Preliminary results of samples taken from dozens of dead fish found in a tide pool on Lehua Island are “inconclusive” as to whether rat poison killed the fish, according to the state Department of Land and Natural Resources.

The state conducted a rat eradication project on the island located near Niihau in August and September in an effort to create a bird sanctuary for threatened and endangered birds. Three rounds of rat bait containing diphacinone were scattered on the island via helicopter.

After the second application, the state learned of the dead fish after videos were posted on social media. About 45 dead mullet were collected from a tide pool on the northern side Lehua Island and sent to the state Department of Agriculture and the U.S. Department of Agriculture Animal and Plant Health Inspection Service’s National Wildlife Research Center to be analyzed.

According to DLNR, both the state and the research center show samples were “‘in a severely degraded condition,’ making it impossible to determine whether the mullet-type fish were affected by diphacinone or died due to other factors associated with being trapped in tide pools; such as high temperature or limited oxygen.”

A final report is expected to be compiled that will include results of an environmental analysis of samples collected before and after the aerial bait applications.