Journal of the Marine Biological Association of the United Kingdom



Research Article

The ocean sunfish Mola mola: insights into distribution, abundance and behaviour in the Irish and Celtic Seas


Jonathan D.R.  Houghton a1c1, Thomas K.  Doyle a2, John  Davenport a2 and Graeme C.  Hays a1
a1 Department of Biological Sciences, Institute of Environmental Sustainability, University of Wales Swansea, Singleton Park, Swansea, UK, SA2 8PP.
a2 Department of Zoology, Ecology and Plant Sciences, Lee Maltings, Prospect Row, Cork, Ireland

Article author query
houghton jd   [PubMed][Google Scholar] 
doyle tk   [PubMed][Google Scholar] 
davenport j   [PubMed][Google Scholar] 
hays gc   [PubMed][Google Scholar] 

Abstract

Here we provide baseline data on the distribution and abundance of Mola mola within the Irish and Celtic Seas, made during aerial surveys from June to October during 2003–2005. These data were considered in conjunction with concurrent observations of three potential jellyfish prey species found throughout the region: Rhizostoma octopus, Chrysaora hysoscella and Cyanea capillata. A total area of 7850 km2 was surveyed over the three years with an observed abundance of 68 sunfish giving a density of 0.98 ind/100 km2. Although modest, these findings highlight that the species is more common than once thought around Britain and Ireland and an order of magnitude greater than the other apex jellyfish predator found in the region, the leatherback turtle (Dermochelys coriacea). Furthermore, the distribution of sunfish sightings was inconsistent with the extensive aggregations of Rhizostoma octopus found throughout the study area. The modelled distributions of predator–prey co-occurrence (using data for all three jellyfish species) was less than the observed co-occurrence with the implication that neither jellyfish nor sunfish were randomly distributed but co-occurred more in the same areas than expected by chance. Finally, observed sunfish were typically small ([similar]1 m or less) and seen to either bask or actively swim at the surface.

(Published Online August 25 2006)
(Received January 21 2006)
(Accepted July 21 2006)


Correspondence:
c1 e-mail: j.d.r.houghton@swansea.ac.uk