Abiotic and Biotic Dimensions of Habitat for Juvenile Salmon and Other Fishes in the Skeena River Estuary PDF Download
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Author: Ciara Sharpe Publisher: ISBN: Category : Languages : en Pages : 98
Book Description
Estuaries are increasingly degraded globally but provide nursery services for juvenile fishes through predator protection and increased food availability. This thesis examined the abiotic and biotic factors that contributed to abundance patterns of juvenile salmon and forage fish species in the Skeena River estuary, BC. I first showed that spatial abundance patterns were heterogeneous for salmon and that the combination of variables that predicted abundance differed between species. Inclusion of these dynamic abiotic and biotic variables increased predictive power over solely using static habitat descriptors for juvenile salmon. Next, I examined the association between fish and prey abundance for two forage fish and juvenile salmon species. Overall, fish abundance was not related to prey abundance, except for herring which co-varied with a highly consumed prey species. Understanding the factors influencing estuarine habitat use by economically-important juvenile salmon and forage fish can help inform risk assessment and guide environmental planning.
Author: Ciara Sharpe Publisher: ISBN: Category : Languages : en Pages : 98
Book Description
Estuaries are increasingly degraded globally but provide nursery services for juvenile fishes through predator protection and increased food availability. This thesis examined the abiotic and biotic factors that contributed to abundance patterns of juvenile salmon and forage fish species in the Skeena River estuary, BC. I first showed that spatial abundance patterns were heterogeneous for salmon and that the combination of variables that predicted abundance differed between species. Inclusion of these dynamic abiotic and biotic variables increased predictive power over solely using static habitat descriptors for juvenile salmon. Next, I examined the association between fish and prey abundance for two forage fish and juvenile salmon species. Overall, fish abundance was not related to prey abundance, except for herring which co-varied with a highly consumed prey species. Understanding the factors influencing estuarine habitat use by economically-important juvenile salmon and forage fish can help inform risk assessment and guide environmental planning.
Author: Nichole K. Sather Publisher: ISBN: Category : Pacific salmon Languages : en Pages : 256
Book Description
The decline of many Pacific salmon stocks has stimulated interest in the early life history and habitat requirements of juvenile salmon. Although estuarine habitat associations of juvenile salmon have been investigated in many coastal areas of the eastern Pacific Ocean, until recently, little was known about juvenile salmonid ecology within the Straits of Juan de Fuca. During the Spring/Summer outmigration period in 2006 and 2007, I examined the early life history of the five species of anadromous salmon in the Dungeness River estuary on the north Olympic Peninsula, Washington. I sampled multiple spatial scales within several habitat types to characterize salmon distribution and habitat use. My results presented in this thesis are segregated into two components: 1) tidal marsh ecology of juvenile salmonids in the Dungeness River estuary, and 2) the landscape-scale distribution of juvenile salmonids within the Dungeness River estuary. I examined the population of juvenile salmonids within blind tidal sloughs near the vicinity of the Dungeness River delta. Salmonids were present within the tidal marshes throughout the entire outmigration period (e.g., March through July). Juvenile Chinook salmon (Oncorhynchus tshawytscha) were the most abundant salmonid species within the marshes. Based on the temporal distribution and size structure of juvenile Chinook salmon in the estuary I identified at least four life history types: 1) a fry strategy included a large pulse of fish emigrating from the river at a small size (e.g., 35-45mm FL) during late winter and early spring months; 2) the second group of fish was the least abundant group emigrating from the river from April through mid May at sizes ranging from 50-75mm FL; 3) the third group of migrants entered the estuary between from late spring through the summer months at larger sizes than the initial groups (e.g., 60-90mm FL); and 4) the final group of Chinook salmon included a stream-type yearling strategy. In addition to the four life history strategies identified for Chinook salmon, I detected at least three groups of chum salmon migrating into the estuary. These groups were distinguished by their size and timing of migration and are further described according to different rearing strategies. The distribution of juvenile salmonids was most strongly influenced by the degree of connectivity (i.e., distance) between the tidal marshes and the mouth of the Dungeness River. Habitat complexity and opportunity also governed the distribution of juvenile salmonids within the tidal marshes. I also sampled three regions of the estuary with a beach seine to investigate the nearshore distribution of juvenile salmonids within the Dungeness River estuary: the delta face, inner Bay, and outer Bay. Among the three regions, species composition was highly variable between 2006 and 2007. The most common salmonids encountered within the beach seine sites included Chinook salmon, chum salmon (O. kisutch), and pink salmon (O. gorbuscha). The relative abundance of salmonids was highest near the delta face and lowest within the outer bay area. The landscape-scale distribution and habitat use of juvenile salmonids within the Dungeness River estuary is largely influenced by ecosystem connectivity, but is also linked to biotic characteristics of the fish (e.g., life history type and fish size). Although the Dungeness includes hydrogeomorphic characteristics (e.g., steep river gradient, composition of sand spits in the estuary) unique to other Pacific Northwest watersheds, this system produces a variety of life history types comparable to other estuaries. Understanding the mechanisms that drive the distribution of juvenile salmonids within the Dungeness will supply local resource managers with a baseline with which to establish ecosystem restoration goals.
Author: Coowe Walker Publisher: ISBN: Category : Fish communities Languages : en Pages : 120
Book Description
The study, the first scientific research on fish communities at this location, took place in the Fox River estuary located within the boundaries of the Kachemak Bay National Estuarine Research Reserve. This area is designated Fox River Flats State Critical Habitat Area. An emphasis was placed on patterns in diet and growth in the predominant juvenile salmon species, coho and sockeye.
Author: Michael Arbeider Publisher: ISBN: Category : Languages : en Pages : 111
Book Description
Estuaries are valuable nursery and stopover habitats that support mobile consumers during their ontogenetic migrations such as juvenile anadromous salmon. My first data chapter was an extensive field study that examined how two salmon and two small pelagic fish integrate with key prey across the estuary of the Skeena River. The different fishes selected different prey that were unevenly distributed across the estuary seascape in time and space; however, some prey were associated with biophysical factors like salinity and eelgrass. My next chapter compiled empirical published data on five species of juvenile salmon growth rates and residency durations. Several species had poor coverage of these aspects, but it was evident that different salmon species and life history strategies have different growth rates and residency durations in estuaries. Collectively, this work adds and organizes empirical support for valuing estuaries as important habitat for juvenile salmon.
Author: Publisher: ISBN: Category : Languages : en Pages : 19
Book Description
In 2002 with support from the U.S. Army Corps of Engineers (USACE), an interagency research team began investigating salmon life histories and habitat use in the lower Columbia River estuary to fill significant data gaps about the estuary's potential role in salmon decline and recovery . The Bonneville Power Administration (BPA) provided additional funding in 2004 to reconstruct historical changes in estuarine habitat opportunities and food web linkages of Columbia River salmon (Onchorhynchus spp.). Together these studies constitute the estuary's first comprehensive investigation of shallow-water habitats, including selected emergent, forested, and scrub-shrub wetlands. Among other findings, this research documented the importance of wetlands as nursery areas for juvenile salmon; quantified historical changes in the amounts and distributions of diverse habitat types in the lower estuary; documented estuarine residence times, ranging from weeks to months for many juvenile Chinook salmon (O. tshawytscha); and provided new evidence that contemporary salmonid food webs are supported disproportionately by wetland-derived prey resources. The results of these lower-estuary investigations also raised many new questions about habitat functions, historical habitat distributions, and salmon life histories in other areas of the Columbia River estuary that have not been adequately investigated. For example, quantitative estimates of historical habitat changes are available only for the lower 75 km of the estuary, although tidal influence extends 217 km upriver to Bonneville Dam. Because the otolith techniques used to reconstruct salmon life histories rely on detection of a chemical signature (strontium) for salt water, the estuarine residency information we have collected to date applies only to the lower 30 or 35 km of the estuary, where fish first encounter ocean water. We lack information about salmon habitat use, life histories, and growth within the long tidal-fresh reaches of the main-stem river and many tidally-influenced estuary tributaries. Finally, our surveys to date characterize wetland habitats within island complexes distributed in the main channel of the lower estuary. Yet some of the most significant wetland losses have occurred along the estuary's periphery, including shoreline areas and tributary junctions. These habitats may or may not function similarly as the island complexes that we have surveyed to date. In 2007 we initiated a second phase of the BPA estuary study (Phase II) to address specific uncertainties about salmon in tidal-fresh and tributary habitats of the Columbia River estuary. This report summarizes 2007 and 2008 Phase II results and addresses three principal research questions: (1) What was the historic distribution of estuarine and floodplain habitats from Astoria to Bonneville Dam? (2) Do individual patterns of estuarine residency and growth of juvenile Chinook salmon vary among wetland habitat types along the estuarine tidal gradient? (3) Are salmon rearing opportunities and life histories in the restoring wetland landscape of lower Grays River similar to those documented for island complexes of the main-stem estuary? Phase II extended our analysis of historical habitat distribution in the estuary above Rkm 75 to near Bonneville Dam. For this analysis we digitized the original nineteenth-century topographic (T-sheets) and hydrographic (H-sheets) survey maps for the entire estuary. Although all T-sheets (Rkm 0 to Rkm 206) were converted to GIS in 2005 with support for the USACE estuary project, final reconstruction of historical habitats throughout the estuary requires completion of the remaining H-sheet GIS maps above Rkm 75 and their integration with the T-sheets. This report summarizes progress to date on compiling the upper estuary H-sheets above Rkm 75. For the USACE estuary project, we analyzed otoliths from Chinook salmon collected near the estuary mouth in 2003-05 to estimate variability in estuary residence times among juvenile out migrants. In Phase II we expanded these analyses to compare growth and residency among individuals collected in tidal-fresh water wetlands of the lower main-stem estuary. Although no known otolith structural or chemical indicators currently exist to define entry into tidal fresh environments, our previous analyses indicate that otolith barium concentrations frequently increase before individuals encounter salt water. Here we evaluate whether otolith barium levels may provide a valid indicator of tidal fresh water entry by Columbia River Chinook salmon. We also examine otolith growth increments to quantify and compare recent (i.e., the previous 30 d) growth rates among individuals sampled in different wetland habitats along the estuarine tidal gradient.
Author: Ciara Sharpe
Author: Ciara Sharpe
Author: Nichole K. Sather
Author: Coowe Walker
Author: Michael Arbeider
Author: 
Author: George Curtis Roegner
Author: D. W. Reiser
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Author: George Curtis Roegner
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