scholarly journals Notes on age determination, size and age structure, longevity, and growth of co‐occurring macrourid fishes

2021 ◽  
Author(s):  
Odd Aksel Bergstad ◽  
Rebecca H. Hunter ◽  
Nicola J. Cousins ◽  
David M. Bailey ◽  
Terje Jørgensen
Keyword(s):  
Age Structure ◽  
Age Determination ◽  
Size And Age Structure

scholarly journals Morphometric differentiation and geographic variation among populations of Boana cordobae (Anura: Hylidae): effect to age

2018 ◽  
Vol 66 (4) ◽  
pp. 1401
Author(s):  
Mariana Baraquet ◽  
Manuel Alejandro Otero ◽  
Pablo Raúl Grenat ◽  
María Selene Babini ◽  
Adolfo Ludovico Martino
Keyword(s):  
Body Size ◽  
Geographic Variation ◽  
Age Structure ◽  
Age Determination ◽  
High Elevation ◽  
San Luis ◽  
Size And Age Structure ◽  
Effect Of Age ◽  
Main Factor

We estimated differences in body size and age structure of six populations of Boana cordobae living at different altitudes, 808-2 310 m.a.s.l. in Córdoba and San Luis provinces (Argentina). We measured 15 morphometric variables and used skeletochronology to age determination of 79 individuals. Morphometric variables showed significant differences between sexes, being females larger than males, even when the effect of age was taken into account. We found a significant relationship between age and most of the morphometric variables. When removing the effects of age, we found significant inter-population differences in body size. Males from the high-elevation populations were larger than individuals from low-elevation populations. These results suggest that a difference in age structure between populations is a main factor for the geographic variation in body size of this species.

Response of Daphnia population size and age structure to predation

1975 ◽  
Vol 19 (4) ◽  
pp. 2898-2905
Author(s):  
Nelson G. Hairston ◽  
Robert A. Pastorok
Keyword(s):  
Population Size ◽  
Age Structure ◽  
Daphnia Population ◽  
Size And Age Structure

scholarly journals Projected Population Size and Age Structure for Canada and Provinces: With and Without International Migration

2007 ◽  
Vol 34 (2) ◽  
pp. 103 ◽  
Author(s):  
Shirley Loh ◽  
M. V. George
Keyword(s):  
Population Growth ◽  
International Migration ◽  
Age Structure ◽  
Current Level ◽  
The Other ◽  
Population Projections ◽  
Limited Effect ◽  
Continuous Increase ◽  
Size And Age Structure ◽  
The Impact

This paper examines the effect of net international migration on prospective population growth and age structure in Canada for the next 50 years. It also examines the impact of international migration on provincial growth and distribution. The procedure used in this study is by comparing two projected population scenarios, one with international migration and the other without international migration, based on the latest 2005-based population projections. The analysis of the scenarios shows that the assumed level of international migration which is higher than the current level contributes to a continuous increase in population over the next 50 years, but has limited effect to prevent or offset the overall aging trend.

Determining the most efficient method of age determination for estimating the age structure of a fish population

1995 ◽  
Vol 52 (11) ◽  
pp. 2320-2326 ◽  
Author(s):  
D. G. Worthington ◽  
A. J. Fowler ◽  
P. J. Doherty
Keyword(s):  
Sample Size ◽  
Age Structure ◽  
Sampling Error ◽  
Relative Size ◽  
Age Determination ◽  
Fish Population ◽  
Financial Cost ◽  
Economic Methods ◽  
Pomacentrus Moluccensis ◽  
Ageing Methods

Less precise, but economic methods for estimating the age of individual fish can provide better estimates of age structure than precise, but expensive methods. The benefits of using a precise ageing method can be compromised by its cost, which may restrict the size of the sample aged. If sample size is restricted, the effect of sampling error on an age structure may be greater than the effect of ageing error from a less precise ageing method that does not restrict sample size. We used Monte Carlo simulations to assess the relative size of sampling and ageing errors when estimating the age structure of populations of Pomacentrus moluccensis from the southern Great Barrier Reef, Australia. Sampling error associated with ageing less than 200 individuals was, on average, larger than the effects of most commonly reported ageing errors. Other factors that may complicate this comparison of ageing methods involve the financial cost of different methods and the logistics of sampling more fish.

scholarly journals Physiological Age Structure andLeishmaniaspp. Detection inPhlebotomus (Larroussius) orientalis(Parrot, 1936) (Diptera: Psychodidae) at an Endemic Focus of Visceral Leishmaniasis in Northern Ethiopia

2015 ◽  
Vol 2015 ◽  
pp. 1-7 ◽  
Author(s):  
Araya Gebresilassie ◽  
Ibrahim Abbasi ◽  
Oscar David Kirstein ◽  
Essayas Aklilu ◽  
Solomon Yared ◽  
...  
Keyword(s):  
Visceral Leishmaniasis ◽  
Age Structure ◽  
Leishmania Donovani ◽  
Age Determination ◽  
Blood Feeding ◽  
Physiological Age ◽  
Agricultural Fields ◽  
Northern Ethiopia ◽  
Sand Flies ◽  
Endemic Focus

Visceral leishmaniasis (VL) caused byLeishmania donovaniis endemic in northern Ethiopia, whereP. orientalisis the most important presumed vector. This study was designed to determine the physiological age structure and the occurrence ofLeishmaniainfection in the vector of VL in Tahtay Adiyabo district, northern Ethiopia. Sand flies were collected using CDC light traps from peridomestic and agricultural fields between May 2011 and April 2012 andP. orientalisfemales were dissected for age determination and detection ofLeishmaniapromastigotes. Sand flies were also analyzed forL. donovanidetection using molecular methods. Of 1,282P. orientalisexamined for abdominal stages and age characterization, 66.2%, 28.2%, 4.1%, and 1.6% were unfed, freshly fed, half-gravid, and gravid. Parous rate in unfed females was 34.1% and 35.4% in peridomestic and agricultural fields, respectively. Out of 921P. orientalisfemales dissected, one specimen (0.1%) was found naturally infected with promastigotes. Five pools (25 females) of unfedP. orientaliswere also found with DNA ofLeishmaniaspp. In particular, a singleP. orientaliswas positive forL. donovani(0.5%). Based on this and other evidences (abundance, human blood feeding, and xenodiagnostic studies),P. orientalisis the principal vector of VL in this endemic focus.

Age determination for female tsetse flies and the age compositions of samples ofGlossina pallidipesAust.,G. palpalis fuscipesNewst. andG. brevipalpisNewst.

1962 ◽  
Vol 53 (3) ◽  
pp. 579-595 ◽  
Author(s):  
D. S. Saunders
Keyword(s):  
Age Structure ◽  
Blood Meal ◽  
Reproductive System ◽  
Age Determination ◽  
Glossina Pallidipes ◽  
Tsetse Flies ◽  
Third Instar Larvae

The age compositions of samples of females ofGlossina pallidipesAust.,G. palpalis fuscipesNewst. andG. brevipalpisNewst., are analysed by means of a method of age determination based upon the changes occurring in the reproductive system during successive gonotrophic cycles. This method of age determination is described in detail.Females were sampled by three main methods: in traps, by catching on a bait-animal, and on a fly-round. Some flies were also found as resting flies in the undergrowth.Trap-caught samples ofG. pallidipeswere older (i.e.), contained a larger proportion of old flies (and a smaller proportion of young flies) than the hand-caught samples. The bait-caught samples were intermediate in age structure. Correlated with the increasing mean age in the hand-caught—bait-caught—trap-caught series was an increase in the proportion of females carrying third-instar larvae and a decrease in the proportion of those carrying eggs. Results with samples ofG. palpalis fuscipesandG. brevipalpiswere not so well defined.The results of dissecting teneral and non-teneral nullipars ofG. pallidipesandG. palpalis fuscipesindicate that females of the latter are inseminated some time before they take their first blood-meal, but teneral females ofG. pallidipesare inseminated when they come to the host to feed or after they have fed.The relation of the ovarian method of age determination to Jackson's (1946) wing-fray categories in females ofG. pallidipes, and the probable epidemiological importance of the samples, are also discussed.

Variation in the relationship between otolith weight and age: implications for the estimation of age of two tropical damselfish (Pomacentrus moluccensis and P. wardi)

1995 ◽  
Vol 52 (2) ◽  
pp. 233-242 ◽  
Author(s):  
D. O. Worthington ◽  
P. J. Doherty ◽  
A. J. Fowler
Keyword(s):  
Age Structure ◽  
Age Determination ◽  
Random Errors ◽  
Second Variation ◽  
Power Of Tests ◽  
Economic Method ◽  
Two Factors ◽  
Pomacentrus Moluccensis ◽  
The Relationship ◽  
Types Of Error

The weight of otoliths may provide an objective and economic method of ageing fish. To investigate this potential, populations of two species of fish (Pomacentrus moluccensis and P. wardi) were sampled from the lagoons of seven coral reefs within the Great Barrier Reef, Australia. The weight of otoliths increased with age throughout the life of both species. Two factors appeared to have the potential to undermine the use of otolith weight to estimate the age of individuals. First, overlap in the range of otolith weight among fish of different ages caused normally distributed errors in the subsequent estimation of age by otolith weight. Second, variation among reefs in the relationship between otolith weight and age biased subsequent age determinations. Both these types of error also affected the estimation of the age structure of the populations. Random errors in age determination resulted in the smoothing of the age structure whilst bias either shifted or compressed the age structure. While smoothing of an age structure will not compromise the results of several types of analysis, bias will be detrimental to most. Consequently, randomization methods were used to estimate the power of tests to detect variation in the relationship between otolith weight and age. Our results show that by frequently recalibrating the relationship between otolith weight and age, it can be used as an objective and economic method of age determination with the potential to be as reliable as counting annuli in sectioned otoliths.

Size and Age Structure of Anadromous and Landlocked Populations of Rainbow Smelt

2017 ◽  
Vol 37 (2) ◽  
pp. 326-336 ◽  
Author(s):  
Andrew J. O’Malley ◽  
Claire Enterline ◽  
Joseph Zydlewski
Keyword(s):  
Age Structure ◽  
Rainbow Smelt ◽  
Size And Age Structure
Sign in / Sign up

Export Citation Format

Share Document