A combined telemetry – tag return approach to estimate fishing and natural mortality rates of an estuarine fish

2009 ◽  
Vol 66 (8) ◽  
pp. 1230-1244 ◽  
Author(s):  
Nathan M. Bacheler ◽  
Jeffrey A. Buckel ◽  
Joseph E. Hightower ◽  
Lee M. Paramore ◽  
Kenneth H. Pollock
Keyword(s):  
Mortality Rate ◽  
Seasonal Pattern ◽  
Mortality Rates ◽  
Sciaenops Ocellatus ◽  
State Agency ◽  
Estuarine Fish ◽  
Joint Analysis ◽  
Natural Mortality ◽  
Combined Model ◽  
Reporting Rates

A joint analysis of tag return and telemetry data should improve estimates of mortality rates for exploited fishes; however, the combined approach has thus far only been tested in terrestrial systems. We tagged subadult red drum ( Sciaenops ocellatus ) with conventional tags and ultrasonic transmitters over 3 years in coastal North Carolina, USA, to test the efficacy of the combined telemetry – tag return approach. There was a strong seasonal pattern to monthly fishing mortality rate (F) estimates from both conventional and telemetry tags; highest F values occurred in fall months and lowest levels occurred during winter. Although monthly F values were similar in pattern and magnitude between conventional tagging and telemetry, information on F in the combined model came primarily from conventional tags. The estimated natural mortality rate (M) in the combined model was low (estimated annual rate ± standard error: 0.04 ± 0.04) and was based primarily upon the telemetry approach. Using high-reward tagging, we estimated different tag reporting rates for state agency and university tagging programs. The combined telemetry – tag return approach can be an effective approach for estimating F and M as long as several key assumptions of the model are met.

Virtual Population Analysis (VPA) Equations for Nonhomogeneous Populations, and a Family of Approximations Including Improvements on Pope's Cohort Analysis

1986 ◽  
Vol 43 (12) ◽  
pp. 2406-2409 ◽  
Author(s):  
Alec D. MacCall
Keyword(s):  
Mortality Rate ◽  
Population Analysis ◽  
Seasonal Pattern ◽  
Cohort Analysis ◽  
Natural Mortality ◽  
Close Approximation ◽  
Virtual Population Analysis ◽  
Virtual Population ◽  
Special Case

A set of "backward" virtual population analysis (VPA) equations relates catch (Ct) from continuous fishing between times t and t + 1 to population n size (Nt, Nt+1) when a portion of the stock is unavailable to fishing. The usual VPA equations become a special case where the entire stock is available (i.e. the stock is homogeneous). A close approximation to the VPA equations is Nt = Nt+1 exp(M) + CtM/(1 − exp(−M)), which has properties similar to Pope's "cohort analysis" and is somewhat more accurate in the case of a continuous fishery, especially if the natural mortality rate (M) is large. Much closer simple approximations are possible if the seasonal pattern of catches is known.

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.

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.

Estimation of tag reporting rates in agestructured multicomponent fisheries where one component has observers

1999 ◽  
Vol 56 (7) ◽  
pp. 1255-1265 ◽  
Author(s):  
William S Hearn ◽  
Thomas Polacheck ◽  
Kenneth H Pollock ◽  
Wade Whitelaw
Keyword(s):  
Maximum Likelihood ◽  
Maximum Likelihood Estimators ◽  
Bluefin Tuna ◽  
Mortality Rates ◽  
Reporting Rate ◽  
Natural Mortality ◽  
Integrated Likelihood ◽  
Age Dependent ◽  
Southern Bluefin Tuna ◽  
Reporting Rates

For many tagging experiments, it is vital that fishers find and report all tags to scientists. If not, the tag reporting rate needs to be estimated so that fishing and natural mortality rates can be estimated. One way to estimate this rate is to have one fishery component (e.g., with observers) report every tag found from all fish that it catches. If the numbers of fish caught by all fishery components are also known and the tagged fish are mixed with the population (or subpopulation) being harvested, then one can estimate the reporting rate of underreporting fishery components. This procedure can fail if data are pooled over ages. We obtain maximum likelihood estimators for the reporting rate for each age and (or) each fishery component. We show how to estimate reporting rates if mixing of tagged and untagged fish occurs with some delay. We also obtain overall age-dependent reporting rates, which combine reporting rates from all components of the fishery. Our likelihood is part of an integrated likelihood that allows estimation of age-dependent fishing and natural mortalities in addition to the reporting rates. Our procedures are illustrated with some southern bluefin tuna (Thunnus maccoyii) tagging data.

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.

Age-specific natural mortality rates of adult Pacific herring (Clupea pallasi) from southern British Columbia

2000 ◽  
Vol 57 (11) ◽  
pp. 2258-2266 ◽  
Author(s):  
R W Tanasichuk
Keyword(s):  
British Columbia ◽  
Mortality Rate ◽  
Sampling Bias ◽  
Mortality Rates ◽  
Energy Requirements ◽  
Pacific Herring ◽  
Natural Mortality ◽  
Clupea Pallasi ◽  
Surplus Energy ◽  
Using Data

I used data for over 665 000 Pacific herring (Clupea pallasi) seined or gillnetted in southern British Columbia between 1951 and 1998 to estimate age- and year-specific adult natural mortality rates. Apparent sampling bias precluded using data collected before 1980. The instantaneous natural mortality rate is an increasing exponential function of age. Surplus energy requirements for gonad recrudescence appear to cause the death of adult herring.

Method of Solving for Natural Mortality Rate for Stock Components with Different Schedules of Growth and Mortality

1984 ◽  
Vol 41 (8) ◽  
pp. 1226-1230 ◽  
Author(s):  
J. F. Caddy
Keyword(s):  
Mortality Rate ◽  
Growth Rates ◽  
Total Mortality ◽  
Mortality Rates ◽  
Natural Mortality ◽  
Von Bertalanffy

A method is proposed for solving the natural mortality rates, MA and MB, for two stock components with different von Bertalanffy growth rates (KA and KB), where total mortality rates ZA and ZB are available for a series of years, and where the assumption of a constant M/K ratio can reasonably be made. The method has obvious applications for populations where the two sexes have different growth and mortality schedules, but have a constant relative availability to fishing.

Estimating exploitation rates of migrating yellowtail flounder (Limanda ferruginea) using multistate mark–recapture methods incorporating tag loss and variable reporting rates

2009 ◽  
Vol 66 (8) ◽  
pp. 1245-1255 ◽  
Author(s):  
Laura Cowen ◽  
Stephen John Walsh ◽  
Carl James Schwarz ◽  
Noel Cadigan ◽  
Joanne Morgan
Keyword(s):  
Mortality Rates ◽  
Assessment Model ◽  
Natural Mortality ◽  
Mark Recapture ◽  
Yellowtail Flounder ◽  
Limanda Ferruginea ◽  
Tag Loss ◽  
Model Migration ◽  
Reporting Rates ◽  
Mortality Estimates

Multistate mark–recapture models can be used to model migration through stratification of the study area into states (location). However, the incorporation of both tag loss and reporting rates is new to the multistate paradigm. We develop a migration model for fish that incorporates tag loss and reporting rates but has as its primary purpose the modelling of exploitation and natural mortality rates. This model is applied to a 2000–2004 yellowtail flounder ( Limanda ferruginea ) tagging study on the Grand Bank of Newfoundland, Canada. We found that exploitation rates varied over both location and years, ranging from 0.000 to 0.047. Migration into the centre of the Grand Bank (state 2) was three times higher than migration out. The estimate of the instantaneous annual natural mortality rate was 0.256, which is equivalent to an annual survival rate of 0.880. We describe how these mortality estimates will be quite valuable in specifying an assessment model for this stock.

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.

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