Associate Prof Liz Slooten, of the University of Otago's zoology department, said there was already a significant overlap between offshore prospecting activity and the dolphins' habitat off the coast of Otago and Canterbury.
Permits being offered under the 2015 block offer would expand that overlap, she said.
The 2015 block offer for petroleum exploration permits, announced by New Zealand Petroleum and Minerals (NZPAM) last week, opens up more than 425,000sq km to oil and gas prospecting, which is typically conducted via seismic surveys using air guns.
''One of the problems [with seismic surveys] is that, if [marine mammals] hear a loud noise and move away from that noise, then they could move into an area where there are more predators, more fishing nets, or less food for them,'' she said.
Under the 2015 block offer, permit areas for seismic surveying ''would go just into Hector's dolphin habitat''.
Hector's dolphins could hear and be affected by the seismic surveys when they were up to 100km away, Prof Slooten said, meaning even seismic testing outside the dolphins' habitats could be problematic.
The Department of Conservation has a code of conduct that mandates several safe measures for any marine seismic activity, including having independent observers on board who look out for marine mammals and stopping seismic surveying activity temporarily following marine mammal detection.
''The code is considered to be one of the most rigorous in the world for protecting marine mammals,'' a Doc spokesman said.
According to Doc's website, the code is not mandatory and ''non-enforceable under the Marine Mammal Protection Act 1978'', although it is similar to regulations in five of New Zealand's six marine mammal reserves that are mandatory.
But Prof Slooten dismissed the code's measures as ''a feel-good exercise and a PR device''.
''It's a really low level of a detection,'' she said.
''There's obviously a huge difference between how far the noise reaches and how far observers can [detect] anything.''
Despite Hector's dolphins' capacity to be affected by seismic surveying up to 100km away, Prof Slooten said, ''after about a kilometre, there's a very low chance of hearing or seeing [a Hector's dolphin]''.
A large swath of the Otago coast is being considered for marine protection by the Southeast Marine Protection Forum, a group of community members charged with making a recommendation for how the marine area should be protected by 2016.
However, even under the strictest standards of marine protection, oil and gas prospecting is not necessarily forbidden, a forum spokeswoman said.
Special terms included in marine protection legislation ''could definitely prohibit it'', but acknowledged a clause prohibiting oil and gas activity was not standard in other marine protection areas that had already been established.
NZPAM acting national manager of petroleum David Jeaffreson said if a marine protected area was to go ahead as a result of the forum, ''any overlaps would need to be worked through as part of designing the relevant piece of legislation''.
Prof Slooten said seismic surveying ''certainly shouldn't be happening inside the habitat of an endangered species that only lives in New Zealand''.
