The unpredictability of wild seed supply is a severe obstacle for sustainable production in mussel aquaculture globally. An improved understanding of the spawning of wild broodstock and subsequent patterns of larval dispersal and settlement could help to greatly progress the sustainable management of wild spat resources and increase mussel spat supply. In this study, the shell microchemistry of green-lipped mussels, Perna canaliculus, that had recently settled on an offshore mussel farm in the Bay of Plenty, New Zealand, was used to identify their patterns of larval dispersal and likely natal locations.
The shell microchemistry profile of mussel spat settling on the offshore mussel farm were compared with those from mussels cultured in situ at 22 sites (~6 km apart) arranged around Bay of Plenty, New Zealand, over two consecutive months. Six elemental signatures (Li, Co, Ni, Ba, La and U) were the primary drivers for correctly reassigning shells back to their individual natal sites with an average of 58% accuracy,
ranging from 20% (near Hikuwai Beach) to 78% (on West Spat Farm). Grouping of in situ sites increased the mean accuracy to 75% but reduced spatial resolution to ~40 km. The microchemistry tracked ~160 spat arriving on the mussel farm back to two main natal sites near the Ohiwa Harbour, which accounted for 85% of mussels arriving on the mussel farm.
Overall, this study evaluated the reliability of shell microchemistry for tracking mussel seed back to their source. The information from this study will assist with managing local mussel seed resources in the Bay of Plenty.