Palau's giant clams withstand pressures from human activity, new study finds
By Pacific Island Times News Staff
Despite pressures from tourism and fishing, giant clam populations remain abundant and healthy throughout Palau, according to a new study released by Palau International Coral Reef Center.
The study, published and authored by former PICRC researcher Lincoln Rehm, attributes Palau’s healthy clam populations to Palau's conservation measures such as marine protected areas and bans on exporting clams.
Oruer was determined to be the most abundant clam species, followed by melibes and ribkungal. Kism, oktang and duadeb were less common.
Oruer, melibes and ribkungal were also found to be more abundant in Palau than other areas of Micronesia and the Indo-Pacific. Oruer in particular has become scarce in other Micronesian islands but remains dense in Palau.
Despite a fourfold increase in tourism in the past decade and rising fishing pressure, the implementation of marine protected areas and export bans seem to have succeeded in preserving Palau’s clams, the study.
The Palau Mariculture Demonstration Center has also likely reduced fishing of wild clams by supporting local clam aquaculture, according to the study co-authored by PICRC Research Office Assistant Randa Jonathan and former researcher Lincy Marino.
However, the authors also caution that Palau’s clam populations still face challenges. The study found low numbers of large adult oruer and ribkungal, which signals high fishing pressure and could limit the species’ ability to reproduce in the future.
To continue supporting these populations, and to replenish dwindling kism, oktang and duadeb, the authors recommend continued investment in clam aquaculture, restocking wild populations with farmed clams and implementing harvest limits. These measures could ensure that giant clams remain a valuable economic and food resource for Palau into the future.
In the global oceanscape, however, giant clams are facing other challenges that might threaten their survival.
"In recent years, we are recognizing that giant clams are not only threatened by overexploitation by humans, but are also threatened by a suite of environmental change drivers including 1) global change stressors, such as climate change, global warming and ocean acidification, and 2) local and regional stressors from agriculture and urbanization, such as turbidity and sedimentation," according to another study published in the Conservation Physiology.
The study, authored by Sue-Ann Watson and Mei Lin Neo, was released in December 2021.
"Of the global pressures on marine life, pollution and climate change continue to occur at peak pressures," the study said. "Crucially, the effects of local to global environmental stressors not only act in isolation, but also in concert, with potentially unknown synergistic effects occurring within the complex coastal environments that giant clams inhabit."