On Sydney's northern beaches, a small dedicated group of ocean lovers has helped halt seismic testing during the peak whale migration season.

Living Ocean, a not-for-profit Palm Beach conservation group that "promotes the awareness of human impact on the ocean", discovered a Perth-based gas company wanted to conduct seismic testing during September in waters 40 kilometres south of Newcastle.

Asset Energy planned to do seismic testing during the peak humpback whale migration season. Credit:AAP

The area of testing would have covered about 208 kilometres and was scheduled during the peak time for the southern migration of humpback whales and their calves.

Asset Energy applied to the National Offshore Petroleum Safety and Environmental Management Authority (NOPSEMA) to do the seismic testing but their application was unsuccessful and the company has been told to modify and resubmit their application.