Research casts off poo fears about Huon Yellowtail Kingfish sea pens at Port Stephens

Fears the Huon Yellowtail Kingfish aquaculture program under trial off Hawks Nest might cause a build up of fish castings on the ocean floor have failed to pan out.

The University of Newcastle has conducted independent analysis of nutrient levels and invertebrates – key indicators of sea health – beneath the ocean pens since the trial was established a year ago. Dr Troy Gaston and Dr Margaret Platell have overseen the analysis of the samples both beneath the pens and in the wider area, 40 metres down.

Dr Platell is a marine scientist with a specialty in the food webs of fish species and the invertebrates they feed on.

“I cannot see any cause for concern. Because it’s in open water it’s quite different to the Tasmanian program in harbour environments,” she said.

“[To stop it] I can’t see any reason whatsoever.”

The NSW Department of Primary Industries invited UoN to oversee the trial.

Specifically, any nutrient loads put on the environment. Sandy substrate samples were collected before the trial began to establish a benchmark of the living organisms in this material. Based on the established science the number of those organisms is known to increase where there is higher nutrient level.

“There looks like there is a slight enhancement and small increase in the number of invertebrates. We didn’t know what to expect [but] these are only minor effects,” she said.

A series of samples has since been taken from a variety of sites. One immediately below the pens, as well as within the general lease area and outside the lease.

Each sample is two-to-four litres and the contents are passed through a sieve, to identfy and count the invertebrates under a microscope.

Video footage also shows some juvenile flathead on the coarse-sand ocean floor.

“Huon has been open and accommodating of our requests for research,” Dr Platell said.

“Huon even agreed that there should be an additional [monitoring] site to the south of the lease.”

Huon Aquaculture bought the Marine Aquaculture Research Lease in Providence Bay off the failed Pisces fish farm in 2014.

Huon hopes to establish itself as a sustainable supplier of yellowtail kingfish in a similar means to its Atlantic salmon production in Tasmania.

Dr Platell said her associated research would help inform future farms.

“I know there has been community concerns, I completely understand that,” she said.

“But when you look at the demand for seafood its a matter of weighing up the environmental impacts, whether its traditional fishing or fish farming. The environment needs to be able to sustain any fishing or aquaculture activity.”

The results of these surveys and footage of the sea floor beneath the MARL is available at huonaqua.com.au

Source: http://www.portstephensexaminer.com.au/story/4962208/research-debunks-build-up-of-manure-under-fish-farm-pens/

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