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Fish Habitat and Otolith Chemistry. By Nate Bickford and Brenda Norcross. Otolith Introduction. The location and identification of essential fish habitat has become a major focus of fisheries management. Traditional assessments of habitat use have relied on mark and recapture techniques. - PowerPoint PPT Presentation
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Fish Habitat and Fish Habitat and Otolith ChemistryOtolith Chemistry
By By
Nate Bickford Nate Bickford
and Brenda Norcrossand Brenda Norcross
Otolith IntroductionOtolith Introduction The location and identification of essential The location and identification of essential
fish habitat has become a major focus of fish habitat has become a major focus of fisheries management.fisheries management.
Traditional assessments of habitat use Traditional assessments of habitat use have relied on mark and recapture have relied on mark and recapture techniques.techniques.
Recently fisheries managers have used Recently fisheries managers have used otolith chemistry to identify fish movement otolith chemistry to identify fish movement and habitat. and habitat.
Fish in ChukchiFish in Chukchi
Fish were collected during the Fish were collected during the Russian American Long Term Census Russian American Long Term Census of the Arctic (RUSALCA) Cruiseof the Arctic (RUSALCA) Cruise
Bering Flounder (Hippoglossoides Bering Flounder (Hippoglossoides robustus) robustus)
BF is one of the most abundant BF is one of the most abundant flatfish in the Chukchi Sea. flatfish in the Chukchi Sea.
MethodsMethods Fish were collected from 7 sites in the Chukchi Fish were collected from 7 sites in the Chukchi
Sea. Sea. Otolith were removed and thin sectioned in a Otolith were removed and thin sectioned in a
clean environment.clean environment. Chemical analyses were done by Laser Chemical analyses were done by Laser
Ablation Inductively Coupled Plasma Mass Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS; otoliths; LSX-500). Spectrometry (LA-ICP-MS; otoliths; LSX-500).
We are looking for elemental differences We are looking for elemental differences between core (natal) and edge (where they between core (natal) and edge (where they were collected).were collected).
Elemental ratio we are concerned with are Elemental ratio we are concerned with are Sr/Ca SrSr/Ca Sr8787/Sr/Sr8686, Ba/Ca, and Mg/Ca. , Ba/Ca, and Mg/Ca.
Bering Flounder were collected
at sites –
13, 15, 18, 20, 23, 25, and 58
Edge
Sr/Ca
0 2 4 6 8 10 12 14 16
Sr8
7/S
r86
0.5
0.6
0.7
0.8
0.9
1.0
1.1
1.2
1.3
Station 13Station 18Station 23Station 15Station 58Station 20Station 25
Water MassWater Mass 1 Station
13, 15, 18, & 20Water Mass 2
Station 23, 25 & 58
Water Mass 1 Station 13, 15, 18, & 20 75% 25%
Water Mass 2 Station 23, 25 & 58 28% 72%
•Using a Quadratic Discriminant Analysis (QDA) different sites were grouped as water masses
•Then I used the QDA to predict the membership in each water mass
Location/ Water Mass
Water Mass 1 Station 13, 15, 18, & 20
Water Mass 2 Station 23, 25 & 58
Station 13 62% 38%
Station 15 53% 47%
Station 18 17% 83%
Station 20 8% 92%
Station 23 0% 100%
Station 25 30% 70%
Station 58 85% 15%
Total fish 45 102
Percent of spawn in each
water mass 30% 70%
• There are multiple stocks of Bering flounder in the Chukchi Sea. •Water mass 2 is essential for Bering Flounder in the Chukchi Sea
•Why is the habitat in water mass 2 better
6
13
15
20
23
25
58
18
72º
70º
68º
66º
180º 170º 160º
WM2WM1
Preliminary data Preliminary data
Gymnocanthus tricuspisGymnocanthus tricuspis, Arctic staghorn , Arctic staghorn sculpin sculpin
Also collected during the RUSULCA cruiseAlso collected during the RUSULCA cruise
Arctic Staghorn Sculpin
were collected at sites –
6, 11,13, 15, 17,18,20, 23, 25, 27, 58 62, 73, 85, 106,
and 107
Gymnocanthus tricuspis Edge
Sr87/Ca48
0.000 0.002 0.004 0.006 0.008 0.010 0.012
Sr8
7 /Sr8
6
0.15
0.20
0.25
0.30
0.35
0.40
Station 106Station 107Station 11Station 13Station 15Station 17Station 18Station 20Station 23Station 25Station 27Station 6Station 62Station 73Station 85
Artic staghornArtic staghorn
Possible multiple groupings in three Possible multiple groupings in three to four water massesto four water masses
Next Step – discriminant statisticsNext Step – discriminant statistics
Acknowledgments
• Sonja Bickford• Robyn Hannigan• Brenda Norcross• Chris Stark• Brenda Holliday• Matt Keyse• Fisheries Otolith Group (FOG)• Tom Weingartner• Seth Danielson
• Funding
• National Science Foundation
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