Protection measures implemented by New Zealand for vulnerable marine ecosystems in the South Pacific Ocean

Interim measures for bottom fisheries adopted by the South Pacific Regional Fisheries Management Organization (SPRFMO) require participants to limit bottom fishing to currently fished areas and prevent significant adverse impacts on vulnerable marine ecosystems (VMEs). The New Zealand bottom trawl footprint consists of two hundred 20 min latitude × 20 min longitude blocks trawled over the period 2002–2006 within which New Zealand flagged vessels reported 11 425 tows, primarily targeting orange roughyHoplostethus atlanticus.

Past effort and seabed impact levels differ substantially between these blocks, ranging from lightly (<3 tows block–1) to heavily trawled (>50 tows block–1), with a maximum of 1417 tows in the most heavily trawled block. Effort data were used to stratify the bottom trawl footprint into 3 effort tiers as the basis for a management approach tailored to levels of past impact: (1) adequate and representative spatial closure of areas likely to support VMEs, with emphasis on less impacted areas; (2) a move-on rule in areas where likelihood of encounter with a VME is unknown; and (3) constraining fishing effort to remaining open areas most impacted by past fishing.

Sixty-two lightly trawled blocks were closed to prevent impact in these areas; 69 moderately trawled blocks were subjected to a move-on rule; and 69 heavily trawled blocks were designated as open to fishing. A further 20 blocks were closed to provide representative protection within the moderately and heavily trawled tiers.

In the absence of seabed biodiversity data, biologically important physical factors, primarily depth range and topography, were used to select interim precautionary closures and to evaluate representativity of closed in comparison with open areas. Geospatial analyses are presented on the distribution and representivity of seabed depth within open, move-on and closed blocks in each fishing area in comparison with the overall SPRFMO Area.