A new way to estimate the age of bowhead whales (Balaena mysticetus) using ovarian corpora counts

2011 ◽  
Vol 89 (9) ◽  
pp. 840-852 ◽  
Author(s):  
J.C. George ◽  
E. Follmann ◽  
J. Zeh ◽  
M. Sousa ◽  
R. Tarpley ◽  
...  
Keyword(s):  
Corpus Luteum ◽  
Pregnancy Rate ◽  
Sexual Maturity ◽  
Standard Errors ◽  
Reproductive Parameters ◽  
Balaena Mysticetus ◽  
Bowhead Whales ◽  
Aspartic Acid Racemization ◽  
Sexually Mature ◽  
Age Estimates

We used lengths and reproductive data for bowhead whales ( Balaena mysticetus L., 1758) harvested by Alaskan Eskimos to estimate female reproductive parameters and age. Data from 117 females determined that 75 were sexually mature and 42 were immature. Estimated length at sexual maturity was 13.35 m. Counts of ovarian corpora were obtained from 50 mature females. Corpora and baleen data were used with aspartic acid racemization (AAR) data to obtain estimated age at sexual maturity (ASM) at ≈26 years. The number of corpora counted in both ovaries (or estimated when only one ovary was counted) was used with ASM and estimated ovulation rate (OR) to obtain corpora age estimates ranging from 26 to 149 years. A stone harpoon tip recovered from whale 92B2 was consistent with her corpora age of 133 years. The correlation between corpora and AAR age estimates was 0.77. Estimated standard errors of corpora ages tended to be somewhat higher than those for comparable AAR ages. A sample of potentially mature females examined for maturity and presence of a corpus luteum and (or) fetus provided an OR value of 0.332·year–1 and an estimated pregnancy rate of 0.326·year–1, implying intervals between ovulations and pregnancies of 3.0 and 3.1 years.

Age and growth estimates of bowhead whales (Balaena mysticetus) via aspartic acid racemization

1999 ◽  
Vol 77 (4) ◽  
pp. 571-580 ◽  
Author(s):  
John C George ◽  
Jeffrey Bada ◽  
Judith Zeh ◽  
Laura Scott ◽  
Stephen E Brown ◽  
...  
Keyword(s):  
Aspartic Acid ◽  
Standard Error ◽  
Sexual Maturity ◽  
Delta Method ◽  
Age And Growth ◽  
Eye Lens ◽  
Bowhead Whales ◽  
Aspartic Acid Racemization ◽  
Coefficients Of Variation ◽  
Age Estimates

A total of 48 eye globes were collected and analyzed to estimate ages of bowhead whales using the aspartic acid racemization technique. In this technique, age is estimated based on intrinsic changes in the D and L enantiomeric isomeric forms of aspartic acid in the eye lens nucleus. Age estimates were successful for 42 animals. Racemization rate (kAsp) for aspartic acid was based on data from earlier studies of humans and fin whales; the estimate used was 1.18 10-3/year. The D/L ratio at birth ((D/L)0) was estimated using animals less than or equal to 2 years of age (n = 8), since variability in the D/L measurements is large enough that differences among ages in this range are unmeasurable. The (D/L)0 estimate was 0.0285. Variance of the age estimates was obtained using the delta method. Based on these data, growth appears faster for females than males, and age at sexual maturity (age at length 12-13 m for males and 13-13.5 m for females) occurs at around 25 years of age. Growth slows markedly for both sexes at roughly 40-50 years of age. Four individuals (all males) exceed 100 years of age. Standard error increased with estimated age, but the age estimates had lower coefficients of variation for older animals. Recoveries of traditional whale-hunting tools from five recently harvested whales also suggest life-spans in excess of 100 years of age in some cases.

Age and growth estimates of bowhead whales (Balaena mysticetus) via aspartic acid racemization

1999 ◽  
Vol 77 (4) ◽  
pp. 571-580 ◽  
Author(s):  
John C. George ◽  
Jeffrey Bada ◽  
Judith Zeh ◽  
Laura Scott ◽  
Stephen E. Brown ◽  
...  
Keyword(s):  
Aspartic Acid ◽  
Age And Growth ◽  
Balaena Mysticetus ◽  
Bowhead Whales ◽  
Aspartic Acid Racemization

Age estimation for young bowhead whales (Balaena mysticetus) using annual baleen growth increments

2008 ◽  
Vol 86 (6) ◽  
pp. 525-538 ◽  
Author(s):  
S. C. Lubetkin ◽  
J. E. Zeh ◽  
C. Rosa ◽  
J. C. George
Keyword(s):  
Growth Parameters ◽  
Age Determination ◽  
Population Level ◽  
Exponential Model ◽  
Growth Increment ◽  
Balaena Mysticetus ◽  
Nonlinear Mixed Effects Model ◽  
Bowhead Whales ◽  
Growth Increments ◽  
Age Estimates

We compiled age estimates and baleen plate δ13C data from 86 bowhead whales ( Balaena mysticetus L., 1758). We used previous whale age estimates based on aspartic acid racemization (AAR) and corpora counts to extend the use of δ13C data for age determination from cycle counting to a modified exponential model using annual baleen growth increments. Our approach used the growth increment data from individual whales in a nonlinear mixed effects model to assess both population-level and whale-specific growth parameters. Although age estimates from baleen-based models become less precise as the whales age, and baleen growth and length near steady state, the growth increment model shows promise in estimating ages of bowhead whales 10–13.5 m long with baleen lengths <250 cm, where other techniques are less precise or the data are scarce. Ages estimated using the growth increment data from such whales ranged from 6.4 to 19.8 years.

Statistical modeling of baleen and body length at age in bowhead whales (Balaena mysticetus)

2012 ◽  
Vol 90 (8) ◽  
pp. 915-931 ◽  
Author(s):  
S.C. Lubetkin ◽  
J.E. Zeh ◽  
J.C. George
Keyword(s):  
Body Length ◽  
Growth Model ◽  
Growth Models ◽  
Information Criterion ◽  
Single Stage ◽  
Von Bertalanffy ◽  
Balaena Mysticetus ◽  
Bowhead Whales ◽  
Multi Stage ◽  
Age Estimates

We used baleen lengths and age estimates from 175 whales and body lengths and age estimates from 205 whales to test which of several single- and multi-stage growth models best characterized age-specific baleen and body lengths for bowhead whales ( Balaena mysticetus L., 1758) with the goal of determining which would be best for predicting whale age based on baleen or body length. Previous age estimates were compiled from several techniques, each of which is valid over a relatively limited set of physical characteristics. The best fitting single-stage growth model was a variation of the von Bertalanffy growth model for both baleen and body length data. Based on Bayesian information criterion, the two- and three-stage versions of the von Bertalanffy model fit the data better than did the single-stage models for both baleen and body length. The best baleen length models can be used to estimate expected ages for bowhead whales with up to 300–325 cm baleen, depending on sex, which correspond to age estimates approaching 60 years. The best body length models can be used to estimate expected ages for male bowhead whales up to 14 m, and female bowheads up to 15.5 m or ages up to approximately 40 years.

Biological Parameters of the Antarctic Minke Whale at the Virginal Population Level

1975 ◽  
Vol 32 (7) ◽  
pp. 995-1004 ◽  
Author(s):  
Seiji Ohsumi ◽  
Yasuaki Masaki
Keyword(s):  
Sex Ratio ◽  
Pregnancy Rate ◽  
Sexual Maturity ◽  
Population Level ◽  
Testis Weight ◽  
Natural Mortality ◽  
Biological Parameters ◽  
Antarctic Minke Whale ◽  
The Antarctic ◽  
Sexually Mature

New data from Japanese catches in Antarctic seasons 1971–72 and 1972–73 are used to calculate biological parameters. Determinations are: fetal sex ratio (52.0% females); sex ratio in catch (54.1% females); [Formula: see text], males (27.9 ft), females (29.5 ft); age at asymptotic body length, males (18–20 yr), females (20–22 yr); male sexual maturity at testis weight (0.4 kg); length at beginning of sexual maturity, males (21 ft), females (24 ft) and at 50% sexually mature, males (23.6 ft), females (26.2 ft); age at sexual maturity, females (6 yr); apparent pregnancy rate (89.5%); annual ovulation rate (0.866); litter size (1.007); natural mortality coefficient of sexually mature sample (0.127) and of sexually immature sample (0.213); age at recruitment (6 yr); and rate of recruitment in virgin population (0.119).

I.—On the Pregnancy Rate in the Lactating Mouse and the Effect of Suckling on the Duration of Pregnancy

1932 ◽  
Vol 51 ◽  
pp. 1-7 ◽  
Author(s):  
L. Mirskaia ◽  
F. A. E. Crew
Keyword(s):  
Mammary Gland ◽  
Corpus Luteum ◽  
Pregnancy Rate ◽  
Inhibitory Action ◽  
Reproductive Activity ◽  
Delayed Implantation ◽  
Prolonged Pregnancy ◽  
Suggested Explanation ◽  
Duration Of Pregnancy

Summary1. The pregnancy rate of primiparæ, suckling their young, was, in this experiment, 24·1 per cent.; that of multiparæ suckling their young, 50 per cent. It is shown that this difference is not due to differences in the incidence of ovulation associated with postpartum œstrus. The suggested explanation of this difference between puberal and adult groups is that a certain level of somatic maturity is a prerequisite for full reproductive activity.2. In all cases the duration of pregnancy was prolonged. The degree of prolongation was variable and could not be related to the number of young in the uterus or suckling. The results provide no support for the suggestion that this prolongation, due to delayed implantation of the fertilised ova, is to be referred to an inhibitory action on the part of the mammary gland. The suggestion is made that the delayed implantation and prolonged pregnancy are due to inability on the part of the corpus luteum to cater adequately for implantation and lactation synchronously.

scholarly journals Reproductive Biology of Round Sardinella (Sardinella Aurita) (Valenciennes, 1847) in Senegalese Coastal Waters

2018 ◽  
Vol 9 (1) ◽  
pp. 31
Author(s):  
Ismaïla NDIAYE ◽  
Alassane SARR ◽  
Alioune FAYE ◽  
Modou THIAW ◽  
Malick DIOUF ◽  
...  
Keyword(s):  
Sex Ratio ◽  
Reproductive Biology ◽  
Coastal Waters ◽  
Sexual Maturity ◽  
Reproductive Parameters ◽  
Monthly Variation ◽  
Relative Fecundity ◽  
The Mean ◽  
Sardinella Aurita ◽  
Somatic Index

In this study, a total of 1068 specimens Sardinella aurita of which 553 females and 515 males were examined. The objectif of this study was to determine the reproductive parameters of Sardinella aurita. The sex ratio was significantly in favor of females (55%). The size at first sexual maturity was estimated at 18.9 cm for females and 18.0 cm for males. The monthly variation of sexual maturity stages and gonado-somatic index (GSI) allowed to locate the reproduction periods from February to June and from September to December. The mean absolute fecundity was estimated at 110.794 ± 7582 oocytes whereas relative fecundity was about 422 ± 26 oocytes per gram of female.

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