Environmental Engineering Reference
In-Depth Information
For years, fish harvest numbers remained stable, so many people assumed that the fisheries themselves were
stable. But the fact is that population declines were simply balanced by developments in fishing techniques and
technologies, including fishing in deeper waters, setting out more nets and lines, fishing for a longer period of
time, traveling farther for the harvest, and using better technologies to locate the target. Not only does over-
harvesting affect fishery populations, but it has economic impact on the individual, local, regional, and national
scale.
Coral reefs
Very sensitive yet important aquatic ecosystems are coral reefs. Within the past half-century, though, these
areas have been dramatically harmed by human activities, including pollution, harvesting of corals, acidifica-
tion of the oceans, and water temperature changes. The changing aquatic environment around coral reefs has
lead to a process called coral bleaching, in which the microorganisms (called zooxanthalae) that live in a sym-
biotic relationship with coral leave the coral. The microorganisms provide food for the coral through photosyn-
thesis, and the coral provides shelter for them. When the zooxanthalae leave, the coral loses its source of food
and dies. It is considered "bleaching" because the microorganisms are the color in the coral, so when they
leave, the color goes as well.
Aquaculture
As an alternative to fishing, humans have developed aquaculture to raise both freshwater and marine aquatic
species in enclosed, monitored environments similar to farms on land. This helps to ensure continued and con-
sistent fish products for consumption. Whether the farm is in a large, open-water floating pen or in ponds and
tanks, there are environmental pros and cons to this newer form of agriculture. As with other human activities,
if conducted on a responsible and regulated level, aquaculture can be sustainable.
Advantages and Disadvantages of Aquaculture
Advantages
Disadvantages
Reduces bycatch
Increases risk of disease due to close proximity (monoculture)
Is energy efficient
Is associated with increased antibiotic use
Reduces consumption of wild popu-
lations
The fish may escape into the wild and could become invasive
Provides more reliable sources of
food and protein
Results in excessive waste in a small area
Some transgenic farmed fish are larger and faster than wild, so they out-
compete them for resources.
Fishing Management
Historically, fishery conservation efforts were focused on individual species like salmon or swordfish, but this
approach has proven to be largely unsuccessful. More recent management practices take an ecosystem-based
approach, creating areas in the ocean that have limited or no human activity in hopes that the species will use
these areas to restore themselves.
Fishing Laws and Treaties
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