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

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 jelly¢sh prey species found throughout the region: Rhizostoma octopus, Chrysaora hysoscella and Cyanea capillata. A total area of 7850 km 2 was surveyed over the three years with an observed abundance of 68 sun¢sh giving a density of 0.98 ind/100 km 2 . Although modest, these ¢ndings highlight that the species is more common than once thought around Britain and Ireland and an order of magnitude greater than the other apex jelly¢sh predator found in the region, the leatherback turtle (Dermochelys coriacea). Furthermore, the distribution of sun¢sh 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 jelly¢sh species) was less than the observed co-occurrence with the implication that neither jelly¢sh nor sun¢sh were randomly distributed but co-occurred more in the same areas than expected by chance. Finally, observed sun¢sh were typically small ($1m or less) and seen to either bask or actively swim at the surface.

Spatial and Temporal Baseline Information on Marine Megafauna-Data Facilitated by a Wildlife Tour Operator

“…Ocean sunfish were also occasionally observed breaching (13.4% of all records) which may decrease parasite load [63]. Our observations support Open Journal of Marine Science previous studies on sunfish being active in coastal, temperate seas during summer [3] [6]. It has also been suggested that the increased presence of smaller, young sunfish in coastal waters may be owing to local current regimes carrying them further inshore than adults [3].…”

Phylogenetic relationship of two Mola sunfishes (Tetraodontiformes: Molidae) occurring around the coast of Japan, with notes on their geographical distribution and morphological characteristics

“…Recent studies, using pop-up satellite archival tags to establish swimming patterns and thermal preferences (Seitz et al 2002;Bass et al 2005), acoustic transmitters to record patterns of diel movement (Cartamil and Lowe 2004) and aerial surveys of distribution and abundance (Houghton et al 2006), have indicated that ocean sunfishes are active swimmers. A possible migration route of group A, ''northward from Micronesia through Ogasawara Island to the Pacific coast of northeastern Japan,'' as also found with the skipjack Katsuwonus pelamis and the yellowfin tuna Thunnus albacares (Joseph et al 1988), may well explain the distribution pattern of group A around Ogasawara Island and the Pacific coast of northeastern Japan.…”

Foods of Velella velella (Cnidaria: Hydrozoa) in algal rafts and its distribution in Irish seas

“…Large numbers of the European storm petrel, Hydrobates pelagicus (Linnaeus), forage in the Celtic Sea during the summer months and may take from the sea surface small fish, plankton, mollusks, crustaceans, and V. velella, as do Leach's storm-petrels in the northeast Pacific (Vermeer & Devito, 1988). Other probable predators of V. velella in Irish waters include the ocean sunfish, Mola mola (Linnaeus), and leatherback turtles, Dermochelys coriacea Vandelli, which feed on surface aggregations of gelatinous prey (Houghton et al, 2006b).…”