Some Methods for Estimating Ocean Mortality of Pacific Salmon and Applications

1965 ◽  
Vol 22 (1) ◽  
pp. 33-51 ◽  
Author(s):  
R. A. Fredin
Keyword(s):  
Mortality Rate ◽  
Freshwater Fish ◽  
Pacific Salmon ◽  
Mortality Rates ◽  
Natural Mortality ◽  
Bristol Bay ◽  
The Third

Three methods for estimating oceanic natural mortality rates of Pacific salmon under certain survival conditions are presented. Estimates of ocean mortality rates of Bristol Bay and Karluk sockeye are given. The mortality rate during the year immediately preceding the last 2 months of ocean life of Bristol Bay sockeye that migrated to sea as 3-freshwater fish in 1956 and returned as mature 3-ocean fish in 1959 is estimated to be 28.9%. The average ocean mortality rate during the penultimate year of life of 3-ocean Bristol Bay sockeye is estimated to be 19.5% for the years 1956–57 to 1960–61. The natural mortality rate during the third year of ocean life of 3-freshwater Karluk sockeye is estimated to be 28.2%. Corresponding estimates of average monthly instantaneous mortality rates are 0.028, 0.018, and 0.031, respectively.

scholarly journals Characteristics of mortality in the Orenburg region population in 2011-2017

2020 ◽  
Vol 5 (2) ◽  
pp. 99-104
Author(s):  
Evgenii L. Borschuk ◽  
Dmitrii N. Begun ◽  
Tatyana V. Begun
Keyword(s):  
Mortality Rate ◽  
Causes Of Death ◽  
Age Groups ◽  
Circulatory System ◽  
Mortality Rates ◽  
Female Population ◽  
Orenburg Region ◽  
The Third ◽  
Circulatory System Diseases ◽  
External Causes

Objectives - to study the mortality indicators, their dynamics and structure, in the population of the Orenburg region in the period of 2011-2017. Material and methods. The study was conducted using the data from the territorial authority of statistics in the Orenburg region in the period from 2011 to 2017. The analytical, demographic and statistical methods were implemented for the study of the demographic indicators. Results. Cities and municipal settlements of the Orenburg region with high mortality indicators were included in the second and fourth clusters during the cluster analysis. The first and third clusters included cities and municipal settlements with an average mortality. The most favorable position has the Orenburg area with the lowest mortality rate in the region in 2017 - 8.4%. The dynamics of mortality rates among the male and female population tends to decrease, more pronounced dynamics is in men. Though, the male population is characterized by higher mortality rates in all age groups. The leading position among the causes of death is taken by diseases of the circulatory system (46.3% of the total mortality). The second position is occupied by tumors (17.2%), the third - by external causes (8.4%). Mortality from circulatory system diseases and from external causes has reduced. The dynamics of mortality from tumors does not change significantly. The rank of leading causes of death is not identical in the clusters: in the third and fourth clusters, the other causes occupy the second place in the structure of mortality, while tumors occupy the third. Conclusion. In the Orenburg region, the mortality rate is higher than overage in the Russian Federation by 0.9 per 1000 people. The study revealed significant territorial differences in the mortality rates. In general, the mortality among men in all age groups is higher than the mortality of women. The mortality rate from diseases of the circulatory system plays the leading role in the structure of mortality, but has the tendency for decline. Until 2006, the mortality from external causes ranked the second place, now the second place is taken by death from tumors The mortality from external causes is decreasing; mortality from tumors does not change significantly. The obtained results could be used by local authorities in developing the program of public health protection and assessing its effectiveness.

An Application of Computers to the Estimation of Exploited Populations

1969 ◽  
Vol 26 (1) ◽  
pp. 179-189
Author(s):  
K. Radway Allen
Keyword(s):  
Mortality Rate ◽  
Age Distribution ◽  
The Other ◽  
Population Estimates ◽  
Distribution Data ◽  
Natural Mortality ◽  
Computer Programme ◽  
Total Catch ◽  
The Third

This paper describes a computer programme for the estimation of the size of exploited populations by methods described in Allen (1966, J. Fish. Res. Bd. Canada 23: 1553–1574). Although these methods were originally developed for use on whale populations, they are applicable to any other populations where suitable data are available. The essential data are the total catch, the catch for a known amount of effort, and the age distribution of the catch, all for a series of years. An estimate of natural mortality rate is also required but population estimates may be obtained for up to 10 values of this parameter in a single computer run.The entire programme incorporates six subroutines, as well as the main controlling programme. One subroutine reads in the catch and effort data, a second reads in the age distribution data for each year and, if necessary, converts it according to a predetermined transformation from age expressed in terms of whale ear-plug laminations to age in years. The third subroutine estimates the rate of recruitment as the proportion of newly recruited animals in the catch for each year, using the method of Allen (1966). The other three subroutines derive population estimates, using the "q," modified DeLury, and actual and expected catch methods (Allen, 1966). As many sets of data as desired may be processed in a single computer run.

Estimations of Ocean Mortality Rates for Pacific Salmon (Oncorhynchus)

1962 ◽  
Vol 19 (4) ◽  
pp. 561-589 ◽  
Author(s):  
Robert R. Parker
Keyword(s):  
Mortality Rate ◽  
Sockeye Salmon ◽  
Pacific Salmon ◽  
Pink Salmon ◽  
Total Mortality ◽  
Mortality Rates ◽  
Mortality Factor ◽  
Sampling Errors ◽  
Instantaneous Rate ◽  
Factor C

A conceptual model representing natural marine mortality rates of Pacific salmon is developed. Ocean mortality rate (q) is taken as the base to which coastal mortality rates of juveniles (c) and of adults (k) are additive factors. The effect of marking is taken as a multiplicative factor (m) of the instantaneous rate (i) where i = q + c + k. Together with time these values are incorporated into the balanced equation[Formula: see text]where N0 denotes the population entering the sea and R1, R2, R3 denote the returns at succeeding times of maturity. The locus of c + k = f(q) is used to graphically depict all possible combinations of c + k and q within the limits [q, c + k = 0]. Intersections of loci are taken as estimates of values of q and c + k which satisfy two sets of data. Available data for sockeye salmon (O. nerka) from Cultus Lake, Chilko Lake and Hooknose Creek, British Columbia, Karluk River and Bare Lake, Alaska, and Dalnee River, Kamchatka, pink salmon (O. gorbuscha) and chum salmon (O. keta) from Hooknose Creek, chinook salmon (O. tshawytscha) from the coast of Southeast Alaska and coho (O. kisutch) from the Eel River, California, are utilized. It is concluded that ocean mortality is relatively constant, of the order of magnitude q = 0. 32 or S = 73% annually. A juvenile coastal mortality factor (c) apparently exists and is characteristic of the species and race through the media of size of migrants, time spent in the costal area, and geography. An adult coastal factor (k) may exist but is of negligible influence on the total mortality rate. While the data utilized collectively may be considered as extensive, serious defects in sampling errors and undefined variability were encountered. It is doubted that mortality rates can be more accurately defined from any repetition of experiments used, hence a more direct approach is indicated for solution of this problem.

scholarly journals Growth, maturation, and longevity of maturation cohorts of Norwegian spring-spawning herring

2004 ◽  
Vol 61 (2) ◽  
pp. 165-175 ◽  
Author(s):  
Raymond J.H. Beverton ◽  
Arvid Hylen ◽  
Ole-Johan Østvedt ◽  
John Alvsvaag ◽  
Terence C. Iles
Keyword(s):  
Mortality Rate ◽  
Small Proportion ◽  
Stock Assessment ◽  
Adult Life ◽  
Total Mortality ◽  
Mortality Rates ◽  
Natural Mortality ◽  
Marine Research ◽  
First Time ◽  
Age At Maturation

Abstract In 1907, the Bergen Institute of Marine Research started regular sampling of scales and lengths from landings of mature Norwegian spring-spawning herring. The actual age of each fish when caught was recorded, and from the early 1920s also the age at which it spawned for the first time. The present analyses concern biological samples secured during the fishing seasons 1940–1964. Herring in this stock do not all reach maturity at the same age. A small proportion of any one year class matures at 3 years. The majority matures from the age of 4–7 years, and a small proportion of some year classes at 8 and even 9 years of age. Subsequent age composition and growth of each maturation cohort were followed throughout mature life after spawning for the first time. The maximum age was found to increase with age at maturation, rising to an asymptote of about 22 years. The von Bertalanffy parameter L∞ shows an increasing trend with age at maturation, while K decreases. There is no strict length threshold at maturation and the curve joining the length at which each maturation cohort reaches maturity is less steep than the growth curve itself over the range of maturation ages. The data suggest that fish in this stock spawn, on average, eight times during a period of their life history in which the mortality rate is independent of age. After these eight spawnings, at an age referred to in this paper as the hinge age, the mortality rate increases sharply. Thus, the adult life is divided into two phases, called here pre-senescent and senescent. The total mortality rates in the pre-senescent phase are relatively stable for all maturation cohorts 3–9, but there is some evidence of a trend towards higher mortality rates during the senescent phase for the youngest maturing fish. This trend is caused mainly by a reduced natural mortality in the fish that mature when older. These findings have interesting demographic implications. Additional mortality due to fishing will change the relative contribution of young and old maturation cohorts in the senescent phase, thus making it appear that natural mortality is dependent on the intensity of fishing. Consequently, for stock assessment, analysis on a cohort basis seems advisable.

Estimation of Sea Mortality Rates for the 1960 Brood-Year Pink Salmon of Hook Nose Creek, British Columbia

1964 ◽  
Vol 21 (5) ◽  
pp. 1019-1034 ◽  
Author(s):  
Robert R. Parker
Keyword(s):  
British Columbia ◽  
Mortality Rate ◽  
Marine Environment ◽  
Pink Salmon ◽  
Mortality Rates ◽  
Natural Mortality ◽  
Two Stage ◽  
Fishing Season ◽  
Salmon Fry ◽  
Bella Coola

Seaward migrating pink salmon fry at Hook Nose Creek, British Columbia, were estimated to total 1,153,000 in 1961. Of these, 41.5% or 479,000, were marked by amputation of both ventral fins (BV). Following this marking 36,900 fingerling were captured in the marine environment and marked by removal of the adipose and right ventral fins (ARV). During the 1962 fishing season 1,160,645 adult pinks were examined and 7050 BV and 184 ARV marks recognized. For the Hook Nose Creek stock, survival at sea from natural causes is shown to approximate 22% and the rate of exploitation was 95%. This stock is shown to be more exposed to fishing than the Bella Coola stock, for which a rate of exploitation of 69–80% is estimated. Rate of exploitation for Dean Channel stocks is even lower. These differences are explained as due to times of entry and rates of travel through the fishery. The two-stage marking experiment failed to estimate the natural mortality rate of juvenile pinks during the initial 5 weeks of sea life because of this dissimilarity between rates of exploitation on the stocks in the area.

An Estimate of Ocean Mortality of Bristol Bay Sockeye Salmon Three Years at Sea

1968 ◽  
Vol 25 (6) ◽  
pp. 1219-1227 ◽  
Author(s):  
Stephen B. Mathews
Keyword(s):  
Mortality Rate ◽  
Freshwater Fish ◽  
Sockeye Salmon ◽  
Population Estimation ◽  
Bristol Bay ◽  
Age Composition ◽  
Dichotomous Population ◽  
Sea Fish ◽  
Annual Mortality ◽  
High Seas

The method of population estimation based on change in composition of a dichotomous population was applied to Bristol Bay sockeye salmon to estimate the mortality rate of 3-ocean (3 years at sea) fish during their final year in the ocean. A difference in freshwater age composition between 1-ocean immatures in 1964 and 2-ocean immatures in 1965 was evident in samples taken in the high seas. This difference was apparently due to a greater tendency of 2-freshwater fish than 1-freshwater fish to mature after 2 years at sea. The known quantities of these two freshwater categories in the mature 2-ocean run of 1965 enabled an estimate of the population of 2-ocean immatures at sea in 1965. From this estimate and the quantity of 3-ocean matures in the 1966 run, the annual mortality rate was estimated to be.42.

scholarly journals High Spring Mortality of Adult Richardson’s Ground Squirrels, Urocitellus richardsonii, Associated with a Severe Rainstorm in Southwestern Saskatchewan

2012 ◽  
Vol 126 (2) ◽  
pp. 148
Author(s):  
Gilbert Proulx
Keyword(s):  
Mortality Rate ◽  
Ground Squirrel ◽  
Mortality Rates ◽  
Ground Squirrels ◽  
Natural Mortality ◽  
The Mean ◽  
Strong Winds ◽  
Heavy Rains ◽  
Urocitellus Richardsonii

Heavy rains with strong winds in southwestern Saskatchewan from 20 to 29 May 2010 flooded fields where adult Richardson’s Ground Squirrels (Urocitellus richardsonii) had recently been live–trapped. Natural mortality rates in six marked populations (n = 11 to 29 animals) ranged from 9.1 to 42.9%. The mean mortality rate of populations (28.9%) was significantly greater than that estimated for four populations (8.5%) studied in April and May 2007 and 2008 during drought periods. This finding is in agreement with past studies on other ground squirrel species which showed that spring snowstorms and heavy rains caused an increase in natural mortality rates.

Marine Mortality Schedules of Pink Salmon of the Bella Coola River, Central British Columbia

1968 ◽  
Vol 25 (4) ◽  
pp. 757-794 ◽  
Author(s):  
Robert R. Parker
Keyword(s):  
Mortality Rate ◽  
Early Life ◽  
Pink Salmon ◽  
Mortality Rates ◽  
Early Mortality ◽  
Initial Population ◽  
Natural Mortality ◽  
Time Period ◽  
Marking Technique ◽  
Bella Coola

The hypothesis that natural mortality rates of pink salmon during early life are generally much larger than during the later period has been tested for 3 brood-years of the Bella Coola River stock using a two-stage marking technique. Average daily losses to the population during the first 40 days are estimated to vary between 2 and 4%, and for the later 410-day period between 0.4 and 0.8%. These rates produce losses amounting to between 59 and 77% of the initial population during the first 40 days. Of the population surviving at 40 days, further losses of between 78 and 95% occurred. The latter losses are considered to be maximum estimates because of bias introduced by catches of unknown magnitude. Thus, although the early mortality is exceeded by the later, the time period is approximately 10 times as long, and the intensity of the mortality rate is much higher during early sea life.

scholarly journals COVID-19 Case Mortality Rates Continue to Decline in Florida

2020 ◽  
Author(s):  
Jeffrey E Harris
Keyword(s):  
Mortality Rate ◽  
Medical Care ◽  
Mortality Rates ◽  
Hospitalized Patients ◽  
Significant Decline ◽  
Hospital Treatment ◽  
Age Group ◽  
The Third ◽  
Case Mortality

We studied COVID-19 case mortality in Florida among four successive cohorts of persons at least 50 years of age, each of whom we followed for 28 to 48 days from date of diagnosis. The cohorts were separated by date of diagnosis into four nonoverlapping intervals: March 29 - April 18; April 29 - May 19; May 21 - June 10; and June 14 - July 4, 2020. Case mortality rates declined consistently and significantly over the course of the four intervals: 57% among those aged 50-59 years; 62% among those aged 60-69 years; 52% among those aged 70-79 years; and 34% among those aged 80 or more years. These findings were consistent with progressive improvements in the medical care of COVID-19 patients. We further studied case mortality by hospitalization status. The case mortality rate among hospitalized patients aged 60-69 years fell significantly from the first to the third interval. During the fourth interval, an apparent rise in mortality among hospitalized patients in the same age group was mirrored by a significant decline in mortality among those not hospitalized. These findings were consistent with the out-of-hospital treatment of some patients who would have previously been hospitalized.

scholarly journals Coarse woody habitat does not predict largemouth bass young of year mortality during the open-water season

2019 ◽  
Vol 76 (6) ◽  
pp. 998-1005 ◽  
Author(s):  
Jacob P. Ziegler ◽  
Colin J. Dassow ◽  
Stuart E. Jones ◽  
Alexander J. Ross ◽  
Christopher T. Solomon
Keyword(s):  
Mortality Rate ◽  
Freshwater Fish ◽  
Largemouth Bass ◽  
Micropterus Salmoides ◽  
Open Water ◽  
Mortality Rates ◽  
In Situ Tests ◽  
Coarse Woody Habitat ◽  
The Relationship

Littoral structure is often assumed to provide refuge to young of year (YOY) freshwater fish species, but empirical in situ tests of this relationship are lacking. We estimated mortality rates of YOY largemouth bass (Micropterus salmoides) over the open-water season in 13 lakes in northern Wisconsin and Michigan using repeated snorkel surveys. Our goal was to test the hypothesis that mortality rate is negatively related to the abundance of littoral coarse woody habitat, which ranged from 3 to 1500 pieces of wood per kilometre of shoreline in these lakes. Instantaneous mortality rates were well-constrained and ranged from 0.04 to 0.19 among the 13 lakes. Mortality was not related to coarse woody habitat abundance. Our results suggest that the relationship between coarse woody habitat and YOY mortality might not be as strong or universal as is often assumed.

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