Climate variability and massive mortalities challenge giant clam conservation and management efforts in French Polynesia atolls

Published source details Andréfouët S., Van W.S., Gaertner-Mazouni N., Menkes C., Gilbert A. & Remoissenet G. (2013) Climate variability and massive mortalities challenge giant clam conservation and management efforts in French Polynesia atolls. Biological Conservation, 160, 190-199.
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This study is summarised as evidence for the following.

	Action	Category
	Designate a Marine Protected Area and prohibit all types of fishing Action Link

Designate a Marine Protected Area and prohibit all types of fishing

A before-and-after, site comparison study in 2004 and 2012 in 18–19 sites of sandy and coral seabed in Tatakoto Atoll, South Pacific Ocean, French Polynesia (Andréfouët et al. 2013) found that over the eight years after designating a marine protected area prohibiting all fishing (no-take), abundance and biomass of giant clams Tridacna maxima appeared higher inside compared to outside the no-take area, but were decreasing in both areas. Results were not tested for statistical significance. Abundance of clams decreased inside (from 119 to 11 clams/m²) and outside (from 9 to 3 clams/m²) the no-take zone. Abundances in 2012 corresponded to only 9.5% of the 2004 abundance for inside and 41% for outside the no-take zone. Total biomass of clams also decreased inside (from 256 to 32 tonnes) and outside (from 126 to 61 tonnes) the no-take zone. Authors state that decreases were linked with mass-mortalities occurring in 2009 due to a high range of temperature variations. In 2004 a 0.5 km² no-take zone was designated for giant clam conservation in Tatakoto Atoll; the rest of the Atoll is open to hand-harvest of clams by local fishers only. Five to six sites inside the no-take zone and 13 sites outside (within the Atoll) were surveyed in 2004 before designation and in 2012. Snorkelers counted and measured all clams inside six 0.25 m² quadrats/site (methods fully described in Gilbert et al. 2006).
_{Gilbert A., Andréfouët S., Yan L. & Remoissenet G. (2006). The giant clam Tridacna maxima communities of three French Polynesia islands: comparison of their population sizes and structures at early stages of their exploitation. ICES Journal of Marine Science, 63, 1573–1589.}

(Summarised by: Anaëlle Lemasson)