Possible recruitment of jack mackerel (Trachurus murphyi) from oceanic waters off Chile to the stock in Peruvian and

Ecuadorian waters in 2010

Ad CortenNetherlands Ministry of Economic Affairs / Pelagic

Freezertrawler Association

120°W

120°W

110°W

110°W

100°W

100°W

090°W

090°W

080°W

080°W

40°S 40°S

Distribution of catches of juvenile jack mackerel < 25 cm (yellow squares) by the PFA fleet during the 2010 fishing season compared to catches of larger jack mackerel (red squares)

05

101520

15 17 19 21 23 25 27 29 31 33 35 37 39 41 43 45 47 49 51 53 55

2007

05

101520

15 17 19 21 23 25 27 29 31 33 35 37 39 41 43 45 47 49 51 53 55

2008

05

101520

15 17 19 21 23 25 27 29 31 33 35 37 39 41 43 45 47 49 51 53 55

2009

05

101520

15 17 19 21 23 25 27 29 31 33 35 37 39 41 43 45 47 49 51 53 55

2010

05

101520

15 17 19 21 23 25 27 29 31 33 35 37 39 41 43 45 47 49 51 53 55

2011

05

101520

15 17 19 21 23 25 27 29 31 33 35 37 39 41 43 45 47 49 51 53 55

2013

05

101520

15 17 19 21 23 25 27 29 31 33 35 37 39 41 43 45 47 49 51 53 55

2012no observations

Length distribution of PFA catches from 2007 – 2013

2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 20130

200

400

600

800

PeruEcuador

thou

sand

tonn

es

2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 20130

200400600800

10001200140016001800

ChileEU

thou

sand

tonn

es

Catches of jack mackerel by country

Peru

Ecuador0°

10°

20°

30°

40°

50°

80°90° 70°100°110° 60°

South Pacific Current

Humboldt Current

Chile

Presumed pathway of juvenile jack mackerel from June to December 2010

10 15 20 25 30 35 40 45 50Total Length (cm)

Aug 2010

Nov 2010

Dec 2010

Jan 2011

Feb

Mar

Apr May

Jul

Oct

Dec

Sep

Jun

Aug

Feb

Apr

Jan 2012

Mar

length distribution of commercial catches in Peru in November 2010 – April 2012

15 17 19 21 23 25 27 29 31 33 35 37 39 41 43 45 47 49 51 53 550

5

10

15

20

25

30

35

40

length distribution of jack mackerel catches in Ecuador in February 2011

may

-10

jun-

10ju

l-10

aug-

10se

p-10

oct-

10no

v-10

dec-

10ja

n-11

feb-

11m

ar-1

1ap

r-11

may

-11

jun-

11ju

l-11

aug-

11se

p-11

oct-

11no

v-11

dec-

11ja

n-12

feb-

12m

ar-1

2ap

r-12

0

5

10

15

20

25

30

35

40

tota

l len

gth

EU catches in central Pacific

catches Peruvian fleet

Time axis with modal length of juvenile jack mackerel in central Pacific (June 2010) and modal length in Peruvian catches (November 2010 – April 2012). All measurements in total length

Peru

Ecuador0°

10°

20°

30°

40°

50°

80°90° 70°100°110° 60°

South Pacific Current

Humboldt Current

Chile

Presumed pathway of juvenile jack mackerel from June to December 2010

Positive SST anomalies in eastern Pacific in April 2010 illustrate the existence of an El Niño in the first half of 2010

Strong negative SST anomalies in the eastern Pacific in September 2010 illustrate the existence of a La Niña in the second half of the year

Suitable habitats for jack mackerel in the south-eastern Pacific

Classical scheme of juvenile jack mackerel migrations off Chile. From Arcos et al. 2001

Flota Peruana

Flota Chilena

ZE

ZE

ZC

15ºC

15ºC

Recent model for migrations of juvenile jack mackerel in the south-eastern Pacific. From Gretchina et al. 2007

Distribution of juveniles (red cloud) off Chile in a normal year (left) and in an El Niño year (right). From Gretchina et al. 2007.

Chilean juveniles may be adopted by the Peruvian population

• “Adopted Migrant” hypothesis (McQuinn 1997)

• Pelagic fish develop an attachment to the area where they happen to be at the time they turn into adults

• In this way, juveniles from Chilean origin may turn into “Peruvian” jack mackerel with biological characteristics similar to the Peruvian population

Conclusions

• Immigration of juveniles from Chile into Peru are likely to happen during La Niña periods

• A strong La Niña occurred in the second half of 2010

• This may have resulted in a transport of juveniles of year- class 2008 from Chile to Peru at this time

• The Chilean juveniles may have been “adopted” by the Peruvian population

• The occasional immigration of juveniles from Chile into Peru would explain the lack of genetic difference between the population in both areas