NRC260 Exam 2

Commercial Fishery
aquatic organisms = extractive resource to sell and consume
unwanted capture (dead or injured) that is discarded at sea. mostly crustaceans & detritus
Capture =?
catch + bycatch + released alive
high grading
keeping better fish
Longline fishing & bycatch
intended catch: sword fish, tuna, pacific cod
Bycatch: birds, sharks, turtles
Drift nets & bycatch
gill nets (25-50km long)
More selective but end up with ghost nets
Bottom trawling & bycatch
pulling a net across the bottom of the ocean (cod, halibut, rock fish)
Bycatch: corals, turtles, any small fish or creatures on the ocean floor)
Recreational fishery
fishing for sport or leisure w/possible secondary objective of catching for food
Impacts of rec. fishing
-direct harvest
-discards and bycatch
-abandoned gear
-habitat disturbance
minimizing impact in catch and release
minimize air exposure, handle gently, use barbless hooks
glucose level over time of air exposure = ?
linear upward trend with glucose correlating with time
Lactate level over time of air exposure = ?
slow increase to plateau
Air exposure affects
collaps and adhesion of gill filaments
persistent contaminants
-resistant to env. degradation, low water solubility, high lipid solubility
increase in conc. of contaminant within a trophic level (1st)
increase in conc. of contaminants across trophic levels (up the food chain) (2nd)


– comes from?

– dangerous because of?

-anthroprogenic conc. from waste incineration, coal burning, chlorine prod., ore extraction -bio accumulates and bio magnifies
mercury’s effect on fish
acute exposure: inc. metabolic rate
Chronic exp: impaired feeding ability (slowed down)
Dietary ingestion: severe liver damage, decreased fecundity
Acid’s effect on fish
-mobilization of Al. with decrease in PH
-Al. ^ mucus prod. (dec. gill efficiency) & dec. survival of eggs
movement impacts of culverts, dams, and water diversion
– effects diadromous fish (spawn&grow in diff. areas)
spawn in freshwater, grow in marine
spawn in marine, grow in fresh
riparian habitat
ecotone between terrestrial and aquatic zones,within flood plain
behaviors and movements of one fish species that relates to another. Ex: spawning methods, migration patterns
Invasive species
nonindigenous that have moved beyond their natural range/zone of potential dispersal
Dispersal (indigenous)
Impetus(cause): response to negative ecological interface/normal life history
Limiting factors:mobility, biological barriers, climate, food, physical barriers, predators/competitors
Dispersal (nonindigenous)
Impetus: humans (for food, sport, bio. control)
Limiting factors: bio barriers, climate, food, predators/competitors, policy, education, outreach
Perfect nonindigenous species
-High reprod., dispersal rates and genetic variability
-rapid maturity, broad native range, high tolerance of water qualities, flexible with habitats
habitat degradation causes unfavorable conditions for native species
biotic interactions in the form of predation, competition, disease/parasites
Bio and Human impacts of nonindigenous plants
Bio: shading, sequestering nutrients, o2 depletion Human: navigation, aesthetics, loss of sport fish, toxic algal blooms
examples of invasive species
grass carp, zebra mussel, lionfish, asian carp
Impact of increase in H2O temp
-increase in metabolism & energetic needs
-decrease in growth if prey prod. insufficient
-critical thermal maximum can be reached
Cascading impacts of increase in H2O temp
-change in Carbon input/nutrient loading
-change in sediment loads/mobilization of contaminants
-habitat availability, increase in invasive species, movement changes
reference point for measuring health of ecosystem