vessels with gross tonnage (GT) < 10 are dominant used in this area with two major fishing gears used, i.e. troll line and hand line (with various modification on the design, hooks and baits). Figure 1. Known FADs of the small scale tuna fisheries based in PPP. Labuhan Lombok (actual FADs presumably higher). Sources of data and pre-processing Daily records from the local fisheries auction center of PPP. Labuhan Lombok from January to December 2013 provided a time series of small scale tuna commercial fishing data. Information on type and number of fishing gear (unit), number of fishing trip (trip year -1 ), and total weight (kg) of catches by species. This paper does not separate catch between troll line and hand line since both are used simultaneously during operation and the landing data were absent of information about catch per gear. The statistical data provided by PPP. Labuhan Lombok covered Fisheries Management Area 573 (Indian Ocean) and 713 (North of Nusa Tenggara and Banda Sea), prior to The data used for the analysis in this paper was restricted only from Indian Ocean (FMA 573) and limited to the fishes belong to the group of large tuna i.e. yellowfin tuna (Thunnus albacares), bigeye tuna (Thunnus obesus) and albacore (Thunnus alalunga); small tuna i.e. kawakawa (Euthynnus affinis) and longtail tuna (Thunnus tonggol); and skipjack tuna (Katsuwonus pelamis). Statistical data from processing plant (UD) Baura and local authorities also obtained (Dept. for the Supervision of Fishing Vessels/WASKI, Labuhan Lombok Coastal Fishing Port, and Harbormaster) as comparisons. Seasonal Fishing Index(SFI) Information on seasonal catch was gained by finding the average monthly data (production & effort) altogether of tuna (yellowfin & bigeye tuna), skipjack and kawakawa from 2002 to Highest value occurred was placed as a base for assumption for seasonal catch (Merta et al., 2004), following this equation: Average monthly production SFI = Average monthly production in general Where: SFI was Seasonal Fishing Index; RESULTS AND DISCUSSION Results Development of fleets and fishing gears Based on the fish carrier license (SIKPI) issued by transportation office (Dinas Perhubungan) there were only two type of vessels used in daily fishing operation, carrier vessel and the other is catcher/ troll line vessel (Figure 2). Both of them were under 10 GT, mostly between 3 4 GT (Table 1). Based on statistical data provided by PPP. Labuhan Lombok in 2011 there were 249 vessels registered, 16 enlisted as carrier vessel while the rest (233 units) were troll line vessels. The number of recorded landing vessel 100

7 Dynamics of Gears, Fleets, Catch and.in Labuhan Lombok, West Nusa Tenggara (Setyadji, B & B. Nugraha) from relatively stable, but in 2012 was rapidly decline (Table 2). The number fishing gear used between 2010 to 2012 also tend to decline during that period of the years. Carrier vessel does not equipped with fishing gears, it only collect fishes from local fishermen around the island, while troll line vessel equipped with troll line and hand line (multigears). Troll line and or hand line operation vessels rely on shallow water FAD, using 2 x 2 x 1 m Styrofoam as a buoy which attached to pieces of concrete as sinkers and utilizing coconut leaves as attractor (Appendix 1). Table 1. Materials Length (m) Width (m) Depth (m) Tonnage (GT) Capacity (ton) Crew Trip (days) Detail specification of troll line and hand line vessels (source: PPP. Labuhan Lombok) Details Specification Wood Table 2. The number of recorded landing vessel from (source: PPP. Labuhan Lombok) Gross Tonnage Year Up to 5 GT 1, > 5 10 GT 1,242 1,843 1,768 1,749 1,047 > GT > GT Figure 2. Carrier vessel (left) and catcher/ troll line vessel (right). Figure 3. The development of fishing gears from (source: PPP. Labuhan Lombok). 101

8 Ind.Fish.Res.J. Vol.21 No.2 December 2015 : Catches development During the period of this study, about 11 fish species were landed in PPP. Labuhan Lombok from troll line operation (with troll line and hand line gears), six of which are considered important: yellowfin tuna (Thunnus albacares), bigeye tuna (Thunnus obesus), albacore (Thunnus alalunga), kawakawa (Euthynnus affinis), longtail tuna (Thunnus tonggol), and skipjack (Katsuwonus pelamis) while the others like blue marlin (Makaira nigricans), black marlin (Istiompax indica), dolphinfish (Corryphaea hippurus) narrow-barred spanish mackerel (Scromberomorus commerson) and rainbow runner (Elagatis bipinnulata). Catch composition during January and December 2013 were dominated by yellowfin tuna (43.98%) and skipjack (28.76%) (Figure 7). Skipjack reached its peak on 2006 and declining afterward, adversely with yellowfin tuna, which progressing over years, while kawakawa relatively stable (Figure 8). Production of yellowfin tuna, skipjack and kawakawa are directly proportional with the number of the trip (Figure 9), it mean that almost all of the fleets are targeting for these commodities, while the other fishes listed i.e. dolphinfish, narrowbarred Spanish mackerel, billfishes etc. came as either by-catch or from carrier boat from local fishermen around the island using seine net. Figure 7. The average catches composition of troll line and or hand line from January to December Figure 8. Annual production of yellowfin tuna, skipjack and kawakawa from PPP. Labuhan Lombok between 2002 and