[Coral-List] Artificial Reefs

Thomas Le Berre thomas at seamarc.com
Wed Oct 23 12:57:14 EDT 2013

Dear John,

What a shame that you still have not been able to make it to the 
Maldives, I would have thoroughly enjoyed some discussions on the 
subject and you could have seen what we are up to here.
The problem of defining another word than artificial reef is that this 
new expression is going to stay among ourselves only. The general public 
will keep "artificial reef" in mind. In my opinion, we should just take 
the term as a theoretical object, which is a hard structure deployed by 
humans in water. I feel that a confusion in the general public is rather 
that you would hear: "this pile of junk is acting as an artificial 
reef". Well, it is an artificial reef...not sure what they are supposed 
to act like. Now, because the word is everywhere, what we really needs 
to be discussed is the first idea that comes to mind when the word is 
met, especially by environmental managers who are going to decide 
whether the project goes ahead or not. I have the feeling that now, the 
first impression is a negative one.
Given this meaning to artificial reefs, of course, hard engineering has 
created many of them (most of them sticking out of water) and I think it 
is the study of how the ecology has adapted around them that can lead us 
to better solutions, generally referred to as "soft engineering". 
Strangely, "soft engineering" is getting a rather positive impact in the 
same people's mind. In fact, it feels like the marine biologists just 
don't want to think of artificial reefs as possible soft engineering 
Regarding all this fish recruitment/attraction issue, this is very 
interesting, but I would think that practically, the simplest solutions 
are the best, and i am not sure it is always useful for the thought 
process to be overcrowded with all the theory.
I don't know anything about the oil platforms in the gulf, but when I 
think about it, I really don't see the need to remove them. At least, it 
is worth the experiment to keep them. But definitely, they should not be 
fished. Who is rightfully unhappy? The fishermen only right? They 
probably need to be explained that if the rigs were not in the sea, they 
just could not fish there in the first place. And also that these 
unfished hotspots are actually very good in terms of larval production. 
Whether the fish were attracted or recruited, I would think that each 
artificial reef would eventually reach its maximum carrying capacity (if 
not, even better). From that point on (but most probably before as 
well), the larvae would recruit to wherever the species was previously 
recruiting, which would be seen by the fish as equivalent to the  
artificial reef. The fishermen will find more fish in their natural 
spots where they have been sent back, thanks to a constant supply of 
larvae, and should be happy in the end.
It is very cheap to do, remove all the "floating parts" of the rigs, 
install a few surveillance camera to make sure no one comes to fish 
there and declare it banned for fishing within a radius of 2 km (?).
The great winners are of course the oil companies who are going to save 
a lot of money not only for the destruction of the reef but also for 
settling this issue rapidly, they need to reinvest that money in 
implementing square kilometers of solar panels in the middle of Nevada, 
because if we are not sure about all this artificial reef 
attracting/recruiting business, at least we are sure that this will be 
useful. Now if we think that this artificial reef is at least worth 
exploring, maybe some of the savings can also be diverted towards them 
and see if they cannot by any chance be optimized.
Tourism definitely looks promising as well...Do I miss something?
In short, I think we need to move on and think that human intervention 
can be beneficial and that artificial reefs may be key to how we look at 
coastal management in the future.


Thomas Le Berre
Managing director
Seamarc Pvt Ltd
www.reefscapers.com, www.marinesavers.com

To: "'Eugene Shinn'"<eugeneshinn at mail.usf.edu>,
	<coral-list at coral.aoml.noaa.gov>
Content-Type: text/plain; charset="iso-8859-1"

Regarding " However, there are non-fishermen citizens who thoroughly dislike
these artificial reefs because they make it easier to catch the fish. That's
a sociological side of the issue.", I would add that many fishery scientists
are cautious about these structures, who understand that;
1. many coral reef fish that are targets of fisheries are overfished,
2. in many cases, no legal and enforcement mechanisms to keep this fishing
under control are effective enough to do so,
3. and therefore, in many cases, an important rule in managing overfishing
is "do not make it easier to catch fish".

Jeff Polovina brilliantly pointed out a fundamental flaw in the logic of
using such structures to enhance local fisheries in his short article
"Should anyone build reefs?" (Bulletin of Marine Science 1989
44(2):1056-1057). Given that overfishing implies a substantial reduction in
a fish population, which therefore frees up substantial habitat for newly
settling fish, why would anyone think that the best strategy to getting more
fish would be to create more habitat?

However, this does not in itself rule out the idea of creating new habitats
for reef fish far from existing reefs , as Gene implies. Clearly such
habitats do provide settling spaces for larvae that would otherwise not
survive. If anyone sees a large grouper (more than 5 years old) present
within a couple of years of establishing the structure, as is often the
case, then that is a sign that fish are being attracted to the structure
from other areas. As I have pointed out in previous years (see archives), it
would take either an extraordinarily large artificial structure (or tight
system of smaller ones) in terms of hundreds of thousands of sq. m., or an
extremely low level of fishing, for a fishery of snappers or groupers to
continue being viable based only on fish that have recruited to the
structures as juveniles. Obviously, the fish caught on most artificial
habitats in heavily fished areas and less than a few thousand sq. m. in area
are primarily coming from other habitats. Those structures are referred to
in fisheries science as "fish attracting devices (FADs)". It is feasible
that tight systems of oil rigs or large rock barriers may provide enough
habitat area to support a sustainable fishery of reasonable size with a net
gain to fish stocks. However, I am still waiting for appropriate
quantitative fishery analyses (Schaefer analysis, Beverton-Holt analysis,
VPA, etc.) to be done on fish dwelling in such structures.



John W. McManus, PhD
Director, National Center for Coral Reef Research (NCORE)
Professor, Marine Biology and Fisheries
Coral Reef Ecology and Management Lab (CREM Lab)
Rosenstiel School of Marine and Atmospheric Science (RSMAS)
University of Miami, 4600 Rickenbacker Causeway, Miami, 33149
jmcmanus at rsmas.miami.edu?????http://ncore.rsmas.miami.edu/
Phone: 305-421-4814??

"Far better an approximate answer to the right question, which is often
???than an exact answer to the wrong question, which can always be made
?????--John Tukey, Statistician, National Medal of Science and IEEE Medal of

-----Original Message-----
From:coral-list-bounces at coral.aoml.noaa.gov
[mailto:coral-list-bounces at coral.aoml.noaa.gov] On Behalf Of Eugene Shinn
Sent: Monday, October 21, 2013 1:22 PM
To:coral-list at coral.aoml.noaa.gov
Subject: [Coral-List] Atificial reefs

As co organizer of the first International Artificial Reef Symposium
(1973) in Houston, Texas, I have since had ample opportunity to follow the
subject of artificial reefs and categorize the various divergent views they
evoke. Basically there are two schools of thought that tend to correlate
with peoples socio/political views. In simple terms they consist of, (1).
Artificial reefs simply attract existing fish and therefore do not increase
the numbers of fish and at the same time simply provide a convenient way to
dispose of old boats, streetcars, building materials, culverts, rubber
tires, and oil platforms.(2).
Artificial reefs actually increase fish productivity if placed in the right
locations regardless of the materials used. Of course there is truth in both
sides of the argument.

I first entered this field while diving (spearfishing and photography) under
offshore oil platforms off Louisiana and Texas. At the time I was a
geologist working for Shell Oil Co.Later when I was promoted from geology to
the environmental affairs department understanding the subject became part
of my daily job. Yes, we had old offshore rigs that needed disposal but
recycling the steel was more costly than purchasing new steel. If they could
be left in place or moved to established artificial reef sites there were
valid reasons to investigate their environmental functions.

What attracted my attention while diving under platforms was that those in
the northern Gulf were located on muddy bottom many miles from any natural
hard bottom. Surprisingly they were populated by an abundance of tropical
reef fish normally seen on Florida coral reefs.It became clear they had
arrived at the rigs as water borne larvae and encountered suitable refuge
and sources of food in the form of epiphytes, barnacles and other attached
organisms as well as an abundance of worms and shrimp in the surrounding
bottom sediment. Most of these fish larvae would likely have succumbed in
the hostile mud bottom environment of the northern gulf had they not
encountered these shelters. In addition there were lobsters living among the
cross beams well above the bottom. It seems unlikely that they arrived as
adults walking across many miles of muddy bottom. The sea floor beneath
these rigs consists of a thick layer of drill cuttings, fingernail-size bits
of rock, and yes, discarded debris, that also provide habitat for fish and
crustaceans. On the other hand the Jacks, Barracuda, and most
pelagic/migratory fish such as king mackerel that swarm around and under the
rigs, were likely attracted both for shelter and to prey on the other fish
that flourished there.
Those observations provide evidence for those who favor the other side of
the artificial reef discussion. Clearly some of both sides of the discussion
are true.

What was most striking about the platforms however, is the range of habitats
they provide that is not available on natural reefs. Different habitats
range from the surface to the bottom and Red snapper generally occupy the
rigs from bottom to the surface. I had never dived deep enough to see a red
snapper off the Florida Keys whereas they range all the way to the surface
under the rigs. Of course huge groupers of many similar species may have
arrived as post larval adults and simply took up permanent residence. There
is food/prey and shelter beneath the rigs regardless how they got there.

That rigs are good places to fish is well known to fishermen and divers in
the Gulf of Mexico. However, there are non-fishermen citizens who thoroughly
dislike these artificial reefs because they make it easier to catch the
fish. That's a sociological side of the issue. And of course there are those
who seem to be born to hate oil companies and naturally see no good in
them.Off the east coast of Florida there is yet another issue; conflict
between divers and line fisherman. I never saw this as a problem around the
rigs but probably existed in some areas. To mediate this conflict the Dade
County artificial reef program sank some old vessels and other objects,
including surplus army tanks, in water to deep for divers. They became the
favorites among line fishermen. I examined many of these "reefs" using a
submersible to determine the optimum depth to alleviate this conflict. The
study found that it is essential to place such artificial reefs well away
from natural reef bottom. The artificial reefs serve best when not in
completion with natural hard or coral reefs. On all of these artificial
reefs we examined there was no simple way to determine if they simply
attracted existing fish or served as primary producers. However, it was
clear in all cases that fish were feeding on algae and any crustaceans
attached to the objects. They do provide food and shelter.

These basic arguments, attraction versus production, will likely continue
well into the future as evidenced from range of opinions evident from recent
coral list postings. Gene

-- No Rocks, No Water, No Ecosystem (EAS) 
------------------------------------ ----------------------------------- 
E. A. Shinn, Courtesy Professor University of South Florida College of 
Marine Science Room 221A 140 Seventh Avenue South St. Petersburg, FL 
33701 <eugeneshinn at mail.usf.edu> Tel 727 553-1158 
---------------------------------- ----------------------------------- 
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