Police are yet to interview the young men who posted photos of themselves on Facebook holding two dead eels.
Willowbank Wildlife Reserve was alerted to the photo after four of the 70-year-old eels were found dead, including two that had been stabbed at Smacks Creek on November 12.
The photo showed the youths on the reserve's grounds with the eels hanging on the end of their spears.
Under the photo, the youths had said they did not kill the eels to eat them but because they were "bored and looking for something to do".
Senior Constable Geoff Houston said they had not yet made contact with the youths.
"We are looking at speaking to them next week. We haven't had a chance yet."
Houston said he could not yet say what charges the men might face.
Willowbank had provided police with the names of both men after seeing the image on Facebook.
Manager Dale Hedgcock said staff were being patient about the killings.
"A lot of people are saying 'what's happening to these guys', but it hasn't dropped off the police radar," he said.
Hedgcock said the staff had been "somewhat pacified" by the public response to the slaughter.
"We've had a lot of support from people coming out and saying what happened was awful. It's really made the staff realise what they do is worthwhile and justified that this is wrong."
Hedgcock said the reserve hoped to develop an eel sanctuary on the Styx River to preserve the "threatened species".
Staff wanted "something good" to come out of the incident.
He said the sanctuary proposal was a joint initiative between the reserve and the Styx Living Laboratory Trust.
The Department of Conservation supported the idea, which was in the planning stage, he said.
Hedgcock said the sanctuary would include educational signs on the Styx River Reserve.
People needed to be aware that eel numbers had dwindled, Hedgcock said.
Long-finned eels were listed as a "threatened species", just like the grey spotted kiwi.
"We want something good to come out of this. We can't protect them all over the country but we can do something small. If we don't educate people, this sort of thing will continue to happen."
He also believed the catch limit of six eels per person should be lowered.
"That's a lot considering how long it takes those eels to breed."
Hedgcock said staff were devastated by the deaths as the eels were in their "safe haven", and were so used to being fed by humans they were like "pets".
"I've got no doubt the moment they saw those shadows [from the people] they would've come to the surface. They would've thought someone's got food ... It's very sad."
Staff had worked for over 10 years developing the Styx River eel display, feeding up to 80 wild eels three times a day, but now only a few remained, Hedgcock said.
"I think they will come back, it's just going to take time."
"A lot of visitors on the weekend came in to say how sorry they were that this happened."
Among those devastated by the deaths were children at Kidsfirst Kindergarten Lincoln who wrote to The Press saying: "We feel sad because next time we go to Willowbank there will be no eels.
"Stop killing the eels because it is not nice and they are endangered and we will be very sad."
They also suggested that instead of killing eels, the youths should go tramping, fly a kite, have a swing or do some exercise.
- The Press
Have you seen rats on your property?Related story: Does Christchurch have a rat problem?