Access

You are not currently logged in.

Access your personal account or get JSTOR access through your library or other institution:

login

Log in to your personal account or through your institution.

If You Use a Screen Reader

This content is available through Read Online (Free) program, which relies on page scans. Since scans are not currently available to screen readers, please contact JSTOR User Support for access. We'll provide a PDF copy for your screen reader.

The Analysis of a Catch Curve

D. G. Chapman and D. S. Robson
Biometrics
Vol. 16, No. 3 (Sep., 1960), pp. 354-368
DOI: 10.2307/2527687
Stable URL: http://www.jstor.org/stable/2527687
Page Count: 15
  • Read Online (Free)
  • Download ($14.00)
  • Subscribe ($19.50)
  • Cite this Item
Since scans are not currently available to screen readers, please contact JSTOR User Support for access. We'll provide a PDF copy for your screen reader.
The Analysis of a Catch Curve
Preview not available

Abstract

The age distribution of a random sample, or the "catch curve" from a stationary animal or fish population, provides information on the annual survival rate of the population. The usual assumptions imply that the age distribution in such a population is geometric. The best (minimum variance unbiased) estimate of the annual survival rate is X̄[1 + X̄ - (1/n)]-1, X̄ being the mean age and n the sample size. This estimate is compared to the so-called "Jackson" estimate and some modifications of Jackson's estimate. Assumptions basic to regression estimates of the survival rate are considered. A test of the model is given for the particular case where it is suspected that there may be selection against younger ages. With the geometric age distribution there is no unbiased estimate of i, the instantaneous mortality rate, but a nearly unbiased estimate is given by i* = ln [1 + X̄ - (1/n)] - ln X̄ - [(n - 1)(n - 2)/n(t + 1)(n + t - 1)] where t = nX̄.

Page Thumbnails

  • Thumbnail: Page 
354
    354
  • Thumbnail: Page 
355
    355
  • Thumbnail: Page 
356
    356
  • Thumbnail: Page 
357
    357
  • Thumbnail: Page 
358
    358
  • Thumbnail: Page 
359
    359
  • Thumbnail: Page 
360
    360
  • Thumbnail: Page 
361
    361
  • Thumbnail: Page 
362
    362
  • Thumbnail: Page 
363
    363
  • Thumbnail: Page 
364
    364
  • Thumbnail: Page 
365
    365
  • Thumbnail: Page 
366
    366
  • Thumbnail: Page 
367
    367
  • Thumbnail: Page 
368
    368