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MAR 315 > Fisheries > Flashcards

Fisheries Flashcards

1
Q

Upwelling Areas

A

Rising currents in the water column bring nutrient-rich water to the surface

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2
Q

Continental Shelves

A

Relatively shallow, highly productive

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3
Q

Estuaries

A
  • Mixing of salt and fresh water
  • Streams empty into oceans
  • Important nursery areas
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4
Q

Open Ocean

A
  • Less productive
  • Fisheries target larger migratory species
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5
Q

What happened to fishing practices when class-divided urban societies emerged five thousand years ago?

A

Fish were caught for sale rather than consumption
* Serving fresh fish was seen as a status symbol for the rich*

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6
Q

What is the fish event horizon?

A

The rapid expansion of commercial fishing in the North and Baltic seas

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7
Q

What is the significance of the Industrial Revolution in regards to the rising industry?

A

Steam powered vessels replace sailboats
Fishermen can travel farther and fish in deeper waters

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8
Q

Describe the technological advancement of fishing

A

1930s: Electrically generated sound pulses are used to locate fish
1950s: Fish-finding echo sounders work vertically allowing fishermen to see fish below the vessel
- Sonar is applied to search horizontally around the boat
- Radio and satellite transmissions tell fishermen where fish are and where they are going

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9
Q

What information can fishermen receive from sonar?

A
  • Size
  • Abundance
  • Movement
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10
Q

Passive sonar

A

Listening for sounds made by a vessel

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11
Q

What event lead to the advancement of the sonar technology that is commonly utilized in marine research today?

A

WWII
Submarine warefare

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12
Q

Active sonar

A

Emitting pulses of sounds and listening for echos

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13
Q

What is the biggest technological advancement that lead to overfishing?

A

Fish echo sounders

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14
Q

How are radios and satellites utilized by fisheries?

A

They tell fishermen where the fish are and where they are going

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15
Q

What is a fishery?

A

Areas where fish are caught for commercial or recreational purposes. This can be a body of water or fishing activities.
Not just referring to fishing vessels

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16
Q

What are the three different types of fisheries?

A
  1. Commercial
  2. Recreational
  3. Subsistence
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17
Q

Subsistence Fishing

A
  • Fishing for personal, family and community consumption
  • Noncommercial
  • Traditional methods (no big fishing vessels)
  • Fish used for food, shelter, clothing etc.
  • Crucial for sustainable livelihoods
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18
Q

Recreational Fishing

A
  • Fishing for sport or pleasure
  • Integral part of American coastal life
  • important economic driver
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19
Q

Commercial Fishing

A
  • Fishing for commercial profit
  • Mostly from wild fisheries
  • Provides large quantities of food to many countries around the world
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20
Q

Longline

A
  • Trail a long line behind a boat
  • Bait hooks attached to nets at intervals in order to attract fish
  • Used for pelagic (midwater) or demersal (bottom) fishing
  • Can span up to 60 miles long
  • Can have unintended impacts on non-target fish, birds, and other life
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21
Q

Gillnets

A
  • Wall / curtain of net that hangs in the water
  • Size of fish caught depends on the size of the net meshing
  • Hard to target specific fish –> High bycatch
  • No disruption of benthic habitat
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22
Q

Purse Seine

A
  • Used for dense schools of single-species fish (ex: tuna)
  • Vertical net surrounds fish then bottom is drawn together
  • Bycatch = low
  • No contact with seabed
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23
Q

Pots and Traps

A
  • Made from wood, wire, or plastic
  • Used to catch crustaceans (ex: lobster / crab)
  • Cone shaped entrance (animals can climb in but cant escape)
  • Deployed on the seabed for ~24 hours
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24
Q

Pelagic Trawl

A
  • Cone shaped / closed at one end to trap fish
  • Pulled through mid-water NOT seabed
  • Acoustic technology (sonar / echo-finders) locates position and depth of fish
  • Methods are employed to limit bycatch
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25
Q

Dredging

A
  • Rigid structure towed along seabed
  • Bar (with / without teeth) dislodges shellfish as it drags over sediment
  • Used to catch bivalves (oysters, scallops, and clams)
  • High ecological damage
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26
Q

Bottom Trawl

A
  • Cone shaped / closed at one end to trap fish
  • Pulled just above or on seabed (does NOT dig up benthic community)
  • Efficient in capturing large numbers of fish
  • Large impacts through bycatch and seabed damage
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27
Q

What fishing gear is the most profitable?

A

Bottom Trawls
They also cause the most damage

28
Q

Bycatch

A

The accidental capture of animals during industrial fishing
Up to 17% of all commercially harvested fish

29
Q

What is the average bycatch rate for longline fishing?

A

20% of total catch

30
Q

Ghost Net

A

Fishing net that has been abandoned or lost in the ocean

31
Q

Describe ghost fishing in regards to gill net bycatch

A
  • Gill nets can be easily lost resulting in fish and other organisms getting caught in the free floating nets
  • These trapped organisms will then attract predators (self baiting) which can then get caught in the nets
32
Q

What fishing practice was introduced as a result of the North Atlantic Right Whale?

A
  • NARW deaths are caused by lines associated by lobster traps and gill nets
  • State specific colors for gear marks are introduces
  • Increase in number of areas requiring marked lines
  • Gear configurations modified to reduce the number of vertical lines
33
Q

Dolphin Safe Tuna

A
  • Tuna tracking and verification program (TTVP)
  • Created by NOAA Fisheries
  • Requires written statement from captain of fishing vessel that states that no dolphins were killed or seriously injured while fishing for tuna
  • Captains must also complete Dolphin-Safe Captains Training Course
34
Q

Trolling / Pole and Line Fishing

A
  • Pretty sustainable
  • Requires a lot of knowledge of fish behavior
  • Low to no bycatch
  • Utilized for small-scale fishing
35
Q

What is the importance of the bottom community?

A

This is where the most biodiversity occurs
5 - 8cm of sediment

36
Q

What happens when a diverse fishing community is fished with bottom trawl gear?

A
  1. Original target fish population declines
  2. Other fish species replace target fish species
  3. Visible changes in habitat structure
37
Q

What is the difference between natural disturbances and fishing disturbances?

A
  1. Natural disturbances: most species have evolved to repopulate in disturbed sites
  2. Fishing disturbances: there is shorter recovery time in between fishing disturbances leaving no time for adaptation
38
Q

Trawling can be compared to clear cutting a forest. While both are harmful to the environment, why is trawling more harmful to the environment?

A
  • More area is impacted by trawling
  • The return time of the disturbance is shorter in the ocean
  • The seafloor is publicly owned (less regulation)
  • Less legal framework is established to regulate trawling
  • Less public awareness
39
Q

Why is it hard to regulate fisheries?

A

IUU: illegal, unreported, unregulated
It is difficult to determine how much is being taken out illegally

40
Q

Describe illegal, unreported, and unregulated fishing and why it is a threat?

A

Catching fish without abiding by government and international regulations. This threatens:
- Ocean ecosystems
- Sustainable fisheries
- Economic security
- Natural resources that are critical to global food security
- Puts law abiding fishermen and seafood producers at a disadvantage

41
Q

The Law of The Sea

A

A body of customs, treaties, and international agreements by which governments maintain order, productivity, and peaceful relations on the sea

42
Q

Exclusive Economic Zone (EEZ)

A

Area in which a coastal state has sovereign rights to explore, exploit and conserve natural resources whether living or nonliving

43
Q

What causes marine fisheries to decline?

A
  • Overfishing (rate of mortality > natural rate)
  • Highly efficient technology (radar, sonar etc.)
  • Bycatch (capture of non-target species)
  • Overcapacity (fishing fleets are larger than necessary)
44
Q

What factors increase vulnerability to overexploitation?

A
  • Life history (k-selected species = more vulnerable)
  • Migratory species (predictability)
  • Schooling (easy targeted by fishing technology)
45
Q

What has happened as a result to the development and expansion of fisheries?

A
  • Decrease in size and lifespan of targeted fish (removal form the population before full size potential is reached)
  • Lower fecundity as an adaptation to make up for early removal (reproduction is occurring at earlier ages and smaller sizes)
  • Alteration of the make up of many ecosystems
  • Speeds up the rate of nutrient turnover
46
Q

What life history trait can fishing pressure and human activity influence?

A

The age at which fish reach sexual maturity

47
Q

Selective Fishing

A

Intensive fishing can selectively remove larger / older fish from a population (resulting in induced evolution)

48
Q

Induced Evolution

A

Individual fish being maturing at a smaller size

49
Q

Describe the growth rate of fish

A

Fish have the ability to grow (get bigger) throughout their entire lifespan BUT this growth is limited by factors such as food

50
Q

What is the L50 age for fish?

A
  • The size / age of the fish at maturity
  • Length at maturity can vary by species, region and sex
  • This age is sensitive to density, temperature and food resources (dynamic)
51
Q

_____ and _____ are a function of body size

A

Survival and reproduction

52
Q

Fecundity

A

Reproductive capacity of an organism

53
Q

Recruitment

A

Number of young fish that survive to enter a fishery or join a population
Measured as number of individuals reaching a certain size or age at which they become vulnerable to fishing

54
Q

Spawning Stock Biomass

A
  • Biomass of all fish beyond L50 age
  • Proxy for stock reproductive potential (SRP)
  • Used to indicate level of biomass below which productivity is affected
55
Q

What does spawning stock biomass (SSB) not account for?

A

Changes in fecundity, egg viability, sex ratio

56
Q

What is relationship between size and fecundity?

A

Larger females are more fecund

57
Q

Describe skewed sex ratios?

A

Removing individuals of one sex over the other
If a fishery targets larger / older individuals of a species it may inadvertently catch more females than males

58
Q

Simultaneous Hermaphroditism

A

One organism has both male and female sex organs and produces both gametes

59
Q

Sequential Hermaphroditism

A

An organism switches from its inborn sex to the opposite sex

60
Q

Protogyny (protogynous) hermaphroditism

A

Female to male

61
Q

Protandry (protandrous) hermaphroditism

A

Male to Female

62
Q

When is hermaphroditism advantageous?

A

When the reproductive value in one sex is greater when the organism is small and in the other sex as it grows bigger
*If females benefit more than males from being larger male to female sex change is most advantageous

63
Q

When can hermaphroditism become an issue?

A
  • The cue to switch sexes is triggered by a decline in male abundance
  • As males get caught females might undergo sex changes at smaller sizes
  • Result in fish disappearing from heavily fished areas unless recruitment comes from elsewhere
64
Q

Describe fishing down the food web

A
  • The larger easier to catch species are removed from an ecosystem first
  • When these fish are depleted, fishermen move on to the next biggest species
  • This continues down the food web
65
Q

Commercial Extinction

A

Species decline below a level that it is economically profitable (ex: Atlantic cod)

66
Q

What drives overfishing?

A
  • Rising consumption (the human population continues to grow)
  • Marine fisheries provide much needed food and employment

MAR 315 (10 decks)

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