Slender Sunfish stranding

It must have been sad to watch but wow, what a story.

The photos above, plus another two (see links below), were taken by hylacola. They record a mass stranding of Slender Sunfish, Ranzania laevis, on 16 May 2014.

Slender Sunfish on the beach (1)
Slender Sunfish on the beach (2)

Interestingly, the southern coastline of Western Australia around Albany (Peaceful Bay to Bremer Bay) seems to be a hot spot for mass strandings of Slender Sunfish, with strandings documented in 1928 (Gomon et al., 2008), 1941, 2008 (with map), this record in 2014 and another in 2016 (view video).

One of my colleagues wondered if the fish were aggregating in shallow water to spawn. Smith, et al. (2010), however, stated that "Gonad development indicated spawning was not imminent. The cause of the strandings was unclear, although advection of fish to the south coast by the tropical Leeuwin Current was strongly implicated." In other words, the strong Leeuwin Current that flows down the coast of Western Australia may have swept the fish 'around the corner' of the State, then onto the southern coast.

The Slender Sunfish occurs globally in tropical and temperate seas. In Australian waters, it is known from tropical northern Queensland, right around the temperate south of the country and north to North West Cape, Western Australia.

Perhaps surprisingly, given its unusual shape, the Slender Sunfish is a strong swimmer. (View video)

References:

1. Gomon, M.F., Bray, D. & R.H. Kuiter (Eds). 2008. The Fishes of Australia's Southern Coast. Reed New Holland. Pp. 928.
2. Smith, K.A., Hammond, M. & P G. Close, 2010. Aggregation and stranding of elongate sunfish (Ranzania laevis) (Pisces:Molidae) (Pennant, 1776) on the southern coast of Western Australia. Journal of the Royal Society of Western Australia, 93: 181–188.