View
212
Download
0
Category
Preview:
Citation preview
Introduction Results: Prey Quality
Acknowledgements
Results: Prey Quality • Changing seascape in the Arctic:
1.Temperature in Arctic increasing at 2X rate as rest of globe 2. Arctic susceptible to change from erosion, increased
vessel traffic and associated development, oil exploitation and potential for spills
• Changing conditions in Arctic may effect fish communities and fish health
• How is the Arctic food web currently structured and how might it change in the future?
Methods
Many thanks to the multitude of people that saved and preserved samples, including Mark Barton and ANCEP student Sam Craig, Darcie Neff and Sandy Parker-Stetter, Captain Mike Fleming of the R/V Ukpik, Hugh Oleman, Libby Logerwell and Lyle Britt and the rest of the scientific and vessel crews of the F/V Alaska Knight, the scientific and vessel crew aboard the Bristol Explorer, Alex Andrews, and Kris Cieciel, Arctic Eis program leader Franz Meuter, and . Thanks also to the folks in the bio- and chemistry labs, Robert Bradshaw, Hannah Findlay, Kevin Heffern and Tayler Jarvis. We sincerely appreciate logistical support provided by the North Slope Borough, with special recognition to Billy Adams, Robert Suydam, Craig George and Todd Sformo.
• Fish samples collected from several Arctic studies during ice-free summer months (July-September): 1.ACES - Arctic Coastal Ecosystem Survey (2012-2014) 2.SHELFZ - Shelf Habitat and EcoLogy of Fish and
Zooplankton (2013) 3.Arctic Eis (2012-2013)
• Chemical analysis of whole-body fish 1. Caloric content (bomb calorimetry) 2 Proximate composition (lipid, protein, moisture, ash) 3. RNA/DNA (relative growth index)
Energetics of Arctic Fish JJ Vollenweider1, Ron Heintz1, Leandra DeSousa2,
Kevin Boswell3, Matt Callahan1, Ann Robertson1, John Moran1
1Alaska Fisheries Science Center, NMFS, Juneau, AK 2North Slope Borough, Barrow, AK
3Florida International University, Miami, FL
The recommendations and general content presented do not necessarily represent the views or official position of the United States Government or its agencies.
Objectives Describe energetics of nearshore Arctic fish in terms of:
1. prey quality for marine mammal and seabird predators and subsistence consumers
2. body condition for survival and recruitment
Ongoing Work • Relate variation in fish condition parameters to
environmental variables (temperature, wind, prey) • Examine seasonal effects on fish condition using
opportunistic sampling during seasons with ice-cover
Beach seining Small-vessel trawling
Offshore bottom and mid-water trawling
Offshore mid-water trawling
*
Long
head
_dab
Sculp
in,fou
rhorn
Cana
dian_
eelpo
ut
Slend
er_ee
lblen
ny
Wattled
_eelp
out
Saffr
on_c
od
Sculp
in,Ar
ctic_
stagh
orn
Marble
d_ee
lpout
Wal l
eye_
pollo
ck
Pacif
ic_sa
nd_la
nce
Arcti
c_co
d
Cape
lin
Pacif
ic_he
rring
35
30
25
20
15Ener
gy D
ensi
ty (
kJ/g
dry
mas
s)
Energy Density of Arctic Fish
Gram for gram, First prize goes to herring, the best prey item! Tied for second prize are capelin, Arctic cod, Pacific sand lance & Arctic staghorn sculpin.
Which Arctic species are the top contenders as prey?
All fish together: All sizes All ages
All depths All locations
BUT, Quality of predators’ diet depends upon… 1. Size of Fish
Total energy increases exponentially with fish size.
1751501251007550
200
150
100
50
0
Fork Length (mm)
Tota
l E (
kJ)
Young-of-the-year
Mature
Photo: Craig George
R2=0.91
Surface/Midwater Trawls
R2=0.96
Photo: Darcie Neff
2. Location
Corrected for fish size: plot of regression residuals of log(Total Energy) vs. Length
On bottom, cod higher in energy along edge of Barrow Canyon.
#1
#2
Implications • Changes in prey availability may have caloric implications for
predators. • Great spatial variation in fish condition, suggesting habitat
quality of different water masses may contribute to survival/recruitment disproportionately.
• Preliminary analyses suggest wind and water temperature are important factors in fish condition
Capelin
Arctic cod
Arctic staghorn sculpin Pacific sand lance
Pacific herring Results: Condition for Survival
No affect of size on growth rate, R2=.06
R2=0.90
3. Season
Fish assimilate energy rapidly from intense foraging over the brief Arctic “summer”.
Bottom Trawls Energy Residuals of Arctic Cod
Capelin RNA/DNA
Lowest growth nearshore in warmer water and in northern Bering Sea.
Recommended