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Ocean Oasis!

Ships already scuttled for artificial reef/dive attractions

Ship Type Date Sunk Location
Rainbow Warrior Freighter 14 Dec, 1987 Cavalli Islands, New Zealand
G. B. Church Coastal Freighter Aug 1991 Portland Island, British Columbia
HMCS Chaudiere Destroyer 5 Dec, 1992 Sechelt Inlet , British Columbia
HMCS Saguenay Destroyer June 1994 Lunenburg, Nova Scotia,
HMCS Mackenzie Destroyer 16 Sept, 1995 Sidbey, British Columbia
HMCS Columbia Destroyer 22 Jun , 1996 Maud Island, British Columbia
356 (Russian) Frigate Sept 1996 Cayman Brac, Cayman Islands
HMAS Swan Leander Class Frigate 14 Dec,1997 Dunsborough, Western Australia
HMCS Saskatchewan Destroyer 14 Jun, 1997 Nanaimo, British Columbia
HMNZS Tui Oceanographic Research Feb 1999 Tutukaka, New Zealand
HMCS Yukon Destroyer July 2000 San Diego, California
HMNZS Waikato 113m Leander Class Frigate (F55) 25 Nov 2000 Tutukaka, New Zealand
HMCS Cape Breton Escort Maintenance 20 Oct, 2001 Nanaimo, British Columbia
HMAS Perth Destroyer 24 Nov 2001 Frenchmans Bay, Western Australia
Speigel Grove Transport Ship June 2002 Key Largo, Florida
HMAS Hobart Destroyer 5 Nov, 2002 Yankallia, South Australia
Lena Toothfish Trawler 19 Dec 2003 Bunbury, Western Australia
HMS Scylla 113m Leander Class Frigate 27 Mar 2004 Whitsand Bay, Plymouth, UK
South Tomi Toothfish Trawler 18 Sep 2004 Geraldton, Western Australia
Saxon Ranger Fishing Trawler 22 May 2005

Rockingham, Western Australia

HMAS Brisbane Destroyer

31 July 2005

Mooloolaba, Queensland Australia

HMNZS Wellington 113m Leander Class Frigate (F69) 13 Nov 2005 Wellington, New Zealand,

USS Oriskany Aircraft Carrier 17 May 2006

Pensacola, Florida.

Captain Greg Mickey 183-foot support vessel 23 June 2006 Frying Pan Shoals, New Orleans, USA,

Troy D 55m Coastal Trader 10 Feb 2007 Tasmania, Australia,

P29 52m German Patrol Boat 10 Sept 2007 Cirkewwa, Malta,

HMNZS Canterbury 113m Leander Class Frigate (F421) 3 Nov 2007 Bay of Islands, New Zealand,

 

Ocean Oasis
The Worldwide Ship Reefing Programme

The Worldwide Ship Reefing Programme is well underway with each of the 23 ships listed above testament to the benefits derived from these living jewels under the sea.

Artificial reef construction and research has primarily been centred in Japan and the United States, although other countries such as Australia, United Kingdom and New Zealand are now implementing their own artificial reef initiatives.

The first artificial reefs in the United States were constructed in the mid-1800's (Stone, 1974), although the Japanese had begun constructing artificial reefs several hundred years earlier (Ino, 1974). The United States utilises the reefs primarily to enhance sea-life for recreational fishing and more recently as diver attractions. Reefs in Japan were mainly constructed to enhance commercial fishing.

In 1976, Japan began a 6 year program with $250 million for artificial reef projects. Of this $65 million was used for research alone. In 1982, the Japanese government started another 6 year plan with approximately $500 million to be spent on artificial reef implementation. (Grove and Sonu, 1983)

Artificial reefs have been a tremendous help in coastal Alabama to both the commercial and sport fishing industry. Catches of reef fish species, such as red snapper and grey triggerfish, probably exceed all other coastal areas in the United States. The Alabama Marine Resources Division along with a great many private fishers have been intensely active in constructing artificial reefs. Other states are following the example set by Alabama and are planning or already have in place their own special reef-building zones.

Canada and the State of Florida, USA, have completed 100's of artificial reef programmes, using decommissioned ships, concrete type constructions and more recently sinking retired drilling platforms into deeper water. Retired ships continue to be a significant source of material for artificial reefs in these regions.

 

How an artificial reef works....

Encrusting and reef building organisms such as algae, sponges, gorgonians, and other benthic organisms, require solid substrate to incorporate a reef community; surface area is the limiting factor. Many areas are devoid of this prerequisite, consisting of vast expanses of sand and mud (It is important to note, however, that these seemingly barren sand and mud habitat areas play an important and valuable role. While in some instances they may not be as diverse as a reef community, many times they are much more productive [mud and sandy bottom areas produce a rich supply of polychaete worms, crustaceans, and other benthic invertebrates that are an important forage source for other marine species]. Yet, benthic areas comprising of sand and mud are not in short supply, therefore the addition of localized artificial reef structure is not predicted to have a negative overall effect). The deployment of artificial structure on the seabed has an immediate effect: algae begins to grow, encrusting organisms, drifting as planktonic larvae in the water column, secure themselves to every available surface, sea turtles find temporary sanctuary amongst protective overhangs, and pelagic fish soon associate to the vertical relief. The subsequent colonization into a functioning reef evolves over time, attracting numerous permanent finfish and invertebrate species, as well as larger pelagic and transient organisms such as shark, barracuda, kingfish, rays, etc.

Artificial reef structure provides two primary services critical to the survival of most marine organisms - protection from predation and an ample forage source. Symbiotic relationships, such as the cleansing of parasites, are an additional benefit that attracts organisms to reef communities. The presence of complex benthic habitats, typical of artificial reefs, provides many interstitial areas for juvenile organisms to hide, reducing the potential for predation. It is a logical assumption that this increased survivability of pre-recruits, in a particular species, will eventually increase the future spawning stock biomass, and thus the fishery.

The establishment of a reef community produces large communities of diverse benthic organisms such as sponges, gorgonians, hydroids, anthozoans, bryozoans, crustaceans, and algae. This abundance of benthic species creates an ample food supply for recreationally and commercially important marine species such as crabs, snapper, lobster, flounder, etc. Furthermore, species such as these may supplement the diet of larger piscivores, which have been noted in copious quantities on many other artificial reefs. This abundance of prey attracts numerous species to artificial reefs, helping to establish a successful and thriving, albeit artificial, community.

The following are case studies on several of the shipwrecks listed at the beginning of this page.

 

Case Study - HMCS Chaudiere

One such vessel is the HMCS Chaudiere, a decommissioned destroyer escort, sunk off British Columbia on December 5, 1992.

As part of the monitoring of the Chaudiere post sinking, several studies were undertaken. These included Water Quality Studies, Colonisation Evaluation, Oil, Grease, PCB and Heavy Metal Analysis.

Monitoring of the HMCS Chaudiere ceased 4 years after it became apparent no adverse effects were identified from sinking the vessel as an artificial reef. The only change noted after the first 3 studies, Feb 1993, Sept 1993, Feb 1994, was the mass colonisation of the ship by over 150 species of marine life and a noted increase in the recreational catch by fisherman in the surrounding area.

Monitoring Survey Results, February 1993 Waste Management Division, Environmental Protection Conservation and Protection, Pacific and Yukon Region. David L.S Ellis, P. Eng. Reg Data Report DR93-01.

Key points

2 months after sinking, the entire outer surface of the ship is covered in algal growth. Plankton was observed in the water column outside and around the ship. The outer hull supported a variety of organisms including rockfish, starfish, shrimp and sculpins. Adjacent to the ship large numbers of juvenile pelagic fish were noted.

Water sampling from 5 separate test locations on the ship indicated that water quality conditions around the vessel were comparable to the 2 natural reference sites. There has been no elevation in the concentration of any of the water quality parameters measured. These parameters included analysis for oil and grease, trace metals and fibres.

Sampling locations on the vessel were as follows: Engine Room, through holes in the vessel bottom Generator Room ahead of the mortar well, deck 3 Bow, at opening cut in the deck forward of gun turret Bridge, inside command position. Petty Officers Mess, Deck 3

Natural reference sites: Shoreline, northeast of vessel Seabed, 300 metres southwest of vessel at 30metres depth.,/p>

Monitoring Survey Results, February 1994 Waste Management Division, Environmental Protection Conservation and Protection, Pacific and Yukon Region. Kay Kim. Reg Data Report DR94-01.

Summary

This summary includes results from a follow-up monitoring study in September 1993, performed by Environment Canada with assistance from Royal Canadian Mounted Police Vancouver Dive Unit Division. Sampling locations were identical to the first post sinking study, done in February, 1993.

Fecal coliform, fibre oil & grease and trace metal analysis showed no differences between the sampling locations on the vessel to the reference sites. Results were similar to analysis results in Feb, 1993. Based on these parameters all marine stations sampled met the shellfish growing water quality standards as set by Environment Canada.

A considerable portion of the exterior of the vessel has been colonised by Ciona intestinalis (crystal vase tunicates), barnacles, and mussels since the original baseline study. Jelly fish, pelagic fish, a wolf eel, anemones, starfish and a ling cod were found in or on the vessel. Ciona intestinalis were also observed in the interior of the vessel.

Data collected on the water quality of the Sechelt Inlet in the vicinity of the HMCS Chaudiere during the February 1993 and September 1993 surveys indicate that the vessel has had no apparent negative impact on the marine environment. There has not been any elevation in the concentration of any of the water quality parameters measured. Ref: Elliss, D 1993; Shreier, H, 1989.

 

Case Study - G.B Church

Sunk: Portland Island on August 11, 1991, 175 foot (53 meter) 530 tonne Coastal Freighter. (Built in 1943 in Goole, England)

The G.B. Church was the first artificial reef project in British Columbia, Canada. It served an important role as a proving ground for the larger and more complex naval artificial reef projects that were to follow. The G.B. Church project was completed over a two year period. She was sunk in August 1991 within the Princess Margaret Marine Park off Portland Island near Sidney, British Columbia.

On this sandy bottom the ship was quickly overcome with rich marine life including octopus and wolf eels and today is testimonial to the positive environmental impact that artificial reefs have on the marine ecosystem. Not only do artificial reefs promote marine life, they also reduce diver impact on surrounding natural and historical shipwreck dive sites by diverting diver traffic from those sites.

Monitoring Survey Results, March 1994 Lands and Parks, Ministry of Environment, The Province of British Columbia. Subsea Enterprises Inc, BC. Reg Data Report V7G 1L3

The density of marine life on the G.B. Church varied from one part of the vessel to another, but was generally greater on the outer, exposed surfaces of the hull.

Close to 100 species of easily visible marine organisms were found to be living on or associated with this artificial reef; 62 invertebrates, 20 fishes and 14 species of seaweeds. Crustaceans were the most varied group on invertebrates with 17 species recorded, followed by molluscs (14), urochordates (9), echinoderms (6), annelids (5), cnidarians (5), bryozoans (4), sponges (2) and brachiopods (1). Among the fishes, sculpins were the most diverse with 8 species recorded, followed by rockfish (5), greenlings (3), pricklebacks (1), gobies (1), surfperches (1) and poachers (1). Among seaweeds the red algae was most diverse with 8 species recorded, followed by brown algae (5) and green algae (1)

The ship remains in the exact position that it landed on in August 10, 1991. All rails and stairways are in good condition. There is only minor corrosion in this area. No large accumulations of debris were found in the hold area. Minor accumulation of silt and shell hash can be found on the deck of the hold. The strongbacks (transverse beams that run across the top of the hold) are secure in their mountings and have good welds.

The superstructure and decks were found to be safe and secure. The wheelhouse and bridge wings are in good condition. The engine room is clear of hazards with all deck plates in place and welds secure.

The walls inside the hold, supports a markedly different assemblage of organisms than the outer hull. This inner site is not exposed to tidal currents or swell. Depth is at 20m. Coverage is estimated at 60%. The most conspicuous organism is the rock oyster. Other species present include tubeworms, encrusting yellow sponge and lacy bryozoan. The floor of the hold is home to many striped shrimp. Diversity is lower (8 species) than the outer hull, although abundance of one particular species, the rock oyster, is high (estimated at 600 per square metre).

The inside walls of the accommodation area, on the boat deck level, is subject to very subdued light levels since it is inside the ship. Depth here is at 13metres. Coverage by marine species is estimated at 80%. Diversity is relatively high (10 species) and an abundance of certain species (ie, tubeworms, is extremely high) A school of striped sea perch was observed swimming through this area. The overhead beams are well colonised in some sections with considerable numbers of small plumose anemones.

The outer hull on starboard stern is fully exposed to tidal currents and swell. Depth is at 16 metres. Coverage estimated at 80%. This site is dominated by impressive bouquets of parchment tubeworms which extend out from the hull up to 10cm. Also observed at this site were tunicates, lacy bryozoans, tubeworms, barnacles and encrusting sponge. Both diversity (15 species) and abundance are high at this site.

Under the hull at the bow, a dark cave like habitat has been created. The underside of the hull at this site is heavily colonised by plumose anemones, some reaching 25cm in height. There are also very large numbers of striped shrimp living on the hull. Densities were estimated at more than 300 shrimp per square meter, which is the highest the researcher had ever observed. At the time of these observations a 1.5metre lingcod was seen living under the ship just where the hull met the substrate.

At several spots on the hull large spawning masses of dog whelks were observed laying eggs.

The foredeck is home to schools of juvenile rockfish and encrusted with a layer of barnacles and tiny tubeworms. The foremast and foredeck are colonised by several species of red algae and a few species of brown algae. The foremast is colonised also by barnacles and other small invertebrates, including compound tunicates.

This ship is progressing well as an artificial reef and has an impressive colonisation through most parts of the vessel. No adverse effects to the environment were noted. Significant increase to recreational catch has been noted in the surrounding area.

 

Case Study - HMAS Swan

On 13 September 1996, HMAS Swan was decommissioned from the Royal Australian Navy. During her career, HMAS Swan steamed almost 800,000 nautical miles. The HMAS Swan was sunk on the 14 December 1997.

In 1995 the Australian Government indicated that HMAS Swan would be given to the Government of Western Australia. The WA Government then advertised for expressions of interest for a future use of the ship. The applications received were then considered by HMAS Swan Steering Committee (which included environmental, industry, marine safety and marine transport representatives). The majority of the expressions suggested sinking the ship as a dive site (one was for it to be preserved as a floating museum but  was withdrawn when they realised most equipment was to be removed for spares).

The ship was moved to Bunbury where over the next year, the Geographe Bay Artificial Reef Society worked to prepare the ship for sinking. As well as cleaning the ship (removing all traces of oil from the bilges and tanks), all electrical cabling, false ceilings and insulation had to be removed. One of the major tasks was to make the ship as safe as possible for all divers. This involved sealing some compartments (the engine room is inaccessible, the entrances having being grated over) and cutting dozens of access holes in the hull (there are 14 alone in the starboard side and two at the stern) and between compartments.

On 14 December 1997, an estimated 20,000 spectators, both on shore and aboard the 300 vessels surrounding the ship, witnessed the sinking event.

 

Case Study - GreenPeace's RainBow Warrior

Thirteen years after the sinking of the Greenpeace flagship Rainbow Warrior, Gavin Anderson dives her wreck, now a brightly coloured artificial reef in the South Pacific.

Two and a half years after her sinking, the raised and patched-up Rainbow Warrior was towed from Auckland, New Zealand, to the Cavalli Islands, three hours to the north, to be sunk as an artificial reef. On 14 December, 1987, a position was chosen, not far from Motutapere Island, and the vessel's seacocks were opened. Inquisitive triggerfish were checking out the wreck within 30 minutes of her placing.

The first thing that struck me as I descended onto the wreck of the Rainbow Warrior was the colours. I have never seen such beautiful colours on a wreck before: reds and yellows, pinks and blues - all the colours of the rainbow; it's as if even the marine life is in sympathy with the old girl. There were fields upon fields of brilliant jewel anemones. And as I moved out to get a panoramic picture of her, I glimpsed something totally unexpected. At first I thought it was some unusually fast new species of fish; then I realised it was a bird. It came like a targeted missile right towards me, swooping past, and then turning away and heading towards the bow. I watched it disappear into the distance, in awe of its sleek swimming style. A cormorant had stopped by to do a spot of fishing!

The wreck sits on sand in about 25m of water. The buoy is usually tied on to the stern section, and on a good day, when visibility is 20m or more, you can see the whole stern section and a good part of the ship as soon you descend the line. Most of the time visibility is at least 15m, and on an exceptional day it can reach 30m.

I found the stern colours amazing; even at depth they were still visible. Apparently, jewel anemones are able to absorb light at a low level of intensity and emit it at a higher one, so we could still see these gorgeous colours at an incredible 20m. I stayed at the stern for some time, mesmerised by the amazing scene in front of me.

When I had almost exhausted a whole film, I began to explore the rest of the wreck. Although I discovered her bridge had collapsed, probably from surf impacting from above, and a good deal of her railings were bent or missing, I found her otherwise still intact. Her relatively shallow position has allowed a good covering of kelp and algae to take hold on her upper surfaces.

There is so much life encrusting her that I found it impossible to see exactly where the two explosions that sank the ship had taken place. The patch-up job was remarkably good. Time has also covered up the famous Rainbow Warrior Aberdeen lettering on her stern, and the dove and Greenpeace markings on her hull. Her famous rainbow colours have also disappeared, but they have been replaced with huge gardens of jewel anemones instead, which do the same job, but even better!

Her relatively small size, (45m long) and her shallow depth made her great for exploration and photography. I had time to circumnavigate her a couple of times and check out her most accessible compartments, including her galley and saloon. Inside I found it very dark and eerie. Moray eel and crayfish are known to lurk in many parts of the wreck.

Around the wreck there were plenty of subjects to photograph, from little blennies peering out of small holes to small schools of leatherjackets and blue maomao. Down on the deck the odd kelp fish seemed as at home here as in his normal habitat. Here I almost bumped into a huge scorpion fish, blending into his surroundings perfectly. Up on the railings I searched for nudibranchs, but I couldn't find any, so contented myself with a few more photographs of jewel anemones.

The bow was even more photogenic than the stern. Here the railings are still complete, and are festooned with anemones and the odd piece of kelp. I had taken two cameras with me, which enabled me to take both wide angle shots of the wreck and close-up shots of the brilliant marine life living on her. As well as the dazzling array of jewel anemones, I found curious little triplefins and several blennies. I could have spent hours just photographing them. As I slowly made my way up the buoy line, I looked back down at the wreck. I wondered when and if I would ever get to dive her again.

 

Case Study - HMNZS Tui

Sunk: February 1999 off Tutukaka (near Green Hill), Northland, New Zealand New Zealand Navy 'Conrad' Class Oceanographic Research Ship.

Sinking the former naval survey ship Tui just off the Tutukaka coast thrust Northland into the forefront of the rapidly growing international pastime of wreck diving.

The Tui was cleared of any obstacles, non-ferrous metals and the any possible snags were removed. Oil, grease and any other potential contaminants were removed and areas steam cleaned.

A focus on diver safety, several holes were cut in the hull to allow easy access and exits for divers. A way in was matched by a way out.

Once cleaned to environmental standards, the stop cocks were opened and the Tui sank from the view of the hundreds of spectators on hand to watch the spectacle.

Within minutes of the Tui sinking schooling fish had found a new place to explore. Two years later the Tui was the focus of a colonisation study which found over 50 marine species living in, on, or around the ship, many in abundance.

Schooling fish, reef fish, crayfish, eels are amongst the many species that now live on an entirely algae covered ship. Seaweed is well established and the Tui is following the example of the Rainbow Warrior in becoming a colorful living jewel in the sea.

 

Case Study - HMNZS Waikato

HMNZS Waikato, F55. Length 113Metres. Sunk off the Tutukaka Coast, Saturday 25th November 2000. NZ Navy Leander Class Frigate, Group 2 Construction.

Frigates and destroyers are noted as one of the best ship constructions for artificial reef deployment due to their inherent design strength. Highly compartmentalised and constructed from mainly steel, these ships have shown worldwide they can withstand the vigour's of the sea. Very narrow at only 13metres compared to its overall length of 113metres, this style of warship creates very little resistance to seas passing over and around them.

Strength aside, the Waikato sustained damage due to the incredible speed of sinking, taking only 2 minute 40 seconds, splitting at the construction join directly in front of the bridge on impact with the seabed. Described as if cut by torches with a rule line, the area of damage is a known weakness point on this particular group of Leander Class frigates on an otherwise very solid ship.

This construction group (2) of frigate was known to incur splits in its hull at this point and Leander frigates constructed after this (Group 3) were improved and highly reinforced in this area. Notably in the NZ Navy the remaining Leander frigates, the HMNZS Wellington and the HMNZS Canterbury, are both group 3 construction. Nearly a metre wider than the Waikato and with a different construction technique when joining the superstructure to the bow section, this damage is unlikely to re-occur should these vessels also become artificial reefs. (P Crosby, Naval Architect, Chief of Naval Construction, RNZN)

Surpassing the colonisation speed of the HMNZS Tui, probably due to the more energetic water flow around the ship, the Waikato is proving to be an exceptional investment for the region.

8 months after sinking, the Waikato is already 80% covered by algae and some 30 marine species have been noted around the ship.

Following is a letter from Tutukaka Coast Promotions as to the impact from sinking the Waikato and Tui to the region.

    Tutukaka Coast Promotions (inc)
    PO Box 404 Whangarei,
    Ph 025 810826
    Fax 09 4343 704

    Re: Benefits of shipwrecks off Tutukaka

    Since the sinking of the ex HMNZS Tui on the 20th February 1999 and the ex HMNZS Waikato on the 25th November 2000 there have been numerous benefits to the local community.

    The area has become the Icon of New Zealand diving, earning itself the name of "Dive Capital" of New Zealand. The substantial exposure of the media both in New Zealand and the international arena confirm this status. As a consequence there has been a significant increase in diver visitors numbers to our area. The generated interest in diving in the Tutukaka area has also attracted the interest of the Natural History unit of Dunedin. They, in the last month, have produced a documentary on the nearby Niagara shipwreck and one about free diving. Previously the sinking of the Waikato had been show all over Europe, United States (CNN), Hong Kong, and Australia. We still get overseas visitors commenting on viewing the sinking in their home countries.

    On good diving days (weather wise) we have had as many as 150 dives per day on the new shipwrecks. Local and other dive stores from all over New Zealand are enjoying these wrecks on a very regular basis. There have been a number of divers specifically coming to NZ to dive these wrecks! Whilst no official statistics have been collected, a number of dive operators have experienced a 30 % increase in numbers in 2000 and again a similar increase in 2001.

    Local accommodation providers have also had significant increases in the numbers of divers staying in the Tutukaka area. And due to the fact that there are now 2 ships and the Poor Knights Islands they are staying longer in the area to be able to dive all these destinations. Divers both from the domestic market and our international visitors are also coming back more often. We now have a problem in the area with a lack of accommodation!

    The café and restaurant scene report far greater turn over, and have increased opening hours and had to take on more staff. Some have increased turnover of over 40% in the last two years. Also a new eatery was established last year and has since the start up increased the size of the business.  The local "shop" has doubled in size and has been markedly busier. In fact it cannot grow any bigger!

    New investments in the area are a new camping ground/backpackers that is currently under construction. Plans for a new motel are also well underway. The existing motor camp has also built a number of extra backpacker units to cope with the increased demand for accommodation on the coast.

    Other small businesses such as the farm park and a new river eco tour boat are being developed to provide further options for visitors in our region. With the increase in numbers of visitors arriving the viability of such ventures is far greater.

    Exposure on the recent TRENZ tourism event in Christchurch has established Whangarei as the dive capital in New Zealand and has given it the recognition as an Icon destination in Northland, which now will be, marketed world wide. Efforts are now being made to get the Tutukaka loop road on the "Twin Coast Discovery Route" with the full support of "Destination Northland" and the Whangarei Tourism Trust.

    International exposure and recognition was further achieved through a partnership deal with Air New Zealand, they are now also marketing diving in Tutukaka worldwide. (see www.diveinthepacific.com).

    Waikato University has one of their students doing a masters program on the marine settlement on the vessel whilst another is starting to do a masters on the economic impact of the "sinking" on the local community. These activities again raise the profile of the area to the benefit of the local community.

    The spectacular growth of marine life on both ships and the huge numbers of fish both in numbers as in species (With the Tui there are over 50 species observed on and around the ship) illustrates the ecological success is greater than anticipated.

    In fact all this has happened during a summer that was probably the worst in the last 10 years. Due to many prevailing easterlies this season we had to cancel close to 50% of the planned trips to the shipwrecks. However it must be seen as a long-term investment for the community as the shipwrecks may well be in existence for a period of over 100 years.

    It is obvious that the sinking of these ships, now marketed as the "Twin Wreck Steel Adventure" has been of significant benefit to our local and regional economy. As these benefits are shared by the wider community it is therefore deserving of the full support that community organizations can contribute.

    Jeroen Jongejans,
    Project Manager Tui and Waikato

 

Following are some reef study reports...

Effects of Artificial Reef Deployment on nearby Resident Fishes Bulletin of Marine Science. Alevizon & Gorham)

The effects of artificial reef deployment on fish communities residing in areas surrounding deployment sites were quantitively measured. Fishes inhabiting sand plain habitats in two 6 hectare study sites in the vicinity of two small test artificial reefs were censused prior to artificial reef deployment and then quarterly for over a year.

Two small arrays (2 x 1 x 1.5metre) of artificial reefs were placed as experimental reefs on the sand habitats.

Quarterly studies were completed over a year. The number of fishes inhabiting the arrays stabilised in approx 4-6 months. The surrounding natural habitats showed no significant changes in species richness, total numbers of juvenile or adults, or in densities of the 5 most abundant species.

A ship was then sunk as a large artificial reef structure in the area at the completion of this study. The ship was noted for it complexity of different habitats. Vertical relief, horizontal decks, overhangs, dark areas, areas washed by currents and sea action, others internal and void of sea action.

Nine months after deployment of the larger more complex reef, the numbers of adult fishes residing on the large artificial reef had more than doubled, but had remained essentially unchanged in the surrounding natural control sites. These adult fishes were mainly snapper (Lutjanidae) and grunt (Haemalidae).

The results demonstrated that larger artificial reefs result in marked increase in the numbers of resident reef fishes, without diminishing numbers of fishes dwelling in nearby natural sand plain or natural reef habitats.

Although the deployed artificial reef covered less than 1% of the bottom area of the site surveyed, it resulted in an increase of about 20% in the numbers of adult fishes (and a roughly doubling of the fish biomass) of the study area. Thus, we interpret our results as demonstrating that artificial reefs can function to dramatically increase the populations of selected species without negative impact on fishes dwelling in nearby habitats. Artificial Reef Research - A Review Bulletin of Marine Science. (Bohnsack & Sutherland)

 

Abstract

This abstract is based on research of 413 references. 129 of these had appeared in peer review journals.

Artificial reef literature was critically reviewed to determine what knowledge about the biology, ecology, and economics of artificial reefs had been scientifically established and to identify and recommend future projects, areas and methods of research. General agreement exists that artificial reefs are effective fish attractants and an important fishery management tool.

Artificial reefs have become an important and popular resource enhancement technique. Artificial reefs improve fishing by concentration of fishes and by increasing natural production of biological resources. The purpose of most artificial reefs has been to improve fisheries by increasing the harvest of algae, lobster, other shellfish and fishes. In the United States almost all fishery improvement reefs have been built to attract adult fishes. In Japan artificial reefs have also been built to improve spawning, recruitment and survival of earlier life history stages. (Arlisle et al, 1964, Petit, 1972, Paxton and Stevenson, 1979, Mottet, 1981, Vik, 1982, Buckley, 1982, Grove and Sonu, 1983, Okamoto, 1983)

 

Seeding of Reefs

Seeding algaes or invertebrates on an artificial reef can greatly increase productivity and accelerate colonisation. Seeding artificial reefs with algae, oysters, clams, abalone and sea urchins has been done frequently in Japan (Mottet, 1981). In The United States, abalone and kelp have been experimentally introduced on artificial reefs (Carlisle et al, 1964; North & Hubbs, 1968; Grove et al, 1982). In tropical waters corals have been transplanted to establish new artificial reefs (Maragos, 1974; Bouchon et al, 1981). Fishes also colonise artificial reefs quite rapidly (Russel et al, 1974) The first fishes appear within hours after reef material has been deposited. (Molles, 1978; Turner et al, 1969)

 

Artificial Reef Function

Fishes use artificial reefs for shelter, feeding, spawning and orientation (Kojima, 1956; Gooding and Magnuson, 1967; Hunter and Mitchell, 1967; Kakitomo, 1982, Ogawa, 1982; Yoshimuda, 1982) Artificial reefs function by either aggregating existing scattered individuals, or they allow secondary biomass production through increased survival and growth of new individuals because of shelter and food resources provided by the reef.

 

Comparison of Artificial Reefs with Natural Habitats

Most studies on the effectiveness of artificial reefs have attempted to compare artificial reef communities with communities on natural reefs or in randomly chosen control areas. In almost all cases artificial reefs had higher density and biomass than randomly selected bottom control areas. (Rodeheffer, 1939; Arve, 1960; Clarke et al, 1967; Petit, 1972; Pierce, 1967; Deroche, 1973; Chapman, 1975; Alfieri, 1975; Lim et al, 1976, Prince & Maughan, 1979, Prince et al, 1979; Walton, 1982). Walton (1982) found about four times the density and nine times the biomass of flatfishes and eight times the biomass and density of all fishes on artificial reefs relative to control reefs. Clarke (1976) found 35 times greater biomass on artificial reefs than on open bottom areas.

Artificial reefs with bulk volumes between 2,500 and 130,000 cubic metres maintained larger schools of fish (volumetrically) than natural reefs of the same size. Smaller size reefs have also shown significantly greater fish density than the same size natural reefs. (Bohnsack, 1979; Talbot et al, 1978). A common explanation for the greater biomass and density of fishes on artificial reefs versus natural reefs is that artificial reefs are more complex and provide much more varied cover than natural reefs (Smith et al)

Many studies have shown greater fishing catches at or in the vicinity of artificial reefs than at control sites. (Rodeheffer, 1939; Moseley, 1961; Turner, et al, 1969; Buchanan, 1973; Wickham et al, 1973; Crumpton and Wilbur, 1974; Fast, 1974; Myatt, 1978)

Optimum Design of reef Yoshimuda (1982) found attractiveness generally increased with greater reefs size although small reefs could be productive as well. Rounsefall (1972) suggested that artificial reefs should be at least 5,700 cubic metres to maintain self-sustaining fish populations.

Greater vertical relief supported more fishes on artificial reefs (Molles, 1978; Walton, 1979; Ogawa, 1967). Ogawa found certain species were attracted by the height of reefs while others were equally attracted by increased horizontal size.  Mottel (1981) concluded that reef height was important but probably not so important as total area and complexity. The profile of a reef may be more important than actual height. Reefs with near vertical sides are considered best because they increase turbulent flow, producing attractive sounds and creating stagnation zones and lee waves (Nakamura, 1982; Grove and Sonu, 1983) Gyosha (1976, Mottet, 1981) concluded that attraction of yellowtail (Seriola quinqueradiata) was almost directly proportional to vertical angle. Fuji (1982) suggested a slop of 90 degrees was best fro yellowtail.

Complexity

Complexity is important for artificial reef success (Ogawa and Takemura, 1966, 1966; Higo and Nagashima, 1978; Higo and Tabata, 1979; Smith et al, 1979; Walton, 1979; Higo et al, 1980). Complexity includes spatial arrangement, number of chambers and openings and the amount of interstitial space. Chang (1976) stated that the most complex reefs were best. The size and number of internal spaces has been correlated with the size and number of certain fishes on artificial reefs (Higo, et al 1980; Buckley, 1982).

Vertical panels on artificial reefs have been found to be much more effective at attracting fishes than skeletal members. Horizontal and diagonal skeletal members are more effective than vertical members (Grove & Sonu, 1983) Attraction probably occurs because these elements create shadows (Grove & Sonu, 1983) which are known to be preferred resting locations (Helfmann, 1979)

Location

Ogawa (1982) and Kuwatani (1982) concluded that the site chosen for an artificial reef was more important than reef design. Oceanographic condition, including wave direction and force, as well as tidal and oceanic currents influence the design success of artificial reefs (Kojima, 1960; Hamashima et al, 1969; Okamoto, 1979; Katoh & Itsou, 1980; McAllister, 1981; Vik, 1982; Grove & Sonu, 1983). Nakamura (1982) suggested that artificial reefs should be placed in current turbulence, areas of upwelling, downwelling, ascending currents and vortex currents.

Grove & Sonu (1983) concluded that reefs were best placed on gently sloping or relatively flat profile areas, in proximity to shoreward encroachments.

Socio-Economics

Ditton (1981) and Graef (1981) concluded that costs of fuel for charter vessels discouraged use of artificial reefs far wary from homeports. Distance traveled away was also directly proportional to required boat size for reasons of safety.

In-Direct Economic and Social Benefits

Documenting only the direct economic benefits ignores indirect benefits; these are not easily translated into dollar values and are often ignored. Social and indirect economic benefits can exceed the actual dollar value. People who never use artificial reefs may receive indirect benefits or may benefit merely because they appreciate the opportunity offered by their presence.

Conclusion

In conclusion, we believe that artificial reefs offer tremendous potential for marine habitat enhancement. We hope that artificial reef technology will eventually be employed within an integrated management strategy for ultimately improving fishery resources.

This article was developed with support from the National Oceanic and Atmospheric Administration. with a grant from the Department of Commerce, USA.

 

Use of Steel Hulled Vessels as Artificial Reefs

Guidelines for Marine Artificial Reef Materials, Gulf States Marine Fisheries Commission, Jan 1997. Produced in co-operation with the US Fish and Wildlife Service, South Carolina Wildlife and Marine Resources Dept, Mississipi Dept of Marine Resources, Louisiana Dept of Wildlife and Fisheries, Alabama Dept of Conservation, Panama City Habitat Conservation Division, Texas Parks and Wildlife Dept, Florida Dept of Environmental Protection, Minerals Management Service. Funded by Federal Aid in Sport Fish Restoration Administrative Funds.

Scrap materials of opportunity account for a large proportion of artificial reef construction materials. Vessels have served as components of most state artificial reef programs. Where available and where depth conditions allow for deployment, vessels remain an important reef material to many reef managers, particularly on the Atlantic Coast (Grove et al 1991). The earliest record of US based intentionally sunken vessels for artificial reefs is 1935 when four vessels were sunk. (Stone 1974). Dozens of steel-hulled vessels sunk along the Atlantic and Gulf Coasts during WWII still provide commercial and recreational fishing opportunities and diving enjoyment more than 50 years later.

Some vessels, barges with open plan or of mixed wood and steel construction, were not designed to withstand heavy sea conditions. Severe storm conditions have caused hull collapse or tearing on this type of construction.

In contrast, a sturdy 110 foot North Atlantic steel trawler, Steanne d'Auray, sunk in 1986 as a reef off Dade County Florida in 68 feet of water, withstood Hurricane Andrew and remained intact. The Doc De Milly, a 287 foot steel freighter in 50 metres of water during the same hurricane suffered no damage. The Shamrock, an 120 foot x/Naval LCI in 40 metres of water also survived unscathed.

Complex vessels are more suitable for artificial reef deployment than those with a lack of structural complexity. Naval frigates or destroyers are an example of high complexity and compartmentalisation. The benefits of retired naval vessels of this type are their inherent strength and ability to withstand extreme sea conditions.

Strength of these vessel is a positive factor, however, as artificial reefs it is their abundance of space variables that is of importance in the enhancement of fisheries. Vertical profiles of ships produce an interruption of bottom currents and create vortex currents (shed eddies), which attract migratory pelagic fishes such as Mackerels, Jacks and Yellowtail.

Vessels can serve as eddy generators and produce modified currents around the vessel which cause low frequency vibrations, which act as stimuli for fish lateral line systems (Lindquist & Pietrafesa, 1989). Wave movement and current are seen as beneficial, generally increasing the density and diversity of marine species on artificial reefs as opposed to areas with no wave action or current.

Shipwrecks have been shown to be able to host large numbers of fishes. An example is a previously un-exploited shipwreck off Australia, which resulted in the harvest of over a tonne of snapper species per day, once it was discovered, until the Government stepped in and designated it a sanctuary. (Branded et al, 1994)

Benefits

Vessels make interesting diving locations and provide a social and economic benefit to the local community through the dive charter and, secondarily, the recreational/charter fishing industry.

Flow-on benefits to other tourism related business increases employment and economic growth in areas like the accommodation, catering, and travel industries.

Vessels have life spans as artificial reefs that can exceed 100 years, depending on vessel type, condition, location of deployment and storm severity.

Vessels, due to high vertical profile, attract both pelagic and demersal fishes. Vertical surfaces produce upwelling conditions, current shadows, along with other current speed and direction alienations which are attractive to schooling forage fishes, which in turn attract species of commercial and recreational importance.

Vessels have a heritage of popularity with divers, fisherman and reef managers. Some opponents of artificial reefs believe that shipwrecks are the only legitimate form of artificial material that should be placed offshore, since they are the only type of man-made structures that typically went to the bottom with or without mans intervention during the millennia of man's use of the sea.

Depending on location, vessels may seasonally hold a large biomass of commercially and recreationally important fish species.

Sinking often creates a media event, providing reef managers with promotional opportunities for their reef of fish enhancement programmes.

Vessels provide diving alternatives to natural reef sites where physical damage to natural reefs through anchor damage, grounding, handling, crawling on, specimen collecting and spear fishing have accelerated deterioration of natural reefs and their associated fauna. Some have been sunk in marine parks/reserves for this reason.

 

This information was compiled by the SinkF69 Charitable Trust during the resource consent process and used as part of its justification for being a member of the Worldwide Ship Reefing Programme.

 

 

  
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