The Cook Islands police commissioner, Pira Wichman, says a co-operation pact with Samoa on fishing surveillance is a major new deterrent to poachers.
The agreement means the Cook Islands can ask Samoa to patrol its exclusive economic zone, and vice versa.
Commissioner Wichman says this benefits both nations because of the difficulty in finding illegal fishing vessels given the huge size of the maritime zones.
"I will send their message out to the illegal poachers, illegal fishing boats, that are in our waters, in Samoa waters, saying, look, this is a demonstration of the law enforcement agencies working together... watch out, because we're coming out there, and we're most determined that we're going to stop the illegal trade of illegal fishing in our waters, and that's exactly what we're going to do."
Commissioner Wichman says the Cook Islands has experience in catching illegal fishing vessels, having seized two boats in two years.