2.1 The History of Trawling

Bottom trawling developed from the practice of fishing with a net or long lines, but that older style was able to be more controlled and discriminate in its catch. With bottom trawling, nets are weighted to keep them low along the seafloor and a large beam on deck spreads nets wide to increase catch. Marine biologists and environmentalists have been concerned about trawling since it began. As far back as 1376, the English parliament highlighted the destructive nature of the practice to fish populations and habitats, noting that it ‘runs so heavily and hardly over the ground when fishing that it destroys the flowers of the land’ and takes so many fish ‘to the great damage of the commons and the destruction of the fisheries’ (Petition by the Commons to King Edward III, 1376 seen in Bolster, 2012). This first known mention of trawling calls for the removal of the practice and yet the activity endures. Trawling in Europe continued sporadically through the medieval and early modern periods using mainly the beam trawl method until the early nineteenth century when the industrial revolution pushed the technology further.

By 1840, fishers using sail power were already noticing depleted stocks, so changes developed out of a necessity to compensate for a declining catch. The introduction of steam-powered vessels ushered in a new modern era of commercial fishing (Roberts, 2012). The first purpose-built British steam trawling vessels were completed in 1881 and could gather four times more fish per catch than a sailing vessel (Bolster, 2012). Steam powered vessels were not as limited by weather and had the strength to power nets with chain reinforcements on the seafloor. By the end of the nineteenth century, this enabled the transition to the otter trawl, where two ‘doors’ are used to open the nets and accommodating larger nets (see Fig. 2.1 for a comparison of the methods) (National Research Council, NRC, 2002). Net size was no longer limited by the length of the vessel or the wooden beam, but by the power of the tow vessel (Atkinson, 2012). Beam trawling remained popular in some European countries, though and while otter trawl use increased, beam trawls were never fully abandoned (Ferrari, 1995).

Fig. 2.1
2 illustrations of 2 trawlers with different trawls. Top, there is a trawler with 2 beam trawls. Bottom, there is a trawler with an otter trawl.

A beam trawl (top) and otter trawl (bottom). (Source: Ecomare/Oscar Bos, licensed under the Creative Commons Attribution-Share Alike 4.0 International)

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In the United States, scientists initially welcomed trawling as it gathered more fish to study and, since they believed the sea to be limitless, they were unconcerned about the practice (Bolster, 2012). Beam trawlers were introduced just before the twentieth century in Cape Cod and soon gasoline powered engines revolutionised the industry (NRC, 2002). In 1912, Congress appointed funds to the Bureau of Fisheries to investigate ‘whether or not this method of fishing is destructive to the fish species or is otherwise harmful’ (Bureau of Fisheries, 1914 and quoted in Bolster, 2012, p. 258). Two and a half years later, the report was published and, in an effort to prevent monopolies, did not recommend the prohibition of the practice and opened the door to large-scale otter trawling in ‘certain definite banks and grounds’, though it admitted ‘While the facts before us show no proof or presumption of any depletion of the fisheries on the banks frequented by American otter trawlers… it is possible that the seeds of damage already have been sown and that their fruits may appear in the future’ (Bureau of Fisheries, 1914 and quoted in Bolster, 2012, p. 258).

Arguably the most detrimental technological advance came after World War II. Factory-sized, freezer-equipped trawlers were introduced that had stern ramps to accommodate larger nets, quick freeze facilities and storage, and fishmeal processing machines onboard. The increase in cod catches off Newfoundland are a good example to illustrate the effects. From 1875 to 1955, steam and gasoline power caused catches to rise from 160,000 to 300,000 metric tons. New factory trawlers brought in 500,000 tons in 1960 and 800,000 tons in 1967. These examples also illustrate how quickly stocks can become depleted, however, because over the next 9 years, catches fell to 150,000 tons (Bolster, 2012).

Trawling spread to greater depths, spearheaded by the Soviet Union, and it quickly grew into a global industry. Previously, the high seas were regarded as too dangerous and not economically worth fishing, but the 1950s and 1960s saw the rise of echosounders and increased access to areas beyond the reach of shallow trawls. But these new fishing grounds often had rough seafloors that shredded the nets. In response, a technology was developed to shield the nets from obstructions, but which also significantly increased the destructive power of trawls. ‘Rockhopper gears’, measuring up to 1 m in diameter and weighing hundreds of kilograms, are massive steel rubber rollers attached to ground ropes on trawl nets, enabling the nets to roll over obstacles, but which increase the damage to the seabed (He et al., 2021; Watling & Norse, 1998). ‘Tickler chains’ would also be added ahead of the ground rope to scrape the seafloor and drum up catch (Jones, 1992; Watling & Norse, 1998) (Figs. 2.2 and 2.3).

Fig. 2.2
A 3 d model of a rockhopper gear with attached 4 steel rubber rollers. On the right, an illustration depicts a side view of a trawling net.

Rockhopper gear (left) and position on a trawling net (right). (Source Seafish: www.seafish.org/ reprinted with permission)

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Fig. 2.3
A 3 D model of a trawling net. It features curved tickler chains with both ends attached to a bar in the front.

Trawling net with tickler chains towed ahead of net. (Source Seafish: www.seafish.org/ reprinted with permission)

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Commercial fishers now had the technology to send their boats out for longer, fish further away, and fish faster with larger nets (NRC, 2002). Eastern European nations took these to a new level creating ‘floating towns built for the sole purpose of processing marine life into food’ (Roberts, 2008, p. 189). Biologically productive deep seamounts became the new targets and using sonar, vessels could trawl through a large group of fish taking in 50–60 tonnes in a few minutes (Roberts, 2008).

Today, trawling has grown to previously unimaginable rates. The nets used, some measuring more than 4 stories tall, cut paths through the seafloor at least 100 m wide, pulling in fish at unsustainable rates—a recent FAO report shows that one-third of global fish stocks are overfished (FAO, 2020). A study by Villy Christensen and his team estimated that today’s fish stocks are a tenth of what they were in 1900, and two thirds of that destruction comes from 1950 onwards (Christensen et al., 2003). But, as Callum Roberts shows, by 1900 stocks were already heavily decreased so the real number is more likely less than 5% of natural levels (Roberts, 2008).

Many nets are made of synthetic materials which do not break easily when snagged, allowing for higher powered vessels (Brennan, 2016). These nets also make up the largest portion of marine debris and plastic pollution in the ocean (Napper et al., 2022). With modern improved gear and electronics, vessels use sonar to target schools of fish and specific bathymetric areas, allowing for fishing over targeted areas of seabed, and drag their nets over rougher seafloor than before, decimating fish populations to a greater extent (Pederson & Dorsey, 1997).

2.1.1 Dredging

Trawling is not the only method of bottom fishing, and in many cases the impacts of dredging on the seabed are just as harmful as bottom trawling. Dredging and trawling are grouped together as fishing methods known as ‘mobile fishing gear’ and though bottom trawling is the focus of this book, dredging will be briefly summarised. A dredge is a cage-like contraption, sometimes with a scraper blade or teeth on the lower part, which is towed behind the vessel to excavate organisms out of substrate and capture them (He et al., 2021). Molluscs, particularly mussels, oysters, scallops, and clams, are the most targeted species. Towed dredges or mechanised (hydraulic) dredges are used, and these methods have similar environmental impacts to trawling with both long- and short-term results including the elimination of natural bottom features and flattening of substrate, shift in surface sediment, burying of organisms, reduction in seagrass, and reduction in species abundance (Caddy, 1973; Currie & Parry, 1996; Hall et al., 1990; Hall-Spencer, 2000; Kaiser, 1997). Dredges also carve deeper furrows in the seabed than trawls, as their target species are within the sediment rather than on top of it (Fig. 2.4).

Fig. 2.4
A 3 D model of a scallop dredge is on the left. On the right, there is a 3 D illustration represents a trawler with 8 scallop dredges aligned in a row.

Scallop dredge (left) and row of scallop dredges (right). (Source Seafish: www.seafish.org/ reprinted with permission)

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The historical origins of dredging are unknown but seem to predate trawling in some areas (Ferrari, 1995). The impact on UCH is similar to bottom trawling and many surveys and research mention dredging activity in the area (see Steinmetz’s thesis examining trawling and dredging impacts on shipwrecks in the Mid-Atlantic 2010). For example, off the Isle of Mull, Scotland, the wreck of the Swedish general-cargo steamship SS Hispania (built 1912) has been salvaged and visited by divers since the 1950s. In 1999, a scallop dredger caught on the vessel and the scrapes made by the gear damaged the hull as well as laying a mast on its side (Robertson, 2007). Additional surveys in 2001 showed further dredge damage. Dredging also poses a significant risk to UCH found in the waters of the Arctic (Ragnarsson et al., 2006). This is especially worrying to archaeologists because of the high level of preservation exhibited by shipwrecks in this location (Nœvstad, 2006). Like in the deep-sea, shipwrecks that have been undiscovered and well-preserved are damaged by fishing activities before they can be studied. For example, scallop dredgers near Spitsbergen have pulled anchors, ship timbers, and ceramics from the ocean and with only a few incidents actually reported, it is difficult to know the full extent of damage (Nœvstad, 2006). Dredge impacts have also been documented on steel hulled wrecks, such as that of the oil tanker Coimbra, sunk off Long Island in 1942 (Brennan et al., 2023).

2.2 The Ecological Impact

Trawling has been shown to harm sea life and the sea floor by reducing topography, compression and resuspension of sediments, decreasing complexity, and causing both physical and chemical damage to the ecosystem. Trawling can penetrate sediment 20 cm or more and cut scars into the ground 1–3 m wide, causing advection and reoxygenation of the sediment strata (Friedlander et al., 1999). The otter trawls can rework the seafloor, sometimes moving boulders that weigh more than 30 tonnes (Atkinson, 2012). This decreases the roughness, and thus the complexity of the bottom, by smoothing the bottom structures and removing bottom fauna (Pederson & Dorsey, 1997; Brennan et al., 2012). Structures like ripples, mesophotic reefs, and other soft suberate habitats are destroyed (Brennan et al., 2016).

Coastal seas are some of the most ecologically productive areas and areas of heavy trawling. Marine ecologist Callum Roberts writes that ‘the spread of trawling caused the greatest human transformation of marine habitats’ (Roberts, 2008, p. 156). Seas have shifted from complicated, productive, rich environments to expanses of flat gravel and mud as continuous trawling in these fishing grounds has eliminated entire habitats. In the Wadden Sea, for example, reefs thousands of years old are gone and so are the bottom habitats, and fauna reliant on them (e.g., oyster reefs, eelgrass, seaweed) (Lotze, 2005).

Trawling also resuspends sediments, which is detrimental to the sedimentary and chemical processes occurring on the seafloor (Brennan et al., 2016). The nutrients and toxins within the sediment can alter the chemical composition of the habitat, which also can increase metal corrosion and organic material deterioration on shipwrecks (Duplisea et al., 2001; Mayer et al., 1991; Pilskaln et al., 1998). The resuspension and reoxygenation of the sediments disturb the anoxic bacterial processes occurring below the sediment-water interface and diminishes the benthic role of bacterial decomposition of organic matter within the surface sediments.

A more obvious impact of trawling is the decimation of fish populations. Intensive fishing alters the balance between the young and old of a population and when the balance is off, populations cannot recover. Areas that have been heavily trawled become dominated by small-bodied species that can colonise and recover quickly, displacing larger long-lived species (Olsgard et al., 2008). These smaller benthic species can withstand the mortality imposed by trawling and then benefit from the reduced competition in the ecosystem (Jennings et al., 2001).

The continuous intensive overfishing of target species makes it nearly impossible for populations to recover and reduces the ability for the fishery to be sustainable. This is shown by an example that during WWI and WWII, as the fishers and their boats were taken into the war services, some fish populations rebounded. In the North Sea, species benefited from the break in exploitation and when fishing resumed in peacetime, there were larger catches than previous (Beare et al., 2010; Holm, 2012). Inevitably, the populations crashed again, and fishers sought new grounds.

The effects of trawling in deep water are more pronounced. Fish species in the deep ocean have lower growth rates and populations take longer to recover than in coastal waters. Early 1980s catches in the deep waters of the Gulf of Maine were twice as high as the levels that could be sustainable and by the mid-1980s, 60–80% of species were taken (Dobbs, 2000). Various estimates of the cod population in this area today put the numbers around one third of one percent of what it should be (Rose, 2004). Trawlers also commonly target deep seamounts, which function as ‘refuelling stops’ for many fish species in the open ocean. The populations here, and the benthic ecosystems, have been decimated by continuous overfishing.

Trawling has not necessarily helped fishers and the global fish market either. Intensive trawling, through seafloor destruction and population decimations, undermines food webs that support the fish species we seek to catch for consumption. Roberts estimates that fishers today pull in just 6% of what they did about a century ago, showing that there are literally fewer fish in the sea because of human practices (Roberts, 2012). A World Bank report, The Sunken Billions, noted that if we fished less, the major fish stocks globally would begin to produce 40% more in a few years and maybe 60% in European waters (Willmann & Kelleher, 2009). But fishing quotas set by EU policy leaders still tend to range one third higher than the safe catch levels recommended by their own scientists.

2.3 Regional Case Studies

Due to a number of factors, including accessibility and research conducted, not every region of the ocean could be covered as a case study in this volume. Some of the key findings and notable research are summarised below.

2.3.1 Pacific

The issue of heritage destruction by trawling is important to the Asia-Pacific Region because traditionally, trawling studies with UCH have focused on European and North American waters, even though roughly 50% (over the last decade of available data) of all bottom trawled fish come from the continental shelf/EEZs of Asian nations or the foreign fleets of Asian countries (Steadman et al., 2021, p. 5). Many wrecks in the Pacific region lie in areas of heavy trawling activity and the wreck timbers have already been damaged. For example, the Longquan Wreck is a fifteenth-century wreck with timbers standing nearly two metres tall in the deep water off the coast of Malaysia. It was originally found with a fairly intact cargo but was later found to have been flattened by Thai trawling vessels (Flecker, 2002). This was also the case with the sixteenth-century Singtai Wreck (Flecker, 2002).

Three kilometres west of Ko Si Chang, Thailand, the Chang I wreck was found in 1982 during the excavation of a nearby site (Green et al., 1986). The site consisted of scattered ceramic sherds and some exposed hull timbers. The wreck was visited in subsequent seasons and archaeological survey markers were left behind. By the time archaeologists revisited the site in 1985, the markers from 1983 were missing, likely sheared off by trawl gear given the trawling activity in the area and presence of trawl nets hung up on portions of the site (Green et al., 1986). The excavators also noted there were no complete ceramic vessels found, and ‘thought that the trawlers have scoured the surface of the site and caused material to be damaged or moved off the site’ (Green et al., 1986, p. 116).

In Vietnam, less than two miles from the southern tip of Phu Quoc Island, a team of archaeologists were invited by the Vietnam Salvage Company in 1991 to examine a newly discovered shipwreck, later dated to the fourteenth or early fifteenth century (Blake & Flecker, 1994). Much of the hull remained intact and the vessel was surrounded by a large amount of ceramic, nearly all broken. The archaeologists, Warren Blake and Michael Flecker, noted that ‘trawling and the use of explosives, both common fishing methods in the area, could explain the widespread field of broken pottery around the hull’ (Blake & Flecker, 1994, p. 73). Additionally, off the coast of NSW Australia, many wrecks have been impacted by scallop dredgers including the City of Launceston, Euralba, Eleutheria, the Isis, and the Lady Darling (Derksen & Venturoni, 2011).

2.3.1.1 West Africa

The waters around West Africa present an interesting case of fisheries management, foreign exploitation of local livelihoods, and an illustration of the lack of archaeological work in the developing world. Since the 1950s, West Africa’s fisheries have been targeted by foreign nations including Russia, Europe, and most recently China (Steadman et al. 2021). In the 1980s, as their own fish stocks showed signs of depletion, China developed a fleet to fish in foreign waters and now deploys trawlers in the EEZs of nearly every country in West Africa. The technologically superior foreign vessels can catch five times as much in one day as a small village fleet gather in one year (Wester, 2023).

This exploitation by foreign vessels has led to conflict between the industrial vessels and local small-scale boats where more than 250 of West African fishers die each year because of collisions or incidents with trawling vessels (Steadman et al. 2021). Journalists have investigated the issue (e.g., Wester, 2023; Jacobs, 2017) and highlight many cases of witnessed corruption within the African fishery inspectors and port authorities. Illegal fishing is also rampant with many vessels catching more than their quotas or switching off their vessel tracking systems (Welch et al., 2022).

The risks to UCH are understudied in this part of the ocean as well. Maritime archaeology in Africa is less common when compared with places like the Mediterranean, European waters, or North America. For example, Gregory Cook, Rachel Horlings, and Andrew Pietruszka’s work (Cook, 2012; Cook et al., 2016; Horlings & Cook, 2017) off the coast near Elmina Castle, Ghana was the first in the area and other major maritime archaeology work includes work in Senegal (Guérout, 1996) and Cape Verde (Smith, 2002). The potential that maritime archaeology in West Africa is immense and could be impacted by trawling if it has not been already (Fig. 2.5).

Fig. 2.5
Ascreenggrab of an interface represents the map of coasts of Africa. It indicates data from prehistory, classical era, middle ages, and modern times for wrecking or archaeological confirmation of a vessel.

An example of shipwrecks off the coast of Africa. This only shows Dutch vessels with historic evidence for wrecking or archaeological confirmation of a vessel covering centuries of history. Vessels like these ones are at risk from trawling. (Source: Maritime Stepping Stones (MaSS), licensed under the Creative Commons Attribution-ShareAlike license (CC BY-SA))

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2.3.2 Arctic

UCH in the Arctic is also at risk from mobile fishing gear. A report commissioned by the Nordic Council of Ministers (Ragnarsson et al., 2006) gives an excellent overview of both the ecological damage as well as destruction of UCH presented by Dag Nœvstad. For example, when a vessel was doing maintenance work on an oil platform in the North Sea, an 11-m-long, 2-ton, piece of a ship’s keel was found, tangled in a net. It had, seemingly, been dragged by a trawling vessel until being brought to the oil platform near Norway (Nœvstad, 2006). Plenty of prehistoric material, including Stone Age tools, have also been trapped in fishing gear and removed from their contexts (Nœvstad, 2006). Parts of wooden ships dating back to the sixteenth century have also been brought up by trawlers near Greenland (Nœvstad, 2006).

2.3.3 Prehistoric Material

It is not just shipwrecks being destroyed. Among the sites worst affected by trawlers is Doggerland, a 30,000-km2 area inhabited during the Mesolithic period (8000 years ago), which is now under the waters of the North Sea. Hundreds of stone tools and bones have been dragged up over the centuries as it has been continually targeted by trawlers (Louwe Kooijmans, 1970; Ward & Larcombe, 2008; Mol et al., 2006). This area is a valuable example of a site that is both a paleo-seascape as well as a site of past human inhabitation and rising sea levels have put many other prehistoric landscapes under coastal waters.

Also in the North Sea, near Brown Bank, Dutch fishers found items dating to 7200–6000 BC and near Colijnsplaat, Netherlands, when Roman alter stones were dragged up (Louwe Kooijmans, 1970; Hassal, 1978). Even a Neanderthal skull fragment has been found in this area (Hublin et al., 2009) and many more examples of prehistoric material, such as mammoth bone, have been brought up by North Sea fishers since at least 1874 (Glimmerveen et al., 2008). English fishers have pulled material as well, with notable studies in tools taken by oyster dredgers in Solent, near the Isle of Wight (Momber et al., 2011) and overall interactions between fishing and the North Sea’s historic environment (Firth et al., 2013).

There are many examples of this in North America too. As a result of deglaciation and isostatic uplift, many indigenous sites are now covered by water, many are located kilometres offshore. For example, in 1988 a hydraulic clam dredge on Maryland’s eastern shore of the Chesapeake found the Nicolas Point site (Lowery & Martin, 2009). The dredges in the area act as a ‘backhoe’ and ‘virtually every clam dredger has discovered prehistoric artefacts while dredging’ (Lowery & Martin, 2009, p. 160). At Nicolas Point, this included a rare Archaic-age burial feature. Additionally, fishers off the coast of Maine have found 9000-year-old tools, which prompted an Institute of Maritime History survey sponsored by a NOAA grant.Footnote 1

2.4 Management of Trawling and Fishery Sustainability

Fisheries require management at multiple levels and bottom trawling is no different. Within a nation’s Exclusive Economic Zone (200 nautical miles from the shoreline) the coastal state has the rights to fish and responsibility for management. Domestic regulatory framework is the primary way this is done. Within the European Union (EU), the Common Fisheries Policy (CFP) is in place and is managed by the European Commission. At an international level, in the UN fisheries are managed by the Food and Agriculture Organisation (FAO) and Straddling Fish Stocks Agreement (the United National Fish Stock Agreement adopted 1995 and in force in 2001) regulates fish stocks which pass through multiple countries’ EEZs. Management and regulation of fisheries continues to advance. As European waters are some most heavily trawled, in 2019, the European Commission implemented ‘a global management strategy for the whole western Mediterranean’ although each country still manages its own waters and governs which areas or seasons bottom fishing is restricted (Vigo et al., 2023, p. 2). In other waters, however, such as southeast Asia, trawling remains largely unregulated and non-selective (Hilborn et al., 2023).

While bottom trawling is the largest type of physical disturbance by humans to the marine environment, it is also an essential component of the global food supply (Hiddink et al., 2020). The ‘magnitude of the effect of the trawl disturbance on benthic communities depends on the frequency of trawling, the impact per trawl pass, and the individual recovery rates of biota exposed to trawling’ (Hilborn et al., 2023, p. 568; Hiddink et al., 2017). However, the idea that trawling needs to be banned entirely and is unsustainable is not accurate. Effective management can lead to sustainable fisheries. While many fish stocks worldwide are overexploited, this is a ‘failure of fisheries management to control fishing pressure rather than a direct consequence of the fishing gear used’ (Hilborn et al., 2023, p. 1568). In essence, bottom trawling in some form is necessary, as it provides a form of food production, which in fact has been shown to have a lesser footprint than other forms, such as aquaculture, crops, and livestock (Hilborn et al., 2023). That having been said, bottom trawls are the least fuel-efficient types of fishing gear, but allowing fish stocks to rebound and be fished sustainably would minimise the distance fishing vessels need to travel to find new grounds.

In addition to fisheries management and sustainability, another recent concern has been the contribution of bottom trawl fishing operations to carbon emissions. One of the major impacts to the seabed of mobile fishing gear is the resuspension of the top strata of sediments that plows through benthic communities and alters biogeochemical processes at the sediment-water interface. The concern is that the resuspension of sediments allows for more mixing of the sediments with seawater and allow remineralisation of carbon initially buried in the seabed to be exposed again to oxygen and prevent its sequestration (Zhang et al., 2023). Initially proposed by Sala et al. (2022), the idea is controversial, as other scholars suggest the increase in nutrients from the resuspended sediments that thereby increase primary production may offset the influx of carbon. However, not to diminish the profound impact of trawling to the marine environment, an evaluation of the carbon flux from sediments due to trawling indicates that only a fraction of sequestered carbon would impact atmospheric CO2 levels and that there is little evidence trawling has contributed directly to greenhouse gas emissions (Hilborn et al., 2023).

Nevertheless, bottom trawling must be regulated to maintain sustainable fisheries worldwide, which is a trade-off between the detrimental environmental effects with food scarcity, income, and employment (Hilborn et al., 2023). Gear modifications to lessen impacts to the seabed and minimise bycatch of protected species or juveniles can do much to this effect. In addition, management and regulation that reduce the footprint of trawling has shown that this results in higher fish stock yields than if fishing operations are spread over a wider area of seabed (Bloor et al., 2021).

2.5 Marine Protected Areas and Spillover

Hilborn and colleagues (2023) note that sensitive habitats, such as coral reefs or nearshore nurseries, can be protected from fishing activities effectively when locations are known and closed off to vessels, ‘prior to significant disturbance’ (p. 1573). The same is true for non-natural hard substrate, such as shipwrecks and artificial reefs, which provide important habitat for juvenile fish and concentrate populations. For example, vessel-reefs off southeastern Florida were shown to support a higher species richness and abundance than natural reefs and ‘enhanced local fish populations’ (Ross et al., 2016, p. 46). If marine protected areas can be established around shipwreck sites, or areas of numerous wrecks, such as offshore certain historic harbours, they can be protected like other areas of sensitive habitat are. This creates a win-win scenario for both marine environmental protection and cultural heritage protection.

An additional benefit to fisheries management and ecosystem protection comes with the concept of ‘spillover’ where protected areas can allow for populations, especially juveniles, a safe haven to develop, and those populations would then spillover into fishable ground, increasing the fishery. This was put forth for ancient shipwrecks in the Mediterranean area as a management option if marine protected areas were set up around shipwreck sites, juvenile fish populations could thrive and spillover into other areas, thereby protecting the shipwreck sites while helping to increase the fishery (Krumholz & Brennan, 2015). Recent research on seabed recovery from trawl damage has also put forth this argument: ‘The establishment of Marine Protected Areas, such as legally recognized no-take reserves where fishing activity is prohibited, could be a useful management measure… the benefits obtained from MPAs could also be observed in adjacent areas, as a result of the spillover of adults and juveniles from the protected area’ (Vigo et al., 2023, p. 2). Management synergy can be found here between marine environmentalists, fisheries management, and maritime archaeologists. Developing sustainable fishing regulations and promoting those operations, with less destructive gear, for example, can ‘offer de facto protection for UCH’ (Pearson & Thompson, 2023), while establishing protections for UCH can also help sustain and increase fish stocks.

Commercial-scale fisheries exist due to the demand for seafood worldwide. Technological advances in fishing gear and vessels continues to drive the industry to put pressure on marine ecosystems (Clare et al., 2023). Marine protected areas and other no-take type of areas are essential for overfished areas to rebound and enhance fishery yields. Maximising mutual benefits of multi-use areas can help ‘minimize trade-offs between conflicting preferences’ (Clare et al., 2023, p. 1297). Synergy in cultural resources allow shipwrecks to act as artificial reefs and obtain protections themselves within no-fish zones around them. Wrecks have been studied as artificial reefs. The typically vertical structures may not imitate a natural environment but have been shown to ‘establish their own community, which is influenced by the spatial orientation and complexity of the structure’ (Fagundes-Netto et al., 2011, p. 104). Research off Brazil on the metal-hulled wreck of Orion indicate an increase of juvenile fish around the wreck, supporting the spillover concept (Fagundes-Netto et al., 2011). The trouble with establishing marine protected areas around shipwrecks for their protection and for establishment of protected environments is locating shipwrecks, especially those in deep water, which is a main challenge for shipwreck preservation.