Artificial Reefs

[archman]

yeah, I've never heard of a fake reef that didn't attract fisheries stocks either. Fishermen and scuba divers aren't generally the people running the complaints department, but rather a recent cadre of marine ecologists, fisheries scientists, environmentalists (well pretty much ALL of THEM), and in some cases financial planners. Several studies of artificial reefs in place have supported neutral or even negative impacts to the ecosytem, local habitat, and fisheries stocks (in no particular order).

Small surpise. There are very few instances of manmade alterations to a natural system in which the ecology improved. In fact I can't think of any off the top of my head.

The chief alarm by the fisheries folks is that artificial reefs may not in fact be enhancing fish stocks at all, but merely concentrating them into spots where they're far easier to monitor... and fish for!!

There's also a cute project done off oil rigs recently that looked at produced fish larvae. The baby fishes of course were sucked downstream and incapable of contributing to any community succession. The end result is that oil rig fishes are all made up of immigrants, and it STAYS that way.

The grouper scientists are all ticked off 'cuz the silly fish aggregate at the bottoms of rigs, shipwrecks, etc.. and then get promptly caught by the fishing folks. The biggest, oldest, and most reproductive members are the ones that have the most preference for artificial reefs, and they end up in somebody's freezer.

Low level pollutants are a hot topic these days, and a research mandate by the EPA. Toxicologists are finding that even minute amounts of certain compounds can do a great deal of damage, and "endocrine disrupters" are freaking out aquatic/marine scientists worldwide. The environmentalists are claiming that certain types of artificial reefs (ships mostly) can be great big repositories of strange odd compounds... that leach into the water column in very tiny amounts but over very long periods. It's the old "coal vs. nuclear plant" argument. They both will kill you, just one takes longer. Concrete reefs seem to be the way to go in this regard. They also last a lot longer.

There's other bad stuff reported or opinioned about in addition to what I've thrown together here. Not directly my field of study though, unless someone drops a ship to 1000 feet or deeper. This inherent bias in dumping fake reefs that happen to coincide with recreational diving limits I DO find interesting.

Still can't beat a rig dive for seeing big and awesome fishes. Just stop shooting them!

 

[FredT]

yeah, I've never heard of a fake reef that didn't attract fisheries stocks either. Fishermen and scuba divers aren't generally the people running the complaints department, but rather a recent cadre of marine ecologists, fisheries scientists, environmentalists (well pretty much ALL of THEM), and in some cases financial planners. Several studies of artificial reefs in place have supported neutral or even negative impacts to the ecosytem, local habitat, and fisheries stocks (in no particular order).

IOW those who have a financial ax to grind are the ones who bi**h. If the "regulators" and "would be regulators" didn't find problems there would be a significant lack of paychecks for them. Studies on the hundreds of ships sunk of the US 1940-1945 with tons of fuel, mercury & lead compounds etc on board find no contamination of benthic critters around the wrecks. The reason the wrecks have fish is they provide shelter and food. Shelter means more of the plankton grazers survive, so more predators show up there.

Small surpise. There are very few instances of manmade alterations to a natural system in which the ecology improved. In fact I can't think of any off the top of my head.

There are several, but they often aren't money makers but purpose built for enhancing the survival of a few species.

The chief alarm by the fisheries folks is that artificial reefs may not in fact be enhancing fish stocks at all, but merely concentrating them into spots where they're far easier to monitor... and fish for!!

There's also a cute project done off oil rigs recently that looked at produced fish larvae. The baby fishes of course were sucked downstream and incapable of contributing to any community succession. The end result is that oil rig fishes are all made up of immigrants, and it STAYS that way.

Almost all hard reef fishes are immigrants. Very few fish go from egg to planktonic larva to fingerlings to adult in a single place. The habitat necessary for each step is different!

The grouper scientists are all ticked off 'cuz the silly fish aggregate at the bottoms of rigs, shipwrecks, etc.. and then get promptly caught by the fishing folks. The biggest, oldest, and most reproductive members are the ones that have the most preference for artificial reefs, and they end up in somebody's freezer.

The answer is to dump WAY MORE out there, not less. Overwhelm the fishermen. Each wreck is an oasis of life, not in the least because shrimpers stay away from them. Grouper NEED cover, as they are an ambush predator. More cover = more places to ambush from, and more grouper. The number of juvenile 4" to 20" grouper on the wrecks is impressive, where the jewfish haven't taken over and stripped the wreck.

Low level pollutants are a hot topic these days, and a research mandate by the EPA. Toxicologists are finding that even minute amounts of certain compounds can do a great deal of damage, and "endocrine disrupters" are freaking out aquatic/marine scientists worldwide. The environmentalists are claiming that certain types of artificial reefs (ships mostly) can be great big repositories of strange odd compounds... that leach into the water column in very tiny amounts but over very long periods. It's the old "coal vs. nuclear plant" argument. They both will kill you, just one takes longer. Concrete reefs seem to be the way to go in this regard. They also last a lot longer.

Endoctrine disruptors are most often found in pesticides, which farmers pour by the kiloton on the land. Marshes can help clean them from the system, but most major river basins have had the marshes developed, or the COE has "channelized" things so bad they dont' function any more. The hydrocarbon "contaminates" stripped from most of those wrecks are actually food for some critters, and over time willl be eaten if some small form of water exchange is present. Ocean basins can suck up huge quantities of stuff if it's well diluted, with it eventually ending up as biomass or sediment. the "clean" WWII sites prove that point quite well. The problems don't come from wrecks, but from "other things" inconvenient to talk about.

There's other bad stuff reported or opinioned about in addition to what I've thrown together here. Not directly my field of study though, unless someone drops a ship to 1000 feet or deeper. This inherent bias in dumping fake reefs that happen to coincide with recreational diving limits I DO find interesting.

Still can't beat a rig dive for seeing big and awesome fishes. Just stop shooting them!

The rigs are heavily populated becasue there are SO MANY of them. The few "easy to get to" sites (the first 3 or 4 out of each inlet) are way overfished. Get out a bit farther out and the rigs all hold fish at one time or another. Most grouper and red snapper are migratory, as are all the pelagics so they do move around quite a bit.

As long as the fisheries rules are size based the "take" is regulated by recruitment rates. Spearfishing is much more selective and targeted than the indescriminate slaughter caused by the hook and line yahoos and their leavings, and greatly more surgical than strip mining done by shrimpers and other commercial fisheries. Catch limits for both spear and line rec fishing should at least be equal, with some favor given to the spearfishermen for their nonexistant bycatch.

FT

 

[archman]

excellent counterarguments from the other side of the coin.. you sure you're not a marine biologist?

 

[paolov]

there's some truth to it, '..add more..'

there's a site near where i go diving every weekend and it's called "BASURA" literally means trash.

this location is a blackhole for trash in the sea, and it is here that one can see uncommon critters lurking around the trash.

After all the most productive areas are river deltals to the sea and mangroves. fille dwith trash and filled with juvenile critters!!!

so those this mean we need to dump more?

 

[archman]

Most people would not consider trash as formal artificial reefs. Some scientists and environmentalists (few of which actually ARE scientists) would argue that all artificial reefs ARE trash. And then there's the folks that still go by the adage, "the solution to pollution is dilution."

I wouldn't dive near a river outfall personally, turbidity issues aside. There's too much weird junk in the water. Probably get run down by a tanker too...

 

[FredT]

you sure you're not a marine biologist?

Just an Ocean Engineer who has had to contend with the critters for 35 years. Hydrocarbons as food is very effectivly hammered home when microcritters eat the insulation off of armored power cable, without disturbing the armor!

FT

 

[quimby]

Originally Posted by archman

Small surpise. There are very few instances of manmade alterations to a natural system in which the ecology improved. In fact I can't think of any off the top of my head

Ok try something on land say the Maine woods 200yrs ago Ben Arnold took a continginet of Green mt boys on a raid to Canada and their method of travel was to live off the land. They got to NW Maine and damn near starved because the big woods had no small game (deer moose rabbit etc). Forestry methods (good and bad) and population have changed things. Now a there is more deer on the contient than EVER and etc etc etc. The"Native Americans" changed the "ecology" by burning and cutting for the the reasons above. Although some of it "aint prety" it always amazes me how a lousy bud can is absorbed into the eco system and becomes it own bio world.

And Kelphelper who cares if you dont like seeing Goodyear label on tires your estetic appreciation is not what makes the "garbage" tick. Its what is happening there now compared to when it was essentially desert. I ve seen tire reefs started 35yrs ago and the only neg is that the get sanded in and are lost to the habitat and us. Plastic bags and 6 pack rings yeah garbage needs to be brought out and nets and mono yeah also. But for most else as FREDT says have at Its a good thing (Maybe finding honest work for some legal begals, politicians and not to mention some eco nuts could also help)

 

[paolov]

so man made garbage (non-chemical) would and can be considered artificial reef? like refrigerators, chairs, knocked down walls, plastics casings (TV computer monitor etc.) in this case maybe PROJECT AWARE - PADI may instead of having these things removed, leave it on the seafloor.

and Project AWARE encourage the selection of materials acceptable as artificial reefs to be placed into the sea on a selected area?

paolov

 

[archman]

When an artificial reef is created where there previously was no hard bottom, you destroy the soft sediment community. Yes, there is something living in the "dirt". Arbitrary dumping can also create navigational hazards. I wouldn't like to think that littering was condoned because it "helps" the natural habitat. A similar argument was once made for letting the bears in Yellowstone feed out of garbage dumps, so they wouldn't "starve". That story didn't end well.

 

[FredT]

When an artificial reef is created where there previously was no hard bottom, you destroy the soft sediment community.

An yet the same artificial reef protects the surrounding soft bottom by keeping shrimpers away. The US continental shelf has hundres of thousands of square miles of mud or other soft bottom. We simply CAN'T dump enough stuff out there to upset the balance of soft bottom critters. Onthe other side of the coin each wreck protects several hundred yards of this bottom around each site from trawlers. Nets are expensive. Trawlers avoid snags like politicians avoid truth.

FT