Transcript AFS Tidewater Meeting talk - Quantitative Fisheries

Design and Implementation of a
Fishery-Independent Shallow Water
Trawl Survey for Maryland’s Portion
of Chesapeake Bay
Brandon Muffley and Alexei Sharov
MD Dept. of Natural Resources, Fisheries Service
Annapolis, MD
Background
• Why needed ?
– Chesapeake 2000 commitment to multispecies approaches
– Past/current studies lack spatial and temporal coverage needed
– Few studies incorporate shoal (shallow) areas
– Wide range of information gained on a variety of economically &
ecologically important species
• ChesFIMS survey
 Broad scale survey – mid-water trawls in mainstem of C. B.
 Shoal survey – bottom trawl in shallow waters of MD C. B.
Shoal Survey Design
2001
4 Strata
108 Stations
3 Sampling Periods
6 minute trawls
Surveys conducted in four
mid-Bay strata, chosen for
compatibility with broad
scale efforts, and with
existing surveys
S4
S1
Solomons
S2
Solomons
S3
• Stratified random design
• Proportional station allocation
• Trawl design from MD DNR crab survey
Shoal Survey Design (con.t)
S9
2002
9 Strata
120 Stations
3 Sampling Periods
6 minute trawls
Surveys conducted in nine
mid & upper Bay strata,
chosen for compatibility
with broad scale efforts,
and with existing surveys
S7
Annapolis
S8
S6
S5
• Stratified random design
• Proportional station allocation
based on variance estimates
Data Collection
Biological Information
• Species ID
• Length (TL)
• Weight
• Sex (blue crab)
• Gut content
Water Quality
• Temperature
• DO
• Salinity
• Depth
• Secchi
Misc. Information
• Tide State
• Bottom Substrate
• Boat Speed/RPM
• Position Coordinates
• Air Temp.
Summary Statistics
2001
May
July
September
Total
# of Trawls
103
108
107
318
# of Fish
2358
8754
4630
15742
Total Weight
(kg)
# of Species
34.8
40.2
82.1
157.1
22
22
22
36
2002
May
July
September
Total
# of Trawls
118
113
120
351
# of Fish
1837
2477
3061
7375
Total Weight
(kg)
# of Species
29.2
66.5
117.7
213.3
23
27
25
34
Species Caught
July 2002
American Eel
Atlantic Silverside
Bay Anchovy
Blackcheek Tonguefish
Blue Crab
Croaker
Harvestfish
Hogchoker
Horseshoe Crab
Lizardfish
Naked Goby
Northern Kingfish
Northern Pipefish
Northern Puffer
Northern Searobin
Oyster Toadfish
Pigfish
Silver Perch
Skilletfish
Spot
Spotted Seatrout
Striped Bass
Summer Flounder
Weakfish
White Perch
Windowpane Flounder
Winter Flounder
Yearly Distribution of Abundance
2001 2002
Total
TotalNN
0 0- 10
- 10
1111- 25
- 25
2626- 50
- 50
5151- 100
- 100
101
101- 1200
- 1200
Solomons
Solomons
NN
33
0 0 3 3 6 Miles
6 Miles
Yearly Distribution of Biomass
2002
2001
0 - 100
101 - 500
501 - 1000
1001 - 3000
3001 - 6000
6001 - 10000
10001 - 17000
Solomons
Solomons
N
5
0
Total
Totalgg
5 Miles
Overall Catch Tow -1 by Species
July 2001
September 2001
Bay Anchovy
Blue Crab
White Perch
Croaker
Spot
Striped Bass
Hogchoker
Summer Flounder
Weakfish
Lizardfish
N. Kingfish
Other
Overall Biomass Tow –1 by Species
July 2001
September 2001
Bay Anchovy
Blue Crab
White Perch
Croaker
Spot
Striped Bass
Hogchoker
Summer Flounder
Weakfish
Lizardfish
N. Kingfish
Other
Abundance Trends
Tangier Sound – Blue Crab
mean Catch tow-1
80
May
July
September
60
40
20
0
1990
1992
1994
MD DNR crab trawl survey
1996
1998
2000
2002
2004
ChesFIMS shoal survey
• Fixed stations
* Stratified random stations
• Few stations
* Numerous stations
• 16’ semiballoon otter trawl
* 16’ semiballoon otter trawl
• 6 minute tows
* 6 minute tows
5 different strata sampled by both surveys
Biological Characteristics
Bay Anchovy
450
Mean Length (mm)
400
May
Frequency
350
May
300
67.2
250
200
150
100
50
0
1520
2025
2630
3135
3640
4145
4650
5155
5660
6165
6670
7175
7680
8185
8690
9195
Length (mm)
• Size and size-at-age
• Growth rates
• Habitat Preferences/Associations
(adults & juveniles)
• Recruitment
* For a number of species
Biological Characteristics
Bay Anchovy
450
Mean Length (mm)
400
May
Frequency
350
July
300
May
67.2
July
43.9
250
200
150
100
50
0
1520
2025
2630
3135
3640
4145
4650
5155
5660
6165
6670
7175
7680
8185
8690
9195
Length (mm)
• Size and size-at-age
• Growth rates
• Habitat Preferences/Associations
(adults & juveniles)
• Recruitment
* For a number of species
Biological Characteristics
Bay Anchovy
450
Mean Length (mm)
400
Frequency
350
May
July
September
300
May
67.2
July
43.9
Sept
48.1
250
200
150
100
50
0
1520
2025
2630
3135
3640
4145
4650
5155
5660
6165
6670
7175
7680
8185
8690
9195
Length (mm)
• Size and size-at-age
• Growth rates
• Habitat Preferences/Associations
(adults & juveniles)
• Recruitment
* For a number of species
Species Diversity
By Strata
7
22
Species trawl -1
6
13
5
9
25
18
4
8
3
2
September 2002
6
11
6
11
1
0
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Species Diversity vs. Species Richness
ll
ra
e
v
O
Species Diversity
By Season
6
May
July
September
All 2001
Species trawl -1
5
22
22
4
22
3
2
1
0
Little
Choptank
Tangier
Pocomoke
Calvert
Cliffs
Overall
Species Diversity vs. Species Richness
Species Diversity
By Year
6
2001
19
2002
15
July 01 & 02
Species trawl-1
5
16
4
27
15
8
11
22
3
7
2
1
2
0
Little Choptank
Tangier
Pocomoke
Calvert Cliffs
Overall
Species Diversity vs. Species Richness
Gear Comparison Study
Why needed:
* Allow both surveys to be combined
* Estimate small scale spatial and temporal covariation
* Different sampling scheme
* Different gear – fishing efficiencies
100
mean Catch tow
-1
90
80
70
60
50
40
30
20
10
0
Deep Stations
(8m)
Shallow
Stations (4m)
Day Trawls
Night Trawls
Overall
Diet Analysis
Season
Strata
Species Collected
Spring
Summer
Fall
Total
Chester
7
14
0
21
Eastern Bay
0
2
0
2
Choptank
0
10
0
10
Little
Choptank
0
2
0
2
Tangier
28
94
48
170
Pocomoke
24
74
4
102
Patapsco
52
55
30
137
Severn/South
42
39
2
83
Calvert Cliffs
0
11
0
11
Season Total
153
301
84
538
Croaker
Spot
Weakfish
Hogchoker
Striped bass
White perch
Northern Kingfish
A. Silverside
Trophic Linkages
Predator – prey
Multispecies models
Bioenergetic models
Worm
0
0.00
0.00
0.00
0.04
Egg
Bivalve
0.46
0.00
Fish Part
Unidentified
0.00
0.00
0.00
0.00
0.00
0.00
0.04
Blue Crab
Unidentified Crab
Clupeid Egg
Unidentified
Unidentified
0.00
0.1
Razor Clam
0.2
0.08
Striped Bass - Upper Bay (n = 24)
Mussel
Barnacle
Gastropod Egg
Gastropod
Isopod
0.00
0.00
0.00
0.08
0.00
0.00
0.04
0.00
0.00
0.04
0.04
0.00
0.04
0.00
0.00
0.00
0.00
0.00
0.04
0.00
0.00
0.00
0.67
0.4
Unidentified Fish Egg
Fish
Prey Item
Skeleton Shrimp
Mysid
Cumacean
Grass Shrimp
Copepod
Copepod Egg
Amphipod
Tunicate
Diptera
Unidentified Insect
Chironomidae
0.3
Unidentified Insect Larvae
Insect Egg
Nudibranch
Unidentified
Gnathostomulid
Tube Worm
Nemertean
Flatworm
Nematode
Annelid
Polychaete
Organic Matter
Percent Weight (% W)
Sample Diets
 Gut contents flushed, sample split, taxa identified,
weighed and counted
(from Miller et. al. 2001)
Summary
Information Gained:
• Survey design and implementation
• CPUE and Biomass estimates
• Species abundance and distribution
• Life history characteristics (i.e. growth and habitat use)
• Species diversity and richness
• Recruitment
• Trophic linkages – gut analysis
• Time series of abundance
 Management Implications
Other Areas of Interest:
• Water quality
• Trawl time
• Volumetric analysis / gear comparison
Spatially
&
Temporally
extensive
Species rich
Acknowledgements
•Project funded by CBSAC through NOAA CB Office
• Nate Herman
• Tom Miller
• Jon Volstad
• Phil Jones
• Dale Weinrich
• Paul Genovese
• Harry Rickabaugh
• Keith Witeford
• Mark Matsche
• Tony Jarzynski
• Jim Mower
• Bob Sadzinski
• Marek Topolski
• Harley Speir
• Harry Hornick
• Butch Webb
• Bruce Pyle
• Jim Thompson
• Kinte Thompson
• Kevin Donaldson
• Bennie Williams
• Jen Ball
• Matapeake interns