Deepwater
Map ID Number: Not mapped during the workshop
Location: Throughout the New Zealand Exclusive Economic Zone
Approximate area: Not recorded during the workshop
Description of area:
Depths greater than 1500m.
Biological attributes:
There is a high diversity of deepwater fish species in New Zealand. They are often slow growing with high longevity. Fish sizes generally decrease from coastal waters to the lower continental slopes, however, at depths below 800-1000m there is an increase in the average size of demersal species. Below 1500 m there is a further decrease in the size of most demersal species, while some species take on gigantism (e.g. giant cods (Lepidion spp.), purple chimaera (Chimaera lignaria), sleeper shark (Somniosus sp.)). These deepwater species tend to be more specialised feeders, in part because of their morphological and functional adaptations to great depth, low light levels, and low food availability; populations have lower densities and communities with less diversity. These environments are more stable than the coastal environment, so they are less able to recover from anthropogenic disturbances. Diversity of sharks, rays, and chimaeras (chondrichthyans) is greatest over the con-tinental slope (200-2500m depth). All but one of the 14 chimaera species normally occur below the shelf break. Fifteen species of sharks (20% of the fauna) inhabit the outer continental shelf and upper slope, and 32 species (44%) are found only on the continental slope (below about 200m depth). Twelve percent of rays inhabit the outer shelf and upper slope, and 56% are restricted to the slope. The latter include 15 species of skates and two small, blind electric rays (Typhlonarke spp.). Endemism is particularly high among the skates (94%), which includes 8 undescribed species of Notoraja.
Criteria applied:
Endemism; dependency for other species; representation (i.e. across physical types); extremities of range and adaptation to environment; special conditions and specialised organisms; species with a global distribution but New Zealand is a significant stronghold; special phylogenetic grouping.
Status and management:
There is no specific management for deepwater habitat, but see Seamounts above.
State of information:
New Zealand’s deep waters are poorly sampled, especially below 1500m.
References and further reading:
Anderson et al. (1998), Francis et al. (2002), Merrett and Haedrich (1997), O’Driscoll et al. (2003).