Apparent predation of juvenile coho salmon (Oncorhynchus kisutch) by prickly sculpins (Cottus asper) is an artefact of trapping methodology

2006 ◽  
Vol 57 (5) ◽  
pp. 513 ◽  
Author(s):  
Londi M. Tomaro
Keyword(s):  
Coho Salmon ◽  
Oncorhynchus Kisutch ◽  
Stomach Contents ◽  
Early Life History ◽  
Boreal Summer ◽  
Life Stages ◽  
Life History Stages ◽  
Juvenile Salmonids ◽  
Freshwater Sculpin ◽  
Trap Bias

Freshwater sculpins often inhabit the same waterways as juvenile salmonids and may impact the survival of juvenile salmonids through predation on early life-history stages. In the present study, the stomach contents of 2302 individual Cottus asper, a freshwater sculpin, collected from Auke Lake, Alaska, were examined during the boreal summer of 2000 to determine if C. asper are important natural predators of juvenile coho salmon (Oncorhynchus kisutch), and to explore possible trap bias of gear used in preliminary diet studies. The diet of sculpins collected in confining traps was compared with the diet of sculpins collected in nets. Significant predation on pre-smolt coho salmon by trapped sculpins, but none by netted sculpins, was observed. This result provides strong evidence of trap bias in the observed diet of C. asper. The remainder of the diet of trapped sculpins also differed significantly from that of netted sculpins. Significantly more trapped sculpins had eaten plant material and fish, whereas significantly more netted sculpins had consumed molluscs. Finally, sculpin diet was correlated with sculpin size, which may influence predation on other salmonid life-stages. These results expand our understanding of prickly sculpin diet and show that they are not important predators of juvenile coho salmon. These findings also demonstrate the importance of assessing the potential bias of collection gear and sampling techniques.

scholarly journals Seeds and Seedlings in a Changing World: A Systematic Review and Meta-Analysis from High Altitude and High Latitude Ecosystems

Plants ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 768
Author(s):  
Jerónimo Vázquez-Ramírez ◽  
Susanna E. Venn
Keyword(s):  
Climate Change ◽  
High Altitude ◽  
High Latitude ◽  
Seedling Establishment ◽  
Early Life History ◽  
Life Stages ◽  
Qualitative And Quantitative Analysis ◽  
Qualitative And Quantitative ◽  
Life History Stages ◽  
Early Snowmelt

The early life-history stages of plants, such as germination and seedling establishment, depend on favorable environmental conditions. Changes in the environment at high altitude and high latitude regions, as a consequence of climate change, will significantly affect these life stages and may have profound effects on species recruitment and survival. Here, we synthesize the current knowledge of climate change effects on treeline, tundra, and alpine plants’ early life-history stages. We systematically searched the available literature on this subject up until February 2020 and recovered 835 potential articles that matched our search terms. From these, we found 39 studies that matched our selection criteria. We characterized the studies within our review and performed a qualitative and quantitative analysis of the extracted meta-data regarding the climatic effects likely to change in these regions, including projected warming, early snowmelt, changes in precipitation, nutrient availability and their effects on seed maturation, seed dormancy, germination, seedling emergence and seedling establishment. Although the studies showed high variability in their methods and studied species, the qualitative and quantitative analysis of the extracted data allowed us to detect existing patterns and knowledge gaps. For example, warming temperatures seemed to favor all studied life stages except seedling establishment, a decrease in precipitation had a strong negative effect on seed stages and, surprisingly, early snowmelt had a neutral effect on seed dormancy and germination but a positive effect on seedling establishment. For some of the studied life stages, data within the literature were too limited to identify a precise effect. There is still a need for investigations that increase our understanding of the climate change impacts on high altitude and high latitude plants’ reproductive processes, as this is crucial for plant conservation and evidence-based management of these environments. Finally, we make recommendations for further research based on the identified knowledge gaps.

Predation by River Otters (Lutra canadensis) on Juvenile Coho Salmon (Oncorhynchus kisutch) and Dolly Varden (Salvelinus malma) in Southeast Alaska

1993 ◽  
Vol 50 (2) ◽  
pp. 312-315 ◽  
Author(s):  
C. Andrew Dolloff
Keyword(s):  
Coho Salmon ◽  
Oncorhynchus Kisutch ◽  
River System ◽  
Dolly Varden ◽  
Salvelinus Malma ◽  
Southeast Alaska ◽  
River Otters ◽  
Juvenile Salmonids ◽  
Dolly Varden Salvelinus Malma ◽  
Lutra Canadensis

The effect of predation by river otters (Lutra canadensis) on juvenile coho salmon (Oncorhynchus kisutch) and Dolly Varden (Salvelinus malma) in a Southeast Alaska watershed was inferred by examining the number and size distribution of sagittal otoliths that were found in otter scats. Individual scats contained up to 408 otoliths, indicating that at least 200 fish had been eaten between defecations. Otoliths from juvenile salmonids outnumbered those from coastrange sculpins (Cottus aleuticus) by about six to one. Based on examination of over 8000 otoliths found in otter scats, at least 3300 juvenile salmonids were eaten by two river otters and their two young in the Kadashan River system during a 6-wk period in late spring 1985.

Fecundity of Coho Salmon (Oncorhynchus kisutch) from the Great Lakes and a Comparison with Ocean Salmon

1976 ◽  
Vol 33 (5) ◽  
pp. 1150-1155 ◽  
Author(s):  
Thomas M. Stauffer
Keyword(s):  
Great Lakes ◽  
Early Life ◽  
First Generation ◽  
Lake Michigan ◽  
Coho Salmon ◽  
Pacific Salmon ◽  
Lake Superior ◽  
Oncorhynchus Kisutch ◽  
Early Life History ◽  
Freshwater Salmon

I measured fecundity of coho salmon (Oncorhynchus kisutch) that matured in the Great Lakes to make comparisons with Pacific Ocean coho salmon and among groups of Great Lakes salmon. Numbers of eggs produced (1600–3500) by Great Lakes salmon were comparable to production (1500–3300) by Pacific salmon of similar size. Average egg diameters of Lake Michigan (7.1–7.4 mm) and Pacific salmon (6.1–7.4 mm) were also comparable but Lake Superior eggs were smaller (5.1–5.4 mm). Fecundity of second generation freshwater salmon which originated from Lake Michigan eggs was similar to that of the first generation which originated from Pacific eggs because the average numbers (2938–3243) and diameters (7.1–7.4 mm) of eggs produced were about the same. On the average, Lake Michigan salmon contained more (2938) and larger (7.1-mm diam) eggs than did Lake Superior salmon (2150 and 5.1-mm diam) of the same year-class and early life history.

Two generations of outbreeding in coho salmon (Oncorhynchus kisutch): effects on size and growth

2005 ◽  
Vol 62 (11) ◽  
pp. 2538-2547 ◽  
Author(s):  
Erin K McClelland ◽  
James M Myers ◽  
Jeffrey J Hard ◽  
Linda K Park ◽  
Kerry A Naish
Keyword(s):  
Growth Rates ◽  
Coho Salmon ◽  
Pacific Salmon ◽  
Oncorhynchus Kisutch ◽  
Late Summer ◽  
Early Life History ◽  
Lower Growth ◽  
Freshwater Aquaculture ◽  
In Captivity ◽  
Two Generations

Outbreeding is a potential genetic risk in Pacific salmon (Oncorhynchus spp.) when aquaculture practices introduce nonnative domesticated fish to wild environments, making interbreeding with wild populations possible. In this study, F1 and F2 hybrid families of coho salmon (Oncorhynchus kisutch) were created using a captive freshwater aquaculture strain and a locally derived hatchery population that is integrated with naturally spawning fish. Intermediate growth was detected in F1 and F2 hybrids from crosses reared in captivity; both generations had mean weight and length values between those of the parent populations after their first year (p < 0.05). In the early life history stages, maternal effects increased alevin growth in progeny of hatchery dams relative to those of captive dams (p < 0.001). Aquaculture control families showed greater growth rates than hybrids in late summer of their 1st year and in the following spring (p < 0.05), while the hatchery controls had lower growth rates during the first summer (p < 0.05). Line cross analysis indicated that changes in additive and dominance interactions, but not unfavorable epistatic interactions, likely explain the differences in weight, length, and growth rate observed in hybrids of these stocks of coho salmon.

Stomach Flushing: Effectiveness and Influence on Survival and Condition of Juvenile Salmonids

1978 ◽  
Vol 35 (10) ◽  
pp. 1359-1363 ◽  
Author(s):  
William R. Meehan ◽  
Richard A. Miller
Keyword(s):  
Coho Salmon ◽  
Feeding Habits ◽  
Stomach Contents ◽  
Cutthroat Trout ◽  
Wild Fish ◽  
Key Words Stomach ◽  
Hatchery Fish ◽  
Juvenile Salmonids ◽  
Significant Difference ◽  
Change In Mean

Hydraulic stomach flushing was an effective method to analyze relative food consumption and feeding habits of young salmonids. Coho salmon (Oncorhynchus kisutch) stomachs were most effectively flushed — 99% of invertebrate organisms (96% of weight of stomach contents); 92% of organisms (83% of weight) were flushed from cutthroat trout (Salmo clarki) stomachs, 90% of organisms (77% of weight) were flushed from rainbow trout (S. gairdneri) stomachs. Stomach flushing did not affect survival of juvenile coho salmon. A significant difference in change in mean condition factor between wild and hatchery fish was found after 30 d (greater change in wild fish), and a significant change was observed between the mean condition factors of control and treated hatchery fish. No difference was found between control and treated wild fish. Key words: stomach flushing, juvenile salmonids, survival, condition, food habits

Detection of population trends in threatened coho salmon (Oncorhynchus kisutch)

2001 ◽  
Vol 58 (2) ◽  
pp. 375-385 ◽  
Author(s):  
Katriona Shea ◽  
Marc Mangel
Keyword(s):  
Life History ◽  
Statistical Power ◽  
Coho Salmon ◽  
Oncorhynchus Kisutch ◽  
Life History Stage ◽  
Vital Rates ◽  
Life History Stages ◽  
Observational Uncertainty ◽  
Two Parameters ◽  
Management Recommendations

Populations of coho salmon (Oncorhynchus kisutch) in California are listed as threatened under the U.S. Endangered Species Act. Such listings refer to adult populations, but often, juvenile life history stages are censused, so it is important to understand what affects the relationship between true adult and observed juvenile numbers. We present models to address how observational uncertainty, census length, and autocorrelation in vital rates affect our ability to observe trends. We ask two questions about our ability to detect declines in one life history stage from censuses of another. First, given an observed decline in parr numbers, what is the chance that this reflects a decline in adults? Second, given that adult numbers are declining, what is the chance that we see that decline in parr? Our results indicate that statistical power decreases with increasing observational uncertainty and decreasing census lengths and demonstrate how these two parameters interact. Power increases as the level of autocorrelation in mortality rates increases. Management recommendations include obtaining more accurate estimates of autocorrelation in mortality and of observational uncertainty.

Response of juvenile coho salmon (Oncorhynchus kisutch) and steelhead (Oncorhynchus mykiss) to the addition of salmon carcasses to two streams in southwestern Washington, U.S.A.

1998 ◽  
Vol 55 (8) ◽  
pp. 1909-1918 ◽  
Author(s):  
Robert E Bilby ◽  
Brian R Fransen ◽  
Peter A Bisson ◽  
Jason K Walter
Keyword(s):  
Oncorhynchus Mykiss ◽  
Coho Salmon ◽  
Isotope Analysis ◽  
Oncorhynchus Kisutch ◽  
Stomach Contents ◽  
Similar Increase ◽  
Reference Sites ◽  
Food Items ◽  
Small Streams ◽  
Salmon Carcasses

Availability of organic matter and nutrients transported from the marine environment to streams by spawning salmon was increased in two small streams in southwestern Washington, U.S.A., by adding salmon carcasses from a nearby hatchery. Response of juvenile coho salmon (Oncorhynchus kisutch) and steelhead (Oncorhynchus mykiss) rearing at these sites was compared with nearby streams where few salmon spawned. Densities of age 0+ coho salmon and age 0+ and age 1+ steelhead increased following carcass additions to the treated streams. A similar increase in density was not observed at the reference sites. Condition factors in treated streams increased following carcass addition and remained at high levels while carcasses were present whereas no similar pattern was observed at the reference sites. Stomach contents of fish in streams to which carcasses had been added consisted primarily of salmon eggs and carcass flesh when carcasses were present in the stream. Stable isotope analysis indicated that the proportion of marine-derived nitrogen in the muscle tissue of juvenile salmonids increased as much as 39% following carcass placement. Results suggest that eggs and carcasses of adult salmon provide a very important resource during a period when other food items are often scarce.

scholarly journals Quantitative molecular detection of larval Atlantic herring (Clupea harengus) in stomach contents of Atlantic mackerel (Scomber scombrus) marks regions of predation pressure

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Bridie Jean Marie Allan ◽  
Jessica Louise Ray ◽  
Maik Tiedemann ◽  
Valeriya Komyakova ◽  
Frode Vikebø ◽  
...  
Keyword(s):  
Early Life ◽  
Molecular Detection ◽  
Stomach Contents ◽  
Early Life History ◽  
Predation Pressure ◽  
Clupea Harengus ◽  
Atlantic Herring ◽  
Atlantic Mackerel ◽  
Life History Stages ◽  
Scomber Scombrus

AbstractMortality rates in the early life-history stages of fishes are generally high yet identifying the causes remain unclear. Faltering recruitment rates of Atlantic herring (Clupea harengus) in the Norwegian Sea indicate a need to identify which mortality factors influence larval herring survival. Previous research suggests that increased predation pressure by Atlantic mackerel (Scomber scombrus) may contribute to the disconnect between spawning stock biomass and recruitment. To quantify the contribution of predation pressure by Atlantic mackerel to herring larval mortality, two research cruises were conducted within a probable “hot spot” (67–72° N) for intensified mackerel predation based on particle drift simulations. Mackerel stomach contents were analysed for herring larvae content using droplet digital polymerase chain reaction (ddPCR) with a quantitative molecular detection assay specific for herring. The ddPCR results demonstrate clear predation by mackerel on herring larvae and also suggest that the alternative use of visual examination may give misleading results. Our results show that mackerel should be considered a potentially important predator on herring larvae. The quantitative molecular assay presented here shows great promise as an efficient and specific tool to correctly identify and quantify predation pressure on early life-history stages of fishes.

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