Sea urchin aquaculture

Question 1

What aspects make sea urchins a valuable aquaculture species?

Answer 1

• Roe is a delicacy -> extensively fished
• world production mostly comes from the wild
• landings peaked in 1995 (108,974 tonnes of landed urchins)
• dropped to 27% by 2001
• 80% of worlds production consumed in Japan (6 species on the market)
• programs include: re-seeding, habitat modification, seasons closed, max size, etc
• re-seeding is sophisticated -> four years to grow to commercial size

Question 2

Describe the production cycle of urchins

Answer 2

1. Broodstock
2. spawning
3. fertilisation
4. larval rearing/settlement
5. spat rearing/weaning
6. growout
7. seabased in rock pools or cage culture

Question 3

What are technical challenges for rearing sea urchins?

Answer 3

1. dietary needs of different juvenile stages still unknown
2. low postlarval survival rates
3. larval settlement varies
4. difficult to produce sufficient numbers of viable animals of 10 mm
5. needed water flow, water quality and tank design still not fully understood
6. disease identification and treatment is particularly difficult area with little work done

Question 4

How do sea urchins reproduce?

Answer 4

• Fusing of a haploid sperm cell with a haploid egg cell to form a diploid zygote
• Can be internal or external
• Requires exact timing and recognition

Question 5

What is roe enhancement?

Answer 5

The sea urchins are harvested from the wild and kept in an aquaculture system for about 12 weeks. Because of the conditions in an aquaculture system, at the end of the 12 weeks the animals have significantly increased roe content.

Using roe enhancement, significantly more roe can be produced from the same number of animals from the wild.

Question 6

What is a great and sustainable use for sea urchins in aquaculture?

Answer 6

Integrated Multi-Trophic Aquaculture

Question 7

What aspects make sea cucumber a valuable species for aquaculture?

Answer 7

Beche –de –mer or Trepang
• Apostichopus japonicus best
US$2,950/kg dried
• 50+ tropical species traded
• Holothuria scabra most
common US$115-640/kg dried
(large US$1,670/kg)
• Golden sandfish H. lessoni
US$240-790/kg

Question 8

What are the key knowledge gaps remaining in the mariculture of sea cucumber?

Answer 8

1. Genetic effects of hatchery and stocking practices
2. Broodstock conditioning and egg quality
3. Optimal density of larvae for best settlement per tank
4. Feeding ecology of larvae and optimal microalgae diets
5. Optimal protocols of disease and parasite treatments
6. Stocking density, feeding regimes and water quality management in earthen ponds
7. Co-culture opportunities and viability at various sizes of sea cucumbers
8. optimal habitats for release into sea pens or for ranching
9. suitable stocking densities in the sea as a function of habitat features
10. Effects of behavioral conditioning and acclimation on post-release survival of juveniles
11. Strategies for improving governance and communication
12. Comparative analysis of benefits from farming and sea ranching

Question 9

What are the aspects of the NZ sea cucumber species in regards to aquaculture?

Answer 9

• Shallow subtidal to 100m+
• Sediment feeder
• QMS 22 tonnes for the entire fishery
• US12/kg greenweight
• Suitable for ‘polyculture’ with green shell mussels
• Sexual reproduction, sexes generally separate
• Some hermaphrodites have been found.
• Sex ratio is 1:1.Reproductive season is from
October to February, and periodicity
of spawning follows full moon; spawning may occur
repeatedly during a single reproductive season