EPA's Vessel General Permit and Small Vessel General

quality associated with contamination by pesticides, heavy metals, and industrial contaminants;
aquaculture and incidental or accidental introductions; and the Gulf sturgeon’s slow growth and
late maturation (56 Federal Register 49653).
Dependence on Waters of the United States
Gulf sturgeon are anadromous and spend the major part of a year in freshwater, migrating to
saltwater in the fall. The best river habitat for gulf sturgeon are long, spring-fed free-flowing
rivers. Steep banks and a hard bottom with an average water temperature of 60 to 72°F are also
characteristic of rivers where sturgeon inhabit. Sturgeon occupy the river bottom downstream of
springs where they seek thermal refuge during hot summer days.
Empirical studies of relationships between sturgeon and water quality have demonstrated that
sturgeon populations are limited by low levels of dissolved oxygen levels and high temperatures
in the rivers, streams, and estuaries they occupy; juvenile anadromous sturgeon also depend on
the freshwater-brackish interface in the tidal portion of rivers for nursery areas. Siberian sturgeon
(Acipenser baeri), for example, appear to have a preferred temperature range between 17.2 and
21.5° C and preferred dissolved oxygen levels between 5.9 and 13.2 mg/l (Khakimullin 1987).
White sturgeon in the Bliss Reach of the Snake River (upstream of Brownlee Reservoir) were
caught in water with temperatures between 10 and 22°C and dissolved oxygen levels between 8
and 16 mg/l (Lepla and Chandler 1995). Temperatures of 26°C and dissolved oxygen levels of 3
mg/l killed all juvenile Atlantic sturgeon (Acipenser oxyrinchus) in five out of six replicates
(Secor and Gunderson 1997) and dissolved oxygen levels of 2.5 mg/l killed all 25-day old
shortnose sturgeon (Acipenser brevirostrum), 96 percent of 32-day old shortnose sturgeon, 86
percent of all 64-day old sturgeon, and 12 percent of 104- to 310-day old shortnose sturgeon
(Jenkins et al. 1993).
Critical Habitat
Critical habitat was designed for Gulf sturgeon in 2003 (68 Federal Register 13370). The
designation encompasses 14 sites in Louisiana, Mississippi, Alabama, and Florida. The primary
constituent elements essential for the conservation of Gulf sturgeon are those habitat components
that support feeding, resting, and sheltering, reproduction, migration, and physical features
necessary for maintaining the natural processes that support these habitat components. The
primary constituent elements include:
1. Abundant prey items within riverine habitats for larval and juvenile life stages, and
within estuarine and marine habitats and substrates for juvenile, subadult, and adult life
stages;
2. Riverine spawning sites with substrates suitable for egg deposition and development,
such as limestone outcrops and cut limestone banks, bedrock, large gravel or cobble beds,
marl, soapstone or hard clay;
3. Riverine aggregation areas, also referred to as resting, holding, and staging areas, used by
adult, subadult, and/or juveniles, generally, but not always, located in holes below normal
riverbed depths, believed necessary for minimizing energy expenditures during fresh
water residency and possibly for osmoregulatory functions;
4. A flow regime (i.e,. the magnitude, frequency, duration, seasonality, and rate-of-change
of fresh water discharge over time) necessary for normal behavior, growth, and survival
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