scholarly journals Changes in baseline growth and maturation parameters of Northwest Atlantic porbeagle, Lamna nasus, following heavy exploitation

2007 ◽  
Vol 64 (1) ◽  
pp. 19-29 ◽  
Author(s):  
Rachel M Cassoff ◽  
Steven E Campana ◽  
Sigmund Myklevoll
Keyword(s):  
Growth Rate ◽  
Growth Response ◽  
Growth Models ◽  
Fork Length ◽  
Likelihood Ratio Tests ◽  
Age At Maturity ◽  
Northwest Atlantic ◽  
Density Dependent ◽  
Growth Changes ◽  
Dependent Growth

We tested for density-dependent changes in growth and maturation of Northwest Atlantic porbeagle (Lamna nasus) after the population declined by 75%–80% from fishing. Vertebrae and reproductive data collected from the virgin (1961–1966) and exploited (1993–2004) populations were analysed to test for differences in growth rate and age and length at maturity between the time periods. We detected significant differences between reparameterized von Bertalanffy growth models for each period, using likelihood ratio tests. Beyond an age of 7 years, mean length at age was greater during 1993–2004 than during 1961–1966. Between 1961–1963 and 1999–2001, length at maturity decreased in males (from 179 to 174 cm curved fork length (CFL)) and was invariant in females (216 cm CFL), whereas age at maturity declined in both males (from 8 to 7 years) and females (from 19 to 14 years). An analysis of porbeagle temperature associations indicated that sharks occupied comparable temperature conditions during the mid-1960s and 1990s, ruling out the possibility of temperature-induced growth changes. The observed increase in growth rate and decrease in age at maturity following exploitation support the hypothesis of a compensatory density-dependent growth response.

scholarly journals Age and growth of redfish (Sebastes marinus, S. mentella, and S. fasciatus) on the Flemish Cap (Northwest Atlantic)

2004 ◽  
Vol 61 (2) ◽  
pp. 231-242 ◽  
Author(s):  
Fran Saborido-Rey ◽  
Dolores Garabana ◽  
Santiago Cerviño
Keyword(s):  
Growth Rate ◽  
Density Dependence ◽  
Slow Rate ◽  
Age Determination ◽  
Age And Growth ◽  
Northwest Atlantic ◽  
Density Dependent ◽  
Dependent Growth ◽  
Sebastes Mentella

Abstract Age determination of redfish is difficult. In this paper, the ages of Sebastes mentella on the Flemish Cap are validated by following year classes from 1991 to 2000. The criteria used for S. mentella are consistent and coherent. The growth of different year classes is described and compared, and density-dependence is demonstrated to influence the growth rate of the strong 1990 year class, growth of that year class being the slowest of those followed. The slow rate of growth prevented that year class from maturing at the anticipated age. Growth is also compared between sexes, of S. mentella, S. marinus, and S. fasciatus, revealing that females grow faster than males. Finally, growth rate is compared among species. S. marinus grows fastest and S. mentella slowest, although the influence of density-dependent growth in S. mentella needs to be taken into consideration.

Density-Dependent Growth Adaptation Kinetics in 3T 3 Cell Populations Following Sudden [Ca2+] and Temperature Changes. A Comparison with SV40-3T3 Cells

1979 ◽  
Vol 34 (3-4) ◽  
pp. 279-283 ◽  
Author(s):  
Jürgen van der Bosch ◽  
Ilse Sommer ◽  
Heinz Maier ◽  
Willy Rahmig
Keyword(s):  
Growth Rate ◽  
Cell Density ◽  
Cell Number ◽  
Cell Populations ◽  
3T3 Cells ◽  
Density Dependent ◽  
Cell Densities ◽  
Dependent Growth ◽  
Growth Adaptation ◽  
Stationary Cell

Abstract Lowered extracellular [Ca2+] causes low growth rates and low stationary cell densities in 3T3 cell cultures as compared to physiological [Ca2+]. Under otherwise constant conditions the extra­ cellular [Ca2+] determines a stable stationary cell density, which can be readied by increase of net cell number or decrease of net cell number, depending on cell density at the time of [Ca2+] adjustment. SV40-3T3 cells do not show this [Ca2+] dependency. At 39 °C 3T3 and SV40-3T3 cell populations show an increased growth rate at low cell densities as compared to cell populations at 35 °C. Approaching the stationary density the growth rate of both cell sorts is reduced faster at 39 °C than at 35 °C, leading to lower stationary cell densities at 39 °C than at 35 °C. A temperature change from 39 °C to 35 °C or in the opposite direction can affect the stationary cell density of 3T3 cell populations only if applied before reduction of growth rate by density-dependent growth-inhibiting principles has taken place.

Genetic influence of parr versus anadromous sires on the life histories of Atlantic salmon (Salmo salar)

2005 ◽  
Vol 62 (9) ◽  
pp. 2067-2075 ◽  
Author(s):  
J Duston ◽  
T Astatkie ◽  
P F MacIsaac
Keyword(s):  
Salmo Salar ◽  
Repeated Measures ◽  
Life Histories ◽  
Sexual Maturity ◽  
Condition Factor ◽  
Fork Length ◽  
Age At Maturity ◽  
Repeated Measures Analysis ◽  
Life History Patterns ◽  
Growth Changes

The potential for sire size to influence life history patterns from fry to sea age at maturity was established by rearing individually identified half-sibs of a single dam and either small (parr) or large (anadromous) sires in a common tank environment. Male sexual maturity was higher among progeny of small versus large sires at both parr (age 0+, 50% versus 32%, p = 0.065) and grilse stages (age 2+, 23% versus 10%, p = 0.034). In contrast, rates of female grilse (6.8%) and smolt age 1+ (>95%) were independent of sire size. Logistic regression indicated that grilse of small sires had an asymptote body weight (BW) 30% lower than grilse of large sires (1.0 versus 1.4 kg). In comparison, repeated measures analysis of BW, fork length (FL), and condition factor (CF) indicated that growth changes associated with grilsing were independent of sire size and sex. The highest-order interaction for which sire size was significant was day × sire × sex (p < 0.034). Independent of sire size, sexual maturation at both age 0+ and age 2+ was associated with a high CF, whereas smolting at age 1+ was associated with a high BW and FL but low CF.

Empirical Size-Dependent Growth Rate Models

1992 ◽  
Vol 57 (2) ◽  
pp. 309-325 ◽  
Author(s):  
Jerzy Mydlarz
Keyword(s):  
Growth Rate ◽  
Crystal Size ◽  
Size Range ◽  
Growth Models ◽  
Crystal Growth Rate ◽  
Size Distributions ◽  
Large Crystal ◽  
Size Dependent ◽  
Dependent Growth ◽  
Empirical Size

A comparison of well known size-dependent crystal growth rate models has been presented. The models have been verified for crystal size distributions which have been recently presented in the literature. It is shown that for large crystal size range both the Abegg-Stevenson-Larson (ASL) model and the Canning-Randolph (C-R) model can be reduced to the simplest Bransom model. Two another kinetics size-dependent growth rate models have been presented and tested for size distributions which were recently presented by Mydlarz and Jones. Application of the proposed size-dependent growth models gives much better estimation of growth rate than other size-dependent models tested as well as Sikdar and White-Bendig-Larson methods.

scholarly journals Dispersal and density-dependent growth of Atlantic salmon (Salmo salar) juveniles: clumped versus dispersed stocking

2017 ◽  
Vol 74 (9) ◽  
pp. 1337-1347 ◽  
Author(s):  
Eric Blake Brunsdon ◽  
Dylan John Fraser ◽  
William Rundle Ardren ◽  
James William Angus Grant
Keyword(s):  
Growth Rate ◽  
Atlantic Salmon ◽  
Salmo Salar ◽  
Negative Power ◽  
Growth And Survival ◽  
Density Dependent ◽  
Atlantic Salmon Salmo Salar ◽  
Nesting Sites ◽  
Juvenile Habitat ◽  
Dependent Growth

Dispersal from nesting sites and habitat selection are essential for the fitness of young individuals and shape the distribution, growth, and persistence of populations. These processes are important to consider when releasing young, hatchery-origin fishes into the wild to restore extirpated or depleted populations. By manipulating the density of released young-of-the-year (YOY) Atlantic salmon (Salmo salar), we evaluated the effects of clumped- (releasing all the fish at one location) and dispersed-stocking (releasing the fish evenly over a complete reach) treatments on juvenile habitat use, dispersal, growth, and survival. Across 14 river reaches, clump-stocked YOY density decreased and growth rate increased with distance downstream, whereas dispersed-stocked YOY densities and growth were relatively constant. Overall, density, spatial variance in density, growth, and survival did not differ between these two stocking treatments, likely due to the greater-than-expected mobility of fish in clumped-stocking reaches; YOY dispersed up to 1600 m, with 41% moving over 200 m downstream. As predicted from previous work, growth rate of individual fish was density-dependent, following a negative power curve. Our results provide insights into how the growth and survival of released individuals are altered via stocking treatments, ultimately shaping their distribution and growth rate.

Maintenance and breakdown of the Hydra–Chlorella symbiosis: a computer model

1989 ◽  
Vol 238 (1292) ◽  
pp. 277-289 ◽  
Keyword(s):  
Growth Rate ◽  
Cell Growth ◽  
Host Cell ◽  
Computer Model ◽  
Inorganic Nutrients ◽  
Cell Growth Rate ◽  
Digestive Cells ◽  
Density Dependent ◽  
Dissolved Inorganic Nutrients ◽  
Dependent Growth

To understand the mechanism by which dissolved inorganic nutrients cause Chlorella to overgrow Hydra digestive cells, the symbiosis between hydra ( Hydra viridissima ) and algae ( Chlorella sp.) was simulated with a novel computer model. The model faithfully simulates the attainment of equilibrium populations of algae and hydra digestive cells, as well as overgrowth by algae. The model is used to discern the parameters that lead to instability of the symbiosis. Additional simulations suggest that several mechanisms acting together are required to produce overgrowth. These include the release of algae from density-dependent growth, entrance of an increased proportion of algae into division, division of an increase proportion of these into eight autospores, and a decrease in the host cell growth rate.

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