National environmental indicators

The four national environmental indicators for oceans are:

• fish stocks under the quota management system

• seabed trawling in deep waters

• water quality at coastal swimming spots

• marine areas with legal protection.

Understanding how these indicators change will allow us to respond better to existing and emerging pressures on our marine resources.

Fish stocks under the quota management system

The first indicator provides information on fish stocks under the quota management system. To report on this indicator, the following are measured:

• proportion of total commercial catch (by weight) from assessed fish stocks under the quota management system

• status of assessed fish stocks under the quota management system.

Assessed fish stocks

Assessed fish stocks are fish species for which there is enough information to scientifically determine the status of the stock.

Each year, some of New Zealand’s fish stocks are assessed to determine the status of the stock relative to a target level and to ensure the total allowable catch for that stock is set at a sustainable level. Assessment of a fish stock requires significant amounts of data, so it is not always cost-effective or practical to conduct full assessments of all stocks. Therefore, the most valuable and most vulnerable species in any given year are prioritised for assessment.

Status classification

The status of New Zealand fish stocks are classified as:

• near or above target biomass levels: the stock is highly likely to have been sustainably fished

• probably near or above target biomass levels: the stock has probably been sustainably fished

• possibly near or above target biomass levels: the stock is more likely than not to have been sustainably fished

• below target biomass levels: the stock is likely to have been overfished, and recovery plans are in place

• unknown: there is not enough data to ascertain the status of the stock.

Seabed trawling in deep waters

The second indicator provides information on seabed trawling in deep waters. To report on this indicator, the following are measured:

• the area ‘swept’ (the area trawled over by a vessel towing gear along or near the seabed) by commercial trawlers, which are required to report their position by latitude and longitude

• the types of fish expected to be found in areas that have been swept.

This indicator shows only where there has been seabed trawling and the amount of trawl effort in those areas. It does not provide any information on the impact of the trawl on the sea floor environment.

Data collected from Trawl Catch Effort Processing Returns

Seabed trawling in deep waters is reported on using data collected from commercial forms called Trawl Catch Effort Processing Returns (TCEPRs) from 1990 to 2005. These returns are required from all commercial trawlers longer than 28 metres and some smaller vessels that are required to report their position.¹⁰

Most small vessels do not have to complete TCEPRs, so an estimated 3.5 million dredges and trawls are not reported over the same period. In some inshore areas, the effects of dredging and trawling by small vessels can be significant.

Data reported for ‘fishing years’

Trawling effort is reported by ‘fishing year’, which runs from 1 October to 30 September of the next year. For ease of reference, a fishing year takes its name from the second of the two calendar years. For example, because most of the 1989–1990 fishing year is in 1990, it is referred to as the 1990 year.

Reporting on trawl effort

About 970,000 TCEPR trawls were reported in the 16 years from 1990 to 2005. These include bottom trawling and trawling using mid-water gear close to the seabed. The area swept for each trawl is estimated using the reported start and end positions of the trawl, and estimates of the ‘doorspread’ (effective width) of the trawl gear.

To report on trawl effort, the area inside the Exclusive Economic Zone (EEZ) is divided into a grid of 25-square-kilometre cells (National Institute of Water and Atmospheric Research, 2007). For each cell, the sum of the area swept (square kilometres) can be calculated. In a particular fishing year, a cell may have a total swept area of zero square kilometres (that is, it was untrawled) or, for example, 100 square kilometres, indicating that, on average, the area of the cell was trawled four times.

The trawl effort can then be analysed against the Demersal Fish Community Classification (see box ‘More about the Demersal Fish Community Classification’) to see what types of fish community are likely to have been most affected by seabed trawling in New Zealand.

Water quality at coastal swimming spots

The third indicator provides information on water quality at coastal swimming spots – referred to as ‘recreational water quality’. To report on this indicator, concentrations of enterococci bacteria at coastal swimming spots are measured.

Enterococci indicate the presence of faecal material in coastal waters. During summer months, concentrations of enterococci are measured, usually once a week, at monitored beaches, and the results are compared with national guidelines.

Recreational water quality can be affected by effluent run-off from farmland and human wastewater discharges. Seawater that has been contaminated with human or animal effluent can carry a variety of disease-causing organisms. These can pose health risks to people using coastal beaches for activities like swimming, sailing, and surfing. Very young children, the elderly, or people with impaired immune systems are particularly vulnerable.

Marine areas with legal protection

The fourth indicator provides information on marine areas with legal protection. To report on this indicator, the following are measured:

• the percentage of New Zealand’s territorial sea in marine reserves

• the percentage of each class of the Coastal Biogeographic Regions Classification protected by marine reserve.

Marine reserves

Marine reserves are fully protected areas established under the Marine Reserves Act 1971. Until a Marine Protected Area network is established (see box ‘Government action on protecting the marine environment’ later in this chapter), this indicator will report on marine reserves within the territorial sea. Wider marine protection mechanisms, including those in the EEZ, are not reported on using this indicator.

Department of Conservation records are used to report on the size and location of marine reserves in New Zealand’s territorial sea. By comparing this information with the Coastal Biogeographic Regions Classification (which divides New Zealand’s territorial sea into 13 regions), we can show the percentage of each class of coastal biogeographic region protected by a marine reserve.

Milford Sound Marine Reserve – one of a number of marine reserves in New Zealand.

 

Source: Courtesy of the Department of Conservation.

Threatened marine species

Information on the state of New Zealand’s threatened marine species is included in this chapter to present a more rounded picture of our oceans. This includes information about:

• marine species on New Zealand Threat Classification lists

• migratory marine mammals and seabirds on the International Union for the Conservation of Nature and Natural Resources (IUCN) Red List of Threatened Species.

New Zealand Threat Classification lists

The New Zealand Threat Classification lists classify all threatened and potentially threatened species that breed in New Zealand waters.

The classification uses information on population size, the range of the species, and population trends to determine the level of threat.

The classification system groups threatened species into the following three categories:

• acutely threatened: nationally critical, nationally endangered, or nationally vulnerable

• chronically threatened: in serious decline or gradual decline

• at risk: sparse or range-restricted.

International Union for the Conservation of Nature and Natural Resources Red List of Threatened Species

The IUCN Red List classifies threatened and potentially threatened species across the world. This chapter focuses on the species of marine mammals and seabirds on the IUCN Red List that migrate through New Zealand waters.

The IUCN Red List groups threatened species into the three categories of:

• critically endangered: considered to be facing an extremely high risk of extinction in the wild

• endangered: considered to be facing a very high risk of extinction in the wild

• vulnerable: considered to be facing a high risk of extinction in the wild.

Limitations of the indicators

The limitations of the indicators for oceans are explained below.

The two fisheries indicators do not measure:

• the environmental effects of fishing and trawling on marine ecosystems

• the effects from fishing activities on fish species that are not within the quota management system.

The recreational water quality indicator measures the water quality only at monitored beach sites, which may or may not be representative of recreational water quality elsewhere in New Zealand. In addition, beaches are often monitored only when there is a known problem with water quality.

The marine protection indicator does not measure how effective marine reserves are at protecting threatened marine species.