The death of a pelican at Shellharbour in recent weeks is believed to be the result of a deliberate attack.

Australian Seabird Rescue volunteer Kirsten Hort said people spending time in and around the region's waterways and beaches needed to be aware that they were sharing the area with a variety of seabirds, shorebirds and other marine wildlife.

"In many cases the festive season does not bring a lot of joy to our feathered friends and a significant number of birds are injured due to unsafe fishing practices and polluted waterways."

Mrs Hort said the main injuries to birds, especially pelicans, was getting hooked or entangled in discarded fishing gear.

She urged people to think carefully about where they fished and to not leave any discarded tackle and rubbish behind.

Mrs Hort said while most injury cases to bird and sealife arose through human ignorance or carelessness, sometimes the animals were injured or died in a more sinister way.

Rescuers believe an injured pelican found by the Shellharbour boat ramp a couple of weeks ago was the victim of a deliberate attack.

Passers-by found the animal struggling to walk along the boat ramp shortly after 7pm on December 13, suffering from an apparent gunshot or slingshot wound to its gular pouch, below the beak.

They rang the Australian Seabird Rescue hotline but by the time volunteers arrived the pelican had died.

"We spend a great deal of time rescuing and rehabilitating these wonderful creatures and this is a real blow to the organisation," Mrs Hort said.

"The incident is horrendous and distressful and obviously we cannot comprehend who would perform such a ruthless act. We want these people to be brought to justice."

The injury was also reported to Lake Illawarra police.

"We are hoping anyone who may have any further information or knowledge of this event to report it to the police," Mrs Hort said.