Catching Dory: selling aquarium fish supports coastal livelihoods in Indonesia

Abstract

The global marine aquarium trade has created new local markets across the planet, including in Indonesia, now the second-largest exporting country of marine aquarium fish in the world. Participating in the global aquarium trade has been touted as a potentially sustainable addition to fisher livelihoods, but scant data exist showing the numbers of fish coming off the reef and how those fish contribute to income. To determine how participants in the trade incorporate aquarium species in their livelihoods, we examine source-level aquarium fish collecting and trading data in the Banggai Archipelago, a region in Central Sulawesi that has become a significant source for popular aquarium, also known as ornamental, fish species. Using a sustainable livelihoods lens, we examine this data to understand how participants in the aquarium trade both contribute to as well as benefit from the trade and consider how their participation relates to emerging Blue Justice principles. From one year of buying and selling data at the fisher, intermediary buyer, and regional trader levels, we show that catching and selling fish for the aquarium trade represents an average of nearly 20% of their gross annual income and provides added diversity and flexibility to fisher and trader livelihoods in the region, especially during seasons of rough weather. We suggest that managers of an impending marine protected area in the region would do well to consider how to sustain these livelihood benefits.

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Introduction

Keeping aquarium fish, one of the world's most popular hobbies, is supported by a global trade that moves more live animals across the planet per year than any other industry^1,2. The trade involves more than 2 million people, from collectors at source sites in export countries, to public aquaria and hobbyists with home tanks in import countries^1,3. Generating an estimated $15–20 billion in revenue per year¹, this industry has created a constellation of local markets across the globe, often in remote rural, coastal, and island communities.

Due to the dispersed nature of the aquarium trade that often creates opaque supply chains, it is not well-quantified or regulated⁴. This is especially true in the marine aquarium trade (MAT), which involves over 2300 different marine species⁵. Although freshwater aquarium species are mostly captive-reared, marine fish have complex breeding cycles and larval development, which make them difficult to culture, and so are primarily wild-caught^6,7,8,9.

Catching fish from tropical coral reefs around the globe^6,10,11,12, small-scale fishers have been the primary procurers of marine aquarium, or ornamental, species^6,13, this is especially true in the Indo-Western Pacific^4,13,14. These individuals who participate in the sourcing side of the trade, are an oft-overlooked part of a larger global population working in small-scale fisheries, which employ over 100 million people¹⁵—more than the other largest ocean sectors combined^16,17,18.

Over the past two decades, the importance of small-scale fisheries has been increasingly acknowledged through growing attention from researchers^15,16,19 as well as national and international non-governmental organizations (NGOs) and government agencies²⁰. With this increased attention, a "Blue Justice" focus has emerged that calls for formally recognizing the rights and economic contributions of small-scale fishers^21,22. This focus is evidenced at the international level by Sustainable Development Goal 14, which addresses ocean conservation and includes language describing the need to protect the rights and livelihoods of fishers and fishworkers²⁰.

However, relatively little is known about small-scale fisher livelihoods generally²³, and especially those involved in the MAT^6,24, making it difficult to document their economic contributions and distinct lifeways to help realize Blue Justice principles. This lack of knowledge regarding small-scale fisher livelihoods occurs in part because small-scale fisheries are diverse and decentralized^16,25,26. Moreover, they often operate in informal spaces beyond the reach of government monitoring and oversight²⁷. This opacity increases when small-scale fishers employ illegal fishing methods that require discretion, like using cyanide to stun and catch aquarium fish for the MAT.

These factors, among others, have led to the current state of the MAT in which, although some comprehensive data sets are available at the export/import level (see Rhyne et al.⁵), few data are available quantifying the "ground zero" harvesting level⁴. These source-level data are critical to better managing the MAT⁴ in two ways: 1) to better understand the number of fish taken off reefs, as export numbers do not include domestic trade or mortality prior to leaving the source country; and 2) to understand the trade's contribution to small-scale fisher and buyer livelihoods and well-being.

We address this knowledge gap by examining source-level catch and trade data from the Republic of Indonesia. In addition to being the second largest exporter of marine aquarium fish⁵, Indonesia is part of Asia where, despite being home to the largest number of small-scale fishers in the world, the human dimensions as well as community and ecosystem ecology of small-scale fisheries are understudied²⁸. Indonesia also has the fourth-largest population in the world, including numerous under-resourced communities that target marine aquarium species^6,29. Within Indonesia, we examine the MAT in the Banggai Archipelago, in the province of Central Sulawesi. This archipelago is one of several groups of small islands in the seas around Sulawesi, the fourth largest island in Indonesia³⁰. Even some of the most comprehensive and recent data on the MAT in Indonesia lack data from Central Sulawesi (cf., Akmal et al.⁸). This paucity of MAT information exists though the Banggai archipelago is at the heart of the Wallacea and Coral Triangle biodiversity hotspots³¹ and is a known source for the MAT³².

The data we present are timely, as a newly legislated marine protected area (MPA) in the region may affect the livelihoods of fishers who target marine aquarium fish once the MPA becomes operational. This impending MPA may infringe on the rights of fishers and fish workers participating in the MAT in this region, as outlined by specific formulations of "Blue Justice" that focus on aspects of spatial justice³³ like dispossession and displacement³⁴, as well as lost access to marine resources needed to support well-being³⁴.

We examine the data using a social-ecological systems framework^35,36 and applying a sustainable livelihoods lens^37,38 that seeks to understand ways in which fishers build resilience to the uncertain ecological, economic, and political disturbances they often face³⁹. Drawing on this theory and relating it to the emergent concept of Blue Justice, we ask whether and how fishers and fishworkers in the Banggai Archipelago contribute to the global MAT, as well as the inverse: whether and how does the trade contribute to their livelihoods and broader well-being?

Results

Size and structure of the fishery

Fish species traded and fishing methods

A total of 74,122 individual fish were caught and traded across 1042 distinct transactions during the period of data collection spanning October 2018 to October 2019. Considering that total marine aquarium fish exports from Indonesia in 2018 were estimated at 2.61 million individuals⁴⁰, our findings represent nearly 3% (~2.84%) of total Indonesian exports. The aquarium fish species primarily traded included blue tang (Paracanthurus hepatus), comprising 20% of the fish traded (14,852 individuals) and yellow goby (Gobiodon okinawae), comprising 80% of the fish traded (59,270 individuals). Nine Napoleon wrasse (Cheilinus undulatus) were also traded but we exclude them from the totals due to their small numbers. Because blue tangs have a higher value, fish of that species comprised 87% of total revenue, whereas the yellow goby (higher in overall number in this sample) only comprised 13% of total revenue (see Fig. 1). Prior to the collection of the data used in this study, researchers and conservationists working in the region were unaware that the lower value, but more abundant and easily caught, yellow goby was being sold from the area⁴¹. Respondents recorded all blue tang as being caught by a small net, although participant observation and interviews revealed that the use of cyanide, referred to locally as "potas," or another neurotoxin, referred to as "bius," was frequently used to stun the fish to make them easier to catch. Whereas respondents reported that yellow goby were caught using a scoop net with a handle called a "serok" without the aid of neurotoxins. Additionally, spearfishers, who had hookah and compressor diving equipment, would often collect blue tang incidentally, when they spotted them while out fishing for other target species (e.g., octopus, squid, snapper, grouper), only occasionally making trips to target them; whereas, fishers nearly always made trips specifically to collect yellow goby.

**Fig. 1: Comparing total volume and revenue of fish sold by species.**

Fisher-buyer-trader network

We identified a network of fishers, buyers, and traders that included 111 people (see Figs. 2 and 3 below), of whom 108 resided in the source village. These people involved in the aquarium trade represent 5.8% of the source village population, which was 1855 individuals according to official statistics⁴² and an estimated 29% of households using an average of five people per household⁴³. The network includes a total of 98 individual fishers who caught and sold fish; 9 intermediary buyers, who purchased fish from individual fishers and then sold the fish to regional traders; and four regional traders who bought both directly from fishers and from intermediary buyers. This network underestimates the number of total fishers involved in the trade, as presumably the buyers who sell to Trader 2 whose data we did not collect, are purchasing fish from individual fishers, and we were unable to collect data from Traders 3 and 4.

**Fig. 2: Social Network Analaysis (SNA) showing trade structure, relative revenue share, & frequency of transactions in the fisher-buyer-trader network in Banggai.**

**Fig. 3: Social Network Analaysis (SNA) showing trade structure, relative revenue share, & frequency of transactions in the fisher-buyer-trader network in Banggai with static ego nodes.**

In addition to showing the general structure of the aquarium trade network (see explanation of Figs. 2 and 3 in captions below), our Social Network Analysis (SNA) also revealed a wide range of catching, buying, and selling frequency across fishery participants. The four respondents bought and sold fish frequently, with Trader 1 and Trader 2 buying or selling fish an average of every 2.6 days, Buyer 1 every 1.8 days, and Buyer 2 every 1.5 days. Numerous fishers also participated frequently, as denoted by the thicker ties in the SNA figures, with F02 having the most transactions at 70, and 37 of 98 fishers only catching and selling once. However, it could be that those fishers were regularly harvesting and selling to Traders 3 and 4, whose data we were unable to collect, but to whom author S.S.S observed fishers selling aquarium fish. On average, fishers caught and sold aquarium fish ten times during the year of data. The variety in node size shows a wide range of gross income earned, discussed further below. We conducted deeper analyses of the SNAs that are beyond the scope of this paper, but we present the figures here to provide a visual aid for understanding the network structure.

Revenue from the aquarium trade

The total gross sales figure for the year of data (accounting for purchasing cost but no other costs) was USD $50,683.45, based on the gross sales of the four respondents. This breaks down as follows: Trader 1 with USD $11,731.90 in sales, Trader 2 with USD $28,141.94 in sales, Buyer 01 with USD $3465.95 in sales, and Buyer 02 with USD $7343.66 in sales. The respondents earned the most gross income from buying and selling blue tang, except for Trader 1, who earned over half of his gross income from buying and selling yellow goby (USD $5943.39).

When looking at fishers and buyers together (excluding B01 and B02, who, as respondents, are inclined to have more revenue accounted for than other buyers and fishers in the network), the highest earner was F01 earning USD $6450.42 for the year (see both Fig. 3 above and Fig. 4 below), and the lowest were four fishers (F96, F46, F47, F88) who only sold fish once for a total of USD $1.74. The average gross individual income was USD $288.44 per fisher/buyer for the year. More important was understanding the proportion of the fishers' and buyers' average gross income this represented. Using IDR 1,750,000 as a baseline average gross monthly income in the source village as explained in the methods, which approximates to USD $1470 per year per individual, and comparing this to the average aquarium fish revenue of the fishers and buyers included in our data, which rounds to USD $288 per year, an average fisher/buyer earns nearly 1/5th (19.6%) of his/her annual gross income from selling aquarium fish. When looking at an individual level, we see that the top 15 earning fishers and buyers capture 43% of the total revenue and that five of the top 15 earners are buyers (orange), while the other nine are fishers (green), and one acts as both (yellow) (see Fig. 4). These results show that while buyers are generally thought to have more capital^44,45,46, some fishers also earn significant gross income from the trade. Again, these results only account for the cost of purchasing fish for traders and buyers. If we estimate fuel costs, the primary cost incurred for fishers, using 9000 IDR/l of fuel (which ranged between ~8000 and 10,000 during data collection) for an average of 7 l per trip (see EC PREP⁴³) and our finding of an average of ten transactions per fishers/buyers during the year of data collection, we find an average cost of 630,000 IDR or $44 USD per year for fuel. This leaves a net annual profit of $244 USD, or 16.6% of their gross annual income derived from selling aquarium fish. Buyers have few costs besides purchasing the fish, which is accounted in our calculations, thus we assume their costs are the same or less than that of fishers, which would cover the initial cost of building a net pen to hold the fish until they sell them, and the miniscule cost of fish food. For both fishers and buyers, these are generous cost estimates considering that fishers often catch blue tang when they are already out fishing for other target species and catch yellow goby in areas close to home, requiring little fuel.

**Fig. 4: Top 15 income earners from selling aquarium fish in the Banggai Region between October 2018 and September 2019.**

Strategy and seasonality

We also developed a linear regression model (see Eq. 3) that was helpful for understanding the relationship between the total number of aquarium fish sold and the type of seller (fisher or buyer), the season (north season, south season, or calm season), and the fish species (blue tang or yellow goby). We found that, on average, fishers sell 81% less individual aquarium fish than buyers, which is logical given that buyers source fish from numerous fishers and sell them forward in the supply chain (see Fig. 5). More counterintuitively, we also found that all participants sell 26% more aquarium fish during the north season, which typically has rougher weather, as compared to the calm season. We examine this finding further in the discussion as it relates to adding diversity and flexibility to participants' livelihood portfolios. Lastly, we found that all participants sell 98% less blue tang than goby across all seasons, which again is logical, as the yellow goby were caught and sold in large numbers as compared to the blue tang. Each of these findings is statistically significant at the α = 0.001% level.

**Fig. 5: Factors influencing total fish sold.**

Finally, we ran an interaction effect model (see Eq. 4) to determine if there were any interactions between the species caught and the seasons which might affect the number of aquarium fish sold by fishers and buyers. We found that the only statistically significant interaction effect (at the 0.05% level) was between the south season and the blue tang, with 36% less blue tang selling on average than goby during this season (see Fig. 6). Or stated inversely, 64% more yellow goby selling on average than blue tang during this season. Additionally, the north season variable, which was significant in our original regression, is insignificant in this interaction effect model, suggesting that the main variation we see across seasons is due to the species type. In other words, the model suggests each target species for the aquarium fishery contributes uniquely to participants' gross income. Author SSS observed that buying and selling aquarium fish supplemented fisher income that was also supplemented by non-fishing income generating activities of both men and women in the household, including boat building; selling local fruits, baked goods, or handicrafts; growing commercially valuable seaweed known locally as "agar agar;" and harvesting tall bamboo poles to build and sell ladders used to harvest cloves during clove season or "musim cinkeh."

**Fig. 6: Weather season interaction with fish species.**

The counterintuitive findings from our regression results show two things: 1) on average, fishers continue catching and even catch more aquarium fish in the north season, which typically has strong wind and large swells making it difficult to catch other target species like octopus; and 2) during the similarly rough weather of the south season many fishers pivot to catching the yellow goby specifically. We now examine these findings further to show that the aquarium fish trade not only contributes to gross participant income but also provides added diversity and flexibility to their livelihood options.

Discussion

New contributions

Our results show that fishers, buyers, and traders in the region both supply a substantial amount of Indonesia's MAT exports and earn a substantial amount of their gross income from the aquarium trade, with the blue tang providing the greatest amount of revenue. We show that most participants catch and/or trade aquarium fish with high frequency and regularity across all weather seasons, with both the blue tang and yellow goby providing supplemental sources of income specifically during rough weather seasons. Our data provide evidence that fishers target specific aquarium species at particular times of year to build their resilience to natural stressors. Taken together, we provide evidence that the MAT helps buffer from seasonal weather disturbances by adding options to fisher, buyer, and trader livelihood portfolios throughout the year. We now further examine these results and their management implications.

Fisher, buyer, and trader contribution to the global MAT

Based on our data, nearly 3% of aquarium fish exported from Indonesia originated from the Banggai region, which is conservative considering we do not present a complete trading network in this paper. Supplying this portion of the country's marine aquarium fish export is quite remarkable considering that Indonesia is comprised of over 13,000 islands⁴⁷. The total number of other aquarium fish source regions supplying the trade is currently undocumented. The occurrence of hubs such as the Banggai Region is likely linked to several factors including logistics, such as being near key points on trade routes, presence of species that are in demand by hobbyists, and, relatedly, overall biodiversity. With 18 of Indonesia's 38 provinces exporting some amount of marine aquarium fish⁶, future studies could focus on these provinces to identify other top source regions. This information would allow the Indonesian government to prioritize monitoring reef health and aquarium species populations in these areas, as well as work with MAT fishers to ensure they have access to and training in harvesting methods that are both efficient and sustainable. We also discovered that fishers, buyers, and traders were highly focused in terms of the species they caught, bought, and sold, principally targeting the high-value blue tang, while also, more recently, targeting the lower-value yellow goby, which was not previously known to be sourced from the region⁴¹. This specialization is dictated by market demand, which in turn determines which species traders and buyers will purchase from fishers. Returning to the concerns of the Blue Justice movement and the language of SDG 14, these findings also highlight the economic contributions that MAT participants provide to the broader Indonesian economy.

MAT contribution to fisher, buyer, and trader livelihood by species

By identifying that, on average, the MAT contributed 20% of gross income for individuals participating in the trade and nearly 17% after accounting for fuel costs, we show that the supplemental income derived from aquarium fish is substantial. Our data show that the blue tang was the primary species traded, providing 87% of total revenue. While a few studies have estimated numbers of fish caught for the MAT (see refs. ^48,49), limited direct source-level data exist: to our knowledge, this is the first study to quantify both volume and income for the blue tang. This species is of particular interest as it was popularized by the Disney movies Finding Nemo (2003) and Finding Dory (2016). With the release of Finding Dory, conservationists were concerned that the film would increase demand for the blue tang, but subsequent studies did not find evidence⁵⁰ of this so-called "Nemo effect"⁵¹. Nevertheless, the blue tang has long been one of the most popular aquarium species and is regularly among the top 20 species by volume imported to the United States^5,14,52. The blue tang is widely, but patchily, distributed across the Indian and Pacific Oceans and is listed as a species of Least Concern by the IUCN^50,53. In theory, this means that blue tang collection does not pose an immediate threat to the species as would targeting protected or endemic species, such as the Banggai cardinalfish^54,55.

Nonetheless, catching the blue tang does pose unique challenges. For example, the blue tang is a relatively difficult aquarium species to catch⁵⁷. The fish exhibit shy behavior, hiding in coral crevices when approached, and prefer areas with strong currents and deeper water than the Banggai cardinalfish and the yellow goby, which are typically found in sheltered coastal areas 1–5 m deep^41,56, clustered around their preferred microhabitats⁵⁷. Thus, fishers targeting blue tang often use compressed air disbursed underwater by hoses known as "hookah" lines when diving to catch blue tang, a practice which can pose serious health risks to the diver^27,58. Additionally, fishers often employ neurotoxins such as potassium cyanide (known locally as "potas") to stun the fish, making them easier to retrieve, as author S.S.S observed in this region. These toxic substances are widely considered to pose sustainability issues⁵⁹, including damaging coral reefs and causing elevated mortality levels of captured fish^60,61.

By contrast, targeting the yellow goby avoids several of the challenges presented by the blue tang, including the need to use neurotoxins to stun the fish, and provides another opportunity for fishers with less specialized equipment to earn money catching aquarium fish⁴¹, especially during the relatively strong winds and big swells of the south season, as evidenced by our regression results. Fishers with less capital can catch these fish in shallow coral reef areas protected by mangroves near the source village with a simple, human-powered "sampan" (small wooden canoe), and they do not need a boat engine or a hookah-diving compressor as they do to target blue tang. The yellow goby was also recently found to be the most sustainable aquarium species to catch out of the 72 reef species evaluated by a Productivity Susceptibility Analysis that considers ten life history attributes and "12 catchability, management, and fishing practice attributes that are location-specific" (Dee et al.⁵⁹, at p. 2). However, one concern with catching this species in the Banggai Archipelago is the observed behavior of fishers pulling up entire coral heads on which the goby congregate to deposit them more easily into the "serok" net they use to catch the individuals, which is likely to result in the mortality of the coral colony, leading to a decline in live coral cover and habitat niches for coral-associated fish⁴¹. Additionally, while targeting yellow goby may appeal to fishers lacking access to the equipment needed to catch blue tang, other fishers may prefer to focus on blue tang, due to its higher value as well as the adventure and bravado associated with catching species via compressor diving²⁷.

Diversification and resilience

Because small-scale fishers can be particularly vulnerable to unpredictable ecological disturbances and economic change³⁹, scholars have argued for an approach to fisheries management that fosters resilience in the face of uncertainty^{25,62,63,64,65,66,67}. Our linear regression models revealed that both the blue tang and yellow goby help build fisher resiliency in the region by providing added flexibility in seasons of typically bad weather with strong wind and large swells that create choppy sea conditions. While these bad weather conditions can vary from island to island⁶⁸, fishers in Banggai noted two distinct rough weather seasons, "musim utara" or north season, and "musim selatan," or south season⁴⁸. During these two seasons, strong wind and large swells can make it difficult for fishers to target their primary catch, which varied among fishers but was observed to include octopus, squid, and popular food fish species, like snapper and grouper. However, despite these challenges, the regression reveals that, on average, fishers and buyers sell a higher number of blue tang and goby during the north season. We hypothesize that this difference is because the locations fishers most often frequent to catch blue tang are largely protected from the north season wind and swell direction, while their locations for other target species (including octopus and squid) are not; thus, they focus energy on catching blue tang. However, during the south season, these blue tang locations are more exposed to the wind and swell, while locations for the yellow goby remain protected. Without both species being accessible during the south season, the statistical relationship is non-significant. However, our interaction model showed that blue tang sales decreased in the south season relative to goby sales, suggesting that the yellow goby can continue to provide additional income during this season of rough weather due to its preference for shallow protected habitat.

Taken together, the findings show that each aquarium species contributes uniquely to fisher, buyer, and trader income, especially during poor weather. Thus, the aquarium trade allows fishers and traders to have flexibility to move from specializing during favorable conditions to diversifying during unfavorable conditions²⁵. These findings also contribute to understanding how weather influences fisher behavior, a critical and understudied aspect of marine resource management⁶⁹. Additionally, participant observation showed that fishers with less capital can still access the yellow goby, providing alternative income options for less-resourced individuals participating in the trade⁴¹. Thus, the aquarium trade represents another option for livelihood diversification, which fishers and their families can add to their "livelihood constellations," defined as "several activities that individuals and households combine for income, health, and well-being" (Griffith⁷⁰ at p. 82). Families could add selling aquarium fish to their constellation, often without adding significant additional costs, which could supplement the other non-fishing income-generating activities author S.S.S observed.

According to the livelihood resilience strategies identified by Marschke and Berkes³⁷, livelihood diversification efforts need to build the capacity of a household's flexibility to earn income to be considered a resilience-building measure. We argue that fishing families in our study use the opportunity to earn additional income from aquarium fishing as a resilience-building measure that supports their capacity to manage future change⁷¹ and sustain well-being⁷². Such resilience-building measures or strategies will become increasingly important as climate change continues to affect the region⁵⁸. Indeed, fishers noted that the year the lead author collected the data reported here, the north season was lasting longer than it had historically⁷³, which supports findings from past studies in the BOKEP region (see EC PREP⁴³). Additionally, longitudinal weather studies support these first-hand reports of changing weather patterns in the region^74,75. If the rough weather seasons continue to extend, both the blue tang and yellow goby can potentially continue providing alternate sources of income due to the more protected areas they inhabit compared to other target species, depending of course upon how climate change affects each species population size and distribution. In addition to potentially providing a buffer to climatic changes, targeting a wider variety of species via the aquarium trade may also be important for ecological sustainability, by placing less pressure on any one species. Again, more studies need to be conducted to understand the ecological effects of species diversification, as in other small-scale fisheries²⁵.

One caveat to the added flexibility and diversity provided by the fishery is that greater overall community resilience does not necessarily mean an equitable distribution of and/or access to resources across individuals⁷⁶. This is evidenced by our data; while, on average, fishers and buyers earned about 20% of their income from the aquarium trade, when considering individual earnings, the top 15 earners captured nearly half of the revenue. Additionally, though catching aquarium fish may be a resilience-building strategy, according to the Sustainable Livelihoods Approach and Framework⁷⁷, which helps to determine the sustainability of a particular livelihood constellation, such strategies will be enabled or hindered by institutions and social processes among other factors⁷⁸. In the BOKEP Region, as in many parts of Indonesia, the patron–client relati...

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