Category Archives: Environment

Why is the East Australian Current Behaving so Badly?

18th October 2016

The East Australian Current (EAC) is a flow of water that is formed from the South Equatorial Current crossing the Coral Sea and reaching the eastern coast of Australia off Queensland. As the South Equatorial Current hits the Australian coast it divides forming the southward flow of the EAC. eacThe EAC is the largest ocean current close to the shores of Australia reaching a maximum velocity at about Coffs Harbour in NSW where its flow can reach a speed of 3 km per hour.

In the animated film Finding Nemo Marlin and Dory use the EAC as a superhighway travelling with fish and sea turtles to Sydney Harbour. The EAC is dominated by eddies which are circular currents of water that form whirlpools of up to 100km in diameter.

Their swirling motion is one of the forces that make nutrients found in cold, deep waters to come up to the surface of the ocean where phytoplankton (microscopic plants) feed on them.

Eddies do occur off the coast of Tasmania but a change in their behaviour over the last 24 years is concerning. These eddies are generated in the EAC and most of them do not go south of Bass Strait. When they do, they bring warm water with them and the bigger they are the more heat they can bring.

eke_fig_final

Scientists have noted a trend in eddies off Tasmania becoming larger, stronger and more frequent. Following the 1990s, eddy kinetic energy (EKE) increased gradually both north (red line in graph below) and south (blue line in graph below) of Bass Strait,  with a huge spike in eddy activity  off Tasmania (8 times the average EKE of the 1990s) in 2014 (see animation below). This trend is in agreement with climate modelling but there has been a dramatic increase over the last couple of years.

The presence of eddies south of Bass Strait is believed to be responsible for the atypically warm sea surface temperatures experienced off the east coast of Tasmania in 2015. If the eddy encountered off north east Tasmania in July this year is anything to go by (see image below), this heating trend is expected to continue into 2016.

A team of CSIRO scientists, AFMA observer and commercial fishermen from the South East Trawl Fishery came upon the eddy while conducting acoustic surveys of orange roughy off the north east coast of Tasmania in July 2016 as part of an ongoing monitoring program. eacIt was fast and hot and gave the team a bit of a hard time by making the deployment and retrieval of their sampling gear very challenging.

The eddy had current speeds of more than 2 knots and temperatures at its centre were more than 2 degrees warmer than the year round average between 100-400m depth and almost 1 degree warmer at 1200m depth. The eddy’s outer edge was close to the continental slope.

The implications of increased eddy activity on adult orange roughy spawning, orange roughy larvae, aquaculture, other fisheries and Tasmanian coastal waters in general are unknown. However, hot eddies warm up all the water around them and the bigger they are the deeper and wider their impact so if this trend continues there is no doubt that the Tasmanian offshore environment will change – the ‘how’ is anyone’s guess!

For up to date ocean information around Australia visit the IMOS Ocean Current website.

 

Marine Mammal Report Released

18th October 2016

All primary production has environmental impacts and most have some impact on native mammal populations.  On land, farmers can apply for permits to destroy kangaroos while no rules exist for vehicle road kill.  However, in the marine environment the rules are much tougher.  All marine mammals are afforded protection under the Environmental Protection and Biodiversity Conservation Act which requires that all reasonable steps be taken to reduce interactions.  Fishery by-catch is considered within the Fisheries Management Act.

AFMA already run a process called an Ecological Risk Assessment (ERA) that considers the effects of commercial fishing on all species including marine mammals.  The ERA is a tiered hierarchical framework that assigns species a low, medium or high risk so management actions can be prioritised.  Management actions are tracked in each fishery’s by-catch and discard work plan.

Rules are already in place to protect Australian sea lions in the Gillnet, Hook and Trap Fishery (GHAT).  Trigger limits have been set considering population structure and the number and location of breeding colonies.

Dolphin interactions sometimes occur in the Small Pelagic Fishery (SPF) and GHAT Fisheries and AFMA have implemented spatial management measures aimed to reduce the impact on dolphins.  If an accidental dolphin mortality occurs in the SPF a vessel cannot return to one of seven management zones for six months.  Similar rules exist in the GHAT.  The precautionary principle states that if effects are unknown that management should be very conservative and to some extent this is why the limits on dolphins are so low.  The method by which trigger limits for dolphins in particular are set have been questioned and the FRDC have released a report that aims to increase knowledge that can be used to set sensible limits for dolphins but also for other marine mammals.

The FRDC report calculates something called Potential Biological Removals (PBR) for several groups of marine mammals.  PBR is the maximum number of animals, not including natural mortalities, that can be removed from a marine mammal stock while allowing that stock to reach or maintain its optimum sustainable population.  In no way is it a target or quota.  PBR is widely used in the US where fisheries are classed as “strategic” if they cause mortality greater than 50% of the PBR and “non-strategic” if it is less than 50%.  Management measures are prioritised accordingly.

Thankfully, the trawl sector does not have sea lion interactions and dolphin interactions are very rare (less than one per year) so the Association’s marine mammal focus is on both species of fur seals; Australian and New Zealand.

Using the lowest population estimate available of 87,000 seals the Australian fur seal PBR, or safe level of removal, is 2,623 to 4,721 individuals per annum.  One third of fur seal interactions in the trawl fishery result in the seal being released and swimming away.  The PBR calculation uses conservative population modelling estimates, the lowest estimate of stocks and does not consider the population of New Zealand fur seals – all of which make the PBR lower than it is likely in reality.  Even with this level of precaution built into the numbers the PBR is thousands more than the trawl industry take.  This outcome would make the trawl fishery classed as “non-strategic” or low priority in the US context.

The Association welcomes the report but continues to be committed to taking reasonable steps to reduce our environmental impacts.  A long term project that aimed to reduce seal interactions by shortening trawl nets was unsuccessful.  Growing seal populations make reducing interactions difficult.  SETFIA members operate under a code of conduct that has reduced seal interactions and this code continues to be taught in training run by the Association.   Training programs have already significantly increased our sector’s non-observed reporting of seals and are ongoing.

The report’s focus was mammals so did not consider seabirds but the Association’s target of reducing seabird interactions (versus bare warps) by more than 90% by May 2017 remains on track.

Searching for school shark pups in South Australia

20th July 2016

Matt McMillan is a PhD candidate working on school shark (Galeorhinus galeus) at the University of Adelaide. He needs your help to find school shark pupping grounds that may exist in South Australian waters.

School shark numbers declined in the 1990s and conservative total allowable catches (TACs) have been set to help them recover. School shark are no longer targeted by commercial fishers and are only caught incidentally while targeting gummy shark and other species. Anecdotal evidence suggests that school shark numbers are on the increase and their abundance is currently underestimated. However, before TACs can be raised science must support and increase in the school shark stock.

School shark are ovoviviparous meaning that they lay eggs which are hatched within the body of the parent. A lot of research has been done on the pupping grounds in Victoria and Tasmania but calculations have shown that the number of pups produced in these sites are too low to sustain the whole stock.

Matt’s hypothesis is that school shark may also be pupping in South Australia, and not just in Tasmania and Victoria. To test this theory, Matt plans to deploy underwater cameras at locations that school shark may use as nursery areas. He is calling on commercial fishers with knowledge and experience about school shark movements and behaviours to help him find locations in South Australia where sub 40 cm school shark have been caught.

Matt’s work will help address an important knowledge gap that the Commonwealth school shark stock rebuilding strategy (2008) acknowledges. Doing so could have strong benefits for the management of school shark.

If you have any information about school shark pupping grounds in South Australian waters or know someone who does call Matt on 0405-024344 or matthew.mcmillan@adelaide.edu.au .

Fishermen call for use of new technology to reduce effects on seabirds

30th June 2016

The South East Trawl Fishing Industry Association and the Great Australian Bight Fishing Industry Association (GABIA) have developed world leading technology that reduces interactions between trawlers and seabirds by up to 96%. Plans are in place to roll this technology out across the trawl fleet.

Trawl fishermen from both Commonwealth managed trawl fisheries in South Australia are committed to minimising our environmental impact while catching fresh locally sourced fish for all Australians.  This includes reducing our impacts on seabirds like albatrosses.  Seabirds are attracted to our fishing operations by the sight and smell of fish and sometimes they interact with the steel cables (warps) used to tow trawls.  An interaction is any contact between a fishing vessel and a seabird that causes deviation to its path, distress, injury or death.

In 2010 the trawl industry supported a management rule which saw all trawl vessels use pinkies – large brightly coloured inflatable boys that physically push seabirds to the sides of the two warps where they enter the water.  Pinkies have proven to reduce seabird warp strikes by around 75% compared to unprotected warps with no mitigation device.  However, pinkies can become tangled in fishing gear and we believed we could do better to further reduce interactions with seabirds.

In 2014 we received an Australian Government grant of $360,000.  A steering committee of trawl fishermen from the Great Australian Bight and South East Australia, the Australian Fisheries Management Authority (AFMA), the Australian Antarctic Division, Fishwell Consulting and the CSIRO oversaw a project during which a delegation travelled to New Zealand, (where the seabird issue is more significant), to identify and adapt seabird mitigation devices that might work in Australia.  The team returned, built and fine-tuned two new devices, designed a scientific testing program and then used independent sea-going observers to complete a study on their efficacy.

A device called a sprayer sprays seawater on the area where the warp enters the water.  Seabirds hate being sprayed so keep away from warps.  The sprayer is now proven to reduce interactions by 90%.

A second device called a bird baffler creates a long curtain of ropes and pieces of plastic piping which acts as a fence to prevent seabirds from entering the danger zone near the warps.  The trial has shown that bird bafflers reduce interactions by 96%.

AFMA have now approved both devices for seabird mitigation.

SETFIA and GABIA have taken the further step of calling on AFMA to mandate that all vessels must use one of the following three seabird mitigation strategies by April 30, 2017

  1. Sprayers
  2. Bird bafflers
  3. Pinkies and stringent offal management rules  sufficient to remove the attractiveness of the vessel to seabirds

AFMA have agreed and have written to trawl operators advising them of these new rules.  From May 2017 (the new fishing season) all seabirds in the Southern Ocean will be protected from Commonwealth managed trawlers’ warps by one of these strategies.

We thank the members of the project’s steering committee; the seagoing observer, the owners and crew of the trial vessels; the Imlay and the Lady Miriam, and finally the Australian Government for their generosity in supporting our commitment to saving seabirds.

[Image of Southern Bullers Albatross copyright Tamar Wells.]

Gulper exclusion trial successful

10th December 2015

The gulper exclusion proof-of-concept trial has been successful. Read on to learn more and see trawl footage taken at 500m depth.

Harrisson’s dogfish and southern dogfish are part of a group of sharks called Upper-Slope Dogfish or Gulper Sharks. To rebuild populations of gulpers AFMA has put a series of closures in place.  These closures are equivalent in area to about 25% of total dogfish habitat available in the fishery.  Many of these closures overlap with grounds where royal red prawns are caught in the South East Trawl Fishery off Sydney.

In early 2014 SETFIA announced that it would trial a grid that aimed to catch royal red prawns but exclude gulpers.  The project team commissioned something they named a Gulper Exclusion Device or GED.  These are widely used in other Australian prawn fisheries.

New Picture (22)

A GED is an angled aluminium grid in the net that will deflect gulpers and other large fishes up and out of the net unharmed, while the smaller royal red prawns pass through to be caught (see image below). Underwater cameras were used to understand how gulper sharks and other larger fishes are ejected from the trawl net (see video above taken at 500m).

The footage clearly shows that the device works in that it ejects skates, small sharks and other fishes such as pink ling while allowing most prawns to pass through and be retained in the trawl’s codend.  Only four shots were completed and these were not in gulper habitat so none were encountered.

 

The Association and AFMA will now consider further research which aims to allow trawl fishing with a GED inside the Sydney gulper closure.

SETFIA thanked AFMA for funding the work, net-maker David Guillot who installed the GED, Wallace Hill the net maker and the Bagnato brothers who operate the survey vessel Francesca.

Final report on the project:

Final report RRP USD exclusion proof of concept

SETFIA and seabird conservation

21st October 2015

Seabirds are attracted to fishing vessels by the sight and smell of fish and fish offal.  At times seabirds have no interest in fishing vessels but at other times their behaviour becomes frenzied.  During these periods they can be injured or killed when they strike the steel cables (warps) used to tow trawl nets.

SETFIA members are committed to minimising their environmental impact while catching fresh fish for Australians.  This includes minimising interactions with seabirds.  An interaction is any contact between the vessel and a seabird that causes injury, death or distress.

As a condition on their fishing permit all trawlers in the South East Trawl Fishery must follow the directions of an approved Seabird Management Plan at all times. This plan directs each vessel to manage offal in a particular way and deploy an approved physical mitigation device when fishing in daylight hours.

SETFIA and the Australian Fisheries Management Authority have worked together to develop, trial and implement a range of physical devices which reduce interactions.  Three physical devices have been developed or are undergoing development:

Pinkies

Pinkies (originally called warp deflectors) large brightly coloured inflatable boys designed to physically push seabirds to either side of the area where the warp (enters the water.  Pinkies have been used by the majority of the fleet since 2010 and have proven to reduce seabird warp strikes by around 75% compared to bare warps with no mitigation device (source). See a video of the pinkies in action here

Australian Government Assistance

In 2014, SETFIA received an Australian Government ‘Caring for our Country’ grant of $350,000 to travel to New Zealand on a study tour and then develop and test devices and techniques to protect seabirds in the South East Trawl and Great Australian Bight Trawl Fisheries. Two devices have been developed and trialled – sprayers and bafflers.

Sprayers

Seabird sprayers create a curtain of moderate pressure water jets around the area where the warp enters the water. This device has proven very effective at reducing warp strikes and during our trial vessel returned a 92% per cent improvement over bare warps. Sprayers have now been approved by AFMA as an official mitigation method which is available for all trawl boats to use if they wish. See the sprayers in action here: Video 1 , Video 2

Bird Bafflers

The bird baffler creates a long curtain of ropes and pieces of plastic piping which acts as a fence to prevent seabirds from coming alongside the rear of the vessel where warp strikes may occur. So far this device has proved very effective, offering a 96% reduction in warp strikes compared to a bare warp. See the device baffling birds here and here. Note how the albatrosses can see the discarded fish on the inside of the fence, but can’t get through to grab them until they are well clear of the danger zone.  Bird Bafflers have now been approved by AFMA as an official mitigation method which is available for all trawl boats to use if they wish.

Resources:

FRDC Fish magazine seabirds

 

 

SETFIA, AFMA and the Australian Maritime College’s plan to save seals

15th April 2015

To address the issue of seal bycatch in trawl fisheries, SETFIA and AFMA are funding a fishing gear design competition open to all students of the Australian Maritime College and the Institute for Marine and Antarctic Studies. The competition will encourage innovative thinking in the next generation of fisheries managers and marine engineers by asking students to design bycatch mitigation devices to reduce the accidental capture of seals.

The competition encourages sustainable and innovative thinking, provides students with a great opportunity to gain valuable experience and to develop connections with the commercial fishing industry. The ultimate goal is to have the device commercialised and in use in our fishery where it will help reduce seal bycatch.

The competition is open now and entries close on 1 June 2015. The winner of the competition will receive $500, second place $350 and third place $150 in prize money. For further information please contact Nick Rawlinson at IMAS – N.Rawlinson@utas.edu.au

Did shortened nets reduce seal interactions?

12th March 2015

In March last year the newsletter reported on a project that aimed to reduce seal interactions with trawlers. The project was supported by AFMA through funding from the Australian Government and ExxonMobil Australia.

Reducing the chance of seal interactions is a logical step for the fishery which is actively working to improve its sustainability. Seals opportunistically feed on fish inside of trawl nets, and are occasionally caught in the net. Sometimes the seals are returned to the water unharmed, however some unfortunately drown.

Large trawl vessels are able to use grids that exclude seals from trawls; however, they are impractical and unsafe on the smaller vessels that are typical in the South East Trawl Fishery. Typical trawl nets are long, so that once a fish is in the net it cannot swim back out. South East fishermen hypothesised that seals would have a higher chance of swimming out of the trawl net if the net was as short as possible.

The “shortened cod-end” project aimed to compare the rate of seal interactions between a 27m “short” codend and a 39m “long” codend by alternating which net was used. Seal interactions are relatively rare so the project ran over a long time frame to ensure a large number of operations were completed; 683 shots (fishing operations) over 18 months. A vessel that regularly fishes off Tasmania’s west coast was selected because this is the area of the fishery with the highest seal interactions. The project was extended so it ran across the blue grenadier season, a time when seals are concentrated on Tasmanian’s west coast to establish if there were any factors in this part of the fishery that influenced the rate of seal interaction.

To ensure correct recording of the net type used and seal interactions, the skippers’ observations were verified by using colour coded nets and recording all shots on specialised video equipment that turned on and off automatically when setting and hauling the trawl net.
The project found that the short net had a seal interaction rate (proportion of shots with seal interactions) of 0.020 and the long net 0.018, however this small difference was not statistically significant. The project found no evidence to indicate that a short net catches less seals than a long one. Nonetheless the project was worthwhile and is an important step in the journey to reduce interactions.

SETFIA wishes to thank the Australian Government and ExxonMobil Australia for their financial support for the research project. Thanks also to the Phillip Island Nature Park who sat on the project’s steering committee. Finally thanks to the crew and owners of the fishing vessel the Western Alliance for alternating the two nets and agreeing to have video cameras installed for the life of the project.

Current seabird mitigations have reduced problem by 75%

17th September 2014

Warp deflectors, commonly known as ‘pinkies’, have been proven effective in reducing seabird interactions with trawl warp wires by 75% according to the results in the report by the Australian Fisheries Management Authority titled, Assessing the Effectiveness of Seabird Mitigation Devices in the Southern and Eastern Scalefish and Shark Fishery of Australia.

A summary of the report can be downloaded here and the full report here.  A video of pinkies in action can be found here.

The report examined the effectiveness over a two year period of two devices in reducing seabird interactions with trawl warp wires:

  1. warp deflectors (pinkies) – a plastic “pinkie” buoy that is attached to the trawl warp by a clip and connected back to the vessel on a rope
  2. warp scarers – a rope interlaced with semi-stiff streamers that is clipped onto the trawl warp.

Nine trawl boats participated in the trial in the Great Australian Bight and Commonwealth Trawl Sectors of the Southern and Eastern Scalefish and Shark Fishery.   A total of 124 trawl shots were observed to assess how well the mitigation devices worked. The trial was conducted in areas of high seabird concentration to ensure there was robust information on the effectiveness of each mitigation device.

Results from the trial showed that pinkies were most effective at reducing seabird interactions with warp wires while warp scarers had only limited success.

The trial also highlighted when seabirds weren’t at risk. No seabirds were observed interacting with the net itself because the net sinks rapidly and doesn’t spend much time on the surface. Importantly, only two heavy seabird interactions occurred at night, suggesting that trawling outside of daylight hours reduces the likelihood of seabird interactions compared to trawling during the day.

AFMA have advised that they will use information from the trial to improve existing practices including:

  • increasing pinkie size from 400mm to 600mm diameter (the size used in the trial)
  • removing the requirement to use physical mitigation at night
  • removing the warp scarer as an approved mitigation device

The Association will continue to develop and then trial bafflers and sprayers under the same methodology usingfunding from the Australian Government.  It is hoped these new mitigations might further decrease interactions.