June 12, 2013 — In February 2012, NOAA Fisheries listed five distinct population segments of Atlantic sturgeon under the Endangered Species Act (ESA). The Gulf of Maine population was listed as threatened and the New York Bight, Chesapeake Bay, Carolina and South Atlantic populations were listed as endangered. Listing determinations under the ESA must be made based on the best scientific and commercial data available at the time.
The Atlantic sturgeon listing determination was based primarily on an analysis of the ongoing and future threats to the species because there were no overall population estimates available. In the listing determination, we used estimates of spawning adults in the Hudson and Altamaha Rivers, which indicated that these populations were quite low (867 total adults in the Hudson and 343 spawning adults per year in the Altamaha). The primary threats to the species identified in the listing determination were incidental catch in fisheries, vessel strikes, water quality and quantity, and dredging.
Since the listing, we have been working on obtaining more comprehensive population estimates for the species. These population estimates are useful for recovery planning and to complete required consultations under the ESA. Whenever a federal or state agency conducts an activity that could potentially impact a species listed as threatened or endangered under the ESA that is managed by NOAA Fisheries, they are required to consult with our agency so we can provide recommendations to help mitigate impacts on the species.
New Population Estimates
At our request, the Northeast Fisheries Science Center developed a new population estimate for the Atlantic sturgeon that are mostly living in the ocean, rather than rivers, using a new model. The resulting population estimate for oceanic Atlantic sturgeon was between about 165,400 and 744,600 fish. This does not include young fish that have not yet left the rivers in which they were born or Atlantic sturgeon that occur outside of the sampled area (e.g., in Canadian waters or south of Cape Hatteras).
Given time sensitivities and the uncertainty associated with the new estimates, we used another estimate that the Center generated from Northeast Area Monitoring and Assessment Program (NEAMAP) data to complete a “batch” biological opinion for 7 Northeast Fisheries. Using these NEAMAP data, the Center calculated ocean population estimates, which entail fewer assumptions about Atlantic sturgeon than the ASPI model. The minimum biomass estimate from this approach is approximately 67,800 oceanic Atlantic sturgeon. This is a conservative estimate of fish in the majority of the area affected by the seven Northeast Fisheries.
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