environmental effects on recruitment of northern shrimp in the gulf of maine
DESCRIPTION
Environmental Effects on Recruitment of Northern Shrimp in the Gulf of Maine. Anne Richards Michael Fogarty David Mountain NOAA National Marine Fisheries Service Woods Hole, MA. Outline. stock-recruit-environment relations mechanisms for recruit-env’t relation. - PowerPoint PPT PresentationTRANSCRIPT
Environmental Effects on Recruitment of Northern Shrimp
in the Gulf of MaineAnne Richards
Michael Fogarty
David Mountain
NOAA National Marine Fisheries Service
Woods Hole, MA
• stock-recruit-environment relations
• mechanisms for recruit-env’t relation
Outline
Northern ShrimpPandalus borealis
• Boreal distribution• Gulf of Maine=southern
limit• Locally important
fishery
from Shumway et al. 1985
Life history
Fishery
Impetus
• Conventional wisdom: temperature = primary regulating factor
• will “…not respond well to attempts to control exploitation”
(Apollonio et al. 1986)
0
2
4
6
8
10
12
14
55 57 59 61 63 65 67 69 71 73 75
Year
Lan
din
gs
(00
0 m
t)
7
8
9
10
11
12
Landings Temperature lag 4
Stock-Recruitment Series1968-2002
Northern Shrimp S-R
-2.0
-1.0
0.0
1.0
2.0
3.0
-1.5 -0.5 0.5 1.5 2.5SSB Index
Rec
ruit
Environmental Variables• Temperature anomalies (W Gulf of Maine)
– fall bottom: developmental rates, egg parasitism
– spring bottom: developmental rates, hatch timing
– spring surface: larval development
• NAO winter index
Analysis• Box-Jenkins TSA to ID factors affecting
recruitment
• S-R with environmental inputs
Results – TSASignificant crosscorrelations with recruitment
1
-4Spring Bottom TA
-1NAO
-Spring Surface TA
+2SSB
Lag Sign
without 2002
Planktonic larvae
Male maturation, gender transition
Stock-Recruitment Models
Time period Variables tested Model r2
1968-2001 SSB
Spring surface TA
Spring bottom TA
r2=0.46
1968-2002 SSB
Spring surface TA Spring bottom TA
r2=0.29
Stock-Recruit-TemperatureShrimp S-R
0
1
2
3
4
5
6
0 1 2 3 4 5 6
SSB Index
Rec
ruit
Inde
xS-R observed TA=-1.5 TA=0 TA=+1.5
Conclusion
• Shrimp recruitment dependent on SSB and spring temperatures (surface and bottom)
Mechanisms: Spring SST
• Spring surface temperature effect (larvae):– Appears intuitively correct– But counters laboratory studies: better growth
and survival at warmer temperatures.– Indirect effect, e.g. match-mismatch?
Match-Mismatch Hypothesis
• Coastal Gulf of Maine: Bloom timing determined by solar insolation (Townsend and coauthors)
• Shrimp development: temperature-dependent
Match-Mismatch Hypothesis– Bloom timing– Hatch timing – Survival rates
Bloom Timing• Townsend and Cammen
(1988): 1971-1980
• CZCS and SeaWifs
’78-’86, ’98-’03
Timing of Bloom OnsetTownsend and Cammen (1988)
30
35
40
45
50
55
71 72 73 74 75 76 77 78 79 80
Year
Julia
n D
ay
Hatch Dates
• Maine DMR fishery sampling, 1980-1983 and 1989-1993
• Probit analysis: 50% hatch, duration of hatch
Proportion Hatched1980
0.00
0.20
0.40
0.60
0.80
1.00
0 20 40 60 80 100
Julian Day
Pro
po
rtio
n H
atch
ed
Hatch Timing
Hatch Timing and Duration
10
20
30
40
50
60
70
80
90
100
80 81 82 83 89 90 91 92 93Year
Juli
an
Da
y
90% 10% 50%
Shrimp Development• temperature-dependent
Hatch Timing vs. Ocean Temperature1980-1983, 1989-1993
y = -0.038x + 169.6
R2 = 0.54
40
45
50
55
60
65
70
75
2500 2600 2700 2800 2900 3000 3100 3200
Cumulative Temperature May 1- Julian Day 40
Ju
lian
Day o
f 50%
Hatc
h
Bloom Onset and Hatch Timing
Bloom vs. Hatch Dates
30
40
50
60
70
70 72 74 76 78 80
Hatch Year
Julia
n D
ay
Bloom Hatch
Survival
Survival Ratio (R/S) vs. Mismatch
0.000.501.001.502.002.503.003.504.004.505.00
-2 3 8 13 18 23 28
Days between Bloom Onset and Hatch Timing
Su
rviv
al
Ind
ex
(R
/S)
Larval Shrimp Diet• Zooplankton bloom ~ one month later
(Townsend 1984)
March 6
no food
small diatoms
large diatoms
zooplankton
March 26
no food
small diatoms
large diatoms
zooplankton
March 13no food
small diatoms
large diatoms
zooplankton
April 1 no food
small diatoms
large diatoms
zooplankton
Stickney and Perkins (1980)
Stage I larvae
ImplicationsCumulative SST during Developmental Period
Boothbay Harbor SST
2
2.2
2.4
2.6
2.8
3
3.2
3.4
3.6
1905 1915 1925 1935 1945 1955 1965 1975 1985 1995Year
Cum
Tem
p '0
00s
Julian Day 120 - 40
Application
• Management:
Adjust fishing effort to allow higher egg deposition in warmer years
Stephen H. ClarkSummary
1) SSB and spring temperatures affect GoM shrimp rcrt
2) Spring SST effect may be mediated through match-mismatch
Ongoing Work
• Bloom timing– Solar insolation, 1982-
1999
– CZCS / SeaWiFS, ‘83-’91, ‘97-’03
• Hatch timing