Post-settlement abundance, condition, and survival in a climate-stressed population of Pacific cod

2021 ◽  
Author(s):  
Alisa A. Abookire ◽  
Michael A. Litzow ◽  
Michael J. Malick ◽  
Benjamin Jeffrey Laurel
Keyword(s):  
Survival Data ◽  
Gulf Of Alaska ◽  
Early Summer ◽  
Pacific Cod ◽  
Larval Phase ◽  
Growth And Survival ◽  
Positive Effects ◽  
Juvenile Abundance ◽  
Spring Temperatures ◽  
Overwintering Survival

The Pacific cod (Gadus macrocephalus) fishery recently collapsed in the Gulf of Alaska after a series of marine heatwaves that began in 2014. To gauge the likelihood of population recovery following these extreme warming events, we investigate potential thermal stress on age-0 cohorts through a comprehensive analysis of juvenile cod abundance, condition, growth, and survival data collected from 15 years of beach seine surveys. Abundance was strongly negatively related to ocean temperature during the egg and larval phase (winter/spring), but age-0 cod were larger in the early summer following warm winter/spring temperatures. Body condition indices suggest that warm summers may improve energetic reserves prior to the first winter; however, there was no summer temperature effect on post-settlement growth or survival. Spatial differences in abundance, condition, or growth were not detected, and density-dependent effects were either weak or positive. While the positive effects of increased summer temperatures on juvenile condition may benefit overwintering survival, they cannot compensate for high pre-settlement mortality from warming winter/spring temperatures. We conclude the critical thermal bottleneck for juvenile abundance occurs pre-settlement.

scholarly journals Eighty years of food-web response to interannual variation in discharge recorded in river diatom frustules from an ocean sediment core

2017 ◽  
Vol 114 (38) ◽  
pp. 10155-10159 ◽  
Author(s):  
John B. Sculley ◽  
Rex L. Lowe ◽  
Charles A. Nittrouer ◽  
Tina M. Drexler ◽  
Mary E. Power
Keyword(s):  
Food Web ◽  
Sediment Core ◽  
Nutrient Loading ◽  
Field Research ◽  
Growth Conditions ◽  
Early Summer ◽  
Depositional Environments ◽  
Annual Rainfall ◽  
Algal Production ◽  
Positive Effects

Little is known about the importance of food-web processes as controls of river primary production due to the paucity of both long-term studies and of depositional environments which would allow retrospective fossil analysis. To investigate how freshwater algal production in the Eel River, northern California, varied over eight decades, we quantified siliceous shells (frustules) of freshwater diatoms from a well-dated undisturbed sediment core in a nearshore marine environment. Abundances of freshwater diatom frustules exported to Eel Canyon sediment from 1988 to 2001 were positively correlated with annual biomass ofCladophorasurveyed over these years in upper portions of the Eel basin. Over 28 years of contemporary field research, peak algal biomass was generally higher in summers following bankfull, bed-scouring winter floods. Field surveys and experiments suggested that bed-mobilizing floods scour away overwintering grazers, releasing algae from spring and early summer grazing. During wet years, growth conditions for algae could also be enhanced by increased nutrient loading from the watershed, or by sustained summer base flows. Total annual rainfall and frustule densities in laminae over a longer 83-year record were weakly and negatively correlated, however, suggesting that positive effects of floods on annual algal production were primarily mediated by “top-down” (consumer release) rather than “bottom-up” (growth promoting) controls.

Loss of spawning habitat and prerecruits of Pacific cod during a Gulf of Alaska heatwave

2020 ◽  
Vol 77 (4) ◽  
pp. 644-650 ◽  
Author(s):  
Benjamin J. Laurel ◽  
Lauren A. Rogers
Keyword(s):  
Time Series ◽  
Laboratory Data ◽  
Reproductive Potential ◽  
Gulf Of Alaska ◽  
Spawning Habitat ◽  
Pacific Cod ◽  
Pacific Cod Gadus Macrocephalus ◽  
Gadus Macrocephalus ◽  
Hatch Success ◽  
Negative Impacts

Pacific cod (Gadus macrocephalus) stocks in the Gulf of Alaska experienced steep, unexpected declines following an unprecedented 3-year marine heatwave (i.e., “warm blob”) from 2014 to 2016. We contend that stock reproductive potential was reduced during this period, evidenced by a combination of new laboratory data demonstrating narrow thermal hatch success (3–6 °C), mechanistic-based models of spawning habitat, and correlations with prerecruit time series. With the exception of single-year El Niño events (1998, 2003), the recent 3-year heatwave (2014–2016) and return to similar conditions in 2019 were potentially the most negative impacts on spawning habitat for Pacific cod in the available time series (1994–2019). Continued warming will likely reduce the duration and spatial extent of Pacific cod spawning in the Gulf of Alaska.

Development, Growth, and Survival of Lepeophtheirus Salmonis (Copepoda: Caligidae) Under Laboratory Conditions

1991 ◽  
Vol 71 (2) ◽  
pp. 425-436 ◽  
Author(s):  
S. C. Johnson ◽  
L. J. Albright
Keyword(s):  
Adult Female ◽  
Survival Data ◽  
Laboratory Experiments ◽  
Development Time ◽  
Lepeophtheirus Salmonis ◽  
Survival Times ◽  
Growth And Survival ◽  
Average Survival ◽  
Copepodid Stage ◽  
The Mean

Development, growth, and survival data derived from laboratory experiments are provided for Lepeophtheirus salmonis, a common ectoparasite of wild and sea-farmed salmonids. The mean development time of eggs was 419·1 hours (17·5 days) at 5°C, 207·1 hours (8·6 days) at 10°C, and 130·8 hours (5·5 days) at 15°C. Development from the first nauplius to the infectious copepodid stage took 222·3 hours (9·3 days) at 5°C, 87·4 hours (3·6 days) at 10°C, and 44·8 (1·9 days) hours at 15°C. Development from the egg to the adult male took 40 days, and from the egg to the adult female 52 days at 10°C. No egg development occurred at 10‰ salinity. At 15‰ eggs developed but failed to produce active nauplii. At higher salinities (20–3‰) active nauplii were produced, but copepodids were only obtained at 30‰. Copepodids survived for less than 1 day in waters with a salinity of 10‰ or less. At higher salinities (15–30‰) and temperatures of 5,10, and 15°C average survival times ranged between 2 and 8 days.

Elevated temperature and CO2 have positive effects on the growth and survival of larval Australasian snapper

2020 ◽  
Vol 161 ◽  
pp. 105054
Author(s):  
Shannon J. McMahon ◽  
Darren M. Parsons ◽  
Jennifer M. Donelson ◽  
Steve M.J. Pether ◽  
Philip L. Munday
Keyword(s):  
Elevated Temperature ◽  
Growth And Survival ◽  
Positive Effects

scholarly journals The role of temperature on the growth and survival of early and late hatching Pacific cod larvae (Gadus macrocephalus)

2008 ◽  
Vol 30 (9) ◽  
pp. 1051-1060 ◽  
Author(s):  
B. J. Laurel ◽  
T. P. Hurst ◽  
L. A. Copeman ◽  
M. W. Davis
Keyword(s):  
Pacific Cod ◽  
Growth And Survival ◽  
Gadus Macrocephalus

scholarly journals Growth, mortality, and recruitment signals in age-0 gadids settling in coastal Gulf of Alaska

2016 ◽  
Vol 73 (9) ◽  
pp. 2227-2237 ◽  
Author(s):  
Benjamin J. Laurel ◽  
Brian A. Knoth ◽  
Clifford H. Ryer
Keyword(s):  
Early Life History ◽  
Gulf Of Alaska ◽  
Walleye Pollock ◽  
First Year ◽  
Pacific Cod ◽  
Temperature Dependent ◽  
Gadus Macrocephalus ◽  
Class Strength ◽  
Saffron Cod ◽  
Recruitment Signals

Abstract Age-0 juveniles may be the earliest, reliable indicators of recruitment into commercial marine fisheries, but independent fisheries assessments are usually conducted on older life stages in adult habitats. We used an 8 year juvenile gadid survey along the coast of Kodiak, Alaska to examine annual abundance, growth and mortality in age-0 Pacific cod (Gadus macrocephalus), with comparisons to saffron cod (Eleginus gracilis) and walleye pollock (Gadus chalcogrammus) where possible. Annual abundance of age-0 fish was positively correlated among all three species, suggesting Pacific gadids respond similarly to processes controlling pre-settlement survival and/or delivery to coastal nurseries. In Pacific cod, June temperature was positively correlated with size-at-settlement but post-settlement growth was density- rather than temperature-dependent. Age-0 abundance indices for Pacific and saffron cod predicted the number of age-1 fish the following year (i.e. positive “recruitment signals”), but only in the larger nursery (Anton Larsen Bay) where age-1 gadids were more likely to remain resident after their first year. Recruitment signals for Pacific cod improved with later estimates of age-0 abundance, likely because of high mortality following settlement in July. In contrast, very few age-0 and age-1 walleye pollock were caught across the entire time-series of the survey. Collectively, these data suggest that nearshore surveys may be a tractable means of examining early life history processes and assessing year-class strength in juvenile Pacific and saffron cod, but have relatively low value in understanding the population dynamics of walleye pollock.

scholarly journals Using a climate attribution statistic to inform judgments about changing fisheries sustainability

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Michael A. Litzow ◽  
Michael J. Malick ◽  
Alisa A. Abookire ◽  
Janet Duffy-Anderson ◽  
Benjamin J. Laurel ◽  
...  
Keyword(s):  
Climate Adaptation ◽  
Climate Extremes ◽  
Gulf Of Alaska ◽  
Fish Population ◽  
Bayesian Regression ◽  
Pacific Cod ◽  
Gadus Macrocephalus ◽  
Fisheries Sustainability ◽  
Population Processes ◽  
Historical Range

AbstractSustainability—maintaining catches within the historical range of socially and ecologically acceptable values—is key to fisheries success. Climate change may rapidly threaten sustainability, and recognizing these instances is important for effective climate adaptation. Here, we present one approach for evaluating changing sustainability under a changing climate. We use Bayesian regression models to compare fish population processes under historical climate norms and emerging anthropogenic extremes. To define anthropogenic extremes we use the Fraction of Attributable Risk (FAR), which estimates the proportion of risk for extreme ocean temperatures that can be attributed to human influence. We illustrate our approach with estimates of recruitment (production of young fish, a key determinant of sustainability) for two exploited fishes (Pacific cod Gadus macrocephalus and walleye pollock G. chalcogrammus) in a rapidly warming ecosystem, the Gulf of Alaska. We show that recruitment distributions for both species have shifted towards zero during anthropogenic climate extremes. Predictions based on the projected incidence of anthropogenic temperature extremes indicate that expected recruitment, and therefore fisheries sustainability, is markedly lower in the current climate than during recent decades. Using FAR to analyze changing population processes may help fisheries managers and stakeholders to recognize situations when historical sustainability expectations should be reevaluated.

scholarly journals Effects of Microplastics on the Feeding Rates of Larvae of a Coastal Fish: Direct Consumption, Trophic Transfer, and Effects on Growth and Survival

2021 ◽  
Author(s):  
Christine Uy ◽  
Darren Johnson
Keyword(s):  
Larval Fish ◽  
Trophic Transfer ◽  
Control Group ◽  
Feeding Rates ◽  
Lower Growth ◽  
Larval Phase ◽  
Coastal Fish ◽  
Growth And Survival ◽  
Low Concentrations ◽  
High Concentrations

Abstract Microplastics are now found throughout the world’s oceans, and although many organisms ingest microplastics, less is known about how plastics in seawater may affect key processes such as feeding rate, growth, and survival. We used a series of laboratory experiments to test whether microplastics in seawater affected the feeding rates of larvae of the California Grunion, Leuresthes tenuis. In addition, we tested whether trophic transfer of microplastics from zooplankton to larval fish can occur and affect growth and survival of fish. We measured feeding rates of grunion larvae at various concentrations of 75–90 µm and 125–250 µm polyethylene microplastics and under both still water and turbulent conditions. In these experiments, exposure to microplastics had modest effects on feeding rates, though responses may be somewhat complex. Low concentrations of microplastics increased feeding rates compared to the control, but at higher concentrations, feeding rates were indistinguishable from those in the control group though effects were small compared to natural variation in feeding rates among individual fish. Experiments to test for trophic transfer of microplastics revealed that grunion larvae that were fed brine shrimp exposed to high concentrations of microplastics had lower growth rates and elevated mortality rates. Overall, our results suggest that the direct effects of microplastics on feeding rates of California Grunion during the early larval phase are minor, while the trophic transfer of microplastics from zooplankton to larval fish may have significant effects on their growth and survival.

scholarly journals Interaction between the Knowledge Sharing on Innovation Behavior Based on the Viewpoint of Team Diversity: Empirical Research from China

2019 ◽  
Vol 64 ◽  
pp. 97-107 ◽  
Author(s):  
Meng-Hsiu LEE ◽  
Ming-Yu YEN ◽  
Louis PERROMAT
Keyword(s):  
Knowledge Sharing ◽  
Organizational Performance ◽  
High Tech ◽  
High Tech Industry ◽  
Mutual Cooperation ◽  
Growth And Survival ◽  
Team Diversity ◽  
Continuous Innovation ◽  
Positive Effects ◽  
Innovation Behavior

In the rapidly changing and challenging environment, the possession of continuous innovation ability is primary for organizations in high-tech industry, which have to constantly apply innovation to maintain and enhance the effectiveness, create corporate value, and pursue organizational excellence so as to promote the competitive advantage for enterprise growth and survival. For organizations toady, work teams are the basic units to complete tasks. A lot of management activities are mostly preceded with teams, relying on the mutual cooperation among members. Besides, team interaction and communication could effectively enhance team performance and organizational performance. Aiming at supervisors and employees of high-tech industry in Fujian Province, total 520 copies of questionnaire are distributed, and 351 valid copies are retrieved, with the retrieval rate 68%. The research results show that 1.team diversity presents positive and significant effects on knowledge sharing, 2.knowledge sharing shows positive and remarkable effects on innovation behavior, and 3.team diversity reveals positive effects on innovation behavior. According to the results, suggestions are proposed, expecting to stimulate team innovation behaviors for high-tech industry applying different value, experience, and professional knowledge of team members.

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