"It is not uncommon to see an increase in mortality over summer particularly on our westerly Pelorus farms and this is one of the main reasons we have applied for Blue Endeavour in the cooler, deeper and faster current conditions of the Cook Strait," it said.
The resource consent hearing was completed in December and a decision is expected in the next few months.
NZ King Salmon's share price closed down 14c or 11.57 per cent to $1.07.
Last September, NZ King Salmon said its net loss came to $5.6m in the six months to July, driven by small fish.
The shortfall equalled the previous first half's loss.
NZ King Salmon is the world's largest aquaculture producer of premium king salmon.