Interactions among adult demography, spawning date, growth rate, predation, overwinter mortality, and the recruitment of largemouth bass in a northern lake

1998 ◽  
Vol 55 (12) ◽  
pp. 2588-2600 ◽  
Author(s):  
David M Post ◽  
James F Kitchell ◽  
James R Hodgson

Using 12 years of data, we evaluated the mechanisms controlling largemouth bass, Micropterus salmoides, recruitment in a lake near the northern extent of the largemouth bass range. We found that complex interactions among adult demographics, size-selective predation, and overwinter mortality regulate the number of largemouth bass surviving the first year of life. The largest recruitment events required at least a moderate number of adults, but a large number of adults was not sufficient to produce a large cohort of largemouth bass. Predation was controlled by the number of both adult and juvenile bass and was not strongly correlated with reproductive output. Overwinter mortality was size dependent, strongly affecting bass entering the winter at <50-60 mm in length, and likely the result of starvation. Predation and overwinter mortality interacted with spawning date and growth rate to produce variable but predictable patterns of first year survival. At high adult and juvenile densities, predation regulates first year survival. At low adult and juvenile densities, first year survival was regulated by adult demographics and interactions among spawning date, growth rates, and overwinter mortality. Although we can forecast coarse patterns of cohort survival, the survival of individual fish was more difficult to predict because length and age were not highly correlated.

1974 ◽  
Vol 52 (4) ◽  
pp. 447-456 ◽  
Author(s):  
A. J. Niimi ◽  
F. W. H. Beamish

Changes in growth and proximate body composition of largemouth bass (Micropterus salmoides) were examined for fish of 8–150 g, between 18 and 30C. For most weights, growth of fish (grams/day) was highest at 25C, and lowest in fish at 18C. This was attributable in part to a higher satiation (maximum) feeding level at 25C. For a fixed level of feeding, growth rate (percentage wet weight/day) was highest for fish held at 18C.Lipid content (percentage wet weight) increased with feeding level and was highest at 18C, Moisture content varied inversely with lipid. Protein and ash content did not vary appreciably with temperature, body weight, or feeding level.Maintenance requirement of bass, expressed as grams/day, was about twice that lost during food deprivation, but only slightly different when expressed as kilocalories/day.Energy requirements for nonfecal losses were estimated as 10% of intake energy at all feeding levels. Standard metabolism accounted for 50% of intake energy near maintenance, but only 10% at the satiation feeding level. Growth requirements increased From zero at maintenance to 40% of intake energy at satiation feeding.


1969 ◽  
Vol 49 (1) ◽  
pp. 37-44 ◽  
Author(s):  
C. B. Bailey ◽  
R. Hironaka

The growth rate of bulls, steers castrated at 8 and 26 weeks of age, and steers partially castrated at 8 weeks of age did not differ before weaning in October at an average age of 181 days, or during the ensuing winter. During the subsequent finishing period in the feedlot, the rate and efficiency of growth of the partial castrates exceeded that of the steers but was less than that of the bulls. As a result, partial castrates reached the target slaughter weight of 440 kg 21 days earlier than the steers but 21 days later than the bulls. Varying the level of protein in the rations fed during the first 15 weeks of the feedlot period had no effect on rate or efficiency of gain.The percent fat in the 11th rib-cut and the depth of fat over the longissimus dorsi were less in bulls than in steers or partial castrates, and consequently the carcass grades of the bulls were generally lower. The percent separable muscle, estimated from a prediction equation, was greater in bulls than in steers and partial castrates.


2020 ◽  
pp. 24-32
Author(s):  
R.V. Marushko ◽  
◽  
О.О. Dudina ◽  
T.L. Marushko ◽  
◽  
...  

Ukraine entered the 21st century with one of the worst vital signs in Europe and the burden of many socio-economic and demographic problems. Adverse quantitative and especially qualitative indicators of population reproduction have become stable. Therefore, the most important medical and social task and one of the main activities of the Ministry of Health of Ukraine is the formation and maintenance of public health. The defining stage in the formation of human health is the first year of life. Purpose — to study the state and trends of changes in the main indicators of the health of children in the first year of life for the period 2000–2019. Materials and methods. A retrospective analysis of the incidence of children in the first year of life, infant mortality, over the past 20 years in the context of individual pathological conditions is carried out. The information base of the study was the data of state and industry statistics for 2000–2019. Methods of a systematic approach, statistical data processing, epidemiological analysis of graphic images were used. Results. The study revealed that the unfavorable demographic situation in Ukraine is accompanied by an unsatisfactory state of the main predictors of a healthy start in the life of infants, the formation and maintenance of their health. Over the past two decades, there has been a high level with a negative trend of diseases of the reproductive system of women, a high frequency of the combination of pregnancy and extragenital diseases remains. There is a negative trend towards an increase in the generalized objective criterion of the health of the generation, which is born and the socio-economic well-being of the population — the frequency of premature, low birth weight, incl. With very low birth weight. Only thanks to the introduction of modern medical organizational technologies with proven efficiency in the activities of the maternal and child health service was it possible to achieve a decrease in the incidence of newborns from 280.8 per 1000 live births in 2000 up to 172.14 in 2019. At the same time, the increase in the incidence of newborns with diseases that have a direct impact on the development of chronic and disabling diseases at all stages of life is of concern — congenital pneumonia, neonatal sepsis, other disorders of the cerebral status of the newborn, neonatal jaundice. According to the assessment of the dynamics of the general morbidity of children in the first year of life, its level is still high, with a positive trend — 2018.8 per 1000 children who reached 1 year in 2000 and 1393.1 in 2019, the growth rate is -30.9% with a traditionally leading position in the level and structure of the incidence of respiratory diseases — 810.2 per 1000 children who have reached one year of life and 58.15%, certain conditions occurring in perinatal period — 126.7 ‰ and 9.06%, diseases of the skin and subcutaneous tissue — 63.9‰ and 4.59%, diseases of the blood and hematopoietic organs and certain disorders involving the immune mechanism — 63.0‰ and 4.52%. Conclusions. The positive dynamics of morbidity in children of the first year of life is confirmed by a decrease in infant mortality from its maximum level of 11.9 per 1000 live births in 2000 up to 7.0 in 2019, the growth rate is -41.2% due to all its components with a more intensive reduction in postneonatal mortality from 5.28‰ to 2.57‰, the growth rate is -51.3% against the background of an increase in the concentration of mortality in the neonatal period from 55.9% to 64.5%, respectively. No conflict of interest was declared by the authors. Key words: newborns, children of the first year of life, low birthweight newborns, morbidity, infant mortality.


2019 ◽  
Author(s):  
Stefanie Riemer

AbstractNoise fears represent a highly prevalent welfare problem in dogs. An online survey was performed to explore severity and progression of firework fears in dogs, and relationships with demographics, health, behaviour problems, and owners’ training efforts to prevent or alleviate firework fears. 1225 responses were analysed. Fifty-two percent of dogs were at least partially affected by firework fears, and the great majority developed a fear of fireworks in the first year of life, with a decreasing frequency of new occurrences up until seven years, and only few newly affected dogs beyond this age. While almost three quarters of fearful dogs had recovered by the next morning, recovery took up to one day in 10%, up to one week in 12%, and several weeks or even months in >3%. Univariate analyses indicated a significant effect of breed group, age, sex, neuter status, origin and age at acquisition on severity of firework fears in dogs. However, binomial models including multiple predictors of presence/ absence of firework fears identified only age, breed group (mixed breeds being most affected), health problems, and an interaction between health problems and age as significant predictors. This discrepancy might be explained by collinearities of predictors and underlying differences between mixed-breed dogs and purebreds, such as mixed breeds being acquired from shelters more often, being adopted at higher ages, and being neutered more often. Firework fears are highly correlated with fears of gunshots and thunder, and to a low extent with fears of other noises, but not with any other behavioural problems. Both improvement and deterioration of firework fears were frequently reported. While an early age of onset and breed differences point to a strong genetic contribution to firework fears, training puppies or non-fearful adults to associate the noise with positive stimuli is highly effective in preventing later development of firework fears.


2018 ◽  
Vol 9 (1) ◽  
pp. 65-74 ◽  
Author(s):  
Jeffrey D. Grote ◽  
Melissa R. Wuellner ◽  
Brian G. Blackwell ◽  
David O. Lucchesi

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 &lt; 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.


Author(s):  
V. Vassilopoulou ◽  
I. Ondrias

This paper analyses the age and growth pattern of the four-spotted megrim (Lepidorhombus boscii), collected in the north Aegean Sea. The otoliths of the species exhibit bilateral asymmetry. Our data indicates that males have shorter lifespans (0–6 y) than females (0–8 y) and reach lower asymptotic lengths. A significant difference in growth rate exists between the two sexes after the first year of life. Growth in length is greater in females than males, whereas males appeared to be heavier than females of the same size. The latter was also corroborated by the higher accumulation of lipids in the muscle of males in relation to females. The growth rate of the species in the Atlantic was higher than in the Mediterranean. The oligotrophic character of the study area seemed to have a negative effect on the growth of megrims.


1991 ◽  
Vol 48 (S1) ◽  
pp. 58-65 ◽  
Author(s):  
David P. Philipp

Stocks of northern largemouth bass (NLMB), Micropterus salmoides salmoides, Florida largemouth bass (FLMB), M. s. floridanus, and both reciprocal F1 hybrids were produced through natural spawning; the genetic composition of each stock was confirmed electrophoreticaliy, and experimental populations established. One set of experimental populations (P1 and P2) contained as broodstock equal numbers of adult NLMB and FLMB, whereas the other set (H1 and H2) initially contained equal numbers of adults of both reciprocal F1 hybrids and both pure subspecies. Each year-class produced experimentally were sampled and individuals analyzed genetically to determine their parentage. Initially, much of the YOY production in P1 and P2 was composed of small FLMB that did not survive winter well; once naturally produced F1 hybrids entered the breeding pool, most offspring were Fx hybrids, and the population became heavily introgressed. In H1 and H2 introgression began with the production of the first year-class. Within each year-class NLMB produced in all ponds were significantly larger than all other genotypes, but it appears likely that after only a few generations, production of pure NLMB ceases, all individuals being Fx hybrids. Results illustrate the potential negative impacts of introducing FLMB or hybrids between it and NLMB into waters within or contiguous to the native range of the northern subspecies.


2004 ◽  
Vol 61 (3) ◽  
pp. 326-331 ◽  
Author(s):  
Ana Maria Barretto de Menezes Sampaio de Oliveira ◽  
José Eurico Possebon Cyrino

Adding attractants can improve acceptability of artificial diets by carnivorous fish fry and fingerlings, increasing intake of unpalatable feeds and improving growth rate, while reducing feeding time and feeding wastes. This study aimed to evaluate the effects of levels of inclusion of different attractants in plant protein-based diets on the performance of largemouth bass Micropterus salmoides. Nine hundred juvenile largemouth bass (26.54 ± 1.53 g) conditioned to accept dry, artificial feed were stocked in 60, 90-L polyethylene tanks (15 fish per group) in a completely randomized design trial (n=3). Fish were fed two daily meals ad libitum at 7h00 and 17h00, for 13 days, with a diet (100% plant protein source) containing either soluble fish protein - SFP (0.5, 1.0, 1.5, 2.0, 2.5, and 3.0%); FisharonTM - FA (0.02, 0.04, 0.06, 0.08, 0.10, 0.12%); fish silage - FS (1.0, 2.0, 3.0, 4.0, 5.0, and 6.0%); a positive control diet - pCD (10% fish meal) and a negative control diet - nCD (basal diet without attractants). DL-methionine (98%) and L-lysine (80%) were added automatically by the formulation software to adjust available amino-acid profile of diets. Recorded performance data were: final weight, feed intake, weight gain and feed conversion ratio. Fish fed diet FA0.02 presented the best growth rate, best weight gain and best feed conversion ratio. Fish fed diets containing FS as attractant presented the poorest performance.


1968 ◽  
Vol 19 (1) ◽  
pp. 1 ◽  
Author(s):  
JB Jillett

Age, growth, and food of a population of Acanthoclinus quadridactylus were studied from December 1959 to December 1960. Age and growth were investigated by means of length frequencies of fish and by the analysis of growth zones shown in their sagittal otoliths. The growth rate decreases with age and growth is retarded during winter months. Fish live to a maximum age of at least nine years at which time they are approximately 20 cm long. There are no marked differences in growth or longevity between the sexes. Analysis of gut contents showed that A. quadridactylus is an omnivorous carnivore. Diet is apparently restricted by availability rather than by selective feeding. Decapods were the most important food organisms and Petrolisthes elongatus was the most important single species. Other food organisms included (in order of importance) isopods, barnacles, amphipods, chitons, gastropods, bivalves, polychaetes, fish, and bryozoans. There is evidence of a change of diet in the first year of life.


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