Assessment of scallop spat ( Pecten novaezelandiae ) transport, handling and tagging mortality for wild fishery enhancement, Golden Bay, New Zealand

Abstract

The formerly lucrative Pecten novaezelandiae Southern Scallop fishery in New Zealand has experienced significant declines that have resulted in changes to spat handling and transport methods, with untested effects on spat survival. Experiments were carried out on board a harvest vessel to test the effects of spat handling, emersion, immersion and transport for up to 6 h post-harvest. Spat were then transferred to lantern cages for 7 d with lantern and spat bag controls, and examined for mortality. Length frequency analysis revealed smaller spat (mean: 20.4 mm ±0.3 95%CI) were more susceptible to handling and transport than larger individuals (mean: 25.9 mm ±0.23), but ANOVA tests did not reveal any differences between emersed or immersed treatments that appeared related to handling stress. The most severe treatment, transporting spat for 3 h at the bottom of a bulk bag to emulate crushing, had no detectable effect. Factors other than spat handling stress potentially responsible for the ongoing lack of recovery via enhanced spat in this fishery are discussed.