Green Turtle Chelonia Mydas of Melaka and Negeri Sembilan
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Malayan Nature Journal 1993 46 : 243 — 253 The Status of the Hawksbill Eretmochelys imbricata and Green Turtle Chelonia mydas of Melaka and Negeri Sembilan JEANNE A. MORTIMER 1 , ZAID AHMAD 2 & SAFEE KASLAN2 Abstract : In this paper we present our assessment of the importance of the sea turtl e nesting and foraging habitats of the states of Melaka and Negeri Sembilan . Our studies done in 1990 and 1991 revealed that the population of the highly endangered hawksbil l turtle Eretmochelys imbricata nesting in the state of Melaka is in fact the largest i n Peninsular Malaysia . The duration of the breeding season was also established for the first time : it extends from February through September, and peaks during May, Jun e and July . In 1990, the Department of Fisheries and the state of Melaka, with assistanc e from WWF Malaysia, established a hatchery near Pengkalan Balak to which collector s sold their eggs during part of the 1990 and all of the 1991 nesting seasons . Of the 324 egg clutches recorded in 1991 (certainly an underestimate of the total actually laid) , 69% were deposited on mainland beaches between the northern border of Melaka an d Kem Terendak, 26% on Pulau Upeh, and 5% near Tanjung Kling . Further surveys are needed to confirm reports of important nesting activity on islands adjacent to Pula u Besar, especially Pulau Nangka. Our surveys and interviews indicate that significan t numbers of juvenile and adult hawksbill and green turtles Chelonia mydas inhabit foraging grounds in the Straits of Melaka . Conservation efforts must focus on preservation o f critical nesting and foraging habitat, complete protection of turtle eggs, and preventio n of accidental captures of turtles in fishing gear. We suggest that Pulau Upeh be designated a turtle nesting sanctuary . INTRODUCTION During the past four decades, scientists and resource managers in Malaysia have focused attention on the turtle populations of Terengganu, Saba h and Sarawak with emphasis on the leatherback Dermochelys coriacea and to a lesser degree on the green turtle Chelonia mydas (see review by Chan, 1991). Although hawksbill Eretmochelys imbricata populations throughout the country received little attention, we now know that the hawksbill i s one of the most endangered species of marine turtle in the world toda y (Carr & Meylan, 1980) . 1 Consultant, World Wide Fund for Nature (WWF) and Courtesy Assistant Professor, Zoology Department, University of Florida, Gainesville, Florida 32611, U .S.A. 2Jabatan Perikanan Negeri Sembilan/Melaka, Wisrna Persekutuan, Tingkat 9 , Jalan Hang Tuah, 75300 Melaka, Malaysia . (Accepted for publication 28 March 1993) 243 In recent years, through the efforts of the Malaysian Department o f Fisheries, the state governments, scientists at Universiti Pertanian Malaysi a and Universiti Malaya, and the World Wide Fund for Nature Malaysia (WWF Malaysia) we know significantly more about the status of turtles throughou t Malaysia, particularly the hawksbill . Current estimates of the numbers o f hawksbill egg clutches laid annually in each state are presented in Table 1 . More hawksbills nest in the state of Melaka than any-where else i n the Peninsula . Table IL Current estimates the numbers of hawksbill egg clutches lai d annually in each Malaysia e ihe, u are known to occur. Numbers o f Location Clutche s Source Laid Annually Turtle Islands Park, Sabah 350—400 Sabah Parks, unpubl . data ; (especially Pulau Gulisan) Phillipps, 198 8 Terengganu (especially 20—200 Fisheries Statistics, unpubl . ; Pulau Redang and Pulau Perhentian Mortimer, 1991c ; Chan, 199 1 Pahang (offshore islands) 100 Mortimer, 1991 a johor (offshore islands) 100—200 Fisheries Statistics, unpubl . ; Mortimer, 1991b ; Chan, 199 1 Kedah < 25 Sukarno, 199 1 Pulau Pinang < 25 Mortimer, 1991 d Perak (Pasir Panjang and < 25 Mortimer, 1990 ; Sembilan Islands) Fisheries Statistics, unpubl . Melaka > 350 This paper Kiew (1975) first recognized the need to protect the endangered hawksbills of Melaka, and identified Tanjung Kling, Pulau Upeh and Pulau Besar as important nesting sites. Chua (1979) reported the success of th e first artificial hatchery established in 1978 at . Tanjung Kling, Melaka . In July 1987, the Department of Fisheries of Melaka/Negeri Sembilan and th e state government of Melaka jointly established a hatchery on the island o f Pulau Besar located several kilometres offshore the town of Melak a (Mortimer, 1988) (Fig . 1) . There, 1320 eggs were incubated in 1987, 509 1 in 1988, and 2595 in 1989 . Unfortunately, eggs in the hatchery suffered a very low hatch rate, probably due to mortality incurred during transporta- tion of the eggs from the mainland nesting beaches to the island (Mortimer , 1989). In 1990, the Department of Fisheries and the state government o f Melaka, with partial funding from WWF Malaysia, established a new hatcher y on the mainland at Padang Kemunting near Pengkalan Balak, Melaka (Fig . 1) . 244 TG . DAHA N KG . HILI R • * 0 KUALA SUNOS' BAR U 0 *0 0 • • 0 TELO D BALANGA SUMATRA 0* 0 0 0 ••!••• T OK GON G * . NGEI TUAN G .0 *0 2'24'N - •• : PENGKALAN BALA K 00 KG . PADANG KEMUNTING (HATCHERY ) Figure 1 . Map showing locations of the turtle hatchery and major nesting areas of Melaka . Closed circles indicate the localities from which hawksbill turtle egg clutches wer e reportedly collected during the 1991 nesting season, Each closed circle represents on e egg clutch, Question mark (?) indicates areas in need of further surveys . Beginning in early June 1990, eggs collected on the mainland were plante d at Padang Kemum ing . Following is an account of the status and distribution of the marin e turtles in the states of Melaka and Negeri Sembilan based on informatio n gathered during operation of the hatchery in 1990 and 1991 and also fro m surveys conducted by personnel of the Department of Fisheries and WW F Malaysia. 245 METHOD S Compilation of Information on Turtle Nestin g All egg collectors were requested to sell the eggs they collected to th e Department of Fisheries for incubation in the hatcheries . During 1991 , the Department paid M$0 .50 per hawksbill egg (up from M$0 .30 per egg i n 1989) . For each egg clutch brought to the hatchery, the following record s were kept : the name of the egg collector, the date and time the eggs were removed from the natural nest, the location of the natural nest, and th e time the eggs were planted in the hatchery . (We also recorded : the number of eggs in the clutch, the incubation methods employed at the hatchery , the numbers of hat (tidings produced and the exact stages at which eg g mortality occurred in each nest . 'f hese data are discussed by Mortimer an d Zaid (1991, 1992), Mortimer et at, (1992) and Mortimer, Zaid & Safe e (MS in prep .) . ) In both 1990 and 1991, the nesting season was already under way when the hatchery began operation (in early June 1990, and in mid-Marc h 1991) . To determine hove any egg clutches had been laid during the firs t part of the 1991 season before the hatchery opened, personnel of th e Department of Fisheries extensively interviewed egg collectors in bot h Melaka and Negeri Sembilan . Turtles in the Offshore Waters of Melaka and Negeri Sembila n To determine the abundance of sea turtles in offshore waters, and th e extent to which they were purposefully or accidentally captured in fishin g gear, we interviewed fishermen and coastal residents . RESULTS AND DISCUSSION The Nesting Seaso n The data we gathered during 1991 are the first to define accurately the duration of the hawksbill nesting season in Melaka, and they demon- strate that the turtles nest during the months of February through Septembe r with a peak during the months of May through July (see Fig . 2b). Our records from the 1990 season are incomplete because data collection di d not commence until late in the season (see Fig. 2a) (Mortimer & Zaid, 1991 , 1992) . Earlier studies based largely on interviews with coastal residents ha d underestimated the length of the nesting season (Kiew, 1975 ; Chua, 1979). Geographic Distribution of Turtle Nesting In constrast to the well developed beaches of the east coast o f Peninsular Malaysia, mainland beaches of Melaka have narrow platform s composed of relatively fine-textured pyrogenic sand . The sand of the islan d beaches of Melaka ranges from igneous (e .g. on Pulau Upeh) to calcium 246 MELAKA HAWKSBILL NESTIN G 20 y- ‘:) )UGHT TO HATCHERY 1 a 0-111 71TII - 11 n 111 n Lli L i ll 1 T1 1 111111411111,11 ) JAN FE MAR APR MAY JUN JUL AUG SEP OCT 1990 AN FEB MAR A'R MTh' Jul JUL AU G 1 991 Figure 2 . Seasonal distribution of hawksbill turtle nestings recorded in 1990 (2a) an d 1991 (2b) . Note that during the 1990 season, no data were collected before 3 June an d after 28 August. 247 carbonate (e.g. on Pulau Besar) . Hawksbills typically lay their eggs at the rear of the beach under vegetation, often in a substrate comprising a mixture of sand and mud that is high in organic matter . Turtle nesting habitat at one time extended from the town of Melak a north to the state border . In recent years, however, much of the coastlin e between the town of Melaka and Tanjung Kling has been intensely developed and is no longer suitable for nesting turtles . South of the town of Melak a there is only mangrove . Table 2 shows the localities from which hawksbill egg clutches wer e reportedly collected during part of the 1990 (Mortimer & :aid, 1991, 1992 ) and all of the 1991 nesting seasons . The 324 clutches reported in 199 1 represent only the minimum number of clutches laid.