catch more fish with science - university of southern...
TRANSCRIPT
GCRL’sCatch More Fish with Science
Spotted Seatrout
Read HendonCenter for Fisheries Research & Development&
Capt. Matt TusaShore Thing Charters
Spotted Seatrout, Cynoscion nebulosus
• a.k.a. “speckled trout”
• member of the drum family Sciaenidae
• common throughout southeastern U.S. bays and estuaries
• most popular inshore coastal species in MS
Current Fishery Information
MS Recreational Harvest Estimates
Estimated NUMBERS of Fish Harvested in Mississippi Waters, MRIP, 2014 Data
0
100,000
200,000
300,000
400,000
500,000
600,000
700,000
800,000
900,000
1,000,000
Spotted Seatrout "White Trout" "Ground Mullet" Croaker Red Drum
Est
imat
ed N
umbe
rs o
f Fis
h
Estimated POUNDS of Fish Harvested in Mississippi Waters, MRIP, 2014 Data
MS Recreational Harvest Estimates
0
100,000
200,000
300,000
400,000
500,000
600,000
700,000
Spotted Seatrout "White Trout" "Ground Mullet" Croaker Red Drum
Est
imat
ed P
ound
s of
Fis
h
Estimated Spotted Seatrout Recreational Harvest in Mississippi over Time, MRIP
MS Recreational Harvest Estimates
0
200,000
400,000
600,000
800,000
1,000,000
1,200,000
93 94 95 96 97 98 99 00 01 02 03 04 05 06 07 08 09 10 11 12 13 14
Est
imat
ed N
o. o
f Spo
tted
Sea
trout
Har
vest
ed
Estimated Total Number of Recreational Trips in Mississippi (non-specific), MRIP
MS Recreational Effort Estimates
0
500,000
1,000,000
1,500,000
2,000,000
2,500,000
93 94 95 96 97 98 99 00 01 02 03 04 05 06 07 08 09 10 11 12 13 14
Est
imat
ed N
o. o
f Ang
ler T
rips
The Science Behind the Fishery
Fishery-Independent Data (“F-I”)
F-I Annual Abundance
GCRL Fixed Stations
0
50
100
150
200
250
300
350
400
450
93 94 95 96 97 98 99 00 01 02 03 01 05 06 07 08 09 10 11 12 13 14
Annu
al A
bund
ance
Year
F-I Spatial Distribution
59177
9714653
63
58
253241
395
F-I Monthly Distribution
0
20
40
60
80
100
120
140
160
180
200
J F M A M J J A S O N D
Num
ber o
f Spo
tted
Sea
trout
Month
Temperature Influence on Abundance
0
20
40
60
80
100
120
140
46 48 50 52 54 55 57 59 61 63 64 66 68 70 72 73 75 77 79 81 82 84 86 88 90 91
Num
ber o
f Spo
tted
Sea
trout
Surface Water Temperature (F)
Salinity Influence on Abundance
0.0
1.0
2.0
3.0
4.0
5.0
6.0
7.0
8.0
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 33
Aver
age
Abun
danc
e
Surface Salinity (ppt)
Age & Growth
Determining Fish Age
© GSMFC
© GSMFC
The most abundant fish in GCRL monitoring samples are ages 1 & 2.
Length at Age - Males
0
2
4
6
8
10
12
14
16
18
20
22
24
26
28
0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0
Biological Age
TL (i
nche
s)
ObsTL PredTL
0
2
4
6
8
10
12
14
16
18
20
22
24
26
28
0 1.0 2.0 3.0 4.0 5.0 6.0
Biological Age
TL (i
nche
s)
ObsTL PredTL
Length at Age - Females
Length-Weight Relationship
0
1
2
3
4
5
6
7
8
5 10 15 20 25 30
Total Length (inches)
Tota
l Wei
ght (
lbs)
Reproduction
• Most females sexually mature by end of first year
• 65% mature at 13-in and 100% at 14-in
• Spawning season in MS = April to September
• Seagrass beds, island passes, reefs …but,little is known about local spawning habitat.
Spotted Seatrout Reproduction
• Male trout produce species-specific courtship sounds, i.e. drumming
• Acoustic receiver can detect and record the courtship sounds
FWRI
Using Courtship Sounds to Identify Spawning Habitat
Biloxi Bay
Grand Bay NERR
• Use male courtship sounds to identify spawning habitat in two Mississippi bays
Biloxi Bay–Impacted Estuary Grand Bay–Pristine Estuary
Spawning Habitat Study Objectives
• Conducted weekly passive acoustic survey
• May to September 2008-09
• 1830 - 0200 hr
• Estimated the group size and distance from hydrophone
• Size : 1-2, 3-5, small group, large group
• Distance to trout: On Top Of, Close By, In The Distance
Hydrophone Survey
356 Stations
Biloxi Bay Survey
348 Stations
Grand Bay Survey
• Most prevalent in June and July
• More prevalent in Grand Bay than Biloxi Bay
• Preferred spawning habitat for males*:
• Depth >2 meters
• Temp >80°F
• Salinity >15 ppt
Male Courtship Sounds
* for “On Top Of” or “Close By” detections
Movements & Migrations
Movements & Migrations
• angler-cooperative tagging program
• 15,206 spotted seatrout tagged
• 408 (2.7%) recaptured
• 84% of fish = 10 - 14 inches total length
Where Were Fish Tagged?
Zone I = 45% Zone II = 20%Zone III = 33% Zone IV = <1%
0 40 80 Kilometers
N
Bay St.
Louis Pass
Christia
n
Gulfport
Biloxi
Ocean
SpringsGautier
Pascagoul
a
Petit Bois I.
Horn I.Ship I.
Cat I.
Hancock County
Harrison CountyJackson County
Gulf of Mexico
Alabam
aLo
uisi
ana Zone 1
Zone 1I
Zone III
Zone 1V
ZONE IZONE II
ZONE III
ZONE IV
How Long Were Fish Out After Tagging?
0
50
100
150
200
250
300
0 4 8 12 16 20 24 28 32 36 40 44 48 52+
Num
ber o
f Spo
tted
Sea
trout
Weeks at Liberty (4-week Intervals)
How Far Did Fish Move After Tagging?
0
50
100
150
200
250
300
350
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30+
Num
ber o
f Spo
tted
Sea
trout
Miles Traveled
• 82% traveled less than 2 miles• 92% traveled less than 6 miles• distance not related to fish size
or time at liberty
Longest Distances TraveledExceptions to the Rule
35 miles in 212 days; 12.0 in
40 miles in 138 days; 12.0 in
Longest Distances TraveledExceptions to the Rule
45 miles in 200 days; 14.0 in
Longest Distances TraveledExceptions to the Rule
Feeding
Feeding
• Overstreet and Heard (1982)
• 373 spotted seatrout; 340 contained food
• Percent Occurrence = the % of stomachs in which a particular prey type occurs
Prey Type 4.0 - 11.75 12.0 - 18.5 18.75 - 24.5
Polychaetes 2.0% 9.8% 6.3%
Crustaceans 47.0% 34.4% 31.3%
Fishes 65.0% 76.3% 75.0%
Fish Size Range (Total Length, Inches)
Feeding
Bay Anchovy
Gulf Menhaden
Blue CrabBrown ShrimpClam Worm
Category Species %
Polychaete Neanthes succinea 5.6
Shrimp Farfantepenaeus aztecus 7.4
Litopenaeus setiferus 3.8
unidenfied penaeids 7.1
Palaemonetes pugio 3.5
Crab Callinectes sapidus 8.8
Fish Anchoa mitchilli 14.4
Brevoortia patronus 11.8
Membras martinica 3.8
Microponias undulatus 2.9
unidenfied fish parts 38.8
Hooking Mortality
• Do the fish that I release survive?
• 72-hour mortality study
Hooking Mortality
Hooking Mortality
0
10
20
30
40
50
60
70
80
90
Start No. 0 hours 24 hours 48 hours 72 hours
Num
ber o
f Fis
h
Live Dead n = 88
• Continue the monthly monitoring in conjunction with MDMR
• Stock assessment in progress with 2014 data being included
• Feeding analyses to begin this summer with implementation of new program
• Potential to expand acoustic network to better define habitat use
Moving Forward …
Special thanks to our primary research sponsors!
More fishing info can be found at:
http://www.usm.edu/gcrl/