Natural Resources Consultants Inc.

Seattle, WA, United States

Natural Resources Consultants Inc.

Seattle, WA, United States

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Good T.P.,National Oceanic and Atmospheric Administration | June J.A.,Natural Resources Consultants Inc. | Etnier M.A.,Applied Osteology | Broadhurst G.,Northwest Straits Commission
Marine Pollution Bulletin | Year: 2010

Derelict fishing gear remains in the marine environment for years, entangling, and killing marine organisms worldwide. Since 2002, hundreds of derelict nets containing over 32,000 marine animals have been recovered from Washington's inland waters. Analysis of 870 gillnets found many were derelict for years; most were recovered from northern Puget Sound and high-relief rocky habitats and were relatively small, of recent construction, in good condition, stretched open, and in relatively shallow water. Marine organisms documented in recovered gillnets included 31,278 invertebrates (76 species), 1036 fishes (22 species), 514 birds (16 species), and 23 mammals (4 species); 56% of invertebrates, 93% of fish, and 100% of birds and mammals were dead when recovered. For all taxa, mortality was generally associated with gillnet effectiveness (total area, age and condition, and suspension in the water). Mortality from derelict fishing gear is underestimated at recovery and may be important for species of economic and conservation concern.


Ruggerone G.T.,Natural Resources Consultants Inc. | Agler B.A.,Alaska Department of Fish and Game | Nielsen J.L.,Evergreen State College
Environmental Biology of Fishes | Year: 2012

Increasing production of hatchery salmon over the past four decades has led to concerns about possible density-dependent effects on wild Pacific salmon populations in the North Pacific Ocean. The concern arises because salmon from distant regions overlap in the ocean, and wild salmon populations having low productivity may compete for food with abundant hatchery populations. We tested the hypothesis that adult length-at-age, age-at-maturation, productivity, and abundance of a Norton Sound, Alaska, chum salmon population were influenced by Asian hatchery chum salmon, which have become exceptionally abundant and surpassed the abundance of wild chum salmon in the North Pacific beginning in the early 1980s. We found that smaller adult length-at-age, delayed age-at-maturation, and reduced productivity and abundance of the Norton Sound salmon population were associated with greater production of Asian hatchery chum salmon since 1965. Modeling of the density-dependent relationship, while controlling for other influential variables, indicated that an increase in adult hatchery chum salmon abundance from 10 million to 80 million adult fish led to a 72% reduction in the abundance of the wild chum salmon population. These findings indicate that competition with hatchery chum salmon contributed to the low productivity and abundance of Norton Sound chum salmon, which includes several stocks that are classified as Stocks of Concern by the State of Alaska. This study provides new evidence indicating that large-scale hatchery production may influence body size, age-at-maturation, productivity and abundance of a distant wild salmon population. © Springer Science+Business Media B.V. 2011.


Cordell J.R.,University of Washington | Toft J.D.,University of Washington | Gray A.,Cramer Fish science | Ruggerone G.T.,Natural Resources Consultants Inc. | Cooksey M.,University of Washington
Ecological Engineering | Year: 2011

The Duwamish estuary is an industrialized waterway located in Seattle, WA, USA. Despite a history of habitat loss, naturally produced juvenile Chinook salmon use the estuary. In addition to experiencing degraded habitat in the estuary, wild salmon growth may be affected by competition with more than three million hatchery fish released yearly into the river. Restoring habitat to benefit salmon in the Duwamish River is a priority for trustees of public resources, and a number of wetland restoration sites have been created there. We tested the function of restored sites in the Duwamish estuary for juvenile Chinook salmon by comparing fish densities from enclosure nets or beach seines at three paired restored/un-restored sites and by applying environmental and diet data to a bioenergetics model. We also examined temporal and diet overlap of wild juvenile Chinook salmon with other salmon species and with hatchery-reared Chinook salmon using non-metric multidimensional scaling (NMDS). At a brackish upstream site with a relatively large opening to the river, we found higher densities of juvenile Chinook salmon at the restored site. NMDS results indicated that juvenile Chinook salmon fed on different taxa at the restored sites than at the reference sites. However, modeled growth was similar at restored and reference sites. Co-occurring juvenile chum and Chinook salmon fed differently, with chum eating smaller prey, and Chinook salmon eating larger prey. Co-occurring hatchery and wild juvenile Chinook salmon had similar diets, indicating that they may compete for prey. However, modeled growth was positive and did not differ between hatchery and wild fish, suggesting that food was not limiting. Bioenergetics models indicated that overall juvenile Chinook salmon growth potential at the brackish water site was consistently higher than at more saline sites. Our results suggest that restoration sites in the Duwamish estuary that have larger access openings and are located in brackish water may have increased function over other configurations. © 2010 Elsevier B.V.


Agler B.A.,Alaska Department of Fish and Game | Ruggerone G.T.,Natural Resources Consultants Inc. | Wilson L.I.,Alaska Department of Fish and Game | Mueter F.J.,University of Alaska
Deep-Sea Research Part II: Topical Studies in Oceanography | Year: 2013

We examined Bristol Bay and Yukon River adult chum salmon scales to determine whether climate variability, such as changes in sea surface temperature and climate indices, and high pink and Asian chum salmon abundance reduced chum salmon growth. Annual marine growth increments for 1965-2006 were estimated from scale growth measurements and were modeled as a function of potential explanatory variables using a generalized least squares regression approach. First-year growth of salmon originating from Bristol Bay and the Yukon River showed increased growth in association with higher regional ocean temperatures and was negatively affected by wind mixing and ice cover. Third-year growth was lower when Asian chum salmon were more abundant. Contrary to our hypothesis, warmer large-scale sea surface temperatures in the Gulf of Alaska were also associated with reduced third-year growth. Negative effects of high abundances of Russian pink salmon on third-year growth provided some evidence for interspecific interactions, but the effects were smaller than the effects of Asian chum salmon abundance and Gulf of Alaska sea surface temperature. Although the relative effects of Asian chum salmon and sea surface temperature on the growth of Yukon and Bristol Bay chum salmon were difficult to untangle, we found consistent evidence that high abundances of Asian chum salmon contributed to a reduction in the growth of western Alaska chum salmon. © 2013 Elsevier Ltd.


Nielsen J.L.,South Sound Marine Institute | Ruggerone G.T.,Natural Resources Consultants Inc. | Zimmerman C.E.,U.S. Geological Survey
Environmental Biology of Fishes | Year: 2013

In the warming Arctic, aquatic habitats are in flux and salmon are exploring their options. Adult Pacific salmon, including sockeye (Oncorhynchus nerka), coho (O. kisutch), Chinook (O. tshawytscha), pink (O. gorbuscha) and chum (O. keta) have been captured throughout the Arctic. Pink and chum salmon are the most common species found in the Arctic today. These species are less dependent on freshwater habitats as juveniles and grow quickly in marine habitats. Putative spawning populations are rare in the North American Arctic and limited to pink salmon in drainages north of Point Hope, Alaska, chum salmon spawning rivers draining to the northwestern Beaufort Sea, and small populations of chum and pink salmon in Canada's Mackenzie River. Pacific salmon have colonized several large river basins draining to the Kara, Laptev and East Siberian seas in the Russian Arctic. These populations probably developed from hatchery supplementation efforts in the 1960's. Hundreds of populations of Arctic Atlantic salmon (Salmo salar) are found in Russia, Norway and Finland. Atlantic salmon have extended their range eastward as far as the Kara Sea in central Russian. A small native population of Atlantic salmon is found in Canada's Ungava Bay. The northern tip of Quebec seems to be an Atlantic salmon migration barrier for other North American stocks. Compatibility between life history requirements and ecological conditions are prerequisite for salmon colonizing Arctic habitats. Broad-scale predictive models of climate change in the Arctic give little information about feedback processes contributing to local conditions, especially in freshwater systems. This paper reviews the recent history of salmon in the Arctic and explores various patterns of climate change that may influence range expansions and future sustainability of salmon in Arctic habitats. A summary of the research needs that will allow informed expectation of further Arctic colonization by salmon is given. © 2012 Springer Science+Business Media B.V.


Griffiths J.R.,University of Washington | Schindler D.E.,University of Washington | Balistrieri L.S.,U.S. Geological Survey | Ruggerone G.T.,Natural Resources Consultants Inc.
Limnology and Oceanography | Year: 2011

We used a hydrodynamics model to assess the consequences of climate warming and contemporary geomorphic evolution for thermal conditions in a large, shallow Alaskan lake. We evaluated the effects of both known climate and landscape change, including rapid outlet erosion and migration of the principal inlet stream, over the past 50 yr as well as future scenarios of geomorphic restoration. Compared to effects of air temperature during the past 50 yr, lake thermal properties showed little sensitivity to substantial (, 60%) loss of lake volume, as the lake maximum depth declined from 6 m to 4 m driven by outlet erosion. The direction and magnitude of future lake thermal responses will be driven largely by the extent of inlet stream migration when it occurs simultaneously with outlet erosion. Maintaining connectivity with inlet streams had substantial effects on buffering lake thermal responses to warming climate. Failing to account for changing rates and types of geomorphic processes under continuing climate change may misidentify the primary drivers of lake thermal responses and reduce our ability to understand the consequences for aquatic organisms. © 2011, by the American Society of Limnology and Oceanography, Inc.


Ruggerone G.T.,Natural Resources Consultants Inc. | Peterman R.M.,Simon Fraser University | Dorner B.,Simon Fraser University | Myers K.W.,University of Washington
Marine and Coastal Fisheries | Year: 2010

Abundance estimates of wild and hatchery Pacific salmon Oncorhynchus spp. are important for evaluation of stock status and density-dependent interactions at sea. We assembled available salmon catch and spawning abundance data for both Asia and North America and reconstructed total abundances of pink salmon O. gorbuscha, chum salmon O. keta, and sockeye salmon O. nerka during 1952-2005 Abundance trends were evaluated with respect to species, regional stock groups, and climatic regimes. Wild adult pink salmon were the most numerous salmon species (average=268×106 fish/year, or 70% of the total abundance of the three species), followed by sockeye salmon (63×106 fish/year, or 17%) and chum salmon (48×106 fish/year, or 13%). After the 1976-1977 ocean regime shift, abundances of wild pink salmon and sockeye salmon increased by more than 65% on average, whereas abundance of wild chum salmon was lower in recent decades. Although wild salmon abundances in most regions of North America increased in the late 1970s, abundances in Asia typically did not increase until the 1990s. Annual releases of juvenile salmon from hatcheries increased rapidly during the 1970s and 1980s and reached approximately 4.5×109 juveniles/year during the 1990s and early 2000s. During 1990-2005, annual production of hatchery-origin adult salmon averaged 78×106 chum salmon, 54×106 pink salmon, and 3.2×106 sockeye salmon, or approximately 62, 13, and 4%, respectively, of the combined total wild and hatchery salmon abundance. The combined abundance of adult wild and hatchery salmon during 1990-2005 averaged 634×106 salmon/year (498×106 wild salmon/year), or approximately twice as many as during 1952-1975 The large and increasing abundances of hatchery salmon have important management implications in terms of density-dependent processes and conservation of wild salmon populations; management agencies should improve estimates of hatchery salmon abundance in harvests and on the spawning grounds. © American Fisheries Society 2010.


Cunningham C.J.,University of Washington | Ruggerone G.T.,Natural Resources Consultants Inc. | Quinn T.P.,University of Washington
American Naturalist | Year: 2013

Can variation in prey density drive changes in the intensity or direction of selective predation in natural systems? Despite ample evidence of density-dependent selection, the influence of prey density on predatory selection patterns has seldom been investigated empirically. We used 20 years of field data on brown bears (Ursus arctos) foraging on sockeye salmon (Oncorhynchus nerka) in Alaska, to test the hypothesis that salmon density affects the strength of size-selective predation. Measurements from 41,240 individual salmon were used to calculate variance-standardized selection differentials describing the direction and magnitude of selection. Across the time series, the intensity of predatory selection was inversely correlated with salmon density; greater selection for smaller salmon occurred at low salmon densities as bears' tendency to kill larger-than-average salmon was magnified. This novel connection between density dependence and selective predation runs contrary to some aspects of optimal foraging theory and differs from many observations of density-dependent selection because (1) the direction of selection remains constant while its magnitude changes as a function of density and (2) stronger selection is observed at low abundance. These findings indicate that sockeye salmon may be subject to fishery-induced size selection from both direct mechanisms and latent effects of altered predatory selection patterns on the spawning grounds, resulting from reduced salmon abundance. © 2013 by The University of Chicago All rights reserved.


Westley P.A.H.,University of Washington | Westley P.A.H.,Memorial University of Newfoundland | Schindler D.E.,University of Washington | Quinn T.P.,University of Washington | And 2 more authors.
Oecologia | Year: 2010

The metacommunity concept has recently been described to account for the roles of dispersal in regulating community structure. Despite its strong theoretical basis, there exist few large-scale and long-term examples of its applicability in aquatic ecosystems. In this study we used a long-term dataset (1961-2007) on the relative abundances of the dominant limnetic fishes from two interconnected lakes to investigate the synergistic effects of naturally declining lake volume (approximately 50% in 50 years), climate variation, fishery management, and dispersal on community composition. We found a marked shift in fish community composition and variability during a period of rapid natural habitat change; however, the change was most apparent in the downstream, more stable lake of the system rather than at the site of disturbance. Multivariate analysis suggested significant shifts in community composition and variability in the downstream lake. Results indicated that the community composition in both lakes was best explained by habitat loss in the upper watershed and the number of spawning adult sockeye salmon the previous year (reflecting both natural processes and commercial fishing). Furthermore, communities exhibited site-specific responses to climatic conditions (e.g., index of the Pacific Decadal Oscillation), whereby the upper lake responded to climate within a given year and with a 1-year time lag, whereas the downstream community responded only with a 1-year lag. We attribute this difference largely to downstream dispersal and recruitment of fish from the upper lake. Thus, we suggest that the interconnected nature of the communities in this system provides a useful and large-scale example of the metacommunity concept, whereby the effects of environmental disturbance on community structure ultimately depend on the effects of these disturbances on dispersal among ecosystems. © 2009 Springer-Verlag.


Connors B.M.,Simon Fraser University | Braun D.C.,Simon Fraser University | Peterman R.M.,Simon Fraser University | Cooper A.B.,Simon Fraser University | And 5 more authors.
Conservation Letters | Year: 2012

Climate, competition, and disease are well-recognized drivers of population dynamics. These stressors can be intertwined by animal migrations, leading to uncertainty about the roles of natural and anthropogenic factors in conservation and resource management. We quantitatively assessed the four leading hypotheses for an enigmatic long-term decline in productivity of Canada's iconic Fraser River sockeye salmon: (1) delayed density-dependence, (2) local oceanographic conditions, (3) pathogen transmission from farmed salmon, and (4) ocean-basin scale competition with pink salmon. Our findings suggest that the long-term decline is primarily explained by competition with pink salmon, which can be amplified by exposure to farmed salmon early in sockeye marine life, and by a compensatory interaction between coastal ocean temperature and farmed-salmon exposure. These correlative relationships suggest oceanic-scale processes, which are beyond the reach of current regulatory agencies, may exacerbate local ecological processes that challenge the coexistence of fisheries and aquaculture-based economies in coastal seas. © 2012 Wiley Periodicals, Inc.

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