Ocean Sunfish (Mola mola) off Masset, Haida Gwaii

Observation by David Bradley:

Seeing an ocean sunfish (Mola mola) in temperate waters is unusual for a tropical fish. The one shown in Figures 1-3 was observed off Masset, Haida Gwaii on 1 August 2017.

Comment by Tom Okey:

Although the latitude of coastal British Columbia is identified as within the normal range of ocean sunfish (Mola mola) based on Aquamaps modelling (see Figure 4), until recently they were not sighted north of the southwest coast of Vancouver Island (see Figure 5). This is likely because this tropical/temperate species was associated with the North Pacific Current, which demarcates the warmer North Pacific Gyre from the colder Subpolar Gyre. However, sightings in the coastal marine waters of British Columbia have increased considerably in recent years, possibly due to warming of waters north of the North Pacific Current. Williams et al. (2007) and Thys and Williams (2013) describe a concentration of Mola mola just south of Haida Gwaii.

Resources:

The Ocean Sunfish project

Ocean sunfish on Fishbase

References:

Eschmeyer, W.N., E.S. Herald and H. Hammann, 1983. A field guide to Pacific coast fishes of North America. Boston (MA, USA): Houghton Mifflin Company. xii+336 p.

Hubbs, C.L., 1948. Changes in the fish fauna of western North America correlated with changes in ocean temperature. J. mar. Res, 7(3), pp.459-482.

Thys, T. and R. Williams. 2013. Ocean sunfish in Canadian Pacific waters: Summer hotspot for a jelly-eating giant?. In Oceans-San Diego, September 2013 (pp. 1-5). IEEE.

Williams, R., Okey, T.A., Wallace, S.S. and Gallucci, V.F., 2010. Shark aggregation in coastal waters of British Columbia. Marine Ecology Progress Series, 414, pp.249-256.

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