Egg consumption in mature Pacific salmon (Oncorhynchus spp.)

2009 ◽  
Vol 66 (9) ◽  
pp. 1546-1553 ◽  
Author(s):  
Shawn R. Garner ◽  
John W. Heath ◽  
Bryan D. Neff
Keyword(s):  
Pacific Salmon ◽  
Feeding Rates ◽  
Spawning Habitat ◽  
Local Adaptations ◽  
Egg Consumption ◽  
Feeding Experiments ◽  
Migration Corridors ◽  
And Migration ◽  
Multiple Species ◽  
Fundamental Shift

For over a century, conventional wisdom has maintained that Pacific salmon ( Oncorhynchus spp.) cease feeding when they return to freshwater rivers to spawn. Here, we overturn this belief by showing that multiple species of Pacific salmon consume eggs during spawning. Overall, 13% of stomachs contained eggs, and feeding rates were estimated at up to 14 eggs or 52 kJ per day. Feeding experiments revealed that mature salmon could digest eggs, as fed salmon maintained significantly higher body mass than unfed salmon. Such egg consumption presents a fundamental shift in our understanding of Pacific salmon ecology that may have important implications for migration and management models. Indeed, the energy from consumed eggs could allow salmon to migrate up to an additional 3.8 km upstream per day of feeding, or extend the duration of spawning activity by up to 12%. Furthermore, salmon stocks may have evolved local adaptations to their specific migration and spawning requirements that include nutrients from salmon eggs. Thus, successful salmon management efforts may need to preserve not only spawning habitat and migration corridors, but also feeding opportunities.

Differential effects of turbidity on prey consumption of piscivorous and planktivorous fish

2003 ◽  
Vol 60 (12) ◽  
pp. 1517-1526 ◽  
Author(s):  
Alex De Robertis ◽  
Clifford H Ryer ◽  
Adriana Veloza ◽  
Richard D Brodeur
Keyword(s):  
Light Intensity ◽  
Prey Capture ◽  
High Light Intensity ◽  
Prey Consumption ◽  
Planktivorous Fish ◽  
Oncorhynchus Keta ◽  
Feeding Rates ◽  
Anoplopoma Fimbria ◽  
Piscivorous Fish ◽  
Feeding Experiments

Contrast degradation theory predicts that increased turbidity decreases the visibility of objects that are visible at longer distances more than that of objects that are visible at short distances. Consequently, turbidity should disproportionately decrease feeding rates by piscivorous fish, which feed on larger and more visible prey than particle-feeding planktivorous fish. We tested this prediction in a series of laboratory feeding experiments, the results of which indicated that prey consumption by two species of planktivorous fish (juvenile chum salmon (Oncorhynchus keta) and walleye pollock (Theragra chalcogramma)) is much less sensitive to elevated turbidity than piscivorous feeding by sablefish (Anoplopoma fimbria). Planktivorous feeding in the turbidity range tested (0–40 nephelometric turbidity units (NTU)) was reduced at high light intensity, but not at low light intensity. Comparatively low (5–10 NTU) turbidity decreased both the rate at which sablefish pursued prey and the probability of successful prey capture. These results suggest that turbid environments may be advantageous for planktivorous fish because they will be less vulnerable to predation by piscivores, but will not experience a substantial decrease in their ability to capture zooplankton prey.

Gene Differentiation in Pacific Salmon (Oncorhynchus sp.): Facts and Models with Reference to Pink Salmon (O. gorbuscha)

1994 ◽  
Vol 51 (S1) ◽  
pp. 223-232 ◽  
Author(s):  
Lev A. Zhivotovsky ◽  
A. J. Gharrett ◽  
A. J. McGregor ◽  
M. K. Glubokovsky ◽  
Marcus W. Feldman
Keyword(s):  
Pacific Salmon ◽  
Gene Diversity ◽  
Genetic Relationships ◽  
Pink Salmon ◽  
Theoretical Models ◽  
Genetic Distances ◽  
Gene Drift ◽  
Gene Differentiation ◽  
Or Gene ◽  
And Migration

Analyzing population genetic data usually involves examining relationships among populations followed by analysis of the distribution of genetic variability. Genetic relationships are often depicted with multidimensional scaling or trees constructed from genetic distances; genetic variation within and among populations is partitioned using gene diversity measures such as FST or GST. Genetic distances or gene diversity are often used to estimate influences of gene drift, migration, and/or selection on observed gene differentiation. We used allozyme data for pink salmon populations to examine the theoretical models available for estimating magnitudes of these factors in Pacific salmon populations. The models included (1) mutation and gene drift; (2) mutation and migration; (3) migration and gene drift; and (4) gene drift, migration, and selection. These models suggest that gene drift and migration are probably important at the lowest levels of population hierarchy, but even very small forces such as weak heterogeneous selection and low migration levels may be important at higher levels. The accuracy of some estimates should be questioned because for many situations appropriate models are either not yet available or are not sufficiently refined. Also, the dynamic genetic structure of salmon populations makes it unlikely that the steady state assumed for many theoretical models has obtained.

Major stopover regions and migratory bottlenecks for Nearctic-Neotropical landbirds within the Neotropics: a review

2017 ◽  
Vol 28 (1) ◽  
pp. 1-26 ◽  
Author(s):  
NICHOLAS J. BAYLY ◽  
KENNETH V. ROSENBERG ◽  
WENDY E. EASTON ◽  
CAMILA GÓMEZ ◽  
JAY CARLISLE ◽  
...  
Keyword(s):  
Sierra Nevada ◽  
Migratory Birds ◽  
Current Knowledge ◽  
Boreal Winter ◽  
Long Distance ◽  
Important Distinction ◽  
Conservation Actions ◽  
Neotropical Migratory Birds ◽  
And Migration ◽  
Multiple Species

SummaryNearly 300 species of landbirds, whose populations total billions, migrate between the Neotropics and North America. Many migratory populations are in steep decline, and migration is often identified as the greatest source of annual mortality. Identifying birds’ needs on migration is therefore central to designing conservation actions for Nearctic-Neotropical migratory birds; yet migration through the Neotropics is a significant knowledge gap in our understanding of the full annual cycle. Here, we synthesise current knowledge of Neotropical stopover regions and migratory bottlenecks, focusing on long-distance, migratory landbirds that spend the boreal winter in South America. We make the important distinction between “true” stopover—involving multi-day refuelling stops—and rest-roost stops lasting < 24 hours, citing a growing number of studies that show individual landbirds making long stopovers in just a few strategic areas, to accumulate large energy reserves for long-distance flights. Based on an exhaustive literature search, we found few published stopover studies from the Neotropics, but combined with recent tracking studies, they describe prolonged stopovers for multiple species in the Orinoco grasslands (Llanos), the Sierra Nevada de Santa Marta (Colombia), and the Yucatan Peninsula. Bottlenecks for diurnal migrants are well described, with the narrowing Central American geography concentrating millions of migrating raptors at several points in SE Mexico, Costa Rica, Panama and the Darién. However, diurnally migrating aerial insectivores remain understudied, and determining stopover/roost sites for this steeply declining group is a priority. Despite advances in our knowledge of migration in the Neotropics, we conclude that major knowledge gaps persist. To identify stopover sites and habitats and the threats they face, we propose a targeted and collaborative research agenda at an expanded network of Neotropical sites, within the context of regional conservation planning strategies.

Model for Examining Early Ocean Limitation of Pacific Salmon Production

1978 ◽  
Vol 35 (10) ◽  
pp. 1303-1315 ◽  
Author(s):  
Carl J. Walters ◽  
Ray Hilborn ◽  
Randall M. Peterman ◽  
Michael J. Staley
Keyword(s):  
Body Size ◽  
Simulation Model ◽  
Marine Biology ◽  
Pacific Salmon ◽  
Juvenile Fish ◽  
Computer Simulation Model ◽  
Population Limitation ◽  
Near Surface ◽  
And Migration ◽  
Zooplankton Production

A computer simulation model was used to examine growth and survival of all major British Columbia salmon stocks during their first 6 mo of ocean life. Factors included in the calculations were the space–time distribution of zooplankton production, timing of salmon ocean arrival and migration especially as regards overlaps between stocks, feeding and growth in relation to food availability, and mortality rates in relation to body size. It is concluded that ocean limitation of production is unlikely unless only a small fraction of total zooplankton production is available to the salmon. The model emphasizes several critical uncertainties about the marine biology of salmon: rates of replenishment of near surface zooplankton stocks (where most salmon feeding occurs) from deeper water have not been adequately measured, and the functional response of salmon to prey density is not understood. There is inadequate data on the relationship between body size and mortality rate, and migration patterns of juvenile fish have not been documented precisely enough. Hopefully some of these uncertainties will be resolved through the salmon enhancement programs. Key words: salmon, population limitation, juvenile marine production, simulation model

Comment on “Egg consumption in mature Pacific salmon (Oncorhynchus spp.)”Appears in Can. J. Fish. Aquat. Sci. 66(9): 1546–1553.

2010 ◽  
Vol 67 (12) ◽  
pp. 2052-2054 ◽  
Author(s):  
Jonathan B. Armstrong
Keyword(s):  
Recent Article ◽  
Chum Salmon ◽  
Pacific Salmon ◽  
Stomach Contents ◽  
Energy Budgets ◽  
Egg Consumption ◽  
Salmon Eggs ◽  
Consumption Rates

In their recent article, “Egg consumption in mature Pacific salmon ( Oncorhynchus spp.)” (Can. J. Fish. Aquat. Sci. 66(9): 1546–1553), Garner et al. observed salmon eggs in the stomach contents of mature Chinook, coho, and chum salmon. Through experimentation and simulation of salmon energetics, the authors conclude that the observed feeding represents an important gain in energy, challenging the accepted paradigm that assumes salmon energy budgets contain no gains once adults return to freshwater. Here, I argue that Garner et al. have overestimated the energetic consequence of egg consumption and that the observed consumption rates do not represent biologically significant gains in energy.

scholarly journals Indirect versus Direct Effects of Freshwater Browning on Larval Fish Foraging

2019 ◽  
Author(s):  
Dina M. Leech ◽  
Troy L. Clift ◽  
Jessica L. Littlefield ◽  
Nicholas R. Ravagli ◽  
Jacob E. Spain
Keyword(s):  
Largemouth Bass ◽  
Indirect Effects ◽  
Prey Availability ◽  
Larval Fish ◽  
Light Availability ◽  
Direct Effects ◽  
Feeding Rates ◽  
Growth And Survival ◽  
Feeding Experiments ◽  
Fish Spawning

ABSTRACTFish foraging and energy flow are both predicted to decline with freshwater ‘browning’ due to reductions in light availability. Studies investigating these predictions have focused on juveniles and adults; however, the larval stage represents a ‘critical period’ in fish development. We investigated the indirect versus direct effects of browning on zooplankton-larval fish interactions by altering water color with SuperHume (absorbance at 440 nm = 1.6 – 10.8 m−1). Phytoplankton and zooplankton densities were monitored across experimental tanks in the laboratory for one month leading up to fish spawning. Larval largemouth bass were then introduced to assess indirect effects on fish feeding rates and growth. Direct effects on foraging of largemouth bass and bluegill were determined with separate short-term feeding experiments. Browning did not directly alter the ability of larval fish to capture prey. However, significant indirect effects on larval fish foraging, growth, and survival were observed as phytoplankton and zooplankton decreased with increased browning. Our data suggest lake browning will reduce energy transfer to larval fish due to a reduction in prey availability but not visual foraging.

scholarly journals Big cats are still walking in El Salvador: first photographic records of Puma concolor (Linnaeus, 1771) and an overview of historical records in the country

Check List ◽  
2020 ◽  
Vol 16 (3) ◽  
pp. 563-570
Author(s):  
Andrea Morales-Rivas ◽  
Francisco S. Álvarez ◽  
Xochilt Pocasangre-Orellana ◽  
Luis Girón ◽  
Gloria N. Guerra ◽  
...  
Keyword(s):  
El Salvador ◽  
National Park ◽  
Puma Concolor ◽  
Conservation Strategy ◽  
Public Acceptance ◽  
Historical Records ◽  
Migration Corridors ◽  
And Migration ◽  
Wildlife Cameras ◽  
Photographic Records

The presence of Puma, Puma concolor, has been controversial in El Salvador due to the lack of published, verifiable data. We surveyed 119 sites in Montecristo National Park and 17 sites in the R&iacute;o Sapo basin using wildlife cameras. We detected Pumas in both areas, representing the first photographic records for El Salvador. We call for a national Puma conservation strategy with research in basic ecology and migration corridors, regulation of hunting, management of livestock losses, and public acceptance programs. The R&iacute;o Sapo basin should be granted formal protection.

scholarly journals Strontium isotopes delineate fine-scale natal origins and migration histories of Pacific salmon

2015 ◽  
Vol 1 (4) ◽  
pp. e1400124 ◽  
Author(s):  
Sean R. Brennan ◽  
Christian E. Zimmerman ◽  
Diego P. Fernandez ◽  
Thure E. Cerling ◽  
Megan V. McPhee ◽  
...  
Keyword(s):  
Life Histories ◽  
Pacific Salmon ◽  
Spatial Scales ◽  
Strontium Isotopes ◽  
Fine Scale ◽  
Complex Population ◽  
Population Structures ◽  
Relative Production ◽  
Provenance Research ◽  
And Migration

Highly migratory organisms present major challenges to conservation efforts. This is especially true for exploited anadromous fish species, which exhibit long-range dispersals from natal sites, complex population structures, and extensive mixing of distinct populations during exploitation. By tracing the migratory histories of individual Chinook salmon caught in fisheries using strontium isotopes, we determined the relative production of natal habitats at fine spatial scales and different life histories. Although strontium isotopes have been widely used in provenance research, we present a new robust framework to simultaneously assess natal sources and migrations of individuals within fishery harvests through time. Our results pave the way for investigating how fine-scale habitat production and life histories of salmon respond to perturbations—providing crucial insights for conservation.

Sign in / Sign up

Export Citation Format

Share Document