THE MYSTERIOUS LIVES OF SEADRAGONS
How captive breeding is allowing us to better understand and protect these seahorse relatives
WHILE SEADRAGONS
are regarded as some of the most ornately beautiful marine species in the world, very little is actually known about them. As masters of camouflage, with small geographic ranges, it’s no wonder their lives are wrapped in mystery. Although they were documented as early as the mid-1800s, seadragon research is still a relatively new field of marine biology.
ASSESSING THESE SYNGNATHIDS
Belonging to the Syngnathid family, the three known species of seadragon are closely related to seahorses and pipefish. Like their relatives, male seadragons are in fact responsible for carrying the fertilised eggs until they hatch. The leafy seadragon (Phycodurus eques), the common or weedy seadragon (Phyllopteryx taeniolatus), and the newly discovered ruby seadragon (Phyllopteryx dewysea) all inhabit relatively small natural ranges in the coastal waters of southern and western Australia. Their unique colourations and leaf-like appendages help them to blend in extremely well with their seaweed and kelp habitats; especially since they seem to have mastered the art of swaying back and forth with the waves, just as the surrounding marine algae does.
Despite their uncanny ability to hide from their natural predators, seadragons are facing threats from other sources. When first assessed in 1996 by the IUCN (International Union for Conservation of Nature), seadragons were listed as “Data Deficient” due to an overall lack of knowledge. With the inclusion of more scientific research findings, the 2006 IUCN Red List of Threatened Species recognises both weedy and leafy seadragons as being “Near Threatened” based on their small geographic ranges. However, a severe lack of information regarding seadragon population size, population fluctuations, and life history traits has prevented their conservation status from being assessed by these factors.
STEMMING THE TRADE
Despite insufficient scientific data, there is an export ban on seadragons under Australian law. This means that the removal of seadragons from the wild for export to other countries is strictly prohibited without a permit issued from the Minister of the Environment; while domestic collection laws are set by individual states. Yet this was not always the case. Before protections were put into place, collection of these animals for aquaria was common and seemed to have had a negative effect on their populations. With protection laws set, and seadragons being highly sensitive to living in captivity, the number of seadragons being taken from the wild for household and small-scale aquariums decreased drastically in the mid-1990s. There is one known private seadragon distributor with permits to collect a few egg-bearing males from the wild each year and successfully raise the young. However, this is even under heavy review by the government since it is not clear who the captive raised seadragons are actually being sold to each year, as well as their survival rate once sold. Only large public aquariums with highly knowledgeable aquarists are truly able to keep these animals alive by meeting their specialised needs in captivity.
Over the years, several public aquariums around the world have been able to obtain permits to collect and export wild-caught seadragons from
Australia to put on display in their exhibits. Birch Aquarium at Scripps Institution of Oceanography, located in La Jolla, California, was able to put their first weedy seadragon on display in 1996. With the right amenities and knowledge necessary to care for a seadragon, Birch Aquarium put the specimen on display to simply share its beauty and rarity with visitors. As time went on, they obtained several more weedy and leafy seadragons from a permitted captive breeder, due to the fact that they seemed to be a favourite amongst visitors.
IN SERVICE TO SCIENCE
Today, however, the seadragons at
Birch Aquarium at Scripps are kept not simply to inspire visitors, but for the advancement of scientific knowledge regarding these animals. Having already discovered a great deal about seadragon behaviour and life history by simply caring for those on exhibit, Birch Aquarium’s co-curator and lead seadragon aquarist, Leslee Matsushige, started the aquarium’s seadragon captive breeding programme in order to uncover cutting-edge and vital information about their mating and reproductive strategies.
Until now, only a handful of public aquariums have even had a successful seadragon breeding event, and each of these occurred either by chance, or did not successfully occur a second time. Additionally, seadragon mating has never been observed in the wild. Matsushige, however, is optimistic about the programme.
As a world leader in captive seahorse breeding, there is great potential for Birch Aquarium to successfully breed seadragons as well. While they have so far successfully raised only one seadragon from egg to mature adult,
A severe lack of information has prevented their conservation status from being assessed
they are learning more and more each day about this animal’s reproductive strategies. Additionally, they are seeing increases in the number of eggs that these captive females are producing each year, thus increasing the chances of more successful reproductive events to occur in the future.
PRESSURE OFF THE WILD
Just as the Birch Aquarium seahorse breeding programme is focused on advancing scientific knowledge and increasing the conservation of seahorses worldwide, the seadragon breeding programme has the same goals.
Captive breeding programmes like this are becoming increasingly important for scientists as seadragon populations become more threatened by habitat loss and degradation, and as collection and research permits become more difficult to get. By distributing captive bred Syngnathids to aquariums worldwide, Birch Aquarium is limiting the number of seahorses, and soon seadragons, that are taken from the wild, thus contributing to their conservation.
RELATIONSHIPS AND BEHAVIOUR
While the seadragon breeding programme, has already played a crucial role in expanding our understanding of seadragons, it is still in its infancy. An important collaboration between Matsushige and Dr. Greg Rouse of the Scripps Institution of Oceanography has been present from the start of the program in 2012.
Rouse, an Australian native, studies population genetics of seadragons in order to assess their diversity. While Rouse has provided crucial information to Matsushige regarding wild seadragon populations, the captive seadragons at Birch Aquarium have also provided Rouse with important information regarding his research. Tissue and waste samples from Birch Aquarium’s captive seadragons have helped to increase the amount of DNA that Rouse and colleagues have had available when conducting their genetic studies.
Rouse has now determined that, genetically, the weedy seadragon and the leafy seadragon are in fact each other’s closest living relatives, and that weedy seadragon populations are in fact one single species, not two. In terms of genetic diversity, they have found that the leafy seadragon has relatively low genetic diversity throughout its entire population, while the weedy seadragon populates some geographic areas of low genetic diversity and other geographic areas of high genetic diversity. These results are fundamentally important in trying to better understand and protect wild populations of seadragons.
Experiments including acoustic research at Birch Aquarium have found that seadragons actually make a clicking sound when they are feeding, similar to their seahorse relatives. Learning more about these kinds of aspects of their behavioural ecology from experiments like this expands our knowledge of these animals even further.
In terms of conservation, all findings from Rouse’s seadragon research are being used to inform Australian policy makers on how to best protect wild populations. These kinds of captive seadragon breeding programmes, in partnership with scientific research, are helping to unwrap the mystery surrounding these incredible animals, and ultimately, to better protect them.