The National Marine Fisheries Service (NMFS) recently completed its review of the status of eastern North Pacific harbor seals (Phoca vitulina richardii) in Iliamna Lake, Alaska, a large freshwater lake in Alaska connected to the Bristol Bay region of the Bering Sea. NMFS concluded (pdf) that the seals do not constitute a species, subspecies, or distinct population segment (DPS) under the Endangered Species Act (ESA), and, thus, listing the harbor seals in Iliamna Lake as threatened or endangered is not warranted.

The Center for Biological Diversity (CDB) submitted a petition to list the Iliamna Lake harbor seals as a threatened or endangered species on November 19, 2012, asserting that they constitute a DPS of Pacific harbor seals. On May 17, 2013, NMFS found that CBD’s petition presented substantial information indicating that listing the Iliamna Lake harbor seals under the ESA may be warranted.

To qualify as a DPS, two criteria must be met: (1) the population segment must be discrete in relation to the remainder of the species (or subspecies) to which it belongs; and (2) the population segment must be significant to the remainder of the species (or subspecies) to which it belongs. Thus, to constitute a DPS, the Iliamna Lake harbor seals would need to be both discrete from and significant to the eastern North Pacific species of harbor seals (P. v. richardii).

After reviewing the best available information, NMFS determined that the Iliamna Lake harbor seals meet the criteria for discreteness but not significance. Specifically, genetic sampling strongly indicates that the seals from Iliamna Lake likely constitute a resident population that is genetically differentiated from harbor seals in eastern Bristol Bay, and thus meet the criteria for consideration as a discrete entity. However, the best available information fails to demonstrate that the Iliamna Lake harbor seals are a significant population warranting classification as a DPS. The information fails to demonstrate that the population is biologically or ecologically important to the species as a whole, and that loss of the Iliamna Lake population would be detrimental to the species or constitute a gap in the range of the species. Because NMFS found that the Iliamna Lake population of harbor seals was not “significant,” the seals do not qualify as a DPS and are not eligible for listing under the ESA.