Human effect on the ocean Flashcards
what are marine recources used for?
food
products
materials
recreation
what type of organisms a re harvested from the ocean
finfish (about 90% of worldwide harvest)
shellfish
jellyfish, sea cucumbers, polychaetes and seaweed
how much of the animal protein consumption annually is attributed to seafood?
30%
growth of fisheries industry from 1950’s to present
5 x
worldwide catches still constant
major fishing areas location
near coast over continential shelf
what kind of fish are easiest to catch
demersal species
high _______________ in these areas means more species are present
primary production
what are clupeoid fishes?
Small. plankton-feeding fishes that form huge schools: anchovies, sardines, menhaden, shad, and herrings
caught with purse seines
how are clupeoid fishes used?
eaten directly
fish flour
fish meal
fish oil
what are demersal fish?
cod, haddock, hakes, pollock, whiting
info on the cod fishery of the grand banks
- peaked in the 1960’s then began to decline
- moratorium declared in 1992 to attempt to save the fishery
- closure caused high unemployment
cod is still endangered
Jacks, Mullets, Rockfishes, and Mackerals
- Important in worldwide tonnage
- cheap protein in some parts of the world
In the US, flounders and other _______ are important
flatfish
tuna are
- caught in open water
- highly priced
- caught on long lines or in gillnets
Molluscs are
- squids, cuttlefigh, and octopus important in the far east
- clams, oysters, mussels, scallops and abalones are important worldwide
second most valuable catch after finfish
Crustaceans
- prized worldwide
- command high prices
- shrimp, lobster, crab
are sea life fisheries renewable recources
yes
what is a sustanable yield
the amount that can be caught and just maintain a constant population size
what is the maximum sustainable yield?
the highest catch that can be maintained year after year without affecting the stock
if catches fall despite increased fishing effort, _____________ has occurred.
overfishing
how does habitat destruction affect the productivity of fisheries?
75% of commercially important species use estuarine areas as nursery areas
trawl use is detrimental to demersal species
when is a fishery regarded as ‘collapsed’?
when the numbers fall ot 10% of historic highs
one third are already collapsed
all will be collapsed by 2050 without action taken
why can managing these recourses be difficult?
- maximum sustainable yield is difficult to calculate
- harvested species may compete with other species and fishing pressure may affect competitive balance
-real fisheries are more complex than models - high seas are “common property”
list nine ways to manage a fishery
limit total catch
limiting length of fishing season
limiting areas open for fishing
limiting numbers of boats permitted to fish
limit gear size/type
limit size of fish caught
limit catches per boat
limit fishing methods
what is the 1996 Sustainable fisheries act?
required federal fisheries managers to develop plans to avoid overfishing, restore depleted stocks, and reduce by-catch
US fishermen and foreign fishermen with valid permits must abide by rules
what is aquiculture
aquatic organisms farming
farmed fish account for ____% of shrimp consumed annually
25%
problems with aquiculture
disease and parasites
different food requirements at different stages
cannot raise open water species difficult to maintain water quality
escaped farm species can breed with wild stocks and dilute genome
pollution
sometimes estuarine communities are destroyed to make these
other items harvested for reasons other than consumption
mangroves - for timber and charcoal
pearls, shells, and sea turtle shells for jewlery
marine recources caught by recreatuinal anglers is about ___% of the amount caught by commercial fishermen
30%
Non living recources from the ocean
NaCl
oil and gas
sand and gravel for the coal industry
freshwater via de-salination
tidal energy
polyatomic nodules- contain manganese, nickel, copper and cobalt
prehistoric evidence of aquatic recourse use
150,000 years ago
fishhooks, seashell artifacts, mounds of empty mollusc shells
__________ constitute 85% of the total world marine catch
finfish
___% of the worlds major fisheries are located on coastal waters and over half of the catches are taken from less than __% of the ocean surface
95%, 70%
where are most of the exhausted fisheries?
Atlantic, Pacific, Mediterranean
what did cod begin to do as a response to poulation decline?
maturing at a younger age
Practically all salmon consumed now is _____
farmed
what are tuna caught with and how are they stored?
large seines, surface longlines, or gill nets. they are stored in freezers on the boats to travel long distances
____% of the worldwide catch is bycatch. a good portion of bycatch, however, goes unreported
25%
how far do exclusive economic zones cover and what do they do?
allow nations to protect fishing and other recources 200 nautical miles around their shores
