Age determination and validation on jack
mackerel in IFOP-Chile: a brief review
Rodolfo Serra
2nd Meeting of the Scientific Committee
South Pacific Regional Fisheries Management Organization
Honolulu, Hawaii, USA
1-7 October 2014
Instituto de Fomento Pesquero - Chile
Age readings in Chile
•
For the age determination the left whole otolith is used, which is submerged in a
Petri’s plate with black bottom, where the otolith is covered with transparent oil,
and read under a stereoscopic microscope with magnification of 10X and using
reflected light.
•
In fish, larger than 45 cm fork length a transversal section of the right otolith
is used, which is polished and toasted. The section reading is complementary to
the reading on the whole otolith to avoid bias in ageing the fish
Instituto de Fomento Pesquero - Chile
Jack Mackerel Age Validation
•
•
•
•
•
•
Age determination has been validated by the analysis of the border of the otolith
first by Aguayo et al., (1981) and also by other researchers.
Also through daily rings; the age-size relationship shows a strong agreement for
the two first ages in a work done by Araya et al. (1993).
Progression of Strong year-classes
Bomb Radiocarbon Analysis
The work done in Chile agrees with Nekrasov (1987) and Kochkin (1994) which
identify one growth ring per year.
Independent review of the Chilean jack mackerel age determination done by IFOP
by Dr. Beatriz Morales-Nin from the Instituto Mediterráneo de Estudios Avanzados,
Spain.
Instituto de Fomento Pesquero - Chile
Margin analysis following strong year-classes
From Gili, Bocic and Serra,
1995.
Instituto de Fomento Pesquero - Chile
Progression of Strong year-classes
1500000
600000
25
1000000
500000
1987
1977
52
57
62
1978
52
57
62
1979
52
57
2
3
4
5
6
7
8
9 10 11 12 13 14 15 16 17 18 19 20
0
12
28
2000000
1500000
1000000
500000
0
2
3
4
5
3000000
6
7
8
9 10 11 12 13 14 15 16 17 18 19 20
31
2000000
1000000
1989
0
0
1
2
3
4
5
6
7
8
9 10 11 12 13 14 15 16 17 18 19 20
35
2000000
1500000
1000000
500000
0
1990
0
1
2
3
4
5
6
7
8
9 10 11 12 13 14 15 16 17 18 19 20
37
2000000
1500000
1000000
500000
0
1991
0
1
2
3
4
5
6
7
8
9 10 11 12 13 14 15 16 17 18 19 20
1500000
12
17
3
4
5
6
7
8
22
42
47
52
57
62
27
32
37
42
47
52
57
62
1989
12
17
22
27
32
800000
600000
400000
200000
0
37
42
47
52
57
62
34
1990
12
17
22
27
32
37
42
47
52
57
62
37
800000
600000
400000
200000
0
1991
12
17
22
27
32
37
42
Fork Length
9 10 11 12 13 14 15 16 17 18 19 20
From Cerna and Bocic, 2011
Instituto de Fomento Pesquero - Chile
47
52
57
62
0
1
2
0
1
2
0
1
2
0
1
2
0
1
2
2000000
1500000
1000000
500000
0
30-31
800000
600000
400000
200000
0
1992
2
37
1988
0
1
32
0
1000000
500000
27
27
Age Group
0
22
500000
3
1
17
1000000
1988
0
62
1000000
Numero de ejemplares (10^3)
62
1
Number
of Fish
(x10 )
Numero de
ejemplares
(10^3)
3
Number of(10^3)
Fish (x10 )
Numero de ejemplares
57
2000000
1987
0
0
52
3000000
200000
0
1976
24
400000
2000000
1500000
1000000
500000
0
1500000
1000000
500000
0
1500000
1000000
500000
0
Bomb Radiocarbon Analysis
16
CV = 0,072
n = 21
15
Whole Otolith Ageing
14
13
12
11
10
9
8
7
6
5
4
4
5
6
7
8
9
10
11
12
14
Age C
From: Cerna and Bocic. 2011.
Instituto de Fomento Pesquero - Chile
13
14
15
16
Main conclusions of the Otolith Interpretation and Aging
Workshop held in 2011
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The results of the age reading exercises show particularly good agreement when
ageing otoliths of juveniles.
In juveniles it is far easier to identify the 1st and 2nd ring, although it is not always
possible to do so.
For fish up to about age 11 there are reasonably high levels of agreement between
readers. However, there are still high CVs on age readings, and statistically
significant differences between readers.
In older fish, and particularly using whole otoliths, it is frequently difficult to
identify the first one or two rings, and this then affects age readings for
subsequent rings.
Use of otolith sections results in better ageing of larger fish (> 40 cm FL) than using
whole otoliths.
Instituto de Fomento Pesquero - Chile
References
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Aguayo, M., E. Estay and V. Ojeda. 1981. Determinación de la edad y crecimiento
del jurel (Trachurus symmetricus murphyi) en la zona Arica-Coquimbo y
Talcahuano. Informe Técnico. IFOP/SUBPESCA. 88 págs.
Araya, M., M. Medina and H. Arancibia. 1993. Edad y crecimiento del jurel
Trachurus murphyi de la zona centro sr de Chile mediante el método de lectura de
micro-incrementos diarios de los otolitos y confección de claves talla/edad.
Informe Final. Departamento Ciencias del Mar. Universidad Arturo Prat, Iquique,
Chile. 72 p.
Cerna, F. and V. Bocic. 2011. Age validation and growth function of Chilean jack
mackerel (Trachurus murphyi) off Chile. Document presented at the Chilean jack
mackerel Otolith Interpretation and Ageing Workshop. Lima, Peru. July, 2011.
Gili, R., V. Bocic and R. Serra. 1995. Análisis de la periodicidad de formación del
anillo hialino en otolitos de jurel de la costa e Chile. Informe Técnico Interno. IFOP.
Kochkin. P.N. 1994. Age determination and estimates of growth rate for the
Peruvian jack mackerel, Trachurus symmetricus murphyi. J. Ichth. 34(3): 39-50Instituto de Fomento Pesquero - Chile
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Age determination and validation on jack mackerel in IFOP