197A - Deck 3.2 Flashcards
What is overfishing? What is its primary cause?
when too many fish are caught, so the fish can’t breed enough to recover; wasteful commercial fishing
Why is overfishing such a serious problem for the fish population?
For the human population?
1/3 of the world’s fish populations can’t breed enough to replace themselves; communities that depend on seafood have lost their source of protein
What is a bottom trawl?
What happens as it is dragged along the ocean floor?
a large, weighted net that is drug over the floor of the ocean; everything in its path is “crushed, ripped up or smothered”
How many poeople in the world depend on fish for protein?
3 billion
What are 3 examples of species that are caught by modern fishing gear as bycatch?
dolphins, sea turtles and sea birds
What are the 3 most common fishing methods resulting in bycatch?
bottom trawling, gillnets and longlines
How many small cetaceans [small whales, dolphins and porpoises] die each year from entanglement in (gill)nets?
How many sea turtles from longlines?
300,000; hundreds of thousands
What percentage of the world’s fishing haul is discarded as bycatch?
aproximately 11%, or 9 million tons
What percentage of coral colonies perish where bottom trawling occurs?
Why are coral and sponge colonies so important to other species?
as much as 90%; coral and sponge colonies provide a habitat for other sea creatures such as
Besides coral, what other sea life is unnecessarily caught by bottom trawling?
What do fishermen do with these unwanted speciments; what condition are they in?
sea mammals and turtles; throw them back into the water, dead or dying
What causes nutrient and effluent buildup on the sea floor around cages in fish farms?
What threat does this buildup cause?
Fish waste causes the build up, since fish farms are densely populated.
The buildup depletes oxygen in the water, causing “dead zones.”
Why do non-native fish that escape from aquaculture pose a threat?
[2 reasons]
1. They compete with wild species for food.
2. They may spread disease into wild fish populations.
Why is fishmeal being used to feed farmed fish such a problem for other populations?
It is often made from young wild fish. Since these fish don’t have time to breed, fishmeal puts further stress on their populations.
What are sustainable fisheries?
areas of the ocean fished at a low enough rate that fish species can sustain their population by reproducing
With rights-based management, why do fishermen stick to the strict limits?
because they always receive a preset share of the total catch
What are 3 types of fishing gear that help with bycatch?
How does each work?
1. pole and line fishing: fish caught on a pole one at at time
2. streamers; attached to longlines to scare away seabirds
3 TED (turtle exclusion devices); attached to trawlers to allow turtles to escape.
What happened when streamers became required on longlines in Alaska in 2002?
the number of albatross deaths declined by 89%
What are the 3 things that fish farmers can do to help manage pollution and disease that affects wild populations?
1. manage waste water responsibly
2. use antibiotics safely
3. locate their farms on land (ratehr than in the ocean)
What is ghost gear?
fishing equipment (such as nets) that has come loose or been abandoned in the ocean and continues to trap marine life
(To see how ghost gear can destroy marine life indefinitely, read this fascinating–and scary–article on the National Geographic website.)
What is a longline?
a type of fishing gear used in deep sea fishing; it features a long, heavy line with many baited hooks
What is a gillnet?
a long horizontal net that floats in the water; when fish swim into it, the net cords slip behind their gill cover and keep them from swimming back out
What does the term fishery refer to?
an area of the ocean where fish are caught in large numbers
