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KAJIAN ILMIAH IKAN GAR, FAMILI LEPISOSTEIDAE (Lepisosteus Spp. & Atractosteus Spp.): SPESIES ANCAMAN BAGI IKAN ASLI INDONESIA: Zoo Indonesia 2007

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KAJIAN ILMIAH IKAN GAR, FAMILI LEPISOSTEIDAE (Lepisosteus Spp. & Atractosteus Spp.): SPESIES ANCAMAN BAGI IKAN ASLI INDONESIA: Zoo Indonesia 2007 KAJIAN ILMIAH IKAN GAR, FAMILI LEPISOSTEIDAE (Lepisosteus spp. & Atractosteus spp.): SPESIES ANCAMAN BAGI IKAN ASLI INDONESIA: Zoo Indonesia 2007. 16(2): 87- 96 KAJIAN ILMIAH IKAN GAR, FAMILI LEPISOSTEIDAE (Lepisosteus spp. & Atractosteus spp.): SPESIES ANCAMAN BAGI IKAN ASLI INDONESIA Renny Kurnia Hadiaty Bidang Zoologi, Puslit Biologi-LIPI Jl. Raya Cibinong Km 46, Cibinong 16911 e-mail: [email protected] ABSTRAK Hadiaty, R.K. 2007. Kajian ilmiah ikan gar, Famili Lepisosteidae (Lepisosteus spp. & Atractosteus spp.): Spesies ancaman bagi ikan asli Indonesia. Zoo Indonesia 16 (2): 87-96. Indonesia dikenal sebagai negara yang memiliki diversitas ikan yang tinggi. Namun demikian masih banyak wilayah yang belum dieksplorasi, hingga masih banyak kemungkinan jenis baru ikan yang ditemukan. Di sisi lain, kerusakan lingkungan, peracunan serta introduksi ikan oleh pengusaha ikan sangat membahayakan kelangsungan hidup ikan asli Indonesia. Gar merupakan satu jenis ikan predator yang dilarang masuk ke Indonesia sejak tahun 1982, namun ternyata saat ini banyak yang membudidayakannya. Kajian ilmiah ikan gar dikemukakan antara lain: deskripsi, sejarah taksonomi serta biologinya, untuk menimbulkan kesadaran betapa berbahayanya ikan ini bagi ikan asli Indonesia. Kata kunci: Ikan gar, taksonomi, distribusi, habitat, biologi. ABSTRACT Hadiaty, R.K. 2007. Scientific review of Gars, Family Lepisosteidae (Lepisosteus spp. & Atractosteus spp.): threat species for native Indonesian fish . Zoo Indonesia 16 (2): 87-96. Indonesia is known as one of the countries with high fish diversity. There are a lot of unexplore area which possibly have some undescribe species. Damaging environment, poisoning and introduce species are very dangerous for the sustainability of the native fish species in Indonesia. Gars are the alient predator fish which prohibited to enter Indonesian waters since 1982, but the facts there are many breeders of this species. This review paper is to discus the description, taxonomical history and the biology of gars. The aim of this paper is to build the awareness on the dangerous and destructive of this fish for Indonesian native species. Keywords: Gars, taxonomy, distribution, habitat, biology. PENDAHULUAN taksonomi ikan di Indonesia masih bisa dihitung dengan jari. Indonesia dikenal sebagai salah satu negara yang mempunyai biodiversitas Banyaknya jenis-jenis ikan baru yang ikan yang tinggi, baik jenis ikan laut ditemukan di perairan tawar Indonesia ataupun tawar. Namun demikian dibuktikan oleh Kottelat & Whitten penelitian mengenai biodiversitas ikan (1996) yang menyatakan adanya 79 belum banyak dilakukan. Masih spesies baru ikan air tawar dalam banyak perairan tawar di Indonesia jangka waktu sekitar lima tahun. yang belum diteliti keragaman jenis Jumlah tersebut merupakan ikannya. Disisi lain, jumlah peneliti penambahan jenis ikan yang telah 87 KAJIAN ILMIAH IKAN GAR, FAMILI LEPISOSTEIDAE (Lepisosteus spp. & Atractosteus spp.): SPESIES ANCAMAN BAGI IKAN ASLI INDONESIA: Zoo Indonesia 2007. 16(2): 87- 96 diketahui sebelumnya (964 spesies) di dengan membuangnya ke sungai. Di wilayah perairan tawar Indonesia sungai Indonesia, ikan asal Amerika Bagian Barat dan Sulawesi yang Selatan yang tubuhnya ditutupi oleh dipublikasikan oleh Kotelat et.al semacam kulit keras tidak mempunyai (1993). Data ini belum termasuk predator. Sekalipun tidak bersifat wilayah perairan di Indonesia Bagian predator, namun jumlahnya yang kian Timur. Penelitian yang dilakukan di lama kian meningkat merupakan Wilayah Propinsi Papua dari 1995 kompetitor bagi ikan asli untuk sampai 1999 berhasil mendapatkan mendapatkan makanan ataupun 40 jenis baru ikan laut dan tawar ruang, sehingga lambat laun ikan (Allen & Renyaan 2000). sapu-sapu mendominasi perairan tersebut. Fenomena banyaknya wilayah yang belum tereksplorasi, sehingga Pada saat ini para pengusaha ikan kemungkinan besar masih banyak hias sedang demam membudidayakan jenis ikan yang belum diungkap jenis ikan lain, yang mempunyai sifat keberadaannya serta fakta predator hingga sangat ditemukannya berpuluh jenis baru membahayakan serta mengancam memerlukan perhatian kita untuk keberadaan ikan asli Indonesia. Ikan menjaga kelangsungan hidup ikan- tersebut dikenal dengan nama ikan ikan tersebut serta kelestarian gar. Gar adalah sejenis ikan primitif habitatnya. Namun ternyata seringkali yang merupakan turunan dari ikan- keadaan di lapangan sangat bertolak ikan paleoniscoids, yang mendominasi belakang dengan harapan. Banyak laut dan perairan tawar selama 200 perairan yang sudah tidak layak untuk juta tahun, yaitu dari pertengahan era kehidupan ikan karena lingkungan Devonian sampai era Mesozoic. Era yang rusak. Ada pula perairan yang Devonian adalah sekitar 400 sampai sangat bagus, sangat layak untuk dengan 225 MYBP (Helfman et al. kembang-biak ikan, namun tidak 1997). dihuni oleh ikan lagi, bahkan moluska ataupun krustasea pun tidak dijumpai, Di dunia ada tujuh spesies ikan gar, karena perairan ini sering diracun oleh namun di Indonesia dikenal dengan orang-orang yang tidak bertanggung nama ikan alligator atau alligator gar, jawab. Selain itu, para pengusaha ikan yang sebetulnya merupakan nama hias menambah masalah yang sudah populer dari satu jenis ikan gar. Di ada, yaitu dengan mendatangkan Indonesia, ikan gar ini merupakan satu ikan-ikan dari luar negeri (hias di antara tujuh jenis ikan berbahaya ataupun konsumsi) kemudian yang dilarang masuk ke wilayah dibudidaya tanpa memperhatikan perairan Indonesia, berdasarkan SK dampaknya bagi ikan asli Indonesia. Mentan 179/Kpts/Um/3/1982. Menteri Pertanian memutuskan untuk Satu contoh dampak negatif adalah melarang pemasukan jenis-jenis ikan dengan didatangkannya ikan sapu- berbahaya dari luar negeri ke dalam sapu (Liposarcus pardalis). Ikan ini wilayah Republik Indonesia. Amar semula dipelihara sebagai ikan hias, pertama yang harus dilakukan oleh sekaligus pembersih kaca akuarium. petugas karantina dilapangan apabila Dengan cepat jenis ikan ini merebut menjumpai ikan ini adalah hati penggemar ikan hias, memusnahkannya. Namun larangan pemeliharaannyapun mudah sehingga tersebut tampaknya tidak diindahkan, merebak di mana-mana. Namun bahkan ikan karnivor tersebut telah seiring dengan berjalannya waktu, merebak keberadaannya di Indonesia. orang mulai bosan, sementara ikan Hal yang sangat mengkhawatirkan sapu-sapu kian membesar hingga adalah karena ikan ini telah memasuki tidak lagi pantas menjadi ikan perairan umum, yang terakhir dijumpai akuarium. Cara termudah adalah di Jakarta bulan Februari 2007 lalu, 88 KAJIAN ILMIAH IKAN GAR, FAMILI LEPISOSTEIDAE (Lepisosteus spp. & Atractosteus spp.): SPESIES ANCAMAN BAGI IKAN ASLI INDONESIA: Zoo Indonesia 2007. 16(2): 87- 96 saat terjadi banjir besar (data tidak fakultatif. Hal inilah yang dipublikasi). memungkinkannya untuk dapat tetap bertahan hidup di perairan dengan Mengingat perlunya menjaga kadar oksigen yang sangat rendah. keanekaragaman jenis ikan asli Indonesia, dan masih banyak wilayah SEJARAH TAKSONOMI yang belum terjamah dan belum diketahui keanekaragaman jenisnya, Mengingat keberadaannya yang kasat perlu dikemukakan data-data ilmiah mata dan sangat menarik perhatian dan kemungkinan-kemungkinan yang dengan ukuran tubuhnya yang bisa ditimbulkan dengan keberadaan ikan mencapai tiga m dengan berat ratusan gar ini. Tujuan dari penulisan ini kilogram, taksonomi ikan gar telah adalah untuk meningkatkan melalui sejarah yang panjang. pengetahuan mengenai jenis ikan gar Sedikitnya ada 12 orang ahli taxonomi dalam rangka penanggulangan ikan yang telah mempelajari ikan gar penyebarannya. ini sejak tiga abad yang lalu, dengan sekitar 20 nama yang diberikan (Tabel DESKRIPSI 1). Ikan gar mudah dibedakan dari jenis Dari sederet nama genus (suku) lainnya dari moncongnya yang dalam Tabel 1, semula yang diterima panjang dengan gigi-gigi runcing di sebagai nama baku atau valid oleh rahang, serta dari sisik berbentuk para ahli taksonomi adalah intan yang tidak saling bertumpu. Ikan Lepisosteus Lacepede, 1803. Namun gar digolongkan dalam ikan primitif karena publikasi The phylogeny and karena dijumpai beberapa ciri ikan biogeography of fossil and recent gars primitif yaitu; oleh Wiley (1976), membagi gar 1. bersisik ganoid (rata-rata ikan menjadi dua suku, yaitu Lepisosteus yang hidup saat ini berisik stenoid dan Atractosteus. Para peneliti dan atau sikloid). juga kalangan praktisi di kebun 2. bentuk gelembung renangnya binatang, buku-buku ikan hias dan seperti paru-paru yang berguna para pemancing mengadopsi serta untuk membantu dalam menggunakan ke dua nama tersebut pernafasan. (http://en.wikipedia.org/wiki/Alligator_g 3. tulang ekor yang heterocercal ar). Sekalipun demikian, ada ahli ikan (namun dari luar nampak yang tetap beranggapan bahwa membulat). semua jenis ikan gar di dunia ini (Helfman et al. 1997; Page & Burr termasuk dalam suku Lepisosteus, di 1991). antaranya adalah Helfman et.al. (1997). Nelson (1994) menyatakan Bentuk tubuh ikan gar bulat bahwa famili Lepisosteidae terdiri dari memanjang seperti torpedo. Sirip dua genera, yaitu Lepisosteus (4 pungung dan sirip anal letaknya jauh spesies) dan Atractosteus (3 spesies). di bagian belakang tubuh. Sisiknya Wiley (1976) menyatakan bahwa suku tebal berbentuk wajik yang tidak saling Lepisosteus mempunyai ‘gill rakers’ bertumpu. Usus ikan gar mempunyai yang kecil, berbentuk buah pear katup spiral yang mengambarkan dengan jumlah 14-33; sedangkan sistem pencernaan primitif seperti Atractosteus mempunyai ‘gill rakers’ yang dijumpai di hiu. Ikan gar juga yang besar namun pipih,
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