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HostHost--Size Selection and Lethality of Size Selection and Lethality of Sea Lamprey on Lake SturgeonSea Lamprey on Lake Sturgeon
Holly K. Patrick & Trent M. SuttonPurdue University, West Lafayette, Indiana
William D. SwinkHammond Bay Biological Station, Millersburg, Michigan
Introduction – Sea Lamprey Parasitism
Introduced through shipping canal (1830s)P ll G L kPrey on all G. Lakes spp.Feed on body fluids
USFWS
Kill 18 kg of fish in 12-20 months1 in 7 fish survive
US S
Introduction – Lake Sturgeon
Conservative life historyI il d 1% f hi t i l b dImperiled: 1% of historical abundance
Over-ExploitationH bit t Alt tiHabitat Alterations Deterioration of Habitat Quality
C CCape Croker
Introduction – Lampricides
Definition: A chemical which selectively kills larval seaDefinition: A chemical which selectively kills larval sea lampreys in rivers before their recruitment as parasitic adults
Routine use since 1960s3-trifluoromethyl-4-nitrophenol (TFM)5 2’-dichloro-4’-nitro-salicylanilide5,2 dichloro 4 nitro salicylanilide(niclosamide)
Introduction – Sensitivity to Lampricides
Applied in prime nursery areaApplied in prime nursery area for juvenile LKSLKS i i TFM h RWTLKS more sensitive to TFM than RWT, NOP,MSKSwim-up larvae & age-0 juvenile lake sturgeon (<100 mm length) experience 50%
t lit t l th LC f SELmortality at or less than LC50 for SEL (Boogard et al. 2003)
Introduction – No-Observable-Effect Protocol
Non-target mortality will occur for lake sturgeon <100 mm Takes ~90 days to reach 100mm (approx. August 01)
1.0x MLC for TFM 1.2x for TFM/2% niclosamide
Introduction – Trade-Off
Effects on long-term population viability?:g p p y
Parasitism Vs Lampricide-Induced Mortalityp y
[treatment] = abundance of parasitic-phase SEL = mortality
Is no observable-effect treatment protocol appropriate?
Objectives
1 Compare survival of lake sturgeon following1. Compare survival of lake sturgeon following a single sea lamprey attack among four size classes
2 Examine the effects of a single sea lamprey2. Examine the effects of a single sea lamprey attack on lake sturgeon blood chemistry
Methods - Study Design2,177-L grow-out tank
9,028-L grow-out tank
experimental tank
Methods - Size Classes
I: 470 - 570 mm FL (n = 25)II: 570 - 650 mm FL (n = 25)II: 570 650 mm FL (n 25)III: 650 - 760 mm FL (n = 15)
IV: 950 1 550 mm FL (n = 15)IV: 950 - 1,550 mm FL (n = 15)Control: 5 fish from each size class (20 fish)
Methods - Trials
PIT tag1 SEL : 1 LKSObservations: 0700, 1200, 1700 Trial end = mortality or detachmentyLength & weightBlood samplepShort- & long-term recovery
Methods – Blood Sample Analyses
2-ml arteriovenous blood sample2 ml arteriovenous blood sample4 samples per sturgeon:1 before trial1. before trial2. after trial3. end of short-term recovery
d f l t4. end of long-term recovery
Hemoglobin: Tallquist scaleH t it i h t it dHematocrit: micro-hematocrit readerPlasma protein: refractometer
Locations of Sea Lamprey Attachment
38%(15 fish)
31%(12 fish)
13%(5 fish)
Classification of Mortality
1. Direct: wound visibly penetrates the skin & fungal infection NOT present; ORAbrasions present with no visible break in the skin butAbrasions present with no visible break in the skin, but attack was >100 hr, SEL gained 10+ g in WW, & remains attached at time of mortality
I di t2. Indirect: Skin-penetrating wound & fungal infection present
Lake Sturgeon Survival
Size Class Attachments Mean Duration Mortalities(days)
I 14 1.8 1(470 – 570 mm FL) (range: 0.6 - 5.8) (direct)
II(570 650 mm FL)
13 3(range: 0 2 8 2)
4(direct)(570 – 650 mm FL) (range: 0.2 – 8.2) (direct)
III(650 – 760 mm FL)
7 3.2(range: 0.6 – 11.8)
1(indirect)(650 760 mm FL) (range: 0.6 11.8) (indirect)
IV(950 – 1,550 mm FL)
6 2.6(range: 0.4 – 4.4)
1(indirect)
Lake Sturgeon Survival – Secondary Infection
Indirect mortalities (not caused by acute-anemia)( y )Presence of mycosis: Saprolegnia spp.
Opportunistic; proliferativeAssociated with immunosuppressionppOutbreaks common following acute stress eventsSuperficial damage to skin or gills can be fatal
End of Trial: Oct 27/06 M t lit N 24/06End of Trial: Oct. 27/06 Mortality: Nov. 24/06
Percent Hemoglobin Pre-trial
Post-trial
120 120
P = 0.004 P = 0.004
20
40
60
80
100
20
40
60
80
100
01 2 3 4 5 6 7 8 9 10 11 12 13 14
Size Class I
01 2 3 4 5 6 7 8 9 10 11 12 13
Size Class II
60
80
100
120
60
80
100
120P = 0.283 P = 0.203
0
20
40
1 2 3 4 5 6 7
Size Class III
0
20
40
1 2 3 4 5 6
Size Class IVSize Class III Size Class IV
Percent Hematocrit Pre-trial
Post-trial
303540
25
30
35P = 0.017 P = 0.002
05
10152025
0
5
10
15
20
1 2 3 4 5 6 7 8 9 10 11 12 13 14
Size Class I1 2 3 4 5 6 7 8 9 10 11 12 13
Size Class II
P = 0.044 P = 0.512
152025303540
15
20
25
30
35P 0.044 P 0.512
05
1015
1 2 3 4 5 6 7
Size Class III
0
5
10
1 2 3 4 5 6
Size Class IVSize Class III Size Class IV
Plasma Protein Pre-trialPost-trial
4.55
4 55
P = 0.007 P = 0.007
11.5
22.5
33.5
44.5
11.5
22.5
33.5
44.5
00.5
1 2 3 4 5 6 7 8 9 10 11 12 13 14
Size Class I
00.5
1 2 3 4 5 6 7 8 9 10 11 12 13
Size Class II
P 0 013 P 0 274
2.53
3.54
4.55
3
4
5
6
7P = 0.013 P = 0.274
00.5
11.5
2
1 2 3 4 5 6 7
Size Class III
0
1
2
3
1 2 3 4 5 6
Size Class IVSize Class III Size Class IV
Mean % Change in Blood Chemistry
05 Size Class IIISize Class IISize Class I Size Class IV
-15-10-50
-30-25-2015
-45-40-35
Hemoglobin Hematocrit Plasma Protein
P = 0.062
F it 2 866
P = 0.070
F it 2 866
P = 0.555
F it 2 866Fcrit. = 2.866 Fcrit. = 2.866 Fcrit. = 2.866
Necropsy
Spleen: dark; black spots; enlargedLiver: blanched; enlargede b a c ed; e a gedDigestive tract: blanchedSwim bladder: congested; hemorrhagingSwim bladder: congested; hemorrhagingSaprolegniosis – wet mount of skin or gills shows broad (7 30µm) non septate hyphaeshows broad (7-30µm) non-septate hyphae
Conclusions
Mortality: 71% (of total) direct; 29% (of total) indirectSignificant differences exist before & after a sea lamprey attack for size classes:
Hemoglobin: I, IIHematocrit: I, II, IIIPlasma Protein: I, II, IIINo significant differences among size classes
Sea lamprey parasitism negatively impacts survivalSea lamprey parasitism negatively impacts survival of lake sturgeon
Additional Information
Lake sturgeon growth assessmentPlasma analyte analyses & histologyPlasma analyte analyses & histologySea lamprey mark classification key & field guideguide
Acknowledgments
The Great Lakes Fishery CommissionMichigan DNR; Wisconsin DNR; USFWSPurdy’s Fisheryy yM. EbenerM. Sepulveda, R. RodeFellow graduate students & technicians
