South Sound Strategy: Marine Nearshore Habitat

Marine Nearshore Habitat

Attribute(s) Common to this Focus Area

  • Intact Feeder Bluffs (sediment supply)
  • Marine Riparian Vegetation
  • Intact Large Estuaries
  • Intact Small Estuaries
  • Eelgrass Beds
  • Herring Abundance and Distribution
  • Surf Smelt and Sand Lance Abundance and Distribution

Background

Marine nearshore habitat has long been a focus of South Sound ecosystem protection efforts and will remain so. The nearshore is the transitional zone among terrestrial, freshwater, and marine ecosystems. Many of the important and unique characteristics of Puget Sound depend upon the nearshore, including its physical complexity, high productivity, complex food webs, diverse habitats, and diversity of organisms (link). Marine nearshore habitats are some of the primary places where young salmon and steelhead find refuge, food, and passage to the sea. These important rearing, feeding, and migration areas are the result of natural processes that move sediments; provide nutrients, organic matter, and LWD from plants; and produce insects and similar marine animals (link).

The finger inlets and various islands in South Sound provide extensive sand and gravel beaches used for spawning by forage fish (i.e. surf smelt and sand lance). Because adult and juvenile Chinook rely on forage fish for a significant portion of their diet, protecting or restoring beaches is critical to salmon populations that originate in South Sound rivers as well as other rivers in the greater Puget Sound ecosystem.

Status Snapshot

  • Intact Feeder Bluffs/Sediment Supply: There are 494 individual drift cells in the South Sound. Of these, 297 contain either historic or current feeder bluffs (or both) that once provided or still provide sediment supply to shoreline beaches and nearshore habitats. Of the 400 miles of shoreline in the South Sound, approximately 120 contain some type of armoring such as bulkheads or riprap (approximately 30% of the total shoreline). Budd, Carr, and Case Inlets have the most shoreline armoring at 53%, 48%, and 43% respectively, relating directly to them also having the most markedly reduced sediment supply from feeder bluffs, as discussed above.
  • Marine Riparian Vegetation: Of the 400 miles of shoreline in South Sound, approximately 65% (260 miles) currently have intact marine riparian cover (Figure 8.1). Marine riparian habitat is most intact along Totten and Little Skookum Inlets, both sides of Pickering Passage, and around Harstine Island. The shorelines with the least marine riparian habitat include the northern end of Case Inlet, Budd Inlet, and the eastern shoreline near the cities of Steilacoom, University Place, and Tacoma.
  • Intact Large Estuaries: Large estuaries comprise approximately 18 miles of the South Sound shoreline with the Nisqually delta as the largest. The AHSS defined a large estuary as “intact” if the shoreline contains is less than 12% modifications. Four of the inlet/island groups only have 1 large intact estuary, while the other three inlet/island groups have 3 intact estuaries based on the amount of modified shoreline.
  • Intact Small/Pocket Estuaries: Small pocket estuaries comprise approximately 20 miles of the South Sound shoreline although some have been heavily modified by development, including nearshore fill and shoreline armoring. Totten & Little Skookum Inlets, Eld Inlet, and Henderson Inlet have the greatest amount of intact small estuaries while Budd Inlet has the least.
  • Eelgrass Beds: A little over 60 miles of shoreline, or 15% of the total shoreline (450 miles) supports patchy or continuous eelgrass beds, as shown in figure 8.10 and Table 8.4. Beds only occur in the north and eastern portion of the South Sound and not in the finger inlets or islands of the southern end. The Nisqually Delta front and directly adjacent areas contain some of the largest eelgrass beds in South Sound. The intertidal areas around Anderson, McNeil, and Fox Islands contain patchy eelgrass beds as annually surveyed by WDNR. In addition, the shoreline adjacent to Steilacoom and University Place supports patchy eelgrass beds as does portions of Carr and Case Inlets. Very little (~6 miles) continuous eelgrass bed has been documented in the South Sound.
  • Herring Abundance and Distribution: WDFW has tracked the spawning biomass of the Squaxin Pass herring population annually since 1973. In 2015, the biomass was 324 tons. The average amount over the period of record is 710 tons, with the highest year recorded as 2002 (3,150 tons) and the lowest year in 1997 (20 tons). Hammersley Inlet & Oakland Bay Inlet/Island Group has the most herring spawning area (11%) while Carr Inlet and the Harstine Island and McNeil Inlet/Island Groups have the greatest number of herring holding areas. Several Inlet/Island Groups do not contain herring spawning or holding areas including Budd Inlet, Case Inlet, and Henderson Inlet.
  • Surf Smelt and Sand Lance Abundance and Distribution: Surf smelt and sand lance spawning has been documented across the South Sound (shown in Table 8.6), with the greatest amount on the beaches of Harstine Island (24.6% for surf smelt and 6.2% for sand lance). Overall, surf smelt spawning areas are more abundant than sand lance with over 100 documented miles versus 15 miles, respectively.

Key Pressures

  • Conversion of land from natural cover to housing and urban areas
  • Conversion of land from natural cover to commercial and industrial areas
  • Roads & railroads (including culverts)
  • Dams
  • Marine levees, floodgates, tide gates, armoring and other shoreline alterations
  • Marine shoreline infrastructure
  • Tourism & recreation areas

Targets

Intact Feeder Bluffs/Sediment Supply:

  1. Protect all intact shoreline throughout South Sound, 278.6 miles, of which 201.7 miles are in the areas identified as a priority in the Coastal Catchment Assessment and/or the NPST for Juvenile Salmon
  2. Restore 73.1 miles of modified shoreline in the areas identified as a priority in the Coastal Catchment Assessment and/or the NPST for Juvenile

Marine Riparian Vegetation

  1. Protect all intact marine riparian habitat throughout South Sound, 260 miles, of which 170.3 miles are in the areas identified as a priority in the Coastal Catchment Assessment and/or the NPST for Juvenile Salmon
  2. Restore 36.6 miles of degraded marine riparian habitat in the areas identified as a priority in the Coastal Catchment Assessment and/or the NPST for Juvenile Salmon.

Intact Large Estuaries:

  1. Protect all intact large estuary shoreline throughout South Sound, 15.7 miles, of which 15.5 miles are in the areas identified as a priority in the Coastal Catchment Assessment and/or the NPST for Juvenile Salmon
  2. Restore 1.5 miles of degraded large estuary habitat in the areas identified as a priority in the Squaxin Island Tribe NPST for Juvenile Salmon.

Intact Small/Pocket Estuaries:

  1. Protect all intact small pocket estuary shoreline throughout South Sound, 85 miles, of which 82.4 miles are in the areas identified as a priority in the Coastal Catchment Assessment and/or the NPST for Juvenile Salmon
  2. Restore 14.3 miles of degraded small estuary habitat in the areas identified as a priority in the Coastal Catchment Assessment and/or the NPST for Juvenile Salmon.

Eelgrass Beds: Eelgrass beds are expected to benefit from actions to improve water quality and marine nearshore habitat. A target for eelgrass beds may be set in the future.Herring Abundance and Distribution: AHSS is not confident that we could directly attribute changes in Squaxin Pass herring abundance and distribution to local actions and are therefore not setting a target at this time. A target may be set in the future.

Surf Smelt and Sand Lance Abundance and Distribution: Surf smelt and sand lance are expected to benefit from actions to improve marine nearshore habitat. A target for surf smelt and sand lance may be set in the future.Salmon.

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