2.a. Biological resources within oceans can be used in sustainable or unsustainable ways

what are krill

• small shrimp-like crustaceans that can live for up to five years.

why are krill seen as a keystone species

• they underpin the entire Southern Ocean ecosystem. top predators rely directly on krill for food.

• they are also a renewable biological resource because they can replenish their population if harvested sustainably.

 

krill habitat

 

• they inhabit the upper part of water column. they can swim up and down but not against currents

krill's role in the food chain

• they are primary consumers

• they feed on plankton

• they are a food source for whales, seals, dolphins, fish, birds etc

krill population

 

• they exist in swarms of up to 2 million tonnes

• the biomass of krill is estimated to be more than the human race

The use of krill by humans

• health supplements e.g. omega-3 oil

• food for fish farms

• bait for fishermen

• pet food

 

the use of krill for the environment

• they help to sequester carbon by eating carbon-rich phytoplankton near the surface and excreting it when they sink to lower, colder water to escape predators

threats to krill

• warming sea temperatures - krill grow quicker in colder water

• ocean acidification - affects early life stages of krill, for example ability for eggs to hatch and larvae to grow

 

how has modern fishing technology impacted human use of krill

• modern super-trawlers use suction technology to continuously pump krill out of nets while at sea.

• this prevents krill from being crushed, allowing for omega-3 extraction.

• however it dramatically increases harvest efficiency and the threat of localised depletion.

when did commercial harvesting of krill begin

• in the 1970s

what human activity have krill become victim to?

• boom and bust fishing

• stocks are fished to near extinction, causing the population to crash

• the population then recovers, only to be overfished to near extinction again

stakeholders involved in krill farming

• countries - governments and fishing communities

• consumers - health food companies, fish farms, sport fishing

• environmentalists

• international organisations such as the CCAMLR (convention on the conservation of antarctic marine living resources)

which 5 countries are currently harvesting krill

• norway - half of annual catch

• china - 18%

• south korea - 18%

• chile

• ukraine

CCAMLR's role

 

• set up in 1982 to monitor and regulate commercial fishing of krill

• it is trying to establish catch limits

conflicts between stakeholders

• many ACs have scientific interests in the Antarctic so they don't want the ecosystem to collapse

• however china wants to develop maritime power and feed its large population

resilience and thresholds for krill farming

• krill shoals can be measured using sonar surveys

• the current total allowable catch (TAC) threshold for krill is 620,000 tonnes per year

why is spatial concentration of fishing a threat?

• over 90% of krill harvesting occurs in Area 48 because it is ice-free and easily accessible.

• even if the overall global quota is not exceeded, localised depletion near land-based breeding colonies starves penguins and seals during breeding seasons.

is the population of krill going down

 

• there is growing evidence that krill stocks have dropped severely since the 1970s

• some research suggests a decline by as much as 80%

• this is due to warming seas

• warming seas mean that sea ice melts. algae on the underside of this sea ice are an important nursery for young krills, so if the sea ice melts this causes a drop in the population

How the values of stakeholders influence the use and management of krill

• environmentalist groups value biodiversity and ecosystem resilience, so they advocate for MPAs and catch limits.

• on the other hand, commerical fishing nations like china and norway value economic growth, food security, and market expansion.

How the attitudes of stakeholders influence the use and management of krill

• groups who want to conserve krill view it as a critical species that must be protected to prevent the collapse of the entire food web in Antarctica.

• on the other hand, groups who want to exploit it view krill as an under-utilised, highly abundant biological resource that can solve food and pharmaceutical demands.

How the socio-economic status of stakeholders influence the use and management of krill

• high income, developed countries are driven by consumer demand for products so they are willing to fund high-tech fishing vessels

• developing countries are driven by national food security needs and rapid population growth, making them resistant to strict catch quotas.

How the political context of stakeholders influence the use and management of krill

• the antarctic treaty system and the CCAMLR can block marine reserves and lower catch limits

• however countries who believe in their sovereignty want to harvest krill because they believe it is their right

Key thresholds to initiate management

• CCAMLR sets a trigger level (currently 620,000 tonnes/year in Area 48) to prevent localized depletion before reaching the overall precautionary limit

The resilience of krill

• krill have extremely large population size and rapid reproduction. if fishing is properly managed, they can recover quickly.

• however, they have low resilience against climate change.