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DREDGING SUMMIT & EXPO ’18 PROCEEDINGS

ESSENTIAL FISH CONSIDERATIONS FOR DREDGE OPERATIONS: MITIGATION MEASURES AND CASE STUDIES FROM ALASKA

S. Kelly1 and L. Ames2 ABSTRACT Dredging operations and the placement of dredge 'spoils' in Alaska typically occur within identified as Essential Fish Habitat (EFH). EFH is defined as those waters and substrates necessary for roughly 60 species of shellfish, , , and groundfish to complete their life cycles. EFH conservation and is required under the Magnuson-Stevens Fishery Conservation and Management Act (MSA). Dredging can adversely affect EFH by reducing the quality and/or quantity of EFH. If adverse effects are determined to be likely, EFH Consultations are required. NOAA Fisheries is required to provide conservation recommendations to Federal and state agencies regarding any action that would adversely affect EFH. Mitigation measures are recommended actions that minimize adverse effects or encourage the conservation and enhancement of EFH. This talk will focus on two important fishery resources, Red King Crab and Pacific salmon. Each species has a unique life history and their use of different habitat types vary greatly throughout development and recruitment. The adverse effects of dredging vary by life stage, and the vulnerable life stages must especially be considered when dredging or disposing of dredge spoils within EFH. Many factors should be considered when planning a dredging project that could affect EFH, including type of dredging equipment, current strength, temperature, substrate type, timing, and other factors in order to develop appropriate mitigation measures. A full description of potential adverse impacts and recommended conservation measures for EFH during dredging activities can be found in the NOAA Technical Memorandum Impacts to Essential Fish Habitat from Non-Fishing Activities in Alaska, May 2017.

KEYWORDS Dredging, beneficial uses, Essential Fish Habitat, dredged material disposal, contaminated , conservation, management, INTRODUCTION Management of Essential Fish Habitat (EFH) is required by the Magnuson-Stevens Act (16 U.S.C. 1801 et seq) as first authorized by the Sustainable Fisheries Act, signed into law on October 11, 1996. It mandates that the Secretary of Commerce (Secretary) shall establish guidelines by regulation to assist the Regional Fishery Management Councils (Councils) and the National Marine Fisheries (NMFS) to describe and identify EFH in each Fishery Management Plan (FMP). These descriptions must include adverse impacts on such habitat and proposed actions to conserve and enhance such habitat. EFH regulations (67 FR 2343, January 17, 2002) established a process for Councils to identify and describe EFH, including adverse impacts to that habitat, per the requirements of the Magnuson-Stevens Act.

The Magnuson-Stevens Act also requires that the Secretary, in consultation with stakeholders, provide each Council with recommendations and information regarding each fishery under that Council’s authority to assist it to identify EFH, the adverse impacts on that habitat, and actions that should be considered to conserve and enhance that habitat. These regulations established procedures to carry out this mandate. In addition, the Magnuson-Stevens Act requires that Federal action agencies consult with the Secretary on any activity authorized, funded, or undertaken, or proposed to be authorized, funded, or undertaken, that may adversely affect EFH. The Secretary must respond with recommendations for measures to conserve EFH. Dredging is

1 Fishery Management Specialist, National Marine Fisheries Service Alaska Region, 222 West 7th Ave, Anchorage, Alaska, 99513, USA, T: 907-271-5195, Email: [email protected]. 2 Resource Specialist, National Marine Fisheries Service Alaska Region, 222 West 7th Ave, Anchorage, Alaska, 99513, USA, T: 907-271-5002, Email: [email protected].

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one such activity that requires consultation; the Federal action agency on most Federal dredging projects is the US Army Corps of Engineers (USACE).

The Magnuson-Stevens Act expands requirements for habitat sections of FMPs and requires consultation between the Secretary and Federal and state agencies on activities that may adversely impact EFH for those species managed under the Act. It also requires the Federal action agency (e.g. USACE) to respond to comments and recommendations made by the Secretary and Councils. For the purpose of consultation on activities that may adversely affect EFH, the description of EFH included in the FMP is determinative of the limits of EFH; however, mapping of EFH is required by the regulations to assist the public and affected parties to learn where EFH is generally located. EFH descriptions and maps must be revisited every 5 years as part of an EFH Review to incorporate the best available science, due to data gaps and the dynamic nature of physical and biological habitat characteristics. More information on EFH descriptions and maps in Alaska can be found at https://alaskafisheries.noaa.gov/habitat/efh.

The Fish and Wildlife Coordination Act (FWCA) provides a mechanism for the Secretary to comment to other Federal agencies on activities affecting any living marine resources. Under the FWCA, Federal agencies are required to consult with the Secretary on habitat impacts from water development projects. The Secretary is not, however, required to consult with Federal agencies on all activities that may adversely affect habitat of managed species, nor are agencies required to respond to Secretarial comments under the FWCA. The FWCA allows the Secretary to comment and make recommendations on Federal activities that may adversely affect living marine resources and their habitat, even if such habitat is not identified as EFH.

The Endangered Species Act (ESA) definition of ‘‘critical habitat’’ to describe habitats under its authority includes areas occupied by the species at the time of listing, as well as those unoccupied areas that are deemed ‘‘essential for the conservation of a species.’’ The EFH regulations specify that, for species listed under ESA, EFH will always include critical habitat. EFH may be broader than critical habitat if restoration of historic habitat areas is feasible, and more habitat is necessary to support a sustainable fishery. Because the statutory definition of EFH includes the full life cycle of a species, including growth to maturity, EFH is broader than critical habitat where marine habitats have not been included in the identification of critical habitat (e.g., for anadromous salmonids listed under the ESA). No fish species listed as threatened or endangered under ESA originate in Alaska. A complete list of ESA-listed species can be found at http://www.nmfs.noaa.gov/pr/species/esa/listed.htm.

ESSENTIAL FISH HABITAT The Magnuson-Stevens Act defines EFH as ‘those waters and substrate necessary to fish for spawning, breeding, feeding, or growth to maturity.’ This includes associated physical, chemical, and biological properties of the aquatic areas that fish use as well as the sediment, hard bottom, structures, and associated biological . ‘Adverse effect’ means any impact that reduces quality and/or quantity of EFH. Adverse effects may include direct or indirect physical, chemical, or biological alterations of the waters or substrate and loss of, or injury to, benthic organisms, prey species and their habitat, and other ecosystem components. Adverse effects to EFH may result from actions occurring within EFH or outside EFH and may include site-specific or habitat-wide impacts, including individual, cumulative, or synergistic consequences of actions (NMFS 2017).

Many species managed under the Magnuson-Stevens Act spend some part of their life cycle in state waters (in most states 0–3 miles offshore) as well as Federal waters (generally 3–200 miles offshore). Because the statutory definition of EFH covers the entire life cycle of a species, EFH is often identified within both Federal and state waters. Therefore, the consultation provisions for activities that may adversely affect EFH may require the Secretary to consult on activities in both Federal and state waters. NMFS may comment on activities in both Federal and state waters.

Dredging and Habitat There are many mechanisms by which marine dredging can have the potential for adverse effects on EFH. Dredging can cause direct mortality of fish and damage or removal of crucial ecosystem components. Dredging-related stressors like suspended sediment, contaminated sediment, hydraulic entrainment, and

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underwater noise can directly elicit responses and affect growth and behavior of fish across all aquatic ecosystems and all life-history stages (Wenger et. al 2016).

Suspended Sediment Suspended sediment can have direct impacts on fish survival, the severity of which depends on species, life stage, concentration, and duration of exposure. Experiments with eggs and larvae of anadromous and estuarine fish in Chesapeake Bay showed that suspended sediment reduced the hatching success and survival of some species at concentrations higher than 1000 mg/l for 48-96 hours, while some species were less tolerant, exhibiting significantly reduced survival at concentrations of 100 mg/l continuously for 96 hours. (Auld et. al 1978). Other similar experiments with marine species resulted in 50% mortality rates at concentrations of 1000 mg/l for 12 hours (Isono et. al 1998). ⩾

Suspended sediment also influences fish behavior and their ability to interact with their habitat. One of the most commonly observed behaviors by fish to elevated suspended sediment is the avoidance of turbid water (Collin and Hart 2015), an effect that has been observed in juvenile Coho salmon, Arctic grayling, and Rainbow trout. (Newcombe and Jensen 1996), species that have adapted to a range of environments. A study on two species of larval reef fishes found that suspended sediment disrupts the ability of some species to respond to chemical cues from different substrate and may reduce settlement success and survival (Wenger et al. 2011). Increased exposure to suspended sediment can cause damage to gill tissue and structure (Au et al. 2004 and Hess et al. 2015), which impairs respiratory ability, nitrogenous excretion, and ion exchange (Appleby and Scaratt 1989, Au et al. 2004, Wong et al. 2013). A study of a planktivorous marine species showed declines in food acquisition, reduction in growth and body condition, and increased mortality in high sediment environments (Wenger et al. 2012). Overall, eggs and larval life stages are more susceptible to adverse effects than juveniles and adults, and the severity of impact increases with sediment concentration and duration of exposure. It is therefore important to consider the physical scope of the project (which will dictate concentration of sediment), and duration of dredging.

Dredging Noise The noise of dredging is another important factor to consider. Studies of freshwater species have shown that noise characterized by amplitude and frequency fluctuation, like that of dredging, can elicit a significant stress response (Wysocki et. al 2005). It has been hypothesized that dredging-induced sound may block or delay the migration of anadromous fishes, interrupt or impair communication, or impact foraging behavior (Reine et al. 2014). Dredging may also impede the ability of fish to hear biologically relevant sound and interfere with critical functions such as acoustic communication, predator avoidance and prey detection, and use of the ‘acoustic scene’ or soundscape to learn about the overall environment (Slabbekoorn et al. 2010). Thus, combined with effects of , dredging can elicit an avoidance response in marine fishes (Larson and Moehl 1990, McGraw and Armstrong 1990) and can drastically change how they utilize essential habitat.

Entrainment While some studies indicate that some fish species avoid dredge activity, direct mortality by entrainment is still a risk of dredging. Dredges have the potential to entrain fishes and invertebrates during all life cycle phases including adults, juveniles, larvae, and eggs. Entrainment is the direct uptake of aquatic organisms caused by the suction field generated by hydraulic dredges (e.g., hopper and cutterhead dredges). Rates of entrainment vary widely by equipment type. A study of dredging in Grays from 1978 to 1989 showed that the highest entrainment rates and numbers of species of fish were observed in hydraulic equipment, specifically hopper dredge samples (McGraw and Armstrong 1990). Maintenance dredging and marine aggregates dredging can be expected to result in a 30–70% reduction of infaunal species diversity, a 40–95% reduction in the number of individuals, and a similar reduction in the biomass of benthic communities in the dredged area (Newell et al. 1998). A gradient of impact has been suggested from low impact in dynamic areas of high natural stress such as shallow mobile to high impacts in more stable deepwater gravel environments (Emu Ltd. 2004).

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Environmental Factors to Consider Population of When assessing the possibility of adverse effects of dredging on EFH, there are several important factors to consider. First, consider the population of the dredged water. Benthic fauna are particularly vulnerable to entrainment by dredging although some mobile epibenthic and demersal species, such as , , and fish can be susceptible to entrainment as well. (McGraw and Armstrong 1990, Nightingale and Simenstad 2001). The particular population in the area will also dictate timing windows. Are there anadromous streams nearby? Are anadromous species migrating near to the dredging activity? Sedimentation and noise effects from dredging may block or delay the migration of anadromous fishes, interrupt or impair communication, impact foraging behavior (Reine et al. 2014), and elicit avoidance (Larson and Moehl 1990, McGraw and Armstrong 1990). When is the larval recruitment period for the species in the area? It is essential to implement seasonal restrictions to avoid impacts to habitat during species critical life history stages (e.g. spawning season, egg/larval development periods). Recommended seasonal windows are generally specific to regional or watershed-level environmental conditions and species requirements. Also consider the long-term effects on ecosystem makeup. Although macrobenthic communities may recover total abundance and biomass within a few month or years, their taxonomic composition and species diversity may remain different from pre-dredging to post-dredging for more than three to five years (Michel et al. 2013).

Aquatic Vegetation Dredging can also result in a direct loss of important fish habitat like seagrasses and coral. It is crucial to evaluate whether the waterway contains submerged aquatic vegetation (SAV). Seagrasses provide key ecological services, including organic carbon production and export, nutrient cycling, sediment stabilization, enhanced biodiversity, and trophic transfers to adjacent habitats (Orth et al. 2006). Studies have shown seagrass beds to be among the areas of highest primary productivity in the world (Herke and Rogers 1993, Hoss and Thayer 1993). Dredging imposes the risk of physical removal or burial of vegetation. Larger, slow- growing climax species with substantial carbohydrate reserves show greater resilience to such events than smaller opportunistic species, but the latter display much faster post-dredging recovery when water quality conditions return to their original state (Erftemeijer et. al 2006). Increased sedimentation and can interrupt photosynthesis and reduce primary productivity of the area. Avoid disposing of dredged material in wetlands, SAV, and other special aquatic sites whenever possible. Assess all options, including upland disposal sites, for the disposal of dredged materials and select disposal sites that minimize adverse effects to EFH.

Substrate Type It is also meaningful to consider the substrate type in the dredged area. Fine silt/clay particles have relatively slow settling velocities and thus are associated with prolonged sediment suspension and extensive turbidity plumes. and gravel resettle rapidly in the immediate vicinity of the dredge (Schroeder 2009). Dredging can disturb aquatic habitat by re-suspending bottom and releasing nutrients, toxic metals, hydrocarbons, hydrophobic organics, pesticides, and pathogens into the (EPA 2000, Erftemeijer and Lewis 2006). Toxic metals and organics, pathogenic microorganisms (i.e., bacteria and viruses), and parasites, notably helminthes and protozoa, may become biologically available to organisms either in the water column or through food chain processes. A statistical analysis of dredging studies found that the influence of contaminated sediments has a greater impact on fish than either suspended sediments or sounds originating from dredging (Wenger et al. 2016).

Hydrodynamic Regimes Consider the shape and hydrodynamic regimes of the waterway. Dredge location and degree of constriction may contribute to entrainment rates. Studies in the Fraser River, British Columbia showed that juvenile salmon and smelt were distributed in closer proximity to the dredge and had higher entrainment rates, while fish in the and Grays Harbor were able to disperse over a greater area as they migrate due to the expansive mouth of this river and harbor. In those locations, nonanadromous estuarine and marine demersal species were more frequently entrained than salmonids (Larson and Moehl 1990, McGraw and Armstrong 1990). Dredging may also affect hydrodynamic regimes by modifying current patterns and water circulation via alterations to substrate morphology. These alterations can cause changes in the direction or

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velocity of water flow, water circulation, or dimensions of the waterbody traditionally used by fish for food, shelter, or reproductive purposes. Altered hydrodynamics may affect estuarine circulation, including short- term (diel) and long-term (seasonal or annual) changes (Deegan and Buchsbaum 2005). Determine a reasonable background turbidity level based on regular monitoring of ambient conditions. Establish turbidity limits (percent maximum allowable exceedance above the best estimates of background turbidity). Apply mitigation measures (e.g., temporary cessation or modification of dredging or disposal) if these limits are exceeded during dredge operations (see Erftemeijer and Lewis 2006).

Other physiological and environmental factors may influence the extent of adverse effects on EFH. Current strength may affect recolonization rates; it can take up to three years in areas with strong currents and 5 to 10 years in areas with weaker currents. Water temperature may also influence recovery times. Post-dredging recovery in cold waters at high latitudes may require additional time because benthic communities can be composed of large, slow-growing species (Newell et al. 1998). Temperature as well as the bathymetry in the area can vary noise levels and frequencies from dredging activity. If possible, activities that require dredging (e.g., placement of piers, docks, marinas) should be located in deeper water or designed to minimize the need for maintenance dredging. This may help to avoid dredging in sensitive habitat areas to the maximum extent practicable.

Dredging Equipment The type of dredging equipment and specifics of the dredging process can also greatly impact the severity of adverse effects on EFH. Types of dredging equipment that elevate levels of particles increase turbidity that may reduce light penetration and lower the rate of photosynthesis for subaquatic vegetation and primary productivity of an aquatic area. If suspended sediment loads remain high, fish may suffer reduced feeding ability. Different equipment have different sound levels and frequencies. NMFS recommends to use Best Management Practices (BMPs) to limit and control the amount and extent of turbidity and sedimentation. Standard BMPs may include silt fences, coffer , and operational modifications (e.g., use of hydraulic dredge instead of mechanical dredge).

Fate of Dredged Material Lastly, project proponents must consider the fate of dredged material, both in-water and upland. Suspended material from dredging may react with dissolved oxygen in the water and result in short-term oxygen depletion to aquatic resources. Like the discharge of dredged material, the discharge of fill material to create upland areas can remove productive habitat and eliminate important habitat functions. For example, the loss of wetland habitats reduces the production of detritus, an important food source for aquatic invertebrates. Changes to wetlands can alter the uptake and release of nutrients to and from adjacent aquatic and terrestrial systems and reduce wetland vegetation, an important source of food for fish, invertebrates, and water fowl. Dredge disposal in wetlands can further hinder physiological processes in aquatic organisms (e.g., photosynthesis, respiration) because of degraded water quality and increased turbidity and sedimentation, alter hydrological dynamics including control and groundwater recharge, reduce filtration and absorption of pollutants from uplands, and alter atmospheric functions such as nitrogen and oxygen cycles (Mitsch and Gosselink 1993). In addition, the discharge of dredged materials or the use of fill material in aquatic habitats can also result in the covering or smothering existing submerged substrates, loss of habitat function, and adverse effects on benthic communities.

CASE STUDY Dredging operations in rural Alaska are of unique importance due to the dependence of the area on fishing resources for both commercial and subsistence uses as well as shipping for essential and services. Adverse impacts to EFH from dredging could impact both the communities’ regional fisheries as well as customary and traditional uses of these resources.

Location

Nome lies 125 miles (201 km) from the Bering Strait on Alaska’s Norton Sound Coast on the Seward Peninsula. This historic mining is still engaged in mining, notably by suction and backhoe dredges. Nome is also home to a vital harbor that supplies mining, oil and gas operations, and over 50 outlying

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communities. Although a local system connects many of these communities to the Nome harbor, the road network is not connected to continental road systems and the communities depend on the Nome harbor for most resources not available locally (ADCRA 2012; NMFS 2013).

The harbor at Nome sits where the discharges into Norton Sound. The harbor site is on an exposed stretch of low-relief sand and gravel coastline. The seabed near the harbor is a largely featureless expanse of sand and gravel that deepens gradually, only reaching a depth of -40 feet (-12.2 m) mean lower low water (MLLW) at a distance of 3,000 feet (914.4 m) offshore.

The movement of littoral drift depends on the wave climate and the incident wave angle to the beach. Waves primarily approach the harbor site from the southwest, so net sediment at Nome is from west to east. This is evidenced by the large accumulation of sediment on the west side of the harbor causeway, which tends to serve as a littoral barrier. The gross annual sediment transport rate is estimated at 180,500 cubic yards (138,002 m3), while the net transport towards the east is an estimated 60,170 cubic yards (46,003 m3) each year. Sampling and chemical analysis of harbor sediments at Nome has shown little indication of significant human-caused chemical contamination. However, notably high concentrations (up to 200 mg/kg) of arsenic have been reported regularly in sediment samples from the harbor area (Figure 1). The National Oceanic and Atmospheric Administration (NOAA) has published marine sediment threshold effects levels (TELs) for arsenic as low as 7 mg/kg (Buchman 2008). Previous concern over high concentrations of arsenic in the Nome harbor dredged material led to the burial of material within the harbor basin under a 3.3 ft (1 meter) thick cap in 1995 and 1996 (USACE 2012).

Figure 1. Arsenic concentrations in Nome sediment samples (Photo: USACE)

The elevated concentrations of arsenic in some Seward Peninsula mineral formations and in the sediments of regional streams (including the Snake River) are well established (USKH 2012). Arsenic sulfide compounds are commonly associated with gold (Straskraba and Moran 2006), and the Nome area has been the scene of intense for more than a century. The presence of natural sources of arsenic and the lack of identifiable human-generated sources of arsenic at Nome Harbor suggest that the high concentrations of arsenic detected in some samples of the harbor sediment are due primarily to local mineralogy. Soil samples from borings along Nome Spit in 2000 also showed consistently high levels of arsenic (up to 93 mg/kg) even at depths of greater than 20 feet (6.1 m) below the surface (USACE 2001), suggesting that the marine sediments that formed the spit were also rich in arsenic. The waters of Norton Sound are characteristically turbid due to an enormous load of sediment discharged by the Yukon River to the south and carried throughout the Sound by a counterclockwise gyre (Cacchione and Drake 1979). These sediments, once deposited on the sea floor, can be readily resuspended by severe storms, especially given the shallow depths throughout Norton Sound. Scouring and gouging of the sea bottom sediments by sea ice is believed to occur at depths as great as 40 feet below the surface in Norton Sound. Ice scouring, along with massive movements of sediment caused by storms, presumably plays a major role in the composition, , and abundance of benthic organisms (USACE 2012).

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Dredge Mining Suction dredging is a popular gold recovery method from placer gravels in freshwater streams and especially in marine sediments. Suction dredges are categorized by the size of the intake hose (nozzle) and horsepower of the pump engine. Various sizes of suction dredges are used, varying from “recreational” models with a small 1½ inch intake hose to large, heavy dredges with 8 inch and 10 inch intake hoses, driven by powerful engines, and capable of processing large amounts of material in a single day (ADF&G 2014).

There is no winter (under-ice) dredging allowed in the East and West Recreation areas. Winter dredging is only allowed on and mining claims. Suction dredges are only allowed in the two offshore recreational mining areas when occupied by the miner. Miners may not leave their suction dredge anchored in the recreational areas and go ashore. Floating suction dredge or a stationary high banker operated below the mean high tide is the only equipment allowed in the recreational mining areas. Tracked, wheeled and mechanical equipment are not allowed.

As noted, dredge mining activity can lead to the direct loss of EFH for certain species. Offshore mining, such as the extraction of gravel and gold in Norton Sound and the mining of gravel from beaches, can increase turbidity of water. Thus, the resuspension of organic materials could affect less motile organisms (i.e., eggs and recently hatched larvae) in the area. Benthic habitats could be damaged or destroyed by these actions. Mining large quantities of beach gravel may significantly affect the removal, transport, and deposition of sand and gravel along the shore, both at the mining site and down-current. These actions can damage or destroy benthic habitats. Changes in bathymetry and bottom type may also alter population and migrations patterns (Hurme and Pullen 1988). Neither the future extent of this activity nor the effects of such mortality on the abundance of marine species is known.

Maintenance dredging Nome Harbor consists of an approximately 3,950-foot (1204 m) long entrance , an inner harbor basin, and a sediment trap (Figure 2). These are dredged to project depths ranging from -22 feet (6.7 m) to -10 feet (3.0 m) MLLW. Annual maintenance dredging is regularly conducted within the Federal project limits at Nome Harbor to include the entrance channel, the inner north harbor, and the sediment traps as needed. Coastal transport mechanisms and storms deposit large quantities of marine sediment within the channel, and the Federal project must be dredged annually to maintain the authorized project depths and safe navigation. Without the proposed action, shoaling will rapidly restrict and access to Nome Harbor. The estimated quantity of sediment dredged for maintenance is about 50,000 cubic yards (38,228 m3) (USACE 2012).

Figure 2. Location of vicinity of Nome Harbor annual maintenance dredging in 2017. (Photo: USACE)

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Hopper Dredge A hopper dredge operates by use of suction “drag heads” that extend from the hull of the dredge down into the substrate to be dredged. Through suction, materials are brought up into the open hull of the dredge until the hopper is full and the material can then move to a dredged material placement site. Use of a hopper dredge works best in sandy environments. The suction of material also brings in huge volumes of water. The excess water (return water) is allowed to overflow the hopper and flow back into the waterbody. The overflow water can increase turbidity and may not meet water quality standards immediately after discharge (dewatering).

Pipeline Dredge A pipeline dredge, like the hopper dredge, uses suction and a cutter head to bring sediment from the bottom of the harbor. However, a pipeline dredge does not have a hopper to contain the material. Instead, the material is moved directly to the placement site. As with a hopper dredge, excess water is removed with the sediment. The excess water helps to keep the sediment “fluid” so that it can be pumped to the dredged material disposal facility. The pipeline dredge must have a placement location within pumping range of the dredge.

Clamshell Bucket Dredge The clamshell (or grab) bucket dredge, also commonly called a bucket dredge, is one of the commonly used dredges used in USACE navigation projects. The bucket dredge is so named because it uses a bucket to excavate material to be dredged (Figure 3.) Different types of buckets can fulfill various types of dredging requirements. The bucket dredging process usually requires that excavated material be hauled to a placement site by barge or scow (USACE 2015).

Site-Specific Preference Both clamshell and hydraulic pipeline dredges have been used at Nome in the past. The pipeline dredge has some distinct advantages for the maintenance dredging project at Nome. Pipeline dredges are able to operate almost continuously (without pauses to change out scows or hoppers), resulting in higher productivity and faster project completion. This efficiency helps as a mitigation measure for EFH in that it is easier to fit all required around seasonal work exclusion windows. At Nome, a pipeline discharge system allows the dredge and support craft to work almost entirely within the protection of the breakwater and causeway; if the dredged material had to be transported out of the harbor in a scow, high winds or unfavorable sea conditions could slow or temporarily halt the dredging operations (USACE 2012).

Dredged Material Placement The maintenance project now has only one viable placement site for the dredged material. The onshore placement area is at the shoreline at the western end of the rock seawall (Figure 2). This roughly 600-foot (183 m) by 300-foot (91 m) (less than 5 acres or 2.02 hectares) area primarily receives sediment dredged from the harbor basin and inner channel.

This placement site has been used successfully since 2009, and its use has contributed to the widening of the beach in front of the Nome seawall. The dredged material is placed at the waterline within this area and periodically spread with a grader or to match the surrounding beach profile. The dredged material discharged in this area serves as ; waves and current naturally redistribute it eastward along the foot of the seawall (USACE 2012).

ENVIRONMENTAL CONCERNS The natural environment includes the continuous migration and redistribution of benthic sediments, as well as frequent disruption from ice scouring and violent storms. Studies of the general biological setting offshore of Nome describe species typical of a high-energy, sandy and gravelly coastal environment dominated by epifaunal and infaunal species such as sea stars, polychaetes, bivalves, and amphipods that are adapted to a loose, shifting substrate (USACE 1998; Feder and Mueller 1974). The area is designated as EFH for all five species of Pacific salmon and Norton Sound red king crab (P. camtschaticus). NMFS has conducted several EFH consultations to mitigate impacts on Pacific salmon and Norton Sound red king crab (NSRKC) stocks since 1996.

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Pacific Salmon EFH Residents of Norton Sound have relied on fish for cultural and nutritional uses for thousands of years. Fishing occurs in both marine and fresh waters. Comprehensive harvest surveys estimate that the five species of Pacific salmon comprise about two thirds of the total fish harvest in the area, with king crab and other species making up the other third. For the mainland communities, diet surveys indicate that subsistence-caught fish contribute more than half of the meat, fish, and poultry consumed by area residents (Ballew et al. 2004; Magdanz et al. 1995). A comprehensive subsistence survey estimated that 5,130 residents of 12 area communities (not including Nome) harvested 471,068 pounds (213,673 kg) of salmon and 285,056 pounds (129,299 kg) of other fish for subsistence uses in 2006. (Ahmasuk et al. 2007) Two-thirds of the respondents reported consuming wild foods at least 3 days a week, and 20% consumed wild foods 6 or 7 days a week.

Several salmon harvest surveys in Norton Sound have produced similar subsistence harvest estimates. Conger and Magdanz conducted comprehensive surveys in Golovin and Brevig Mission in 1989, and estimated the harvest of all types of wild foods to be 605 edible pounds per person per year in Golovin and 579 edible pounds per person per year in Brevig Mission. These were similar to estimates of total wild food harvests in other small northwest Alaska communities. Salmon contributed 161 pounds (73 kg) per person in Golovin and 118 pounds (53.5 kg) per person in Brevig Mission.

In most areas of the state, adult salmon spawning begins in mid-July and extends through the fall. The eggs deposited in the stream bed do not emerge as free swimming fish until April or May of the following year. Salmon eggs deposited in stream bed gravels are extremely vulnerable to any type of disturbance such as suction dredges. Accordingly, the instream use of any suction dredge is generally prohibited in salmon spawning and rearing areas except for a period between May 15th and July 15th, when salmon eggs and salmon fry are least vulnerable to disturbance. These dates may vary depending upon the species of fish and the distances they must travel to reach their natural streams.

Crab EFH Common benthic invertebrates in Norton Sound include various echinoderms (sea stars and sea urchins), soft , and shrimp. The only commercially important benthic invertebrate is the red king crab (P. camtschaticus). NSRKC are a distinct biological and geographic group. The NSRKC population in Norton Sound is unique in that it:

1) is separate from other stocks in the Bering Sea (Seeb et al. 1989, Jewett 1999);

2) lives under the ice for 5 to 6 months a year (Dupre 1980); and,

3) is generally confined to waters less than 100 feet (30 meters) in depth.

Despite the importance of this stock, the life history details are largely unknown. However, NSRKC reproductive activities take place in March through June in nearshore waters. At that time, sexually mature female crab migrate into shallow waters (< 164 ft or < 50m) upstream from prevailing currents. There they release planktonic larvae which drift passively for 2-5 months before settling into benthic habitats. Young of the year (i.e., age 0 through 1 year) crab select cobble habitats (e.g., rocky rubble habitat) and avoid homogeneous mud or silt bottom. Early settling (i.e., before August) crabs are small and have a carapace width around 2 mm. Juveniles less than two years old live in shallow waters such as shell hash, cobble, algae and bryozoans to avoid . Survival of juvenile crab is primarily dependent on the availability and quality of cover from predators, and this has profound effects on juvenile population dynamics and recruitment. Older juveniles form pods and travel together, feeding at night. Pods consisting of tens of thousands of individuals are potentially vulnerable to dredging activities. Adult crabs migrate offshore during ice breakup beginning in May (Jewett et al 2013). These mature red king crabs move into deeper water (typically less than 650 feet (200 m) to feed. Females return to shallow waters to hatch their eggs as the cycle continues.

The NSRKC commercial fishery is currently the largest single species fishery in Norton Sound. NSRKC is one of the northernmost red king crab populations that can support a commercial fishery. It is distributed throughout Norton Sound with a westward limit of 167-168° W longitude in depths less than 98.4 ft (30

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meters). The summer commercial fishery started in 1977, and catch peaked in the late 1970s with retained annual catch of over 2.9 million pounds (1.32 million kg). Since 1982, retained catches have been below 0.5 million pounds (0.23 million kg), averaging 0.275 million pounds (0.12 million kg), including several low years in the 1990s. Retained catches have increased to about 0.4 million pounds (0.18 million kg) in recent years coincident with increases in estimated abundance.

The fishery not only supports commercial crabbers, but also the many Norton Sound residents who partake in subsistence fishing. Red king crab frequent the offshore waters off the Seward Peninsula during winter and are harvested by subsistence fishermen through the ice.

MITIGATION Mine Dredging In Norton Sound, studies demonstrate that seafloor mining decreases habitat complexity and diversity. Recovery is slow particularly for waters deeper than 30 feet (9.1 m). Subsequent information and further investigations supported this depth because naturally occurring impacts (i.e., storm surges, ice gouging) occur in depths greater than 20 feet (6.1 m) and create a very dynamic environment (Jewett, S.C. 1999). Thus in working with the USACE and EPA, NMFS’ conservation recommendation was to limit mining activities to water depths of less than 30 feet (9.1 m).

As a general rule, all mining is prohibited year-round within the 0.5 mile (0.8 km) distance (radius) from any anadromous river mouth. Additionally, for 10 inch (25.4 cm) and larger suction dredge or mechanical placer mining operations, such as an on a barge, mining within the 1 mile distance (radius) of any anadromous river mouth between the annual dates of June 1 – July 15 is prohibited. Exceptions to these mining prohibitions are as follows: Mining offshore at a distance of 500 feet (152.4 m) from the mouths of local anadromous rivers is allowed between September 15 and December 1. At no time may any mining operation be closer than 500 feet (152.4 m) to these three river mouths.

Maintenance Dredging Maintenance dredging is required to start as soon as the ice goes out, but must be completed in the narrow inner channel area by 25 June, and in the rest of the project area by 31 July. This work window is intended to protect juvenile salmon, which are believed to start out-migration from Snake River in mid-June. Moreover this timing window was recommended to prevent entrainment of NSRKC juveniles that settle out of the water column onto the benthos in August and the disturbance of the benthos during this vulnerable life stage.

Modifications to the harbor have been made to enhance EFH. The previous harbor entrance channel was filled in, a new channel was breached through the Snake River sand spit, and a protected outer approach channel was formed by a new breakwater to the east of and roughly parallel to the existing causeway. The causeway and the new breakwater are both breached near shore to facilitate the passage/migration of marine organisms (e.g., crab, salmon), small watercraft, and some sediment.

CONCLUSION NOAA recommends that stakeholders initiate correspondence early in the planning stages of a dredge project to effectively minimize adverse effects on EFH. Communication with NOAA prior to the development of a formal EFH Assessment can help stakeholders incorporate the most relevant science and effective mitigation measures into their assessment. Such forethought and careful planning can help to meet the goals of the dredging operation and meet NOAA’s mission to manage, conserve, and protect living marine resources in inland, coastal, and offshore waters of the .

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