1How is fishery defined?
Fishery refers to the organized harvest of aquatic species, often distinguished by location/harvest method
2What can fisheries include other than just species of fish?
Any aquatic organism
3What characteristics are shared by a “fish” stock?
Single species found in a limited geographical area or specific management area
4Be able to explain the term sustainable yield
Take of a resource that doesn’t exceed its capacity to replace itself
5Be able to explain the term zone of optimal effort
Similar to maximum sustainable yield FLAG
6Be able to explain the term under-utilization
taking less than the maximum sustainable yield
7Be able to explain the term over-fishing/over-harvest
harvest that exceeds maximum sustainable yield
8How do exponential- and logistic-growth models relate to determining the maximum sustainable yield of a fishery stock?
MSY is when the harvest is right where exponential growth begins to switch to logistic growth or "flatten out"
9Be able to explain the phenomenon of sequential depletion as it relates to overharvesting.
Harvesting new species as we run out of one, obscuring the loss of resources
10Be able to explain the phrase “fishing down the food web” as it relates to sequential depletion.
If all the larger fish at higher trophic levels have been caught, more small fish will be caught because there’s more of them (less predators controlling pop) and they’re more available.
11What is a potential explanation for fishing at lower trophic levels that does not require depletion of species at higher levels?
Possible change in cultural dietary preferences
12classic example of the crash of a top predator and fishery due to overharvesting.
Collapse of Atlantic cod stocks due to overfishing led to a switch to lower trophic levels.
13Why is it important to consider catch per unit effort rather than just total catch when evaluating the stability of a fish stock?
Increased effort can keep total catch high, even when stocks are depleted. Catch per unit of effort is a better measurement because it doesn’t change/compensate.
14What do fishery managers mean by the term overcapacity as it relates to increasing technological efficiency?
When fishing vessels get more technologically advanced, they can keep catching the same number of fish despite lower stocks, obscuring trends.
15What do fishery managers mean by the term by-catch?
Inadvertently killing marine animals that weren’t supposed to be caught.
16What are some types of animals that often suffer as by-catch?
Sea turtles, dolphins
17What are three types of nets that are especially prone to by-catch?
Gillnets, trawls, longlines
18What are two examples (mentioned in lecture and the textbook) of modifications or technologies that can be employed to reduce by-catch?
Excluder devices, circle hooks
19What does the practice of aquaculture entail?
Aquaculture is the breeding, rearing, and harvesting of marine organisms in all types of water environments.
20Roughly what proportion of fish and shellfish consumed by humans comes from aquaculture?
Roughly half
21Be able to provide or recognize several negative environmental side effects that result from typical aquaculture operations.
Reduction in predators, introduction of invasives, drug pollution, fish meal and fish oil pollution, herbicide pollution, incubation of local diseases, introduction of new diseases, genetically modified fish outcompeting local fish, fish sewage
22Be able to explain the “tragedy of the commons” and how it relates to how humans have long treated the oceans.
Essentially the idea that freedom for the commons brings ruin to all
23Be familiar with the name of the ecologist whose essay in 1968 popularized the metaphor of tragedy of the commons in conservation biology.
(Garrett Hardin)
24What is an exclusive economic zone (EEZ)?
Area where a nation has property rights
25How far do EEZ’s extend from the coastlines?
200 nautical miles
26Under what organization and act were EEZ’s established?
UN convention on the law of the sea (UNCLOS) 1994
27Roughly what percentage of the ocean is covered by EEZ’s?
42%
28What is the ocean health index (OHI)?
a standardized, comprehensive attempt to quantify the status of the EEZ of each nation
29What sorts of factors are considered in calculating the OHI?
FLAG AND ASK
30What is a stock assessment model (SAM)?
They use all available data to predict whether a fish population is (or will) be declining
31For what sorts of fish and situations have SAM’s been employed?
SAMs have only been employed for a select minority of stocks by upper-income nations
32What percentage of the Earth is covered by water?
~71%
33What percentage of the water on Earth is “fresh” water?
~2.5%
34What proportion of the freshwater on Earth is frozen in glaciers and polar ice caps?
2/3
35What proportion of the freshwater on Earth is held in aquifers as groundwater?
~30%
36Roughly what proportion of the freshwater on Earth is found as liquid on the Earth’s surface (in ponds, lakes, rivers, etc.?
~0.4%
37What is a logical reason to explain why species that depend on freshwater habitats are among the most threatened with extinction?
Runoff
38Roughly what proportion of amphibian species are vulnerable, endangered, or critically endangered?
~41%
39Be able to provide or recognize reasons why amphibians are particularly sensitive to pollution and environmental degradation.
Climate change evaps wetlands, wildlife trade, habitat fragmentation, diseases, invasives introduced, pollution
40What are the three major categories of threats to the quantity/quality of freshwater habitats identified by the textbook (and specified in lecture)?
Overuse, pollution, and disruption
41What is meant by the water scarcity index? (What is a percentage of?)
Percentage of circulating renewable freshwater withdrawn for human use.
42In order, what are the three largest categories of freshwater use (by humans) globally?
Irrigation, industry, domestic
43Roughly what proportion of the water taken from rivers for agricultural irrigation is actually successfully delivered to crops and used by the plants?
~<20%
44Explain why using groundwater for large-scale crop irrigation is not sustainable. (I.e., why is groundwater a non-renewable resource for large-scale use?)
It takes centuries to recharge
45What does it mean for a river to become “de-watered”?
Basically dried up
46What’s an example of dewatering in the U.S?
The Colorado River
47What is the purpose of a levee?
prevent flooding of rivers onto natural floodplains
48Why are floodplains important habitats?
They store water and provide important habitat for fish and birds
49What are four main reasons that people dam rivers?
flood control, water reservoirs, hydroelectric power, and recreational opportunities
50Be able to provide and/or recognize several negative side effects of dams (on the natural environment as well as human livelihoods).
Flooded habitats/communities, greenhouse gas emissions from flooded vegetation, loss of downstream aquifers, river bank erosion, salinity/waterlogging, loss of livelihood from fisheries, trans-boundary water competition, limited migration of aquatic organisms, decreased sediment transport downstream, resovoir induced seismicity
51What is meant by the phenomenon called reservoir-induced seismicity?
Dam-caused earthquakes
52What is the average lifetime of a typical earthen dam?
~50 years
53What are some examples of reasons that dams (even concrete ones) have limited lifetimes?
Cracking, slide, seepage, livestock damage, wave erosion, rodent activity, leakage out of conduit, internal erosion
54What are the main causes of sedimentation of streams and rivers?
construction, agriculture, deforestation, etc
55What are some of the main ways that sedimentation negatively affects organisms living in streams and other freshwater habitats?
decreases clarity, clogs gills, buries vegetation, destroys breeding grounds, etc.
56Be able to explain how and why excess nutrients can cause pollution and environmental harm in freshwater ecosystems.
can cause algal blooms and eutrophication in freshwater ecosystems
57Which element is a particular cause of eutrophication in freshwater habitats?
Phosphorus
58Be able to provide and/or explain several of the main negative effects that eutrophication has on aquatic ecosystems.
Toxic algae blooms, bacterial decomposition of dead algae depletes water of O2, sunlight cant penetrate leading to dead vegetation, hypoxia leads to dead zones extending from coastal areas.
59Be able to explain why freshwater habitats are so susceptible to pollution by toxic chemicals. (Think in terms of the wide variety of sources of pollutants that are created in a typical watershed.)
Runoff from sewage, farms, industry, landfills, residential buildings, oil spills, etc.