Home sweet home: identifying prime real estate for deep-water fish

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Curtin University researchers have collaborated on a project which could pave the way for the long-term sustainable management of deep-water fish and their habitat across the Indian and Pacific oceans.

Researchers used predictive species distribution modelling to accurately map the distribution of commercially valuable Hawaiian bottomfish, a fishery which targets a group of deep-water species including snappers, groupers and jacks. These species are distributed, and fished commercially, across the Indo-Pacific including Australia.

The findings identified ‘core’ bottomfish habitat, where all species co-exist, which will allow fishing regulatory bodies to identify the most important areas for management.

The study’s lead author, Dr Cordelia Moore, Curtin’s Department of Environment and Agriculture, said ecosystem-based, or place-based, fisheries management is a new method being adopted globally, and provides a more holistic approach to managing and protecting our marine resources for the long-term.

“Currently there is a lack of detailed information on the spatial distribution of many marine species and the environmental conditions that shape them. This is particularly problematic for deep-water species that are hard to sample, meaning there is less data available to manage their populations,” Dr Moore said.

The study results showed each species responded to a unique combination of environmental conditions, with little overlap, suggesting that effective management of deep-water fisheries must take into account species-specific differences.

Dr Moore said the findings could support the sustainable management of the Hawaiian bottomfish fishery, and provide details for the future management of deep-water fish and their habitats in other parts of the world.

“Most of the species are long lived and can live up to 40 years, which means they have longer to successfully reproduce and maintain a healthy population,” Dr Moore said.

“This makes these populations particularly vulnerable to overfishing and in need of careful management,” Dr Moore said.

The research paper, titled Improving essential fish habitat designation to support sustainable ecosystem-based fisheries management, was published this month in the journal Marine Policy.

The project was a collaboration between Curtin University, the University of Hawaii Deep Sea Fish Ecology Lab, the Australian Institute of Marine Science and the Department of Land and Natural Resources Division of Aquatic Resources via the Sportfish Restoration program.

Can we rely on satellite data to monitor the Kimberley Marine Park?

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Scientists from Curtin University and CSIRO have been investigating how data collected from satellites can help to provide the information needed to monitor the extensive waters of the Kimberley Marine Park.

The Kimberley region is vast and remote, making it difficult and expensive to access and monitor, but satellite remote sensing technologies are providing a cost effective method to gather historical and baseline data with broad spatial coverage and high repeat frequency at metre to kilometre scales of resolution.

A Western Australian Marine Science Institution project has focused on measurements of the turbidity of marine waters using NASA’s MODIS sensor on its Aqua satellite. 

“The murkiness or turbidity of waters directly impacts the amount of light reaching the seabed, so plays an important role in determining what organisms can exist and grow in these environments,” CSIRO’s Dr Nick Hardman-Mountford said.

 

To confidently monitor turbidity through time and quantify how it changes seasonally and between years, it is necessary to know the precision of the satellite-derived measurements. However, as with any derived data, there are uncertainties about how accurate a picture remotely sensing can provide and at what scale. These have not been determined previously for Kimberley waters.

To help remedy this, a key component of the research has been to analyse these uncertainties for remotely sensed turbidity ‘products’ by making comparisons with archived “in water” measurements, and by looking at what resolutions work best.

In situ data was obtained from a number of recent expeditions that occurred along the Kimberley and Pilbara coastline including sites in King Sound, Collier Bay, in the vicinity of King George River, and near Onslow on the Northwest Shelf. Data being used by the team includes specialised optical measurements, as well as measures of turbidity and vertical light attenuation.

The project is due to be completed in December 2016.
 Landsat image pan-sharpened to 15 m resolution. The town of Derby is clearly visible, as well as extensive mudflats exposed at low tide.

 

The $30 million Kimberley Marine Research Program is funded through major investment supported by $12 million from the Western Australian government’s Kimberley Science and Conservation Strategy co-invested by the WAMSI partners and supported by the Traditional Owners of the Kimberley.

Category: 

Kimberley Marine Research Program

Whales from space

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By: Cassidy Newland (AIMS)

It’s as strange as it sounds… researchers are looking for whales in the Kimberley from a vantage point of 770 kilometres above sea level using the Worldview 2 Satellite.

The Satellite captures a spatial resolution of 0.46 metre pixels in the Panchromatic band and a spatial resolution of 1.6 metre pixels in the 8 band Multispectral image (Figure 1).

 

The Panchromatic band captures light across the visible spectrum in a single band and is often displayed as a grey scale image. It has a higher spatial resolution of up to 0.46m, but a lower spectral resolution than the multispectral. The multispectral has 8 bands extending from the far blue through the visible spectrum to the near infra-red providing higher spectral resolution but the spatial resolution is only up to 1.6m.

A number of surveys by different organisations had previously been carried out in the Kimberley by plane, boat and some from land and for the first stage I looked for an image in the World view 2 archive to match one of these.

Although there is a large archive of imagery since the satellite commenced operation in 2009, matching an exact date was difficult and we were lucky to find several images matching surveys conducted in August 2010. I acquired one image which I expected would have the most whales and began the task of looking for them.

At 12-16 metres long you might expect a Humpback whale to be relatively easy to distinguish, but in the multispectral image with 1.6m pixels, a whale seen fully surfaced will only be up to 10 pixels long. Figure 2 shows a simulation based on an actual aerial photo of what a whale might look like in a satellite image.

 

In actuality only a single fully surfaced whale was distinguishable, but with a lot of interpretation and a little imagination a range of whale related features were identified including partially surfaced whales, submerged whales, the foot print of recently surfaced whales, bubble rings from below and even what appears to be a bubble net.

These features are examined in each band to see where they can be best distinguished and determine what band or combination of bands will be used in the analysis to identify further features. There is also testing of the similarity of features within a type and testing of separability of each type. The result is a refined set of features which can then be used to train and verify success of the remote sensing techniques used.

The techniques used included thresholding where cut-off values are defined manually, supervised classifications using the features as training sites and unsupervised classifications where clusters are identified statistically. Of these, thresholding and unsupervised classification provided the best results.

Challenges were noise from shallow water, swell and turbidity, but it was possible to identify surfaced whales, whale footprints, some submerged whales and boats.

 

Related Links:

WAMSI Project 1.2.1 Humpback Whale Distribution project

ABC Kimberley’s Erin Parke talks to WAMSI/AIMS researcher Michele Thums about satellite tagging humpback whales:

The $30 million Kimberley Marine Research Program is funded through major investment supported by $12 million from the Western Australian government’s Kimberley Science and Conservation Strategy co-invested by the WAMSI partners and supported by the Traditional Owners of the Kimberley.

Category:

Kimberley Marine Research Program

Broome boat ramp study indicates boating popularity

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Researchers have analysed a year’s worth of video imagery from the popular Entrance Point boat ramp, adjacent to the Broome Fishing Club, to explore the factors affecting the launching of recreational boats, as part of a broader WAMSI study looking at Human Use in the Kimberley.

In total, 6057 recreational boat launches were recorded by the Western Australian Department of Fisheries camera at Entrance Point during the 12 month study. The figure shows that, despite the town of Broome only having a relatively small resident population of about 13,000 people, boating is a popular activity.

To put it into context, the total at Entrance Point is equivalent to about 22 per cent of the total number of launches per year at Hillarys boat ramp which is one of the busiest in the Perth Metropolitan area.

On a seasonal basis, 60 per cent of all boat launches at Entrance Point occurred during the dry, winter season (May to October) and on a monthly basis, July and August had the highest numbers of boat launches (totals of 825 and 882, respectively).

The average number of boat launches per day generally showed an increase on weekends although from July to September there were increased numbers of launches on weekdays as well.

Throughout the year, the peak in boat launching took place in the morning between 6 am and 10 am.

Mean hourly boat launch rate per month at Entrance Point boat ramp, Broome, from November 2012 to October 2013.

“The results support the original hypothesis that there would be an increase in boat launches during the dry, winter season when there are known to be more visitors (especially ‘grey nomads’) to Broome,” project leader Murdoch University’s Professor Lynnath Beckley said. “However, consistent launching of boats during the wet, summer season (40 per cent of all launches) clearly indicates the importance the residents of Broome place on recreational boating.”

The boat launching data were also explored relative to environmental factors like air and sea temperature, wind speed and direction, rainfall, barometric pressure and tides as well as time of day, day type (weekday, weekend or public holiday) and school holidays.

Time series analyses of the hourly launch data showed that day type, time of day, school holidays and tidal height were significant predictors that together described the most variation in the launches on a daily cycle.  For the weekly cycle, only day type and wind speed were significant predictors.

“The Entrance Point boat ramp is only one of several sites from where recreational boats are launched in Broome and this may have some bearing on the patterns found,” Professor Beckley said. “For example, during the winter mornings when there can be strong easterly winds, many boats are launched instead from the southern end of Cable Beach which is more protected from these winds.”

Entrance Point boat ramp at Broome in peak season (Lynnath Beckley)

The $30 million Kimberley Marine Research Program is funded through major investment supported by $12 million from the Western Australian government’s Kimberley Science and Conservation Strategy co-invested by the WAMSI partners and supported by the Traditional Owners of the Kimberley.

Category:

Kimberley Marine Research Program

Broome boat ramp study indicates boating popularity

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Researchers have analysed a year’s worth of video imagery from the popular Entrance Point boat ramp, adjacent to the Broome Fishing Club, to explore the factors affecting the launching of recreational boats, as part of a broader WAMSI study looking at Human Use in the Kimberley.  

In total, 6057 recreational boat launches were recorded by the Western Australian Department of Fisheries camera at Entrance Point during the 12 month study. The figure shows that, despite the town of Broome only having a relatively small resident population of about 13,000 people, boating is a popular activity.

To put it into context, the total at Entrance Point is equivalent to about 22 per cent of the total number of launches per year at Hillarys boat ramp which is one of the busiest in the Perth Metropolitan area.

On a seasonal basis, 60 per cent of all boat launches at Entrance Point occurred during the dry, winter season (May to October) and on a monthly basis, July and August had the highest numbers of boat launches (totals of 825 and 882, respectively).

The average number of boat launches per day generally showed an increase on weekends although from July to September there were increased numbers of launches on weekdays as well.

Throughout the year, the peak in boat launching took place in the morning between 6 am and 10 am.
 

Mean hourly boat launch rate per month at Entrance Point boat ramp, Broome, from November 2012 to October 2013.

“The results support the original hypothesis that there would be an increase in boat launches during the dry, winter season when there are known to be more visitors (especially ‘grey nomads’) to Broome,” project leader Murdoch University’s Professor Lynnath Beckley said. “However, consistent launching of boats during the wet, summer season (40 per cent of all launches) clearly indicates the importance the residents of Broome place on recreational boating.”

The boat launching data were also explored relative to environmental factors like air and sea temperature, wind speed and direction, rainfall, barometric pressure and tides as well as time of day, day type (weekday, weekend or public holiday) and school holidays.

Time series analyses of the hourly launch data showed that day type, time of day, school holidays and tidal height were significant predictors that together described the most variation in the launches on a daily cycle.  For the weekly cycle, only day type and wind speed were significant predictors.

“The Entrance Point boat ramp is only one of several sites from where recreational boats are launched in Broome and this may have some bearing on the patterns found,” Professor Beckley said. “For example, during the winter mornings when there can be strong easterly winds, many boats are launched instead from the southern end of Cable Beach which is more protected from these winds.”

Entrance Point boat ramp at Broome in peak season (Lynnath Beckley)

 

The $30 million Kimberley Marine Research Program is funded through major investment supported by $12 million from the Western Australian government’s Kimberley Science and Conservation Strategy co-invested by the WAMSI partners and supported by the Traditional Owners of the Kimberley.

Category: 

Kimberley Marine Research Program

IMOS to drive fresh future for marine priorities in the west

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WAMSI welcomed the Commonwealth’s announcement that provides funding certainty for the National Collaborative Research Infrastructure (NCRIS) program. The NCRIS created and developed the Integrated Marine Observing System (IMOS) and the $1.5 billion commitment over the next decade gives IMOS a guaranteed share, and a green light to make plans for the future.

Associate Professor Julian Partridge is the new Western Australian IMOS (WAIMOS) node leader, responsible for advising the national program on regional priorities and directions for investment.

Associate Professor Julian Partridge, CEO WA-IMOS

With the launch last year of Western Australia’s Blueprint for Marine Science priorities, backed by the National Marine Science Plan, WAIMOS has strong benchmarks to draw on to drive the State’s marine observing priorities, including strongly advocated research collaborations and data sharing.   

“A focus for the coming months will include the review of priorities for deployment off the western coast of Australia,” Associate Professor Partridge said. “With the welcome new lease of life from the NCRIS decisions, we have the chance to take stock and make sure we’re measuring the most important things. In addition, we need to maximize the value of WAIMOS data to a variety of stakeholders and end users; and we need to consider our activities in the light of both impact and innovation agendas.”

IMOS has produced data that has enabled the development of a wide range of regional models that improve the understanding of both local and distant ocean currents and processes, which have supported both private and public management and policy decisions.

WAMSI will continue to support the WAIMOS node and take steps to connect it into the continuing Blueprint process to improve the input from industry, government and consultants to the framework and priorities for IMOS.

“We have a relatively short timeline to develop priorities for the next five years of IMOS investment,” WAMSI CEO Patrick Seares said. “However, we are fortunate in Western Australia that we have both worlds: an end-user led Blueprint for Marine Science 2050 report explicitly outlining industry and government priorities for new information; and a National Marine Science Plan containing expert and in-depth analysis of what research and capability is required. These processes plus the more recent Forum for Operational Oceanography allow us to ensure we are advising IMOS to invest in the most valuable observations off our coast, safe in the knowledge we’re meeting the priorities for both research and end-users.”

That sinking feeling: Suspended sediments can prevent the ascent of coral egg bundles

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New research has demonstrated a previously unrecognised event that can markedly reduce the probability that coral gametes (egg-sperm bundels) reach the water surface and come in contact with each other.

Inshore reefs are regularly exposed to higher concentrations of suspended sediments during storms, runoff and dredging. While it has been recognised that suspended sediments can negatively impact fertilisation and later life cycle stages, the vulnerability of the egg-sperm bundles during their journey to the water’s surface has not been considered.

Lead author of the WAMSI research published in Scientific Reports Gerard Ricardo (AIMS/UWA) explained many corals reproduce through synchronised broadcast spawning of gametes and the buoyancy of egg-sperm bundles is critical to fertilisation at the ocean surface.

“We demonstrated that during their ascent to the surface, the egg-sperm bundles can run into suspended sediment grains that stick to their mucous coating, and that under certain water quality conditions the sediment grains are enough to cause a significant number of bundles to sink and never reach the water surface, or be slowed in their ascent” Gerard said.

A coral colony releases egg-sperm bundles into the water column. (G. Ricardo)

The detrimental effect this has on the reproduction of corals is made worse by the fact that the bundles carry both eggs and sperm and the bundles need to reach the water surface and break apart for fertilisation to occur. So if less bundles make it to the surface, the coral spawn slick will be less concentrated and therefore there is less chance two compatible gametes will bump into each other.

“Even if the egg-sperm bundles do make it to the surface, they may arrive too late and miss the party; as wind, waves and currents can quickly dilute and disperse a coral spawn slick,” Gerard explained.

Microscopy image of a coral egg-sperm bundle after failed ascent through elevated concentrations of suspended sediments, revealing considerable attachment of sediment grains (yellow) to the bundles (purple). (Gerard Ricardo)

The observations were captured using a mathematical model that predicts the reduction in ascent probability and egg-sperm encounters as a function of sediment load, depth and particle grain size.

For reefs at 15 metres deep, the model predicts that a coarse silt could reduce 10 per cent of egg-sperm encounters at suspended sediment concentrations of 35 milligrams per litre, and for a reef at 5 metres deep, it could reduce 10% of the encounters at 105 milligrams per litre.

“This is the first study to examine the effects of environmental pressures on the success of coral gamete ascent, which can have important flow-on effects for the ability of a reef to maintain and recover its population,” Gerard said. “It adds to the list of stressors impacting early life history stages of corals and could prevent new corals from adding to the population on nearby reefs.”

It’s thought the mechanism and model used in this research could also be used to determine the effects of sediment grains on the reproductive success of other marine organisms that rely on positively buoyant eggs for fertilisation including some echinoderms, molluscs and fish.

Gerard Ricardo and researchers in the lab A microscopy image of an egg-sperm bundle showing eggs (orange) and sperm (white). (G. Ricardo)

Related Links:

The WAMSI Dredging Science Node is made possible through $9.5 million invested by Woodside, Chevron and BHP as environmental offsets. A further $9.5 million has been co-invested by the WAMSI Joint Venture partners, adding significantly more value to this initial industry investment. The node is also supported through critical data provided by Chevron, Woodside and Rio Tinto Iron Ore.

Category: 

Dredging Science