Fisheries Flashcards
1
Q
Upwelling Areas
A
Rising currents in the water column bring nutrient-rich water to the surface
2
Q
Continental Shelves
A
Relatively shallow, highly productive
3
Q
Estuaries
A
- Mixing of salt and fresh water
- Streams empty into oceans
- Important nursery areas
4
Q
Open Ocean
A
- Less productive
- Fisheries target larger migratory species
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*
6
Q
What is the fish event horizon?
A
The rapid expansion of commercial fishing in the North and Baltic seas
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
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
9
Q
What information can fishermen receive from sonar?
A
- Size
- Abundance
- Movement
10
Q
Passive sonar
A
Listening for sounds made by a vessel
11
Q
What event lead to the advancement of the sonar technology that is commonly utilized in marine research today?
A
WWII
Submarine warefare
12
Q
Active sonar
A
Emitting pulses of sounds and listening for echos
13
Q
What is the biggest technological advancement that lead to overfishing?
A
Fish echo sounders
14
Q
How are radios and satellites utilized by fisheries?
A
They tell fishermen where the fish are and where they are going
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
16
Q
What are the three different types of fisheries?
A
- Commercial
- Recreational
- Subsistence
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
18
Q
Recreational Fishing
A
- Fishing for sport or pleasure
- Integral part of American coastal life
- important economic driver
19
Q
Commercial Fishing
A
- Fishing for commercial profit
- Mostly from wild fisheries
- Provides large quantities of food to many countries around the world
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
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
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
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
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
25
Dredging
- 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
26
Bottom Trawl
- 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
27
What fishing gear is the most profitable?
Bottom Trawls
*They also cause the most damage*
28
Bycatch
The accidental capture of animals during industrial fishing
*Up to 17% of all commercially harvested fish*
29
What is the average bycatch rate for longline fishing?
20% of total catch
30
Ghost Net
Fishing net that has been abandoned or lost in the ocean
31
Describe ghost fishing in regards to gill net bycatch
- 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
What fishing practice was introduced as a result of the North Atlantic Right Whale?
- 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
Dolphin Safe Tuna
- 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
Trolling / Pole and Line Fishing
- Pretty sustainable
- Requires a lot of knowledge of fish behavior
- Low to no bycatch
- Utilized for small-scale fishing
35
What is the importance of the bottom community?
This is where the most biodiversity occurs
*5 - 8cm of sediment*
36
What happens when a diverse fishing community is fished with bottom trawl gear?
1. Original target fish population declines
2. Other fish species replace target fish species
3. Visible changes in habitat structure
37
What is the difference between natural disturbances and fishing disturbances?
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
Trawling can be compared to clear cutting a forest. While both are harmful to the environment, why is trawling more harmful to the environment?
- 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
Why is it hard to regulate fisheries?
IUU: illegal, unreported, unregulated
It is difficult to determine how much is being taken out illegally
40
Describe illegal, unreported, and unregulated fishing and why it is a threat?
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
The Law of The Sea
A body of customs, treaties, and international agreements by which governments maintain order, productivity, and peaceful relations on the sea
42
Exclusive Economic Zone (EEZ)
Area in which a coastal state has sovereign rights to explore, exploit and conserve natural resources whether living or nonliving
43
What causes marine fisheries to decline?
- 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
What factors increase vulnerability to overexploitation?
- Life history (k-selected species = more vulnerable)
- Migratory species (predictability)
- Schooling (easy targeted by fishing technology)
45
What has happened as a result to the development and expansion of fisheries?
- 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
What life history trait can fishing pressure and human activity influence?
The age at which fish reach sexual maturity
47
Selective Fishing
Intensive fishing can selectively remove larger / older fish from a population (resulting in induced evolution)
48
Induced Evolution
Individual fish being maturing at a smaller size
49
Describe the growth rate of fish
Fish have the ability to grow (get bigger) throughout their entire lifespan BUT this growth is limited by factors such as food
50
What is the L50 age for fish?
- 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
_____ and _____ are a function of body size
Survival and reproduction
52
Fecundity
Reproductive capacity of an organism
53
Recruitment
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
Spawning Stock Biomass
- 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
What does spawning stock biomass (SSB) not account for?
Changes in fecundity, egg viability, sex ratio
56
What is relationship between size and fecundity?
Larger females are more fecund
57
Describe skewed sex ratios?
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
Simultaneous Hermaphroditism
One organism has both male and female sex organs and produces both gametes
59
Sequential Hermaphroditism
An organism switches from its inborn sex to the opposite sex
60
Protogyny (protogynous) hermaphroditism
Female to male
61
Protandry (protandrous) hermaphroditism
Male to Female
62
When is hermaphroditism advantageous?
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
When can hermaphroditism become an issue?
- 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
Describe fishing down the food web
- 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
Commercial Extinction
Species decline below a level that it is economically profitable (ex: Atlantic cod)
66
What drives overfishing?
- Rising consumption (the human population continues to grow)
- Marine fisheries provide much needed food and employment
