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. 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. Traditional assessments of habitat use have relied on mark and recapture techniques. Recently fisheries managers have used otolith chemistry to identify fish movement and habitat. Recently fisheries managers have used otolith chemistry to identify fish movement and habitat.

Fish in Chukchi Fish were collected during the Russian American Long Term Census of the Arctic (RUSALCA) Cruise Fish were collected during the Russian American Long Term Census of the Arctic (RUSALCA) Cruise Bering Flounder (Hippoglossoides robustus) Bering Flounder (Hippoglossoides robustus) BF is one of the most abundant flatfish in the Chukchi Sea. BF is one of the most abundant flatfish in the Chukchi Sea.

Methods Fish were collected from 7 sites in the Chukchi Sea. Fish were collected from 7 sites in the Chukchi Sea. Otolith were removed and thin sectioned in a clean environment. Otolith were removed and thin sectioned in a clean environment. Chemical analyses were done by Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS; otoliths; LSX-500). Chemical analyses were done by Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS; otoliths; LSX-500). We are looking for elemental differences between core (natal) and edge (where they were collected). We are looking for elemental differences between core (natal) and edge (where they were collected). Elemental ratio we are concerned with are Sr/Ca Sr 87 /Sr 86, Ba/Ca, and Mg/Ca. Elemental ratio we are concerned with are Sr/Ca Sr 87 /Sr 86, Ba/Ca, and Mg/Ca.

Bering Flounder were collected at sites – 13, 15, 18, 20, 23, 25, and 58

Water Mass Water Mass 1 Station 13, 15, 18, & 20 Water Mass 2 Station 23, 25 & 58 Water Mass 1 Station 13, 15, 18, & 2075%25% Water Mass 2 Station 23, 25 & 5828%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 1362%38% Station 1553%47% Station 1817%83% Station 208%92% Station 230%100% Station 2530%70% Station 5885%15% Total fish45102 Percent of spawn in each water mass30%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 º 70º 68º 66º 180º170º160º WM2 WM1

Preliminary data Gymnocanthus tricuspis, Arctic staghorn sculpin Gymnocanthus tricuspis, Arctic staghorn sculpin Also collected during the RUSULCA cruise Also 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

Artic staghorn Possible multiple groupings in three to four water masses Possible multiple groupings in three to four water masses Next Step – discriminant statistics Next 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