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ENVS 195 EXAM > Oceans & Fisheries > Flashcards

Oceans & Fisheries Flashcards

1
Q

Why are oceans important?

A
  • integral for sustaining life (80% of all life is in oceans & phytoplankton provide large portion of oxygen)
  • a key component in global cycles and energy flows
  • our lack of understanding hinders sustainable use
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2
Q

What are the 5 major ocean challenges?

A
  1. fisheries
  2. pollution
  3. energy
  4. coastal development
  5. climate change
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3
Q

Describe benefits of fisheries

A
  • most fishing occurs on continental shelves (within 200 nautical miles of shore) making it a very important social, cultural and economic activity
  • fishing provides 20% of the world’s animal protein
  • many communities dependent on fishing as a livelihood
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4
Q

What is the challenge with fisheries?

A
  • 80% of fisheries overexploited or crashed
  • the size of species is declining and there is increased mortality b/c fish reproducing at a young age (evolution: greater numbers of fish at a smaller size to meet demand)
  • shifting baseline
  • prey switching & serial depletion
  • by-catch & bottom trawling
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5
Q

What is a shifting baseline?

A

When there is no historical information, the current/recent info is used as a baseline for TAC/sustainability, but if there has already been a decline, the baseline will be biased and inaccurate

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6
Q

What is prey switching?

A

It occurs when a preferable species is unavailable so predators & fishermen switch to the next preferable species and so on. This often results in serial depletion & fishing down the food chain.

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7
Q

What is serial depletion?

A

It is caused by prey switching and is when fishermen’s stock levels stay the same, but many specific species stocks have been depleted.

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8
Q

What is by catch?

A

It is any species that is not the target species caught during fishing & usually ends up going to waste (ex. sharks and dolphins caught in tuna fishing). Bottom trawling often highly contributes to this

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9
Q

Why is bottom trawling a problem?

A

It causes major habitat destruction due to heavy nets dragged along the sea floor and often results in a lot of bycatch

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10
Q

What is the challenge with pollution?

A
  • oceans are the ultimate pollution sink b/c all water ends up in the oceans & many sources bring many pollutants to the ocean (ex. plastics, oils, stormwater, etc.)
  • there are many toxic chemicals and oxygen depletion often occurs that both reduce species populations and limit reproductive abilities
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11
Q

What is the problem with toxic chemicals?

A
  • they are endocrine disruptors (disrupt the natural hormone processes in species)
  • they are found in many soaps, shampoos, cosmetics, cleaners, etc. that get washed into the ocean
  • causes hermaphrodization and feminization
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12
Q

What is hermaphrodization and feminization?

A

Hermaphrodization: the growth of male and female reproductive organs, limiting reproductive success
Feminization: greater number of females born

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13
Q

What is the problem with oxygen depletion?

A
  • nutrient enrichment leads to algal blooms that take a lot of oxygen away from other bottom plants & when those plants die, oxygen is required for decomposition which means even less is available for underwater species
  • leads to low oxygen (hypoxia) or no oxygen (anoxia) which could cause possible dead zones
  • increase in masculinization (more males are born)
  • jellyfish populations increasing (unsustainable for other species b/c they hold a lot of oxygen)
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14
Q

What is the challenge with energy?

A
  • there is a high world energy demand & fossil fuels are the main source
  • oil/gas reserves are high risk with low accessibility (ex. 60% oil from marine sedimentary rock)
  • three potential pollution sources:
    1. oil rig spills
    2. chronic drilling (seepage into water)
    3. transportation accidents
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15
Q

What happened with the Exxon-Valdez Oil Spill 1989?

A
  • 11 million gallons of oil spilled on Alaskan coast
  • ocean currents spread around 600 miles
  • 500 000 birds killed
  • long term impacts on reproductive systems (fish spawning grounds covered in oil prevented reproduction)
  • extensive clean up & annual clean up (very small amount of oil removed as it’s still an issue today)
  • many species still not recovering (ex. Pacific herring - keystone species)
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16
Q

What is the challenge with coastal development?

A
  • 21/33 megacities are coastal
  • lacking/fragmented environmental management (lack of sewage treatment, different policies globally, etc.)
  • half of all countries have no coastal legislation
  • highly degraded coastal lands from cities
17
Q

What is the challenge with climate change?

A
  • warming sea surface temperatures contribute to destroyed coral reefs & hold less carbon (potentially turn from a carbon sink to an emitter)
  • impacts circulation patterns (weather, fisheries, etc.)
  • Arctic regions impacted (sea ice loss/break up, etc.)
18
Q

Describe the east coast fisheries

A
  • it was believed that we could not deplete fish sources & fishing very important economically and culturally to Atlantic Canada
  • 1977: Canada declares offshore economic zone (1/3 outside Canadian jurisdiction)
  • 1989: TAC significantly reduced
  • 1992 cod moratorium: fisheries collapsed causing high unemployment levels
19
Q

What factors caused the cod fisheries collapse?

A
  • foreign overfishing b/c quotas were higher & minimal monitoring so harvest numbers forged
  • domestic overfishing due to industrial offshore fishing (bottom trawling & excess yields)
  • biased and unreliable science & management b/c unknown facts and assumptions
  • inappropriate incentives for plants & workers (dependency on EI, people pushed into resource extraction)
  • environmental conditions (colder waters)
  • predators (believed closure of seal hunt responsible for depletion)
20
Q

What factors were blamed and what factors were actually the cause of the cod fisheries collapse?

A

Environmental factors blamed, but overfishing actual cause.

21
Q

How are the cod recovering?

A
  • believed fisheries would be closed short term but still closed today b/c there was a 97% pop decline in 30 year period
  • finally beginning to see evidence of recovery (pop and size increasing as other fish pops crashed - opportunity)
  • encouraged resource management practices
22
Q

What should fisheries managements include?

A
  • scientific understanding
  • traditional local ecological knowledge
  • understanding of history and other factors
23
Q

Why are coral reefs important?

A

They are oceanic rainforests that are diverse and productive. Most are found near the equator as they use solar energy. They have symbiotic relationships with zooxanthellae that live in the coral & provide food source in return. They provide ecosystem services like organic waste treatment & food production.

24
Q

How does coral bleaching occur?

A

If the water is too warm, zooxanthellae leave and coral dies. Overfishing of sharks also affects reef health.

25
Q

Why are coral reefs so highly threatened?

A
  • they are highly threatened due to coastal erosion, fishing, pollution, etc., leaving coral reefs rapidly disappearing
  • excess CO2 leads to reef extinction b/c CO2 absorbed by oceans to make carbonic acid, but if the pH is too low, then reefs cannot grow
26
Q

Why could fishing down the food chain be beneficial?

A

It provides food for more people while protecting top predators

27
Q

What is the issue with longline/gill net fishing?

A

It kills many sea turtles, birds and sharks annually

ENVS 195 EXAM (10 decks)

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