A small family fishing company has self-reported the capture of 18 endangered black petrels and two flesh-footed shearwaters over a six-day period in the past week.

Each time a capture occurred, the vessel moved its fishing over 30 kilometres in an attempt to avoid the birds.

The owners of the company and the skipper of the vessel are devastated about the captures, which happened while longlining with full mitigation deployed.

The company, crew and skipper are cooperating fully with agencies to understand why such an unusually large number of birds were captured over this period.

A camera was operating on the vessel at the times of the captures and that footage will be examined as a part of establishing what may have been the cause.

This company is actively engaged in seabird conservation and educating others and the incidents have affected them deeply.

There will be no further comment until the details of this incident are understood.