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Accuracy and Precision of Fish Ages - Northeast

January 05, 2021

It is important to ensure consistency in fish ages used in fish population assessments. The Fishery Biology Program in the Northeast conducts age and growth studies and completes regular testing to provide measures of consistency and accuracy.

Fishery Biology Program staff regularly test themselves to ensure their ages are precise and accurate. This table summarizes the results of precision testing for 2016–2020. Full information is linked above. 

Species

Number of Tests

Number of Fish Aged

Number of Fish Tested

CV (%)

Agreement (%)

Bass, Black Sea

27

15,617

2,154

2.40

86.6

Bluefish

7

2,173

439

2.48

89.3

Butterfish

15

8,237

993

4.32

88.1

Cod, Atlantic

30

24,847

2,356

0.13

99.5

Flounder, Summer

29

17,300

2,440

1.86

89.5

Flounder, Windowpane

2

585

100

6.85

74.4

Flounder, Winter 

19

9,139

1,628

2.02

86.3

Flounder, Witch

29

8,904

1,903

1.40

86.4

Flounder, Yellowtail

38

15,771

2,663

1.79

90.7

Haddock

28

35,182

2,611

0.42

97.2

Hake, Red

10

7,658

906

2.82

87.2

Hake, Silver

30

23,823

2,525

1.60

94.1

Hake, White

20

5,561

1,076

2.29

92.7

Herring, Atlantic

11

7,295

1,002

0.93

92.4

Mackerel, Atlantic

19

7,618

1,400

0.77

97.5

Plaice, American

25

13,888

2,195

4.10

67.3

Pollock

23

9,551

1,681

0.39

96.2

Redfish, Acadian

9

5,557

762

1.95

72.9

Scup

19

10,524

1,628

3.73

79.1

Surfclam, Atlantic

1

659

94

0.43

95.7

Tilefish, Golden

11

5,823

915

3.01

75.5

 

Agreement: the percentage of fish where the two ages matched. A perfect result is 100 percent; over 80 percent is acceptable. 

CV: a statistic which accounts for the relative difference between ages. A perfect result is 0 percent; under 5 percent is acceptable.

Last updated by Northeast Fisheries Science Center on 04/13/2021

Age and Growth Age and Growth Program Otolith