Pulau Tibi Merupakan Deretan Pulau-Pulau Yang Berada Di Provinsi Kalimantan Utara. Kalimantan Utara Merupakan Salah Satu Habitat Penghasil Kepiting Bakau Yang Potensial Di Indonesia. Faktor Lingkungan Baik Faktor Fisik Maupun Factor Kimia Dari Ekosistem Mangrove Di Pulau Tibi Mendukung Keberadaan Populasi Kepiting Bakau. Penelitian Ini Bertujuan Untuk Mengetahui Keragaman (Performance) Reproduksi Jenis Kepiting Bakau (Scylla Spp.) Di Kalimantan Utara Diperairan Pulau Tibi Melalui Pengamatan Aspek Reproduksi Yang Meliputi Tingkat Kematangan Gonad (TKG), Dan Hubungan Antara Lebar Karapas Dan Panjang Kerapas Dengan Berat Tubuh. Penelitian Ini Dilaksanakan Selama 2 Bulan Di Mulai Dari November Sampai Dengan Desember 2017. Pengambilan Sample Dilakukan Diperairan Pulau Tibi Kalimantan Utara Dan Sample Dianalisis Di Laboratorium Biologi Perikanan Fakultas Perikanan Dan Ilmu Kelautan, Universitas Borneo Tarakan. Dari Hasil Penelitian Variasi TKG Antara Jantan Dan Betina Yaitu, Jantan TKG I Sebanyak 28 Ekor (38,89%), TKG II Sebanyak 21 Ekor(29,17%), TKG III Sebanyak 17 Ekor (23,61%), TKG IV Sebanyak 6 Ekor (8,33%) Dan Betina TKG I Sebanyak 11 Ekor (19,30%), TKG II Sebanyak 20 Ekor (35,09%), TKG III Sebanyak 14 Ekor (24,56%), TKG IV Sebanyak 12 Ekor (21,05%). Dan Hasil Dari Analisis Terhadap Bobot Kepiting Bakau, Dibandingkan Bobot Berat Tubuh Berdasarkan Pada Bentuk Morfologi Gonad Maka Didapatkan Nilai IKG Yang Berkisar Antara IKG I Jantan 0,58 – 7,44 Dan Betina 2,49 – 10,10, IKG II Berkisaran Antara Jantan 2,21 – 6,86 Dan Betina 1,20 – 8,54, IKG III Berkisaran Antara Jantan 1.02 – 7.98 Dan Betina 1.94 – 13.26, IKG IV Berkisaran Antara Jantan 2.76 – 13.18 Dan Pada Betina Memiliki Kisaran 3.30 – 23.00.
Kata Kunci: Kalimantan Utara, Kematangan Gonad, Pulau Tibi, Scylla Spp

Tibi Island Is A Row Of Islands Located In North Kalimantan Province. North Borneo Is One Of The Areas Of Potential Mangrove Crab Income In Indonesia. Environmental Factors Both Physical Factors And Chemical Factors From Mangrove Ecosystems In Tibi Island Support The Presence Of Mangrove Crab Populations. The Aim Of This Research Is To Know The Reproduction Type (Reproduction) Type Of Mangrove Crab (Scylla Spp.) In North Kalimantan In Tibi Island Waters Through Observation Of Reproduction Aspect Including Maturity Level Of Gonad (TKG), And Relationship Between Carapace Width And Kerapas Length With Body Weight. The Study Was Conducted For 2 Months Starting From November To December 2017. Sampling Was Conducted In The Waters Of Tibi Island Of North Kalimantan And Samples Were Analyzed In Fisheries Biology Laboratory Of Fisheries And Marine Science Faculty, University Of Borneo Tarakan. From Result Of Research Of Variation Of TKG Between Male And Female That Is, Male TKG I Is 28 Tail (38,89%), TKG II 21 (29,17%), TKG III 17 (23,61%), TKG IV 6 (8.33%) And TKG I Female 11 (19.30%), TKG II 20 (35.09%), TKG III 14 (24.56%), TKG IV 12 Tails (21.05%). And The Result Of The Analysis On The Weight Of Mangrove Crab, Compared With Body Weight Weight Based On The Morphology Of Gonad, The IKG Value Ranges Between IKG I Male 0,58 - 7,44 And Female 2,49 - 10,10, IKG II Range Between Male 2.21 - 6.86 And Females 1.20 - 8.54, IKG III Ranges Between Male 1.02 - 7.98 And Female 1.94 - 13.26, IKG IV Ranges Between Male 2.76 To 13.18 And In Females Has A Range Of 3.30 - 23.00. Keywords: Gonad Maturity Level, Scylla Spp, North Borneo, Tibi Island