Embed Size (px)
DESCRIPTION
Methods: Collection of Blue Catfish Otoliths. Bob Greenlee Department of Game and Inland Fisheries [email protected]. Stations in Four Tidal River Systems 2001 - 2014. Sampling Strategy. Summer Low Frequency (15 pps) Boat Electrofishing Fixed station design - PowerPoint PPT Presentation
Citation preview
Methods: Collection of Blue Catfish Otoliths
Bob GreenleeDepartment of Game and Inland Fisheries
####
#
#
### #
#
#
#####
#
#
#
###
#####
###
# #
##
#
#
#
#
##
#
# #
#
#
###
#
#
#
#
#
#
##
##
#
# #
#
##
#
#
####
#
#
##
#
#
##
#
#
##
##
#
##
#
#
#
#
#
#
##
##
#
#
#
#
#
#
##
#
##
#
#
##
#
#
#
#
#
#
#
#
#
#
##
#
###
#####
##
##
##
#
##
##
###
#
#
#
#
#
#
#
##
#
#
#
#
#
#
#
#
##
#
##
#
#
#
##
###
20 0 20 40 60 80 Kilometers
# Sampling Stations
e
Stations inFour Tidal River Systems
2001 - 2014
Sampling Strategy
• Summer Low Frequency (15 pps) Boat Electrofishing– Fixed station design– EF boat and Pick-up boat
• Standard run length• Two netters on each boat• Extra netters to assist in landing of unusually large fish (~> 20 Kg)
• Otoliths Collected for Age & Growth beginning in 2002– 2002 – 2004 otolith subsampling based on N per cm-group
• High variability in individual growth => age-length key of limited value– After 2004, stratified random subsampling
Group Freq n for group0 - 59 91.97026 618560 - max 8.02974 540
100Total N = 6725
0 - 59 CM Freq Est. n at age
Age 0 0 0Age1 0.056 347Age2 0.078 480Age3 0.073 453Age4 0.116 720Age5 0.151 933Age6 0.211 1306Age7 0.129 800Age8 0.052 320Age9 0.060 373Age10 0.047 293Age11 0.009 53Age12 0.009 53Age13 0.004 27Age14 0.000 0Age15 0.004 27Age16 0 0Age17 0 0Age18 0 0
1 6185
0 - 59 60 - TOTALAge 0 0 0Age 1 347 347Age 2 480 480Age 3 453 453Age 4 720 0 720Age 5 933 0 933Age 6 1306 0 1306Age 7 800 0 800Age 8 320 3 322Age 9 373 81 454Age 10 293 74 367Age 11 53 30 84Age 12 53 71 124Age 13 27 94 120Age 14 0 79 79Age 15 27 46 72Age 16 0 23 23Age 17 0 10 10Age 18 0 15 15Age 19 0 0Age 20 13 13Age 21 3 3
TOTAL 6725
Blue Catfish Weight (g) at Capture (Mean +/- 90% C.I.)
0
2000
4000
6000
8000
10000
12000
14000
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
Age
We
igh
t (g
)
James
Rapp
Modeling Growth – Mattaponi River
von Bertalanffy (Linf = 1,438 mm; K = 0.048; t0 = -2.305 yrs, r2 = 0.99)
L(Age) = 200.678 + (42.631 * Age)
R2 = 0.98
0
200
400
600
800
1000
1200
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
Age
Le
ng
th (
mm
)
(54)(64)
(107) (41)
(50)
N = 566(25)
(16)
(10)
(46)
(30)(14) (33)
(26)
(26)(24)
Mean Total Length-at-Age w/ 95% C.I.2006 & 2008
L(Age) = 200.678 + (42.631 * Age) r2 = 0.98
Growth Rates – Differences Among Rivers(mean total length-at-age w/ 95% Confidence Intervals)
0
200
400
600
800
1000
1200
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15Age
Mea
n T
ota
l L
eng
th (
mm
)
James
Mattaponi
Pamunkey
Rappahannock
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18
To
tal L
eng
th (
mm
)
0
200
400
600
800
1000
1200James 2002 - 2008
Age
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14
To
tal L
eng
th (
mm
)
0
200
400
600
800
1000
1200Pamunkey 2002Pamunkey 2005
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 160
200
400
600
800
1000
1200Mattaponi 02/04Mattaponi 06/08
Age
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 170
200
400
600
800
1000
1200Rappahannock 2002Rappahannock 2005
Growth – Declines in Three of Four Rivers(mean total length-at-age and 95% Confidence Intervals)
Mann-Whitney rank sum test for each age sampled
Log10 (CPUE +1)
2.6 2.8 3.0 3.2 3.4 3.6 3.8 4.0
Mea
n T
otal
Len
gth
Age
-10
(mm
)
400
600
800
1000
PamunkeyRappahannock
r2 = 0.99
r2 = 0.77
Declines in Growth Associated With Increases in Density
(Mean Total Length Age-10 and CPUE)
River A Age(Max)
Age Range in Analysis r 2
James 0.265 28.9 3–20 0.96
Mattaponi 0.208 28.5 3–13 0.78
Pamunkey 0.323 22.4 3–13 0.83
Rappahannock 0.256 29.5 2–17 0.81
Catch Curve-Based Total Annual Mortality Estimates
James 2006
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
Ln N
umbe
r
2
3
4
5
6
7
8
Rappahannock 2007
Age
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 152
3
4
5
6
7
8
Pamunkey 2006
Age
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
Ln N
umbe
r
2
3
4
5
6
7
8
Mattaponi 2006
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 152
3
4
5
6
7
8
Z = -0.319r2 = 0.77p < 0.01
Z = -0.181r2 = 0.51p < 0.01
Z = -0.171r2 = 0.39p < 0.05
Z = -0.243r2 = 0.70p < 0.01
Variable Recruitment
Year-Class
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
Res
idua
l
-2.5
0.0
2.5 James 2006James 2008
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
Res
idua
l
-2.5
0.0
2.5 Mattaponi 2006Mattaponi 2008
r = 0.94p < 0.01
r = 0.80p < 0.01
Sample From Tributary of James
Play “Shocking The James” video now
Unbelievably abundant– One of two tanks collected during 10 minutes of electrofishing on the Rappahannock River
Sample From Tributary of James
2004~ 37.6 kg
Sample From Tributary of James
Sample From Tributary of James
Sample From Tributary of James
Sample From Tributary of James
