Despite a battery of tests, little progress has been made in discovering the cause of a January gull die-off in Tacoma.
Whatever killed or sickened as many as 50 gulls hasn’t been found, but it mostly likely poses no risk to human health, the state Department of Fish and Wildlife said Thursday.
The agency said more tests are underway.
“Based on what we know so far, water pollution or contamination is highly unlikely and there is little or no risk to human health,” Dr. Katie Haman said in a statement Thursday.
Haman, a Fish and Wildlife veterinarian, is part of the team investigating the incident.
The gulls, some dead and others paralyzed from the neck down, were first noticed by Port of Tacoma workers Jan. 22.
Others were later found around Commencement Bay and as far north as Kent.
All were glaucous-winged gulls or glaucous-winged/western gull hybrids, according to Fish and Wildlife.
The last sick or dead birds were reported Feb. 5.
Some of the sick gulls were taken to wildlife rehabilitation centers in the Puget Sound area. Out of those, 20 are alive and improving.
Initial lab results have ruled out avian influenza virus and avian cholera, Fish and Wildlife said.
While lead poisoning was eliminated as well, testing for other heavy metals is ongoing.
Marine algal toxins — such as the well-known paralytic shellfish poisoning — are unlikely because only gulls were affected. However, testing for those poisons continues.
Final lab results, including testing for viruses and botulism toxin, are expected later in February.