Critical Habitat

Under section 3 of the ESA (16 U.S.C. 1533(b)(2)), critical habitat is defined as the specific areas supporting those physical and biological features that are essential for the conservation of the species and that may require special management considerations or protection.  Section 4 of the ESA and regulations at 50 CFR 424.12(a) require the designation of critical habitat on the basis of the best scientific data available.

The necessary physical and biological features constituting critical habitat were identified and critical habitat was designated for the GOM DPS of Atlantic salmon by NOAA on June 19, 2009, (74 FR 29300; figure 8) and later revised (74 FR 39903). 

The essential physical and biological features for critical habitat are

A.  Spawning and rearing

1.   Deep, oxygenated pools and cover (e.g., boulders, woody debris, vegetation) near freshwater spawning sites necessary to support adult migrants during the summer while they await spawning in the fall.

2.   Freshwater spawning sites that contain clean, permeable gravel and cobble substrate with oxygenated water and cool water temperatures to support spawning activity, egg incubation, and larval development.

3.   Freshwater spawning and rearing sites with clean, permeable gravel and cobble substrate with oxygenated water and cool water temperatures to support emergence, territorial development, and feeding activities of Atlantic salmon fry.

4.   Freshwater rearing sites with space to accommodate growth and survival of Atlantic salmon parr.

5.   Freshwater rearing sites with a combination of river, stream, and lake habitats that accommodate Atlantic salmon parrs’ ability to occupy many niches and maximize parr production.

6.   Freshwater rearing sites with cool, oxygenated water to support growth and survival of Atlantic salmon parr. 

7.   Freshwater rearing sites with diverse food resources to support growth and survival of Atlantic salmon parr.

 B.  Migration

1.   Freshwater and estuary migratory sites free of physical and biological barriers that delay or prevent access for adult salmon seeking spawning grounds needed to upport recovered populations.

2.   Freshwater and estuary migration sites with pool, lake, and instream habitat that provide cool, oxygenated water, and cover items (e.g., boulders, woody debris, vegetation) to serve as temporary holding and resting areas during upstream migration of adult salmon.

3.  Freshwater and estuary migration sites with abundant, diverse native fish communities to serve as a protective buffer against predation.

4.   Freshwater and estuary migration sites free of physical and biological barriers that delay or prevent emigration of smolts to the marine environment.

5.   Freshwater and estuary migration sites with sufficiently cool water temperatures and water flows that coincide with diurnal cues to stimulate smolt migration.

6.   Freshwater migration sites with water chemistry needed to support sea water adaptation of smolts.

Figure 5.  Critical habitat watershed boundaries in the Gulf of Maine DPS as defined in the 2009 critical habitat rule.

These freshwater features provide habitat requirements for the growth and survival of all freshwater stages of Atlantic salmon and illustrate the complexity of habitat required by Atlantic salmon.  Determining the exact amounts and interspersion of each feature at the macro scale necessary for self-sustaining populations is currently not possible.

The location and features of physical and biological features of marine habitat essential for the conservation of the GOM DPS have not been fully identified.  Unlike some species of Pacific salmonids that use nearshore marine environments for juvenile feeding and growth, Atlantic salmon migrate through the nearshore marine areas quickly during May and early June. Therefore, marine critical habitat was not identified, and the types of management considerations or protections necessary to protect the physical and biological features during the migration period were also not identified (74 FR 29300).  Although critical habitat cannot be accurately identified in marine areas, feeding areas in the North Atlantic and the migration corridors between these feeding areas and salmon’s natal rivers are critically important to the species’ continued survival and recovery. 

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