Cr Peter Moran said the cockle grabbing has spread around the entire lake since the start of spring.

"They're back out in force," Cr Moran said.

"I've heard reports of significant numbers of them in various parts of the lake, including the northern section over around Berkeley but especially noticeable for me down around the southern areas, from Oak Flats through to the entrance to the lake."

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Cockle collecting has been an issue at Lake Illawarra for several years as local residents report seeing people wading out in the water taking more than the 50 allowed under NSW regulations.

"I grew up at Oak Flats in a house on the lake and you never saw cockle collectors at that stage," Cr Moran said.

"There was a significant number of people who used to go prawning but to my recollection cockle collecting was unknown. So this is actually an issue that has arisen in the last couple of years."

Cr Moran is planning to table a motion at the next Shellharbour council meeting on September 29 asking council to write to the Department of Primary Industries requesting a lowering of the bag limit from 50 to 20, in line with those of similar molluscs.

"There's very little scientific evidence to suggest that either it does or doesn't harm the health of the lake in having this number of cockles extracted from the lake's ecosystem," Cr Moran said.

"So let's step things down a little bit and one way of doing that is reducing the bag limits until we find out whether it has a deleterious impact on the health of the lake."

The bag limit of 20 was also chosen because it seemed like an amount someone might actually eat.

"It's a smallish mollusc," he said, "the fleshy part that is eaten is a little smaller than an oyster. Fifty seems to be a lot for people to sit down and eat in one sitting."

A Department of Primary Industries (DPI) spokeswoman would not say whether they would support a lower bag limit for cockles.

She said DPI Fisheries officers regularly patrolled Lake Illawarra.

"There are 11 NSW DPI Fisheries officers conducting fisheries compliance patrols across the Illawarra and Shoalhaven areas, including five officers who are based at Port Kembla," she said.

"To help address the illegal shellfish collecting problem NSW DPI Fisheries has assembled a special mobile squad of experienced fisheries officers to patrol the area between Newcastle and Wollongong."

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