scholarly journals California Current seascape influences juvenile salmon foraging ecology at multiple scales

2020 ◽  
Vol 634 ◽  
pp. 159-173 ◽  
Author(s):  
MC Sabal ◽  
EL Hazen ◽  
SJ Bograd ◽  
RB MacFarlane ◽  
ID Schroeder ◽  
...  
Keyword(s):  
Multiple Scales ◽  
Foraging Ecology ◽  
California Current ◽  
Juvenile Salmon

Condition-dependent foraging strategies in a coastal seabird: evidence for the rich get richer hypothesis

2018 ◽  
Vol 30 (2) ◽  
pp. 356-363 ◽  
Author(s):  
Brock Geary ◽  
Scott T Walter ◽  
Paul L Leberg ◽  
Jordan Karubian
Keyword(s):  
Individual Variation ◽  
Multiple Scales ◽  
Foraging Ecology ◽  
Population Level ◽  
Foraging Strategies ◽  
Significant Relationships ◽  
Fitness Consequences ◽  
Brown Pelicans ◽  
The Rich ◽  
Foraging Movements

Abstract The degree to which foraging individuals are able to appropriately modify their behaviors in response to dynamic environmental conditions and associated resource availability can have important fitness consequences. Despite an increasingly refined understanding of differences in foraging behavior between individuals, we still lack detailed characterizations of within-individual variation over space and time, and what factors may drive this variability. From 2014 to 2017, we used GPS transmitters and accelerometers to document foraging movements by breeding adult Brown Pelicans (Pelecanus occidentalis) in the northern Gulf of Mexico, where the prey landscape is patchy and dynamic at various scales. Assessments of traditional foraging metrics such as trip distance, linearity, or duration did not yield significant relationships between individuals. However, we did observe lower site fidelity and less variation in energy expenditure in birds of higher body condition, despite a population-level trend of increased fidelity as the breeding season progressed. These findings suggest that high-quality individuals are both more variable and more efficient in their foraging behaviors during a period of high energetic demand, consistent with a “rich get richer” scenario in which individuals in better condition are able to invest in more costly behaviors that provide higher returns. This work highlights the importance of considering behavioral variation at multiple scales, with particular reference to within-individual variation, to improve our understanding of foraging ecology in wild populations.

Reconstructing habitat use by juvenile salmon sharks links upwelling to strandings in the California Current

2015 ◽  
Vol 525 ◽  
pp. 217-228 ◽  
Author(s):  
AB Carlisle ◽  
SY Litvin ◽  
EL Hazen ◽  
DJ Madigan ◽  
KJ Goldman ◽  
...  
Keyword(s):  
Habitat Use ◽  
California Current ◽  
Juvenile Salmon

The Ecology of Juvenile Salmon in the Northeast Pacific Ocean: Regional Comparisons

2007 ◽  
Keyword(s):  
Fish Assemblages ◽  
Pacific Salmon ◽  
California Current ◽  
Minor Component ◽  
Species Group ◽  
Juvenile Salmon ◽  
Species Assemblages ◽  
Coastal Species ◽  
Night And Day ◽  
Associated Species

Abstract.—We compared epipelagic fish assemblages associated with juvenile (ocean-age 0) Pacific salmon <em>Oncorhynchus </em>spp. from neritic waters of the California Current and Alaska Current regions in the spring–summer and summer–fall periods of 2000–2004. Catches originated from rope trawl surveys conducted between latitudes 37°N and 60°N and spanned more than 1,100 km in the coastal and inshore habitats of each region. Catch data were used from the epipelagic sampling of waters from near surface to depths of about 18 m, primarily over the continental shelf. Catch composition, frequency of occurrence, and density were evaluated between regions and habitats for day sampling. Diel (night and day) catch comparisons were also made at a few localities in each region. In day catches from both regions, a total of 1.69 million fish and squid representing 52 fish families and 118 fish species were sampled from 2,390 trawl hauls. Ninety-seven percent of the daytime catch was composed of 11 fish families and squid in coastal and inshore habitats of each region: clupeids dominated catches in the California Current (72% and 76% of catch, respectively), and salmonids dominated catches in the Alaska Current (46% and 62% of catch, respectively). Juveniles comprised 81–99% of salmon sampled in both coastal and inshore habitats of each region. Frequencies of occurrence were highest for juvenile salmon in both regions, but average densities were highest for Pacific herring <em>Clupea pallasii </em>and Pacific sardine <em>Sardinops sagax </em>in the California Current region. Cluster analyses revealed distinct geographic breakpoints in coastal species assemblages off central Vancouver Island and in inshore species assemblages in southeastern Alaska. Species were found to cluster into six groups from coastal localities and four groups from inshore localities. Indicator species analysis and nonmetric multidimensional scaling revealed that most species of juvenile salmonids were located in northern localities. Although juvenile salmon had the most uniform distribution of any species group, their densities relative to associated species were dramatically lower in the California Current, suggesting a higher degree of interactions between juvenile salmon and other species in this region. Diel comparisons in both regions indicated substantially higher catches at night, particularly of clupeids, osmerids, and gadids. Salmonids were a relatively minor component of the night catch in both regions due to dramatic diel shifts in community structure. Additional study of diel interactions of juvenile salmon and associated species is needed to quantify habitat utilization dynamics in marine ecosystems.

Foraging ecology and movement patterns of jumbo squid (Dosidicus gigas) in the California Current System

2013 ◽  
Vol 95 ◽  
pp. 37-51 ◽  
Author(s):  
John C. Field ◽  
Carl Elliger ◽  
Ken Baltz ◽  
Graham E. Gillespie ◽  
William F. Gilly ◽  
...  
Keyword(s):  
Foraging Ecology ◽  
Current System ◽  
California Current ◽  
Movement Patterns ◽  
Dosidicus Gigas ◽  
California Current System ◽  
Jumbo Squid

A multivariate stock–recruitment function for cohorts with sympatric subclasses: application to maternal effects in rockfish (genus Sebastes)

2009 ◽  
Vol 66 (4) ◽  
pp. 557-564 ◽  
Author(s):  
Yasmin Lucero
Keyword(s):  
Maternal Effects ◽  
California Current ◽  
Mortality Rates ◽  
Life History Strategies ◽  
Juvenile Salmon ◽  
Black Rockfish ◽  
Older Mothers ◽  
Stock Recruitment ◽  
Flexible Framework ◽  
Sebastes Melanops

I present a multivariate stock–recruitment function (MSRF) for calculating recruitment when a cohort comprises sympatric subclasses. Sympatric subclasses emerge when there are closely interacting subgroups occupying a very similar niche, but whose ecology dictates distinct mortality rates. Examples include multispecies complexes of juvenile rockfish ( Sebastes spp.) in the California current and juvenile salmon ( Oncorhynchus spp.) in streams following different life history strategies. I derive an MSRF and apply it to the ecology of larval and juvenile rockfish with maternal effects. In several species of rockfish, older mothers produce superior larvae. This is called a maternal effect. For these species, larval and juvenile cohorts comprise several sympatric subclasses, each with a distinct mortality rate related to the age of their mothers. I apply this model to data for black rockfish ( Sebastes melanops ) in California and Oregon and find the recruitment estimates based on data from a declining population may overestimate productivity of a recovering population if maternal effects are neglected. The MSRF proves to be a flexible framework for studying recruitment in the presence of sympatric subclasses.

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