Lifeguards deal with such cases an average of 1722 times each year - more than the average number of rescues (1343).
The number of first-aid cases at beaches is increasing every year.
"We end up now doing more first-aid incidents than rescue incidents. Even as a lifeguard, I didn't quite realise it had got to that state," said Dr Moran, who patrols at Muriwai on the west coast.
"Our primary job is obviously still preventing people from drowning. But with easy access to the beach, [and] more people at the beach, that lifeguard becomes the first-stop-shop."
Also surprising was the number of injuries to children, Dr Moran said. Those aged under 16 accounted for 52 per cent of first-aid responses.
Lacerations and abrasions were the most common injury at 47 per cent, with marine stings next at 16 per cent and bruising at 12 per cent.
Patients were almost as likely to be walking or running before their treatment (32 per cent) as swimming (35 per cent).
In terms of the location of an injury, 32 per cent were on the foot or ankle, with three-quarters of those injuries being lacerations.
Dr Moran, who has been a lifeguard for more than 50 years, said the survey showed that first-aid training was particularly useful for lifeguards.
Parents should take the results as a reminder that keeping their kids safe at the beach extended beyond water safety, he said. "If you know that a beach is rocky or subject to litter, it might be a good idea to wear reef shoes for your kids and yourselves.
"When you know there are stingers in the water, blue bottles and so on, that you take safety precautions - either stay out of the water, or wear protective rash vests and things like that."
Any medications, including asthma inhalers, should be packed, as should a basic first-aid kit.
"Hell, I'm a parent myself," Dr Moran said. "When I go to the beach I just shove everything I can think of in the car, but often not the things I necessarily need for first aid."
The research, which was presented at the World Drowning Prevention Conference in Potsdam, Germany, found 18 per cent of first-aid incidents were severe enough to require more medical attention.
About 4000 volunteer lifeguards will spend more than 200,000 hours at some 80 beaches this season.