Studies on southern Australian Abalone (Genus Haliotis). VIII. Growth of juvenile H. laevigata

1988 ◽  
Vol 39 (2) ◽  
pp. 177 ◽  
Author(s):  
SA Shepherd
Keyword(s):  
Growth Rate ◽  
South Australia ◽  
Length Frequency ◽  
Frequency Distributions ◽  
The Mean

The growth of juvenile H. laevigata was studied by analysis of sequences of length-frequency distributions obtained in below- and above-boulder habitats at West Island, South Australia. The mean growth rate overall is 1.69 mm month-1 and is linear with length for the first 5 years, but thereafter declines with increasing length. The mean growth rate of four groups of marked H. laevigata aged 1 and 3 years is 1.6-2.1 mm month-1, and thus supports the estimation of growth rate from analysis of length-frequency distributions.

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.

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.

Studies on southern Australian abalone (Genus Haliotis). IV. Growth of H. laevigata and H. ruber

1983 ◽  
Vol 34 (3) ◽  
pp. 461 ◽  
Author(s):  
SA Shepherd ◽  
WS Hearn
Keyword(s):  
Growth Rate ◽  
Average Rate ◽  
South Australia ◽  
Annual Growth ◽  
First Year ◽  
Growth Equation ◽  
Annual Growth Rate ◽  
Growth Data ◽  
Differential Growth ◽  
Frequency Distributions

The growth of H. laevigata Donovan and H. ruber Leach was studied at several sites in South Australia by fitting the von Bertalanffy growth equation to growth data, supplemented by analysis of length- frequency distributions. Juvenile individuals of H. laevigata grow at an average rate of 0.9 mm per week, reaching a length of about 40 mm in 1 year at West Island; at Waterloo Bay H. laevigata can reach a length of 50 mm in the first year. After the first year, the annual growth coefficient (K) and the asymptotic length (L∞) for the two species at three sites are, respectively: H. laevigata-0.48 year-1 and 138 mm (West I.); 0.41 year-1 and 131 mm (Tipara Reef); 0.59 year-1 and 148 mm (Waterloo Bay); H, ruber-0 34 year-1 and 139 mm (West I.); 0.32 year-1 and 143 mm (Tipara Reef); 0 41 year-1 and 144 mm (Waterloo Bay). There are also seasonal differences in growth rate between species and between sites. These differences as well as differences in the annual growth rate within a species between sites are associated predominantly with differences in the food supply. There is differential growth between the sexes of H. laevigata at Waterloo Bay, where females grow 25% faster than males and reach a larger size.

Larval Flatfish Distributions and Drift on the Southern Grand Bank

1992 ◽  
Vol 49 (3) ◽  
pp. 467-483 ◽  
Author(s):  
Kenneth T. Frank ◽  
John W. Loder ◽  
James E. Carscadden ◽  
William C Leggett ◽  
Christopher T. Taggart
Keyword(s):  
Growth Rate ◽  
Thermocline Depth ◽  
Length Frequency ◽  
Frequency Distributions ◽  
Yellowtail Flounder ◽  
Limanda Ferruginea ◽  
Larval Drift ◽  
Vertical Distributions ◽  
Hippoglossoides Platessoides ◽  
Rule Out

Ichthyoplankton and hydrographic surveys of the southern Grand Bank in September of 1986, 1987, and 1988 revealed substantial correspondence between the areal distributions of larvae of three flatfish species and temperature below the thermocline. Depth-averaged densities of American plaice (Hippoglossoides platessoides) were negatively correlated with temperature whereas yellowtail flounder (Limanda ferruginea) and witch flounder (Glyptocephalus cynoghssus) densities were positively correlated with temperature. In spite of large interannual differences in abundance, the larval distributions showed similar structure from year to year. Using estimates of larval age inferred from length frequency distributions and literature values for growth rate, in conjunction with moored current measurements, estimates of spawning times and locations were obtained for each species. These estimates were compared with historical information on the distribution of prespawning fish for each species to examine the hypothesis of passive larval drift. The results indicate that in most, but not all cases, the larval distributions and currents are consistent with passive larval drift for particular growth rates and vertical distributions. However, the observations are not adequate to rule out alternative mechanisms involving behaviour.

scholarly journals Abundance, seasonality and size of Atlantic salmon smolts entrained on power station intake screens in the Severn Estuary

1994 ◽  
Vol 74 (3) ◽  
pp. 527-534 ◽  
Author(s):  
P.N. Claridge ◽  
I.C. Potter
Keyword(s):  
Atlantic Salmon ◽  
Standard Length ◽  
Condition Factor ◽  
Early Summer ◽  
Length Frequency ◽  
Power Station ◽  
Severn Estuary ◽  
Frequency Distributions ◽  
The Mean ◽  
One Year

Atlantic salmon smolts were sampled from the intake screens of the Oldbury power station in the inner Severn Estuary at weekly intervals between July 1972 and June 1977. These catches, and those taken over nearly three years from the nearby Berkeley power station, demonstrated that the abundance of smolts in the estuary peaked in autumn (October) and, to a far greater extent, in spring (April and May). However, small numbers of smolts were occasionally found in all other months of the year except July. Standard length-frequency distributions of smolts remained unimodal throughout the year. Lengths ranged from 76 to 187 mm, mean 130·2 ±1·87 mm (95% CL), and wet weights ranged from 5·4 to 68·0 g, mean 26·9 ±1·17 g. The mean monthly standard length of smolts increased slightly between the autumn of one year and the spring/early summer of the next year, suggesting that, on average, the former were six months younger than the latter. The condition factor was significantly greater in autumn (1·40) than in spring (1·23). It is estimated that the total number of salmon smolts entrained annually on the screens at Oldbury during the five years ranged from 92 to 791, with a mean of 405. Total estimated numbers at Berkeley ranged from 196 to 788 per annum. The numbers at Oldbury are lower than those estimated for the downstream migrants of the Twaite shad, another anadromous species, and far lower than those of the most abundant of the marine fish species that use the Severn Estuary as a nursery area.

Inferring the Summer Distribution of Migratory Pacific Hake (Merluccius productus) from Latitudinal Variation in Mean Lengths-at-Age and Length Frequency Distributions

1992 ◽  
Vol 49 (4) ◽  
pp. 708-721 ◽  
Author(s):  
Barry D. Smith ◽  
Gordon A. McFarlane ◽  
Mark W. Saunders
Keyword(s):  
Fish Population ◽  
Vancouver Island ◽  
Length Frequency ◽  
Frequency Distributions ◽  
Merluccius Productus ◽  
The Mean ◽  
Summer Distribution ◽  
The Right ◽  
Mean Variance ◽  
Length Frequency Data

Average summer distribution of abundance and biomass for the migratory population of Pacific hake (Merluccius productus) is described by age, length, and latitude, based on a model proposing that (1) changes in mean length-at-age with latitude and (2) the nonnormal (skewed to the right) appearance of length-at-age distributions near southwest Vancouver Island could be caused by length-dependent migration velocities and changing migration velocity with latitude. Our model uses mean length-at-age data collected annually near four latitudes from California to Vancouver Island, length frequency data collected annually near southern Vancouver Island from 1978 until 1988, and hydroacoustic data collected triennialiy from 1977 until 1986. We conclude that (1) hake slow their northward migration from the spawning grounds off southern California as they approach the productive feeding grounds off southwestern Vancouver Island, (2) older (larger) hake migrate further north than younger (smaller) hake, and (3) older hake are more abundant in Canadian waters than younger hake. Although all three conclusions have previously been partly substantiated, we show that seemingly undramatic patterns in the mean, variance, and distribution of lengths-at-age can be remarkably revealing about the distribution of a migrating fish population.

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.

The Age Structure and Growth Dynamics of Young-Of-The-Year Bass, Dicentrarchus Labrax, Populations

1991 ◽  
Vol 71 (4) ◽  
pp. 799-810 ◽  
Author(s):  
S. Jennings ◽  
J. E. Lancaster ◽  
J. S. Ryland ◽  
S. E. Shackley
Keyword(s):  
Growth Rate ◽  
Growth Rates ◽  
Dicentrarchus Labrax ◽  
Growth Dynamics ◽  
Frequency Distributions ◽  
South Wales ◽  
Nursery Habitats ◽  
The Mean ◽  
Young Of The Year ◽  
Time Of Year

Back-calculated egg fertilization (spawned) dates and growth rates for young-of-the-year bass, Dicentrarchus labrax (L), captured from Loughor Estuary, Oxwich Bay and Ogmore Estuary, south Wales, UK, during 1988 and 1989 were compared. Spawned date frequency distributions indicated that the bass spawning season began in late February and continued until early June in 1988 and early July in 1989.There were no significant differences in the frequency distributions of back-calculated spawned dates for the bass populations, between either sites or years, which suggested that any variations in growth rates were attributable to characteristics of their respective environments. Growth rates were determined for bass cohorts resulting from early, midor late-season spawnings at Oxwich and Loughor in 1988 and Oxwich, Loughor and Ogmore in 1989. There were only slight intra-annual differences between the mean growth rates of bass cohorts at the same site, suggesting that bass from early cohorts would be larger at any given time of year. In 1989, growth was considerably faster at Oxwich and Loughor than at Ogmore, where food supply was considered limiting. However, between-site variations in growth rate were small in comparison with inter-annual differences. The faster growth rates observed at Loughor and Oxwich in 1989 were attributed to higher water temperatures.Relationships between growth rate and subsequent survival of young-of-the-year bass, and the relative importance of estuaries as nursery habitats for juvenile bass, are discussed.

Ontogenetic Development of Growth Rates in Larval Pacific Herrings, Clupea harengus pallasi, Measured with RNA–DNA Ratios in the Strait of Georgia, British Columbia

1988 ◽  
Vol 45 (8) ◽  
pp. 1422-1429 ◽  
Author(s):  
S. M. C. Robinson ◽  
D. M. Ware
Keyword(s):  
Growth Rate ◽  
Growth Rates ◽  
Clupea Harengus ◽  
Critical Ratio ◽  
Strait Of Georgia ◽  
Frequency Distributions ◽  
Clupea Harengus Pallasi ◽  
In Captivity ◽  
The Mean ◽  
Mass Starvation

During the spring of 1986, a cohort of Pacific herring, Clupea harengus pallasi, larvae was sampled for 36 d in the Strait of Georgia to measure growth rates using RNA–DNA ratios for individual larvae. Concurrent with the field study, a population of herring larvae was starved from hatching in captivity for comparison with those caught in the field. The mean RNA–DNA ratio at hatching for the starved larvae was close to 2 but it quickly rose to 3.4 by age 4 d. The mean RNA–DNA ratio subsequently dropped back to 2 and below by age 8 d, presumably reflecting the exhaustion of the endogenous food supply of the yolk sac. The mean RNA–DNA ratio at the calculated point-of-no-return was 2.06 which was very similar to the zero protein growth rate or what we define as the "critical ratio." Herring larvae from the field generally showed an increase in the RNA–DNA ratio over the 36 d from approximately 2 to 7 although the first 18 d showed more variation than the latter. There was no evidence of mass starvation ("critical period") for the 1986 year class but there was a noticeable drop in the growth rate during the change to exogenous feeding. We suggest that starvation probably only directly affected the developing larvae during a window of about 11 d. Frequency distributions of the RNA–DNA ratios are shown for larvae over time.

The incidence of central serous chorioretinopathy in the population of Kazan: Results of a retrospective epidemiological analysis for 2009–2018

2020 ◽  
pp. 30-33
Author(s):  
D. R. Аgliullin ◽  
G. R. Khasanova ◽  
E. A. Abdulaeva ◽  
S. T. Agliullina ◽  
A. N. Amirov ◽  
...  
Keyword(s):  
Growth Rate ◽  
Central Serous Chorioretinopathy ◽  
Morbidity Rate ◽  
Seasonal Prevalence ◽  
Upward Trend ◽  
Epidemiological Analysis ◽  
Significant Upward Trend ◽  
Track Record ◽  
Minimum Age ◽  
The Mean

Objective: To assess the incidence of central serous chorioretinopathy (CSC) through the example of a large industrial Russian city.Methods: A retrospective analysis of CSC of Kazan population for 2009–2018 has been done.Results: From 2019 to 2018, 831 new cases of CSC were registered in Kazan. A statistically significant upward trend with growth rate 105.2% and accession rate 5.2% was typical for the annual track record. The mean age of patients was 50 years, the minimum age was 14 years, the maximum age was 87 years. A statistically significant upward trend was detected in track record of incidence in groups of 30–39-year-old and 40–49-year-old. Seasonal increase of the incidence was recorded in February, March, April, October, and November.Conclusions: The upward trend and seasonal prevalence are typical for longterm morbidity of CSC in Kazan. The highest morbidity rate of CSC and statistically significant upward trend of its incidence in track record were recorded in the age of 30–39. 

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