Toheroa clam up over reasons for population non-recovery

Embargoed until: Publicly released: 2022-01-14 11:34

New Zealand

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The toheroa suffered from decades of overfishing in the 1900s, but 40 years of prohibition on commercial and recreational fishing have done little to help their populations recover. In a bid to uncover the ongoing barriers to the recovery of this native clam, researchers have analysed the prevalence of parasites and diseases in toheroa populations all over New Zealand. Intracellular microcolonies of bacteria (IMCs) were detected in all populations, and unhealthy clams were more likely to be infected. Researchers caution that we can’t know for sure whether poor fitness leads to a higher chance of infection with IMCs, or if IMCs decrease fitness, though the pathogen has previously been associated with the decline of several shellfish populations in Aotearoa. Despite the remaining uncertainty, the study will provide useful baseline data for future research exploring why the species has struggled to recover for so long.