Hypothesis Concerning “Natural” Mortality in Psychiatry

1989 ◽  
pp. 52-66
Author(s):  
Ph. Corten ◽  
M. Ribourdouille
Keyword(s):  
Natural Mortality

Variation in size distribution of juvenile pink shrimps Farfantepenaeus brasiliensis and F. paulensis in the estuarine-adjacent ocean area of Cananéia, south-eastern coast of Brazil

2021 ◽  
Vol 101 (1) ◽  
pp. 117-129
Author(s):  
Dalilla da Silva Salvati ◽  
Júlia Fernandes Perroca ◽  
Sabrina Morilhas Simões ◽  
Antonio Leão Castilho ◽  
Rogerio Caetano da Costa
Keyword(s):  
Development Time ◽  
Carapace Length ◽  
Growth Parameters ◽  
Adult Population ◽  
Eastern Coast ◽  
Natural Mortality ◽  
Juvenile Phase ◽  
Juvenile Recruitment ◽  
Estuarine Lagoon ◽  
Closed Season

AbstractThe study characterized the structure of juveniles and sub-adults of Farfantepenaeus brasiliensis and F. paulensis in the Cananéia-Iguape estuarine lagoon system and its adjacent coastal area by evaluating the period of juvenile recruitment, sex ratio, growth, longevity, natural mortality, and development time until the late juvenile phase. Samples were collected from July 2012 to June 2014. Shrimps were identified by species and sex, and measured (carapace length – CL mm); 889 individuals of F. brasiliensis and 848 of F. paulensis were analysed. Females were more abundant than males for both species. The growth parameters of F. brasiliensis were: CL∞ = 45.5 mm, k = 1.8 year−1 for males and CL∞ = 55.2 mm, k = 1.6 year−1 for females; longevity of 2.52 years (males) and 2.88 years (females); and natural mortality of 1.71 (males) and 1.55 (females). For F. paulensis, the following values were observed: CL∞ = 40.7 mm, k = 2.3 year−1 for males and CL∞ = 56.5 mm, k = 1.9 year−1 for females; longevity of 2.04 years (males) and 2.37 years (females); and natural mortality of 2.39 (males) and 2.05 (females). The juvenile recruitment of both species peaked in January 2014. The development time until late juvenile phase was ~7 months (F. brasiliensis) and ~5 months (F. paulensis). Even though the highest abundance of juveniles did not occur in the closed season, fishing is forbidden in the estuarine area and the migration towards the adult population occurred close to or even during the closed season.

Climate Change May Cause Shifts in Growth and Instantaneous Natural Mortality of American Shad Throughout Their Native Range

2021 ◽  
Author(s):  
Erin K. Gilligan‐Lunda ◽  
Daniel S. Stich ◽  
Katherine E. Mills ◽  
Michael M. Bailey ◽  
Joseph D. Zydlewski
Keyword(s):  
Climate Change ◽  
American Shad ◽  
Natural Mortality ◽  
Native Range

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.

scholarly journals Caveats with estimating natural mortality rates in stock assessment models using age aggregated catch data and abundance indices

2021 ◽  
Vol 243 ◽  
pp. 106071
Author(s):  
M. Aldrin ◽  
F.L. Aanes ◽  
I.F. Tvete ◽  
S. Aanes ◽  
S. Subbey
Keyword(s):  
Stock Assessment ◽  
Mortality Rates ◽  
Natural Mortality ◽  
Catch Data ◽  
Abundance Indices

Natural mortality from poor condition in Atlantic cod (Gadus morhua)

2000 ◽  
Vol 57 (4) ◽  
pp. 826-836 ◽  
Author(s):  
Jean-Denis Dutil ◽  
Yvan Lambert
Keyword(s):  
Gadus Morhua ◽  
Atlantic Cod ◽  
Negative Impact ◽  
Fish Muscle ◽  
Early Summer ◽  
Wild Fish ◽  
Natural Mortality ◽  
Muscle Lactate ◽  
Lactate Dehydrogenase Activity ◽  
Poor Condition

The extent of energy depletion was assessed in Atlantic cod (Gadus morhua) in spring and early summer (1993-1995) to assess relationships between poor condition and natural mortality. Several indices of condition were compared in wild fish in the northern Gulf of St. Lawrence and in fish exposed to a prolonged period of starvation in laboratory experiments. Discriminant analyses classified only a small fraction of the wild fish as similar to cod that did not survive and a much larger fraction as similar to cod that survived starvation. This percentage increased from April to May and peaked in June 1993 and 1994. Condition factor and muscle somatic index allowed a clear distinction between live and dead fish. Muscle lactate dehydrogenase activity suggested that cod had experienced a period of negative growth early in 1993, 1994, and 1995. Fish classified as similar to starved individuals were characterized by a higher gonad to liver mass ratio than others. Reproduction may have a negative impact on survival not only in spring but also later into summer, as some individuals were found not to have recovered by late summer. This study shows that natural mortality from poor condition contributed to lower production in the early 1990s.

Production, Mortality, And Sustainable Yield Of Northwest Atlantic Harp Seals (Pagophilus groenlandicus)

1978 ◽  
Vol 35 (9) ◽  
pp. 1249-1261 ◽  
Author(s):  
G. H. Winters
Keyword(s):  
Population Size ◽  
Total Population ◽  
Historical Data ◽  
Maximum Sustainable Yield ◽  
Sustainable Yield ◽  
Natural Mortality ◽  
Northwest Atlantic ◽  
The Past ◽  
Relative Contribution ◽  
Pagophilus Groenlandicus

From recent and historical data the natural mortality rate of adult harp seals (Pagophilus groenlandicus) is estimated to be 0.10 which is within the range of previous estimates (0.08–0.11). New estimates of bedlamer and 0-group natural mortality rates were not significantly different from those of adult seals. Pup production estimates from survival indices agreed well with those from sequential population analyses and indicated a decline from about 350 000 animals in the early 1950s to about 310 000 animals in the early 1970s. Over the same period the 1+ population size declined from 2.5 to 1.1 million animals but has been increasing at the rate of 3%/yr since the introduction of quotas in 1972. The relative contribution of the "Front" production to total ("Front" plus Gulf) production during the past decade has fluctuated from 49 to 87%, the average of 64% being very similar to the 61% obtained previously. These fluctuations suggest some interchange between "Front" and Gulf adults and it is concluded that homing in the breeding areas is a facultative rather than obligatory aspect of seal behavior. Thus the heavier exploitation of the "Front" production is probably sufficiently diffused into the total population to avoid serious effects on "Front" production. The maximum sustainable yield of Northwest Atlantic seals harvested according to recent patterns is estimated to be 290 000 animals (80% pups) from a 1+ population size of 1.8 million animals producing 460 000 pups annually. The sustainable yield at present levels of pup production (335 000 animals) is calculated to be 220 000 animals which is substantially above the present TAC of 180 000 animals and coincides with present harvesting strategies designed to enable the seal hunt to increase slowly towards the MSY level. Key words: mortality, production, sustainable yield, population dynamics, marine mammal

scholarly journals Why do many pheasants released in the UK die, and how can we best reduce their natural mortality?

2018 ◽  
Vol 64 (4) ◽  
Author(s):  
Joah R. Madden ◽  
Andrew Hall ◽  
Mark A. Whiteside
Keyword(s):  
Natural Mortality ◽  
The Uk

scholarly journals Tracking red deer population size using deterministic cohort analysis

2021 ◽  
Author(s):  
Valerio Donini ◽  
Luca Corlatti ◽  
Luca Pedrotti
Keyword(s):  
Population Size ◽  
Cervus Elaphus ◽  
Red Deer ◽  
Cohort Analysis ◽  
Cost Effective ◽  
Natural Mortality ◽  
Relative Index ◽  
Deer Population ◽  
Monitoring Tools ◽  
Over Time

AbstractReliable and cost-effective monitoring tools to track population size over time are of key importance for wildlife management and conservation. Deterministic cohort analysis may be used to this aim, especially in hunted populations, but it requires that all mortality events are recorded and that individual age at death is known exactly. In this study, we investigated the reliability of cohort analysis as a relative index to track over-time variation in red deer (Cervus elaphus) abundance, in the absence of exact information about natural mortality and age. Visual tooth inspection was used to age 18,390 individuals found dead or hunted between 1982 and 2020 within the Trentino sector of the Stelvio National Park and the Val di Sole hunting district (Central Italian Alps). Temporal trend of reconstructed population size was checked using spring spotlight counts as a benchmark, through the Buishand range test and a linear model. Our results showed a significant and positive relationship between reconstructed population size and spring spotlight counts between 1982 and 2013, suggesting that cohort analysis could reliably track red deer population trend up to 7 years in the past. With a relative error of  +  1.1 (SD  =  1.5) years in the estimation of age, and fairly stable hunting pressure, our results support the use of deterministic cohort analysis as a relative index of abundance for monitoring red deer over time, even in the absence of exact information about natural mortality. Under violation of assumptions, however, the performance of deterministic reconstruction should be carefully inspected at the management scale.

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