Habitat Utilizaton and Foraging Habits of Juvenile Salmonids (Oncorhynchus Spp.) in the Smith River Estuary, California PDF Download

Author: Rebecca M. Quiñones
Publisher:
ISBN:
Category : Salmonidae
Languages : en
Pages : 192

View

Book Description

Author: David Zajanc
Publisher:
ISBN:
Category : Chinook salmon
Languages : en
Pages : 186

View

Book Description

Author: Michael E. McCain
Publisher:
ISBN:
Category : Chinook salmon
Languages : en
Pages : 9

View

Book Description

Author: Gary D. Reedy
Publisher:
ISBN:
Category : Chinook salmon
Languages : en
Pages : 274

View

Book Description

Author: Pamela Ann Petrusso
Publisher:
ISBN:
Category : Chinook salmon
Languages : en
Pages : 232

View

Book Description

Author: Nichole K. Sather
Publisher:
ISBN:
Category : Pacific salmon
Languages : en
Pages : 256

View

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: Terry A. Jackson
Publisher:
ISBN:
Category : Chinook salmon
Languages : en
Pages : 244

View

Book Description
Habitats for juvenile chinook salmon (Oncorhynchus tshawytscha) were observed at a high flow during the spring of 1989 and at a low flow during the spring of 1991 in the lower American River of California. Parameters of microhabitats in eight macrohabitats were measured. Mean column water velocity and total water depth variables were used to statistically compare juvenile chinook salmon microhabitat distributions between and among macrohabitat type/reach and flow combinations. Using mean column water velocity and total water depth as independent variables, each macrohabitat type/reach appeared to be unique. Mean column water velocity seemed to be a better descriptor of juvenile chinook salmon habitat selection than was total water depth. Riffles appeared to be the preferred macrohabitats for large non-schooling chinook salmon at both flow levels. Root wads, woody debris, and submerged terrestrial vegetation were utilized extensively and provided a significant cover for schooling chinook salmon during the high flow period. Habitat utilization by chinook salmon appears to be influenced by nonhydraulic variables. Application of models in current instream flow studies need to include factors such as water temperature and aquatic insect production.

Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 52

View

Book Description
From 2002 through 2006 we investigated historical and contemporary variations in juvenile Chinook salmon Oncorhynchus tshawytscha life histories, habitat associations, and food webs in the lower Columbia River estuary (mouth to rkm 101). At near-shore beach-seining sites in the estuary, Chinook salmon occurred during all months of the year, increasing in abundance from January through late spring or early summer and declining rapidly after July. Recently emerged fry dispersed throughout the estuary in early spring, and fry migrants were abundant in the estuary until April or May each year. Each spring, mean salmon size increased from the tidal freshwater zone to the estuary mouth; this trend may reflect estuarine growth and continued entry of smaller individuals from upriver. Most juvenile Chinook salmon in the mainstem estuary fed actively on adult insects and epibenthic amphipods Americorophium spp. Estimated growth rates of juvenile Chinook salmon derived from otolith analysis averaged 0.5 mm d-1, comparable to rates reported for juvenile salmon Oncorhynchus spp. in other Northwest estuaries. Estuarine salmon collections were composed of representatives from a diversity of evolutionarily significant units (ESUs) from the lower and upper Columbia Basin. Genetic stock groups in the estuary exhibited distinct seasonal and temporal abundance patterns, including a consistent peak in the Spring Creek Fall Chinook group in May, followed by a peak in the Western Cascades Fall Chinook group in July. The structure of acanthocephalan parasite assemblages in juvenile Chinook salmon from the tidal freshwater zone exhibited a consistent transition in June. This may have reflected changes in stock composition and associated habitat use and feeding histories. From March through July, subyearling Chinook salmon were among the most abundant species in all wetland habitat types (emergent, forested, and scrub/shrub) surveyed in the lower 100 km of the estuary. Salmon densities within wetland habitats fell to low levels by July, similar to the pattern observed at mainstem beach-seining sites and coincident with high water temperatures that approached or exceeded 19 C by mid-summer. Wetland habitats were used primarily by small subyearling Chinook salmon, with the smallest size ranges (i.e., rarely exceeding 70 mm by the end of the wetland rearing season) at scrub/shrub forested sites above rkm 50. Wetland sites of all types were utilized by a diversity of genetic stock groups, including less abundant groups such as Interior Summer/Fall Chinook.

Author: Crystal R. Hackmann
Publisher:
ISBN:
Category : Chinook salmon
Languages : en
Pages : 184

View

Book Description
Estuaries provide juvenile salmonids with highly productive feeding grounds, refugia from tidal fluctuations and predators, and acclimation areas for smoltification. However, these dynamic, fluctuating salinity environments may also be physiologically stressful to growing juvenile fish. In order to evaluate the costs and benefits of estuarine marshes to juvenile Chinook salmon, I observed habitat use, diet, and growth of fish in the Nehalem Estuary on the Oregon coast. I also examined physiological costs associated with salmon living in fluctuating salinities and growth rates in laboratory experiments. I collected growth, diet and osmoregulation information from juvenile Chinook salmon in three tidal marsh sites in the Nehalem Bay and from juveniles in the Nehalem River. Stomach contents indicated that a high proportion of the diet is derived from terrestrial prey. These allochthonous prey resources likely become available during the flood stages of tidal cycles when drift, emergent and terrestrial insects would become available from the grasses surrounding the water. This field study confirmed that juvenile Chinook salmon utilized fluctuating salinity habitats to feed on a wide range of items including terrestrial-derived resources. Although field studies indicate that fish in estuarine habitats grow well and have access to quality prey resources, experimental manipulations of salinities were used to quantify the physiological costs of residing in the freshwater-saltwater transitional zone. In the laboratory, I designed an experiment to investigate the physiological responses to fluctuating salinities. Experimental treatments consisted of freshwater (FW), saltwater (SW) (22-25%o); and a fluctuating salinity (SW/FW) (2 - 25%o). These treatments were based on typical salinity fluctuations found in estuarine habitats. I measured length, weight, plasma electrolytes and cortisol concentrations for indications of growth and osmoregulatory function. The fluctuating salinity treatment had a negative effect on growth rate and initial osmoregulatory ability when compared with constant freshwater and saltwater treatments. The results indicated that fluctuating salinities had a small but marginally significant reduction in growth rate, possibly due to the additional energetic requirements of switching between hyper- and hypo-osmoregulation. However, 24-hour saltwater challenge results indicated that all fish were capable of osmoregulating in full-strength seawater. In a second experiment, I manipulated feed consumption rates of juvenile spring Chinook salmon to investigate the effects of variable growth rates on osmoregulatory ability and to test the validity of RNA:DNA ratios as indication of recent growth. The treatments consisted of three different feeding rates: three tanks of fish fed 0.7 5% (LOW) body weight; three tanks fed 3% (HIGH) body weight; and three tanks were fasted (NONE) during the experiment. These laboratory results showed a significant difference in the osmoregulatory ability of the NONE treatment compared to the LOW and HIGH treatments which indicates that a reduction in caloric intake significantly effected osmoregulatory capabilities during a 24 hour saltwater challenge. Furthermore, this suggests that there is a minimum energetic requirement in order to maintain proper ion- and osmoregulation in marine conditions. Estuarine marshes have the potential to provide productive feeding grounds with sufficient prey input from terrestrial systems. However, utilization of these marshes in sub-optimal conditions could alter behavior or impair physiological condition of juvenile Chinook salmon prior to their seaward migration by providing insufficient prey resources in a potentially stressful, fluctuating environment. Therefore, the physiological costs associated with estuarine habitat use should be well understood in order to aid future restoration planning.

Author: Lindsay J. Adrean
Publisher:
ISBN:
Category : Caspian tern
Languages : en
Pages : 123

View

Book Description
Brooks Island, located in central San Francisco Bay, California, currently supports the largest breeding colony of Caspian terns (Hydroprogne caspia) in the Bay Area, and is one of several proposed relocation sites for some Caspian terns from the world's largest colony in the Columbia River estuary of Oregon. Juvenile salmonids have been identified in the diet of Caspian terns nesting at Brooks Island, so I investigated whether the colony, at its current or an enhanced size, poses a threat to the recovery of several runs of salmonids (Oncorhynchus spp.) in San Francisco Bay that are listed under the U.S. Endangered Species Act (ESA). I also examined the foraging ecology of Brooks Island Caspian terns to 1) determine whether the colony is suitable for expansion based on availability of forage fish resources, a factor potentially limiting the size and productivity of the colony, and 2) investigate how Caspian terns nesting at this colony exploit forage fish resources. I used a bioenergetics modeling approach, employing estimates of tern energy requirements and proportions of energy supplied by various prey types, to estimate consumption of juvenile salmonids by Caspian terns nesting on Brooks Island during 2008 and 2009. Estimated salmonid consumption was 205,000 smolts (95% CI: 175,000 - 245,000 smolts) in 2008 and 167,000 smolts (95% CI: 144,000 - 191,000 smolts) in 2009. Predation rates on ESA-listed Central Valley spring-run Chinook salmon (O. tshawytscha; 0.08%) were lower than those on unlisted fall-run Chinook salmon (1.0%). Average per capita predation rates on juvenile salmonids by Brooks Island Caspian terns (2008: 126 fish; 2009: 123 fish) were less than half those of Caspian terns nesting in the Columbia River estuary. If the current downward trend in the number of Caspian terns nesting on Brooks Island continues until the colony is no longer extant, the resulting declines in predation on salmonids would lead to increases in annual population growth rates ([delta lambda]) of salmonid runs of just small fractions of one percentage point. The proposed enhancement of the Brooks Island Caspian tern colony to 3,000 individuals would at most cause declines in annual population growth rates of 0.3% for fall-run Chinook salmon and 0.02% for threatened spring-run Chinook salmon, assuming that smolt mortality from tern predation is 100% additive. This level of impact to the ESA-listed spring-run Chinook salmon stock is less than the level considered acceptable by the National Marine Fisheries Service ([delta lambda] = 0.05%). Radio-tracking of Caspian terns nesting on Brooks Island revealed that the maximum foraging distance from the colony was 80 km. The median foraging distance from the colony was greater in 2009 compared to 2008 (20.6 km vs. 14.0 km), average number of foraging trips per day was higher (4.4 vs. 3.4 foraging trips), and average adult colony attendance was lower (43% vs. 52% of daylight hours). These results indicate that the colony was more food-limited during the 2009 breeding season, concurrent with anomalous downwelling along the coast of northern California and reduced availability and size of marine forage fishes, such as herring, sardines, and anchovies. Caspian terns used a number of core foraging areas within 30 km of the Brooks Island colony, both inside and just outside the Bay. Two large core foraging areas were close to or overlapped with the release site for juvenile salmonids in eastern San Pablo Bay, where> 10 million hatchery-raised smolts were released from net pens during both the 2008 and 2009 tern nesting seasons. This finding supports the hypothesis that most juvenile salmonids consumed by terns nesting at the Brooks Island colony were captured at or near the release site. Individual Caspian terns displayed foraging site fidelity, suggesting that foraging at the release site for hatchery-raised salmonids was a learned behavior by some terns. The Brooks Island colony site is within foraging distance of adequate marine forage fish resources in most years, and Caspian terns nesting there are not dependent on juvenile salmonids as a food resource. Consumption of juvenile salmonids by Brooks Island terns would be largely curtailed by modification of hatchery release practices.