Identifying mangrove areas for fisheries enhancement; population assessment in a patchy habitat

Abstract

1. Small-scale fisheries are an important element of the ecosystem goods and services that mangrove habitats provide, especially to poorer coastal communities that rely most on natural resources, and have similar values to payments for ecosystem services (PES) under carbon-trading schemes.2. In advance of fishery-enhancement trials for the mud crab Scylla olivacea, a mark-recapture study was conducted to estimate population size and turnover in 50 ha of isolated mangrove on Panay Island, Philippines. A total of 811 crabs were released in six sessions with an overall recapture rate of 41.5 AE 3.6%. Population size ranged from 607-1637 individuals.3. There was a high degree of site-fidelity, with 45.5% of recaptures in the same sampling areas as releases. Total mortality was 0.79 month -1 , with fishing mortality accounting for 95% of overall mortality. 4. Von Bertalanffy and Gompertz growth models yielded estimates for L 1 (carapace width) of 117.3 AE 14.7 and 110.6 AE 2.1 mm and for k of 2.16 AE 0.74 and 3.25 AE 0.81, respectively. Crab densities of 12-33 individuals ha -1 in the study area were lower than in other mangrove systems owing to intermittent recruitment, while growth rates indicated no limitation in terms of food supply.5. The study demonstrates that in specific mangrove habitats that are below carrying capacity, there is potential for fisheries enhancement to sustain or increase direct economic benefits from mangrove ecosystems and hence promote community engagement in broader conservation and PES initiatives.

Increasing productivity and improving livelihoods in aquatic agricultural systems: a review of interventions

“…Preliminary investigations demonstrate that restocking with juvenile mud crabs (Scylla olivacea and S. serrata) increases fishery productivity by 46%, from 48 ± 3 g per gear per day for wild crabs to 68 ± 3 g per gear per day for total wild and restocked crabs (Lebata et al 2009). Mean recapture rates range from 35-42%, highlighting the benefits of releasing juveniles for both long-term stock improvement (more than 50% of released crabs remain un-captured, although some likely suffer mortality) and seasonal improvement in fishery productivity (Lebata et al 2009;Lebata et al 2012).…”

“…Site selection for stock enhancement programs is also critical for insuring the success of the program (Lorenzen 2008). Lebata et al (2012) demonstrated that the Ibajay mangrove system in the Philippines was suitable for mud crab release because food supply and dietary composition were sufficient, as indicated by high specific growth rates of released crabs. The system was also relatively closed, which excluded predatory sharks and macaques, and the initial wild crab density was low (12-33 per crabs ha) compared to similar systems, demonstrating that the system was likely to be below carrying capacity and that the opportunity for stock enhancement was significant (Lebata et al 2012).…”

Kondisi Vegetasi Dan Perubahan Tutupan Lahan Ekosistem Mangrove Pulau Tanakeke Kabupaten Takalar Provinsi Sulawesi Selatan

“…Ekosistem mangrove memiliki produktivitas tinggi yang memperkaya kawasan pesisir, sehingga berpengaruh terhadap peningkatan produksi perikanan tangkap dan perikanan budidaya tambak tradisional (Gevana et al, 2015). Potensi ekosistem yang besar tersebut telah mengalami laju eksploitasi yang signifikan dengan memanfaatkannya tanpa memperhatikan aspek keberlanjutan ekosistem (Lebata et al, 2012). Menurut Fitri & Anwar (2014) Indonesia mengalami degradasi ekosistem mangrove pada 2 sampai 3 dekade ini sekitar 50%, dari luas total 6,7 juta ha dan sekarang tinggal ± 3,2 juta ha atau 22,6% luas mangrove dunia (Giri et al, 2011).…”

Analysis of mangrove forest vegetation in Wambona Village, South Wakorumba District, Muna Regency, Indonesia

“…Ekosistem mangrove berperan besar dalam menjaga keberlanjutan dan keseimbangan ekosistem pantai dan pesisir (Marchand, 2017;Nguyen & Parnell, 2017). Mengingat besarnya manfaat ekosistem hutan mangrove, terkadang pemanfaatannya tidak memperhatikan daya dukung lingkungan (Lebata et al, 2012) bagi keberlanjutan sumberdaya, baik secara biologis, fisik, ekologis maupun secara ekonomis (Rakhfid & Rochmady, 2013;Rochmady, 2015b). Aktivitas pemanfaatan berlebihan dapat menimbulkan dampak merugikan bagi masyarakat (Zaitunah, 2002;Agusrinal et al, 2015).…”