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Marine Ecology Progress Series

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MEPS 422:253-264 (2011)  -  DOI:

Demographics and vulnerability of a unique Australian fish, the weedy seadragon Phyllopteryx taeniolatus

Jaime Sanchez-Camara1, Keith Martin-Smith2, David J. Booth3, Juan Fritschi1, Xavier Turon4,*

1Aquadec Aquariums S.L., 18600 Motril, Granada, Spain
2Australian Antarctic Division, Australian Government Department of Environment, Water, Heritage and the Arts, Kingston, Tasmania 7050, Australia
3Department of Environmental Sciences, University of Technology, Sydney, PO Box 123, Broadway, Sydney, New South Wales 2007, Australia
4Department of Marine Ecology, Center for Advanced Studies of Blanes (CEAB, CSIC), 17300 Blanes (Girona), Spain
*Corresponding author. Email:

ABSTRACT: The weedy seadragon Phyllopteryx taeniolatus is a vulnerable and endemic Australian fish and also an icon and flagship species for marine conservation. However, little is known about its population dynamics, which hinders the establishment of conservation policies. We have previously demonstrated seadragons to be highly site-attached, so we estimated population densities, growth and survival of weedy seadragons using mark-recapture techniques at 5 sites in New South Wales (NSW, 34°S) and Tasmania (TAS, 43°S), near the northern and southeastern limit of distribution for the species, over a 7 yr period. Population densities varied from ca. 10 to 70 seadragons ha–1 depending on site and year. There was a significant decline in the number of weedy seadragon sightings per unit area searched in 2 out of 3 study sites near Sydney, NSW, from 2001 to 2007. There was also a decline at one of the 2 sites surveyed in the lower Derwent Estuary, TAS, in 2009 compared to 2003 and 2004. Survival rates at NSW sites ranged from 0.62 to 0.65 yr–1 and were higher at TAS sites where they ranged from 0.71 to 0.77 yr–1. Birth occurred approximately 3 mo later and seadragons exhibited significant slower growth in TAS (maximum adult size × growth rate parameter, L × k = 31.02) compared to NSW (L × k = 55.15). This study is the first population assessment of seadragons over ecologically relevant spatial and temporal scales, and shows differences in the dynamics of populations at different latitudes. It also shows declines in some populations at widely separated sites. Determining whether these declines are natural interannual fluctuations or whether they are caused by environmental or habitat changes must be a priority for conservation.

KEY WORDS: Mark-recapture analyses · Conservation · Growth · Survival rate · Population dynamics · Endemic Australian fish

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Cite this article as: Sanchez-Camara J, Martin-Smith K, Booth DJ, Fritschi J, Turon X (2011) Demographics and vulnerability of a unique Australian fish, the weedy seadragon Phyllopteryx taeniolatus. Mar Ecol Prog Ser 422:253-264.

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