Population biology of Urocleidus adspectus Mueller, 1936 (Monogenea) on Perca flavescens in New Brunswick

1985 ◽  
Vol 63 (2) ◽  
pp. 272-277 ◽  
Author(s):  
D. K. Cone ◽  
M. D. B. Burt
Keyword(s):  
New Brunswick ◽  
Population Biology ◽  
Perca Flavescens ◽  
Small Lakes ◽  
Length Frequency ◽  
Age Classes ◽  
Frequency Distributions ◽  
Short Generation Time ◽  
Seasonal Monitoring ◽  
Parasite Populations

The population biology of Urocleidus adspectus parasitizing gills of Perca flavescens in a small New Brunswick lake is described. The parasite has an annual cycle in which worms overwinter as inactive adults. In spring, they lay eggs and many worms die. A short generation time (14 days at 20 °C) allows transmission throughout summer and well into fall. Perch acquire infections during the first few months of life and thereafter annually lose and reacquire infections. The intensity of U. adspectus peaks during July and generally increases with age of the host. Length–frequency distributions of parasites on four host age-classes (1, 2, 3–4, and 5 and older) indicate that they grow larger on larger hosts. Seasonal monitoring of length–frequency distributions revealed that spring growth of overwintering worms and onset of spring invasion commence earlier on mature perch than on immature perch. The results are discussed in relation to our understanding of fish parasite populations in small lakes.

Size Distributions and Growth of the Fan-shell Pinna bicolor Gmelin (Mollusca : Eulamellibranchia) in South Australia

1979 ◽  
Vol 30 (1) ◽  
pp. 25 ◽  
Author(s):  
AJ Butler ◽  
FJ Brewster
Keyword(s):  
South Australia ◽  
Adductor Muscle ◽  
Size Distributions ◽  
Limited Data ◽  
Length Frequency ◽  
Age Classes ◽  
Frequency Distributions ◽  
Growth And Survival ◽  
Random Samples ◽  
Variable Success

Fourteen random samples of Pinna bicolor were collected over a period of 31 months from 6 m depth in Gulf St Vincent off Edithburgh, South Australia. The length-frequency distributions suggest that: P. bicolor larvae settle in spring but with variable success; growth of newly settled young is rapid over summer; by age 1 year their modal shell length is about 20 cm; by age 2 it is about 26 cm; they may survive substantially longer than 3 years so that a length-class of mode c. 35 cm is always present and is composed of several age-classes not necessarily equally represented. These suggestions are corroborated by limited data on adductor muscle scars, the development of epibiota on the shells, and the growth and survival of tagged animals over 9 months.

Application of the otolith weight – age relationship for the pilchard, Sardinops sagax neopilchardus

1995 ◽  
Vol 52 (4) ◽  
pp. 657-664 ◽  
Author(s):  
W. J. Fletcher
Keyword(s):  
Maximum Size ◽  
Steady Increase ◽  
Average Weight ◽  
Fish Length ◽  
Natural Mortality ◽  
Length Frequency ◽  
Age Classes ◽  
Frequency Distributions ◽  
Southwestern Australia ◽  
Sardinops Sagax

Adult pilchard (Sardinops sagax neopilchardus) from southwestern Australia held in fish cages for 1 year showed minimal increase in mean length but a steady increase in mean otolith weight (1.61–1.83 mg); this increase (0.22 mg) closely parallels the previously calculated mean difference between adjacent age classes (0.24 mg). Modes in otolith weight frequency distributions of fishery-caught pilchards, previously suggested as corresponding with separate year classes, generally persisted and progressed through subsequent samples. By contrast, fish length frequency distributions of these samples showed no consistent modal progression. The average weight of otoliths for year classes 2–8 were used to calculate growth rates: following sexual maturity, at age 2, males grew to a significantly smaller maximum size than females (L∞ = 162 and 172 mm respectively). The otolith weight – age relationship, validated by following a cohort of unusually low abundance as it moved through the fishery, indicated that recruitment to the fishery generally began at age 2 but was not complete until age 4. These data have been successfully used in forecasting the catch rate of the fishery up to 2 years in advance and providing an estimate of the rate for natural mortality of 0.43.

A population study of Galathea intermedia (Crustacea: Decapoda: Anomura) in the German Bight

2003 ◽  
Vol 83 (1) ◽  
pp. 133-141 ◽  
Author(s):  
Katrin Kronenberger ◽  
Michael Türkay
Keyword(s):  
Sex Ratio ◽  
Population Biology ◽  
Abdominal Segment ◽  
Morphological Characters ◽  
Adult Males ◽  
Length Frequency ◽  
Relative Growth ◽  
Frequency Distributions ◽  
Squat Lobster ◽  
Growth And Reproduction

The objectives of this study were to assess population biology and dynamics of the squat lobster Galathea intermedia. On the basis of nearly regular monthly samples taken with a 2-m beam trawl in the Helgoland trench (HTR) during the period of 1985 until 1992, sex ratio, length composition, relative growth and reproduction were studied. The overall sex ratio deviates significantly from 1:1 with 1[male ]:1·8[female] (P[les ]0·001). On average, sexes are equally large, but adult females attain a slightly larger size than adult males. No sex-specific differences in the length–weight relationship were found. Relative growth of the first abdominal segment is clearly of sexual-dimorphic character. On the basis of the length–frequency distributions, the life cycle of the HTR population lasts between one and two years. According to the appearance of ovigerous females and juveniles, reproduction and recruitment are clearly seasonal. Recruitment takes place between July and December. The main reproduction begins in April and ends in September, with a peak between June and August. A significant increase of specimens showing both male and female morphological characters, referred to as morphological hermaphrodites (P[les ]0·001), and males (P[les ]0·05) respectively, was detected.

Age and growth of Australian grayling, Prototroctes maraena Gnnther (Salmoniformes : Prototroctidae), in the Tambo River, Victoria

1983 ◽  
Vol 34 (3) ◽  
pp. 451 ◽  
Author(s):  
TM Berra ◽  
PL Cadwallader
Keyword(s):  
Age Determination ◽  
Fork Length ◽  
Age And Growth ◽  
Scale Growth ◽  
Length Frequency ◽  
Age Classes ◽  
Frequency Distributions ◽  
Overall Ratio ◽  
The Relationship ◽  
Australian Grayling

The age and growth of Australian grayling were studied in 1203 individuals collected from the Tambo River, Victoria, between January and November 1979. Scales from 667 grayling were examined. The scale method of age determination was validated by the analysis of seasonal changes in the pattern of scale growth and by correspondence between ages inferred from length-frequency distributions and ages determined by scale readings. One annulus is formed on the scale by October. Most (88%) grayling belonged to the 1+ and 2+ age-classes; fish aged 3+ and 4+ made up 11% of the collection, and fish aged 5+ less than 1%. Size increased from January until May; growth ceased during winter and resumed in September. There was no difference in growth between the sexes. The largest grayling collected was a female of 253 mm fork length (Lf). The overall length-weight relationship was W = 2 715 × 10-6Lf3 2764. The relationship between total length (Lt) and Lf was Lt = 0.93 16 + 1.0742 Lf, and between standard length (Ls) and Lf was Ls = 0.8007 + 0.9095 Lf The overall ratio of males to females was 56 : 44.

Digenean (Trematoda) populations in winter flounder (Pseudopleuronectes americanus) from Passamaquoddy Bay, New Brunswick, Canada

1985 ◽  
Vol 63 (7) ◽  
pp. 1699-1705 ◽  
Author(s):  
J. S. Scott
Keyword(s):  
New Brunswick ◽  
Alimentary Tract ◽  
Feeding Activity ◽  
The Body ◽  
Winter Flounder ◽  
Differential Migration ◽  
Pseudopleuronectes Americanus ◽  
Length Frequency ◽  
Frequency Distributions ◽  
Passamaquoddy Bay

Examination of monthly samples of winter flounder (Pseudopleuronectes americanus) from Passamaquoddy Bay revealed seven digenean parasites (Genolinea laticauda, Podocotyle atomon, Stenakron vetustum, Fellodistomum furcigerum, Derogenes varicus, Lecithaster gibbosus, and Steganoderma formosum) in the alimentary tract and two metacercariae (Stephanostomum baccatum and Cryptocotyle lingua) in the body surface tissues and gills. Prevalence of alimentary tract parasites ranged from 0.2 in S. formosum to 39.8 in P. atomon and intensity ranged from 1.5 for D. varicus to 7.0 for S. formosum (one fish). Monthly and seasonal levels of prevalence varied: high in spring and autumn and low in summer and winter for most species. Prevalence and length-frequency distributions of the parasites did not support differential migration by size group or diminishing feeding activity from spring to winter in winter flounder, as proposed in other studies.

Metacercarial distribution of Apophallus brevis (Heterophyidae) in yellow perch (Perca flavescens) from the Heming Lake study area

1983 ◽  
Vol 61 (9) ◽  
pp. 2104-2109 ◽  
Author(s):  
B. C. Poole ◽  
T. A. Dick
Keyword(s):  
Yellow Perch ◽  
Negative Binomial ◽  
Perca Flavescens ◽  
Open Water ◽  
The Body ◽  
Larus Argentatus ◽  
Fish Parasite ◽  
Age Classes ◽  
Species Identity ◽  
Parasite Populations

During a fish parasite survey in 1980 and 1981, 395 yellow perch (Perca flavescens) were removed from the Heming Lake study area (54°53′ N, 101°07′ W). Encysted Apophallus brevis metacercariae were found in the body musculature of perch from six lakes as well as the eye and body musculature of perch in Heming Lake. Species identity was confirmed with experimental infections in ring-billed (Larus delawarensis) and herring (Larus argentatus) gulls. No significant differences were found in prevalences or mean intensities of A. brevis metacercariae between male and female perch in Heming Lake. Prevalence levels remained high in most age-classes of Heming Lake perch and mean intensity differences were not significant for all ages beyond 1 year old. Slight variations from these Heming Lake results were found in other lakes. Prevalence levels of A. brevis in Heming Lake perch remained more or less constant during the open water seasons. Mean intensities dropped significantly from June to July and increased in August and October. Monthly fluctuations are probably the result of recruitment of the parasite and a loss of heavily infected hosts. The variance to mean ratios of A. brevis in perch from Heming, Home, and Demarch lakes showed that these parasite populations were overdispersed, and the distribution of each was found to fit the negative binomial. The authors question the use of variance to mean ratios or other statistics dealing with overdispersion in predicting loss or recruitment for all parasite systems.

scholarly journals Growth and population biology of the sand-bubbler crab Scopimera crabricauda Alcock 1900 (Brachyura: Dotillidae) from the Persian Gulf, Iran

2021 ◽  
Vol 82 (1) ◽  
Author(s):  
Sana Sharifian ◽  
Vahid Malekzadeh ◽  
Ehsan Kamrani ◽  
Mohsen Safaie
Keyword(s):  
Persian Gulf ◽  
Population Biology ◽  
Slow Growth ◽  
Carapace Width ◽  
Population Data ◽  
Natural Mortality ◽  
Frequency Distributions ◽  
Iranian Coast ◽  
The Mean ◽  
The Persian Gulf

Abstract Background Dotillid crabs are introduced as one common dwellers of sandy shores. We studied the ecology and growth of the sand bubbler crab Scopimera crabricauda Alcock, 1900, in the Persian Gulf, Iran. Crabs were sampled monthly by excavating nine quadrats at three intertidal levels during spring low tides from January 2016 to January 2017. Results Population data show unimodal size-frequency distributions in both sexes. The Von Bertalanffy function was calculated at CWt = 8.76 [1 − exp (− 0.56 (t + 0.39))], CWt = 7.90 [1 − exp (− 0.59 (t + 0.40))] and CWt = 9.35 [1 − exp (− 0.57 (t + 0.41))] for males, females, and both sexes, respectively. The life span appeared to be 5.35, 5.07, and 5.26 years for males, females, and both sexes, respectively. The cohorts were identified as two age continuous groups, with the mean model carapace width 5.39 and 7.11 mm for both sexes. The natural mortality (M) coefficients stood at 1.72 for males, 1.83 for females, and 1.76 years−1 for both sexes, respectively. The overall sex ratio (1:0.4) was significantly different from the expected 1:1 proportion with male-biased. Recruitment occurred with the highest number of annual pulse once a year during the summer. Conclusions The results, which show slow growth, emphasize the necessity of proper management for the survival of the stock of S. crabricauda on the Iranian coast of the Persian Gulf.

Reference points for the length-based indicator Lmax5% for use in the assessment of data-limited stocks

2019 ◽  
Vol 76 (7) ◽  
pp. 2125-2139 ◽  
Author(s):  
Tanja Miethe ◽  
Yves Reecht ◽  
Helen Dobby
Keyword(s):  
Life Histories ◽  
Stock Assessment ◽  
Reference Points ◽  
Length Frequency ◽  
Frequency Distributions ◽  
Simulation Tools ◽  
Spawning Potential Ratio ◽  
The Mean ◽  
Commercial Sources ◽  
Length Frequency Data

Abstract In the absence of abundance indices from scientific surveys or commercial sources, reliable length frequency data from sampled commercial catches can be used to provide an indirect assessment of fishing mortality. Length-based indicators are simple metrics which describe length frequency distributions. The length-based indicator Lmax5%, the mean length of the largest 5% of individuals in the catch, combined with appropriately selected reference points, can be used to evaluate the presence of very large individuals in the catch and hence determine exploitation level. Using analytical per-recruit models, we derive reference points consistent with a spawning potential ratio of 40%. The reference points depend on the life history parameters for natural mortality, maturity, and growth (M, Lmat, L∞, k, CVL∞). Using available simulation tools, we investigate the sensitivity of the reference points to errors in these parameters and explore the usefulness of particular reference points for management purposes for stocks with different life histories. The proposed reference points are robust to uncertainty in length at first capture, Lc, and take into account the maturation schedule of a species. For those stocks with high M/k ratios (>1), Lmax5%, combined with the appropriate reference point, can be used to provide a data-limited stock assessment.

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.

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