scholarly journals Habitat Use Throughout a Chondrichthyan's Life

2021 ◽  
Author(s):  
◽  
Melissa Marquez
Keyword(s):  
Risk Assessment ◽  
Life History ◽  
New Zealand ◽  
Habitat Use ◽  
Fish Distribution ◽  
Life History Stage ◽  
Nursery Ground ◽  
Data Set ◽  
Life History Stages ◽  
Species Vulnerability

<p>Over the last few decades, much effort has been devoted towards evaluating and reducing bycatch in marine fisheries. There has been a particular focus on quantifying the risk to chondrichthyans, primarily because of their relatively high vulnerability to overfishing. A key part of risk assessment is evaluating the distributional overlap of the fish with the fisheries, where fish distribution is influenced by habitat use. I synthesised published observations of habitat use for different life history stages of chondrichthyans and hypothesised the associated catch composition in terms of fish sex, size, and maturity. I then searched for these catch compositions, and thereby locations, using New Zealand research vessel catch data. Results show that some life history stages and habitats for certain species can be identified, whereas others could not. Pupping ground criteria were met for Callorhynchus milii (ELE), Hydrolagus novaezealandiae (GSH), and Hydrolagus bemisi (GSP); nursery ground criteria were met for Callorhynchus milii (ELE), mating ground criteria were met for Callorhynchus milii (ELE), Hydrolagus novaezealandiae (GSH), Hydrolagus bemisi (GSP), and Harriotta raleighana (LCH); lek-like mating criteria were met for Hydrolagus novaezealandiae (GSH). For those life-history stage habitats not found, this may be because these are outside of the coverage of the data set (and likely also commercial fisheries), or because they do not actually exist for some chondrichthyans. On the basis of results, I propose to change the order of species in the New Zealand qualitative (Level 1) risk assessment, and rise the relative risk for Hydrolagus bemisi (GSP), given the species vulnerability of pupping grounds.</p>

scholarly journals Habitat Use Throughout a Chondrichthyan's Life

2021 ◽  
Author(s):  
◽  
Melissa Marquez
Keyword(s):  
Risk Assessment ◽  
Life History ◽  
New Zealand ◽  
Habitat Use ◽  
Fish Distribution ◽  
Life History Stage ◽  
Nursery Ground ◽  
Data Set ◽  
Life History Stages ◽  
Species Vulnerability

<p>Over the last few decades, much effort has been devoted towards evaluating and reducing bycatch in marine fisheries. There has been a particular focus on quantifying the risk to chondrichthyans, primarily because of their relatively high vulnerability to overfishing. A key part of risk assessment is evaluating the distributional overlap of the fish with the fisheries, where fish distribution is influenced by habitat use. I synthesised published observations of habitat use for different life history stages of chondrichthyans and hypothesised the associated catch composition in terms of fish sex, size, and maturity. I then searched for these catch compositions, and thereby locations, using New Zealand research vessel catch data. Results show that some life history stages and habitats for certain species can be identified, whereas others could not. Pupping ground criteria were met for Callorhynchus milii (ELE), Hydrolagus novaezealandiae (GSH), and Hydrolagus bemisi (GSP); nursery ground criteria were met for Callorhynchus milii (ELE), mating ground criteria were met for Callorhynchus milii (ELE), Hydrolagus novaezealandiae (GSH), Hydrolagus bemisi (GSP), and Harriotta raleighana (LCH); lek-like mating criteria were met for Hydrolagus novaezealandiae (GSH). For those life-history stage habitats not found, this may be because these are outside of the coverage of the data set (and likely also commercial fisheries), or because they do not actually exist for some chondrichthyans. On the basis of results, I propose to change the order of species in the New Zealand qualitative (Level 1) risk assessment, and rise the relative risk for Hydrolagus bemisi (GSP), given the species vulnerability of pupping grounds.</p>

scholarly journals Effects of life history stage and climatic conditions on fecal egg counts in plains zebras (Equus quagga) in the Serengeti National Park

2020 ◽  
Vol 119 (10) ◽  
pp. 3401-3413
Author(s):  
Peter A. Seeber ◽  
Tetiana A. Kuzmina ◽  
Alex D. Greenwood ◽  
Marion L. East
Keyword(s):  
Life History ◽  
Environmental Conditions ◽  
National Park ◽  
Climatic Conditions ◽  
Life History Stage ◽  
Gastrointestinal Parasite ◽  
Serengeti Ecosystem ◽  
Life History Stages ◽  
Lactating Females ◽  
Host Life

Abstract In wildlife, endoparasite burden can be affected by host life history stage, environmental conditions, host abundance, and parasite co-infections. We tested the effects of these factors on gastrointestinal parasite infection in plains zebras (Equus quagga) in the Serengeti ecosystem, Tanzania, using fecal egg counts of two nematode families (Strongylidae and Ascarididae) and the presence/absence of cestode (Anoplocephalidae) eggs. We predicted higher egg counts of Strongylidae and Ascarididae, and increased likelihood of Anoplocephalidae infection in individuals (1) during energetically costly life history stages when resource allocation to immune processes may decrease and in young zebras after weaning because of increased uptake of infective stages with forage, (2) when climatic conditions facilitate survival of infective stages, (3) when large zebra aggregations increase forage contamination with infective stages, and (4) in individuals co-infected with more than one parasite group as this may indicate reduced immune competence. Strongylidae egg counts were higher, and the occurrence of Anoplocephalidae eggs was more likely in bachelors than in band stallions, whereas Ascarididae egg counts were higher in band stallions. Strongylidae and Ascarididae egg counts were not increased in lactating females. Strongylidae egg counts were higher in subadults than in foals. Regardless of sex and age, Ascarididae infections were more likely under wet conditions. Co-infections did not affect Strongylidae egg counts. Ascarididae egg counts in adult females were higher when individuals were co-infected with Anoplocephalidae. We present evidence that parasite burdens in plains zebras are affected by life history stage, environmental conditions, and co-infection.

Diversity in immature-shark communities along a tropical coastline

2015 ◽  
Vol 66 (5) ◽  
pp. 399 ◽  
Author(s):  
Peter M. Yates ◽  
Michelle R. Heupel ◽  
Andrew J. Tobin ◽  
Stephen K. Moore ◽  
Colin A. Simpfendorfer
Keyword(s):  
Life History ◽  
Spatial Ecology ◽  
Population Level ◽  
Interspecific Variation ◽  
Eastern Coast ◽  
Life History Stage ◽  
Shark Species ◽  
Life History Stages ◽  
Young Of The Year ◽  
Effective Conservation

Effective conservation and management of shark populations is complicated by our limited understanding of their spatial ecology. For example, there are scarce data on diversity in community structure and nursery function across broader geographic scales (e.g. across multiple inshore systems) and the implications of this diversity for shark populations. Accordingly, fishery-independent surveys were undertaken to investigate shark communities along ~400km of the tropical eastern coast of Australia (18.1–20.6°S, 146.0–148.8°E). A variety of shark species were encountered, with 19 species of Carcharhiniformes contributing 99.2% of the total shark catch. Of the 1806 sharks captured, 567 were immature, including 336 young-of-the-year individuals. Immature sharks from 18 species were present; however, interspecific variation in the proportions of life-history stages was apparent. Multivariate analyses identified significant spatial heterogeneity in immature-shark communities. Results also highlighted the importance of tropical coastal habitats for numerous shark species, and indicated community-wide spatial structuring of sharks on the basis of body size rather than life-history stage. In addition to building on traditional shark-nursery paradigms, these results demonstrated that data on nursery function from restricted areas may not accurately portray patterns occurring over broader geographic scales, and this diversity may provide population-level benefits for sharks.

Nutrients in Salmonid Ecosystems: Sustaining Production and Biodiversity

2003 ◽  
Keyword(s):  
Life History ◽  
North America ◽  
Ecosystem Function ◽  
Pacific Salmon ◽  
Life History Stage ◽  
High Productivity ◽  
Life History Stages ◽  
Ecosystem Effects ◽  
Precipitous Decline ◽  
Northwestern North America

<em>Abstract.</em>—Pacific salmon <em>Oncorhynchus </em>spp. are important components of numerous food webs throughout their life history, yet we know very little about the historic and current abundance of these life history stages. We used past cannery records, recent harvest and hatchery records, and salmon life history information drawn from the literature to construct a simple bioregional model of historic and recent salmon abundance at egg, fry, smolt, ocean adult, and spawning stages for five species of Pacific salmon from Alaska to California. We found a historic-to-recent bioregional decline in salmon biomass in all life history stages. Recent salmon egg, fry, smolt, ocean-going adult, and escapement biomass estimates for northwestern North America are 74%, 55%, 59%, 86%, and 35%, respectively, of historic levels. Recent high productivity in Alaskan waters, however, masks a precipitous decline south of Alaska, where recent egg, fry, smolt, ocean-going adult, and escapement biomass levels are 34%, 23%, 50%, 40%, and 15% that of historic levels. Adult production and harvest levels are no longer sufficient measures of salmon management success. Researchers need to quantify and elucidate the ecosystem effects of historic biomass changes in life history stages of Pacific salmon on a watershed basis. Fisheries managers must set and meet specific targets for salmon life history stage abundance—from egg to spawning adult—to restore and maintain ecosystem function.

scholarly journals Organization of vertebrate annual cycles: implications for control mechanisms

2007 ◽  
Vol 363 (1490) ◽  
pp. 425-441 ◽  
Author(s):  
John C Wingfield
Keyword(s):  
Life History ◽  
Environmental Conditions ◽  
Environmental Variation ◽  
Life History Stage ◽  
Control Mechanisms ◽  
Phenotypic Flexibility ◽  
Endocrine Control ◽  
Annual Cycles ◽  
Life History Stages ◽  
The Individual

The majority of vertebrates have a life span of greater than one year. Therefore individuals must be able to adapt to the annual cycle of changing conditions by adjusting morphology, physiology and behaviour. Phenotypic flexibility, in which an individual switches from one life history stage to another, is one way to maximize fitness in a changing environment. When environmental variation is low, few life history stages are needed. If environmental variation is large, there are more life history stages. Each life history stage has a characteristic set of sub-stages that can be expressed in various combinations and patterns to determine state at any point in the life of the individual. Thus individuals have a finite number of states that can be expressed over the spectrum of environmental conditions in their life spans. Life history stages have three phases–development, mature capability (when characteristic sub-stages can be expressed) and termination. Expression of a stage is time dependent (probably a minimum of one month), and termination of one stage overlaps development of the next stage. It follows that the more life history stages an individual expresses, the less flexibility it will have in timing those stages. Having fewer life history stages increases flexibility in timing, but less tolerance of variation in environmental conditions. To varying degrees it is possible to overlap mature capability of some life history stages to effectively reduce ‘finite stage diversity’ and maximize flexibility in timing. Theoretical ways by which this can be done, and the implications for neuroendocrine and endocrine control mechanisms are discussed. Twelve testable hypotheses are posed that relate directly to control mechanisms.

scholarly journals Palaeodemographics of individuals in Dinaledi Chamber using dental remains

2018 ◽  
Vol 114 (1/2) ◽  
Author(s):  
Debra R. Bolter ◽  
John Hawks ◽  
Barry Bogin ◽  
Noel Cameron
Keyword(s):  
Life History ◽  
Dental Material ◽  
Data Set ◽  
Life History Stages ◽  
Old Adult ◽  
Minimum Number ◽  
Fossil Hominins ◽  
Minimum Number Of Individuals ◽  
Number Of Individuals ◽  
High Representation

Hominin skeletal remains from the Dinaledi Chamber, South Africa, represent a minimum of 15 individuals of the extinct species Homo naledi. We examined the dental material from this sample in order to assess the life-history stages of individuals in the sample, in particular to determine the minimum number of individuals in the sample as a whole, and within each of six age classes. We found evidence of individuals within every age class: infant, early juvenile, late juvenile, subadult, young adult and old adult. The Dinaledi Chamber sample is notable in comparison to other samples of human, chimpanzee and fossil hominins in that it has a relatively high representation of juvenile remains, as compared to infants and adults. With 15 individuals, the sample size presented by the Dinaledi dental material is too small to test the hypothesis of attritional versus catastrophic accumulation. The data here provide a basis for further investigation of individual associations within this commingled assemblage, and provide an important comparative data set as a basis for the consideration of life history in H. naledi and other extinct hominin populations.

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.

scholarly journals Experimental heating reveals nest temperature affects nestling condition in tree swallows ( Tachycineta bicolor )

2008 ◽  
Vol 4 (5) ◽  
pp. 468-471 ◽  
Author(s):  
Jonathan H Pérez ◽  
Daniel R Ardia ◽  
Elise K Chad ◽  
Ethan D Clotfelter
Keyword(s):  
Life History ◽  
Body Mass ◽  
Body Condition ◽  
Tachycineta Bicolor ◽  
Tree Swallow ◽  
Life History Stage ◽  
Delayed Effects ◽  
Life History Stages ◽  
Treatment Status ◽  
Carry Over

Investment in one life-history stage can have delayed effects on subsequent life-history stages within a single reproductive bout. We experimentally heated tree swallow ( Tachycineta bicolor ) nests during incubation to test for effects on parental and nestling conditions. Females incubating in heated boxes maintained higher body condition and fed nestlings at higher rates. We cross-fostered nestlings and found that young nestlings (4–7 days old) incubated in heated nests had higher body condition and body mass, regardless of treatment status of their rearing parent. However, older nestlings which were fed by heated females maintained higher condition and body mass regardless of treatment status of their incubating parent. These results indicate that investment in one life-history stage can have multiple pathways of carry-over effects on future life-history stages.

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