Do artificial reefs increase total fish stocks, or merely concentrate existing stocks?

I dont know.

I would say that in general they do for the main reasons that they provide shelter from predators (not human) and plant food sources will be more abundant and grow better closer to the surface.

The reason that they might not work is that they also attract existing fish to a localised area where fishing is made easier. In that respect there would have to be restrictions.

I am not sure what effect shelter from predators would have, as it is mostly the predators we target. More plant food sources makes sense. A sandy bottom seems like a bit of a desert to me, whereas a reef with lots of things growing on it has more biomass at the bottom of the food chain.

The reason I ask is that I saw a few articles today about artificial reefs in moreton bay. These are not decommissioned ships or garbage, but custom made concrete blocks. They cost about $250 000 each, which wouldn't even get you a house these days, but still seems like a lot of money.

Depends upon the AR provided?
The Poor Knight Islands as a NO TAKE ZONE proliferated both number and size of fish in the area that the once angry Fisherman were happy chappies 6 years later with the 'Spillover' effect.

I'm not a big fan of Ex-Naval Ships being 'dumped' under the excuse of 'Artificial Reef' as not every 'dumped' ship attracts aquatic life, let alone proliferates aquatic numbers and life. Many don't.

Ex-Naval Ships are now mostly dumped for Scuba Diving Tourism, mostly in regards to Photographers, Tech Divers doing their 'Wreck Specialty' Certification and all things concerning $$$ ...no real concern for enhancing Aquatic Life.

If they did, they would have spent $3million (eg: Ex-HMAS Adelaide at Avoca, NSW) better by having a purposely built and designed AR that would have a far greater success rate for Aquatic Life towards proliferation of numbers and size.

Majority of Aquatic Life upon Wrecks & 'dumped' ships  - accumulates 'externally'. Only silt, a Wobbegong and Bullseyes reside further in.

The Yongala is a good example of much life around a Wreck, but many 'dumped' ships still have little life upon them even after 15 years. I've dived the immense Lermontov (NZ) and the Tugs of Eden - both have 'some' life around em, but nothing amazingly extrodinary.

Max Gleeson's videos upon Wrecks of NSW is probably the best collection to get the best impression of Aquatic Life around Wrecks as unlike most 'Commercial' Diver Doco makers, Max gets the 'Panoramic and whole Wreck' shots upon very clear viz days.

VARS's (Victorian Artificial Reef Society) has a motto "Trash for Treasure". Victoria dumps heaps of ships outside Port Phillip Bay, mostly for Dive Tourism - a metal version of the GBR.

Alas, 'dumping' ships leaves the door open for 'anyone' to dump 'anything' under the excuse of Artificial Reef, even with a lil' green sticker on it ;)
I could dump a stolen car and call it an AR  ::)
Nippon and USA use gigantic floating barges to dump MEGATONNAGE of rubbish out into the 'deep' sea.  :'( >:(
I guess Pilots are right when they say to me "We fly up to Heaven and leave the Toilet behind for you Divers to clean." >:(

Proper research and design for that particular environment under consideration for an AR would be far more successful in stimulating growth in size and numbers. When the house is full, the kids move out and that's where the Fishing Industry will benefit in a sustainable and long term way.

Currently, Commercial Fishing (if not Recreational too?) is now free to fish in all/any Reserve or Sanctuary Zone.
Why?
Many reasons I'm sure - like: they have run out everywhere else due to stupidity.
Because they can thanks to Politians, rather than Conservationists.
Money$$$ more than need to feed.
..and more. :P

Anything with an 'open overhang' provides great stimulus for Aquatic life.

From what I understand ( from the literature) YES they do..

Gizmo, which bit are you agreeing with?

Jas:


Quote:

Currently, Commercial Fishing (if not Recreational too?) is now free to fish in all/any Reserve or Sanctuary Zone.

What are you talking about?

Even if the effect is only to concentrate existing stocks, reducing fuel consumption and saving time could still be a real benefit.

freediver wrote on Jun 17^th, 2013 at 6:55pm:

Gizmo, which bit are you agreeing with? Jas: Quote: Currently, Commercial Fishing (if not Recreational too?) is now free to fish in all/any Reserve or Sanctuary Zone. What are you talking about?

"Do artificial reefs increase total fish stocks,"...YES they increase
total fish stocks

NSW (Liberals) have allowed Commercial Fishing to operate in Reserves and Sactuary Zones.

Can you post a link to more info on this please?

freediver wrote on Jun 17^th, 2013 at 1:18pm:

Do artificial reefs increase total fish stocks, or merely concentrate existing stocks?

If well designed they will provide more habitat for certain species, and potentially increase certain fish stocks.

Fair call FD. Will choof off to find one.  ;)

$250k concrete blocks sounds like a waste of money to me too.

I think that buys about 80 or so of them. It was $250k for the reef, or the upgrade to the reef,

Concrete is not a good material for AR's.
Besides being 'expensive' and 'heavy'.


...my mistake :-[
Most info I'm finding refers specifically to FORMER Reserves & Zones (eg: Solitary Islands) that now allow Commercial Fishing.
I must confer to my fellow Divers who are Conservatives/Enviro's/etc who told me word of mouth 'otherwise'.
They tend to 'over-do' things sometimes, just like Fishing has over the years  ;) :P

I have been told the same thing by fishermen.

Heavy is good. You don't want it to float away.

...or break up and crumble.
Haven't been into AR's for a while.
Trying to remember what 'is' the best material?

7 months back, I was down at Queenscliff Marine Centre in VIC. They have those concrete 'AReef Balls'.
Not bad, but they are small and only useful to 'some' species.
Snorkled the Ozone Wreck further north. Old paddlesteamer wreck that lays a short swim off the beach with a depth of 6m (the wheel sticks out of the water). It was an amazing display of aquatic life all around and amongst it. Plenty of plant life too!
I think it is because it is in a 'sheltered' part though.
Isn't smashed around as much by surge, current, pressure, etc.

Anything like Umbrella, Mushroom and if possible, the size of a Jetty or Wharf... to me is the winning formula from what 'associated' examples I've seen.

I think they would increase productivity. If you look at natural areas some are more productive than others. Actually there was a NSW fisheries manager on TV the other night talking about areas they have surveyed and one of the most productive areas they have found was Sydney Harbour!

PS: weren't you saying something about Sydney being the most overfished areas in Australia and crying out for marine parks?

Sydney Harbour has some major problems with pollution. I think there are limitations on pro fishing because of this, as well as advice on restricting consumption of fish from certain areas for recreational fishermen. Obviously that makes it easier to catch fish. The effect is similar to that of a marine park, though you are still faced with the question of would you eat them.

freediver wrote on Jun 19^th, 2013 at 7:02pm:

Sydney Harbour has some major problems with pollution. I think there are limitations on pro fishing because of this, as well as advice on restricting consumption of fish from certain areas for recreational fishermen. Obviously that makes it easier to catch fish. The effect is similar to that of a marine park, though you are still faced with the question of would you eat them.

Nice try but the show was a re-run. They were talking about commercial fishing still being in operation in Sydney Harbour. Also they were talking about the 'recent' banning of kingfish traps - which occured in the 1990's.

I apologise PJ. It was wrong of me to doubt your interpretation of your recollection of something you heard a bureaucrat say on TV the other night.

Most of Sydney is 'polluted', let alone the harbour.
But I say this admitting that since the 90's and the efforts taken. The Harbour waters have improved immensely from the feedback mostly from Divers I know who have been diving long before as well.

They've even had a submersible in Sydney Harbour these past few weeks looking around, like the Currajong Wreck. Alas, harbour viz hasn't been good atm.

There is no way I eat Seafood from Sydney! :P
I don't care if Doyles are offering 'Two-Heads' for the price of one with their 'Fish of the Day'.

I only consume from Wollongong and south.
Luckily here in Leeton, we get our Seafood from Eden.
Yum!

freediver wrote on Jun 19^th, 2013 at 8:35pm:

I apologise PJ. It was wrong of me to doubt your interpretation of your recollection of something you heard a bureaucrat say on TV the other night.

It's not hard to verify FD. How about this for starters:

http://www.dpi.nsw.gov.au/archive/news-releases/fishing-and-aquaculture/2008/sydney-harbour-thumbs-up


Sydney Harbour gets thumbs up from fishersSydney fishers have overwhelming declared Sydney Harbour as a great spot to fish, in one of the largest field-based recreational fishing surveys in Australia, Minister for Primary Industries Ian Macdonald said today.


Sydney fishers have overwhelming declared Sydney Harbour as a great spot to fish, in one of the largest field-based recreational fishing surveys in Australia, Minister for Primary Industries Ian Macdonald said today.

Mr Macdonald said the survey was part of a $2.2 million, two-year survey of NSW major recreational fisheries in the Greater Sydney Region.

"Results from the first stage of this research is great news for fishers - more than 70 per cent of fishers rated the Sydney Harbour fishery as good to very good with respect to the number, size and variety of fish available," Mr Macdonald said.

"Only 11 per cent of fishers considered it poor, which proves the vast majority of fishers value Sydney Harbour as a quality recreational fishing spot.

"More than 406 angling parties - representing 838 anglers - were involved in the Sydney Harbour surveys with around 70 per cent being shore-based and 30 per cent boat-based.

Minister Macdonald said Sydney Harbour is the oldest and most loved fishery in Australia.

"Importantly, this survey shows us that we are providing quality fishing areas for recreational fishers and ensuring sustainable fishing well into the future," he said.

"Anglers are catching a range of fish including snapper, yellowtail scad, yellowfin bream, yellowtail kingfish, tailor, dusky flathead, squid, sand whiting and silver sweep.

"It’s great to see that Sydney’s recreational fishers are catching a wide variety of fish, and are happy with the diversity and size.

"Staff are also surveying more than 25,000 fishing parties from across the Greater Sydney Region as part of the two-year project including the Hawkesbury River estuary, Port Hacking estuary, Norah Head, Terrigal, Long Reef, Bellambi, Port Kembla and Shellharbour.

"Survey staff are out on boats, at fishing spots and boat ramps interviewing fisherman about recreational fishing in the area. They are spending time finding out from recreational fishers about the time they spend fishing, what they catch and their views on the quality of the fishery."

The survey is jointly funded by NSW DPI and the Recreational Fishing Trust.

More information
Greater Sydney Recreational Fishing Survey


Contact: Jason Bartlett,

Phone: 0438 209 28

Media contact: Jason Bartlett, 0438 209 28

Thanks PJ. That was even more irrelevant than I expected.

Underwater footage of what I saw of Upper Harbour (towards Parramatta) just blew me away in how disgustingly toxic-looking it ...looked. It was a dead zone almost.
That was in 2000.
Underwater surveys by various Divers (not affiliated with Fishing or Govt paid 'Scientists') have just began at the start of this month. Along with the help of the handy 'Go-Pro' cameras. The true quality of the harbour will be revealed. These Divers are NOT on the take from 'local' Dive Shops either who would be totally bais in saying everything is 'Fantastic!'.

freediver wrote on Jun 19^th, 2013 at 9:12pm:

Thanks PJ. That was even more irrelevant than I expected.

You really put a lot of thought into your posts don't you? Your reply is even more air-headed than I expected.

Please tell me how it is irrelevant?

Are you asking me to prove a negative?

freediver wrote on Jun 19^th, 2013 at 9:22pm:

Are you asking me to prove a negative?

No, I'm asking you to justify your statement - one line inanities don't do that!