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Flashcards in 446 Aquatic Ecology Deck (279)
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211

Eastern Bering Sea sampling

cruises in sep. 2003, 2007
collected juvenile salmon, forage fish, zooplankton
186 stations
13,000 fish, 600 zooplankton samples analyzed for N, C isotopes

212

juvenile salmon studied in eastern Bering Sea

sockeye, pink, chum, coho, chinook

213

change in abundance of juvenile salmon

in cold years juvenile salmon distribution decreased in all species types
pacific cod abundance increased

214

∂13C tells

where food comes from in relation to shore
more depleted (more - ) = off-shore
less depleted (less - ) = near-shore

215

∂15N vs ∂13C

trophic enrichment of 15N up foodweb

216

algae ∂15N

4-8‰

217

∂15N, inverts.

8-14‰

218

∂15N, forage fish

10-14‰

219

predatory fish, ∂15N

10-18‰

220

why trophic enrichment of 15N?

organisms preferentially utilize the lower molecular weight isotope leading to enrichment of the heavier one

221

∂15N in plankton

must be determined for every group of plankton to set a baseline, then this baseline can be used to determine trophic level in the fish

222

juvenile salmon trophic position above zooplankton

2005 ~2
2007

223

why were juvenile salmon higher in trophic level in warm years

more food available, growing bigger/faster, consuming fish

224

why juvenile salmon lower in trophic level in cool years

less nutrients available, less food available

225

differences in N vs. S Eastern Bering Sea (EBS)

S: large shift in trophic level from warm - cold years
N: little change in trophic level

226

increasing nutrients of a system

may enhance smolt production through enhanced 1º, 2º productivity (but only up to k)

227

survival of smolts

can increase with increasing size of smolts

228

adults returns/recruits per spawner

may increase with increasing smolt size

229

high density of salmon fry

can dampen impacts of nutrients on smolt size and production by:
limiting resources available,
reducing efficiency of nutrient/energy transfer,
reducing growth/survival of fry and smolts

230

anadromous

fish, born in fresh water, spend most of life in the sea and returns to fresh water to spawn. Salmon, smelt, shad, striped bass, and sturgeon

231

management of anadromous fisheries

integrate ecological and fishery science to better understand and quantify linkages between freshwater and marine phases

232

challenges facing sustainable fisheries

-conflicting interests of stake holders and end users
-stocking/fertilization of lakes/streams beyond carrying capacity

233

to develop meaningful management models

-synthesize long-term data to determine carrying capacity and relate to spawners and production of smolts
-develop better long-term data on fry/smolt production and relation with adult return

234

upwelling systems

less than 2% of the ocean
contribute 7% to global marine PP
contribute 20% of global fish catch

235

CCS

California Current System
from the top of VI down
wind moves water south, causes upwelling, huge economic value to BC

236

Subarctic Current, Alaska Current

North of VI
boundary between varies in position, strength, and timing throughout the year and year-year

237

current system changes

affect fish catch

238

economic value of upwelling systems

ex-vessel value at least $200million
economic spin-off orders of magnitude larger
sport fishing ~$2billion
recreational, shipping value

239

ex-vessel value

post-season adjusted price/lb for first purchase of commercial harvest, usually established by determining average price for an individual species, harvested by a specific gear, in a specific area

240

Important biological processes in the CCS

basin conditions:
PDO
NPGO
ENSO
local conditions:
upwelling
Temperature
Salinity