scholarly journals Trends in the size and age structure of marine fishes

2018 ◽  
Vol 76 (4) ◽  
pp. 938-945 ◽  
Author(s):  
Julie A Charbonneau ◽  
David M Keith ◽  
Jeffrey A Hutchings
Keyword(s):  
Age Structure ◽  
Population Viability ◽  
Marine Fishes ◽  
Adult Survival ◽  
Average Weight ◽  
Fish Stocks ◽  
Size And Age Structure ◽  
Spawning Behaviour ◽  
The Mean

Abstract Size-selective harvesting is expected to reduce the average age and weight of commercially exploited fishes. The loss of larger, older fish has been hypothesized to negatively affect metrics of population viability, such as spawning behaviour, recruitment, and adult survival. Most studies to date have focussed on individual stocks. Here, we examine trends in average age and weight at broad taxonomic and temporal scales, using subsets of data compiled on 95 marine fish stocks. Following moderate declines between 1960 and 1990, we find that the average age has generally increased since 2000, such that 71% of 69 stocks are currently above their long-term average. However, the size of the oldest individuals has generally declined over time; the average weight is currently below average in 75% of 55 stocks. A temporal decline in the mean weight of the youngest constituents within 49 stocks is most evident in the Clupeiformes. Our results indicate that recovery of age structure need not be accompanied by recovery of weights-at-age, evidenced in part by a decline in the size of the oldest individuals within populations. Further study into the drivers of these patterns, and the consequences of declining weights-at-age for population viability, is warranted.

scholarly journals Impacts of survival and reproductive success on the long-term population viability of reintroduced great bustards Otis tarda in the UK

Oryx ◽  
2015 ◽  
Vol 50 (4) ◽  
pp. 583-592 ◽  
Author(s):  
Kate Ashbrook ◽  
Andrew Taylor ◽  
Louise Jane ◽  
Ian Carter ◽  
Tamás Székely
Keyword(s):  
Habitat Management ◽  
Bird Species ◽  
Population Viability ◽  
Adult Survival ◽  
Wild Populations ◽  
Great Bustard ◽  
Otis Tarda ◽  
Demographic Rates ◽  
The Uk

AbstractReintroductions aim to re-establish species within their historical ranges through the release of wild- or captive-bred individuals following extirpation (or extinction) in the wild. There is no general agreement on what constitutes a successful reintroduction but the probability of the population achieving long-term persistence should be addressed. Here we review a 10-year trial reintroduction of the great bustard Otis tarda, a globally threatened bird species, to the UK and assess the long-term population viability. Despite changes in rearing and release strategy, initial post-release survival probability remained consistently low, with only 11.3% of bustards (n = 167) surviving from release to 1 year post-release. Nineteen breeding attempts were made by eight females; however, only one chick survived > 100 days after hatching, and no wild juveniles have recruited into the population. Using demographic rates from the UK population and wild populations elsewhere, and stochastic population modelling, we investigate the viability of this reintroduced population by predicting population size over the next 10 years. Under current demographic rates the population was predicted to decline rapidly. Self-sufficiency was predicted only using the highest estimates from the UK population for first-year and adult survival, and recruitment rates from wild populations elsewhere. Although changes have been made in rearing, release strategies, habitat management and release sites used, these changes appear to have a modest effect on long-term viability. Substantial improvements in survival rates and productivity are necessary to establish a viable great bustard population in the UK, and we consider this unlikely.

Pronounced long-term juvenation in the spawning stock of Arcto-Norwegian cod (Gadus morhua) and possible consequences for recruitment

2008 ◽  
Vol 65 (3) ◽  
pp. 523-534 ◽  
Author(s):  
Geir Ottersen
Keyword(s):  
Time Series ◽  
Gadus Morhua ◽  
Experimental Studies ◽  
Reproductive Capacity ◽  
Fish Stocks ◽  
Stock Biomass ◽  
Clear Link ◽  
Spawning Stock ◽  
The Mean

The oldest and largest individuals are disappearing from many fish stocks worldwide as a result of overexploitation. This has been suggested to impair recruitment through decreasing the reproductive capacity of the spawners and increasing the mortality rate of the offspring. By using a time series on spawners biomass by age class for Arcto-Norwegian cod (Gadus morhua) from 1913–2004, I have documented pronounced changes in the spawning stock, including a trend towards younger fish, a less diverse distribution across ages, and a declining proportion of repeat spawners. Despite the total spawning stock biomass (SSB) being at similar levels now as in 1933, the mean age in the SSB has declined from 10–12.5 years to 7–8 years during the study period, and the percentage of fish of age 10 or above in the SSB has decreased from ~97% to ~10%. Contrary to earlier theoretical and experimental studies, no clear link between age structure and recruitment was found here. Recruitment to the Arcto-Norwegian cod stock may thus be more robust towards spawner juvenation than expected, possibly because of strong recruitment compensation.

scholarly journals Population Viability and Resource Competition on North Brother Island: Conservation Implications for Tuatara (Sphenodon Punctatus) and Duvaucel's Gecko (Hoplodactylus Duvaucelii)

2021 ◽  
Author(s):  
◽  
Joanna Wilson
Keyword(s):  
Sex Ratio ◽  
Population Size ◽  
Body Condition ◽  
Resource Competition ◽  
Adult Population ◽  
Population Viability ◽  
Adult Survival ◽  
Intraspecific Interactions ◽  
Sphenodon Punctatus

<p>Population viability for small, isolated populations is determined by many factors, particularly demographic stochasticity. Coexistence of communities is promoted through resource partitioning, particularly if species share similar niche requirements. Demographic characteristics, long-term trends and patterns of partitioning were investigated for two reptile species: tuatara (Sphenodon punctatus) and Duvaucel's gecko (Hoplodactylus duvaucelii), using mark recapture techniques on North Brother Island, New Zealand. Capture time and location were recorded as well as snout-vent length, mass and sex of individuals. Adult population size, sex ratio, survival and recapture probability for both species were estimated. Intervention will be needed to prevent population collapse for tuatara, as the population is male-biased (3.24 males: 1 female), with sub-adults exhibiting a stronger bias (4.1 males: 1 female). The total population size is estimated at 390-437 adults, with high adult survival (95%). The Duvaucel's gecko population is stable enough to be harvested for translocation, as the population was estimated at 583-677 adults, with an even sex ratio. Adult survival was high (92%) and longevity is at least 43-50 years. Patterns in partitioning suggest tuatara are excluding Duvaucel's gecko as tuatara occupy vegetated areas and few animals were caught at the same time in the same place as a member of the other species (~10%). Long-term site fidelity appears to occur in both species as the majority of animals were captured previously within 10m (tuatara) or 15m (Duvaucel's gecko) of their 2008 location, and travelled less than 2m per year on average. Tuatara show an overall decline in body condition since 1957, which is more rapid in females, and may be related to intraspecific interactions and density-dependent effects. Gecko body condition is not declining, suggesting no negative effects at the population level are occurring as a result of competitive exclusion. This study indicates that characteristics that have implications for population viability have the capacity to differ, even for species with similar niche requirements occupying the same habitat, and supports the considerable value of long-term monitoring.</p>

scholarly journals Experience of surgical treatment of infective endocarditis in children

2019 ◽  
pp. 67-83
Author(s):  
L. Prokopovуch ◽  
O. Golovenko ◽  
Y. Truba ◽  
M. Rudenko ◽  
O. Senyko ◽  
...  
Keyword(s):  
Surgical Treatment ◽  
Heart Defects ◽  
Subcutaneous Fat ◽  
Clinical Manifestations ◽  
Infectious Endocarditis ◽  
Average Weight ◽  
Kaplan Meier ◽  
The Mean

Surgical treatment of infectious endocarditis in children, single-center experience. The paper analyzes the experience of surgical treatment of infectious endocarditis (IE) in children. In the period from January 1999 to July 2019, 69 children with IE were operated at National Amosov Institute of Cardiovascular Surgery of NAMS of Ukraine, 44 of them (63.8%) developed the disease on the background of congenital heart defects (CHD). The mean age of the patients at the time of surgery was 9.1 ± 6.1 years. The average weight is 31.5 ± 21.7 (3.6 to 85 kg). The duration of the disease at the time of hospitalization was 5.3 ± 1.1 months. The average duration of the fever before hospitalization was 10.2 ± 8.5 weeks. Among the causes of IE, we observed three groups of inflammatory diseases: infections of the skin and subcutaneous fat in 15 (21.7%) cases, pathology of ENT – organs – 14 (20.2%) and broncho-pulmonary diseases – 9 (13.1%) cases. The risk factors were: presence of CHD – 44 (63.7%) and also nosocomial factors. The microbiological spectrum of pathogens included gram-positive microorganisms – 33 (71.7%), gram-negative microorganisms 4 (8.7%) and fungal microflora 9 (19.6%). The mean values of bypass circulation were 111.5 ± 62.4 minutes, and the time of aortic clamping was 71.4 ± 43.9 minutes, respectively. Hospital mortality in the general group of patients was 4 (5.8%) cases. In the follow-up period, 59 patients were examined, representing 90.7% of those discharged at the hospital stage. The observation period lasted from one month to 19.4 years (9.6 ± 5.7 years). According to the Kaplan-Meier analysis, the cumulative survival rate of patients in the CHD group at one year after surgery was 97.1%, at 10 years – 93.5%; after 15 years – 93.5%. Survival in the non-CHD group at 5, 10, and 15 years was 100%. In the long term, two patients died (3.4%). The recurrence rate of IE in the distant period was 2 (3.4%) cases. The incidence of long-term reoperation was 8 (13.6%) cases, three were recurrent IE and five were non-recurrent. According to Kaplan-Meier analysis, the proportion of patients without recurrent surgery in the long-term follow-up at 5 years was 87.9%, at 10 years – 84.1%, after 15 years – 77.1% in the CHD group. In the group without CHD 5 years – 95.2%, 10 years – 95.2%, 15 years – 81.6%. In the long term, as a result of performed surgical interventions, the regression of clinical manifestations of heart failure was noted in the majority of patients.

Testing Predictions of Marine Fish and Shellfish Landings from Environmental Variables

1987 ◽  
Vol 44 (9) ◽  
pp. 1568-1573 ◽  
Author(s):  
K. F. Drinkwater ◽  
R. A. Myers
Keyword(s):  
Environmental Variables ◽  
Environmental Effect ◽  
Degrees Of Freedom ◽  
Gulf Of Maine ◽  
Fishing Effort ◽  
Fish Stocks ◽  
Environmental Models ◽  
The Mean ◽  
Fish And Shellfish

Previous studies by Sutcliffe and co-workers using exploratory analysis found correlations between environmental variables and lagged annual catch for several Gulf of St. Lawrence and Gulf of Maine fish and shellfish stocks. The present study tests these relationships using recent data. For 6 of the 13 stocks investigated, correlations between the 9–14 yr of new catch data and that predicted from the environmental models remained high (r > 0.5) and of the same sign; however, individually none was statistically significant (p > 0.05) after accounting for the loss of degrees of freedom due to the high autocorrelation in the data. The hypothesis of an overall environmental effect on the landings was considered. It could not be substantiated as the correlation coefficient for 5 of the 13 stocks reversed sign using the new data, but changes in fishing effort are believed to mask detection of environmentally induced variability in the landings of many stocks. The utility of environmentally based predictions was also tested. Overall, the mean deviations of the predicted catch based on environmental regressions were similar to predictions based on the long-term means but were higher than predictions using lagged catch. Environmentally based predictions of landings for invertebrate stocks were generally more accurate than those for fish stocks.

scholarly journals Population Viability and Resource Competition on North Brother Island: Conservation Implications for Tuatara (Sphenodon Punctatus) and Duvaucel's Gecko (Hoplodactylus Duvaucelii)

2021 ◽  
Author(s):  
◽  
Joanna Wilson
Keyword(s):  
Sex Ratio ◽  
Population Size ◽  
Body Condition ◽  
Resource Competition ◽  
Adult Population ◽  
Population Viability ◽  
Adult Survival ◽  
Intraspecific Interactions ◽  
Sphenodon Punctatus

<p>Population viability for small, isolated populations is determined by many factors, particularly demographic stochasticity. Coexistence of communities is promoted through resource partitioning, particularly if species share similar niche requirements. Demographic characteristics, long-term trends and patterns of partitioning were investigated for two reptile species: tuatara (Sphenodon punctatus) and Duvaucel's gecko (Hoplodactylus duvaucelii), using mark recapture techniques on North Brother Island, New Zealand. Capture time and location were recorded as well as snout-vent length, mass and sex of individuals. Adult population size, sex ratio, survival and recapture probability for both species were estimated. Intervention will be needed to prevent population collapse for tuatara, as the population is male-biased (3.24 males: 1 female), with sub-adults exhibiting a stronger bias (4.1 males: 1 female). The total population size is estimated at 390-437 adults, with high adult survival (95%). The Duvaucel's gecko population is stable enough to be harvested for translocation, as the population was estimated at 583-677 adults, with an even sex ratio. Adult survival was high (92%) and longevity is at least 43-50 years. Patterns in partitioning suggest tuatara are excluding Duvaucel's gecko as tuatara occupy vegetated areas and few animals were caught at the same time in the same place as a member of the other species (~10%). Long-term site fidelity appears to occur in both species as the majority of animals were captured previously within 10m (tuatara) or 15m (Duvaucel's gecko) of their 2008 location, and travelled less than 2m per year on average. Tuatara show an overall decline in body condition since 1957, which is more rapid in females, and may be related to intraspecific interactions and density-dependent effects. Gecko body condition is not declining, suggesting no negative effects at the population level are occurring as a result of competitive exclusion. This study indicates that characteristics that have implications for population viability have the capacity to differ, even for species with similar niche requirements occupying the same habitat, and supports the considerable value of long-term monitoring.</p>

Uncertainty in assessing the viability of the Powerful Owl Ninox strenua in Victoria, Australia

1999 ◽  
Vol 5 (2) ◽  
pp. 144 ◽  
Author(s):  
Michael A. McCarthy ◽  
Alan Webster ◽  
Richard H. Loyn ◽  
Kim W. Lowe
Keyword(s):  
Management Strategies ◽  
Population Viability Analysis ◽  
Population Viability ◽  
Large Field ◽  
Adult Survival ◽  
Metapopulation Dynamics ◽  
Viability Analysis ◽  
Term Monitoring ◽  
Predicted Risk

A model of the metapopulation dynamics of Powerful Owls Ninox strenua in Victoria, Australia is described, and its parameters were derived from available data. Sensitivity analysis indicates that the survival rate of adult owls is the most important parameter in the model. Because estimates of this parameter are uncertain, the predictions of the model are uncertain and unreliable. Using the best estimates of the parameters, the predicted risk of decline across Victoria is low, and local populations larger than 100 pairs have a low risk of extinction. If the lower estimates of adult and sub-adult survival are used, the abundance of Powerful Owls across Victoria is predicted to decline exponentially and faces extinction from deterministic forces. A prohibitively large field programme involving monitoring of individuallyrecognizable owls would be required to obtain an improved estimate of adult survival, and so further use of population viability analysis to assess the adequacy of particular management strategies is unlikely to be useful for this species. An alternative is to establish a long-term monitoring programme to document changes in abundance of the species in logged and unlogged landscapes.

Body size and age structure of the endangered Clark’s lizard (Darevskia clarkorum) populations from two different altitudes in Turkey

2016 ◽  
Vol 37 (4) ◽  
pp. 450-456 ◽  
Author(s):  
Ufuk Bülbül ◽  
Muammer Kurnaz ◽  
Ali İhsan Eroğlu ◽  
Halime Koç ◽  
Bilal Kutrup
Keyword(s):  
Body Size ◽  
Age Structure ◽  
Sexual Maturity ◽  
Age At Maturity ◽  
Maximum Life Span ◽  
Breeding Populations ◽  
Size And Age Structure ◽  
Males And Females ◽  
The Mean ◽  
Different Altitudes

We investigated age structure, body size and longevity in two breeding populations ofDarevskia clarkoruminhabiting altitudes ranging from 450 m a.s.l. (Kamilet) to 2250 m a.s.l. (Başyayla) in Turkey by skeletochronology performed on the phalanges. The mean age was found to be 6 years in the Kamilet population and 7 years in the Başyayla population. The maximum life span was 10 years in the lowland population while it was 12 years in the highland population. Age at sexual maturity of both males and females was 1-2 years in the lowland population while it was 2-3 for both sexes in the highland population. Both age and SVL of specimens from the Kamilet population were significantly different between the sexes while age and SVL did not differ significantly between the sexes in Başyayla population. As a conclusion, we observed that the mean age, longevity and age at maturity were increased by altitude while there was a decrease based on the mean SVL in the highland population ofD. clarkorum. Our data on body size, longevity and age at sexual maturity may contribute to conservation efforts for this endangered species.

Acute and Chronic Changes in Platelet Volume and Count After Cardiopulmonary Bypass Induced Thrombocytopenia in Man

1987 ◽  
Vol 57 (01) ◽  
pp. 55-58 ◽  
Author(s):  
J F Martin ◽  
T D Daniel ◽  
E A Trowbridge
Keyword(s):  
Platelet Count ◽  
Mean Platelet Volume ◽  
Artery Bypass ◽  
Bypass Graft ◽  
Control Group ◽  
Artery Bypass Graft ◽  
Platelet Volume ◽  
Young Males ◽  
The Mean

SummaryPatients undergoing surgery for coronary artery bypass graft or heart valve replacement had their platelet count and mean volume measured pre-operatively, immediately post-operatively and serially for up to 48 days after the surgical procedure. The mean pre-operative platelet count of 1.95 ± 0.11 × 1011/1 (n = 26) fell significantly to 1.35 ± 0.09 × 1011/1 immediately post-operatively (p <0.001) (n = 22), without a significant alteration in the mean platelet volume. The average platelet count rose to a maximum of 5.07 ± 0.66 × 1011/1 between days 14 and 17 after surgery while the average mean platelet volume fell from preparative and post-operative values of 7.25 ± 0.14 and 7.20 ± 0.14 fl respectively to a minimum of 6.16 ± 0.16 fl by day 20. Seven patients were followed for 32 days or longer after the operation. By this time they had achieved steady state thrombopoiesis and their average platelet count was 2.44 ± 0.33 × 1011/1, significantly higher than the pre-operative value (p <0.05), while their average mean platelet volume was 6.63 ± 0.21 fl, significantly lower than before surgery (p <0.001). The pre-operative values for the platelet volume and counts of these patients were significantly different from a control group of 32 young males, while the chronic post-operative values were not. These long term changes in platelet volume and count may reflect changes in the thrombopoietic control system secondary to the corrective surgery.

Multi-Center Calibration of the Second Reference Material for Thromboplastin, Rabbit, Plain, Coded CRM 149R

1991 ◽  
Vol 65 (03) ◽  
pp. 263-267 ◽  
Author(s):  
A M H P van den Besselaar ◽  
R M Bertina
Keyword(s):  
Reference Material ◽  
Standard Error ◽  
Standard Errors ◽  
Sensitivity Index ◽  
Long Term Stability ◽  
Significant Bias ◽  
The Mean ◽  
The Relationship ◽  
International Sensitivity Index

SummaryIn a collaborative trial of eleven laboratories which was performed mainly within the framework of the European Community Bureau of Reference (BCR), a second reference material for thromboplastin, rabbit, plain, was calibrated against its predecessor RBT/79. This second reference material (coded CRM 149R) has a mean International Sensitivity Index (ISI) of 1.343 with a standard error of the mean of 0.035. The standard error of the ISI was determined by combination of the standard errors of the ISI of RBT/79 and the slope of the calibration line in this trial.The BCR reference material for thromboplastin, human, plain (coded BCT/099) was also included in this trial for assessment of the long-term stability of the relationship with RBT/79. The results indicated that this relationship has not changed over a period of 8 years. The interlaboratory variation of the slope of the relationship between CRM 149R and RBT/79 was significantly lower than the variation of the slope of the relationship between BCT/099 and RBT/79. In addition to the manual technique, a semi-automatic coagulometer according to Schnitger & Gross was used to determine prothrombin times with CRM 149R. The mean ISI of CRM 149R was not affected by replacement of the manual technique by this particular coagulometer.Two lyophilized plasmas were included in this trial. The mean slope of relationship between RBT/79 and CRM 149R based on the two lyophilized plasmas was the same as the corresponding slope based on fresh plasmas. Tlowever, the mean slope of relationship between RBT/79 and BCT/099 based on the two lyophilized plasmas was 4.9% higher than the mean slope based on fresh plasmas. Thus, the use of these lyophilized plasmas induced a small but significant bias in the slope of relationship between these thromboplastins of different species.

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