Marine Data - Page 8

Heavy metals occur naturally in estuaries, but high concentrations suggest contamination from another source. The metals can be transported along waterways from urban environments (and, for cadmium, from farmland) and accumulate in estuarine and coastal sediments. They are toxic and accumulate in fish and shellfish. We focus on four heavy metals: lead, copper, zinc, and cadmium.
This dataset relates to the "Heavy metal load in sediment" measure on the Environmental Indicators, Te taiao Aotearoa website.

The Hector’s and Māui’s dolphins are subspecies of the small dolphin Cephalorhynchus hectori. They are endemic to New Zealand (not found anywhere else). The Hector’s dolphin is classified as nationally endangered, while the Māui’s dolphin is nationally critical. Reporting incidental dolphin deaths from fishing helps us understand the pressures our protected marine species face from fishing.
This dataset relates to the "Bycatch of protected species: Hector’s and Māui’s dolphin" measure on the Environmental Indicators, Te taiao Aotearoa website.

New Zealand waters have at least 113 species of chondrichthyans (sharks, rays, and other cartilaginous fish species). They are particularly vulnerable to overfishing because they are long-lived, mature slowly, and have a low reproductive rate. Chondrichthyans are important for healthy ocean ecosystems, and reporting their commercial catch and bycatch helps us understand the sustainability of our fisheries.
This dataset relates to the "Commercial catch: sharks and rays" measure on the Environmental Indicators, Te taiao Aotearoa website.

Extreme wave indexes estimate the occurrence of extreme wave events in coastal and oceanic waters. Extreme wave indexes estimate the number of times a significant wave height exceeds one of three threshold values for at least 12 hours in 24 marine regions. The three wave-height thresholds are four metres, six metres, and eight metres.
This indicator estimates the exceedances of wave-height thresholds for each year from 2008 to 2015 in oceanic areas around New Zealand.
Significant wave height is a measure of the ‘typical’ wave height in a place over a time period. It is four times the standard deviation of the water surface if, for example, you were to measure water moving up and down a jetty piling for an hour. The largest individual wave will typically have a height around twice the significant wave height.
We use three wave-height thresholds because of the regional variation in extreme wave events. In general, the north experiences less exposure to consistently strong winds, and the waves generated by them, than the south. Four-metre tall waves are considered extreme in the northern-most parts of New Zealand but are more common in the south. For the southern-most parts of New Zealand, eight-metre waves better represent extreme wave events.

New Zealand waters have at least 113 species of chondrichthyans (sharks, rays, and other cartilaginous fish species). They are particularly vulnerable to overfishing because they are long-lived, mature slowly, and have a low reproductive rate. Chondrichthyans are important for healthy ocean ecosystems, and reporting their commercial catch and bycatch helps us understand the sustainability of our fisheries.
This dataset relates to the "Commercial catch: sharks and rays" measure on the Environmental Indicators, Te taiao Aotearoa website.

Marine mammals, seabirds, and shorebirds are indicator species for the state of our marine environment. A decreasing population can indicate that the ecosystem is degrading. New Zealand has a diverse range of marine species, many of which are endemic to (only breed in) New Zealand. They are apex species (near the top of the food chain) and can thrive only if their ecosystems are healthy.
This measure reports on the number of indigenous marine species that have had a genuine change in conservation status between two monitoring periods (2008–11 and 2012–14). A change in a species’ conservation status reflects a change in its risk of extinction.

Marine non-indigenous (exotic) species arrive in New Zealand waters on the hulls of international vessels (biofouling) or in discharged ballast waters. Some have little impact or cannot survive in New Zealand waters; others have a negative impact on our native habitats and species and become pests. They can compete with, and prey on, indigenous species, modify natural habitats, affect marine industries or can alter ecosystem processes. The potential impact of non-indigenous species on our native habitats and species means they could threaten our cultural and natural heritage, as well as economic activities such as commercial and recreational fishing, shellfish harvesting, and aquaculture.

Seabed trawling and dredging, when fishing nets or dredges are towed near and along the seabed, can physically damage seabed (benthic) habitats and species. It can also stir up sediment from the seabed, shading (in shallow waters) or smothering marine species. This measure focuses on coastal areas (waters shallower than 250m). Focusing on coastal benthic habitats is important as these face multiple threats (for example, from land-based activities) in addition to fishing

Marine non-indigenous (exotic) species arrive in New Zealand waters on the hulls of international vessels (biofouling) or in discharged ballast waters. Some have little impact or cannot survive in New Zealand waters; others have a negative impact on our native habitats and species and become pests. They can compete with, and prey on, indigenous species, modify natural habitats, affect marine industries or can alter ecosystem processes. The potential impact of non-indigenous species on our native habitats and species means they could threaten our cultural and natural heritage, as well as economic activities such as commercial and recreational fishing, shellfish harvesting, and aquaculture.

Along with sea lions, fur seals, and dolphins, seabirds are the protected species most directly affected by fisheries in New Zealand waters. Estimating seabird deaths from bycatch is one way of assessing the pressure some seabird species face from current fishing practices.
This dataset relates to the "Bycatch of protected species: seabirds" measure on the Environmental Indicators, Te taiao Aotearoa website.