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Age and Growth Program

PRECISION STATISTICS - 1990 TO 2006*

 

 

 

 


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     Click on the species name for age specific precision statistics or click here to download an Excel File.

     Before using any data from our website please read our disclaimer.

Scientific Name

Common Name

Number Aged

Number Tested

Percent Tested

Average Age

Percent Agreement

Percent CV

Percent APE

ANOPLOPOMA FIMBRIA

SABLEFISH (BLACK COD)

35917

8052

22.4

10.4

37.9

10.83

7.66

ATHERESTHES EVERMANNI

KAMCHATKA FLOUNDER

120

24

20.0

8.93

41.7

9.23

6.53

ATHERESTHES STOMIAS

ARROWTOOTH FLOUNDER

9761

2487

25.5

6.55

50.1

8.37

5.92

GADUS MACROCEPHALUS

PACIFIC COD

24057

7531

31.3

4.76

58.7

7.74

5.47

GLYPTOCEPHALUS ZACHIRUS

REX SOLE

2079

423

20.3

7.48

48.0

8.76

6.19

HIPPOGLOSSOIDES ELASSODON

FLATHEAD SOLE

9713

2655

27.3

10.06

42.1

7.09

5.01

HIPPOGLOSSOIDES ROBUSTUS

BERING FLOUNDER

237

48

20.3

8.61

79.2

1.94

1.37

LEPIDOPSETTA BILINEATA

ROCK SOLE

7802

1698

21.8

8.39

68.9

3.19

2.26

LEPIDOPSETTA BILINEATA

SOUTHERN ROCK SOLE

482

101

21.0

10.16

53.5

5.43

3.84

LEPIDOPSETTA PERACUATA

NORTHERN ROCK SOLE

8559

2902

33.9

10.57

66.7

2.94

2.08

LIMANDA ASPERA

YELLOWFIN SOLE

21046

5643

26.8

12.54

62.7

2.89

2.04

MERLUCCIUS PRODUCTUS

PACIFIC WHITING

47916

14150

29.5

6.3

76.8

4.16

2.94

MICROSTOMUS PACIFICUS

DOVER SOLE

3601

848

23.5

18.53

21.6

10.64

7.52

MYOXOCEPHALUS POLYACANTHOCEPHALUS

GREAT SCULPIN

403

245

60.8

6.94

60.0

6.78

4.79

PLEUROGRAMMUS MONOPTERYGIUS

ATKA MACKEREL

22786

5435

23.8

4.07

84.0

2.72

1.92

PLEURONECTES QUADRITUBERCULATUS

ALASKA PLAICE

3679

815

22.2

13.22

61.7

2.91

2.05

REINHARDTIUS HIPPOGLOSSOIDES

GREENLAND TURBOT

169

55

32.5

12.01

29.1

6.71

4.75

SEBASTES ALEUTIANUS

ROUGHEYE ROCKFISH

7234

2312

32.0

23.3

25.0

8.11

5.74

SEBASTES ALUTUS

PACIFIC OCEAN PERCH

26189

8087

30.9

12.98

41.1

6.37

4.50

SEBASTES CILIATUS

DARK ROCKFISH

1881

739

39.3

18.56

48.7

3.48

2.46

SEBASTES POLYSPINIS

NORTHERN ROCKFISH

11994

2852

23.8

16.49

44.4

4.13

2.92

SEBASTES VARIABILIS

DUSKY ROCKFISH

4692

1186

25.3

13.37

55.8

3.18

2.25

SEBASTES VARIEGATUS

HARLEQUIN ROCKFISH

647

501

77.4

12.69

51.7

4.23

2.99

SEBASTES ZACENTRUS

SHARPCHIN ROCKFISH

570

154

27.0

12.57

40.3

6.51

4.60

THERAGRA CHALCOGRAMMA

WALLEYE POLLOCK

202917

55282

27.2

6.35

66.8

4.40

3.11


 
 

Average age is the average of all fish aged.  Unageable and ranged samples were excluded. Samples may have been collected several years before data was released. Rock sole (Lepidopsetta bilineata) statistics are from samples collected before the species was split into southern rock sole (Lepidopsetta bilineata) and northern rock sole (Lepidopsetta peracuata).

Precision:  Between-reader precision generally refers to the repeatability of an age when two different age readers age the same fish, with no knowledge of the other reader's age. For these twice-aged fish, an age is available from the reader (r) and a more experienced tester (t). Three measures of statistical precision can be calculated from the between-reader ages:

1.  Percent Agreement (PA):

2. Average Percent Error (APE):

3. Coefficient of Variation (CV):

where n = the number of fish in the test sample and is the average age of a single fish.

APE and CV are averaged over all test samples. Often it is desirable to calculate PA, APE and CV broken down by age class. This is useful since precision estimates, especially PA, will vary with age. An advantage of both APE and CV is that they generally will not vary too much with age as they are scaled by

Kimura, D.K., and J.J. Lyons. 1991.  Between-reader bias and variability in the age-determination process. Fish. Bull., U.S. 89:53-60.

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