Single Bale-Bale Technology: Sustainable Utilization of Flying Fish Eggs in the Waters of the Aru Islands, Indonesia

The waters of Eastern Indonesia constitute a potential area for the utilization of flying fish eggs. The capture of fish eggs relies on the behavior of parent fish that deposit their eggs on floating objects at the sea surface. The technology is known by the name drifting FAD or its local name, “bale-bale”. However, the tendency of fishermen is to design double bale-bale for maximum utilization without considering the sustainability of the fishery resources. This research aims to develop single bale-bale technology for sustainable utilization of flying fish eggs in the waters of the Aru Islands, Indonesia. The vertical single bale-bale is an innovative system designed to enhance the efficiency of capturing flying fish eggs, reduce environmental impact, and support sustainable utilization. The research methodology involves the design and implementation of bale-bale, followed by performance evaluation and environmental impact analysis. The results of the study indicate that the vertical single bale-bale is more effective and sustainable compared to horizontal single bale-bale, mixed, or double configurations. Consequently, this research contributes to improving economic and ecological resilience while promoting environmentally friendly fishing practices.


Introduction
The waters of the Aru Islands in Maluku, Indonesia, are renowned for their shrimp resources [1,2,3] and abundant fish population [4,5,6].Among these resources is the Flying fish from the exocoetidae family [7].Flying fish eggs hold high economic value compared to the adult fish [8,9,10].Typically, these eggs are processed into luxury foods known worldwide as caviar [11,12] or tobiko [13,14].As a result, the production of flying fish eggs has become a crucial import commodity for countries that specialize in luxury food items [15,16].
The business of flying fish eggs represents a significant opportunity to enhance the well-being of the Indonesian community [17].However, on the flip side, if the utilization of flying fish eggs, which constitutes a living genetic resource [18], is not managed wisely, the sustainability of the fishery may face the risk of overfishing, as seen in the waters of the Makassar Strait and the Flores Sea [19,20].
Fishermen need to be guided towards environmentally friendly technologies [21] and oriented towards sustainable utilization [22].The flying fish egg-catching tool used by the general public is commonly known as a drifting fish aggregating devices/fads [23], but in reality, the rumpon is just an auxiliary fishing tool [24], while the rumpon used to collect flying fish eggs is a capture tool designed in such a way as to make the fish comfortable laying their eggs in it.The flying fish egg-catching tool

Early Field Survey
The research was conducted in the waters west of the Aru Islands, which is the operational area for bale-bale and the resting location for ships along the coasts of these small islands (Figure 1).On the west coast of the Aru Islands, the design of pattorani fishermen's bale-bale was surveyed directly, and the results of flying fish egg catches from 150 pattorani boats were recorded using structured interview methods with fishermen, captains, and boat owners.The findings were then verified with data from the Aru District Fisheries Service and the Dobo Harbor Master, as well as relevant literature studies.The implementation of this initial survey took place over five months from May to September 2022, which corresponds to the flying fish egg harvesting season in the waters of Maluku [26,27].The egg-catching tool used for flying fish is a single-designed homemade structure called "bale-bale," with a total of 35 units.The frame size is 1.2x0.1 meters, made of bamboo or floating wood.Bamboo or wood serves as the frame for the bale-bale, allowing it to float and remain at the water's surface.The attractor consists of coconut leaves that have been sun-dried for approximately 3 to 5 days.These coconut leaves are arranged into nine vertically stacked layers, with a total length of 90 cm.This differs from the attractors designed by Pattorani fishermen, which are horizontally arranged and consist of 11, 15, and 21 layers of coconut leaves, matching the bale-bale frame (Figure 2).The vertically or horizontally arranged coconut leaves serve as a place for fish to lay their eggs, utilized by parent fish that use floating objects [28].The upper/main PE multi-rope diameter is 6 mm, the branch PE multi-rope diameter is 5 mm, and there are 35 weights of 0.3 ounces each.The flag float uses a combination of cork, bamboo, and concrete.A 1.5 GT-sized boat serves as transportation for operating GPS as a navigation tool to determine the bale-bale capture operation points.Clip lights act as signal lights installed on both the boat and flag buoys (Figure 3).A camera is used for documentation during the research process.A laptop is used for organizing and processing research data.Writing tools are used to record all field data and information.A flashlight is used for illumination during operations, and a coat serves as protection during rain.
Furthermore, this design of the single vertical bale-bale is tested for a period of five months (from May to September 2023) concurrently with the flying fish egg harvesting season by pattorani fishermen using single horizontal bale-bale (30 boats), mixed (50 boats), and double (70 boats).

Data analysis
Analysis of efforts, production, and catch per unit effort (CPUE) is conducted to explain the utilization level of flying fish in the waters of the Aru Islands from 2015 to 2023 using polynomial regression analysis [29,30].Subsequently, the catch results of flying fish eggs and the impact of bale-bale utilization are assessed using descriptive analysis, with information presented in the form of images and tables [31], aided by Microsoft Excel software [32].

Efforts in capture, flying fish egg production, and annual CPUE trends.
The flying fish resources, specifically their eggs, have been utilized by Pattorani fishermen in the waters of the Aru Islands since 2009.However, the production and the number of vessels have been recorded from 2015 to the present (2023).The number of Pattorani vessels in the waters of the Aru Islands started with 10 fleets and has now reached approximately 180 units.About 150 vessels are based along the small islands in the western part of the Aru Islands, ranging from Warmar Island to Taberfane (Figure 1).The catch of flying fish eggs obtained from each vessel is then recorded, ranging from approximately 70 kg to 2000 kg per fishing season per vessel.The catch varies for each vessel depending on luck, the sea-going experience of each crew member, and the diverse designs of the bale-bale (Figure 2 and Figure 3).
The total production of flying fish eggs reported by the Fisheries Department of the Aru Islands and the number of vessels based on data from the Dobo Port Authority from 2015 to 2023 have been processed and presented in Figure 4. Based on Figure 4a, it is observed that the fishing effort, indicated by the number of Pattorani vessels operating in the waters of the Aru Islands, has increased each year, accompanied by a rise in the production of eggs, reaching its peak in 2020.Subsequently, from 2021 to 2023, the number of vessels tends to decrease, and the egg production remains stable during 2021-2022, while experiencing a significant decline in 2023.This phenomenon is suspected to be due to the addition of bale-bale units and dual designs implemented by fishermen since 2019.
Fishermen are modifying their bale-bale fishing gear to optimize the catch of flying fish eggs, unaware that the sustainability of flying fish eggs could be jeopardized in the following years.Based on Figure 4b, it is also evident that the CPUE (Catch Per Unit Effort) trend is decreasing each year.The analysis results show a significant relationship (p<0.05) in the form of a polynomial regression with a coefficient of determination (R2=0.934)with the equation: Y = 0.1956x2 -790.72x+ 799171, where Y is CPUE (tons/units) and X is the capture year.In general, it can be observed that CPUE from 2015-2016 tends to decrease, with a slight increase in 2017, a decrease again in 2018-2019, a rise in 2020-2022, followed by a decline in 2023.In detail, it is explained as follows: from 2015 to 2018, the production of flying fish eggs exceeded the number of vessels.Then, from 2019 to 2023, the number of vessels did not exceed the production because, on average, each vessel unit only produced about 650 kg/unit.This suggests that flying fish eggs in the waters of the Aru Islands have been overexploited.Despite the addition of vessels and bale-bale capacity, the catch did not show a significant increase; instead, it tended to decrease (Figure 4).Based on the analysis results in Figure 4, it is recommended that the utilization of flying fish eggs in the waters of the Aru Islands should be limited to a maximum of 407 tons.Meanwhile, the number of permitted operating vessels in the area is restricted to only 85 units.We predict that both values represent the Total Allowable Catch (TAC) if further analyzed.This is crucial as one of the solutions to ensure sustainable utilization of flying fish eggs.The suggestion to utilize fishery resources according to the TAC has been echoed by various researchers focusing on specific fish species, ranging from global waters [33,34] to Indonesia [35,36,37,38,39].Our study is limited to revealing the production of flying fish eggs, so further research is needed to assess the fishery resources, uncovering the potential value and the level of comprehensive utilization of flying fish resources.

The results include single, mixed, and double seat captures.
Next, the total catch results from Pattorani fishermen using different types of bale-bale are detailed monthly in Figure 5, and the daily per trip catch is presented in Figure 6.Based on Figure 5, it is observed that the catch results of Bale-bale tend to increase from June to August, followed by a decline in September.This indicates that the peak of flying fish egg captures in the waters of the Aru Islands is in July to August, with the presence of eggs in these waters for five months (May-September).Similar trends have been observed in flying fish resources in the waters Kei Islands [40], the Seram Sea [41,42], East Seram to Fakfak [43], and waters near Timor Leste [44].

Impact analysis of the utilization of bale-bale.
The total number of trial flights for capturing flying fish eggs was 68 trips, conducted over a five-month period for all designs bale-bale (see Figure 6).Furthermore, based on Table 1, it can be explained that the production of single vertical bale-bale units is 2.8 kg/unit, higher compared to mixed (2.7 kg/unit) and single horizontal (2.3 kg/unit), although lower than double designs (3.1 kg/unit), with standard deviations ranging from 1.139 to 1.396.These findings are expected to provide a solution for fishermen to regularly utilize flying fish eggs in the waters of the Kei Islands each year, as well as serve as fundamental information for policymakers in controlling the sustainable utilization of flying fish eggs.Table 1.Description of production for each unit of bale-bale along with supporting components.
Based on Table 1, although the catch of flying fish eggs is higher with double cages, in the long-term, the utilization of single vertical cages would be more advantageous due to its effectiveness in utilizing the number of coconut and bamboo leaves.Furthermore, we observed the flying fish parent trapped in all four tested bale-bale designs, and we suspect that the parent fish prefer attractors installed vertically because it facilitates their movement in and out of the layers while attaching their eggs to coconut leaves.This is supported by the absence of any parent fish on single vertical bale-bale, despite the considerable number of fish eggs adhering to those bale-bale.Conversely, horizontally positioned parent fish that exit late may get entangled with their own eggs due to the dense arrangement of coconut leaves, as evidenced by the number of parents simultaneously trapped in horizontal bale-bale.Similar observations were also made in the Seram Sea, Indonesia [45].Although this serves as a gateway for further research to meticulously examine the reproductive behavior of flying fish during egg-laying on various bale-bale, it necessitates support from underwater cameras for intensive observations during the bale-bale immersion period, approximately 20 to 22 hours.The total production of vertical cages is significantly low because only 35 units were used for testing this design, which is quite different from the other three designs (Table 1).If the same number of units is used, the results, ranked from highest to lowest, would be double cages, single vertical, mixed, and single horizontal cages, respectively.The calculation of long-term utilization of flying fish eggs is expected to be below the TAC, making it environmentally friendly due to the efficient and ecofriendly use of coconut and bamboo leaves.The findings of this research are also expected to serve as a basis for revising the flying fish egg fishing regulation based on the technical study of cages as a tool for catching flying fish eggs.

Conclusion
This research demonstrates that the use of single vertical cages is environmentally friendly and effective, with a capture yield of 2.8 kg per unit of flying fish eggs.It also involves the use of natural materials, namely coconut leaves and bamboo, which are efficient and sustainable.

Acknowledgement
We would like to express our gratitude to the Fisheries Department of the Aru Islands and the Harbor Master of Dobo for their significant contributions in providing annual data (2015-2023) on production and the number of pattorani boats.Special thanks also go to the flying fish egg fishermen and the field survey team who worked diligently during the two fishing seasons (2022-2023).This research was partially funded by the GEF 6 EAFM Project in Eastern Indonesia in collaboration with the Ministry of Maritime Affairs and Fisheries, Directorate General of Capture Fisheries, Indonesia.

Figure 1 .
Figure 1.The research was conducted in the waters of the Aru Islands, encompassing the resting locations of pattorani boats with single horizontal bale-bale designs, mixed designs, and double designs ( ).The study also covered the experimental area for operating vertical single bale-bale as well as the three bale-bale designs used by fishermen .

Figure 2 .
Figure 2. The design of Pattorani fishermen's bale-bale are as follows: a. Single horizontal, b.Mixed, c. Double, and d.Single vertical (development of single bale-bale).Legend: 1. Bale-bale frame, Top view made of buoyant bamboo or wood material, 2. Platform layer, Side view made of processed coconut leaves for 3-5 days, 3. Three-dimensional view of the bale-bale.

Figure 4 .
Figure 4.The relationship between the effort and flying fish egg production with the capture period (a), and the CPUE trend from 2015 to 2023 (b).Data source: The data has been processed from the Aru District Fisheries Office,and Harbor Master's Office in Dobo (2015-2023)

Figure 5 .
Figure 5. Catch results of Bale-bale based on the observation month.

Figure 6 .
Figure 6.Daily catch results of Bale-bale based on the fishing trip.