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Transcript of Spatial and temporal variability in Atka mackerel (Pleurogrammus monopterygius) female maturity at...
![Page 1: Spatial and temporal variability in Atka mackerel (Pleurogrammus monopterygius) female maturity at length and age. A component of NPRB project 0522: Reproductive.](https://reader030.fdocuments.net/reader030/viewer/2022033023/56649cc05503460f94987833/html5/thumbnails/1.jpg)
Spatial and temporal variability in Atka mackerel (Pleurogrammus
monopterygius) female maturity at length and age.
A component of NPRB project 0522: Reproductive ecology of Atka mackerel, Pleurogrammus
monopterygius, in Alaska.
Daniel Cooper and Susanne McDermott Fisheries Interaction
Team (FIT), AFSCJames Ianelli, AFSC, SSMA
![Page 2: Spatial and temporal variability in Atka mackerel (Pleurogrammus monopterygius) female maturity at length and age. A component of NPRB project 0522: Reproductive.](https://reader030.fdocuments.net/reader030/viewer/2022033023/56649cc05503460f94987833/html5/thumbnails/2.jpg)
Introduction
• Maturity at age/length used to estimate spawning biomass
• Maturity varies temporally and spatially in some other species– Growth differences
• Temperature• Population density
– Decreases caused by fishing pressure
• Maturity estimates in ecological studies
![Page 3: Spatial and temporal variability in Atka mackerel (Pleurogrammus monopterygius) female maturity at length and age. A component of NPRB project 0522: Reproductive.](https://reader030.fdocuments.net/reader030/viewer/2022033023/56649cc05503460f94987833/html5/thumbnails/3.jpg)
Introduction – Atka mackerel maturity
• Previous Atka mackerel maturity estimates (McDermott and Lowe 1997)– Maturity at age constant (Age 50% maturity ~3.6
years– Maturity at length decreases from East to West– Atka mackerel growth decreases from East to West– Growth differences hypothesized to explain spatial
maturity differences
• Temporal maturity variability unknown• Some strong year classes
![Page 4: Spatial and temporal variability in Atka mackerel (Pleurogrammus monopterygius) female maturity at length and age. A component of NPRB project 0522: Reproductive.](https://reader030.fdocuments.net/reader030/viewer/2022033023/56649cc05503460f94987833/html5/thumbnails/4.jpg)
Questions
1. Does maturity vary spatially and/or temporally?
2. Is maturity determined by length or age?
3. Does growth affect maturity?
4. How do large year classes affect maturity?
![Page 5: Spatial and temporal variability in Atka mackerel (Pleurogrammus monopterygius) female maturity at length and age. A component of NPRB project 0522: Reproductive.](https://reader030.fdocuments.net/reader030/viewer/2022033023/56649cc05503460f94987833/html5/thumbnails/5.jpg)
EastWest
Collection sites
No genetic difference found using microsatellites(Ingrid Spies, AFSC, unpublished data)
![Page 6: Spatial and temporal variability in Atka mackerel (Pleurogrammus monopterygius) female maturity at length and age. A component of NPRB project 0522: Reproductive.](https://reader030.fdocuments.net/reader030/viewer/2022033023/56649cc05503460f94987833/html5/thumbnails/6.jpg)
Methods – New Data
• Platform was tag recovery cruises East: 2002, 2003, 2004
West: 2002, 2003
• Ovaries from 5 females randomly collected per trawl haul
• Histology completed
• Fish aged by AFSC age and growth program
![Page 7: Spatial and temporal variability in Atka mackerel (Pleurogrammus monopterygius) female maturity at length and age. A component of NPRB project 0522: Reproductive.](https://reader030.fdocuments.net/reader030/viewer/2022033023/56649cc05503460f94987833/html5/thumbnails/7.jpg)
Methods (cont.)
• Maturity determined using histology plus visual ID of remnant ova
• Maturity determined for some females from presence of POFs* alone (Saborido-Rey and Junquera 1998, Narimatsu et al. 2005)
*Post-Ovulatory Follicles
![Page 8: Spatial and temporal variability in Atka mackerel (Pleurogrammus monopterygius) female maturity at length and age. A component of NPRB project 0522: Reproductive.](https://reader030.fdocuments.net/reader030/viewer/2022033023/56649cc05503460f94987833/html5/thumbnails/8.jpg)
Remnant ovapersist at least one year (Not present in all mature females)
Remnant Ova and POF
Post-ovulatory follicle(unknown persistance time)
![Page 9: Spatial and temporal variability in Atka mackerel (Pleurogrammus monopterygius) female maturity at length and age. A component of NPRB project 0522: Reproductive.](https://reader030.fdocuments.net/reader030/viewer/2022033023/56649cc05503460f94987833/html5/thumbnails/9.jpg)
Methods (Cont.)
• GLM applied geographic area and time period as factors
Where Y = Proportion mature, x = length or age, α,β are parameters
• Chi-squared approximation used to test significance of GLM terms
)(1
1xe
Y
![Page 10: Spatial and temporal variability in Atka mackerel (Pleurogrammus monopterygius) female maturity at length and age. A component of NPRB project 0522: Reproductive.](https://reader030.fdocuments.net/reader030/viewer/2022033023/56649cc05503460f94987833/html5/thumbnails/10.jpg)
Results: Maturity at age
0
0.5
1
2 3 4 5 6 7 8 9 10 11 12 13 14
East dataWest dataCombined expected
Area not significant p=0.4
Age (years)
Pro
port
ion
mat
ure
![Page 11: Spatial and temporal variability in Atka mackerel (Pleurogrammus monopterygius) female maturity at length and age. A component of NPRB project 0522: Reproductive.](https://reader030.fdocuments.net/reader030/viewer/2022033023/56649cc05503460f94987833/html5/thumbnails/11.jpg)
Results: Maturity at length by area
0
0.5
1
20 25 30 35 40 45 50
East data
East expected
West data
West expected
Fork length (cm)
Pro
port
ion
mat
ure
Area significant, p<<0.0001
![Page 12: Spatial and temporal variability in Atka mackerel (Pleurogrammus monopterygius) female maturity at length and age. A component of NPRB project 0522: Reproductive.](https://reader030.fdocuments.net/reader030/viewer/2022033023/56649cc05503460f94987833/html5/thumbnails/12.jpg)
Maturity at length by age
0
0.5
1
25 30 35 40 45 50
Fork length (cm)
Pro
port
ion
mat
ure
3 Year olds
4+ Year olds
![Page 13: Spatial and temporal variability in Atka mackerel (Pleurogrammus monopterygius) female maturity at length and age. A component of NPRB project 0522: Reproductive.](https://reader030.fdocuments.net/reader030/viewer/2022033023/56649cc05503460f94987833/html5/thumbnails/13.jpg)
Growth Effect
![Page 14: Spatial and temporal variability in Atka mackerel (Pleurogrammus monopterygius) female maturity at length and age. A component of NPRB project 0522: Reproductive.](https://reader030.fdocuments.net/reader030/viewer/2022033023/56649cc05503460f94987833/html5/thumbnails/14.jpg)
Length at age F
ork
leng
th (
cm)
20
25
30
35
40
1 2 3 4 5
East
West
Age (years)
![Page 15: Spatial and temporal variability in Atka mackerel (Pleurogrammus monopterygius) female maturity at length and age. A component of NPRB project 0522: Reproductive.](https://reader030.fdocuments.net/reader030/viewer/2022033023/56649cc05503460f94987833/html5/thumbnails/15.jpg)
Affect of growth on maturity at age
0
0.5
1
25 30 35 40 45
Mean Length of 4 YOIn East and West
Mean Length of 3 YOIn East and West
Fork length (cm)
Pro
port
ion
mat
ure
0.08
0.04
![Page 16: Spatial and temporal variability in Atka mackerel (Pleurogrammus monopterygius) female maturity at length and age. A component of NPRB project 0522: Reproductive.](https://reader030.fdocuments.net/reader030/viewer/2022033023/56649cc05503460f94987833/html5/thumbnails/16.jpg)
Model:Growth affect on maturity at length
• Predicted length determined separately for each area from von Bertalanffy model
• Maturity at age constant for each area
![Page 17: Spatial and temporal variability in Atka mackerel (Pleurogrammus monopterygius) female maturity at length and age. A component of NPRB project 0522: Reproductive.](https://reader030.fdocuments.net/reader030/viewer/2022033023/56649cc05503460f94987833/html5/thumbnails/17.jpg)
0
0.5
1
20 25 30 35 40 45
East
West
Model:Growth affect on maturity at length
Predicted fork length (cm)
Pro
port
ion
mat
ure
![Page 18: Spatial and temporal variability in Atka mackerel (Pleurogrammus monopterygius) female maturity at length and age. A component of NPRB project 0522: Reproductive.](https://reader030.fdocuments.net/reader030/viewer/2022033023/56649cc05503460f94987833/html5/thumbnails/18.jpg)
Year class strength effect
![Page 19: Spatial and temporal variability in Atka mackerel (Pleurogrammus monopterygius) female maturity at length and age. A component of NPRB project 0522: Reproductive.](https://reader030.fdocuments.net/reader030/viewer/2022033023/56649cc05503460f94987833/html5/thumbnails/19.jpg)
Results: Maturity at length over time (East)
0
0.5
1
25 30 35 40 45 50
Fork Length (cm)
Pro
po
rtio
n M
atu
re
1994
2002
2003
2004
![Page 20: Spatial and temporal variability in Atka mackerel (Pleurogrammus monopterygius) female maturity at length and age. A component of NPRB project 0522: Reproductive.](https://reader030.fdocuments.net/reader030/viewer/2022033023/56649cc05503460f94987833/html5/thumbnails/20.jpg)
Results: Maturity at length over time (West)
0
0.5
1
25 30 35 40 45 50
Fork Length (cm)
Pro
po
rtio
n M
atu
re
1993-1994
2002
2003
![Page 21: Spatial and temporal variability in Atka mackerel (Pleurogrammus monopterygius) female maturity at length and age. A component of NPRB project 0522: Reproductive.](https://reader030.fdocuments.net/reader030/viewer/2022033023/56649cc05503460f94987833/html5/thumbnails/21.jpg)
2002
0
10
20
30
25 30 35 40 45
Age-6+
Age-5
Age-4
Age-3
Age-2
2003
0
20
40
60
25 30 35 40 45
Age-6+
Age-5
Age-4
Age-3
Age-2
Num
ber
of F
emal
es
Fork length (cm)
![Page 22: Spatial and temporal variability in Atka mackerel (Pleurogrammus monopterygius) female maturity at length and age. A component of NPRB project 0522: Reproductive.](https://reader030.fdocuments.net/reader030/viewer/2022033023/56649cc05503460f94987833/html5/thumbnails/22.jpg)
Maturity at length by age
0
0.5
1
25 30 35 40 45 50
Fork length (cm)
Pro
port
ion
mat
ure
3 Year olds
4+ Year olds
![Page 23: Spatial and temporal variability in Atka mackerel (Pleurogrammus monopterygius) female maturity at length and age. A component of NPRB project 0522: Reproductive.](https://reader030.fdocuments.net/reader030/viewer/2022033023/56649cc05503460f94987833/html5/thumbnails/23.jpg)
Year Class Effect Model
• Constant maturity at age • Constant growth (age/length key)• Numbers at age vary according to stock
assessment estimates
![Page 24: Spatial and temporal variability in Atka mackerel (Pleurogrammus monopterygius) female maturity at length and age. A component of NPRB project 0522: Reproductive.](https://reader030.fdocuments.net/reader030/viewer/2022033023/56649cc05503460f94987833/html5/thumbnails/24.jpg)
Model resultsMaturity at length changes due to year class strength
0
0.5
1
20 25 30 35 40 45 50
Pro
port
ion
mat
ure
Fork length (cm)
![Page 25: Spatial and temporal variability in Atka mackerel (Pleurogrammus monopterygius) female maturity at length and age. A component of NPRB project 0522: Reproductive.](https://reader030.fdocuments.net/reader030/viewer/2022033023/56649cc05503460f94987833/html5/thumbnails/25.jpg)
Discussion
• Atka mackerel maturity determined more by age than length (although length has effect)
• Growth affects maturity at length (McDermott and Lowe 1997)
• Year class strength affects annual maturity at length (4 cm expected variability)
![Page 26: Spatial and temporal variability in Atka mackerel (Pleurogrammus monopterygius) female maturity at length and age. A component of NPRB project 0522: Reproductive.](https://reader030.fdocuments.net/reader030/viewer/2022033023/56649cc05503460f94987833/html5/thumbnails/26.jpg)
0
25
50
0 2 4 6
Maturation trade-off (Stearns 1992)
Age
Siz
e
X
![Page 27: Spatial and temporal variability in Atka mackerel (Pleurogrammus monopterygius) female maturity at length and age. A component of NPRB project 0522: Reproductive.](https://reader030.fdocuments.net/reader030/viewer/2022033023/56649cc05503460f94987833/html5/thumbnails/27.jpg)
0
25
50
0 2 4 6
Maturation trade-off (Stearns 1992)
Age
Siz
e
X
Constant size = mortality risk
Constant age = fecundity loss
XX
![Page 28: Spatial and temporal variability in Atka mackerel (Pleurogrammus monopterygius) female maturity at length and age. A component of NPRB project 0522: Reproductive.](https://reader030.fdocuments.net/reader030/viewer/2022033023/56649cc05503460f94987833/html5/thumbnails/28.jpg)
Closer to constant maturity at age
• Mortality risk relatively high. M~0.3.
• Lowered fecundity risk mitigated by nest guarding.
Mortality risk
Lowered fecundity risk
![Page 29: Spatial and temporal variability in Atka mackerel (Pleurogrammus monopterygius) female maturity at length and age. A component of NPRB project 0522: Reproductive.](https://reader030.fdocuments.net/reader030/viewer/2022033023/56649cc05503460f94987833/html5/thumbnails/29.jpg)
Discussion
• Atka mackerel spawning biomass estimates robust to growth changes (stock assessment uses maturity at age)
• Stock assessments should incorporate maturity at length or age based on what controls maturity for each species
• Growth changes in a trend (climate trends) would cause consistent bias
![Page 30: Spatial and temporal variability in Atka mackerel (Pleurogrammus monopterygius) female maturity at length and age. A component of NPRB project 0522: Reproductive.](https://reader030.fdocuments.net/reader030/viewer/2022033023/56649cc05503460f94987833/html5/thumbnails/30.jpg)
0
25
50
0 2 4 6
Error of using constant length for maturity when age is appropriate
Age
Siz
e
XX
X
Stock assessment assumes
Actual
Error in Length of maturity
![Page 31: Spatial and temporal variability in Atka mackerel (Pleurogrammus monopterygius) female maturity at length and age. A component of NPRB project 0522: Reproductive.](https://reader030.fdocuments.net/reader030/viewer/2022033023/56649cc05503460f94987833/html5/thumbnails/31.jpg)
0
25
50
0 2 4 6
Actual
Stock assessment assumes
X
Error of using constant age when length is appropriate
Age
Siz
e X X
Error in maturity at age
![Page 32: Spatial and temporal variability in Atka mackerel (Pleurogrammus monopterygius) female maturity at length and age. A component of NPRB project 0522: Reproductive.](https://reader030.fdocuments.net/reader030/viewer/2022033023/56649cc05503460f94987833/html5/thumbnails/32.jpg)
Acknowledgements
• Field collections by Barney Baker, Eric Dobbs, Allen Harvison, Elaine Herr, Justin Keesee, Scott McKillip, Sandi Neidetcher, James Nimz, Kimberly Rand, Ty Yasenak, Ingwar
• Kimberly Rand,Peter Munro, Liz Conners, Bing Shi, Sandra Lowe
• Cascade fishing, F/T Seafisher• NPRB (Project 0522)