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Marine Ecology Exam 2
Terms in this set (223)
Describe the reproductive behaviors of North Atlantic Lobsters:
1. dominant/large males select best shelters
2. females select dominant male's shelter and moves in
3. Female will molt and then mate
4. After mating, female waits for shell to harden and then moves out
5. other females in waiting move into shelter with olfactory cues
Describe the reproductive behavior of Opossum Shrimp:
- no active searching for mates or pre-spawning behavior
- females secrete pheromone after molting and any nearby male is attracted
- external fertilization
What are the 2 basic strategies for repro?
Iteroparous and Semelparous
What is iteroparous reproduction?
spawning possible more than once--> most fishes and invertebrates
What is semelparous reproduction?
spawning only once, then death--> pacific salmon, some eels, cephalopodspacific salmon, some eels, cephal
What are the pros and cons of iteroparous reproduction?
Pros: Many chances to pass on genes, better in an unpredictable environment
Cons: Must be long-lived; expend the energy multiple times
What are the pros and cons of semelparousreproduction?
Pros: Maximum investment
Cons: Unfavorable conditions may wipe out entire brood; only get 1 chance
What is a promiscuous mating system?
little or no mate choice
What is a polygamous mating system?
one sex has multiple partners
- polyandry: : one female, several males - rare
- polygyny: one male, several females - common
What is it called when a female has multiple mating partners?
What is it called when a male has multiple mating partners?
What is a monogamous mating system?
mates stay together, exclusively
What kind of organisms are promiscuous?
- organisms that live in large groups
- organisms with high fecundityorganisms with high fecundity
- sedentary organisms
EX: dolphins, schooling fish, corals, krill
What kind of organisms are polygamous?
- none to some parental care
- nest guarding
EX: urchins and sea turtles (polyandry); seals and sea lions (polygyny)
What kind of organisms are monogamous?
- defense of territory / resource
- parental care by both parentsparental care by both parents
- relatively rare in marine organisms
EX: Albatross, angelfish, puffins, seahorses (for mating season), penguins, clownfish
What is an example of an extreme/atypical mating system?
- Males rely on females for nutrition - internal organs degenerate with organs degenerate with exception exception of testes
What is gonochoristic?
gender fixed, determined earlygender fixed, determined early
What is hermaphroditic?
either sex, both, or sex change
What is sequential hermaphroditism?
sex change during life
EX: sponges, some fish (porkfish, grouper, lyretail coralfish, clownfish)
What is simultaneous hermaphroditism?
eggs & sperm at same time
EX: some worms
What is a trade-off of parental care?
Few, but high quality OR
Many, but low quality
Fertilization in inverts via a spermatophore:
- Can be stored internally or attached externally
- May provide nutrients to female
- May prevent subsequent matings by other males
- Decreased surface area
What is metamerism?
serial repetition of body regions--> more opportunity for appendage specialization
- Rare in invertebrates
- Becomes more common in "higher" vertebrates EX: sharks, sea turtles. cetaceans
- More common in marine fishes
- Also known as broadcast spawners
- Some benthic fishes will do it
- high fecundity
- gametes released into current
- settle to substrate after fertilization
- gametes can be stored internally
- fertilization is external
- fert. eggs carried (usually by females) until hatching
- more common in invertebrates
EX: spiny lobsters, crabs
Do external brooders exhibit parental care?
parental care of juveniles after hatching does occur but is rare, mostly in fishes
EX: cardinal fish, seahorses
- Occurs via splitting, budding or fragmentation
- Generally rare, but more common in colonial organism at the cellular level of organization
EX: corals, sponges, anemones
Describe the jellyfish lifecycle:
fertilized egg--> planula--> attached planula--> polyp--> budding polyp--> ephyra--> adult
Describe the oyster lifecycle:
fertilized egg--> free-swimming larva--> spat--> pedivelliger--> adult
Describe the blue crab lifecycle:
fertilized egg--> zoea--> megalops--> immature crab--> adult
-migrate in/out of estuaries
Describe the mutton snapper lifecycle:
fertilized eggs--> larvae--> juveniles (mangrove)--> juveniles (seagrass beds)--> subadults (coral reefs)--> adult
What is viviparous development?
The embryo develops inside the mother and the mother gives a live birth.
- umbilical cord or other nutrient source
- marine mammals
What is oviparous development?
animals that lay eggs, with little or no other embryonic development within the mother.
- many fish
What is ovoviviparous development?
animals develop within eggs that remain within the mother's body up until they hatch or are about to hatch.
What abiotic factors affect repro in the ocean?
Moon, currents, tides, seasons
What biotic factors affect repro in the ocean?
Pheremones, predation, competition for mates, olfactory cues
What is the general pattern of larval dispersal in marine organisms?
egg--> larvae--> juveniles--> adults
Why do most FW organisms not have a larval stage?
- FW doesnt have as much movement (currents, tides, etc)
- Much more localized
- FW systems are smaller
- Organisms have smaller body sizes
What are the 2 majors things triggering eggs to hatch?
Water temp and oxygen content
What triggers eggs to hatch?
Tide conditions, time of day, seasonal current changes
EX: flat damselfish hatches at sunset of night of strongest ebb tide to help mvmt offshore
What determines the length of a larval stage?
Resource needs in relation to currents (food, habitat)
What is a lecithotrophic larvae?
with yolk sac, no digestion--> NON-FEEDING
What is a planktotrophic larvae?
FEEDING larvae, digestion (disperse over greatert distances)
Which larva type disperses over shorter distances?
Lecithotrophic; limited by nutrients
Which larva type disperses over longer distances?
Larvae of different taxonomic groups:
1. Zoea - Crustaceans
2. Amphiblastula - sponges
3. Veliger - some molluscs
4. Leptocephalus - some fishes
5. Hard corals - planula
What factors must larvae overcome?
must find food, protection, and a suitable home
Why is larval ecology important?
an understanding of larval ecology is central to understanding how marine communities persist
independent morphologically different stages that develop from fertilized eggs and must undergo a profound change before assuming adult features
when larvae fall out (leave) the water column, select habitat, and undergo metamorphosis. This is usually brought on by cues from the environment
The larvae that have (1) dispersed and settled, (2) metamorphosed successfully, and (3) survived to be detected by the observer
female produces many (103 - 106) small eggs, larvae feed on plankton, long dispersal time (weeks)
Lecithotrophic larval dispersal:
female produces fewer eggs (102 - 103), larger, larvae live on yolk, short dispersal time (hrs-days usually). More energy is put into each egg
female lays eggs, or broods young, juveniles released and crawl away
EX: octopus, some fish, krill, copepods
larvae that live in transoceanic currents (are always planktotrophic larvae)
Are veliger larvae lecithotrophic or planktotrophic?
a larval type only found in Mollusks. Torsion, twisting of the body that produces the spiral shell, is already taking place or will very soon after hatching. This type of larvae is usually ready to settle within days of hatching, and is unique to mollusks.
What are some factors that help in dispersal?
- Winds that wash larvae to shore
- Internal waves - bring material and larvae to shore
- Eddies that concentrate larvae in spots
- Behavior - rising to the surface at certain times of day, or with the rise of the tide. Most larvae have some ability to control the direction in which they disperse.
What are some examples of using timing for increased larval survival?
- larvae in intertidal areas that move at night are selected for avoiding predation
- Grunion spawning on beaches; timed with highest spring tides of Spring
- Coral reef damselfish lay eggs at dawn; larvae hatch 4 sunsets later (avoid predation). Egg production timed so that hatching is with the ebb tide which sweeps larvae offshore (lowers predation)
What are some abiotic factors affecting larvae success?
Light, salinity, chemicals, currents, substrate, depth, pressure
What are some pre-settling problems that larvae encounter?
- loss to inappropriate habitats
What helps larvae determine settlement?
chemical and physical cues (active choice)
Why do most larvae prefer settlement sites with bacteria present?
These are usually healthier and with higher productivity
What is gregarious settling?
Where larvae settle on adults
EX: oysters, barnacles
What are the costs and benefits of gregarious settling?
Benefit: ideal settlement location
Cost: Higher competition for food
What is considered "recruitment" ?
The larvae that have
(1) dispersed and settled
(2) metamorphosed successfully, and
(3) survived to be detected by the observer
Why do larvae disperse?
- High probability of local extinction; best to export juveniles
- Spread your young (siblings) over a variety of habitats; evens out the probability of mortality
- Maybe it has nothing to do with dispersal at all; just a feeding ground in the plankton for larvae
Are planktonic feeding larvae most common in higher or lower latitudes?
What does larval dispersal allow for?
- Allows species to invade new areas
- Avoids crowding (areas where space is the limiting factor for population growth)
What does sea ice coverage affect?
Deep water cycling
What are the 3 phases of glacier formation?
2. moving forward
What are ice packs?
Formed from the freezing of seawater in autumn with the surface of the water is cooled to below -1.8°C (freezing point of s.w.)
NOT the same as glaciers and icebergs
What are the steps of ice pack formation?
1. Grease ice forms- plankton stick to crystals
2. Ice pancakes- 5-10cm diameter pieces
3. Super pancakes- 20-50cm thick, meters across
4. Ice floes- once formed, continually being moved apart.
What are brine channels?
small salt water channels in the ice floes; organisms may live in them
What is limiting factor in polar primary production?
To survive in the arctic, organisms must be tolerant to:
- cold temps
- low light
- high salinity
What organisms are important to the polar microbial food web?
bacteria, flagellates, diatoms, rotifers, turbellarians
What organisms are grazers along ice packs?
amphipods, copepods, krill, ice fish
What is the keystone species in Antarctica?
Southern Ocean Krill
- Primary food for squids, penguins, seals, baleen whales
- Distribution patterns of krill are closely linked to ice-sea conditions
Which has substantial terrestrial food sources, arctic or antarctica?
Arctic (no terrestrial food on antarctica)
Which has land mammals, arctic or antarctica?
Arctic (no land mammals in antarctica)
Which has herbivorous and insectivorous birds, arctic or antarctica?
Which can exchange water with the Indian, Atlantic, and Pacific oceans, arctic or antarctica?
Antarctica (Arctic has 2 opening- Bering and Fram straits)
Which has ice that can last several years, arctic or antarctica?
Arctic (Antarctic ice only lasts 1 year)
Which is geographically isolated, arctic or antarctica?
Which has an ice-free coastal zone in the summer, arctic or antarctica?
Which has relatively high plant and animal diversity on land, arctic or antarctica?
Which has higher marine benthic diversity, arctic or antarctica?
Which is deeper, arctic or antarctica?
Antarctica (mean depth 4000-6500m)
Arctic (mean depth 1800m)
Which has surface waters rich in nutrients year round, arctic or antarctica?
Does ice have a stronger or weaker impact with regards to the rocky coastline?
- Sea-ice really good at scouring a rocky coastline- down to 500m in some cases
- Areas of HIGH disturbance.... Can take place in some areas every 50 years
- Less prevalent in the Arctic compared to Antarctic
What organisms live on polar rocky coasts?
Short-lived, fast-growing microorganisms
What is the keystone land species in the arctic?
What are some defining characteristics of the tundra?
- no large trees, mostly lichens
- slow decay rates
- cold and windy
What are some examples of tundra plants?
What are some examples of tundra animals?
What is the keystone species in the marine arctic food web?
Polar cod; dependent on edges of ice floe
What are some defining characteristics of antarctica?
- Covered in ice and snow - little ice-free land for plant colonization
- High winds all year round
- A virtual desert inland, several meters of snow fall along coast annually
- No trees or shrubs, only two species flowering plants; Moss and lichen in wetter areas
- Greatest species diversity along western side of Antarctic Peninsula, where climate is generally warmer and wetter.
How do organisms deal with the cold in polar regions?
- Migration; energetically expensive with no guarantee of food EX: most mammals
- Resistance; dense fur, "anti-freeze" agents in blood EX: musk ox, caribou
- Hibernation; polikotherms (endotherms) and homeotherms (ectotherms)
Why are polar regions important to many birds and mammals?
Reproduction; may give birth to young on the ice in winter/early spring
Why do birds and mammals reproduce in the winter/early spring?
- Young then become independent by late summer when food is most available
- Important for penguins as they renew plumage
- Also important for predator avoidance
- food availability (Arctic: Arctic Cod, Antarctic: Krill)
How do puffins obtain food?
surface dives to swim after small fish, catching and holding in its bill until it has a full load
- Arranges fish crosswise in its bill using its raspy tongue to hold against the roof of its mouth while catching the next fish
- Roof of its mouth has rearward-pointing spines to help hold the fish
Which species of bird migrates from pole to pole every year?
- nest in polar regions
- eat fish and crustaceans
- can fly for weeks at a time without stopping
How have birds adapted to cold environments?
- Antifreeze eggs; thicker protein layer, lay less eggs
- Cold Feet, warm heart; counter-current exchange
- Cozy homes; insulated tunnels, dens, burrows, etc.
- Dressing down
- Feathered snowshoes; extra long toes with long claws
- Knobbly feet; less of the foot in contact with ice
- Posing for warmth; penguins huddling
What mammals are present in polar regions?
Polar bears, whales, seals, walruses
What is the southern limit for polar bears?
the southern most extent of sea-ice
Where do most polar whales live?
Most around edges or in open polar water. Not many whales can live deep within the pack-ice
Why can Weddell seals live beneath the pack-ice?
Use their sharp teeth to keep breathing holes open
Why might the antarctic have higher endemic benthic species than the arctic?
Much older, deeper
Where is polar gigantism mainly found?
In benthic groups, especially molluscs, crustaceans
What causes polar gigantism?
Thought to result from slow growth rates in low temperature waters and the increased dissolved oxygen concentrations in the water
What limits how large an organism can grow?
The physiological limit on the size of an organism is the amount of dissolved oxygen it can get in it's blood; Efficiency and length of the circulation systems also come into play.
Moving along a course
Moving from one region to another
Returning back to a specific point
What are some animals that rely on migration for reproductive success?
Sockeye salmon (lifestyle migration and homing)
Sea turtles (homing)
What is an example of a species that migrates for food acquisition?
- Trail following
- Path integration
- Map and compass navigation
Employed by invertebrates only (ants), release pheromones to follow
Using landmarks to navigate (pigeons), short and long distances, seals and whales spyhopping
Employed by invertebrates only (ants, bees); randomly looking for food, feed, return directly home
Map and compass navigation
Used by long distance migrators (whales and turtles); use earths magnetic field and wavelengths
How do birds use magnetic fields to navigate?
Magnetite receptors in their beaks (iron oxide clusters in beak to receive/transmit pulses from magnetic field)
How might some birds use compass navigation?
Use the sun or stars
How do some birds navigate using olfactory cues?
Detection of dimethyl sulphide (DMS) released from phytoplankton blooms
What are some of the driving factors of marine animal migrations?
Food, suitable breeding area, optimal habitat temperature, development and life cycle pattern, desire for predator-free space for colony-breeding species
How had animal previously been tracked?
Observation of presence or absence in a region
How are animals now being tracked?
- Stable isotopes (carbon tells you what it eats, nitrogen tells you trophic position)
- Various types of tags
- Passive acoustic methods
Why is it important to track animals?
So that better management plans can be formed
What projects has animal tracking been useful in?
- More precise count of white shark population
- Electronic tags have been used to reveal patterns of habitat utilization
- Avoid or mitigate conflicts with oil and gas development, shipping, and military activities
- Listing the Black-footed Albatross as endangered species (US), Sea lions (Aus)
- Potential impacts of climate change
Why can tracking animals that inhabit regions that we don't have access to be useful?
Tags can measure (while on animal):
- temperature, salinity, light, fluorescence, and oxygen
- aligns with animal movements
Tagging of Pelagic Predators (TOPP) Project findings:
- Many migration patterns aligned with changed in the temperature and primary production
- 2 important regions: California Current and North Pacific Transition
What are the 3 main types of tags?
Are satellite tags attached externally or internally?
How do satellite tags work?
Transmitter produces radio waves, which are received by satellite; GPS used to determine position of tag (animal)
What other parameters may a satellite tag measure?
temperature, pressure, etc.--and the data may be transmitted via satellite or stored for later retrieval
Why are satellite tags reserved for animals that surface often?
Antenna on tag must be above water to transmit a signal to satellite
What is a pop-up satellite archival tag used for?
fishery-independent data collection, Used with tuna, marlin, swordfish, mola mola, eels, sea turtles
How does a pop-up satellite archival tag work?
Placed externally and pre-set to detach, rise to the surface and transmit data to the Argos satellite network
How do archival tags work?
- Used to record many types of data, which is stored for later retrieval
- Don't transmit data to any kind of receiver
- Tag may either be implanted or externally attached to animal
When are archival tags useful?
Useful when satellite or acoustic technologies are not possible
How do archival tags determine position?
Can determine position by "light-based geolocation"--light levels data gives coordinates
What are some limitations to using archival tags?
data retrieval often depends on recapture, although some are "pop-up" satellite tags
How to acoustic tags work?
- Utilize sound waves to transmit information
- transmitter and hydrophone
- Transmitter attached externally or internally to animal
- hydrophone is stationary or attached to a ship - may record the signal and store it for later, or convert the signal and transmit it via radio waves to an on-shore (or ship) radio receiver
Which type of tag utilizes a transmitter and hydrophone?
Why use acoustic tags?
- Sound waves travel fairly quickly in water
- Sound waves attenuate much more slowly than radio waves in salt water
- Deep water organisms may be tracked much more easily than in other tagging technologies
Which type of tag is best for deep water organisms?
Which type of tag is used for animals that surface often?
What is a fishery?
- The resource
- The habitat
- The people involved
What are the top 5 fisheries worldwide?
Alaskan pollock, mackerel,
Are most fish harvested near-shore of offshore?
Near-shore, within 200 miles of shore (Upwellings, Continental shelves, and estuaries)
How much of the fish caught is for human consumption?
60%, 40% for animal feed
What is a demersal species?
EX: haddock, flounder, cod
(sometimes called "ground fish")
What is a pelagic species?
EX: anchovy, tuna, mackerel
What percentage of US fisheries are being overexploited?
42% (EX: Orange ruffy, cod, herring)
What is the status of marine fisheries?
In 2004, 52% of world fish stocks were fully exploited, 25% were overexploited or depleted
What is the status of large predatory fish?
Large predatory fish have declined globally by 90%
What is a fisheries collapse?
When the catch level is 10% or less of the potential max
What is an example of a fisheries collapse?
- has never recovered even though is no longer fished
- fishing for other species resulted in catching babies
Pacific abalone: no recovery, no open season
What are the causes for marine fisheries declines?
2. Highly efficient technology
he rate of fish mortality (harvest plus bycatch) exceeds the natural rate of replacement;
#1 cause of fishery declines
Highly efficient technology:
- Fishing vessels and gear
- Radar and sonar
- Electronic navigation
- Aircraft with infrared sensors
- Electronic image intensifiers
EX: ships going from patch to patch, some vessels can remain at sea for months and process fish at sea
The capture of non-target fish or other marine animals in fishing gear
- Animals are stressed and die even when release
- some nets sit for a week
Fishing fleets are larger than necessary to harvest the allowable catch, too many people fishing
What are the 4 main community and ecosystem-level impacts of fishery declines?
1. Fishing down the food web
2. Habitat degradation
3. Trophic cascades
4. Changes in life history traits
What is "fishing down the food web"?
The serial harvest of progressively lower trophic levels
- decreases avg catch sizes
How does fishing gear cause habitat degradation?
Deep sea trawling and dredges used for ground (demersal) fish destroy ecosystems
What is an example of an organism affected by deep sea trawling?
Deep sea corals; live for thousands of years, greater impact than quick growing species
How do fisheries create trophic cascades?
he "domino-like" effect of removal of a top predator; whole ecosystem will suffer
How have some species responded to fishing pressures?
Changes in life history traits
- Females respond to fishing pressure by spawning at an earlier age
- Removal of large females reduces reproductive potential
Why are fisheries declines allowed to occur?
- Government subsidies
- Increasing demand
- Shifting baselines
- Lack of adequate fisheries data
Government subsidies for fishing:
- receive unemployment when not catching enough fish
- tax breaks (fuel and gear)
- paid for vessel use
Can fish continue to feed the world?
NO; with sustainable practices it may be able to continue at the current rate
How it was in the recent past is not necessarily how it was before human activity
- baselines change w/ each generation
Lack of adequate fisheries data:
Effective management requires collection and interpretation of basic biological information on fish species and marine ecosystems
What kind of fisheries data is lacking?
- food along different life stages
- migration patterns/routes
How have fisheries traditionally been managed?
- quotas (total allowable catches)
- gear restrictions (banned gill-netting, mesh size requirements)
- Maximum sustainable yield
What is maximum sustainable yield?
How many individuals can be caught w/out dramatically decreasing the population
What is a major issue with maximum sustainable yields?
- Based on estimates
- easy to overestimate - assuming its always exponential growth
- pressures from outside to catch more
Common during mating/reproductive periods
Why didn't closing the fisheries work for atlantic cod?
- longer maturation periods
- reproduce slowly
What is an example of a fisheries closure resulting a pop. rebound?
Sea scallops on george's bank
- closed in 1994
- by 2010, had 20x the amount at closure
What are some market-based solutions to fisheries management?
- Consumer-based solutions
- Purchase of fishing rights
- Increased use of underutilized species
- Reduce government subsidies
Who certifies seafood?
Marine Stewardship Council (MSC)
What are the criteria for certification through MSC?
- status of target fisheries stock
- impact of fishery on the environment
- how it is managed
Purchase of fishing rights:
Governments may buy out willing fishing permit holders to reduce fishing effort
- NOAA not renewing expired permits and no new permits
What are the top 5 species farmed in the US?
What are the most sustainable aquaculture products?
Farmed organisms that do not consume fish meal are most sustainable
How can aquaculture impact fisheries?
Fish farming has the potential to reduce the pressure on wild-caught fish
Increased use and marketing of underutilized species
Renaming bycatch to sell to consumers
Silver hake = "whiting"
Slimeheads = "orange roughy"
Patagonian toothfish = "Chilean sea bass"
Deep sea angler = "monkfish"
Reduce government subsidies:
Reduction and eventual elimination of government subsidies allows price to be a more reliable indicator of scarcity; will also help in reducing fishing fleet
What management practices are now used for fisheries?
Ecosystem-based Fishery Management: Attempts to sustain healthy marine ecosystems and the fisheries they support
Ecosystem-based Fishery Management:
- Reduce bycatch
- Marine reserves
- Catch share programs
- Ecologically sustainable yield
Extractive activities (fishing, mining, oil drilling) are prohibited in marine reserves
Catch share programs:
Individual Transferable Quotas (ITQs) can be bought and sold; reduces the need for new permits
Ecologically Sustainable Yield (ESY):
- Allows a sustainable harvest that does not shift the marine ecosystem to an undesirable state
- Requires long-term monitoring of all trophic levels
- Requires more complete knowledge of the biology of individual species
- usually less than MSY
What is needed for the future of marine fisheries?
- An ecosystem-based approach
- better collaboration between fishermen, politicians, and consumers
Fisheries Main Points:
- Marine fisheries are an important biological and cultural resource
- Significant numbers of stocks are overexploited or depleted
- Overfishing is a major cause for the decline of marine fisheries
- Traditional fisheries management has not resulted in sustainable fisheries
- New approaches include both market-based and ecosystem-based solutions
What is aquaculture?
Rearing of aquatic organisms under controlled or semi-controlled conditions.
History of aquaculture:
- Tilapia in Egypt (2500 BC)
- Carp in China (2500 BC)
- Carp in England (1500 AD)
- US first hatchery in Oregon (1877)
What kind of bodies of water did aquaculture originate from?
- oxbow lakes
- monsoon waters
- netted coves
Why are fish farmed?
Food, aquariums, bait, natural stock enhancement
What are some commonly cultured crustaceans?
Shrimp, crabs, lobster, crayfish
Commonly Cultured Inverts:
Why Aquaculture Products?
- Control the Food fed, Density, Quality of product
- Sustainable in the face of Finite Resources (overfishing and habitat destruction)
- Diversify farm income
- Proximity (Farms may be closer to local markets)
- Health Consciousness (protein, FA's, micronutrients)
How is aquaculture growing in comparison to other industries?
Aquaculture is growing faster than any other meat industry
- 300 species now cultured
- Tilapia and carp still highest but yields low price per lb.
- 20% are carnivorous fishes
What is extensive aquaculture?
Minimal control, lower density, ponds (third world)
What in intensive aquaculture?
Highly controlled, high density, RAS, raceways, confined (industrialized)
What is monoculture?
one stock, limited investment for feed and equipment, marketing simpler
What is polyculture?
raising 2+stocks together, usually good with fishes low on the trophic scale. If done correctly, can increase production and income.
EX: Sea urchins and salmon, Tilapia and rice patties
What are some of the benefits of aquaculture?
- Decrease pressure on wild fish
- Less expensive than industrial fishing - better human diets & less unsustainable fisheries
- Demand is growing for protein worldwide
What are some of the challanges of aquaculture?
- Disease & parasites; spread to wild fish, antibiotics
- Fish feed
- small gene pool
- invasives - escaped domestic fish
- Loss of natural habitat - invasive captures, farm location (20% mangrove destruction)
- Pollution from concentrated sewage - smother benthos, eutrophication, ↓ DO
What is the main limiting factor in aquaculture growth?
the need to find a high protein artificial feed to support the carnivorous fishes
What are some of the benefits of using plant-based feed in aquaculture?
- Soybean, lupin, and canola yield acceptable growth rates and are half the cost, don't pull from ocean
- more reliable and less chance for diseases to be introduced to the system
Aquaculture Biotechnology Pros:
- cryopreservation of viable gametes eliminated breeding constraints of those stocks that have seasonal cycles
- Controlled sex differentiation
- Genetic selection: reduce fin and head size
differentiationWhat benefit to having a single sex stocks?
- no energy spent on reproduction
- females are usually larger
Aquaculture Biotechnology Cons:
- Escapee's into natural systems
- Drug resistance build-up
Coastal ponds for aquaculture cultivation:
- Natural ponds are used but not many of them
- Some have created artificial ponds by taking our mangrove forests and developing (Central Amer.)
- Have to closely monitor stocking of the ponds to avoid overstocking and keeping a stable oxygen supply
Cage systems for aquaculture cultivation:
- Can closely monitor stocks
- Can be suspended in well-aerated water
- Still relatively coastal and only a few areas are good for this: Norway, Scotland, Canada, Chile
- Enclosed tank and raceway systems
- On land, not coast, enclosed
- Better for less disease, biosecurity, and no other environmental problems arise
- Hydroponics can be used to grow more products
Offshore automated fish cages:
- Fishes fed automatically, can be lowered if high wave action, and less navigation hazards
- Can also be raised for maintenance, harvesting
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