The reward — which has risen from an initial $5000 — expires in relation to one of the deaths on September 20.
The New Zealand Sea Lion Trust (NZSLT) offered the $5000 reward after a sea lion pup was found dead from shotgun wounds in the Catlins area on September 22 last year.
Two weeks later, Jade, the pup’s mother, was also found shot dead.
Public outrage at the killings led to the award growing to $50,000, funded by groups and private individuals.
A necropsy also found a third sea lion may have been stabbed at Waipati Beach on November 11 last year and left to die.
When Doc rangers were notified about the wounded sea lion, her injuries were found to be so severe she had to be euthanised.
The reward also applies for information relating to that death, which will expire in early November, as the statute of limitations on any prosecutions under the Wildlife Act is one year.
NZSLT co-chairman Shaun McConkey said yesterday only general information had been received in relation to possible culprits.
"We’ve had a couple of inquiries from people regarding historic situations, concerning ‘people who don’t like sea lions’.
"That can certainly give authorities someone to look at, but it’s not definitive, and not evidence ..."
He said the failure to identify those responsible a month out from deadline was "disappointing", although the rewards and media coverage had sent a clear message to possible future perpetrators.
"Obviously we would like to have identified and prosecuted those responsible, but we remain extremely grateful to all those who have come forward in support, and especially those groups and individuals who have put up such a significant reward.
"The reward sends a clear message that people simply won’t stand for this behaviour, and are watching. At some point, those responsible will be caught."
Anyone with information relating to any of the three sea lion deaths can make contact, in full confidentiality, at info@sealiontrust.org.nz.
