Week 6

• Global demand for fish as it is a nutrient rich source, capture fisheries and aquaculture has significantly increased. However, aquaculture is expanding more as the fisheries are being depleted.
• Uses of fish meal

  • Animal feed
  • Fertilisers to feed other fish
  • Fish oil, supplements
• Commercial fishing is worth $896 mil to NZ economy, creating a significant number of jobs, also informal economy with people fishing and diving.
• Quota management system


  Sets a total allowable commercial catch, for each year. Different fishing companies purchase quota.
• Customary management of fish by iwi

  Sometimes Mātaitai, reserved for local use
• Destructive commercial fishing methods

  • Longlines
  • Trawling
  • Dredging
• Impacts of destructive fishing methods

  • Sediment is disturbed impacting photosynthesis
  • Corals are damaged
• Bycatch


  Deaths of non-targeted species
• Bycatch


  Leading to changes of diversity e.g snapper and kina situation in Hauraki gulf which is now a kina barren
• Common bycatch


  • Dolphins
  • Seals
  • Fish
  • Shellfish
  • Seabirds
• Marine protected areas


  • Marine reserves- highest protection, no fishing allowed
  • Marine mammal sanctuaries- restricted commercial and recreational fishing
  • Recreational fishing parks (proposed) for Hauraki Gulf and Marlborough sounds however is not progressing
• Aquaculture is the fastest growing industry, 20,000 ha of allocated water space
• Problems with aquaculture


  How to share the coast and resources
• NZ aquaculture


  • Salmon
  • Oysters
  • Mussels
  • Paua
  • Algae
  • Carp
  • Crayfish
• Adverse effects of aquaculture

  • Benthic accumulation of debris
  • Alters seafloor/habitats, smothers benthic species
  • Increase of nutrients which can cause algal blooms
  • Biosecurity risk - creating conditions for invasive species or disease
  • Noise, light, entanglement impacts on mammals and seabirds
• Alternatives/mitigation for aquaculture


  • Chemicals used can alter water chemistry (pH), which can stress and kill organisms
  • Impacts from escaped fish on the environment and interacting with wild fish
  • Multi-species aquaculture - mimics natural food chains and brings a range of species together which feed on the waste products of one another, decreases waste products and risks of algae blooms
• Harvesting of fish through commercial fisheries and aquaculture is increasing rapidly. However, there are detrimental impacts on marine life and environment. Mainly dredging, trawling and by-catch from commercial fishing and increase of nutrients, chemical alteration and accumulation of debris from aquaculture.
• 34% of coasts are at high risk of degradation from development
• Impacts of coastal development

  • Loss of habitat leads to decreased biodiversity
  • Increased harvest of kai moana and population
  • Inputs of contaminants
  • Impacts on tangata whenua
  • Increased conflicts between different activities
• Reclamation has been a significant problem: filling in of harbours and estuaries
• Need to think about how these reclamation actions just move the damage elsewhere
• Lots of Auckland viaduct area is all reclamation
• Land-based sources of pollution

  • Waste water treatment effluents
  • Stormwater
  • Litter
  • Rivers
• Pollutants in stormwater


  • Toxic metals
  • Oil and fuel
  • Nutrients and pathogens
  • Sediment
• Pollutants in wastewater


  • Septic tanks, sewage overflow
  • Nutrient and microbial pathogens
• Light and noise can disrupt physiological and biological processes, and can influence predation
• Marinas


  • Occupy significant space
  • Water and sediment contamination from sewage, fuels, anti-foul
  • Alters benthic habitats
  • Alters water circulation and flow
• Mahinga kai is important as an indicator for the mauri (lifeforce) of the environment
• Due to pollution becoming more common, people are losing their connections to mahinga kai