Ivana Yuniarti

The tidal flood that occurred in the coastal area of Indramayu in 2020 caused the farmers to fail the Vannamei shrimp harvest in Pabean Ilir Village. After the disaster, the farmers resumed their commodity with milkfish. To analyze if this strategy can compensate for the loss, it is essential to perform the feasibility and profitability of the new farming system. Water quality sampling, which referred to the standard method (APHA), was conducted at several sites in the pond. We elucidated the pattern of several water quality parameters such as water temperature, pH, salinity, dissolved oxygen, nitrite, nitrate, and ammonia, while the financial feasibility was assessed with a cost-benefit analysis. The data to conduct the analysis was collected by arriving series of structured face-to-face interviews and focus group discussions. A sensitivity analysis was carried out to measure the influence of changes in fish production and feed price. It is concluded that the water quality was suit...

The tidal flood that occurred in the coastal area of Indramayu in 2020 caused the farmers to fail the Vannamei shrimp harvest in Pabean Ilir Village. After the disaster, the farmers resumed their commodity with milkfish. To analyze if this strategy can compensate for the loss, it is essential to perform the feasibility and profitability of the new farming system. Water quality sampling, which referred to the standard method (APHA), was conducted at several sites in the pond. We elucidated the pattern of several water quality parameters such as water temperature, pH, salinity, dissolved oxygen, nitrite, nitrate, and ammonia, while the financial feasibility was assessed with a cost-benefit analysis. The data to conduct the analysis was collected by arriving series of structured face-to-face interviews and focus group discussions. A sensitivity analysis was carried out to measure the influence of changes in fish production and feed price. It is concluded that the water quality was suitable and safe for milkfish cultivation. We also noticed that the new aquaculture system was financially feasible, as indicated by the calculated net present value, benefit-cost ratio, and internal rate return.

Understanding appropriate governance arrangements for managing cage aquaculture systems in tropical lakes is essential, yet it is still overlooked by current studies. Here we discuss the lessons obtained from our interdisciplinary research (environmental–social science, ecology, and ecological economics) evaluating cage aquaculture management scenarios with the aim of facilitating sustainable cage aquaculture management in Lake Maninjau, Indonesia. The lessons we present are based on our analysis of why current management fails to achieve its goals of reduced cage aquaculture and improved water quality in the lake, despite the pres- ence of formal regulations for reaching these goals. The importance of understand- ing the social, ecological, and economic dimensions in designing management actions is highlighted. We discuss how our research framework embraces method- ological and epistemological differences between natural and social scientists to improve research integration and how it supports an adaptive research approach to studying (interventions in) complex ecosystems. We compare the relative advan- tages of our framework with well-established interdisciplinary conceptual and research frameworks revealing that it fulflls pertinent knowledge gaps through detailing the process of discipline integration, embracing epistemological plural- ism, and explicitly including the quantifcation of ecosystem-services trade-offs, uncertainties, and risks in the decision-making process. Finally, we use the lessons from applying our framework to propose a more integrated management action plan in the lake. We expect that the lessons in this research can be widely applied to other cage aquaculture management case studies and contribute to the development of inland water ecosystem management in Indonesia and other Global South Countries.

Physical cage aquaculture structure can attract native fish species in marine and freshwater ecosystems. Most studies on the effects of cage farms on native fish distribution have been undertaken in marine environments and outside of Asia as the main freshwater cage aquaculture producing region. Many studies have emphasised connections between native fish distribution and feeding time. Previous research also has shown the necessity to use modelling to monitor this effect to reduce data collection costs. Here we analyse the distribution of an endemic fish species, Rasbora manin- jau, and a native fish, Gobiopterus sp., associated with tilapia cage aquaculture occurrence using a Maximum Entropy Model (MaxEnt). We find that the application of the MaxEnt model can produce reliable and accurate information on the impacts of cage aqua- culture on the native fish species distribution aligning with the more expensive count data method. Our results also suggest that the species-specific interaction between the native fish and cage farms is mainly arising from an interaction between the ecological behaviour of the native fish with dimensions of the environmental condition such as turbidity. Our study therefore highlights the importance for improved appraisal of the ecology of native fish in the cage aquaculture risk assessment.

A Bayesian Belief Network, validated using past observational data, is applied to conceptualize the ecological response of Lake Maninjau, a tropical lake ecosystem in Indonesia, to tilapia cage farms operating on the lake and to quantify its impacts to assist decision making. The model captures ecosystem services trade-offs between cage farming and native fish loss. It is used to appraise options for lake management related to the minimization of the impacts of the cage farms. The constructed model overcomes difficulties with limited data availability to illustrate the complex physical and biogeochemical interactions contributing to triggering mass fish kills due to upwelling and the loss in the production of native fish related to the operation of cage farming. The model highlights existing information gaps in the research related to the management of the farms in the study area, which is applicable to other tropical lakes in general. Model results suggest that internal phosphorous loading (IPL) should be recognized as one of the primary targets of the deep eutrophic tropical lake restoration efforts. Theoretical and practical contributions of the model and model expansions are discussed. Short-and longer-term actions to contribute to a more sustainable management are recommended and include epilimnion aeration and sediment capping.

Physical cage aquaculture structure can attract native fish species
in marine and freshwater ecosystems. Most studies on the effects
of cage farms on native fish distribution have been undertaken
in marine environments and outside of Asia as the main freshwater
cage aquaculture producing region. Many studies have emphasised
connections between native fish distribution and feeding time.
Previous research also has shown the necessity to use modelling
to monitor this effect to reduce data collection costs. Here we
analyse the distribution of an endemic fish species, Rasbora manin-
jau, and a native fish, Gobiopterus sp., associated with tilapia cage
aquaculture occurrence using a Maximum Entropy Model (MaxEnt).
We find that the application of the MaxEnt model can produce
reliable and accurate information on the impacts of cage aqua-
culture on the native fish species distribution aligning with the
more expensive count data method. Our results also suggest that
the species-specific interaction between the native fish and cage
farms is mainly arising from an interaction between the ecological
behaviour of the native fish with dimensions of the environmental
condition such as turbidity. Our study therefore highlights the
importance for improved appraisal of the ecology of native fish
in the cage aquaculture risk assessment.

Grammoplites scaber which is observed are catched by hauled gear (seine nets, gill net) from Mayangan Coastal Waters, West Java ai .june-November 2003. Hermaphroditism is observed by histological method. Result of histology show that protandrous hermaphroditism is occnred in some of specimen. Fecundity is counted by gravimetric method. Fecundity of G. scaber does not have a strong relationship with total length and total weight of the fish.

Ternate merupakan sebuah pulau vulkanik di Maluku Utara, didalamnya terdapat gunung api aktif (G. Gamalama) berketinggian 1.715 m dpl. Di pulau ini terdapat tiga danau (Tolire Besar, Ngade dan Tolire Kecil) yang berdasarkan proses terbentuknya digolongkan sebagai danau vulkanik dengan type Maar. Pengukuran yang dilakukan di Danau Tolire Besar pada tahun 2011 menghasilkan informasi kondisi fisik danau dan daerah tangkapannya. Danau Tolire dikelilingi oleh tebing curam setinggi 60-80 m, tidak mempunyai outlet dan inlet hanya berupa alur air dari puncak Gunung. Luas DTA danau adalah 244,2 Ha dengan tanah ber-ordo Inceptisols dan Ultisols, dengan Iklim termasuk tipe iklim B (Basah). Kedalaman maksimum danau 43,1 m, diameter 600 m, luas badan air 26,5 Ha, kecerahan danau hanya 4 m, salinitas, DO serta profil pH dan ORP mempunyai pola yang hampir sama, yang mengindikasikan bahwa pada kedalaman antara 8 dan 9 m adalah lapisan chemocline atau oxycline. Lapisan permukaan cenderung bersifat o...

Mud crab (Scylla serrata) is one of the main bioresources which has important economic value in mangrove ecosystems. As a source of food, the crab is very popular and becomes one favorite food for most Indonesians. Currently its production mostly depends on capture activities. The declining of mud crab population has been reported in several places in the country. Some of the main problems causing the declining of mud crab production is degradation of its environment, uncontrolled mangrove area conversion into shrimp pond culture, and over fishing conditions. This research was conducted to develop the best silvofishery technique to boost mud crab production. The study site was Bingkar, Teluk Semanting Village in Berau District. It was conducted within two periods (May-June and September-October 2013). Mud crab was cultured using silvofishery pond combined with the cell system technique. There were 120 individuals categorized in to two groups of mud crab size (e.g. group A. 137±29 g ...

The environmental condition of Lake Maninjau, a complex tropical system in Indonesia, has been suffering from the proliferation of tilapia cage culture practices. The area around the lake is inhabited by the Minangese ethnic group, which has strong customary laws and clan system. Applying the Institutional Analysis and Development (IAD) framework and based on face-to-face semi-structured interviews, this paper aims to understand the challenges for the development of environmentally sustainable cage culture farming. Our institutional analysis reveals that the main challenges are low levels of trust between communities and officials, and conflicting formal and informal institutions which have prevented the emergence of strong rules-in-use. This is a particularly interesting theoretical contribution to the literature on the management of common pool resources (CPR), as our case study is an example of private property farming in a common pool resource (the lake), a dynamic which remains...

Mangrove area of Berau District, East Kalimantan Province is an important buffering zone for Derawan Islands. It also becomes a distinctive habitat for commercial fisheries commodity. Land conversion into shrimp ponds has threatened its sustainability. This paper summarizing its ecological condition, fisheries, and management options presents a guideline for the decision makers about what strategies can be applied in conserving the mangrove sustainability. Overall, the ecological condition is proven to support sustainable fisheries practice; such as shrimp and crab silvofisheries. Moreover, the calculation of firewood economic value shows that a sustainable commercial firewood production is another option that can be established to support local economic activities. In addition, a well managing ecotourism may be considered by local government considering its potential for local economic growth.

A blooming of Microcytis aeruginosa occurred in Maninjau Lake in 2000. Mass fish killed happened frequently due to deterioration of water quality in this lake. This study is aimed to observe the current environmental condition, fishery resources status and the state of development process of comanagement regime in Maninjau Lake. Water quality parameter such as temperature, conductivity, turbidity, pH and dissolved oxygen (DO) were measured in situ by using Horiba U-10 water checker. Total nitrogen, ammonia, nitrate, nitrite, total phosphorous, orthophosohate and chlorophyll-a parameter were analyzed using standard method. Phytoplankton was analyzed by Lackey Drop Microtransect. Fish samples were obtained from fishers’ catch. Fisheries data were collected by enumerator, through Focus Group Discussion (FGD), and questioner list methods. Stakeholder analysis was conducted by focus group interview and discussion. In general, water quality parameters were suitable for the life of aquatic...

Understanding appropriate governance arrangements for managing cage
aquaculture systems in tropical lakes is essential, yet it is still overlooked by current
studies. Here we discuss the lessons obtained from our interdisciplinary research
(environmental–social science, ecology, and ecological economics) evaluating cage
aquaculture management scenarios with the aim of facilitating sustainable cage
aquaculture management in Lake Maninjau, Indonesia. The lessons we present are
based on our analysis of why current management fails to achieve its goals of
reduced cage aquaculture and improved water quality in the lake, despite the pres-
ence of formal regulations for reaching these goals. The importance of understand-
ing the social, ecological, and economic dimensions in designing management
actions is highlighted. We discuss how our research framework embraces method-
ological and epistemological differences between natural and social scientists to
improve research integration and how it supports an adaptive research approach to
studying (interventions in) complex ecosystems. We compare the relative advan-
tages of our framework with well-established interdisciplinary conceptual and research frameworks revealing that it fulflls pertinent knowledge gaps through
detailing the process of discipline integration, embracing epistemological plural-
ism, and explicitly including the quantifcation of ecosystem-services trade-offs,
uncertainties, and risks in the decision-making process. Finally, we use the lessons
from applying our framework to propose a more integrated management action plan
in the lake. We expect that the lessons in this research can be widely applied to other
cage aquaculture management case studies and contribute to the development of
inland water ecosystem management in Indonesia and other Global South Countries.