Sustainable wild fisheries are catching on, but there's a long way to go before sufficient numbers are established. Ross Burridge investigates one such project in Brazil.
The Amazon River region is home to one third of all living species and covers 40% of the South American continent, its staggering biodiversity lending it not just supreme ecological importance but a special place in any fishkeeper’s imagination.
More than 3,000 species of fish are so far known from its tributaries, including many aquarium favourites such angelfish, Rams, Oscars, a host of shimmering tetras — and, perhaps the most iconic, the varying forms of Discus from the genus Symphysodon.
Yet with 90% of the ornamental industry centred on freshwater species, marine is not the only market needing to examine its eco-credentials. As vast as the Amazon river system is, the complex lifecycles and small scale populations of many species mean that poor fishery management can lead to a rapid collapse — as happened in the Mamirauá region of Brazil during the late 1980s.
These days, the angelfish and Neon tetras in your tank are more likely to have started life in a fibreglass vat or vast pond in Singapore than the flooded forests of native South America. The growth of huge ornamental fish farms throughout Asia has been fuelled by the belief among consumers that captive-bred fish are naturally more ‘responsible’. However, that’s not necessarily the case.
Mamirauá was granted reserve status by the international Ramsar Convention of the IUCN (International Union for Conservation of Nature), in 1996, joining a network of more than 22,000 square miles of globally important wetland rainforest.
Rather than isolating itself, it has become home to a series of pioneering sustainability projects. Working in conjunction with research scientists, local communities act as stewards of the environment and its resources – including its ornamental fish stocks.
Brazil’s ornamental fish industry is worth an estimated US $200 million (£125 million) annually, with around 20 million fish, mainly Cardinal tetras, ending up primarily in the USA, Japan and Europe. Previous projects had provided an inspiring model, including a major fishery based in Barcelos in the north of Brazil’s Amazonas state. However, the flooded forest environments of Mamirauá and its sister reserve, Amanã, presented their own challenges.
In 2005 the reserves’ managing body contacted the Zoological Society of London (ZSL) to discuss a new feasibility study.
ZSL secured funding from the UK’s Darwin Initiative, and eventually became a key partner in the research, sending staff to Brazil to advise on logistics and welfare. They focused on appropriate species selection, capture, handling and transport methods, as well as monitoring mortality during processing.
Years of sampling in other areas had identified a variety of candidates for study, but some 80% were immediately dismissed due to export restrictions or a lack of consistent value in the aquarium trade.
Brian Zimmerman, assistant curator at London Zoo Aquarium, was closely involved in the project’s inception. "The problem with the wild trade is very boom and bust," he explains. "There will be a particular species that’s new, suddenly everyone wants a fish and it’s worth £50. Then as soon as there are enough on the market, people start to breed them and value drops."
A handful of viable species were selected from Mamirauá for further research — including angelfish and Oscars — while 19 were deemed suitable from Amanã: several Apistogramma dwarf cichlids, a number of Carnegiella hatchetfish and four colour varieties of Discus.
A mix of behavioural study and sampling then saw biologists evaluating population dynamics, migration patterns, life history, behaviour and feeding ecology. River collections of some 100 individuals of target fish each month were undertaken. One third were examined to retrieve stomach contents and study sexual structures, scale samples, vertebrae and otoliths — bony head structures which yield similar information to that of tree growth rings.
This gave further insights into reproductive biology and growth patterns, with tissue samples contributing to genetic studies. This research was translated into practical guidelines, many related to the region’s intense seasonality.
Eight different local communities became involved, intending to provide a viable alternative income to the area’s main subsistence activities of agriculture, hunting and commercial food fishery — all of which have potentially negative environmental associations.
Science was also applied to get these community-led aspects under way. A sociologist analysed local spending habits and contributed a major anthropological study. Workshops covered social organisation, associative group practices and financial administration, and there were more practical sessions on collection, handling and transportation methods.
Representatives were also involved in negotiations with potential exporters in an effort to make the operation fair trade from the beginning.
Making this work in the wider world presents challenges and IBAMA, Brazil’s environmental agency, publishes a ‘white list’ of allowed species for export, thwarting attempts to introduce more unusual, high value or attention-grabbing species.
The research also suggests that many popular species are ‘loss leaders’ in the UK retail market, simply subsidising sales of items such as aquariums and gravel.
Against a backdrop of consumer perception that wild-caught fish is ‘bad’, the project concludes that ‘strong marketing’ is vital to create interest and justify the extra costs of the process.
However, it’s also an ethical issue. As Brian Zimmerman explains: "A lot of people have this false belief that they should only get captive-bred fish, but huge farms in Asia are causing major problems. They are introducing non-native species or diseases into the environment, consuming a lot of water and using a lot of chemicals and hormones.
"The husbandry and welfare is also often very lax," he continues, "so we’d say it’s actually not bad to be buying wild-caught fish - if they’re sustaining local communities."
Despite these hurdles, the reserve’s management institute published an in-depth study in 2008. This announced that researchers and reserve inhabitants had arrived in Manaus, and were beginning export negotiations for the first sustainably-managed Discus.
We are yet to see these fish arrive in any numbers in the UK, and are a long way from this becoming the norm. It’s unclear whether market forces can support sustainable extraction or the fair trade practices it implies. Yet without such projects the industry faces a tough ethical future, reliant on ad-hoc wild collections and a commercial breeding model.
Sustainable species from Mamirauá
- Common angelfish, Pterophyllum scalare: Although easily bred in captivity, wild-caught angels are prized among some hobbyists, particularly when breeding pairs.
- Flag cichlid, Mesonauta insignis: An often overlooked aquarium cichlid. Some consider wild specimens exhibit finer coloration than intensively-bred captive populations.
- Oscar, Astronotus ocellatus: A number of related species are common food fish in the region, but this fish is also commonly seen in the trade and remains popular.
- Discus, Symphysodon aequifasciatus: Four colour types of Discus were collected: regular, spotted, half-spotted and royal. It’s one of the few species of wild fish actively sought.
- Silver arowana, Osteoglossum bicirrhosum: A popular local food fish, these are a controversial choice for the ornamental market, with few hobbyists really equipped to house them successfully.
Taking Discus captive…
The principal capture season is during the low water periods of October and November. During seasonal floods the fish are scattered more widely through the flooded forest, foraging and preparing to breed.
There are two strategies for capturing Discus. At night and using a head torch, they’re found searching in stream border vegetation, or under trees, and can be simply scooped up with a rapiché — a soft net, tied round a metal ring.
During the day, a drag net is used, fencing them in the trees. Captured fish are kept in mesh cages installed in the flooded forest before being collected for export.
For smaller shoaling species, fishermen walk knee-deep into the forest edge, using a canoe paddle to herd them into a net with a loose opening at the front. A woven basket, lined with plastic, is in the canoe and the netted fish are scooped from net to basket using a small plastic bowl. As they never touch the sides, abrasions and stress are minimal.
This method is commonly used for small tetras, pencilfish, Rummynose tetras and hatchetfish.
This item was first published in the December 2009 issue of Practical Fishkeeping magazine. It may not be reproduced without written permission.