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Deep impact: The rising toll of fishing in the deep sea

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The deep ocean is one of the last great wildernesses. Waters deeper than 1000 m cover an estimated 62% of the planet. In spite of more than 150 years of exploration, the ocean depths remain virtually unknown. Biological science has so far touched upon only one millionth of the deep-sea floor, but new technology is revealing unknown and exotic habitats as quickly as we look. Those technologies are also bringing the deep within reach of industry, with devastating consequences.
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Deep impact: the rising toll of fishing in the deep sea
Callum M. Roberts
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The deep ocean is one of the last great
wildernesses. Waters deeper than 1000 m
cover an estimated 62% of the planet. In
spite of more than 150 years of exploration,
the ocean depths remain virtually
unknown. Biological science has so far
touched upon only one millionth of the
deep-sea floor, but new technology is
revealing unknown and exotic habitats as
quickly as we look. Those technologies are
also bringing the deep within reach of
industry,with devastating consequences.
Cast a dredge over the side of a ship far out
to sea and the chances are that you will
raise a bucket full of mud and worms.
Sediment blankets much of the deep-ocean
floor [1] and was a source of endless tedium
for those lowering dredges and raising
mud during the three-year voyage of
HMS Challenger in the 1870s. This voyage
marked the first systematic look at the
biology of the deep sea. Perhaps all that
mud contributed to the suicide, two cases
of insanity and 61 desertions that are
among its lesser known achievements [2].
Dredges are still a mainstay of deep-sea
biology, but today they are supplemented
by a burgeoning array of sophisticated
technology. Remotely operated vehicles,
video, bottom landers, submarines and
sonar now provide windows on the deep
that are forcing us to rethink our notions of
life there. In the past few decades, we have
discovered remarkable new habitats –
spectacular hydrothermal vents, cold
seeps, gas hydrates and cold-water coral
reefs [3]. A closer look at seamounts and
canyons reveals them to be hotspots of
production that harbour diverse faunas
that are rich in unique species.
However, scientists are not the only
ones taking an interest in the deep. These
waters offer the prospect of lavish rewards
to mining, oil and gas exploitation, and
fishing concerns. In a new report prepared
for the World Wide Fund for Nature
(WWF) and World Conservation Union
(IUCN), scientists from the Southampton
Oceanography Centre and an expert on
international law present a primer in
deep-sea biology and explore current
and potential threats to deep water and
high-seas life [3]. Although deep-ocean
mining still lies in the future, fishing is
already causing great concern.
Fishing deeper
Deep-water fisheries began in the 1960s
and 1970s, coinciding with declines in
shallow-water stocks that stimulated the
development of new and more robust
fishing gear [4]. Larger vessels, more
powerful winches, stronger cables and
rockhopper trawls expanded greatly the
reach of fishing. The move to deep water is
being encouraged further by governments
offering grants and subsidies [5] in efforts
to alleviate hardship brought about by
the collapse of shallow-water fish stocks
caused by overfishing. Consequently, there
has been a worldwide scramble to exploit
these resources and 40% of the world’s
trawling grounds are now in waters deeper
than the continental shelves [6].
Early rewards from deep-sea fishing
can be great. For example, the orange
roughy Hoplostethus atlanticus fishery
began in the 1970s. It took off in the 1980s
when spawning aggregations were
discovered around deep seamounts off
New Zealand and southern Australia.
Catches from these aggregations could be
incredible, sometimes 60 t from a 20-min
trawl (J.A. Koslow, pers. commun.).
However, in just over a decade, stocks
collapsed to <20% of their pre-exploitation
abundance, largely through sequential
depletion of aggregations [4,7]. In the
North Atlantic, populations have met with
a similar fate. Here, the mainly French
fishery peaked at 4500 t during its first
two years, then dropped to 1000 t three
years later [5].
Other fisheries have also flourished
briefly then diminished. For example,
pelagic armourhead Pseudopentaceros
wheeleri were fished over seamounts in
international waters northwest of Hawaii
from the late-1960s to mid-1970s. In 1976,
30 000 t were landed but, the year after,
catches collapsed to just 3500 t and have
never recovered [8]. In the North Atlantic,
blue ling Molva dipterygia fisheries also
rely on spawning aggregations. As new
areas are rapidly depleted, the survival of
the fishery depends upon the continuing
discovery of unexploited aggregations [9].
We know from shallow waters that
unregulated or poorly controlled fishing of
aggregations is a quick ticket to fishery
collapse [10]. For example, throughout the
Caribbean, Nassau grouper Epinephelus
striatus spawning aggregations numbering
tens of thousands of fish were eliminated
in just a few years, never to reform [11].
Spawning aggregations concentrate fish
from a very large area into a very small
one. For example, orange roughy travel
hundreds of kilometres to spawn over
seamounts in the Southern Hemisphere
[12]. Aggregations can also form in other
ways. Adult pelagic armourhead, for
example, migrate to seamounts from broad
areas of the northern Pacific, and live out
the rest of their lives there [13]. Where
fishing effort is difficult to control, as it
is on the high seas, exploiting dense
aggregations can be closer to mining than
to fishing, because depletion is rapid and
recovery unlikely [10].
Deep-water fisheries fail the
sustainability test on another ground.
The almost glacial pace of life in the deep
makes it a particularly unsuitable place
to fish. Many species grow slowly and live
to extraordinary ages. For example, new
radiometric aging methods reveal that
rockfish Sebastes spp. longevity increases
exponentially with the deepest occurrence
of a species (Fig. 1), and some species can
reach 200 years old [14]. Cailliet et al. [14]
suggest that great longevity could be
facilitated by slow metabolism. In deep-sea
fish, metabolic rates are typically an order
of magnitude lower than in fish living near
the surface [15]. However, this is not the
only factor – some species dwelling on
seamounts have metabolic rates similar to
those of species living at the surface yet
still live to a great age, perhaps because of
low rates of predation [15].
Long lifespan is usually paired with
late reproduction. Icelandic roundnose
grenadier Coryphaenoides rupestris can
live to their 70s and mature at ~14–16
years old [16]. Orange roughy, which reach
150 years old, do not mature until their
mid-20s to mid-30s [17]. For shallow-water
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Deep impact: the rising toll of fishing in the deep sea
Callum M. Roberts
fish, a large body size and advanced age
at maturity are two of the most reliable
predictors of vulnerability to
overexploitation [18]. Long life, late
maturity and high fecundity are also
indicators of sporadic recruitment success
[18]. The life-history characteristics
of deep-sea species place them at the
extreme end of the vulnerability
spectrum. What these characteristics
point to is that deep-water fisheries are
repeating the process of sequential stock
depletion that has been the hallmark
of shallow-water fisheries [19]. The
difference is that depletion is more rapid,
and recovery will be much slower and even
less certain than in shallow water.
The collateral costs of deep-water
exploitation
Deep-sea fisheries are inflicting terrible
collateral damage. Only a handful of
species is marketable, largely because
most have soft, watery flesh that is
undesirable to consumers and of little use
for fishmeal [5]. Most species are discarded
as bycatch – bykill really, because there is
100% mortality of fish brought up from
great depths [20]. Furthermore, most
deep-sea species are adapted to conditions
of low turbulence. They have large scales,
weak skins and lack the well-developed
mucus coating of shallow water fish [21].
Fish that enter trawls are rapidly stripped
of their scales and skin, so that even small
fish that pass through trawl meshes
probably suffer heavy mortality.
Fisheries are concentrated into areas
with some of the greatest biological
significance in the deep sea. Seamounts,
together with steep slopes, such as those of
canyon walls, are among the few deep-sea
habitats where currents are strong enough
to prevent sediment accumulation. The
same currents also bring food, and a rich
benthic fauna of suspension feeders
develops as a result, including corals,
sponges, seafans and hydroids. This
constant input of food supplies the large
fish aggregations that have attracted
fishers. Koslow et al. [22] found 300 species
of fish and invertebrates inhabiting
Tasmanian seamounts. But many of these
seamounts have literally been stripped
bare by trawling. For example, there was
95% bare rock on fished peaks compared
with just 10% on unfished ones [22], and,
on average, unfished seamounts had
double the benthic biomass and 46% more
species than did fished areas.
The closer we look at the deep sea the
more we challenge our previous ideas.
De Forges et al. [23] reported >850 macro-
and megafaunal species from seamounts
of the southwestern Pacific. This is
striking when you consider that only
597 invertebrate species had been
recorded from seamounts between the
HMS Challenger expedition of the 1870s
and 1987. The new samples reveal
hitherto unsuspected levels of endemism.
Between 29% and 34% of the species
collected were potential seamount
endemics and new to science [23]. Many
species, it seems, have extremely limited
geographical distributions and are
restricted to closely spaced ranges of
underwater peaks. The potential for trawl
damage to cause extinctions is high [24].
Other habitats are being caught in
the fishing crossfire. It is only in the past
five years that the extent of coldwater
coral reefs in the North Sea has been
appreciated, although they were first
described over a century ago [25]. This
habitat occurs at depths of 100–2000 m
and is built largely by a single species of
coral Lophelia pertusa. Growing at rates
of just a few millimetres a year, over
millennia the corals have created reef-like
mounds that can reach up to 200 m high
and 4000 m long [26]. Off the Norwegian
coast, oil companies exploring the seafloor
with remotely operated video cameras
came across a region of reefs that extend
for 13 km [27]. Lophelia beds support a
rich assemblage of species (Fig. 2),
totalling >800 at the last count [28].
Evidence from video suggests that they
also form important nursery grounds for
many fish species.
Video and photographic surveys reveal
troubling evidence of the vulnerability of
this fragile habitat to fishing, including
deep parallel grooves of pulverized coral
ploughed by trawl doors [29]. These doors
keep the net open and the trawl on the
bottom, and deeper trawling and rougher
seabeds require heavier doors, which can
weigh 2–5 t each. Norwegian fishers have
long known of the presence of Lophelia
reefs and developed fishing techniques to
reduce net damage and increase catches
(although only over the short term), such
as dragging chains across the bottom
ahead of trawls to mow down obstructions.
At a recent symposium on deep-water
corals, Norwegian scientists estimated
that up to half of these reefs have already
been damaged or destroyed by fishing
(Fossa et al. 2000; http://home.istar.ca/
~eac_hfx/symposium/).
Across the Atlantic, there are similar
problems. To people fishing off Nova Scotia,
glass sponges are a nuisance. In newly
fished areas, they clog nets with literally
tonnes of material akin to fibreglass. Over
time, the problem diminishes as nets clear
the bottom of its biota. This process of
seabed habitat transformation has been
underway since the early days of trawling.
In the 19th and early 20th centuries,
fishers used to regularly trawl up giant
gorgonians [30]. Radioisotope aging of
smaller colonies put them at hundreds of
years old, suggesting ages of 2000 or more
for the largest specimens [30].
There are fishing methods that are
less destructive to deep-water habitats,
including long-lines, traps and gill nets.
However, the use of gill nets is still
problematic, because lost nets can
continue fishing for very long periods. In
shallow water, the fishing power of lost
nets is rapidly reduced by storms, tidal
currents and fouling algae, but in the calm
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200
150
100
50
01000800600400
Maximum depth of
occurrence (m)
2000
Longevity (y)
Fig. 1. Deep-sea fish generally live longer than do those
in shallow water. The longevity of rockfish species from
the genus
Sebastes
(Pisces: Scorpaenidae) increases
exponentially with their deepest depth of occurrence.
(
r
2=0.51.) Redrawn, with permission, from [14].
Fig. 2.
Lophelia
reef habitat at 273 m on the Sula Ridge,
Norway, showing a cusk fish
Brosme brosme
.
Photograph reproduced, with permission, from Andre
Freiwald, University of Tübingen.
and dark of the deep, nets remain lethal
for much longer. Fishing with long-lines
does less damage to habitats and there is
less wasted bycatch [21], but there is still
no way out of the problem of extremely
low rates of production. For example, the
sustainable annual take of orange roughy
in the southern ocean has been estimated
at only 1.5% of the unfished biomass [31].
Given the high costs of deep-sea fishing
(specialist gear, larger boats and long
voyages) it seems likely that it can be
profitable only if pursued in the present
mode of serial depletion. There is probably
no such thing as an economically viable
deep-water fishery that is also
sustainable. It is clear that the biology
of deep-sea organisms compels us to
rethink attitudes to exploitation that we
have developed from experience with
organisms living in the ‘fast-lane’ of
shallow seas. Merrett and Haedrich [32]
argue that we must consider deep-sea fish
stocks as nonrenewable resources.
Deep-sea ecosystems need urgent protection
The clear cutting of old-growth redwood
forests in the western USA during the
19th century spurred the creation of the
first national parks. The analogy is
obvious. Ancient groves of invertebrates
are being clearcut by trawling just as
quickly and surely as loggers felled groves
of giant redwoods [33]. The unique
megafauna of these hidden aquatic glades
is being hooked and netted faster than
they can possibly be replaced. As with
rainforests, we are probably losing species
far more quickly than we can describe
them. We urgently need to extend
protection to large areas of the deep sea.
Most deep-sea fishing is unregulated
[3], but no licensing, quota scheme or
effort control will save deep-ocean life,
because it can be depleted or destroyed
much too rapidly for these mechanisms
to work. The answer is to create marine
reserves that are entirely off limits to
fishing. Norway moved fast to protect
its coldwater coral reefs from trawling
in 1999, soon after their extent and
vulnerability became known. To date, no
other country has done so. In Australia,
twelve seamounts have been protected
from bottom fishing within the 370 km2
Tasmanian Seamounts Marine Reserve
(Dahl-Tacconi, 2000; http://home.istar.ca/
~eac_hfx/symposium/), New Zealand has
protected 19 seamounts and the USA has
created a small marine-protected area
encompassing two seamounts off Alaska
[34]. However, none is protected from
fishing all the way to the surface. It is still
unclear how closely linked benthic and
pelagic foodwebs are around seamounts.
For example, vertical migrations of
organisms transfer nutrients from shallow
water to bottom habitats. This, together
with the nutrient ‘snowfall’ from animals
aggregated higher in the water column
helps explain why seamount assemblages
are so rich [15]. Consequently, partial
protection measures might not assure
the long-term wellbeing of bottom-living
communities [20,35]. Surface to bottom
protection from fishing offers more security
but could be more difficult to implement due
to greater fishing industry opposition [36].
National initiatives represent a crucial
first step for deep-sea conservation, but
much of the deep lies beyond national
jurisdiction. Fifty percent of the planet
comprises high seas [3], which are outside
the 200-mile national limits. High-seas
regulation poses great challenges [37], but
as the new WWF–IUCN report shows,
present international laws provide a
framework for creating high-seas marine
reserves [3]. Unfortunately, the present
rate of expansion of deep-sea fisheries
gives us little time to act. Unless we
work quickly to establish reserves, we
might realize the Victorian vision of a
deep sea that is devoid of larger life – the
kingdom-of-the-worms once more.
Acknowledgements
This article is dedicated to the memory
of Don McAllister, who saw the need to
protect deep-sea habitats from fishing,
and worked hard to raise awareness
of what we are losing. Julie Hawkins
suggested many improvements to the
article. This work was supported by a Pew
Fellowship in Marine Conservation from
The Pew Charitable Trusts and The Hrdy
Fellowship in Conservation Biology at
Harvard University in the Dept of
Organismic and Evolutionary Biology.
I am very grateful to Sarah and Daniel
Hrdy for endowing the fellowship and to
Steve Palumbi for his hospitality.
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Callum M. Roberts
Environment Dept, University of York, York,
UK YO10 5DD.
e-mail: cr10@york.ac.uk
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... Endangered deepsea species include coral communities, some of which of great environmental importance and that can live for centuries if 30 undisturbed (Bo et al., 2015), and elasmobranch communities that may suffer from by-catch and prey reduction (Barría et al., 2018). In addition to the direct effects of removal and damage of these iconic individuals, deep-sea fishing affects the threedimensional structure of the sea bottom, modifies the turbidity and attracts scavengers, thus resulting in modifications of the overall community composition (Clark et al., 2016;Roberts, 2002). For these reasons, research aimed to protect deep sea areas need detailed estimations of the exploited fishing grounds, and these have become available only in recent years (de Juan and 35 Lleonart, 2010). ...
... In particular, AIS unencrypted radio signals, 45 compulsorily transmitted by European fishing vessels over 15 m to avoid collisions, result in consistent data to observe large trawlers deep-sea targeting shrimps and it has permitted the observation of the supra-national capillary expansion in the eastern regions of the central Mediterranean fleets . Understanding spatio-temporal dynamics of fishing is crucial to prevent stock collapses, especially in deep fishing grounds where several episodes of initial period of high reward followed by phenomenon of local depletion are documented (Roberts, 2002). 50 ...
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Deep-sea fishery in the Mediterranean Sea was historically driven by the commercial profitability of deepwater red shrimps and understanding spatio-temporal dynamics of fishing is key to comprehensively evaluate the status of these profitable resources and prevent stock collapse. A four-year time series of AIS-based observed monthly patterns and related frequency of trawling disturbance are provided with a resolution of 0.01°*0.01°, accounting for the spatial extent and temporal variability in deep water bottom contact fisheries during the period 2015–2018. The dataset was estimated from 370 fishing vessels that were found to perform trawling in deep water (400 m–800 m) during the study period, and they represent a significant part of the real fleet exploiting this fishing grounds in the study area. The reconstructed deep-water trawling effort dataset is available at: https://doi.org/10.17882/89150 (Pulcinella et al., 2022). This large-scale and high-resolution dataset may help researchers of many scientific fields, as well as those involved in fishery management and in the update of existing management plans for deep-water red shrimp fisheries as foreseen in relevant General Fisheries Commission for the Mediterranean (GFCM) recommendations.
... Fishing activity is a serious and worldwide threat to marine ecosystems and their living resources (Roberts, 2002;Morato et al., 2006), severely affecting continental shelves (50-200 m depth) (Halpern et al., 2008). In those environments, under strong currents and food supply, cold-water coral (CWC) species provide reproductive, nursery and feeding grounds for highly diversified associated fauna (Freiwald & Roberts, 2005;Roberts et al., 2009), several of them of commercial interest (Henry & Roberts, 2007). ...
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Cold-water coral (CWC) gardens, mainly composed of gorgonians, soft corals and black corals, support a highly diversified associated mobile fauna, representing a key benthic habitat on the Mediterranean continental shelf. These communities are vulnerable to bottom-contact fishing gears, including trawling and small-scale fishing. In the frame of a collaboration with local fishers, the present study aims to identify the most effective local management measures to significantly reduce impacts while supporting sustainable fishing activity on the continental shelf of Cap de Creus (North-Western Mediterranean Sea). The number and size of gorgonian colonies accidentally captured by trammel nets were quantified, being most of them large colonies. The mean size of bycatch gorgonians was significantly higher. Thus, bycatch effects could lead to changes in population structure and overall ecosystem functioning. However, most bycatch gorgonians came from specific areas, between a specific bathymetric range and were accidentally fished during long soaking time and with high waves conditions. Consequently, avoiding fishing in a restricted selected area when weather conditions are rough may help to significantly reduce the gorgonian bycatch, promoting the conservation of these CWC gardens.
... Fishing activity is a serious and worldwide threat to marine ecosystems and their living resources (Roberts, 2002;Morato et al., 2006), severely affecting continental shelves (50-200 m depth) (Halpern et al., 2008). In those environments, under strong currents and food supply, cold-water coral (CWC) species provide reproductive, nursery and feeding grounds for highly diversified associated fauna (Freiwald & Roberts, 2005 Habitat destruction, mortality and removing of non-target species, and changes in ecosystem structure and functioning are ones of the impacts described, mainly cause by bottom trawling (Hiddink et al., 2006;. ...
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The anemone Amphianthus dohrnii (Koch, 1878) is a small opportunistic epibiont known to colonize a large variety of host species. The species is widely distributed in the eastern Atlantic Ocean and in the Mediterranean Sea, from mesophotic habitats to bathyal depths. Despite being very common, information on its ecology is currently scarce and scattered. The dataset used in this study was obtained during a ROV survey carried out in a wide area of the northern Sicily Channel. In total, 1369 specimens of A. dohrnii were counted. 82.9% of the specimens were observed colonizing dead branches of both living and dead corals, particularly bamboo corals (Isididae), Callogorgia verticillata, Paramuricea hirsuta, Leiopathes glaberrima and Madrepora oculata. Wrecks appear to be also a suitable substrate for A. dohrnii (14.9% of the records). 75.8% of the individuals were observed growing on the dead skeletons of bamboo corals, whose high availability may be related to a poor health status of the population.
... Fishing activity is a serious and worldwide threat to marine ecosystems and their living resources (Roberts, 2002;Morato et al., 2006), severely affecting continental shelves (50-200 m depth) (Halpern et al., 2008). In those environments, under strong currents and food supply, cold-water coral (CWC) species provide reproductive, nursery and feeding grounds for highly diversified associated fauna (Freiwald & Roberts, 2005 Habitat destruction, mortality and removing of non-target species, and changes in ecosystem structure and functioning are ones of the impacts described, mainly cause by bottom trawling (Hiddink et al., 2006;. ...
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Mediterranean echinoderms currently account for 154 species, many of which have been widely studied in coastal ecosystems. Investigations on deep-sea echinoderms, on the contrary, have been challenging in many ways, and very few targeted in situ studies have been carried out so far. Here we took advantage of an extensive ROV survey carried out in the Sicily Channel in 2021 to define the abundance, distribution, ecology and habitat references of two highly abundant yet poorly known deep echinoderms found in the explored area, namely the sea star Hymenodiscus coronata (Sars, 1871) and the holothurian Holothuria (Vaneyothuria) lentiginosa lentiginosa Marenzeller, 1892. About 2400 specimens of the brisingid sea star have been counted during the explorations between 150 and 950 m depth supporting the existence of dense bathyal aggregations on muddy planes. Several specimens of the dotted sea cucumber, an Atlantic species recently reported in the basin, were recorded on different substrates between 140 and 356 m, expanding the knowledge on the ecological preferences and bathymetric distribution of this species.
... Fishing activity is a serious and worldwide threat to marine ecosystems and their living resources (Roberts, 2002;Morato et al., 2006), severely affecting continental shelves (50-200 m depth) (Halpern et al., 2008). In those environments, under strong currents and food supply, cold-water coral (CWC) species provide reproductive, nursery and feeding grounds for highly diversified associated fauna (Freiwald & Roberts, 2005 Habitat destruction, mortality and removing of non-target species, and changes in ecosystem structure and functioning are ones of the impacts described, mainly cause by bottom trawling (Hiddink et al., 2006;. ...
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3rd MEDITERRANEAN SYMPOSIUM ON THE CONSERVATION OF THE DARK HABITATS
... As fish stocks become globally depleted due to improvements in fisheries technology and the gradual deepening of fishing grounds, many deep-sea fisheries have become unsustainable (Roberts, 2002;Morato et al., 2006;Clark et al., 2016). This, along with increasing anthropogenic pollution, makes deep-sea biota at risk and in need of urgent conservation measures (Danovaro et al., 2017). ...
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Although considerable research progress on the effects of anthropogenic disturbance in the deep sea has been made in recent years, our understanding of these impacts at community level remains limited. Here, we studied deep-sea assemblages of Sicily (Mediterranean Sea) subject to different intensities of benthic trawling using environmental DNA (eDNA) metabarcoding and taxonomic identification of meiofauna communities. Firstly, eDNA metabarcoding data did not detect trawling impacts using alpha diversity whereas meiofauna data detected a significant effect of trawling. Secondly, both eDNA and meiofauna data detected significantly different communities across distinct levels of trawling intensity when we examined beta diversity. Taxonomic assignment of the eDNA data revealed that Bryozoa was present only at untrawled sites, highlighting their vulnerability to trawling. Our results provide evidence for community-wide impacts of trawling, with different trawling intensities leading to distinct deep-sea communities. Finally, we highlight the need for further studies to unravel understudied deep-sea biodiversity.
... Van Dover (2011) suggest that having a coherent conservation, management, and mitigation framework for the deep sea is necessary before undergoing deep-sea resources exploitation. We call for further active action and advocacy for working towards science-based management conservation of the deep sea in Costa Rica, following the precautionary principles since the impacts on the deep sea could be irreversible at human timescale (Roberts, 2002;Waller et al., 2007;Hefferman, 2019). ...
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Echinoderms are a highly diverse group and one of the most conspicuous in the deep sea, playing ecological key roles. We present a review about the history of expeditions and studies on deep-sea echinoderms in Costa Rica, including an updated list of species. We used literature and information gathered from the databases of the California Academy of Sciences, the Benthic Invertebrate Collection of the Scripps Institution of Oceanography, the National Museum of Natural History, the Museum of Comparative Zoology and the Museo de Zoología from the Universidad de Costa Rica. A total of 124 taxa (75 confirmed species) have been collected from the Costa Rican deep sea, 112 found in the Pacific Ocean, 13 in the Caribbean Sea, and one species shared between the two basins. We report 22 new records for the Eastern Tropical Pacific, 46 for Central American waters, and 58 for Costa Rica. The most specious group was Ophiuroidea with 37 taxa, followed by Holothuroidea (34 taxa), Asteroidea (23 taxa), Echinoidea (17 taxa), and Crinoidea (11 taxa). The highest number of species (64) was found between 800 m and 1200 m depth. Only two species were found deeper than 3200 m. Further efforts on identification will be required for a better comprehension of the diversity of deep-sea echinoderms. Limited research has been done regarding the biology and ecology of deep-sea echinoderms in Costa Rica, so additional approaches will be necessary to understand their ecological functions.
... Thus, until the end of the 19 th century, it was believed that no life existed in these deep waters and was supported by Forbes' azoic hypothesis based on his observation where he saw a decrease in the number of species with increasing water depth [11]. However, the discovery of living crinoids (sea lilies) from the depths of Norwegian fjords (∼3000 metres) by biologist Michael and Georg Ossian Sars, followed by research expeditions such as the HMS Challenger expedition, shed light on the diverse life forms in the ocean depths [12]. ...
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Deep‐sea fisheries policies promulgated by the Chinese government have contributed to healthy development of deep‐sea fisheries. Using content analysis, we explored the evolution of 159 deep‐sea fisheries policy documents enacted in China since 1979. These policies were divided into three periods: initial start‐up during 1979–2002, optimisation and adjustment during 2003–2016 and rapid development during 2017–2021. During the optimisation and adjustment period, deep‐sea aquaculture policies predominated (more than 80%) and policy focus shifted from deep‐sea fishing to deep‐sea aquaculture. Since then, policy power has intensified, and policy support modes evolved from single to diverse. Future deep‐sea fisheries policies should strengthen scientific and technological innovation support, build stakeholder interest consultation mechanisms, strengthen supervision of ecological impacts on surrounding sea areas and adhere to sustainable development goals.
Chapter
The sustainable exploitation of the marine environment depends upon our capacity to develop systems of management with predictable outcomes. Unfortunately, marine ecosystems are highly dynamic and this property could conflict with the objective of sustainable exploitation. This book investigates the theory that the population and behavioural dynamics of predators at the upper end of marine food chains can be used to assist with management. Since these species integrate the dynamics of marine ecosystems across a wide range of spatial and temporal scales, they offer new sources of information that can be formally used in setting management objectives. This book examines the current advances in the understanding of the ecology of marine predators and will investigate how information from these species could be used in management.
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Over the last twenty years, human exploitation has begun to have an impact in the deep sea, especially in the upper bathyal zone. This has mainly taken the form of deep-sea fishing but more recently oil exploration has extended beyond the continental shelf. Deep-water coral reefs occur in the upper bathyal zone throughout the world. These structures, however, are poorly studied with respect to their occurrence, biology and the diversity of the communities associated with them. In the North-East Atlantic the coral Lophelia pertusa has frequently been recorded. The present review examines the current knowledge on L. pertusa and discusses similarities between its biology and that of other deep-water, reef-forming, corals. It is concluded that L. pertusa is a reef-forming coral that has a highly diverse associated fauna. Associated diversity is compared with that of tropical shallow-water reefs. Such a highly diverse fauna may be shared with other deep-water, reef-forming, corals though as yet many of these are poorly studied. The main potential threats to L. pertusa in the North-East Atlantic are considered to be natural phenomena, such as slope failures and changes in ocean circulation and anthropogenic impacts such as deep-sea fishing and oil exploration. The existing and potential impacts of these activities on L. pertusa are discussed. Deep-sea fishing is also known to have had a significant impact on deep-water reefs in other parts of the world.
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The widespread view that scleractinian corals in cold and deep waters of high latitudes are slow growing organisms that do not form reefs is challenged by the discovery of a huge coral reef over 13 km in length, 10 to 35 m in height and up to 300 m in width formed by the coral Lophelia pertusa in water depths of 270 to 310 m at 64°N on the Sula Ridge, Mid-Norwegian Shelf. Cruises in 1994, 1995 and manned submersible operations in May 1997 provide data and observations from which the structure and development of the Sula Ridge coral reef have been determined. The Fennoscandian icesheet retreated from the Mid-Norwegian shelf prior to 12,000 years before present and modern oceanographic conditions were established at 8000 years before present. Coral growth since that time has resulted in a large deep-water shelf reef for which recent stable isotopic studies have demonstrated high growth rates for these azooxanthellate cold-water corals. Information on the geometry of deep-water coral reefs and their environmental controls is still fragmentary, controversial and raises issues of conservation in this area of active fishing and oil exploration. This paper reports on the discovery of what is probably one of the largest deep-water coral reefs existing in the northeast Atlantic and indicates that its siting is due to post-glacial structures (iceberg plough marks), events (the second Storegga Slide) and local conditions on the seafloor. Surprisingly, reef accumulation rates on the Sula Ridge are comparable with those measured on tropical coral reefs.
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Setting the stage. Diversity and distribution of deep demersal fish. Morphological and life history adaptations. Aspects of fish production: general considerations and feeding. Aspects of fish production: growth and reproduction. Adding a trophic link: exploitation beyond the shelf. The ecology of fisheries. Pandora's box: reflections on the future.
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Major commercial fisheries for orange roughy (Hoplostethus atlanticus) occur on seamount features, which are widely distributed throughout the New Zealand region. When the fishery developed in the late 1970s to early 1980s, it occurred mainly on flat bottom, but over time has become more focused on seamounts. In the 1995–1996 fishing year, it is estimated that about 70 % of the catch of orange roughy within the New Zealand EEZ was taken from seamounts. Seamounts on the Chatham Rise have been fished for over ten years. Examination of commercial catch and effort data show strong declines in catch rates over time, and a pattern of serial depletion of seamount populations, with the fishery moving progressively eastwards to unfished seamounts along the southern margins of the Rise. Catch rates on seamounts in other regions of New Zealand have also generally shown a similar pattern of rapid decline. There is growing concern over the impact of trawling on seamounts, and the effects this can have on the benthic habitat and fauna, and the long-term sustainability of associated commercial fisheries.