Ask The Experts

Prof. Sebastiano Tusa – Soprintendenza del Mare, Sicily

In which waters do you work and what is your area of specialism?

I work in the Mediterranean, with a particular specialism off Sicily as the Sovrintendente del Mare, but I am working also in Japan. My field is Underwater Cultural Heritage.

Poor preservation of amphoras & anchors on the 4th-century AD Levanzo 1 wreck, Sicily, caused by bottom fishing. Photo: © Sebastiano Tusa.

Poor preservation of amphoras & anchors on the 4th-century AD Levanzo 1 wreck, Sicily, caused by bottom fishing. Photo: © Sebastiano Tusa.

How and when did you first observe bottom damage impacts on underwater heritage?

I cannot remember the first observation of damage because there were many. One of the most recent examples was when I was surveying a deep-sea Roman wreck full of amphorae using a mini submarine at a depth of about 100 metres east of Panarea in the Aeolian Islands, north of Sicily. Almost all of the upper layer of amphora cargo (there were hundreds) were without their rims and necks that had been destroyed and dragged off in nets.

How extensive is bottom fishing in your waters)?

Unfortunately in Sicily bottom fishing dragging nets is widely used, even beyond authorized areas. They also work very close to the coast.

What types of material have come up in trawl nets in the waters where you work?

Generally pottery (amphorae), but also bronze objects (statues and different varieties of tools) and once also ancient scrolls (pergamena) in the Sicily Straits.

What kinds of sites have been affected and how seriously?

Generally in my experience the sites most affected by damage due to trawlers dragging nets are wreck sites. The 94-metre-deep 4th-century AD Levanzo I wreck off northwest Sicily has been badly impacted by dragnet fishing. Artefacts caught, damaged and dumped by ripped nets alongside snagged fishing gear were found underwater on rocky outcrops. The wreck mound had been eroded down to a height of less than 30 centimetres and many areas has been scraped clean of virtually all biological material and loose stones, leaving behind a barren, flat landscape. Long drag marks from trawl gear crisscrossed the seafloor. Fishing off western Sicily similarly disturbed the site of a hugely historically important naval battle fought off the Egadi Islands in 241 BC between Rome and Carthage in the First Punic War. Trawling across the battle site netted two bronze warship rams, a bronze war helmet and numerous amphora fragments.

What is the most important site to be discovered and documented following trawler snags?

In my view the amphora cargo of the Panarea IV wreck dated to the 2nd century AD at about 100 m deep.

Broken amphoras on the 4th-century AD Levanzo 1 wreck, Sicily, caused by bottom fishing. Photo: © Sebastiano Tusa.

Broken amphoras on the 4th-century AD Levanzo 1 wreck, Sicily, caused by bottom fishing. Photo: © Sebastiano Tusa.

Do trawlers avoid wooden shipwreck sites with low reliefs to save nets?

Generally fishermen try to avoid sites, but trawlers do try to pass very close because wrecks are rich in fish and therefore can be abundant fishing grounds.

Do the positives of a trawler finding an ancient or historic shipwreck outweigh the negatives?

I think that if trawlers don’t destroy the archaeological contexts, reports of discoveries are always positive. This is something that we take care to promote. Due to our educational work to convince fishermen to report their discoveries without any legal repercussions, for some years our knowledge of fishing-related finds has increased considerably. The threat level has changed today because there is much more concern about the protection of underwater cultural heritage among fishermen in Sicily due to our strong educational activities. Local fishermen understand the importance of protecting shipwrecks for the benefit of future generations and also for the field of cultural tourism.

Does any governmental legislation or management control the issue?

Of course in Italy and Sicily, particularly, we have strong laws. In Sicily the presence of the Soprintendenza del Mare creates a good management system. In Italy the situation is not properly managed because it has no comparable Soprientendenza del Mare and the protection and management of underwater cultural heritage is run by the terrestrial Soprintendendenze that frequently does not have specialists or the tools to cope with such abundant underwater remains.

What is the future reality for the interaction between bottom fishing and shipwreck preservation?

In my opinion the future must be based on preservation in situ. Of course there could be cases where select and limited excavations are required. In Sicily we already have more than a dozen Underwater Archaeological Parks established and visited so far. Some wrecks, such as the Cala Gadir Punic wreck and the Cala Minnola Roman ship, are protected using remote-access video monitoring (the Sistema Integrato per la Tutela dell’Archeologia Subacquea). Funding must come from the public budget, but also from private sources (especially touristic enterprises or private foundations).

Map of Egadi Punic War battle site sector PW-A, Sicily, showing finds & fishing impacts. Photo: © Sebastiano Tusa.

Map of Egadi Punic War battle site sector PW-A, Sicily, showing finds & fishing impacts. Photo: © Sebastiano Tusa.

What political or technological measures could stabilise or improve the issue by minimising impacts?

Politically I think that education is the basis to counter the destruction of underwater cultural heritage. Technologically in some cases it is necessary to place on the seabed near wrecks or other sunken sites or objects devices that can ensure avoidance of dragging activities, such as concrete blocks embedded with iron spikes.

What can be done to better help fishermen maintain stock catches and minimise threats to their equipment, while preserving important wrecks?

First of all: educational programmes. Secondly: increase the number of marine protected areas. Thirdly: educate the customer to eat all varieties of fish and not only tuna, swordfish, shrimp and sole. I am optimistic about the future.

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Dr Carlo Beltrame – Lecturer of Maritime Archaeology & Methodologies of Archaeological Research, Università Ca’ Foscari, Venice

Dr Carlo Beltrame, Venice

Dr Carlo Beltrame, Venice

In which waters do you work & what is your area of specialism?

I have worked in the Italian Northern Adriatic coast for over 25 years. These days I focus more on the Croatian Southern Adriatic coast and in Sicily. I have worked on shipwrecks from the Greek period up to the 19th century.

How & when did you first see bottom damage impacts on underwater heritage?

I observed the impacts of bottom fishing for the first time on the Roman shipwreck of Grado (Gorizia) with a cargo of amphoras, then on the Roman shipwreck of Caorle (Venezia), on the 1812 Napoleonic shipwreck of the Mercurio (Lignano-Udine) and on the medieval galley of San Marco in Boccalama (Venice).

How extensive is bottom fishing in your waters?

We can say that there is no square metre of sea that has not been trawled extensively in the Italian Northern Adriatic coast. The rapido trawler mainly catches scallops and sole in the Gulf of Venice using a dredge rake equipped with a toothed beam, typically 3 metres wide. Each dredge weighs around 170 kilograms and is fitted with some 32 fixed teeth. Up to eight dredges may be operated by a single vessel. Fishing boats known locally as turbosoffianti, using suction dredges in sandy and muddy sea bottoms to collect clams, operate closer to the shore in more limited areas. Both fishing methods have a devastating impact on submarine archaeological deposits, causing damage and dislodging.

What types of remains have come up in trawl nets in the waters where you work?

The biggest item was a carronade weighing 1,000 kilograms from the Napoleonic shipwreck of the Mercurio (1812). This was the most important site found so far ‘thanks’ to the impact of a fishing boat. Other items recovered by nets come from both ancient and modern shipwrecks, such as amphoras, pottery, Roman lead stocks and Byzantine iron anchors. Other than the case of the Mercurio, generally fishermen do not report discoveries to authorities.

An iron carronade from the wreck of the Napoleonic ship Mercurio, Lignano, Italy, lost 1812, after recovery in a fishing net. Photo: © Carlo Beltrame.

An iron carronade from the wreck of the Napoleonic ship Mercurio, Lignano, Italy, lost 1812, after recovery in a fishing net. Photo: © Carlo Beltrame.

What kinds of sites have been affected & how seriously?

Shipwrecks have been heavily impacted, especially in the upper level. On the Roman shipwreck of Caorle, the protective cover of metal nets was removed by the passage of trawlers.

Do trawlers avoid wooden wrecks with low reliefs to save nets?

Usually fishermen know where the shipwrecks are located (they call them “presure” in Italian, so something which “takes” the net) and tend to avoid them to protect their nets.

Do the positives of a trawler finding a shipwreck outweigh the negatives in terms of knowledge & preservation?

In the case of the Mercurio the positives outweighed the negatives. The other cases I know are recoveries of single finds, which have been extracted from their original archaeological context. The Grado and Caorle Roman shipwrecks were impacted by nets after being discovered by divers.

What management controls have been put in place & are they effective?

On the Caorle shipwreck authorities tried to cover the site, but the protective metal net was removed by trawler action. The only effective solution is to protect a site with large stone or concrete blocks all around the wreck. This technique was used on the Grado 1 Roman shipwreck. The threat level from bottom fishing has not changed over time.

Does any governmental legislation or management control the issue?

Yes, navigation over shipwreck sites is forbidden, but this solution has no serious effect on prevention.

Amphora cargo on the Roman wreck at Grado, its necks cut off by trawler net gear. Photo: © Carlo Beltrame.

Amphora cargo on the Roman wreck at Grado, its necks cut off by trawler net gear. Photo: © Carlo Beltrame.

What is the future reality for bottom fishing & shipwreck preservation?

There are no dedicated funds for this problem. Sometime excavations are organized and site protection using metal nets are attempted.

What political or technological measures could stabilise or improve the issue?

There is currently no discussion of this problem. I think that the only solution is to protect a site by surrounding it with large blocks of concrete. Metal nets or cages could be another complementary solution to protect wreck contents from looters.

What can be done to better help fishermen maintain stock catches & minimise threats to their equipment, while preserving important wrecks?

Inform fishermen about the location of shipwrecks, offer better dissemination and education of the results of research to prove the social utility of archaeology, but in the same time protecting a site with dissuasive techniques.

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Dr Michael Flecker – Manager Director of Maritime Explorations, Singapore; Associate Fellow, Singapore Institute of Southeast Asian Studies

In which waters do you work & what is your area of specialism?

As a maritime archaeologist I have been working throughout Southeast Asia for nearly 30 years on sites dating from the 9th to the 20th century. Specifically I have worked in Indonesia, Malaysia, the Philippines, Vietnam, the Gulf of Thailand, and within disputed areas of the South China Sea.

How & when did you first see bottom damage impacts on underwater heritage?

I excavated two wrecks in Vietnam and one in Thailand during the 1990s, namely the Vung Tau Wreck (c. 1690), the Binh Thuan Wreck (c. 1608) and the Klang Ao Wreck (early 16th century). They were all discovered by trawlers, but the damage was minimal. This is probably because the trawlers were small and the wreck mounds were well covered by sediments.

Dishes from the Binh Thuan wreck, c. 1608, Vietnam, stowed sidewise; exposed edges broken off. Dishes in the centre are post-excavation (not in situ). Photo: © Michael Flecker.

Dishes from the Binh Thuan wreck, c. 1608, Vietnam, stowed sidewise; exposed edges broken off. Dishes in the centre are post-excavation (not in situ). Photo: © Michael Flecker.

How extensive is bottom fishing in your waters?

On side-scan sonar records from the east coast of Peninsula Malaysia the trawl coverage is total in some areas. The parallel scars left by otter boards criss-cross the seabed in a dense pattern. All steel wrecks and recent wooden wrecks off the east coast are covered in trawl nets.

Editor’s Note: Malaysia has banned trawlers from within 30 nautical miles of shore, so fleets largely work increasingly further offshore. Indonesia has banned trawling by foreign vessels, but authorities claim foreign fishing boats operating illegally within the country’s waters cost the local fishing industry $2 billion annually. Local cucumber fishermen find many important wrecks inshore. See: Nuruddin, A.A. and Isa, S.M. (2013), ‘Trawl Fisheries in Malaysia – Issues, Challenges and Mitigating Measures’, Presentation to the APFIC Regional Expert Workshop on Tropical Trawl Fishery Management, Phuket, Thailand, 30 September to 4 October.

What types of remains have come up in trawl nets in the waters where you work?

Reported finds in trawl nets are invariably ceramics. Robust stoneware storage jars originally stowed on deck or above other cargo tend to be the first indication of a new wreck find off Malaysia.

What kinds of sites have been affected & how seriously?

From my personal experience ceramic cargoes suffer most. Wooden hull remains tend to be buried. Large iron concretions can withstand small trawl nets, such as those generally used in Malaysia, but not the large Thai trawl nets. Thai trawlers are now operating throughout Southeast Asia under license. A colleague, Sten Sjostrand, found the Desaru shipwreck, located 2 nautical miles off southern peninsular Malaysia, littered with broken planks and misplaced bulkhead frames.

 What is the most important sites discovered & documented following trawler snags?

By me personally, the Vung Tau wreck (c. 1690, Vietnam), the Binh Thuan wreck (c. 1608, Vietnam), and the Klang Ao wreck (early 16th century, Thailand). All were discovered by trawler snags. The Binh Thuan wreck contained stacks of Chinese porcelain dishes partially buried in sediment. Several of these stacks had the exposed part of the dishes smashed off.

Chinese porcelain smashed by trawl nets on the Wanli shipwreck, c. 1625, Malaysia. Photo: © Sten Sjostrand.

Chinese porcelain smashed by trawl nets on the Wanli shipwreck, c. 1625, Malaysia. Photo: © Sten Sjostrand.

Do trawlers avoid wooden wrecks with low reliefs to save nets?

Fishermen only avoid steel wrecks. In some cases they relocate wrecks with ceramic cargoes by deliberately trawling over them. In the case of the Hoi An Wreck in Vietnam, steel rakes were devised to recover ceramics as the wreck was too deep for local divers. Fishermen do not report discoveries to authorities.

Do the positives of a trawler finding a shipwreck outweigh the negatives in terms of knowledge & preservation?

When most discoveries were made by small trawlers, the positives did outweigh the negatives. As there are no archives containing records of Asian shipwrecks, trawling has brought to light wrecks that would not otherwise have been found. But large trawlers, such as those frequenting the seas now, destroy the wrecks they find.

What is the future reality for bottom fishing & shipwreck preservation?

There is no interaction whatsoever, which is the main reason in situ preservation is completely unrealistic in a Southeast Asian context. The threat level continues to increase today, due to both increasing fishing trawler boat sizes and numbers. No effective government mitigation or management controls have been put in place. There is political indifference to historical shipwrecks throughout most of Southeast Asia. Impacts are not on the political radar.

What can be done to better help fishermen maintain stock catches & minimise threats to their equipment, while preserving important wrecks?

The issue is dwindling catches due to overfishing. The answer has been to bring in larger trawlers which can operate in deeper waters. The threat to their equipment only comes from steel wrecks, and by now they have probably plotted most of those on their chart plotters.

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Nico Brinck – Ordnance Specialist, Terschelling, Holland

In which waters do you work & what is your area of specialism?

I have been working along the Dutch coast of the North Sea for 25 years, specialising in maritime archaeology, and have recorded 77 iron and bronze cannon landed in Holland, Belgium and Denmark by trawlers working in the North Sea.

A gun from the German submarine U-61, sunk 1918. Knocked off the wreck by a North Sea trawler & recovered by Dutch divers. Photo: © Nico Brinck.

A gun from the German submarine U-61, sunk 1918. Knocked off the wreck by a North Sea trawler & recovered by Dutch divers. Photo: © Nico Brinck.

How & when did you first see bottom damage impacts on underwater heritage?

My interest in diving and underwater archaeology started in 1990, and during the early dives fishing nets were seen on wrecks and enormous damage caused by flattening operations (using explosives) by the government to guarantee a desired depth in North Sea shipping channels and some coastal waters.

How extensive is bottom fishing in your waters?

Shrimpers and fishing trawlers work extensively in our waters. Dredging is monitored by the government using a ‘black box’ onboard ships. Trawling is not monitored in this way.

What types of remains have come up in trawl nets in the waters where you work?

In the last two decades trawl nets have dragged up torpedoes, parts of submarine hulls, anchors, mines, airplane bombs, frames, planks and spars from wooden ships, historic and early modern iron and bronze cannon, airplane parts and ammunition. On the positive side tons of plastic have also been stripped from the sea bottom by fishermen and brought ashore.

A Swedish iron cannon & carriage dated 1696, covered in net, & trawled up off Holland. Photo: © Nico Brinck.

A Swedish iron cannon & carriage dated 1696, covered in net, & trawled up off Holland. Photo: © Nico Brinck.

What kinds of sites have been affected & how seriously?

Mainly 16th to 18th-century wooden shipwrecks. It is difficult to determine the seriousness of the affects due to a lack of underwater survey data. All you mostly see is the end product: finds landed ashore from a largely unknown location. In many cases, however, heavy lost fishing nets protect sites from erosion. Heritage divers now use this method to protect old wooden wreck sites.

What is the most important site discovered & documented following trawler snags?

The Eendracht was a flagship of the Dutch confederate navy lost in the Battle of Lowestoft on 13 June 1665, the first battle of the Second Anglo-Dutch War. Only five people from a crew of 409 survived. The wreck has still not been documented. At least 15 bronze cannon have been landed by trawlers from this wreck, half of them unreported to heritage officials. The site is located in the middle of a deep-water anchorage, so huge anchors are also dropped on the unfortunate site.

Stern of the English submarine HMS E-3, lost in 1914. Caught in a North Sea trawler net in 1990. Photo: © Nico Brinck.

Stern of the English submarine HMS E-3, lost in 1914. Caught in a North Sea trawler net in 1990. Photo: © Nico Brinck.

Do trawlers avoid wooden wrecks with low reliefs to save nets?

If a position is known a trawler will avoid any obstruction on the seafloor to save their net. Only the Eendracht site is currently known to have been fished through a few times on purpose with the hope of catching a bronze cannon.

Do the positives of a trawler finding a shipwreck outweigh the negatives in terms of knowledge & preservation?

Yes, as long as the find is reported. A historic wreck in the North Sea is unlikely to be documented nowadays, let alone preserved for economic reasons.

Has the threat level changed over time?

Yes, especially in the last five years. During the last 15 years enormous changes have taken place within the Dutch bottom trawler fleet. Its size has been reduced by some 50% (due to the general economic situation) and in the last few years electric pulse fishing has been introduced that hardly touches the seafloor (invented by fishermen to reduce ship fuel costs and increase yields). Both changes enhance the sustainability of fishing and cause less bottom damage and air pollution.

What is the future reality for bottom fishing & shipwreck preservation?

I see no change for the near future. Fishermen will continue to try to avoid damage to their gear and the government will not spend any money on the protection of wrecks. No governmental legislation or management controls the issue.

Wooden ship’s frame snagged in a Dutch coastal North Sea shrimper net & discarded on the dock in Terschelling, Holland. Photo: © Nico Brinck.

Wooden ship’s frame snagged in a Dutch coastal North Sea shrimper net & discarded on the dock in Terschelling, Holland. Photo: © Nico Brinck.

What political or technological measures could stabilise or improve the issue?

The issue will have to be high on the international (European) political agenda, which will not be the case before the current immigration problem, among others, has been resolved. Technologically electric pulse fishing is a major option for reducing impacts due to the much lighter bottom gear used.

What can be done to better help fishermen maintain stock catches & minimise threats to their equipment, while preserving important wrecks?

Place a windmill or buoy next to a wreck to make trawlers avoid the area.

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