In search of fish food on the Chatham Rise

NIWA's research vessel Tangaroa will set sail for the Chatham Rise tonight to improve our understanding of how marine ecosystems affect commercially exploited fish, and how commercial fisheries affect the marine food-web. The Chatham Rise, a large plateau between the South Island and Chatham Islands, is our most productive fishing ground.

A better understanding of the interactions between commercially exploited fish species and the rest of the marine ecosystem helps with the sustainable management of our fisheries. The Chatham Rise fisheries have huge economic significance to New Zealand.

An important part of the study involves looking at protected areas of the Chatham Rise, as well as areas that might be licensed for mineral exploration and extraction.

"The research voyage aims to measure the abundance of the species that fish like Hoki, Ling, Orange Roughy and Oreos eat," says NIWA project leader Dr Matt Pinkerton. "And what these prey species eat in turn."

NIWA's voyage leader, Dr Scott Nodder says, "We are looking at the prey of the main commercial fish species on the Chatham Rise and at how they are linked to other parts of the food web. We are trying to sample from bacteria right up to fish, to give us a better understanding of how the prey of fish fit into the entire ecosystem, to enable better management of ocean resources."

A range of different sampling and surveying equipment will be used, some during the day and some only at night, depending on which types of species are being targeted. Sampling and surveying will be done at various depths, right down to samples of the sea floor. The scientists plan to use acoustic surveying, trawling with very fine nets (for small fish and plankton), a benthic sled, a sediment corer, and various water samplers.

The trip will take 21 days. Scientists from NIWA will be accompanied by researchers from Australia, Canada, and New Zealand universities.

This is the second voyage in a series investigating the Chatham Rise ecosystem. This survey is funded by the Ministry of Science and Innovation.