state the habitat of larval wild shrimp and the advantages to living there
- surface waters of the ocean
- currents can disperse them to different habitats; mangroves
- can avoid competition for resources
- receives d.o. and nutrients at the surface
- can avoid cannibalism
- warm waters at the surface = faster development
suggest two long-term economic disadvantages to local people when mangroves are destroyed
- loss of local fishing
- loss of food sources
- loss of wood source
- loss of farmland
discuss the ecological importance of mangroves
- they act as nursery grounds for juveniles
- they enhance fisheries as juveniles are able to mature
- they prevent coastal erosion as their roots absorb wave energy
compare the life cycle of a crustacean to a marine mammal
shrimp
- complex life cycle; larvae and metamorphosis
- external fertilization; develops in eggs
- no parental care
- 1000s of eggs
- live in various habitats
whale
- simple life cycle; no larvae or metamorphosis
- internal fertilization; develops in the womb
- the mother nurses her calf
- typically one calf born
- lives in the open ocean
state two reasons why shrimp are considered to have a complex life cycle
- larval stages are present
- the larval states metamorphosize over time
describe advantages and disadvantages of internal fertilization
Advantages: increased chance of egg fertilization, increased chance of survival to birth and adulthood because the fetus is protected in the womb
Disadvantages: fewer offspring are produced, a mate is necessary which means competition, mothers nurse their young which needs a lot of energy
explain why there’s a large # of gametes released by shrimp
- they’re external fertilizers
- few eggs will be fertilized meaning a loss of gametes
- the release of more eggs increases the chance of fertilization
state the habitat of adult shrimp
benthic seafloor
suggest why whales have a long gestation period
whales are born large and well developed
most tuna fisheries are unsustainable. state the meaning of the term unsustainable.
when more fish are harvested than recruited into the population
explain why mangrove habitats are advantageous to juvenile shrimp
- mangroves have high biodiversity so there’s plentiful food supply
- due to the tide pattern and rivers, nutrients are trapped by the mangrove roots
state the meaning of the term metamorphosis
changing from larval form to adult form
explain how the creation of an MPA could improve the stocks of fish and crustaceans in coastal areas
- allows juveniles to reach sexual maturity so more breeding will occur, which leads to increased recruitment
- spillover will occur; species move out the MPA where they can be caught by fishing vessels
list at least 3 conservation measures to help fishing remain sustainable
- restrict the fishing locations
- restrict fishing season
- restrict mesh size
- restrict the mass of fish that can be caught
discuss the impact of SONAR on fish stocks
SONAR can detect the size and direction of movement of the shoal, therefore, catching the entire shoal= overfishing = fish stocks decline
describe how salmon are grown to maturity in sea cages, using extensive aquaculture
- smolts are put into coastal pens in an estuary and are fed high protein pellets regularly
- fish of different ages and sizes are kept in separate cages
- pesticides, antibiotics, or cleaner fish may be added to cages
- fish can be harvested after 1-2 years
discuss one pro and one con of each of the following monitoring methods: satellite monitoring and inspection of catch
Satellite monitoring
Pros: shows the exact boat position, can track multiple boats at a time, and can monitor boats 24/7
Cons: not all boats have satellite technology on board and may be turned off
Inspection of catch
Pros: can i.d. the volume of catch, the species caught, and any illegal catch
Cons: bycatch may be disposed of before inspection
tuna catches are estimated to be under-reported by ~28%. suggest why stock assessments are difficult to collect and under-reported
- many species have unknown breeding grounds
- captains may falsify logbooks to avoid getting fines or having restrictions if they are over quota
- juveniles may be caught as bycatch and thrown back in dead and not reported
- lack of on board observers to monitor catches
- there’s no data on natural mortality
discuss the impact of purse seine fishing on fish stocks
- purse seine vessels encircle and capture the entire shoal
- bycatch rates are high and may will be dead or dying when thrown back into the ocean
describe the process used for the intensive aquaculture of shrimp
- adult shrimp are kept in indoor tanks
- fertilized eggs are collected and placed into brood tanks
- shrimp larvae are fed phytoplankton
- postlarval shrimp are placed in nursery ponds
- shrimps are grown out in outdoor shallow ponds
- antibiotics and pesticides are used to reduce bacterial infections
- environmental factors are heavily controlled
an aquaculture company is raising non-native fish in a sea cage 2km away from the coast. suggest reasons why local wild fish populations might disappear
- excess food, as well as feces, will fall to the bottom and decompose
- oxygen levels will decrease, causing possible death of benthic fish
- excess nutrients in the water can cause eutrophication
- some algal species release toxins that can kill fish, causing an imbalance in the food web
- chemicals that are sprayed on cages to control algae and biofouling can harm the fish as well
- diseases and parasites can spread to wild fish from farm raised fish
state two long term sociological impacts of putting restrictions on fishing
- sustainable fish stocks
- future employment and money into economy
discuss the impact of benthic trawling on fish stocks and habitats
- benthic trawler drag a weighted net along the sea floor, targeting bottom feeders
- the nets catch all organisms in its path, resulting in excessive bycatch
- habitat destruction is common because of the unsettling of sediments
- the unsettling of sediments increases turbidity which may lower productivity and clog gills
describe how integrated multi-trophic aquaculture can help reduce the negative impacts of aquaculture
- fish waste can be eaten by lower consumers and producers, this will result in less bacterial decomposition
- excess nitrates and phosphates will also be absorbed, lessening the risk of eutrophication
