presented by : michael ballón
DESCRIPTION
Trends in relative investment of energy in growth and/or reproduction by Peruvian hake Merluccius gayi peruanus from 1972 – 2004: an issue of length dependence. Presented by : Michael Ballón. Instituto del Mar del Peru, Project INCOFISH. - PowerPoint PPT PresentationTRANSCRIPT
Trends in relative investment of energy in growth and/or reproduction by Peruvian hake Merluccius gayi peruanus from
1972 – 2004:an issue of length dependence
Authors: Michael Ballón, Claudia Wosnitza-Mendo, Arnaud Bertrand, Jacqueline Palacios, Humberto Olivera, and Renato Guevara-Carrasco
Presented by: Michael Ballón
Instituto del Mar del Peru,
Project INCOFISH
OVERVIEW
Introduction
Objective
Materials and Methods
Results and Discussion
Conclusions
Significance of hake• Distribution
Main factors that have affected the hake population
•sardine and anchovy regime•El Niño•Overfishing 40 cm 25 cm
Current situation•New regulations (2002) were set up based on a single species approach (IMARPE)•The stock still far from recovery•Why?
Introduction
82° W 80° W 78° W 76° W
12°S
10°S
8°S
6°S
4°S
Paita
C him bote
C allao
Objective
Main question: How has hake reacted physiologically to the fishing pressure and the physical environment?
Clarifying the effects.
Reducing uncertainty about:
Natural Mortality and Recruitment Success
Hake physiological responses
Materials and MethodsBiological data:
52106 Female hakes sampled from 1971-2004 from Paita port
Total body weight (W) Total length (L)Gonad weight (Wg) Stomach weight (Ws)
Biological Indices
Fulton's condition factor K = W.L-3
Gonadosomatic index GI = Wg.W-1
Fullness index FI = Ws.W-1
Physical environment and time
Paita sea surface temperature anomaly (SSTA) Year-Month (YM)
Time series (1971-2004)Condition factor Gonadosomatic index
0.004
0.024
0.044
0.064
0.084
0.104
0.124
0.144
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
years
mea
n co
nditi
on fa
ctor
0.005
0.0055
0.006
0.0065
0.007
0.0075
0.008
0.0085
0.009
0.0095
mea
n go
ndos
omat
ic in
dex
GI K
Results and Discussion…time series
0.004
0.024
0.044
0.064
0.084
0.104
0.124
0.144
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
years
mea
n co
nditi
on fa
ctor
0.005
0.0055
0.006
0.0065
0.007
0.0075
0.008
0.0085
0.009
0.0095
mea
n go
ndos
omat
ic in
dex
GI K
Long term
Upward trend in condition factor
Downward trend in reproduction activity
Results and Discussion…time series
Short term
Negative impact of El Niño
In both: Fish condition and reproduction
Results and Discussion…?
What are the factors that influence fish condition and maturation proccess?
Materials and MethodsBiological data:
52106 Female hakes sampled from 1971-2004 from Paita port
Total body weight (W) Total length (L)Gonad weight (Wg) Stomach weight (Ws)
Biological Indices
Fulton's condition factor K = W.L-3
Gonadosomatic index GI = Wg.W-1
Fullness index FI = Ws.W-1
Physical environment and time
Paita sea surface temperature anomaly (SSTA) Year-Month (YM)
Generalized Additive Model GAM (1980 -2004) Large hakes (35-50
cm) Small hakes (20-35 cm)
Condition factor K according to GI+FI+SSTA+YMGonadosomatic index GI according to K+FI+SSTA+YM
0.00 0.07 0.14 0.21 0.28 0.35
Fullness IndexFullness index
Results and Discussion…GAM models
Condition factor: K according to GI+FI+SSTA+YM
Large hake (35-50cm)Small hake (20-35cm)
0.00 0.05 0.10 0.15 0.20 0.25
Gonadosomatic Index
-0.0
005
0.00
10"C
ondi
tion
Fact
or"
Gonadosomatic index
“Con
diti
on f
acto
r”
Gonadosomatic Index: GI according to K+FI+SSTA+YM
0.0040 0.0055 0.0070 0.0085 0.0100Condition Factor
-0.0
60.
000.
06"G
onad
Inde
x"
0.0 0.1 0.2 0.3Fullness Index
During the spawning season there is a starving process.
Fecundity depends more on the initial condition factor than on the food intake during the spawning season.
Better condition
More food
Better condition
Higher FecundityStarving
-2 -1 0 1 2 3 4-0.0
012
-0.0
008
-0.0
004
0.00
00
-1 0 1 2 3 4
-0.0
15-0
.010
-0.0
050.
000
Results and Discussion…
“Con
ditio
n F
acto
r”
“Gon
ados
omat
ic in
dex”
Poor condition + spawning high mortalityLarge hake invest more energy in reproduction than small hakeLarge hake disappeared during the El Niño 1992-93 and 1997-98
Large
Small
Large
Small
SSTAnomaly SSTAnomaly
EL Niño
_
+
RESULTS and DISCUSSION…long term
1980 1985 1990 1995 2000 2005
Y M
-0.0
00
40
.00
00
0.0
00
4
s(Y
M)
-0.0
10
.00
0.0
10
.02
s(Y
M)
“Con
ditio
n fa
ctor
”
“Gon
ados
omat
ic in
dex”
Large hake (35-50 cm)
-0.0
15
-0.0
10
-0.0
05
0.0
00
0.0
05
s(Y
M)
1980 1985 1990 1995 2000 2005
Y M
-0.0
00
40
.00
00
0.0
00
4
s(Y
M)
Small hake (20-35 cm)
“Gon
ados
omat
ic in
dex”
“Con
ditio
n fa
ctor
”
?
Why small hake spent their energy reserves in reproduction and large hake do not, although the latter has a higher condition factor ?
RESULTS and DISCUSSION…long term
• Low reproduction could be expected when biomass is close to the carrying capacity level
HOWEVER
•hake biomass has been at a low level from the late 1990s onwards
•Size at first maturity has reduced in the last decades (recovering SSB)
AND at the same time large hake has reduced reproduction activity
That is not a logical density-dependent effect
Is this a density-dependent effect?
RESULTS and DISCUSSION…long term
0.0
0.2
0.4
0.6
0.8
1.0
89 91 93 95 97 99 01 03 05
0.0
0.2
0.4
0.6
0.8
1.0
80 82 84 86 88 90 92 94 96 98 00 02 04
0.0
0.2
0.4
0.6
0.8
1.0
95 97 99 01 03 05
35 +_ 2 cm
+_ 2 cm25
+_ 2 cm20
Fem
ale
prop
orti
on
Years
Female propotion estimated
from commertial landings Paita
•Sex proportion from 80% males to 80% females
•Lack of males for large hake ( >35 cm)
•Low fertilization rate
•Low stimulation for the spawning act
Conclusions