Topographic generated soft sediment refugia
Map ID Number: Not mapped during the workshop
Location: Bay of Plenty and potentially throughout the Exclusive Economic Zone at various depths
Approximate area: Not recorded during the workshop
Description of habitat type:
This habitat is comprised of remnant areas of shelf slope sediments that have remained free of bottom trawling by virtue of their proximity to topographic features. The areas are undisturbed and unfished, but are otherwise representative of shelf and slope sediment habitats. The sizes of the refugia exist on a range of scales, from less than 1 km to tens of kilometres. Such areas are likely to occur throughout the New Zealand Exclusive Economic Zone at various depths. Examples of features that prevent trawling include rocky outcrops or canyons, cableways, and explosives dumping grounds.
Biological attributes:
Soft sediment refugia have high species diversity (including muricid gastropods) and the full range of population size and age structures.
Criteria applied:
Degree of disturbance; unusual degree/ proportion of biomass
Status and management:
The refugia are probably now the only sites in northeastern New Zealand that contain unmodified slope fauna and are likely to be uncontested areas for conservation status. If not conserved, these refugia are likely to decrease in number and size as fishing technology develops to allow trawling in areas with some rocky outcrops.
State of information:
The fisheries trawl database (owned by the Ministry of Fisheries, administered by NIWA) has good records of trawling intensity on scampi grounds on different areas. Interrogation of this database in combination with the latest NIWA swath map should identify the exact location of refuges from trawling.
References and further reading:
Cryer et al. (2002).