Unit 6- Fisheries Flashcards
Driftnets
○ Span large expanses of water
Drift with currents t capture passing fish, held vertical by floats at the surface and weights at the bottom
Longline Fishing
Setting out extremely long lines with lots of baited hooked spaced along the line
Trawling Fishing
○ Dragging cone shaped nets with weights at the bottom and floats at the top through the bottom
○ Catches ground fish and benthic organisms
By-Catch:
• Accidental capture of animals (non-target organisms)
• Common in fishery practices
• Driftnetting captures dolphins, seals, sea turtles, and other fish
• Longline fishing kills turtles, sharks, and sea birds
Bottom trawling can destroy entire communities and ecosystems (can crush reefs)
Masking of Fishery Declines:
• Industrialized fishing has depleted fish stocks in various regions, but overall global catch has remained stable
• Fishing fleets have been travelling longer distances to reach less fished portions of the ocean, fishing in deeper waters
• Fishing fleets have been spending more time fishing, setting out more nets and lines
Technological advances also allow for large catches despite declining stocks
Fishing Down the Food Chain:
• As fishing increases, size and age of fish caught decline
As particular species become too rare, fisheries shift down the food chain to smaller, less valuable fish
Marine Biodiversity Loss:
• Systems with less species diversity or genetic diversity showed less primary and secondary production, less able to withstand disturbance
Reduced biodiversity reduce habitats that serve as nurseries for fish, reduce filtering and detoxification leading to algal blooms, dead zones..etc
Maximum Sustainable Yield:
• Regulation of timing of harvests, fishing techniques, scale of harvests to allow for maximal harvests of particular populations while keeping fish available for the future
• Despite efforts, fish stocks have plummeted, shift focus away from individual species and towards viewing marine resources as elements of larger ecological systems
i.e. viewing impacts of fishing practices on habitat quality, species interactions,,,,etc
Marine Protected Areas (MPAs):
Do not necessarily protect all their natural resources (allow fishing and other activities)
Marines Reserves:
• Designed to preserve entire ecosystems without human interference (no fishing)
• Can act as production factories for fish for surrounding areas (fish will disperse outside and stock nearby communities- spillover effect)
• Produce rapid and long term increases in abundance, diversity and productivity
• Decrease mortality and habitat destruction
Lessen likelihood of extirpation of species
Common Property Resources (CPR):
• Resources owned by everyone but no one in particular
i.e. everyone owns the atmosphere, but no individual owns it
2 characteristics- excludabilitly, subtractability
Excludability
§ Also referred to as “control of access”
§ Physical nature of the resource is that controlling access by potential users may be costly or impossible
i.e. emitting pollution into the air, fishing in the ocean
Subtractability
Each user is capable of subtracting from the welfare of other users
Level of exploitation by one user adversely affects the ability of another user to exploit this resource
Tragedy of the Common
• When an individual makes use of a non-private resource, they will overuse the resource because they receive all the benefits of additional use, but only a small part of the drawbacks (tragedy of the commons)
Solutions to the “Tragedy of the Commons”:
• Promoting a conscience among users (sustainability…etc)
• Government regulation
Privatization (one owner who can control access and manage the resource sustainably)
