There was one question in the public mind when wildlife officers made the decision to euthanase the baby dolphin found alone and stranded in the Mandurah Estuary, south of Perth, on the weekend.

Why did it have to die?

Why couldn't it be hand-fed and raised by people? Why couldn't it just be released into deeper water to find its mother? Why not wait another day or two to see if its mother returns?

For the volunteers who cared for the two-month-old calf for 24 hours, holding it in a sling in a hastily-made sea pen hundreds of metres offshore, the answers to those questions are complicated and problematic.

Leading the volunteers from the Mandurah Dolphin Volunteer Rescue Group was Sally Kirby, a 20-year veteran of responding to dolphin strandings.

She knows the elation of returning healthy dolphins to the open water, and the heartbreak like she experienced on Sunday, as the helpless, distressed and exhausted calf had to be put down.

When the baby dolphin was found on Saturday morning, it was wedged in ankle-deep water, only 10 metres from shore, in Robert Bay.

The shallow water stretches for more than 500 metres in every direction, and it is still not clear how it made its way into the shallows.

But the real problem for rescuers was the dolphin's age.

Dolphin needed mother for survival

Estimated at two months, and just 1.4 metres in length, the animal was helpless without its mother.

Without teeth, it could not feed. And without up to two years of guidance from an adult, it could not learn how to survive in the wild.

"It's not a matter of just picking it up and putting it back into the deeper water. It could not survive without its mother," Ms Kirby said.

"It certainly could not be left where it was. It would have died a very slow and painful death."

The only viable option was to quickly find the mother and reunite it with the baby.

Sorry, this video has expired Baby dolphin stranded near Mandurah

The volunteers moved the calf to knee-deep water about 300 metres from the shore, in the hope it would carry the young dolphin's cries and attract the missing adult.

Using boats and a jet ski, Ms Kirby and her team searched the estuary on Saturday but could not find the mother.

This radically narrowed the options for volunteers and the Department of Parks and Wildlife (DPAW).

Ms Kirby said with a dolphin of this age, just releasing it in the hope it would find its mother was never a viable choice.

'It's not simple'

Some time ago, the group rescued an eight-month-old dolphin from the upper reaches of the Serpentine River.

The dolphin calf became increasingly distressed after efforts to find its mother failed. ( ABC News: Andrew O'Connor )

In that case the dolphin was sufficiently mature, healthy and trained by its parent and it eventually found its way back to its mother.

But even then, it was stranded and rescued twice more before reaching the safety of its mother's side five days later.

"There's so many factors that you really have to spend some time thinking about and it's just not as simple as putting a little baby like that back," she said.

With no sightings of the mother, by mid-morning on Sunday, DPAW officer Matt Swan decided, on veterinary advice, the most humane solution was to euthanase the dolphin.

Ms Kirby said even with the sad outcome, the rescue effort provided useful lessons in how to strengthen the ability to save stranded dolphins in the future.

Limited resources 'hampered rescue effort'

The volunteer group has limited resources and equipment, including only one sling to carry adult dolphins.

Ms Kirby said a sling for young dolphins, an inflatable pontoon for shifting dolphins across the shallow waters of the estuary, and even a trailer to move them by road, would greatly enhance the group's capability to assist DPAW.

She said the purchase of suction cup trackers could provide an alternative to an early decision to euthanase a young dolphin.

"If we'd had money for a suction cup, perhaps we would have had more confidence in releasing the baby and then it could have been tracked to make sure it was going along OK," she said.

Premier Mark McGowan has praised the volunteer rescuers saying it was "heartening that people actually really care".

Environment Minister Stephen Dawson also paid tribute to the efforts of volunteers and said he would consider their ideas for strengthening the rescue capability.

"I'm very happy to meet with that group and have a conversation with them and work out whether there is any possibility of getting them some resources," he said.

"It was tragic to read about the dolphin having to be euthanased but I'm definitely happy to work with those people to see what can be done."