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• 111. [Article] Aspects of the foraging ecology of humpback whales (Megaptera novaeangliae) in Frederick Sound and Stephens Passage, Southeast Alaska

  The North Pacific humpback whale (Megaptera novaeangliae) population has been increasing at an average annual rate of ~6% since the early 1990s. In northern Southeast Alaska alone, there are now more whales ...

  Citation × Citation Citation Abstract Copy Title: Aspects of the foraging ecology of humpback whales (Megaptera novaeangliae) in Frederick Sound and Stephens Passage, Southeast Alaska Author: Szabo, Andrew, 1974- The North Pacific humpback whale (Megaptera novaeangliae) population has been increasing at an average annual rate of ~6% since the early 1990s. In northern Southeast Alaska alone, there are now more whales than estimated for the entire North Pacific several decades ago. An understanding of how this growing population is repopulating traditional foraging grounds will benefit from detailed investigations of their prey preferences and trends in whale abundance and distribution relative to those prey. This dissertation examines these issues from late May until early September 2008 in Frederick Sound and Stephens Passage, a Southeast Alaskan feeding area historically used by humpback whales. The foundation for the study is an analysis of the life histories and abundance patterns of euphausiids, the principal prey of humpbacks in the area, during late spring and summer. Four species, Thysanoessa raschii, T. longipes, T. spinifera, and Euphausia pacifica, were identified in plankton net samples collected at random locations throughout the study site (n = 49) and in locations where a strong scattering layer was observed on a 120 kHz echosounder (n = 48). Both sample types varied in euphausiid species composition. Abundance patterns of immature euphausiids coupled with observations of females carrying spermatophores indicated differences between species in spawning schedules. Thysanoessa spp. began spawning in early April with the spring phytoplankton bloom and continued until late June, whereas E. pacifica began spawning in early June and continued until late August. This protracted recruitment of immature euphausiids was geographically widespread throughout the summer in contrast to adults, which, although present all summer, were found primarily in slope and shallow (< 100 m) areas. To determine if humpback whales preferred one euphausiid species or life-stage over another, net sample and hydroacoustic data collected in the vicinity of whales were compared to similar data collected in random locations throughout the study site. This revealed that whales targeted dense aggregations of adult euphausiids, but did not discriminate between the various species, which was surprising because of presumed differences in the energy density linked to their different spawning schedules. Additionally, whales did not spend time in areas with concentrations of immature euphausiids, which were likely not large enough during the study period to be suitable prey. With this preference for adult euphausiids, the abundance and distribution patterns of humpbacks were examined in relation to prey availability. Whale abundance was lowest at the beginning of the study in late May at ca. 68 whales and peaked in late July at ca. 228 animals – approximately 12% of the region’s estimated abundance for the study year. This study did not detect a concomitant increase in the availability of adult euphausiids, which is unsurprising since immature euphausiids would not recruit into the adult population until after the end of the study, and post-spawning mortality and predation pressure is presumably high during this time. Instead, whales clustered increasingly around comparatively fewer prey as the summer progressed. These observations, combined with a plateau in whale abundance after July, suggest that their abundance in the area was limited by euphausiid availability. Estimates of whales using the study site during the summer have remained similar over several decades despite a dramatic increase in humpback numbers in Southeast Alaska and elsewhere in the North Pacific. The results from this study suggest that, although the study site remains important seasonally to some whales, it is not a significant source of prey responsible for regional population growth in general. More likely, it is part of a network of feeding areas that has influenced the population trend. Further insight into these and the other issues raised in this dissertation could come from several additional analyses. An extended sampling season that captures the recruitment of immature euphausiids into the adult population would reveal whether a given year's prey cohort represents an important resource to whales in that same year, which has potential implications for interpreting mid-late season whale abundance patterns. As well, a photo-identification study would be useful in characterizing whale residency patterns and determining whether the abundance trends reflect a relatively small subset of the regional population using the area for most of the season or a continuous flow of a larger portion of the population. Finally, similar analyses as those outlined here but conducted in other areas within the region would provide additional insight into the network’s capacity to support the recovering whale population. Title: Aspects of the foraging ecology of humpback whales (Megaptera novaeangliae) in Frederick Sound and Stephens Passage, Southeast Alaska Author: Szabo, Andrew, 1974- The North Pacific humpback whale (Megaptera novaeangliae) population has been increasing at an average annual rate of ~6% since the early 1990s. In northern Southeast Alaska alone, there are now more whales than estimated for the entire North Pacific several decades ago. An understanding of how this growing population is repopulating traditional foraging grounds will benefit from detailed investigations of their prey preferences and trends in whale abundance and distribution relative to those prey. This dissertation examines these issues from late May until early September 2008 in Frederick Sound and Stephens Passage, a Southeast Alaskan feeding area historically used by humpback whales. The foundation for the study is an analysis of the life histories and abundance patterns of euphausiids, the principal prey of humpbacks in the area, during late spring and summer. Four species, Thysanoessa raschii, T. longipes, T. spinifera, and Euphausia pacifica, were identified in plankton net samples collected at random locations throughout the study site (n = 49) and in locations where a strong scattering layer was observed on a 120 kHz echosounder (n = 48). Both sample types varied in euphausiid species composition. Abundance patterns of immature euphausiids coupled with observations of females carrying spermatophores indicated differences between species in spawning schedules. Thysanoessa spp. began spawning in early April with the spring phytoplankton bloom and continued until late June, whereas E. pacifica began spawning in early June and continued until late August. This protracted recruitment of immature euphausiids was geographically widespread throughout the summer in contrast to adults, which, although present all summer, were found primarily in slope and shallow (< 100 m) areas. To determine if humpback whales preferred one euphausiid species or life-stage over another, net sample and hydroacoustic data collected in the vicinity of whales were compared to similar data collected in random locations throughout the study site. This revealed that whales targeted dense aggregations of adult euphausiids, but did not discriminate between the various species, which was surprising because of presumed differences in the energy density linked to their different spawning schedules. Additionally, whales did not spend time in areas with concentrations of immature euphausiids, which were likely not large enough during the study period to be suitable prey. With this preference for adult euphausiids, the abundance and distribution patterns of humpbacks were examined in relation to prey availability. Whale abundance was lowest at the beginning of the study in late May at ca. 68 whales and peaked in late July at ca. 228 animals – approximately 12% of the region’s estimated abundance for the study year. This study did not detect a concomitant increase in the availability of adult euphausiids, which is unsurprising since immature euphausiids would not recruit into the adult population until after the end of the study, and post-spawning mortality and predation pressure is presumably high during this time. Instead, whales clustered increasingly around comparatively fewer prey as the summer progressed. These observations, combined with a plateau in whale abundance after July, suggest that their abundance in the area was limited by euphausiid availability. Estimates of whales using the study site during the summer have remained similar over several decades despite a dramatic increase in humpback numbers in Southeast Alaska and elsewhere in the North Pacific. The results from this study suggest that, although the study site remains important seasonally to some whales, it is not a significant source of prey responsible for regional population growth in general. More likely, it is part of a network of feeding areas that has influenced the population trend. Further insight into these and the other issues raised in this dissertation could come from several additional analyses. An extended sampling season that captures the recruitment of immature euphausiids into the adult population would reveal whether a given year's prey cohort represents an important resource to whales in that same year, which has potential implications for interpreting mid-late season whale abundance patterns. As well, a photo-identification study would be useful in characterizing whale residency patterns and determining whether the abundance trends reflect a relatively small subset of the regional population using the area for most of the season or a continuous flow of a larger portion of the population. Finally, similar analyses as those outlined here but conducted in other areas within the region would provide additional insight into the network’s capacity to support the recovering whale population. Close

• 112. [Article] GIS modeling of potential marine protected areas in the Northwest Atlantic via biological and socioeconomic parameters

  Overfishing of our national marine resources has degraded some of the most productive fishing regions in the Northwest Atlantic Ocean, most notably the Gulf of Maine and Georges Bank. These regions may ...

  Citation × Citation Citation Abstract Copy Title: GIS modeling of potential marine protected areas in the Northwest Atlantic via biological and socioeconomic parameters Author: Keith, Charles M. Overfishing of our national marine resources has degraded some of the most productive fishing regions in the Northwest Atlantic Ocean, most notably the Gulf of Maine and Georges Bank. These regions may have shifted from productive trophic regimes to a less than optimal state therefore reducing fishers’ catches and associated revenue from commercially targeted species (Sinclair and Murawski, 1997, Jennings et al, 2001). Marine protected areas (MPAs) have been offered as an effective management tool to preserve biodiversity, enhance commercial fisheries, and protect against poor decisions in fisheries management (Bohnsack, 1999). Geographic information systems (GIS) bring together the fields of geography and fisheries management to help build a better understanding of the spatial interactions of complex marine environments (e.g., Kracker, 1999). Using GIS and spatial management such as MPAs can help fishery managers conserve and improve the population status of important biological resources while helping to preserve commercial fishing, an important social and political industry in New England. Incorporating the needs of stakeholders in management decisions is necessary in order to implement an effective fisheries management strategy (e.g., Malakoff, 2002). This study used a weighted optimization raster model in a GIS to compare biological significant regions, which were composed of biodiversity estimates and spawning and juvenile habitats, to important commercial fishing grounds in the Gulf of Maine and Georges Bank. Biodiversity, spawning and juvenile data values were derived from fishery independent data collected by 2 the National Marine Fisheries Service in Woods Hole, MA. The essential commercial fishing zones were created from Vessel Trip Reports, which are derived directly from reports sent in by federally permitted fishers. The weighted model compares the biologically important resources from an area, or cell, to the level of commercial fishing occurring in the same cell using simple mathematically algorithms in map algebra. The model output shows where placement of MPAs might be most beneficial in order to conserve marine resources and enhance fisheries, as well as areas where fishing is more suitable. Output can be viewed in multiple ways, a spectrum of values ranging from negative numbers to positive ones or simply as areas important for the fishing community or potential MPA. The more negative the value in the spectrum output then the more important the area would be for fishers and conversely the more positive the output then the more suitable the area would be for possible MPA designation. The optimization model can be tuned to meet management goals and objectives by adjusting the weighting scenarios for the input variables. The model design can be used for multiple species and ecosystem management or to protect specifically targeted species of particular concern. Managers may use the output to delineate MPAs in a variety of ways depending on the conditions of the resources and the prospects of the fishing community. Managers will enjoy greater success as the needs of both fishers and biological resources are met. Title: GIS modeling of potential marine protected areas in the Northwest Atlantic via biological and socioeconomic parameters Author: Keith, Charles M. Overfishing of our national marine resources has degraded some of the most productive fishing regions in the Northwest Atlantic Ocean, most notably the Gulf of Maine and Georges Bank. These regions may have shifted from productive trophic regimes to a less than optimal state therefore reducing fishers’ catches and associated revenue from commercially targeted species (Sinclair and Murawski, 1997, Jennings et al, 2001). Marine protected areas (MPAs) have been offered as an effective management tool to preserve biodiversity, enhance commercial fisheries, and protect against poor decisions in fisheries management (Bohnsack, 1999). Geographic information systems (GIS) bring together the fields of geography and fisheries management to help build a better understanding of the spatial interactions of complex marine environments (e.g., Kracker, 1999). Using GIS and spatial management such as MPAs can help fishery managers conserve and improve the population status of important biological resources while helping to preserve commercial fishing, an important social and political industry in New England. Incorporating the needs of stakeholders in management decisions is necessary in order to implement an effective fisheries management strategy (e.g., Malakoff, 2002). This study used a weighted optimization raster model in a GIS to compare biological significant regions, which were composed of biodiversity estimates and spawning and juvenile habitats, to important commercial fishing grounds in the Gulf of Maine and Georges Bank. Biodiversity, spawning and juvenile data values were derived from fishery independent data collected by 2 the National Marine Fisheries Service in Woods Hole, MA. The essential commercial fishing zones were created from Vessel Trip Reports, which are derived directly from reports sent in by federally permitted fishers. The weighted model compares the biologically important resources from an area, or cell, to the level of commercial fishing occurring in the same cell using simple mathematically algorithms in map algebra. The model output shows where placement of MPAs might be most beneficial in order to conserve marine resources and enhance fisheries, as well as areas where fishing is more suitable. Output can be viewed in multiple ways, a spectrum of values ranging from negative numbers to positive ones or simply as areas important for the fishing community or potential MPA. The more negative the value in the spectrum output then the more important the area would be for fishers and conversely the more positive the output then the more suitable the area would be for possible MPA designation. The optimization model can be tuned to meet management goals and objectives by adjusting the weighting scenarios for the input variables. The model design can be used for multiple species and ecosystem management or to protect specifically targeted species of particular concern. Managers may use the output to delineate MPAs in a variety of ways depending on the conditions of the resources and the prospects of the fishing community. Managers will enjoy greater success as the needs of both fishers and biological resources are met. Close

• 113. [Article] Using parasite community data and population genetics for assessing Pacific sardine (Sardinops sagax) population structure along the west coast of North America

  Pacific sardines (Sardinops sagax) are an economically and ecologically important forage fish which transfer energy from planktonic primary producers and secondary consumers to upper trophic predators. ...

  Citation × Citation Citation Abstract Copy Title: Using parasite community data and population genetics for assessing Pacific sardine (Sardinops sagax) population structure along the west coast of North America Author: Baldwin, Rebecca E. B. Pacific sardines (Sardinops sagax) are an economically and ecologically important forage fish which transfer energy from planktonic primary producers and secondary consumers to upper trophic predators. Previous genetics studies of Pacific sardine suggested a panmictic population with a shallow genetic structure. However, more than one subpopulation within the Central California Offshore management unit may exist based on recovering larger individuals at higher latitudes and a temporal difference in sardine spawning off Southern California and the Pacific Northwest. Potential for separate sardine subpopulations questions the long-standing paradigm of an annual migration of individuals to feeding grounds off the Pacific Northwest in the summer with migrants returning to Southern California in the fall to spawn the following spring. This study applied parasite community analyses and population genetics techniques to assess migration patterns and stock structure of Pacific sardine in the California Current from Vancouver Island, British Columbia, Canada to San Diego, California, USA. A coastwide sardine migration is supported by the geographical distribution of Myosaccium ecaude (Trematoda), but a second migration pattern was identified within the Pacific Northwest from the geographic distribution of Lecithaster gibbosus (Trematoda). Population genetics studies identified a panmictic distribution for: 1) the trematode M. ecaude using a 283bp portion of the NADH-dehydrogenase subunit 1 (ND1) mitochondrial DNA (mtDNA) gene; and 2) three species of Anisakis nematodes (A. simplex s.s., A. pegreffii, and A. simplex 'C') using a 524bp portion of the cytochrome c oxidase 2 (cox2) mtDNA gene. These results suggest that the extensive movement of all of the potential hosts utilized by these parasites, the limited oceanographic barriers, and complexity in the California Current are not preventing the mixing of M. ecaude or Anisakis species populations. The diversity and availability of fish and cetacean species that undergo extensive migrations along the full length of the California Current system may enable large geographically distributed population sizes of these parasite species. We thus cannot confirm the existence of separate Pacific sardine subpopulations within the California Current by the occurrence of parasite communities or the population genetics analyses of M. ecaude or the three Anisakis species. Title: Using parasite community data and population genetics for assessing Pacific sardine (Sardinops sagax) population structure along the west coast of North America Author: Baldwin, Rebecca E. B. Pacific sardines (Sardinops sagax) are an economically and ecologically important forage fish which transfer energy from planktonic primary producers and secondary consumers to upper trophic predators. Previous genetics studies of Pacific sardine suggested a panmictic population with a shallow genetic structure. However, more than one subpopulation within the Central California Offshore management unit may exist based on recovering larger individuals at higher latitudes and a temporal difference in sardine spawning off Southern California and the Pacific Northwest. Potential for separate sardine subpopulations questions the long-standing paradigm of an annual migration of individuals to feeding grounds off the Pacific Northwest in the summer with migrants returning to Southern California in the fall to spawn the following spring. This study applied parasite community analyses and population genetics techniques to assess migration patterns and stock structure of Pacific sardine in the California Current from Vancouver Island, British Columbia, Canada to San Diego, California, USA. A coastwide sardine migration is supported by the geographical distribution of Myosaccium ecaude (Trematoda), but a second migration pattern was identified within the Pacific Northwest from the geographic distribution of Lecithaster gibbosus (Trematoda). Population genetics studies identified a panmictic distribution for: 1) the trematode M. ecaude using a 283bp portion of the NADH-dehydrogenase subunit 1 (ND1) mitochondrial DNA (mtDNA) gene; and 2) three species of Anisakis nematodes (A. simplex s.s., A. pegreffii, and A. simplex 'C') using a 524bp portion of the cytochrome c oxidase 2 (cox2) mtDNA gene. These results suggest that the extensive movement of all of the potential hosts utilized by these parasites, the limited oceanographic barriers, and complexity in the California Current are not preventing the mixing of M. ecaude or Anisakis species populations. The diversity and availability of fish and cetacean species that undergo extensive migrations along the full length of the California Current system may enable large geographically distributed population sizes of these parasite species. We thus cannot confirm the existence of separate Pacific sardine subpopulations within the California Current by the occurrence of parasite communities or the population genetics analyses of M. ecaude or the three Anisakis species. Close

• 114. [Article] Natural history and ecology of larval Lost River suckers and larval shortnose suckers in the Williamson River-Upper Klamath Lake System

  We monitored larval Lost River and shortnose suckers from natal beds in the Williamson and Sprague rivers to nursery grounds in Upper Klamath Lake. Downstream movements occurred at night, in the middle ...

  Citation × Citation Citation Abstract Copy Title: Natural history and ecology of larval Lost River suckers and larval shortnose suckers in the Williamson River-Upper Klamath Lake System Author: Cooperman, Michael S. We monitored larval Lost River and shortnose suckers from natal beds in the Williamson and Sprague rivers to nursery grounds in Upper Klamath Lake. Downstream movements occurred at night, in the middle of the channel, and on the falling limb of the hydrograph. Ages, sizes, and developmental stages of larvae from spawning beds and the river mouth were similar, while larvae collected contemporaneously from the lake tended to be larger and better fed. Our results indicate in-river rearing was rare, that a rapid outmigration to the lake was favorable for larval survival, and that modification of the lower Williamson River does not appear to have prohibited rapid entry or preclude access to Upper Klamath Lake. Within the Williamson River and Upper Klamath Lake, emergent macrophytes supported significantly higher abundance, larger mean sizes, and better fed larvae than submerged macrophytes, woody vegetation, or open water areas. Analysis of seven years of larval sucker production and survival corroborated the habitat analysis by identifying a positive relationship with emergent macrophyte availability as well as a positive relationship with air temperature and a negative relationship with high wind. These findings illustrate the importance of fast growth, appropriate habitat and calm hydrological conditions for larvae, and are highly consistent with other larval fish studies. Title: Natural history and ecology of larval Lost River suckers and larval shortnose suckers in the Williamson River-Upper Klamath Lake System Author: Cooperman, Michael S. We monitored larval Lost River and shortnose suckers from natal beds in the Williamson and Sprague rivers to nursery grounds in Upper Klamath Lake. Downstream movements occurred at night, in the middle of the channel, and on the falling limb of the hydrograph. Ages, sizes, and developmental stages of larvae from spawning beds and the river mouth were similar, while larvae collected contemporaneously from the lake tended to be larger and better fed. Our results indicate in-river rearing was rare, that a rapid outmigration to the lake was favorable for larval survival, and that modification of the lower Williamson River does not appear to have prohibited rapid entry or preclude access to Upper Klamath Lake. Within the Williamson River and Upper Klamath Lake, emergent macrophytes supported significantly higher abundance, larger mean sizes, and better fed larvae than submerged macrophytes, woody vegetation, or open water areas. Analysis of seven years of larval sucker production and survival corroborated the habitat analysis by identifying a positive relationship with emergent macrophyte availability as well as a positive relationship with air temperature and a negative relationship with high wind. These findings illustrate the importance of fast growth, appropriate habitat and calm hydrological conditions for larvae, and are highly consistent with other larval fish studies. Close

• 115. [Article] Developing a predator-prey model for the hake and blue whiting Spanish fisheries

  The aim of this work is to develop a predator-prey model for two species of commercial importance captured by the Spanish fishing fleet in the National Fishing Ground (ICES areas VIIIc and IXa). In this ...

  Citation × Citation Citation Abstract Copy Title: Developing a predator-prey model for the hake and blue whiting Spanish fisheries Author: Perez-Perez, Marcos, Varela-Lafuente, Manuel, Garza-Gil, Dolores, Torralba-Cano, Julia The aim of this work is to develop a predator-prey model for two species of commercial importance captured by the Spanish fishing fleet in the National Fishing Ground (ICES areas VIIIc and IXa). In this model, the Southern hake (Merluccius merluccius) represents the predator, and the blue whiting (Micromesistius poutassou) is the prey. Blue whiting is the hake’s main prey in the study area, and it represents about 40% of the Southern hake diet. Both the predator and prey population dynamics follow the Lotka-Volterra formulation, and population dynamics are assumed as logistic, with two interaction coefficients: α is the effect of a unit change in the prey on the percent growth rate of the predator and β is the attack rate or searching efficiency of the predator. The populations interact randomly in proportion to population density. Logistic predator-prey equations were applied to the Southern hake and blue whiting stocks, including biomass, intrinsic rates of growth, carrying capacity and capture for both species. The goal is to maximize the present value of profit, forming the current value Hamiltonian for the maximization problem. Capture costs and prices of hake and blue whiting and discount rate were introduced at this point. Landings and SSB (Spawning Stock Biomass) data from both stocks over the period 1988-2010 were used for an econometric estimation by means of the Ordinary Least Squares method, to determine the form taken by the predator-prey net growth functions. Title: Developing a predator-prey model for the hake and blue whiting Spanish fisheries Author: Perez-Perez, Marcos, Varela-Lafuente, Manuel, Garza-Gil, Dolores, Torralba-Cano, Julia The aim of this work is to develop a predator-prey model for two species of commercial importance captured by the Spanish fishing fleet in the National Fishing Ground (ICES areas VIIIc and IXa). In this model, the Southern hake (Merluccius merluccius) represents the predator, and the blue whiting (Micromesistius poutassou) is the prey. Blue whiting is the hake’s main prey in the study area, and it represents about 40% of the Southern hake diet. Both the predator and prey population dynamics follow the Lotka-Volterra formulation, and population dynamics are assumed as logistic, with two interaction coefficients: α is the effect of a unit change in the prey on the percent growth rate of the predator and β is the attack rate or searching efficiency of the predator. The populations interact randomly in proportion to population density. Logistic predator-prey equations were applied to the Southern hake and blue whiting stocks, including biomass, intrinsic rates of growth, carrying capacity and capture for both species. The goal is to maximize the present value of profit, forming the current value Hamiltonian for the maximization problem. Capture costs and prices of hake and blue whiting and discount rate were introduced at this point. Landings and SSB (Spawning Stock Biomass) data from both stocks over the period 1988-2010 were used for an econometric estimation by means of the Ordinary Least Squares method, to determine the form taken by the predator-prey net growth functions. Close

• 116. [Article] Impacts of instream flows on the Colorado River Delta, Mexico : spatial vegetation change analysis and opportunities for restoration

  Until the 1930s, flows of the Colorado River maintained approximately 781,060 hectares of wetlands in its delta. These wetlands provided important feeding and nesting grounds for resident and migratory ...

  Citation × Citation Citation Abstract Copy Title: Impacts of instream flows on the Colorado River Delta, Mexico : spatial vegetation change analysis and opportunities for restoration Author: Zamora-Arroyo, Jose Francisco Until the 1930s, flows of the Colorado River maintained approximately 781,060 hectares of wetlands in its delta. These wetlands provided important feeding and nesting grounds for resident and migratory birds as well as spawning and protection habitat for many fish and other invertebrate species. However, the Delta's wetlands started to disappear as water was used for agricultural and urban uses in the United States and Mexico. The 1944 United States-Mexico water treaty, which allocates 1.8 million m³/year to Mexico, did not define a minimum flow to maintain the Delta's ecosystems. The resulting degraded Delta lead to the perception in the 1980s that the Delta was a dead ecosystem. This study investigates whether this "dead Delta" perception is valid. Its central hypothesis is that regenerated vegetation in riparian and flood plain zones is associated with surplus river flows during the 1990s. A vegetation analysis, using satellite imagery and field methods, shows that native trees have regenerated during the last 20 years, and now account for 23% of vegetation in a 100 km, non-perennial, stretch of river below the United States-Mexico border. A spatial trend analysis using multi-temporal data on percent vegetation cover indicates that there are 6,320 hectares that show a significant increasing trend (p-value<0.05) in vegetation cover, with the Delta's riparian zone having at least 18% of its area showing this trend. The study estimates that once in four years February to April flow of 300 million m³ (at 80-120 m³/s) is sufficient to germinate and establish new cohorts of native trees, and highlights the need for smaller but more periodic flows in order to maintain wetland areas. It is concluded that there is clear evidence of the resilience of the Delta's ecosystems and that the "dead Delta" perception is no longer valid. There exist critical habitat in the Delta that needs to be protected, while there also exist short and long term opportunities to ecologically enhance and expand current habitat. Hydrological and ecological studies are needed to estimate specific water requirements for these areas in order to efficiently target them for immediate and long term conservation actions. Title: Impacts of instream flows on the Colorado River Delta, Mexico : spatial vegetation change analysis and opportunities for restoration Author: Zamora-Arroyo, Jose Francisco Until the 1930s, flows of the Colorado River maintained approximately 781,060 hectares of wetlands in its delta. These wetlands provided important feeding and nesting grounds for resident and migratory birds as well as spawning and protection habitat for many fish and other invertebrate species. However, the Delta's wetlands started to disappear as water was used for agricultural and urban uses in the United States and Mexico. The 1944 United States-Mexico water treaty, which allocates 1.8 million m³/year to Mexico, did not define a minimum flow to maintain the Delta's ecosystems. The resulting degraded Delta lead to the perception in the 1980s that the Delta was a dead ecosystem. This study investigates whether this "dead Delta" perception is valid. Its central hypothesis is that regenerated vegetation in riparian and flood plain zones is associated with surplus river flows during the 1990s. A vegetation analysis, using satellite imagery and field methods, shows that native trees have regenerated during the last 20 years, and now account for 23% of vegetation in a 100 km, non-perennial, stretch of river below the United States-Mexico border. A spatial trend analysis using multi-temporal data on percent vegetation cover indicates that there are 6,320 hectares that show a significant increasing trend (p-value<0.05) in vegetation cover, with the Delta's riparian zone having at least 18% of its area showing this trend. The study estimates that once in four years February to April flow of 300 million m³ (at 80-120 m³/s) is sufficient to germinate and establish new cohorts of native trees, and highlights the need for smaller but more periodic flows in order to maintain wetland areas. It is concluded that there is clear evidence of the resilience of the Delta's ecosystems and that the "dead Delta" perception is no longer valid. There exist critical habitat in the Delta that needs to be protected, while there also exist short and long term opportunities to ecologically enhance and expand current habitat. Hydrological and ecological studies are needed to estimate specific water requirements for these areas in order to efficiently target them for immediate and long term conservation actions. Close

• 117. [Article] Juvenile Coho Salmon (Oncorhynchus kisutch) Diet in Brackish and Freshwater Habitats in the Stream-estuary Ecotones of Coos Bay, Oregon

  Loss of lowland estuarine and freshwater off-channel habitats along the Pacific Northwest coast has contributed to the decline of salmonid populations. These habitats serve as nursery grounds for juvenile ...

  Citation × Citation Citation Abstract Copy Title: Juvenile Coho Salmon (Oncorhynchus kisutch) Diet in Brackish and Freshwater Habitats in the Stream-estuary Ecotones of Coos Bay, Oregon Author: Mackereth, Kailan F. Loss of lowland estuarine and freshwater off-channel habitats along the Pacific Northwest coast has contributed to the decline of salmonid populations. These habitats serve as nursery grounds for juvenile salmonids providing them with food, winter shelter, and a transition zone between freshwater and saltwater. Lowland areas have undergone anthropogenic alterations (e.g., installation of tide gates, construction of dikes, channelization) to increase the net area of land suitable for agriculture and development resulting in watershed fragmentation and reduction in the amount of habitats with high intrinsic potential to support populations of juvenile salmonids. Until recent years, sub-yearling coho salmon found in lowland riverine habitats and estuarine marshes were assumed to have been displaced from optimal upland reaches by competition and high water discharge. Recent studies have concluded that early estuarine migrant behavior is volitional and these fish return as 20-40% of the spawning population, but there are few studies that delve into the capacity of estuarine habitat to support early estuarine life history strategies in systems heavily altered by human practices. This study documented differences in diet and condition factor (K) between sub-yearling and yearling coho salmon foraging concurrently in brackish or freshwater lowland habitat of the upper estuarine intertidal zone. Fish stomach contents were sampled by means of gastric lavage in three coastal lowland creeks in Coos Bay on the southern Oregon coast. Prey found in the samples were sorted, counted, identified, and dried to obtain dry weight biomass. Condition factor (K) and total dry weight prey biomass of fishes were not different between brackish and freshwater habitat; however, non-metric multidimensional scaling indicated that prey composition was substantially different between habitat and age class. These findings suggest that early migrating sub-yearlings and yearling smolts diverge in their diets whether they occupy the same or different habitats in the stream to estuary transition zone. Insects were important prey within the diets of yearling and sub-yearling freshwater foragers and sub-yearling brackish water foragers while crustaceans were important in the diets of yearling brackish water foragers. Future research exploring prey abundance and availability in relation to prey selected by juvenile coho salmon would denote habitat foraging quality and habitat exploitation by early estuarine migrants. Expanding this research to contrast natural intertidal habitats with those regulated by tide gates would be beneficial towards understanding the impact different styles of tide gates have on biotic communities and hydrological attributes (e.g., flow, chemistry, temperature, tidal exchange). Identification of factors that influence habitat selection in the stream-estuary ecotone by alternative early life history strategies of juvenile coho salmon is essential towards enhancing genetic diversity thereby strengthening the resiliency of the population. Title: Juvenile Coho Salmon (Oncorhynchus kisutch) Diet in Brackish and Freshwater Habitats in the Stream-estuary Ecotones of Coos Bay, Oregon Author: Mackereth, Kailan F. Loss of lowland estuarine and freshwater off-channel habitats along the Pacific Northwest coast has contributed to the decline of salmonid populations. These habitats serve as nursery grounds for juvenile salmonids providing them with food, winter shelter, and a transition zone between freshwater and saltwater. Lowland areas have undergone anthropogenic alterations (e.g., installation of tide gates, construction of dikes, channelization) to increase the net area of land suitable for agriculture and development resulting in watershed fragmentation and reduction in the amount of habitats with high intrinsic potential to support populations of juvenile salmonids. Until recent years, sub-yearling coho salmon found in lowland riverine habitats and estuarine marshes were assumed to have been displaced from optimal upland reaches by competition and high water discharge. Recent studies have concluded that early estuarine migrant behavior is volitional and these fish return as 20-40% of the spawning population, but there are few studies that delve into the capacity of estuarine habitat to support early estuarine life history strategies in systems heavily altered by human practices. This study documented differences in diet and condition factor (K) between sub-yearling and yearling coho salmon foraging concurrently in brackish or freshwater lowland habitat of the upper estuarine intertidal zone. Fish stomach contents were sampled by means of gastric lavage in three coastal lowland creeks in Coos Bay on the southern Oregon coast. Prey found in the samples were sorted, counted, identified, and dried to obtain dry weight biomass. Condition factor (K) and total dry weight prey biomass of fishes were not different between brackish and freshwater habitat; however, non-metric multidimensional scaling indicated that prey composition was substantially different between habitat and age class. These findings suggest that early migrating sub-yearlings and yearling smolts diverge in their diets whether they occupy the same or different habitats in the stream to estuary transition zone. Insects were important prey within the diets of yearling and sub-yearling freshwater foragers and sub-yearling brackish water foragers while crustaceans were important in the diets of yearling brackish water foragers. Future research exploring prey abundance and availability in relation to prey selected by juvenile coho salmon would denote habitat foraging quality and habitat exploitation by early estuarine migrants. Expanding this research to contrast natural intertidal habitats with those regulated by tide gates would be beneficial towards understanding the impact different styles of tide gates have on biotic communities and hydrological attributes (e.g., flow, chemistry, temperature, tidal exchange). Identification of factors that influence habitat selection in the stream-estuary ecotone by alternative early life history strategies of juvenile coho salmon is essential towards enhancing genetic diversity thereby strengthening the resiliency of the population. Close

• 118. [Article] Abundance, distribution, and migratory behavior of coastal cutthroat trout in two lower Columbia River tributaries

  Abstract -- Coastal cutthroat trout (Oncorhynchus clarki clarki) exhibit multiple life history types characterized by diverse migratory strategies, including anadromous, potomodromous, and freshwater resident ...

  Citation × Citation Citation Abstract Copy Title: Abundance, distribution, and migratory behavior of coastal cutthroat trout in two lower Columbia River tributaries Abstract -- Coastal cutthroat trout (Oncorhynchus clarki clarki) exhibit multiple life history types characterized by diverse migratory strategies, including anadromous, potomodromous, and freshwater resident forms. The factors contributing to life history variation within populations are not well understood, but probably are not strictly genetic (e.g. Johnson et al, in review). Variation in migration tendency within cutthroat populations may result from phenotype plasticity, influenced by density, frequency, or condition dependent processes (Hendry et al. 2004). For example, an individual cutthroat’s choice to migrate at a given time or age may be a response to environmental conditions mediated by a genetically determined reaction norm (Hutchings 2004). This report summarizes a study undertaken to describe the expression of migratory behavior within coastal cutthroat trout populations, the relationship among migratory and non-migratory individuals, and the implications of life history diversity for management of cutthroat trout in tributaries of the lower Columbia River. The relationship between resident and migratory populations (or resident and migratory individuals within populations) is of central importance for management of coastal cutthroat trout. In the lower Columbia River and southwest Washington State a proposed rule to list anadromous cutthroat as threatened under the federal Endangered Species Act (ESA) was withdrawn after the US Fish and Wildlife Service (USFWS) decided during its review process to include resident and anadromous forms in the same Distinct Population Segment (DPS). Debate over proposed ESA listing highlighted a general lack of knowledge about coastal cutthroat trout life history, relationships between resident and migratory forms, and estuarine habitat use in the lower Columbia River. In 2009, the decision not to list the DPS as threatened was remanded to the USFWS on the grounds that the Service had not adequately considered whether marine and estuarine habitats formed a significant portion of the range of the DPS (USFWS 2009). We evaluated the distribution and abundance of coastal cutthroat trout in Big Creek and Bear Creek, two tributaries that join the Columbia River estuary from the south (Oregon) side roughly 30 kilometers from the ocean, and monitored the migratory behavior of cutthroat that emigrated from these streams and entered the Columbia River estuary. Big Creek is an interesting system because a fish weir and diversion dam at an ODFW hatchery, established in 1941 and refurbished in 1957, prevent cutthroat trout from passing upstream, isolating the cutthroat spawning population above the hatchery. Despite this barrier to upstream migration, offspring of resident cutthroat in the upper watershed continue to “smolt” and migrate downstream past the barrier. We were interested in the fate of these fish and their contribution to the adult population. Bear Creek, on the other hand, has always had full access for anadromous cutthroat through much of its drainage. These two systems permit a comparison of life history characteristics, migration, and survival of coastal cutthroat rearing in streams above and below migration barriers, and provide study sites in Oregon to compliment research by USFWS of coastal cutthroat migration behavior in tributaries entering the estuary from the north side of the Columbia River (USFWS 2008; and see Hudson et al. 2008; Johnson 2008; Zydlewski et al. 2008). A major objective of our work in Big Creek and Bear Creek was to increase understanding of coastal cutthroat trout biology and the relationship between resident and migratory cutthroat in lower Columbia tributaries. Additionally, we sought to document habitat use in the Columbia River estuary by migrant cutthroat. Our specific objectives were to: • Estimate abundance of coastal cutthroat trout in Big Creek (above hatchery barrier) and Bear Creek (above and below a large dam) • Quantify the proportions of the cutthroat populations that are migratory, identify which individuals migrate and describe the timing of migration • Describe habitats used by anadromous migrants and characterize migration behavior within the Columbia River estuary • Measure estuarine/marine survival of anadromous individuals and document return to natal streams Title: Abundance, distribution, and migratory behavior of coastal cutthroat trout in two lower Columbia River tributaries Abstract -- Coastal cutthroat trout (Oncorhynchus clarki clarki) exhibit multiple life history types characterized by diverse migratory strategies, including anadromous, potomodromous, and freshwater resident forms. The factors contributing to life history variation within populations are not well understood, but probably are not strictly genetic (e.g. Johnson et al, in review). Variation in migration tendency within cutthroat populations may result from phenotype plasticity, influenced by density, frequency, or condition dependent processes (Hendry et al. 2004). For example, an individual cutthroat’s choice to migrate at a given time or age may be a response to environmental conditions mediated by a genetically determined reaction norm (Hutchings 2004). This report summarizes a study undertaken to describe the expression of migratory behavior within coastal cutthroat trout populations, the relationship among migratory and non-migratory individuals, and the implications of life history diversity for management of cutthroat trout in tributaries of the lower Columbia River. The relationship between resident and migratory populations (or resident and migratory individuals within populations) is of central importance for management of coastal cutthroat trout. In the lower Columbia River and southwest Washington State a proposed rule to list anadromous cutthroat as threatened under the federal Endangered Species Act (ESA) was withdrawn after the US Fish and Wildlife Service (USFWS) decided during its review process to include resident and anadromous forms in the same Distinct Population Segment (DPS). Debate over proposed ESA listing highlighted a general lack of knowledge about coastal cutthroat trout life history, relationships between resident and migratory forms, and estuarine habitat use in the lower Columbia River. In 2009, the decision not to list the DPS as threatened was remanded to the USFWS on the grounds that the Service had not adequately considered whether marine and estuarine habitats formed a significant portion of the range of the DPS (USFWS 2009). We evaluated the distribution and abundance of coastal cutthroat trout in Big Creek and Bear Creek, two tributaries that join the Columbia River estuary from the south (Oregon) side roughly 30 kilometers from the ocean, and monitored the migratory behavior of cutthroat that emigrated from these streams and entered the Columbia River estuary. Big Creek is an interesting system because a fish weir and diversion dam at an ODFW hatchery, established in 1941 and refurbished in 1957, prevent cutthroat trout from passing upstream, isolating the cutthroat spawning population above the hatchery. Despite this barrier to upstream migration, offspring of resident cutthroat in the upper watershed continue to “smolt” and migrate downstream past the barrier. We were interested in the fate of these fish and their contribution to the adult population. Bear Creek, on the other hand, has always had full access for anadromous cutthroat through much of its drainage. These two systems permit a comparison of life history characteristics, migration, and survival of coastal cutthroat rearing in streams above and below migration barriers, and provide study sites in Oregon to compliment research by USFWS of coastal cutthroat migration behavior in tributaries entering the estuary from the north side of the Columbia River (USFWS 2008; and see Hudson et al. 2008; Johnson 2008; Zydlewski et al. 2008). A major objective of our work in Big Creek and Bear Creek was to increase understanding of coastal cutthroat trout biology and the relationship between resident and migratory cutthroat in lower Columbia tributaries. Additionally, we sought to document habitat use in the Columbia River estuary by migrant cutthroat. Our specific objectives were to: • Estimate abundance of coastal cutthroat trout in Big Creek (above hatchery barrier) and Bear Creek (above and below a large dam) • Quantify the proportions of the cutthroat populations that are migratory, identify which individuals migrate and describe the timing of migration • Describe habitats used by anadromous migrants and characterize migration behavior within the Columbia River estuary • Measure estuarine/marine survival of anadromous individuals and document return to natal streams Close

• 119. [Article] Factors associated with dusky Canada goose nesting and nest success on artificial nest islands of the western Copper River Delta

  The population of dusky Canada geese (Branta canadensis occidentalis; hereafter, dusky geese) nesting on the western Copper River Delta (CRD) in south- central Alaska has been in decline since the late ...

  Citation × Citation Citation Abstract Copy Title: Factors associated with dusky Canada goose nesting and nest success on artificial nest islands of the western Copper River Delta Author: Maggiulli, Nicole Marie The population of dusky Canada geese (Branta canadensis occidentalis; hereafter, dusky geese) nesting on the western Copper River Delta (CRD) in south- central Alaska has been in decline since the late 1970s. In an effort to alleviate mammalian predation, increase nest success, and avoid a listing under the U.S. Endangered Species Act, an artificial nest island (island) program was implemented on the western CRD in 1983. The installation of new islands on the CRD is the sole management action of the Pacific Flyway Council on the breeding grounds, but no comprehensive evaluation of the program has been published. I examined general trends in island use and nest success over time for three island types (donut islands, fiberglass floater islands, and sandbag islands) from 1984-2005. I used data from the island program to identify factors associated with dusky Canada goose nesting (hereafter, use) and nest success on islands from 1996-2005. I generated a series of candidate models and used logistic regression with model selection techniques to determine how variables representing pond characteristics, vegetative characteristics, interactions with conspecifics and larid species, the previous year’s island status, and the distance to predator corridors were associated with island use and nest success for each year. Use of islands by dusky geese nesting on the western CRD increased between 1987 and 2005 from a low of 10% in 1987 to 44% in 2005. There was annual variability in factors associated with island use; however, use of islands was most consistently and strongly associated with the previous year’s island status. The odds of a nest being placed on an island that contained a successful nest the previous year were 2.91 to 6.62 times greater than for islands not used the previous year. There was also evidence for an increased likelihood of island use further from shore and for islands with up to 55% aerial shrub cover and shrubs up to 1 m tall. Nest success was consistently high, indicating islands have long term potential for increasing dusky goose nest success on the Copper River Delta. Compared to island use, my analysis of nest success and habitat features resulted in many more competitive models (average 10 v. 2 per year) with fewer strong (95% confidence intervals for parameter estimates excluded zero) associations between explanatory variables and nest success. Explanatory variables representing vegetative characteristics, interactions with conspecifics and larid species, and the distance to predator corridors had a relatively low capacity to explain nest success on artificial islands. However, there was some evidence for an increased likelihood of nest success on islands further from shore with shorter shrubs. Lower variability in factors associated with island use is likely because factors associated with nest site selection are controlled by decisions of the nesting goose. The importance of previous year’s island status on island use likely reflects high site fidelity by breeding adult geese, with fidelity being higher for birds that have successful nests. Alternately, dusky geese use cues from the previous year’s nesting activity when prospecting for island nest sites. In contrast, nest success is dependent on a more complex combination of factors that vary within and among years outside the control of a nesting goose. Inter-annual variation in the timing and magnitude of eulachon (Thaleichthys pacificus) spawning runs on large sloughs of the CRD and prey-switching by important dusky goose nest predators may have considerable influence on dusky goose nest success on islands, similar to mainland- nesting dusky geese. The inability to control for eulachon presence and abundance may have confounded my analysis of habitat features important to nest success. Therefore, factors such as presence of alternate prey (and predator abundance) may be more important to dusky goose nest success on islands than habitat features. Current use of available nest islands is at a program high of 44% and nest success also remains high (63%); suggesting the artificial nest island program is valuable for dusky geese. However, the contribution of island-nesting dusky geese to the dusky goose population on the Copper River Delta is unclear. There is a need for a population model that incorporates all recent information on dusky goose reproductive ecology to determine if artificial nest islands can increase dusky goose population size, and if so, how many islands are needed. Title: Factors associated with dusky Canada goose nesting and nest success on artificial nest islands of the western Copper River Delta Author: Maggiulli, Nicole Marie The population of dusky Canada geese (Branta canadensis occidentalis; hereafter, dusky geese) nesting on the western Copper River Delta (CRD) in south- central Alaska has been in decline since the late 1970s. In an effort to alleviate mammalian predation, increase nest success, and avoid a listing under the U.S. Endangered Species Act, an artificial nest island (island) program was implemented on the western CRD in 1983. The installation of new islands on the CRD is the sole management action of the Pacific Flyway Council on the breeding grounds, but no comprehensive evaluation of the program has been published. I examined general trends in island use and nest success over time for three island types (donut islands, fiberglass floater islands, and sandbag islands) from 1984-2005. I used data from the island program to identify factors associated with dusky Canada goose nesting (hereafter, use) and nest success on islands from 1996-2005. I generated a series of candidate models and used logistic regression with model selection techniques to determine how variables representing pond characteristics, vegetative characteristics, interactions with conspecifics and larid species, the previous year’s island status, and the distance to predator corridors were associated with island use and nest success for each year. Use of islands by dusky geese nesting on the western CRD increased between 1987 and 2005 from a low of 10% in 1987 to 44% in 2005. There was annual variability in factors associated with island use; however, use of islands was most consistently and strongly associated with the previous year’s island status. The odds of a nest being placed on an island that contained a successful nest the previous year were 2.91 to 6.62 times greater than for islands not used the previous year. There was also evidence for an increased likelihood of island use further from shore and for islands with up to 55% aerial shrub cover and shrubs up to 1 m tall. Nest success was consistently high, indicating islands have long term potential for increasing dusky goose nest success on the Copper River Delta. Compared to island use, my analysis of nest success and habitat features resulted in many more competitive models (average 10 v. 2 per year) with fewer strong (95% confidence intervals for parameter estimates excluded zero) associations between explanatory variables and nest success. Explanatory variables representing vegetative characteristics, interactions with conspecifics and larid species, and the distance to predator corridors had a relatively low capacity to explain nest success on artificial islands. However, there was some evidence for an increased likelihood of nest success on islands further from shore with shorter shrubs. Lower variability in factors associated with island use is likely because factors associated with nest site selection are controlled by decisions of the nesting goose. The importance of previous year’s island status on island use likely reflects high site fidelity by breeding adult geese, with fidelity being higher for birds that have successful nests. Alternately, dusky geese use cues from the previous year’s nesting activity when prospecting for island nest sites. In contrast, nest success is dependent on a more complex combination of factors that vary within and among years outside the control of a nesting goose. Inter-annual variation in the timing and magnitude of eulachon (Thaleichthys pacificus) spawning runs on large sloughs of the CRD and prey-switching by important dusky goose nest predators may have considerable influence on dusky goose nest success on islands, similar to mainland- nesting dusky geese. The inability to control for eulachon presence and abundance may have confounded my analysis of habitat features important to nest success. Therefore, factors such as presence of alternate prey (and predator abundance) may be more important to dusky goose nest success on islands than habitat features. Current use of available nest islands is at a program high of 44% and nest success also remains high (63%); suggesting the artificial nest island program is valuable for dusky geese. However, the contribution of island-nesting dusky geese to the dusky goose population on the Copper River Delta is unclear. There is a need for a population model that incorporates all recent information on dusky goose reproductive ecology to determine if artificial nest islands can increase dusky goose population size, and if so, how many islands are needed. Close