Hazard Assessment and Risk Analysis of Reef Fish Stocks In Bintan Island Waters, Kepulauan Riau, Indonesia

MUHAMMAD ATHTHAAR N., Dr. R. Suharyadi, M.Sc.; Ir. B.G.C.M. (Bart) Krol, M.Sc.

2015 | Tesis | S2 Ilmu Lingkungan

Jumlah ikan yang dapat ditangkap dari suatu perairan berhubungan dengan tingkat produktifitas primer perairan tersebut. Dimana klorofil merupakan salah satu indikator dari produktifitas primer perairan. Ikan-ikan karang merupakan ikan ekonomis yang popular dan bernilai jual tinggi dan telah mengalami tanda-tanda overfishing. Teknologi penginderaan jauh memungkinkan pemantauan warna perairan secara berkelanjutan. Penelitian ini bermaksud untuk mengetahui hubungan antara dinamika produktifitas primer perairan di perairan Pulau Bintan dan tingkat produksi ikan karang. Suhu permukaan laut diperoleh menggunakan persamaan Brown dan Minnet (1999) dan klorofil diekstrasikan dengan rumusan O'Rielly et. al., (2000) dari citra MODIS level 1. Produktifitas primer perairan diestimasi menggunakan persamaan dari Behrenfeld dan Falkowski (1997) yang dikenal sebagai Vertical Generalized Production Model (VGPM), sedangkan tingkat produksi ikan karang mengacu kepada jumlah produksi yang diizinkan dari Kementerian Kelautan dan Perikanan. Dari hasil penelitian diperoleh bahwa selama kurun waktu 2005-2012 suhu permukaan laut cenderung stabil pada 30 derajat Celcius, dan kandungan klorofil berfluktuasi antara 2,0 hingga 3,4 mg/m3. Interpretasi warna perairan menunjukkan hasil yang cukup baik, secara umum, kandungan klorofil yang tinggi tercatat pada suhu optimum antara 25 dan 280C. Terdapat hubungan yang sangat kuat antara kandungan klorofil perairan dan nilai produktifitas primer, dimana nilai r2 adalah 0,86. Namun tidak terdapat hubungan antara kandungan klorofil dan suhu permukaan laut serta antara produktifitas primer dan suhu permukaan laut. Dalam rentang kurun waktu delapan tahun tidak terjadi gejala penurunan nilai produktifitas perairan antara 2005 dan 2012. Meskipun tidak terdapat hubungan antara produktifitas primer dan statistik produksi ikan karang, dari perbandingan data antara 2010 dan 2012 menunjukkan bahwa trend produksi ikan karang yang tinggi terjadi pada saat pertumbuhan produktifitas primer di perairan yaitu pada kwartal II dan kwartal III antara bulan April hingga September dalam setahun. Terkait dengan overfishing, telah terjadi over exploitation di wilayah penelitian dimana pertumbuhan unit kapal penangkap ikan perlu dibatasi untuk kelestarian spesies ikan karang.

The amount of fish that can be produced from water areas have a strong link with the primary productivity of the waters. Therefore, chlorophyll serves as one indicator of aquatic primary productivity. Reef fish species is a kind of fish that is very popular and has a fairly high selling value in the world and have experienced symptoms of overfishing. Remote sensing technology has been enabling continues monitoring ocean color properties. This study aim to find out the relationship between the dynamic of primary productivity in surrounding Bintan Island waters with the reef fish production. Sea surface temperature calculated using algorithm ATBD 25 from Brown & Minnett (1999) and chlorophyll concentration extracted with O'Reilly et al., (2000) formula from MODIS 1st level imagery. Vertical Generalized Production Model (VGPM), a model which developed based on chlorophyll concentration by Behrenfeld & Falkowski (1997), was applied to estimates primary productivity in the study area. Apart, quantifying on reef fish production were done based on Total Allowable Catch (TAC) from Ministry of Marine Affairs and Fisheries. Result shows that sea surface temperature within the study period tend to stable at 30 degree Celcius, whereas chlorophyll concentrations fluctuate widely within the same study period with highest concentration from 2,0 to 3,4 mg/m3. Measured ocean color properties shows relatively good performance, in general, highest chlorophyll concentration occurs at lower sea surface temperature lower between 25 and 28 Celsius degree. Statistics informed strength linear relation between sea chlorophyll and primary productivity, r-squared 0,86. There are no relationship between chlorophyll concentration and sea surface temperature as well as between primary productivity and sea surface temperature. Across eight years analysis on ocean color properties in area of study there is no indication about degradation of primary productivity from 2005 to 2012, in fact 2012 recorded the highest level of primary production. Despite having no real correlation between the estimated value of primary productivity and distribution of reef fish production, this study find out that a comparison of three years of data from 2010 to 2012, reef fish fisheries production increased rapidly in Q2 to Q3 in one year whereas primary productivity also increased in the same period. Related to over exploitation, allegedly aquatic habitat reef fish already saturated by the increase in fishing fleet units operating in the region, thus limiting the number of fishing unit is the recommended option.

Kata Kunci : Primary productivity, chlorophyll concentration, sea surface temperature, MODIS, VGPM, reef fish, Bintan, Kepulauan Riau