|
Novel Species
The main marine finfish species currently farmed in Ireland are
the salmonids, the Atlantic salmon (Salmo salar) and, to
a lesser extent, the rainbow or sea trout (Oncorhynchus mykiss).
Meanwhile, the shellfish farming sector is dominated by extensive
cultivation of native blue mussels (Mytilus edulis), native/flat
oysters (Ostrea edulis), and non-native Pacific oysters
(Crassostrea gigas).
In recent years there has been a growing interest in the culturing
of non-salmonid marine finfish species and alternative shellfish
species (including molluscs, crustaceans and echinoderms), as
well as exotics such as seahorses. Whether native or non-native,
such species are known as novel or new species in marine aquaculture.
Considerable research and development effort
has been expended on extending the range of marine finfish species
that can be farmed commercially. For example, small quantities
of turbot (Scophthalmus maximus) [1] and
halibut (Hippoglossus hippoglossus) have been produced
in land-based facilities on Cape Clear Island, Co Cork.
Trials conducted in Norway, Scotland, Canada and the USA to cultivate
novel temperate water species such as Atlantic cod (Gadus morhua),
haddock (Melanogrammus aeglefinus) and hake (Merluccius
merluccius) are poised to spread to Ireland. The high level
of interest in the commercial production of cod means it is likely
to soon become a reality.
The culture of such species brings with it the
risk of unforeseen problems. Experience from salmon farming shows
how many unexpected impacts, such as diseases and negative interactions
with natural populations, can arise. It is noticeable that in
reviewing the published literature concerning the commercial farming
of these "new" marine fish species, much is known about
the husbandry, economic and marketing aspects of their culture
— but limited consideration seems to have been given to the
relative sustainability and likely environmental footprint of
these developments. Detailed environmental assessments should
be regarded as absolutely vital before commercial production units
are licensed.
Berry and Davison 2001
Some potential novel marine species are non-native. While the
intentional introduction of non-breeding "alien" species
such as the Pacific oyster (Crassostrea gigas) from Japan
has been relatively benign — at least directly — there
is a risk of accidentally introducing and transferring associated
non-target "hitchhiker" species. The cultivation of
the Pacific oyster, for example, has resulted in the introduction
of the invasive Sargassum muticum seaweed into many parts
of Europe and North America. (See Introduced
Species for more details on introductions and transfers of
marine organisms).
Projects aimed promoting species diversification in marine aquaculture
are supported and subsidised at both the EU level, under the umbrella
of the Common Fisheries Policy (see EU
policy on introductions), and the national level by the Irish
Government.
Government support
It is Irish Government policy to support the "diversification
into novel species" by funding marine aquaculture projects
— particularly small-scale projects in a pilot development
phase prior to full-scale commercial development — under
the Aquaculture Development Measure of the National Development
Plan (NDP) 2000-2006. The grant aid is administered through Bord
Iascaigh Mhara/Irish Sea Fisheries Board (BIM), apart from
in Gaeltacht areas where Údarás
na Gaeltachta has funding responsibility, with technical assistance
provided by the Marine
Institute, often via university research institutes.
In 2001, the then Minister for the Marine and Natural Resources,
Frank Fahey TD, made available an extra 5% funding under the Aquaculture
Development Measure as an incentive to projects concerning novel
species developments. The Minister also established the Irish
Aquaculture Working Group on New Species Development (NSD). The
NSD Group was tasked with identifying suitable new species for
fish farming and with drawing-up an integrated plan of action
for the Irish aquaculture industry to facilitate and accelerate
the commercial cultivation of novel species in the short-term,
within the framework of the EU co-funded aquaculture grants scheme.
In May 2002, the NSD Group's report identified turbot (Psetta
maxima), halibut (Hippoglossus hippoglossus) and Atlantic
cod (Gadus morhua) as key species with potential for development
by the industry (IntraFish 2002).
The most recent round of grant aid for aquaculture projects —
including projects concerning development of new species —
under the Aquaculture Development Measure, totalling €13.3 million,
was announced in July 2006. Minister of State at the Department
of Communications, Marine and Natural Resources, John Browne TD,
stressed the importance of diversifying into new species to underpin
future growth in Irish aquaculture (NDP 2006).
Cod farming
In September 2001, BIM held a conference to discuss the potential
for cod farming in Ireland given the gap between demand and supply
created by falling wild catches due to overfishing. The conference
heard from a number of international speakers with a track record
in farming Atlantic cod (Gadus morhua) and other whitefish
species. Delegates heard that in Newfoundland, intensive mass
production of cod fry is now a reality, enabling development of
industrial scale cod farming, and that most of the current salmon
farming technology is directly transferable to cod farming. Dr
Reid Hole, head of the Nutreco Aquaculture Research Centre in
Norway, predicted that the annual production of intensively farmed
cod in Irish waters could be between 5,000 and 10,000 tonnes within
a decade, with haddock and halibut to follow. Dr Hole introduced
the concept of "dedicated industrial marine aquaculture parks",
instead of separate production operations far removed from one
another (IntraFish 2001a).
In Norway, and to a lesser extent Scotland, there has been substantial
investment put in fast-tracking the development of cod farming.
In its 2003 analysis, BIM points to the cost of juveniles and
reliability of stock performance as being major hindrances to
development in Ireland. "Given the head start that our competitors
already have, our studies indicate that production costs will
have to be significantly reduced to make the cod farming sector
commercially viable in the longer term, particularly if there
is any recovery in the volume of the wild catch" (BIM 2003).
Cod farmers may find it more difficult to keep
production costs down initially as juvenile production is still
a technical bottleneck (problems include early survival, physiology,
nutrition and aggression) and is costly. However, one must assume
that these problems will be overcome with increasing knowledge
and economies of scale.
BIM 2003
Ireland's first cod hatchery
Between 2002-2005 a research project entitled "Investigations
into the hatchery rearing of cod (Gadus morhua) in Irish
conditions" was undertaken at the Martin Ryan Institute (National
University of Ireland, Galway) marine research laboratories in
Carna, Connemara. The specific objective was to "identify
and harness potentially exploitable research and technology so
as to enable the establishment of a commercially viable cod hatchery
in Ireland". With €600,000 of State grant aid delivered
through Údarás na Gaeltachta, the project to pilot
the commercial scale production of juvenile cod resulted in the
establishment of Ireland's first custom-built hatchery to rear
juvenile cod and other whitefish species including haddock, hake
and halibut (Galway.Net 2003).
Can cod farming impact wild cod stocks?
In contrast to salmonid farming, with cod farming the whole lifecycle
takes place in seawater. This will in most cases increase the
environmental effects of cod farming compared to that of salmon
and trout farming. Potential environmental impacts arise particularly
from diseases and parasites, with possible transfer to wild fish,
and from genetic and ecological interactions between farmed cod
and wild stocks.
In Norway there has been some conflict between fishermen and fish
farmers concerning whether or not a cod farm can have an impact
on local coastal cod stocks. Theoretically, there are several
ways in which this can happen, including the release of nutrients
and chemicals, and use of artificial light, which could have a
potential impact on local wild cod stocks. Experiments conducted
in 2003 indicate that cod actually avoid seawater that has been
"used" by farmed fish.
Escaped farmed cod
Experience from cod farming in Norway shows that cod exhibit a
different behavior when in the cage, and are much more adaptive
to escaping than are salmon or trout (Fiskeriforskning 2004).
Research reveals that the chances of caged cod escaping are ten
times higher than that of salmon. This is because a cod stays
close to the net where it will quickly see any hole that forms
and then escape. In addition, cod have been shown to chew on the
net, and can actually make holes through which to escape.
WWF-Norway 2005 (edited)
Like farmed salmon, farmed cod are fed with large amounts of
pellets. As with salmon feed, much of this is likely to be made
from fish meal and, to a lesser extent, fish oil sourced from
unsustainable "industrial" fishing on wild stocks.
Turbot farming
From the mid-1990s until 2005, turbot (Scophthalmus maximus)
was farmed commercially at Cape Clear Island, County Cork, in
an onshore tank facility with seawater pumped into it and re-circulated.
The reported 2003 production was 60 tonnes. The Cape Clear farm
is now producing non-native abalone shellfish instead. In 1999,
Heffernan reported that there were three other experimental and
small-scale turbot ongrowing trials: two in Cork and one at Tarbert
in County Kerry.
Abalone farming
Abalone are marine gastropods (sea snails) introduced from abroad.
These molluscan shellfish are a premium-priced luxury product,
and a particularly prized seafood delicacy in Japan. Many wild
populations are subject to overfishing and poaching, and commercial
landings have shown significant reductions worldwide since the
mid-1990s. Hence there is a high level of interest in Ireland
in farming them for export to Asia and ethnic markets in Europe
(BIM 2003).
Abalone are macrophagous, i.e. they are grazers
which feed on seaweed. They occur naturally along exposed coastlines
and show preference for areas with clear oceanic water. Clear
water is essential as their elaborate gills are unsuited to turbid
waters where high silt loads could clog their gills. Abalone in
culture require either a very sheltered environment or cultivation
on sub-surface longlines as they show poor growth rates with excessive
disturbance of their cages. Proper exchange of water is essential
to remove waste products, as build up of waste products can also
lead to reduced growth.
Heffernan 1999
There are two non-native species of interest
to the Irish aquaculture industry; these are the European abalone
(Haliotis tuberculata) and the Japanese or Pacific abalone
(Haliotis discus hannai) [2].
The European abalone (Haliotis tuberculata), commonly
called ormer, was introduced into Ireland in 1976 and 1977 from
Guernsey. After a one-year quarantine period of the imported broodstock
at the NUI Galway Martin Ryan Institute shellfish laboratory at
Carna, the spat was released for ongrowing trials. Due to the
species' preference for red seaweeds, "and the fact that
the species does not particularly like the more common Irish brown
seaweeds or kelps" (BIM 2003), a decision was taken to introduce
the Japanese cold-water abalone Haliotis discus hannai,
also called ezo awabi, to Ireland in 1986.
The Japanese species prefers kelps and can withstand
lower sea temperatures than the European abalone. It has been
found to grow 10% faster than the European abalone in Irish ongrowing
trials. The Japanese abalone is much sought after by Japanese
communities in Europe. This market-led introduction was to offer
a great opportunity to Irish abalone farmers to supply this market.
BIM 2003
About 20kg (wet weight) of seaweed is required to produce 1kg
of abalone (Hensey 1995 cited in Heffernan 1999). Viana et al.
(1996 cited in Heffernan 1999) looked at the possibility of using
silage made from fish and abalone viscera as an ingredient of
abalone feed. "This proved to increase growth rates compared
to a kelp based diet. However, the dangers of feeding animals
their own offal is well documented for example in the transmission
of BSE (Bovine spongiform encephalopathy) in cattle" (Heffernan
1999).
Due to their non-native species status, abalone spat must be
supplied by hatcheries where they are grown in tanks and fed on
algae. In 2003 there were three abalone hatcheries in Ireland,
with more at the planning stage, employing a variety of advanced
techniques to produce abalone (BIM 2003). Once grown to 10-15mm
size, the spat are ready to be transferred into ongrowing units
where the juveniles are grown to market size, which takes about
three years.
In 2003, there were six ongrowing units (i.e. abalone farms)
on the west coast of Ireland, three of which include hatchery
facilities. In 2004-2005, the Cape Clear Island hatchery/land-based
production unit was turned over to abalone farming following the
commercial cessation of turbot farming (RTÉ 2005). BIM
(2003) states:
"The units are land-based, coastal and offer little visual
impact. Due to the high value of the species the volumes cultivated
are small and so facilities in turn can be small. Abalone prefer
warm water in the region of 15-20°C so the ongrowing units are
housed in a specially insulated building with animals growing
optimally at elevated temperatures using recirculation technology…
The discharge or waste from a farm of this nature is also limited
and unlikely to cause any impact on local ecology or habitat.
As both species do not occur here naturally due to temperature
limitations, there is no risk of populations establishing in
the wild." [3]
However, Heffernan (1999) states that the main ecological implications
of growing abalone are likely to be:
- Risk of establishment of a non-native species in Ireland,
thus occupying an ecological niche and competing for already
limited resources.
- Increased pressure on seaweed resources which may not cause
any problems at present, but may do so in the future.
In considering the sustainable development of marine aquaculture,
the Secretariat of the Convention on Biological Diversity (2004)
states that: "In the case of land-based abalone culture,
artificial food is used as supplement to natural feed. This requires
treatment of effluents in order to reduce impacts on the natural
ecosystem."
The importation of abalone for aquaculture in
California in the 1980’s is believed to have resulted in the introduction
of a parasitic worm, posing a significant risk to native abalone
and other mollusks. The worm quickly spread among the state’s
abalone farms and became established in the wild. After several
years the worm was successfully eradicated, and a disease-free
culture environment is currently maintained through a strict program
of hatchery and interfacility transfer regulation, including inspections
and periodic certification of disease free status.
SeaWeb Aquaculture Issues: Diseases
and Parasites
Sea urchin farming
There are two native species of sea urchin (an echinoderm) present
in Ireland, the purple sea urchin (Paracentrotus lividus)
and the green sea urchin (Psammechinus miliaris). Sea urchins
are macrophages, i.e. they graze on algae with a preference for
kelp. To survive, sea urchins require a hard solid surface, usually
a rock crevice or holes, which they bore themselves, especially
in limestone. In the wild they occupy sublittoral habitats from
permanent rock pools at the low-tide level down to boulder strewn
seabed at 30m (Heffernan 1999).
Sea urchin roe has long been considered a delicacy and urchins
have been extensively fished for decades. The world production
of urchins comes essentially from the wild, and Japan consumes
80% of the world's sea urchin roe production.
The sea urchin is considered a delicacy and has
a high commercial value. The edible part of the animal are its
gonads, and urchins are sold either live or the gonads are removed
and sold separately for instance as vacuum packed or canned product.
It is estimated that 80% of the world’s supply of urchins is consumed
in Japan, and Japan imports from at least 13 countries on five
continents. France is the main market for sea urchins in Europe…
In France, urchins are considered a luxury and are not widely
consumed by the public.
BIM 2003
In Ireland, research into the feasibility of culturing purple
sea urchins on a commercial scale has been conducted, with support
from BIM, since the late 1980s at the NUI Galway Martin Ryan Institute
shellfish laboratory at Carna, Connemara.
The first commercial purple sea urchin hatchery
in Ireland was established in Dunmanus, County Cork during the
early 1990s. The hatchery expanded rapidly with its main focus
being on the production of about 1 million juveniles per year
[4]. In tandem with the development of hatchery,
aquaculture licenses were acquired by several individuals for
the purpose of ongrowing these juveniles in intertidal and subtidal
rock pools in the south-west. The urchins grow for four years
before reaching market size. In 2001, some 5 tonnes of urchins
were harvested. In 2003, some 73,000 individual urchin juveniles
were sold by the hatchery. Mature specimens amounting to 320kg
were also sold at €3,850 per tonne. This annual harvest is
expected to rise to between 50 and 80 tonnes by 2006 (BIM 2003).
BIM has stated that this will help to replenish (and otherwise
remove exploitation pressure from) Ireland's wild purple sea urchin
fishery, which has effectively collapsed due to overfishing and
mismanagement. A reported 500 tonnes of urchins were exported
annually in the 1970s, principally to the Paris restaurant market;
in 2001, just five tonnes of urchins were landed. (See Purple
sea urchin fishery).
Heffernan (1999) believes that the main ecological concern with
sea urchin farming would be the harvesting of kelp. "As they
are an overfished native species, ranching could be considered
a form of restocking. This is provided the spat is sourced in
Ireland from native wild stocks."
There are other concerns. BIM (2003) states: "disease identification
and treatment is a particularly difficult area with little work
done to determine prevention methods and possible treatments."
Novel species and disease
transfer
Understanding the mechanism of disease transfer between species
is likely to be one of the main headaches for fish farmers as
diversification into novel species grows, according to a top fisheries
scientist Dr Ron Stagg, deputy director of the Fisheries Research
Service (FRS) Marine Lab in Aberdeen, Scotland.
In August 2001, he told IntraFish news agency: "We have
to be careful how we manage diversification in terms of interactions
between different species. A lot of producers would like to kick-start
the cod industry by growing cod alongside salmon, but we don't
really understand at this point in time what the disease risks
are between these two species, whether there would be the ability
of some pathogens to jump between them, and what the consequences
of that would be. We should be thinking about how we can proceed
safely, and what sort of physical separation we should be looking
for. I believe that if we anticipate problems, we're able to be
strategic in our approach and deal with them sooner and more effectively."
Dr Stagg said that much of the current work in the FRS and other
centres is based on looking at the area of inter-species disease
transfer. "One of the big issues we're dealing with is the
problem of VHS [Viral Haemorrhagic Septicaemia]. There's a very
nasty strain which affects rainbow trout, which we most certainly
want to control, because we have freedom from VHS in our rainbow
trout industry. There are restrictions on trade with some parts
of Europe that have the disease, but of course we've also discovered
in recent years that there's some VHS in the marine environment.
This could possibly result in infections in marine fish farms,
for example in turbot, where we experienced problems in Scotland
and Ireland a few years ago. There have been some recent outbreaks
of VHS in the Baltic, in rainbow trout farms, so the whole question
of how we manage VHS is getting difficult."
"One of the research areas we're looking at is whether there
are different strains that can be distinguished," said Dr
Stagg. "We know that there are pathogenic differences between
strains, and that the turbot type of VHS doesn't really cause
problems in rainbow trout, for example, so there seem to be different
genotypes of VHS and there seem to be different levels of pathogenicity.
It would be very useful to have a tool to distinguish these genotypes
of VHS which cause any problems in rainbow trout but don't cause
any problems in marine species and vice versa, then we may be
able to have separate management regimes for them, that's one
area we're quite active in" (IntraFish 2001b).
|
