Puget Sound holds a surprisingly rich community of fish, from schooling forage species near the surface to deep-dwelling sharks hundreds of feet below. Surface trawl surveys across the Sound’s multiple basins typically turn up Pacific herring, surf smelt, Pacific sand lance, threespine stickleback, and several species of juvenile salmon as the most frequently encountered fish, though total species richness per sampling site tends to be modest, often fewer than ten species per tow.1Marine and Coastal Fisheries. Geographic Patterns of Fishes and Jellyfish in Puget Sound Surface Waters Beneath that surface layer, the picture expands to include rockfish, flatfish, Pacific hake, walleye pollock, and even bluntnose sixgill sharks cruising the deep channels. The mix of species varies basin by basin and season by season, shaped by habitat, water depth, and an increasingly complicated set of human pressures.
The Forage Fish That Drive the Food Web
If you want to understand Puget Sound’s fish community, start with the small species that everything else depends on. Pacific herring, surf smelt, and Pacific sand lance are the three pillars of the forage fish base. Herring form dense schools in the upper water column and are particularly abundant in Rosario Basin, Whidbey Basin, and the Main Basin, though less so in South Sound.2Marine and Coastal Fisheries. Geographic Patterns of Fishes and Jellyfish in Puget Sound Surface Waters Surf smelt and sand lance tend to be associated with sandy or gravelly beaches where they spawn, depositing eggs in the intertidal zone. These small fish channel energy from plankton upward to salmon, seabirds, and marine mammals.
Forage fish abundance is tightly linked to shoreline condition. Herring, shiner perch, and surf smelt are all found in much higher numbers over eelgrass beds than over bare sand or mud. In the Skagit River delta, herring and shiner perch densities in eelgrass were several times higher than in unvegetated areas, and juvenile Chinook salmon were also more abundant in eelgrass during early summer.3Marine and Coastal Fisheries. Juvenile Chinook Salmon and Forage Fish Use of Eelgrass Habitats in a Diked and Channelized Puget Sound River Delta Where eelgrass beds have been lost to shoreline development, both forage fish and juvenile salmon lose critical rearing and feeding habitat.
Salmon Species and How They Use the Sound
Puget Sound is home to all five Pacific salmon species: Chinook, coho, chum, pink, and sockeye. Their use of the Sound’s waters varies depending on life stage and geography. Juvenile Chinook salmon show extended nearshore residence in northern Puget Sound, where they grow significantly before moving offshore, while juvenile chum tend to concentrate in southern areas.4Estuarine, Coastal and Shelf Science. Early marine life history of juvenile Pacific salmon in two regions of Puget Sound Surface surveys confirm this pattern: South Sound catches contain higher proportions of chum salmon and hatchery-marked Chinook compared to northern basins.5Marine and Coastal Fisheries. Geographic Patterns of Fishes and Jellyfish in Puget Sound Surface Waters
Chinook salmon get the most attention because many Puget Sound runs are listed under the Endangered Species Act, and because they are a primary prey item for the region’s endangered Southern Resident killer whales. But chum and pink salmon often constitute the numerical bulk of the salmon passing through the Sound in a given year, and coho are ecologically important in their own right, especially in smaller tributaries.
Estuary restoration projects have demonstrated a clear benefit for juvenile salmon. When formerly diked or developed shorelines are returned to tidal function, invertebrate prey production increases, and juvenile Chinook, chum, and coho all appear to gain foraging opportunities.6Restoration Ecology. Enhanced invertebrate prey production following estuarine restoration supports foraging for multiple species of juvenile salmonids (Oncorhynchus spp.) These restored areas act as nursery habitat during the vulnerable early marine phase when young salmon first leave freshwater.
Rockfish, Flatfish, and Other Demersal Species
Below the surface schools of herring and salmon, Puget Sound’s deeper waters support a different cast. Pacific hake, walleye pollock, English sole, and several rockfish species occupy the middle and bottom of the water column. Researchers have tracked the trophic positions of five of these species over the past century and found that most have been feeding at roughly the same level in the food web for that entire span. The one exception is copper rockfish, whose trophic position has increased over time, meaning it appears to be eating higher on the food chain now than it did decades ago.7Marine Ecology Progress Series. Reconstructing trophic position over the past century for five Puget Sound fish species
Rockfish as a group have been a conservation concern in the Sound for years. Many species are long-lived, slow to reproduce, and tied to rocky reef habitat that is limited in extent. Puget Sound rockfish, a small species found in northern parts of the Sound, has shown measurable changes in growth and recruitment patterns, suggesting population-level stress.8Biology, Assessment, and Management of North Pacific Rockfishes. Changes in growth and recruitment of the Puget Sound rockfish (Sebastes emphaeus) in northern Puget Sound Because rockfish can live for decades and do not bounce back quickly from depletion, even modest overfishing or habitat degradation can have long-lasting effects.
English sole and other flatfish are useful indicators of bottom-habitat health. Studies from contaminated urban embayments found that subadult flatfish, including English sole, rock sole, and starry flounder, developed liver lesions at significantly higher rates at polluted sites. The prevalence of these pre-cancerous and degenerative lesions tracked closely with concentrations of chemical contaminants in the fish’s bile and liver tissue.9Marine Environmental Research. Hepatic lesions other than neoplasms in subadult flatfish from Puget Sound, Washington: relationships with indices of contaminant exposure Flatfish essentially serve as living pollution monitors because they sit on contaminated sediments and accumulate toxicants through their diet.
Sixgill Sharks in Deep Puget Sound
One of the more unexpected residents is the bluntnose sixgill shark, a large deep-water predator that uses Puget Sound’s deep basins year-round. Acoustic tracking of 27 sixgill sharks over two years revealed that they follow a clear daily rhythm: they move into shallower water at night and retreat to depth during the day. This pattern held across shark sizes and sexes throughout the year, and researchers concluded it was driven primarily by foraging behavior rather than temperature preference or predator avoidance.10Animal Behaviour. Diel activity patterns of sixgill sharks, Hexanchus griseus: the ups and downs of an apex predator
On a broader scale, sixgill sharks also make seasonal shifts in location within Puget Sound. When researchers tried to explain these larger movements using the day-to-day tracking data, they found the daily movement model could not account for what the passive monitoring receivers were detecting. The sharks periodically made large, fast, directed movements that did not show up during short-duration active tracking. Adding these burst-movement behaviors to the model allowed researchers to reproduce the seasonal patterns observed over roughly 150 days of monitoring.11Current Zoology. An empirical movement model for sixgill sharks in Puget Sound: Combining observed and unobserved behavior In other words, these sharks live structured lives in Puget Sound, alternating between routine nightly foraging and occasional long-distance relocations.
Contaminants in the Water and in the Fish
Puget Sound is ringed by cities, industrial zones, and highways, and the chemical legacy of that development accumulates in its fish. Persistent organic pollutants like PCBs and PBDEs have been tracked in both bottom-dwelling and open-water species for decades, and residence time in Puget Sound is itself a risk factor: fish that spend more of their lives feeding within the Sound accumulate higher levels of these compounds than those passing through.12PubMed Central. Time Trends of Persistent Organic Pollutants in Benthic and Pelagic Indicator Fishes from Puget Sound, Washington, USA
Chinook salmon offer a striking example of how feeding habits shape contamination. Stocks that rear along the continental shelf near urban coastlines carry roughly 12-fold higher PCB concentrations and 46-fold higher PBDE concentrations than stocks that feed farther offshore. The nearshore-rearing fish also carry heavier, more bioaccumulative forms of these contaminants, driven by land-based industrial sources.13PubMed. Polychlorinated biphenyl and polybrominated diphenyl ether profiles vary with feeding ecology and marine rearing distribution among 10 Chinook salmon (Oncorhynchus tshawytscha) stocks in the North Pacific Ocean For Puget Sound’s Chinook, this is especially concerning because several populations are already endangered and because killer whales eat large numbers of them, passing those contaminants up the food chain once more.
A newer threat is 6PPD-quinone, a chemical created when a common tire rubber additive reacts with ozone. This compound washes into waterways with stormwater runoff and is acutely lethal to coho salmon. Research on developing coho embryos has shown that 6PPD-quinone disrupts the molecular pathways that maintain blood vessel integrity, particularly at the blood-brain barrier. Genes controlling the tight junctions between cells were thrown off in exposed fish, strongly implicating increased vascular permeability as a key mechanism of toxicity.14PubMed Central. Tire-Derived Transformation Product 6PPD-Quinone Induces Mortality and Transcriptionally Disrupts Vascular Permeability Pathways in Developing Coho Salmon Coho in urban Puget Sound streams have experienced mysterious pre-spawn die-offs for years, and this chemical appears to be a major culprit.
Microplastics in Puget Sound Fish
Plastics are another emerging contaminant. A study examining forage fish and salmon across the Salish Sea found microplastics in about three-quarters of all salmon stomachs and a quarter of Pacific sand lance stomachs. The plastic pieces were overwhelmingly fibers, the kind that shed from synthetic textiles during laundering. Chinook salmon stood out for ingesting relatively more films and hard particles in addition to fibers. There was also a slight negative relationship between the amount of plastic in a fish’s stomach and how full that stomach was, hinting that plastic might be retained rather than passing through quickly.15PubMed Central. Influence of marine habitat on microplastic prevalence in forage fish and salmon in the Salish Sea Sand lance collected from beach habitats had more microplastics than those sampled from subtidal sediments, which makes sense given that beaches concentrate debris at the tide line, right where sand lance spawn and feed.
Shoreline Armoring and Spawning Habitat
Much of Puget Sound’s shoreline has been hardened with bulkheads, riprap, and seawalls to protect waterfront property. The ecological cost of this armoring goes beyond the individual property line. When large portions of a sediment drift cell are armored, the natural supply of sand and gravel to downdrift beaches can be cut off. Over time, this shifts beach grain sizes, reducing the finer gravels and sands that forage fish like surf smelt and sand lance need for spawning.16Estuarine, Coastal and Shelf Science. Multiscale impacts of armoring on Salish Sea shorelines: Evidence for cumulative and threshold effects The effects are cumulative and may cross thresholds where the damage becomes difficult to reverse. A single bulkhead might not matter much; an entire neighborhood of them can starve a spawning beach of the sediment it needs.
Predation Pressure and the Hatchery Complication
Young salmon leaving Puget Sound rivers face a gauntlet of predators, including harbor seals, diving birds, and larger fish. Harbor seal populations in the broader Salish Sea region have recovered substantially since the Marine Mammal Protection Act of 1972, and their appetite for juvenile salmon is not trivial. In the adjacent Strait of Georgia, one study estimated that harbor seals consumed roughly half of all juvenile coho salmon annually between 2004 and 2016.17Marine and Coastal Fisheries. Quantifying impacts of harbor seal Phoca vitulina predation on juvenile Coho Salmon in the Strait of Georgia, British Columbia While that study focused on British Columbia waters, the same seal populations extend into Puget Sound, and similar dynamics are at work.
Hatcheries add another wrinkle. Millions of hatchery salmon are released into Puget Sound tributaries every year, and the timing and size of those releases matters. Research indicates that current hatchery practices often release Chinook salmon at the size range most preferred by fish, bird, and marine mammal predators, potentially increasing predation mortality for both hatchery and wild fish in the same waters.18Ecosphere. Ecological implications of changing hatchery practices for Chinook salmon in the Salish Sea Beyond predation, there is strong evidence that artificial propagation itself can reduce the fitness of salmon for natural spawning and rearing. When hatchery fish interbreed with wild fish, the genetic changes accumulated over even a few generations in the hatchery environment can lower the productivity of the combined population.19ICES Journal of Marine Science. Genetic changes from artificial propagation of Pacific salmon affect the productivity and viability of supplemented populations
Parasites and Disease in a Warming Sound
Fish in Puget Sound carry a wide range of pathogens, from nematodes and trematodes to bacteria, viruses, and parasitic crustaceans.20Fisheries. Infectious Diseases of Fishes in the Salish Sea Most of the time, these infections exist as a background cost of living in the marine environment. They become a bigger problem when fish are already stressed by poor water quality, contaminant exposure, or warm water temperatures.
Steelhead trout migrating out of Puget Sound rivers offer a case study. Fish from southern and central rivers carried higher loads of the parasite Nanophyetus salmincola and higher levels of persistent organic pollutants than steelhead from a northern river system. Those same southern and central populations showed lower early marine survival.21Journal of Aquatic Animal Health. Infection by Nanophyetus salmincola and Toxic Contaminant Exposure in Out‐migrating Steelhead from Puget Sound, Washington: Implications for Early Marine Survival The picture that emerges is one of multiple stressors stacking up: a fish carrying parasites while loaded with industrial chemicals and swimming through warming water faces worse odds than any one of those stressors alone would predict.
Boat Noise and Behavioral Disruption
Vessel traffic in Puget Sound is heavy, and the noise it generates reaches fish. Experiments with herring and juvenile salmon in open net pens showed that both groups changed their behavior in response to passing boats. Herring were more sensitive, with a 50% probability of reacting at received sound levels around 123 decibels, while juvenile pink and chum salmon required louder exposures, around 140 decibels, to show the same probability of response. Both species spent more time in behaviors consistent with predator avoidance during boat passes, and researchers noted that repeated triggering of these responses could increase energy costs or reduce feeding time.22PubMed. Behavioural responses of wild Pacific salmon and herring to boat noise For fish already dealing with contamination and habitat loss, this kind of chronic disturbance is another drain on an already tight energy budget.
Net-Pen Aquaculture and Non-Native Fish
Puget Sound has hosted marine net-pen aquaculture operations, historically including Atlantic salmon farms. A comprehensive risk assessment of Atlantic salmon interactions in the Pacific Northwest identified two primary concerns for the local ecosystem: the impact on bottom sediments from biological deposits beneath the net pens, and the accumulation of heavy metals, particularly zinc and copper, in those sediments. Both effects were found to be reversible within a year or two once a site was fallowed.23ScienceDirect. Interactions of Atlantic salmon in the Pacific Northwest: IV. Impacts on the local ecosystems Washington State has since moved to phase out Atlantic salmon net pens following a high-profile pen collapse in 2017 that released thousands of non-native fish into Puget Sound, though the ecological fallout from that event was limited.
Thousands of Years of Indigenous Fish Harvesting
The fish community of Puget Sound has been shaped by human hands far longer than modern development has existed. Archaeological evidence from Coast Salish sites shows that Indigenous peoples sustainably harvested chum salmon for nearly 3,000 years. The relative abundance of salmon species in the archaeological record remained remarkably consistent over that entire span, suggesting intentional stewardship rather than exploitation to depletion.24PubMed Central. Archaeology demonstrates sustainable ancestral Coast Salish salmon stewardship over thousands of years
Herring tell a similar story. Ancient DNA extracted from herring bones at Coast Salish archaeological sites revealed that ancestors harvested from a portfolio of different herring spawning populations across multiple centuries. By spreading their harvest across groups that spawned at different times and places, they benefited from a natural resource wave and avoided overexploiting any single population.25PubMed Central. Ancient DNA reveals phenological diversity of Coast Salish herring harvests over multiple centuries This kind of diversified harvesting is exactly what modern fisheries science now recommends for resilience, and it was already standard practice in the Salish Sea long before Europeans arrived. Today, tribal co-management remains central to salmon and herring policy in Puget Sound, with treaty tribes retaining legally affirmed fishing rights and playing active roles in habitat restoration and stock monitoring.