Police are investigating after 300 ewes were reported stolen from a farm in Kurow.
The thefts are believed to have taken place in the past two months.
Kurow police constable Craig Bennett said the large quantity of stock taken would indicate that some form of stock truck or truck and trailer unit had been used in the operation.
The isolated location of the property would require the offender to have some local knowledge and experience with farming or stock handling to deal with such a large number, Mr Bennett said.
The thefts were reported after the farmer conducted a pre-lambing count of his stock and discovered about 300 ewes were missing. He had last counted the sheep in autumn, about two months earlier.
Mr Bennett believed the thefts may have occurred on several occasions.
"It would take at least two large stock-truck movements to take that many," he said.
The sheer size of some farming operations in the area made security difficult, but this recent theft served as a reminder to everyone to secure their property and to be aware of suspicious behaviour.
North Otago Federated Farmers president Richard Strowger said stock thefts were an ongoing issue in the region.
Such thefts were largely under-reported considering the value of ewes, which he believed could fetch between $160 to $200 a head.
"They are worth a lot of money. When one or two go missing, it's because someone wants to eat it, but with 300, it's a good cashflow."
"Then you've got to take into account whether they are in lamb and the wool on their back."
Regular stock tallies when shearing, drenching and tailing were important to keep track of numbers and enable thieves to be tracked down quickly.
Mr Strowger said he would like to see larger fines for stock thefts, to discourage it.
Mr Bennett warned farmers to remain vigilant when it came to their own and neighbour's properties, with Waitaki police approaching their busiest time of year for offending.
"Waitaki police are concerned that thefts from farms are on the rise, especially fuel thefts, stock thefts and scrap metal," he said.
"It is also the start of the cannabis-growing season, so please be aware of people accessing farm properties. As the weather gets warmer, we start to see an increase in these type of offences."
And in warmer temperatures, people tended to become more relaxed with security, making it easier for opportunist burglars, he said.
Anyone who has seen suspicious truck movements in the Danseys Pass area in the past two months should contact Kurow police on 03 436 0807.
Kurow police constable Craig Bennett's tips for reducing crime in rural areas
1. Secure farm buildings and fuel tanks when not in use and move valuable property to locked buildings.
2. Install sensor lights or timer lights near buildings and sheds.
3. Place sheep dogs near buildings or fuel tanks.
4. Display signs on gates to instruct people to report to the main house on arrival and install main-gate alarms.
5. Cash in any scrap metal; do not leave it lying around where people can see it.
6. Record serial numbers of valuable tools and mark them with with an identifier that can be traced to you. Visit the police website www.snap.org.nz (Serial Number Action Partnership) to list details of important items in a secure account, at no charge.
7. Take the keys out of vehicles when they are not being used.
8. Lock away all firearms and hazardous chemicals when not in use.
9. If you need to leave machinery out in a paddock, lock it and leave it where it is, in plain sight from the road.
10. Check who you employ, check their references, Google them, ask their permission to do a criminal-history check. Application forms are available at www.justice.govt.nz
11. Get to know your neighbours and discuss what you would do in case of an emergency.
12. Let your local police know if you're heading away for any extended time, as well as your neighbours.
13. Keep an eye on who is out and about. If you note anyone acting suspiciously, then note vehicle details, description, activity and let police know.
14. If you're going to investigate something suspicious let someone - your wife, husband, neighbour or police - know and take your cellphone with you.
15. Think about your own safety and the safety of others first. If there is an intruder on your property, call the police and do not take the law into your own hands.
16. No matter how insignificant, report any and all crime to police. You will never be criticised for wasting police time - because you are not. You may well be helping police establish a pattern of offending. They cannot patrol high-risk areas if they do not know where they are.