The Sea Watch Foundation is celebrating 10 years of the national whale and dolphin survey.
New Quay in Ceredigion is said to have one of the largest populations of bottle nose dolphins in the UK.
Dolphin watchers are recording sightings, and this year’s figures are starting to be analysed.
Paula Redmond, who is taking part in the annual survey, said it helped experts understand the ecology of the water.
“The waters in Cardigan Bay are very clean so this is probably why the biggest population is here.
“It’s to keep an eye on things because if anything changes with the dolphins as the top predators it could indicate that other things are going on, that other species are having problems.
So they’re very good indicators of what’s going on in the ecology of the water out here.”
Jonathan Evans of New Quay Boat Trips said he had seen quite a few dolphins in the area, and he was confident boats were not having a negative effect on them.
“It’s a good sign for the marine environment too, because it shows there are enough fish in the sea for the dolphins to eat,” he said.
The largest group of bottle nose dolphins reported in Cardigan Bay was on Sunday morning near Anglesey, when a regular Seawatch observer Dave Powell counted 44.
Elsewhere sightings have been reported from Cardigan Island, Mwnt, Ynys Lochtyn, Bird’s Rock in New Quay and New Quay harbour off Ceredigion.
Thirty miles west of Caernarfon in Gwynedd a pod of 30 common dolphin was also spotted.
The Sea Watch Foundation’s sightings officer, Danielle Gibas, said: “We are delighted that the weather, although changeable meant that people were able to get out and about and send in sightings.
“We are still awaiting and inputting sightings, particularly from boat operators out to sea, and it is not too late to email us on firstname.lastname@example.org”