Age, stucture, growth rates and movements of sea mullet, Mugil cephalus L., and Yellow-eye Mullet, Aldrichetta forsteri (Valenciennes), in the Swan-Avon river system, Western Australia

1981 ◽  
Vol 32 (4) ◽  
pp. 605 ◽  
Author(s):  
CF Chubb ◽  
IC Potter ◽  
CJ Grant ◽  
RCJ Lenanton ◽  
J Wallace
Keyword(s):  
Growth Rates ◽  
River System ◽  
First Year ◽  
Length Frequency ◽  
Frequency Distributions ◽  
Using Data ◽  
The Times ◽  
First Year Of Life ◽  
Breeding Seasons ◽  
System 1

The age structure, growth rates and movements of M. cephalus and A forsteri in the Swan-Avon river system have been investigated using data obtained from beach seining and gill netting carried out between February 1977 and June 1980. Length-frequency data and scale readings show that the populations of both species consist predominantly of 0+ and 1 + fish. From the times when the smallest fry (20-30 mm) were present in the lower part of the river system, and from the condition of the gonads of older fish, the breeding seasons of the sea and yellow-eye mullets have been estimated as extending from March to September and from March to August respectively. The bimodality or polymodality exhibited by the length-frequency distributions for the 0 + year classes suggest that in both species groups of individuals spawn at slightly different times. The range of mean total lengths and weights of animals caught in May near the end of the first year of life was 178-222 mm and 64-119 gin M. cephalus and 136-154 mm and 19-30 g in A. forsteri, which shows that the growth of each of these two species of mullet is relatively very rapid in the Swan-Avon river system. 1 + and 2 + fish tend to leave the estuary for varying periods. Although 0+ fish of both species utilized the shallow banks of the estuary throughout the year. the sea mullet moved further upstream and were not as consistently abundant in the lower estuary. Since 0+ yellow-eye mullet 40-100 mm long were also abundant in marine coastal waters between January and May. and sea mullet of comparable age were rarely observed in these regions, it would appear that M. cephalus is the more estuarine-dependent of the two species. Commercial catches of M. cephalus were greater than those of A. forsteri. This feature can be related in part to the much faster growth rate of M. cephalus, which results in a larger proportion of its youngest year classes reaching the minimum legal size for capture prior to the time when they leave the estuary in large numbers.

Age and growth of two commercially imported sharks (Carcharhinus tilstoni and C. sorrah) from Northern Australia

1988 ◽  
Vol 39 (4) ◽  
pp. 417 ◽  
Author(s):  
S Davenport ◽  
JD Stevens
Keyword(s):  
Growth Parameters ◽  
Age And Growth ◽  
First Year ◽  
Shark Species ◽  
Von Bertalanffy ◽  
Northern Australia ◽  
Length Frequency ◽  
Frequency Distributions ◽  
Gill Net ◽  
First Year Of Life

The age and growth of Carcharhinus tilstoni and C. sorrah, the two most abundant shark species in commercial gill-net catches off northern Australia, were investigated by the examination of vertebral rings. Corroborating evidence for age and growth estimates was obtained from length-frequency distributions and tag-recapture data. To aid validation of these estimates, tetracycline was injected into sharks at the time of tagging. Growth is relatively rapid in the first year of life: vertebral ageing indicated 17 cm growth in total length (TL) for C. tilstoni and about 20 cm for C. sorrah during the first year after birth. By the time the sharks are 5 years old, growth has declined to 8-10 cm per year in C. tilsoni and 5 cm per year or less in C. sorrah. The von Bertalanffy growth parameters for C. tilstoni are L∞ = 194.2, K = 0.14, t0 = -2.8 for females, and L∞ = 165.4, K = 0.19, t0 = -2.6 for males; for C. sorrah the parameters are L∞ = 123.9, K = 0.34, t0 = -1.9 for females, and L∞ = 98.4, K = 1.17, t0 = -0.6 for males. The greatest recorded ages for C. tilstoni were 12 years for females and 8 years for males, and for C. sorrah, 7 years for females and 5 years for males. Sexual maturity is reached early: at 3 to 4 years in C. tilstoni and 2 to 3 years in female C. sorrah.

scholarly journals Evaluation of Potential Overwinter Mortality of Age-0 Walleye and Appropriate Age-1 Sampling Gear

2018 ◽  
Vol 9 (1) ◽  
pp. 65-74 ◽  
Author(s):  
Jeffrey D. Grote ◽  
Melissa R. Wuellner ◽  
Brian G. Blackwell ◽  
David O. Lucchesi
Keyword(s):  
South Dakota ◽  
Body Condition ◽  
Relative Abundance ◽  
Coefficient Of Variation ◽  
First Year ◽  
Selective Mortality ◽  
Frequency Distributions ◽  
Abundance Indices ◽  
Overwinter Mortality ◽  
First Year Of Life

Abstract Potential recruitment of age-0 Walleye Sander vitreus to adults is often indexed by the relative abundance of age-0 individuals during their first summer or fall. However, relationships between age-0 and adult Walleye abundance are often weak or nonsignificant in many waters. Overwinter mortality during the first year of life has been hypothesized as an important limitation to Walleye recruitment in lakes, but limited evidence of such mortality exists, likely due to difficulties in sampling age-1 Walleye during spring. The objectives of this study were to: 1) compare results from nighttime electrofishing to index relative abundance of age-1 Walleyes with relative abundance indices of minifyke nets in four eastern South Dakota lakes; 2) determine whether size-selective mortality was occurring in those four lakes; and 3) if size-selective mortality was occurring in these lakes, determine whether that mortality was attributed to body condition. We sampled four natural lakes in eastern South Dakota 2 wk after ice-off in 2013 and 2014. Precision of nighttime electrofishing (coefficient of variation = 216.6) was greater than that estimated for minifyke nets (coefficient of variation = 338.5) across both years. We detected no differences in length-frequency distributions of collected spring age-1 Walleye between the two gears. Age-0 fall relative abundance indices from electrofishing were significantly greater (P < 0.01) than spring age-1 nighttime electrofishing indices of relative abundance at three of the four study lakes, indicating that overwinter mortality may occur at a substantial rate during the first year of life for Walleye in these systems. Quantile–quantile regression plots showed evidence of size-selective mortality in three of four lakes sampled. However, body condition of age-0 Walleye appeared to have little to no influence on overwinter mortality. Instead, we suggest that smaller-sized walleye may be more vulnerable to overwinter predation. Collectively, these results provide evidence of previously hypothesized overwinter mortality within the first year for Walleye and indicate possibilities for indexing potential adult recruitment of Walleye just after this critical period.

THE INFLUENCE OF REPRODUCTION ON BODY WEIGHT IN WOMEN

1957 ◽  
Vol 15 (4) ◽  
pp. 393-409 ◽  
Author(s):  
THOMAS McKEOWN ◽  
R. G. RECORD
Keyword(s):  
Body Weight ◽  
Early Pregnancy ◽  
Growth Rates ◽  
First Year ◽  
Weight Changes ◽  
Present Communication ◽  
Small Loss ◽  
One Year ◽  
First Year Of Life

SUMMARY 1. Data recorded in respect of all women whose children were born in a county borough during one year included the weight at the first antenatal examination (adjusted according to the number of days by which it preceded or followed the 124th day of gestation), and at 3, 6, 9, 12 and 24 months after delivery. The present communication is concerned with the influence of reproduction on body weight. 2. It is estimated that between conception and 24 months after birth women gained, on the average, approximately 6·6 lb. This is about 5 lb. more than would have been added in the same period if they had not been pregnant. Reasons are given for believing that these estimates may be a little low, probably not by more than 1 lb. 3. The increase in weight occurred mainly during pregnancy. From 3 months after delivery changes in mean weight were relatively small: a loss of 1·8 lb. between 3 and 12 months, and a gain of 0·6 lb. between 12 and 24 months. 4. The increment in mean weight between conception and 24 months increased slightly with parity, and, less certainly, with age. The most striking association with these variables occurred between 3 and 12 months after birth, when the proportion of women who gained weight decreased with increasing parity and increased with increasing age (Fig. 5). It is suggested that this relationship is probably attributable to an association between age and parity and social circumstances, and it is shown that the same trend was exhibited by the growth rates of the offspring of the same mothers during the first year of life (Fig. 6). 5. Lactation had little influence on mean weight. It resulted in a small loss during the period of lactation, but its effect was almost eliminated at 24 months after delivery (Fig. 7). 6. During the various intervals between early pregnancy and 24 months after delivery weight changes appear to be continuously distributed (Fig. 1). The constants of the distributions are given (Table 4).

Prevalence and Phenomenology of Neonaticide in Switzerland 1980–2010: A Retrospective Study

2015 ◽  
Vol 30 (2) ◽  
pp. 194-207 ◽  
Author(s):  
Paula Krüger
Keyword(s):  
Retrospective Study ◽  
Primary Objective ◽  
First Year ◽  
Prevention Strategies ◽  
Depth Analysis ◽  
German Speaking ◽  
Using Data ◽  
First Year Of Life

For a child, the likelihood of being murdered is highest during the first year of life, and many such cases are neonaticides. Although several recent studies have examined neonaticide in different countries and cultures, there has been no in-depth analysis of Swiss cases, even though this country has special neonaticide legislation and four “baby hatches” have been opened to prevent such killings. The primary objective of this retrospective study was to analyze the prevalence and phenomenon of neonaticide in Switzerland. Using data from judicial files, 11 cases were identified in 15 German-speaking cantons between 1980 and 2010. The sample included two uncommon cases of nonmaternal neonaticide. The discussion addresses possible prevention strategies.

Settlement and growth of the intertidal gastropod, Melarhaphe neritoides, on the south coast of Ireland

1993 ◽  
Vol 73 (2) ◽  
pp. 313-319 ◽  
Author(s):  
A. A. Myers ◽  
David McGrath
Keyword(s):  
Shell Height ◽  
South Coast ◽  
First Year ◽  
Rocky Shores ◽  
Length Frequency ◽  
The South ◽  
Frequency Distributions ◽  
Growth Increments ◽  
Intertidal Gastropod ◽  
Melarhaphe Neritoides

Settlement and growth of Melarhaphe neritoides (L. ) were studied on two rocky shores, at Carnsore Point, County Wexford and Tragumna, County Cork, on the south coast of Ireland during the years 1977–1978 and 1983–1991 respectively. Settlement occurred in each year but varied in timing and density, with maxima of 30,000 m-2 at Tragumna and 3,800 m-2 at Carnsore Point. Recently settled individuals occurred in pools in the Verrucaria zone and on open rock below this level. Growth of the 0+ and 1+ cohorts was determined by analysis of length frequency distributions. Growth of older snails was estimated by measuring growth increments in marked animals. Recruits grew to less than 2 mm in shell height in their first year. Larger snails (>2 mm shell height) grew 0. 2–0. 3 mm shell height per year. It is estimated that M. neritoides takes over five years to reach a shell height of 3 mm at Tragumna.

Environmental factors affecting growth of eastern sand darter (Ammocrypta pellucida)

2008 ◽  
Vol 86 (7) ◽  
pp. 714-722 ◽  
Author(s):  
D. A.R. Drake ◽  
M. Power ◽  
M. A. Koops ◽  
S. E. Doka ◽  
N. E. Mandrak
Keyword(s):  
Environmental Factors ◽  
Growth Rates ◽  
First Year ◽  
High Discharge ◽  
Factors Affecting ◽  
Growth Variability ◽  
Substrate Composition ◽  
Structured Population ◽  
Northern Edge ◽  
First Year Of Life

Environmental factors affecting growth of the threatened eastern sand darter ( Ammocrypta pellucida (Putnam, 1863)) were examined using specimens sampled from the northern edge of its range to determine the species’ critical habitat. Length-at-age increments were determined from scale samples as surrogates for growth rates based on back-calculated lengths using the Fraser–Lee method. During the first year of life, 82% of total length is attained, suggesting considerable energetic partitioning towards reproduction following age-0. Positive relationships between age-0 length increments and sand substrates and between age-0 length increments and mean annual channel discharge indicated greatest first-year growth within sand-dominated, high-discharge habitats. Environmental factors that occurred at coarse spatial and temporal levels (i.e., mean annual channel discharge) explained more of the growth variability among eastern sand darters than those occurring at fine levels (i.e., site-level substrate composition). This study indicates that environmental factors can be used to explain variability in cohort-structured population and site-level growth of eastern sand darters.

Age and Growth of the Capelin, Mallotus villosus (Müller), from Newfoundland and Grand Bank Areas

1958 ◽  
Vol 15 (3) ◽  
pp. 295-311 ◽  
Author(s):  
T. K. Pitt
Keyword(s):  
Growth Rates ◽  
Age And Growth ◽  
First Year ◽  
Length Frequency ◽  
Mallotus Villosus ◽  
Total Length ◽  
Capelin Mallotus Villosus ◽  
One Year

From the study of samples of capelin in their first year it was established that scales are acquired when the fish are a little less than one year old and range in size from 7.2 to 10.0 cm. total (extreme tip) length. Length frequency and age data indicate that there is great variation between the growth rates of the various year-classes.From the Grand Bank 96% of the mature males and 99.6% of the mature females were three years old. No five-year-old fish were found on the Grand Bank. The average total lengths of mature capelin from bank and shore areas are quite similar.The male capelin has a total length greater than that of the female. This difference increases from 0.22 cm. for one-year-old fish to 2.32 cm. for three-year-old spawning fish.

scholarly journals Parasite co-infections show synergistic and antagonistic interactions on growth performance of East African zebu cattle under one year

Parasitology ◽  
2013 ◽  
Vol 140 (14) ◽  
pp. 1789-1798 ◽  
Author(s):  
S. M. THUMBI ◽  
B. M. de. C. BRONSVOORT ◽  
E. J. POOLE ◽  
H. KIARA ◽  
P. TOYE ◽  
...  
Keyword(s):  
Growth Rate ◽  
Growth Rates ◽  
Daily Weight Gain ◽  
First Year ◽  
Zebu Cattle ◽  
Helminth Parasites ◽  
Lower Growth ◽  
One Year ◽  
First Year Of Life ◽  
Antagonistic Interactions

SUMMARYThe co-occurrence of different pathogen species and their simultaneous infection of hosts are common, and may affect host health outcomes. Co-infecting pathogens may interact synergistically (harming the host more) or antagonistically (harming the host less) compared with single infections. Here we have tested associations of infections and their co-infections with variation in growth rate using a subset of 455 animals of the Infectious Diseases of East Africa Livestock (IDEAL) cohort study surviving to one year. Data on live body weight, infections with helminth parasites and haemoparasites were collected every 5 weeks during the first year of life. Growth of zebu cattle during the first year of life was best described by a linear growth function. A large variation in daily weight gain with a range of 0·03–0·34 kg, and a mean of 0·135 kg (0·124, 0·146; 95% CI) was observed. After controlling for other significant covariates in mixed effects statistical models, the results revealed synergistic interactions (lower growth rates) with Theileria parva and Anaplasma marginale co-infections, and antagonistic interactions (relatively higher growth rates) with T. parva and Theileria mutans co-infections, compared with infections with T. parva only. Additionally, helminth infections can have a strong negative effect on the growth rates but this is burden-dependent, accounting for up to 30% decrease in growth rate in heavily infected animals. These findings present evidence of pathogen–pathogen interactions affecting host growth, and we discuss possible mechanisms that may explain observed directions of interactions as well as possible modifications to disease control strategies when co-infections are present.

scholarly journals Age and growth of the ommastrephid squid Todarodes sagittatus from the western Mediterranean Sea

2004 ◽  
Vol 84 (2) ◽  
pp. 421-426 ◽  
Author(s):  
Antoni Quetglas ◽  
Beatriz Morales-Nin
Keyword(s):  
Growth Rates ◽  
Somatic Growth ◽  
Western Mediterranean ◽  
Age And Growth ◽  
Length Frequency ◽  
Frequency Distributions ◽  
North West ◽  
Western Mediterranean Sea ◽  
Similar Work ◽  
The Mean

Age and growth of Todarodes sagittatus were estimated based on statolith analysis from individuals (N=352; 81–418 mm mantle length) caught by bottom trawlers during a year of sampling in the western Mediterranean. The daily nature of statolith increments was indirectly validated comparing the mean age of consecutive monthly modes (identified on the monthly length–frequency distributions) with the corresponding increase of 30 days. In agreement with other ommastrephids, results confirmed the following points: (1) lifespan lasts nearly a year; (2) growth rates decrease with age; (3) when adult, females have higher growth rates than males; and (4) females mature about a month later than males. Significant correlation was found between hatching (which occurred throughout the year but with a peak in November) and temperature at 50 m depth (where it is thought that hatchlings inhabit). Age and growth results were compared with those obtained in a similar work carried out in north-west Africa (Arkhipkin et al., 1999). Comparisons suggested that due to higher growth rates in juveniles, southern populations reach maturity and consequently decrease somatic growth at younger ages and smaller sizes than northern squid, which attain larger sizes as a result of maintaining fast growth and delaying maturation. Greater growth rates in juveniles from west Sahara could be explained by higher temperatures in this area than in the Mediterranean.

scholarly journals Variability in maturity and growth in a heavily exploited stock: cod (Gadus morhua L.) in the Irish Sea

2004 ◽  
Vol 61 (1) ◽  
pp. 98-112 ◽  
Author(s):  
M.J Armstrong ◽  
H.D Gerritsen ◽  
M Allen ◽  
W.J McCurdy ◽  
J.A.D Peel
Keyword(s):  
Gadus Morhua ◽  
Sex Ratios ◽  
Irish Sea ◽  
First Year ◽  
Spawning Grounds ◽  
Spawning Areas ◽  
The Irish Sea ◽  
Using Data ◽  
First Year Of Life ◽  
Over Time

Abstract Maturity, sex ratio (proportion female by number) and length-at-age of cod in the Irish Sea were examined using data collected during groundfish surveys in spring 1992–2002. Skewed sex ratios with a predominance of males were observed in the survey catches of 2- and 3-year-old cod taken on the spawning grounds. In contrast, commercial midwater trawl catches of cod in the same area had consistently higher sex ratios, suggesting that mature males and females have different vertical migration behaviour. Estimates of proportion mature were not affected by method of capture. In a GLM analysis, the factor age explained most of the variation in maturity in each sex, whilst length, although a significant factor, explained less variation than year and region (spawning and non-spawning grounds). Maturity was observed in a variable proportion of 2-year-olds, whilst virtually no 1-year-olds and all 3-year-olds and older were mature irrespective of area or year of capture. Population estimates of proportion mature in 2-year-olds, from all years' data combined, were 0.87 in males and 0.45 in females. Estimates were higher in spawning areas than in non-spawning areas, and showed a general increase over time throughout the survey area. However, in any year, the proportion mature at age 2 varied little with length and was reduced only in the smallest fish (<40 cm) at this age in some years. The increase over time in proportion mature coincided with rising sea surface temperature (SST) and a decline in recruitment and stock biomass at high rates of fishing mortality. Mean length-at-age differed consistently between year classes, the differences being largely established in the first year of life. The fastest growth rates were apparent in very weak year classes produced in the late 1990s when SST was relatively high. The interrelationships between growth, maturity, SST and abundance are examined, and changes in growth and maturity since earlier studies in the 1970s are investigated.

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