Dynamics of individual growth in a recovering population of lake trout (Salvelinus namaycush)

2001 ◽  
Vol 58 (2) ◽  
pp. 262-272 ◽  
Author(s):  
Mary C Fabrizio ◽  
Robert M Dorazio ◽  
Stephen T Schram
Keyword(s):  
Growth Rates ◽  
Lake Trout ◽  
Growth Dynamics ◽  
Salvelinus Namaycush ◽  
Wild Fish ◽  
Individual Growth ◽  
Wisconsin Department ◽  
Growth Increments ◽  
Before And After ◽  
The Mean

In 1976, the Wisconsin Department of Natural Resources established a refuge for a nearly depleted population of lake trout (Salvelinus namaycush) at Gull Island Shoal, Lake Superior. The refuge was intended to reduce fishing mortality by protecting adult lake trout. We examined the growth dynamics of these lake trout during the period of recovery by comparing estimates of individual growth before and after the refuge was established. Our estimates are based on an annual mark-recapture survey conducted at the spawning area since 1969. We developed a model that allowed mean growth rates to differ among individuals of different sizes and that accommodated variation in growth rates of individuals of the same size. Likelihood ratio tests were used to determine if the mean growth increments of lake trout changed after the refuge was established. Our results suggest that growth of mature lake trout (particularly wild fish) decreased significantly in the postrefuge period. This decreased growth may have been associated with a reduction in food availability. We also observed reductions in growth as wild fish grew older and larger, which suggests that the growth of these fish may be adequately approximated by a von Bertalanffy growth model if it becomes possible to obtain accurate ages.

Wintertime growth in Atlantic salmon under changing climate: the importance of ice cover for individual growth dynamics

2021 ◽  
Author(s):  
Laura Härkönen ◽  
Pauliina Louhi ◽  
Riina Huusko ◽  
Ari Huusko
Keyword(s):  
Climate Change ◽  
Atlantic Salmon ◽  
Growth Rates ◽  
Growth Dynamics ◽  
Ice Cover ◽  
Individual Growth ◽  
Late Winter ◽  
Dynamic Nature ◽  
Individual Level ◽  
Growth Variation

Understanding the dynamic nature of individual growth in stream-dwelling salmonids may help forecast consequences of climate change on northern fish populations. Here, we performed an experimental capture-mark-recapture study in Atlantic salmon to quantify factors influencing wintertime growth variation among juveniles under different scenarios for ice cover reduction. We applied multiple imputation to simulate missing size observations for unrecaptured fish, and to account for individual-level variation in growth rates. The salmon parr exhibited substantial body length shrinkage in early winter, suppressed growth through mid-winter, and increasing growth rates in late winter and particularly in spring. Unexpectedly, the presence of ice cover had no direct effects on wintertime growth. Instead, our results implied increasing energetic costs with reducing ice cover: individuals exposed to absent or shortened ice-covered period gained mass at a lowered rate in spring whereas the present, long ice-covered period was followed by rapid growth. This study emphasizes natural resilience of Atlantic salmon to wintertime environmental variation which may help the species to cope with the reductions in ice cover duration due to climate change.

Modeling data from double-tagging experiments to estimate heterogeneous rates of tag shedding in lake trout (Salvelinus namaycush)

1999 ◽  
Vol 56 (8) ◽  
pp. 1409-1419 ◽  
Author(s):  
Mary C Fabrizio ◽  
James D Nichols ◽  
James E Hines ◽  
Bruce L Swanson ◽  
Stephen T Schram
Keyword(s):  
Lake Trout ◽  
Survival Rates ◽  
Salvelinus Namaycush ◽  
Wild Fish ◽  
Retention Rates ◽  
Type I ◽  
Tag Retention ◽  
Tag Loss ◽  
Modeling Data ◽  
Tag Shedding

Data from mark-recapture studies are used to estimate population rates such as exploitation, survival, and growth. Many of these applications assume negligible tag loss, so tag shedding can be a significant problem. Various tag shedding models have been developed for use with data from double-tagging experiments, including models to estimate constant instantaneous rates, time-dependent rates, and type I and II shedding rates. In this study, we used conditional (on recaptures) multinomial models implemented using the program SURVIV (G.C. White. 1983. J. Wildl. Manage. 47: 716-728) to estimate tag shedding rates of lake trout (Salvelinus namaycush) and explore various potential sources of variation in these rates. We applied the models to data from several long-term double-tagging experiments with Lake Superior lake trout and estimated shedding rates for anchor tags in hatchery-reared and wild fish and for various tag types applied in these experiments. Estimates of annual tag retention rates for lake trout were fairly high (80-90%), but we found evidence (among wild fish only) that retention rates may be significantly lower in the first year due to type I losses. Annual retention rates for some tag types varied between male and female fish, but there was no consistent pattern across years. Our estimates of annual tag retention rates will be used in future studies of survival rates for these fish.

scholarly journals Growth Rate Variation and Larval Survival: Inferences from an Individual-Based Size-Dependent Predation Model

1993 ◽  
Vol 50 (1) ◽  
pp. 133-142 ◽  
Author(s):  
James A. Rice ◽  
Thomas J. Miller ◽  
Kenneth A. Rose ◽  
Larry B. Crowder ◽  
Elizabeth A. Marschall ◽  
...  
Keyword(s):  
Growth Rate ◽  
Growth Rates ◽  
Individual Variability ◽  
Individual Growth ◽  
Rate Variation ◽  
High Survival ◽  
Initial Growth ◽  
Size Dependent ◽  
The Mean ◽  
Selection For

We used an individual-based Monte Carlo simulation model to explore how changes in the mean and variance of growth rates of individuals in a larval fish cohort interact with size-dependent predation to affect the number and characteristics of individual survivors. Small changes in initial cohort mean growth rate can change survival over the first 60 d of life 10-to 30-fold. But when variance in growth rate among individuals is high, survival can be substantially higher than expected from the initial mean cohort growth rate. Selection for faster-growing individuals becomes stronger with increasing variance and increasing predation rate. In some cases, > 80% of the survivors may come from the upper 25% of the initial growth rate distribution, and the mean growth rate of the survivors may exceed twice the initial mean growth rate. When individual growth rates change from day to day rather than remaining constant, the contribution of atypical individuals is accentuated even further. Counterintuitively, most of the selection for faster-growing individuals happens only after the majority of mortality has already taken place. These results suggest that interactions between individual variability and selective mortality may have important cohort-level implications for survival in fishes.

A Simulation Model of Lake Trout Growth

1971 ◽  
Vol 28 (6) ◽  
pp. 815-819 ◽  
Author(s):  
S. R. Kerr
Keyword(s):  
Simulation Model ◽  
Growth Model ◽  
Lake Trout ◽  
Growth Efficiency ◽  
Equation System ◽  
Growth Increments ◽  
Predator Size ◽  
Mean Size ◽  
The Mean

Kerr (J. Fish. Res. Bd. Canada 28: 809–814, 1971) described an equation system based upon metabolic constraints and foraging limitations that predicts level of rations and growth efficiency as a function of the availability of the prey resource. An algorithm that extends the equation system to a growth model is described here. With reference to increasing predator size, and to the mean size and abundance of prey, the model computes successive growth increments while holding the equations to the configuration that maximizes the ratio of growth efficiency to rations. When given information on the mean size and density of prey organisms, the model accurately predicts observed patterns of lake trout growth.

Estimation of Recent Growth of Field-Caught Postlarval American Lobsters, Homarus americanus, from RNA:DNA Ratios

1994 ◽  
Vol 51 (2) ◽  
pp. 286-294 ◽  
Author(s):  
Marie Antonette R. Juinio ◽  
J. Stanley Cobb
Keyword(s):  
Growth Rates ◽  
Food Limitation ◽  
Homarus Americanus ◽  
Zooplankton Biomass ◽  
Individual Growth ◽  
Prolonged Duration ◽  
The Mean ◽  
Temperature And Growth ◽  
Relationship Of ◽  
The Relationship

We developed a growth model for the postlarvae of the American lobster, Homarus americanus, using the relationship of RNA:DNA ratios, temperature, and growth rates during postmolt through early pre-molt of laboratory-reared postlarval lobsters. The model was used to estimate individual growth rates of 385 postlarval lobsters in molt stages C and D0, collected at two sites in Block Island Sound over three years, 1988–90. The mean growth rates of postlarvae collected in June 1989 and 1990 (0.57 ± 0.19 and 0.54 ± 0.18 mg protein∙d−1) were significantly higher than those collected in July (0.39 ± 0.17 and 0.43 ± 0.18 mg protein∙d−1). Changes in sea surface temperatures of zooplankton biomass did not account for the seasonal difference in growth rates, nor was there correlation between the biweekly mean growth rates and postlarval densities. The incidence of poorly nourished postlarval lobsters (individuals with growth rates < 0.22 mg protein∙d−1) was less than 10% of the total samples in each year. We found no evidence that food limitation, resulting in starvation or prolonged duration of the postlarval instar, was a significant factor contributing to the observed interannual variability of postlarval densities.

Recovery of Planted Brook Trout, Splake, and Rainbow Trout from Selected Ontario Lakes

1972 ◽  
Vol 29 (2) ◽  
pp. 129-142 ◽  
Author(s):  
J. M. Fraser
Keyword(s):  
Rainbow Trout ◽  
Brook Trout ◽  
Fish Community ◽  
Lake Trout ◽  
Salvelinus Namaycush ◽  
Low Fertility ◽  
Salmo Gairdneri ◽  
White Sucker ◽  
The Mean ◽  
Brook Stickleback

Recoveries of hatchery-reared brook trout (Salvelinus fontinalis), splake (Salvelinus namaycush × S. fontinalis), and rainbow trout (Salmo gairdneri), planted in lakes having different resident fishes, were highest (9–30%) in a lake in which minnows and the brook stickleback were the only other fishes. Recoveries, by angling and gillnetting, were considerably lower (2–15%) in two lakes containing the white sucker and minnows, and still lower (0.5–5%,) in two lakes containing spiny-rayed species as well. Recoveries were lowest (< 0.5%) in a lake having a complex fish community that included native brook and lake trout. Planted splake and rainbow trout generally yielded higher returns, in weight, than brook trout in comparable situations.The low survival of planted fish was apparently due to the low fertility of the waters and to competition with, or predation by, resident fish species. Predation by fish-eating birds and mammals may also have had an effect.The weight of the catch of salmonids exceeded the weight planted in only one lake. Here, the mean yield of planted salmonids was 8.4 kg/ha per year in comparison with 2.6 to < 0.5 kg/ha per year in the five other study lakes.

scholarly journals Chryseobacterium aahli sp. nov., isolated from lake trout (Salvelinus namaycush) and brown trout (Salmo trutta), and emended descriptions of Chryseobacterium ginsenosidimutans and Chryseobacterium gregarium

2014 ◽  
Vol 64 (Pt_5) ◽  
pp. 1573-1579 ◽  
Author(s):  
Thomas P. Loch ◽  
Mohamed Faisal
Keyword(s):  
Brown Trout ◽  
Salmo Trutta ◽  
Type Species ◽  
Lake Trout ◽  
Phylogenetic Analyses ◽  
Salvelinus Namaycush ◽  
Rrna Gene ◽  
Content Type ◽  
Link Type ◽  
The Mean

Two strains (T68T and T62) of a Gram-reaction-negative, yellow-pigmented bacterium containing flexirubin-type pigments were recovered from the kidney of a cultured lake trout (Salvelinus namaycush) and necrotic fins of a brown trout (Salmo trutta) during disease surveillance in 2009. Both isolates possessed catalase and cytochrome oxidase activities and degraded multiple substrates (e.g. gelatin, casein, elastin and Tweens 20 and 80). The mean DNA G+C content of strain T68T was 34.1 mol%. 16S rRNA gene sequencing demonstrated that strains T68T and T62 had nearly identical sequences (≥99 % similarity) and placed the bacterium within the genus Chryseobacterium , where Chryseobacterium ginsenosidimutans THG 15T (97.8 %), C. gregarium DSM 19109T (97.7 %) and C. soldanellicola PSD1-4T (97.6 %) were its closest relatives. Subsequent phylogenetic analyses using neighbour-joining, maximum-parsimony and Bayesian methodologies demonstrated that strains T68T and T62 formed a well-supported clade (bootstrap values of 100 and 97 %; posterior probability 0.99) that was distinct from other species of the genus Chryseobacterium . The major fatty acids of strains T68T and T62 were characteristic of the genus Chryseobacterium and included iso-C15 : 0, summed feature 3 (C16 : 1ω6c and/or C16 : 1ω7c), iso-C17 : 0 3-OH, C16 : 0 and C16 : 0 3-OH. The mean DNA–DNA relatedness of strain T68T to C. ginsenosidimutans JCM 16719T and C. gregarium LMG 24952T was 24 and 21 %, respectively. Based on the results from our polyphasic characterization, strains T68T and T62 represent a novel species of the genus Chryseobacterium , for which the name Chryseobacterium aahli sp. nov. is proposed. The type strain is T68T ( = LMG 27338T = ATCC BAA-2540T). Emended descriptions of Chryseobacterium ginsenosidimutans and Chryseobacterium gregarium are also proposed.

scholarly journals Kinetic evaluation of low-grade gliomas in adults before and after treatment with CCNU alone

2015 ◽  
Vol 123 (5) ◽  
pp. 1244-1246 ◽  
Author(s):  
Gentian Kaloshi ◽  
Ermir Roci ◽  
Arben Rroji ◽  
Francois Ducray ◽  
Mentor Petrela
Keyword(s):  
Single Agent ◽  
Growth Dynamics ◽  
Low Grade ◽  
Tumor Diameter ◽  
Astrocytic Tumors ◽  
Kinetic Evaluation ◽  
Oligodendroglial Tumors ◽  
Before And After ◽  
The Mean ◽  
The Impact

OBJECT The aim of this study was to evaluate the impact of CCNU chemotherapy alone on low-grade glioma (LGG) growth dynamics. METHODS The authors measured the evolution of the mean tumor diameter (MTD) in adult patients with LGG before (n = 28 patients) and after (n = 38 patients) CCNU administration. RESULTS Natural (spontaneous) growth of LGG in the present study was 4.3 mm/year (range 2.1–6.6 mm/year). The median MTD decrease after CCNU was 5.1 mm/year (range 1–8.9 mm/year). MTD decrease was noted in 30 patients (late decrease in 4 patients, and ongoing decrease in 24 patients with oligodendroglial tumors and 2 with astrocytic tumors). The median duration it took for the MTD to decrease after initiation of CCNU treatment was 619 days (1038 days for oligodendroglial tumors vs 377 days for astrocytic tumors; p = 0.003). CONCLUSIONS These results show that CCNU as a single agent has a significant impact on LGG tumor growth. The impact of CCNU seems to be comparable to the previously reported impact of temozolomide therapy and of combined procarbazine, CCNU, and vincristine chemotherapy.

Survival of Marked Lake Trout in Lake Manitou, Manitoulin Island, Ontario

1968 ◽  
Vol 25 (11) ◽  
pp. 2257-2268 ◽  
Author(s):  
J. C. Budd ◽  
F. E. J. Fry ◽  
J. B. Smith
Keyword(s):  
Mortality Rate ◽  
Lake Trout ◽  
Sea Lamprey ◽  
Salvelinus Namaycush ◽  
Total Plant ◽  
The Mean ◽  
Annual Mortality

Lake trout (491 in all), Salvelinus namaycush, planted as yearlings in Lake Manitou in 1952 were tagged at age VII when taken in trap nets during spawntaking operations. At the same time 259 native adult trout of unknown age were also tagged. In spawntaking operations in subsequent years tag numbers were noted for tagged fish recaptured and the fish returned to the lake after normal spawntaking. Both groups were estimated to have suffered a decrement of 25% per year. The lake trout planted were given a distinctive fin clip on planting so that comparisons of recaptures of tagged and untagged planted fish permitted estimates of the survival of the total plant. The mean annual mortality rate from the time of planting was also estimated at 25%. Trout planted later appeared to have suffered a similar mortality rate. Observations on planted lake trout of known age indicated that the peak age for first spawning in females was age VI. There is no predation by sea lamprey in Lake Manitou.

Growth rates of juvenile southern rock lobster (Jasus edwardsii) estimated through a diver-based tag - recapture program

2012 ◽  
Vol 63 (2) ◽  
pp. 110 ◽  
Author(s):  
Adrian Linnane ◽  
David Hobday ◽  
Stewart Frusher ◽  
Caleb Gardner
Keyword(s):  
Growth Rates ◽  
South Australia ◽  
Individual Growth ◽  
Rock Lobster ◽  
South Eastern ◽  
Growth Increments ◽  
Eastern Australia ◽  
Significant Difference ◽  
Jasus Edwardsii ◽  
South Eastern Australia

Despite being one of the most economically important fisheries in south-eastern Australia, growth rates of juvenile southern rock lobster (Jasus edwardsii) have not previously been quantified in the wild. This study utilised a diver-based tag–recapture program to estimate growth rates of individuals between 40–80 mm carapace length (CL) in temperate reef sites across south-eastern Australia. Of the 7064 lobsters tagged and released, 978 (14%) were recaptured with recapture rates of 23, 5 and 7% in the States of Tasmania, South Australia and Victoria respectively. Although individual growth increments were similar between the sexes, differences in annual growth rates were evident at 50 mm CL, with males growing ~1.4 times faster than females. Increased levels of growth in males resulted from a higher moult frequency, which was found to significantly reduce in females as they reached sexual maturity at ~70–80 mm CL. No significant difference was found in growth rates of males or females between the States when all sites within each State were combined. The growth estimates from this work contribute to the understanding of juvenile lobster population dynamics and will improve current fishery models by confirming relationships between early juvenile, pre-recruit abundance and entry to the fishable biomass.

Sign in / Sign up

Export Citation Format

Share Document