wild-caught seafood
TRANSCRIPT
Wild-caught seafood
Swedish fisheries and consumption from a sustainability perspective
Hanna Torén
Örebro University, Academy of Natural Science and Technology
Degree Project, Second Level
Biology, 15 higher education credits
Supervisor: Magnus Engwall
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Contents
Abstract ..................................................................................................................................... 3
Sammanfattning ....................................................................................................................... 3
Introduction .............................................................................................................................. 4
Production capacity .................................................................................................................. 6
Biological impacts ............................................................................................................................... 6
Chemical impacts ................................................................................................................................ 8
Physical impacts .................................................................................................................................. 9
Climate related impacts ....................................................................................................................... 9
Contaminants .......................................................................................................................... 11
Mercury ............................................................................................................................................. 11
Persistent organic pollutants .............................................................................................................. 12
Other contaminants............................................................................................................................ 13
Environmental impact ........................................................................................................... 14
Discussion ................................................................................................................................ 16
Conclusions ............................................................................................................................. 18
Acknowledgement .................................................................................................................. 18
References ............................................................................................................................... 19
Appendix I ............................................................................................................................... 23
Appendix II ............................................................................................................................. 29
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Abstract
Swedish wild-caught seafood is a natural resource that has been utilized for thousands of
years but a variety of anthropogenic impacts affect the aquatic environment in ways that
might impair the opportunity to use the provided ecosystem goods in the future. The objective
of this study is to discuss wild-caught aquatic food resources in Sweden from a sustainability
perspective focusing on long-term production capacity, food safety and environmental impact
of fisheries. Several human impacts (biological, chemical, climatic and physical) is severely
affecting the production capacity and some commercially utilized species face the risk of
extinction. Humans are exposed to methylmercury, persistent organic pollutants and other
contaminants through seafood consumption. Swedish fisheries have severe negative
environmental effects and contribute to global warming, acidification, eutrophication,
spreading of toxins and loss of biodiversity. Lack of knowledge makes it impossible to
completely assess whether Swedish wild-caught seafood is a sustainable food resource but
available information indicate that the current use of and impact on aquatic ecosystem
services are unsustainable and that an increasing part of the Swedish seafood demand will be
met through import.
Sammanfattning
Svensk vildfångad fisk och vildfångade skaldjur är en naturresurs som nyttjats i flera tusen år
men olika typer av mänsklig påverkan på den akvatiska miljön riskerar att försämra
möjligheterna att nyttja dess ekosystemtjänster i framtiden. Syftet med denna studie är att
analysera svensk vildfångad fisk och vildfångade skaldjur ur ett hållbarhetsperspektiv med
fokus på långsiktig produktionsförmåga, livsmedelssäkerhet och fiskets miljöpåverkan.
Mänsklig påverkan (biologisk, kemisk, klimatmässig och fysisk) påverkar
produktionskapaciteten negativt och vissa kommersiellt nyttjade arter är utrotningshotade.
Människor exponeras för metylkvicksilver, organiska miljöföroreningar och andra
föroreningar genom konsumtion av fisk och skaldjur. Svenskt fiske har stor miljöpåverkan
och bidrar till global uppvärmning, försurning, övergödning, spridandet av giftiga ämnen och
förlust av biologisk mångfald. Kunskapsbrist gör det omöjligt att göra en fullständig
bedömning av huruvida svensk vildfångad fisk och vildfångade skaldjur är hållbara
livsmedelsresurser men tillgänglig information indikerar att det nuvarande nyttjandet av och
påverkan på akvatiska ekosystemtjänster är ohållbart och att en ökande andel av den svenska
efterfrågan på fisk och skaldjur kommer att mötas genom import.
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Introduction
Aquatic food is a natural resource that has been utilized by human beings in Sweden since the
colonization during the Mesolithic period (Olson, 2008). The average consumption of
seafood, i.e. fish, crustaceans and molluscs, is approximately 16 kg per capita and year in
Sweden (SBA, 2010). The main species consumed are salmon (Salmo salar), herring (Clupea
harengus), cod (Gadus morhua) and shrimps (Failler et al., 2008). Seafood is a valuable
source of protein, fat (especially polyunsaturated fatty acids), vitamins (especially vitamin D),
minerals and trace elements (Hambreaus, 2009). Consumption of seafood reduces the risk of
cardio-vascular diseases (Becker et al., 2007) and the Swedish National Food Administration
[SNFA] recommends an increased consumption (SNFA, 2010a).
Sweden ranks 48th
in the world on capture production of seafood (Paisley et al., 2010).
Commercial marine fisheries in the North Sea, the Norwegian Sea, Skagerrak, Kattegat and
the Baltic Sea account for the main quantity of seafood landings in Sweden (SBF, 2010a).
Baltic marine fisheries are single species fisheries for cod, sprat (Sprattus sprattus) or herring
while the mixed fisheries of the Swedish west coast fish for a variety of species (Sterner &
Svedäng, 2005). The landings of commercial marine fisheries were 197 000 metric tons in
2009 (SBF, 2010a). 40 % (76 000 metric tons) of the landings consisted of seafood for human
consumption (figure 1). The commercial fishing in Swedish inland waters is mainly located in
the four biggest lakes –Vänern, Vättern, Mälaren and Hjälmaren (SBF, 2010a). The most
important target species are pikeperch (Sander lucioperca), vendace (Coregonus albula),
perch (Perca fluviatilis) and eel (Anguilla anguilla) (Lehtonen et al., 2008). The freshwater
landings by commercial fishermen were 1 600 metric tons in 2009 (SBF, 2010b). The marine
and freshwater catch by leisure fishermen was 13 000 metric tons in 2009 (SBF, 2010c). The
most common species caught by leisure fishermen are perch and pike (Esox lucius).
Figure 1. Seafood landings by Swedish commercial marine fisheries from 1915 to 2009 (SS, 1959;
SBF, 2006; 2010a)
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Seafood is the only major human food source that is primarily harvested from natural
populations – hence capture fisheries solely depend on the production capacity of aquatic
ecosystem services. The supply of ecosystem goods has usually been taken for granted which
has resulted in poor management (Rönnbäck et al., 2007) but environmental protection and
sustainable development are becoming increasingly important issues in fisheries (Roig et al.,
2009). The overall objective of Sweden’s food-related policies is a sustainable production that
ensures food security and protects environmental values (MAS, 2010). This includes a high-
quality and resource efficient food production from the fisheries sector. Sustainability is often
defined as meeting the needs of the present generation without compromising the ability of
future generations to meet their needs (WCED, 1987). Human activities in the past and
present however influence the aquatic environment in ways that might affect the opportunity
to use the provided ecosystem goods and services in the future (Österblom, 2009).
Most environmental toxicants end up in the aquatic ecosystem (Hanson et al., 2009) and some
hazardous substances bioaccumulate in crustaceans and fish which leads to humans being
exposed to them through seafood consumption (Viklund, 2010). One of the goals of the Baltic
Sea Action Plan is a Baltic Sea undisturbed by hazardous substances – a goal that includes an
ecological objective stating that all fish should be safe to eat (HELCOM, 2007). Fisheries are
affecting target-species and non-target species as well as the aquatic and terrestrial ecosystem
(Thrane et al., 2009). The Food and Agriculture Organization of the United Nations [FAO]
have stated that 80 % of the world´s marine fish stocks (groups of fish exploited in a specific
area or by a specific method) are overexploited, depleted or recovering from overexploitation
(FAO, 2009). The objectives of the Swedish fisheries sector are to minimize the direct and
indirect effects of fisheries on biological diversity as well as to attain and maintain a long
term production of Swedish seafood (SBF, 2007a). The outcome of the Swedish National
Environmental Objective “A rich diversity of plant and animal life” should include that
species that are exploited through fishing are managed in such a way that they can be
harvested as a renewable resource in the long term without affecting ecosystem structures or
functions (EOP, 2010).
The objective of this study is to discuss wild-caught aquatic food resources in Sweden from a
sustainability perspective focusing on issues concerning long-term production capacity, food
safety and environmental impact of fisheries.
6
Production capacity
The main limitation for the seafood industry is the availability of raw material (Ziegler &
Hansson, 2003). Table 1 (appendix I) lists the 49 seafood species that are most frequently
caught by Swedish fisheries. The International Council for Exploration of the Sea [ICES] has
made an assessment of the state of 19 fishing stocks among 12 of these species (ICES, 2009).
10 stocks (including 3 stocks of herring) are overexploited and therefore not able to give a
high yield in the future unless fishing pressure is reduced. The population sizes of herring in
the Baltic Sea and Skagerrak have declined by 35–50% during the last three decades (Larsson
et al., 2010). According to Svedäng & Bardon (2003) depletion might be more severe than
concluded by the current stock assessments. 11 of the 49 species listed in table 1 are included
in the Official Swedish Red List (SSIC, 2010). 4 species are categorized as Critically
Endangered (CR) which means that they are considered to be facing an extremely high risk of
extinction in the wild. 5 species (including cod) are listed as Endangered (EN) and are
considered to be facing a very high risk of extinction. The cod biomass in the Baltic Sea is
well below the long term average (MacKenzie et al., 2007) and the adult cod abundance along
the Swedish west coast was reduced by more than 90% between 1982 and 1999 (Svedäng &
Bardon, 2003).
The aquatic ecosystems in Sweden have been submitted to several human impacts (biological,
chemical, climatic and physical) during a long period of time (Degerman et al., 2001;
MacKenzie et al., 2007; Lehtonen et al., 2008). Anthropogenic influence has severely affected
the production capacity of seafood but the relationships between different variables and
responses are difficult to interpret (MacKenzie et al., 2007; Rönnbäck et al., 2007; Lehtonen
et al., 2008; Barange & Perry, 2009).
Biological impacts
The biological impact on aquatic environments has mainly been from fisheries (Degerman et
al., 2001, SBF, 2010c). The worldwide collapse of marine resources is considered to be due to
overexploitation (Sterner & Svedäng, 2005; Leadley et al., 2010) and the decline in adult cod
abundance in Skagerrak and Kattegat are caused by fishing mortality (Cardinale & Svedäng,
2004). Over-exploitation can cause significant extinction risk for marine species and a high
fishing pressure is the most significant threat to 7 of the 11 red-listed species listed in table 1
(SSIC, 2010). 6 out of these are marine species. Fishing mortality is the dominant threat to 11
other marine fish and shark species listed in the Official Swedish Red List including
porbeagle (Lamna nasus) and basking shark (Cetorhinus maximus) (CR), rat fish (Chimaera
monstrosa), thornback ray (Raja clavata) and roundnose grenadier (Coryphaenoides
rupestris) (EN), school shark (Galeorhinus galeus), Greenland shark (Somniosus
microcephalus) and velvet belly lantern shark (Etmopterus spinax) (VU) and Norway redfish
(Sebastes viviparus) (NT). Common skate (Dipturus batis) and Atlantic sturgeon (Acipenser
oxyrinchus) are listed as regionally extinct (RE) since the last individual potentially capable
of reproduction has disappeared from the region. The majority of Swedish lake fisheries are
managed in a biologically sustainable way according to judgments based on current
knowledge (SBF, 2010c). Overfishing is however a threat also to some freshwater fish stocks
and is the major cause of the decline of arctic char in Vättern (Lehtonen et al., 2008).
7
Depleted stocks may not recover even if the fishing intensity is substantially reduced
(Degerman et al., 2001; Sterner & Svedäng, 2005; Cardinale & Svedäng, 2004).
Fishing tends to be selective since gear is designed to remove large (and indirectly older)
individuals (Leadley et al., 2010, Law, 2000). Since fishing mortality often is very high and
the phenotypic variation within species is caused by genetic differences, fishing causes
evolutionary change. Fishery-induced changes in size and age at maturity have been observed
in heavily exploited stocks and might be hard to reverse. In 2000 and 2001 the abundance of
large adult fish of the species cod, haddock (Melanogrammus aeglefinus), whiting
(Merlangius merlangus), plaice (Pleuronectes platessa) and dab (Limanda limanda) in
Skagerrak was very low compared to historical records (Svedäng, 2003). The average
maximum length of the plaice population in Skagerrak and Kattegat has been reduced with 10
cm from 1901 to 2007 and the adult biomass in 2007 was 40 % of the maximum level during
the period (Cardinale et al., 2010). It is however uncertain whether these phenotypic changes
are caused by evolution (Law, 2000) and whether the selection pressure caused by fishing is
compatible with long-term production capacity. Besides changes on the species phenotypic
traits, overfishing might reduce or change the genetic variation within and between
populations (Leadley at al., 2010, Laikre et al., 2005). Different populations should be
harvested separately to avoid overfishing and since a fishery stock may represent only part of
or more than one genetically distinct population the term stock is insufficient when trying to
achieve a biologically sustainable management (Bruckmeier & Neuman, 2005; Laikre et al.,
2005). Genetic information is currently lacking for many of the seafood species exploited in
Swedish waters (Laikre et al., 2005). No changes can however be detected in the amount of
genetic diversity or in the spatial genetic structure of heavily exploited herring in the Baltic
Sea and Skagerrak between 1979/1980 and 2002/2003 (Larsson et al., 2010).
Introductions of new species can be fatal to the original fauna, e.g. through competition and
spreading of diseases, and might be irreversible (Laikre et al., 2005; Lehtonen et al., 2008;
SBF, 2010c). A lot of introductions are performed yearly into Swedish waters – intentionally
through stocking or unintentionally through e.g. shipping – and an increasing amount of
invasive species are occurring on the Swedish coats (Lehtonen et al., 2008; SBF, 2010c).
Illegal introductions of infested non-native signal crayfish (Pacifastacus leniusculus) are
threatening the native noble crayfish (Astacus astacus) by spreading the crayfish plague
(Aphanomyces astaci) (SBF, 2010c). Released or escaped farmed fish may transfer non-
adapted genes to natural populations (Laikre et al., 2005). Salmon that escape from
aquaculture facilities have the capacity for long distance dispersal (Hansen & Youngson,
2010). Rainbow trout (Oncorhynchus mykiss) is a non-native species and the most common
species for stocking and for commercial farming (Lindberg et al., 2009). The dispersal of
released or escaped rainbow trout can be rapid and long-ranged but the inability to find
suitable spawning habitats may be an obstacle to reproduce successfully. Increased shipping
and expansion of aquaculture will increase the risk of invasive species in the future (Leadley
et al., 2010).
8
Chemical impacts
One of the most important factors that contribute to the degradation of aquatic ecosystems is
pollution (Hanson, 2009). Chemical effects include acidification, eutrophication and pollution
from toxic compounds (Degerman et al., 2001). Acidification has deteriorated the ecological
status of several Swedish freshwaters (Lehtonen et al., 2008) and high inorganic Al
concentrations may pose a problem to biota in lakes with low pH values (Wällstedt et al.,
2009). Sulphate deposition has decreased during the last decades leading to the expectations
that fish populations can be reestablished in the formerly acidified lakes (Lehtonen et al.,
2008). Nutrient loads from point sources have decreased during recent decades which can be
seen in the response of freshwater fish but still there are highly eutrophic lakes and rivers that
have high biomasses of less valuable cyprinid fish that are favored by eutrophication – e.g.
roach (Rutilus rutilus), rudd (Rutilus erythrophthalmus) and bream (Abramis brama)
(Degerman et al., 2001; Lehtonen et al., 2008). Eutrophication is a serious problem both on
the west coast (SBF, 2010c) and in the Baltic Sea where it has led to decreased flatfishes and
cod populations (Rönnberg & Bonsdorff, 2004). Decreased transparency caused by
eutrophication has resulted in reduced amount of vegetation used as fish nurseries (Rönnberg
& Bonsdorff, 2004; Rönnbäck et al., 2007). The reduction in Baltic cod recruitment is mainly
caused by lack of available reproduction areas (Rönnberg & Bonsdorff, 2004; Margonski et
al., 2010). Blue mussels (Mytilus edulis) have been favored by increased nutrient loads to the
Baltic Sea because of the increased phytoplankton production (Rönnbäck et al., 2007). Decay
of dead algae leads to depletion of oxygen levels in the water, i.e. hypoxia, and impaired
habitat for multicellular organisms (e.g. flatfishes) in the bottom waters of the Baltic Sea
(Rönnberg & Bonsdorff, 2004; Conley et al., 2009). The reduced oxygen levels leads to
lowered food abundance which indirectly affect higher trophic levels, i.e. fish (Rönnbäck et
al., 2007). Hypoxia supports growth of cyanobacteria which contributes to hypoxia and
sustained eutrophication. The cyanobacteria Nodularia spumigena produces a toxin called
nodularin which may induce liver damage in fish and reduce fish growth and survival
(Persson et al., 2009).
Hazardous substances may damage the ecosystem e.g. through impaired health and harmed
reproduction of animals. Vital physiological functions in fish known to be affected by
pollutants are growth and energy metabolism, liver function and detoxification, immune
defense, ion balance and red blood cell function (Hanson & Larsson, 2009). Even though
pharmaceuticals often are detected at very low concentrations they may pose a risk to biota
due to their biological potency (Roig et al, 2009; Fick et al., 2010). There is little knowledge
about the environmental concentrations and the ecotoxicology of pharmaceutical products –
especially when it comes to their effect on aquatic organisms – but very few cases of serious
adverse effects have been reported. Fish with blood plasma levels of levonorgestrel exceeding
human therapeutic levels have been found in a Swedish study of fish exposed to treated
sewage effluents (Fick et al., 2010). Levonorgestrel is a synthetic steroid that is used in
contraceptives and that has been shown to reduce fish fertility. Health monitoring indicates
that fish are exposed to an increasing amount of environmental pollutants that are unknown or
not subjected to any monitoring (Viklund, 2010). Studies of the gonad size of female perch on
the Swedish Baltic coast have shown a reduced or delayed gonad development due to an
9
increased exposure to environmental pollutants (Hanson et al., 2009). Reduced gonad size and
delayed maturity suggest that reproduction is negatively affected and that the perch
populations are at risk but this has not been shown (Hanson, 2009).
Physical impacts
Habitat loss and fragmentation are among the greatest threats to freshwater fish (Leadley et
al., 2010) and physical impacts like dams and canals have resulted in negative effects
(Degerman et al., 2001). Lake regulation impacts the littoral ecosystems and causes negative
effects on feeding and nursing areas for fish and dams for water-level regulation impede the
access to spawning areas of stream spawners (Lehtonen, et al., 2008). During the two
previous centuries a lot of Swedish streams were channelized to facilitate the transport of
timber on water and riverine fish are still negatively affected by reduced habitat quality
leading to fry displacement and impaired juvenile recruitment (Lehtonen et al., 2008; Palm et
al., 2010). Restoration of channelized streams could therefore benefit fish populations (Palm
et al., 2010). The upstream migration of anadromous salmon and brown trout (Salmo trutta) is
impaired in many Swedish rivers due to hydropower stations (Lundqvist et al., 2008).
Hydroelectric plants and other habitat alterations also increase the loss of downstream-
migrating smolts (Calles & Greenberg, 2009; Serrano et al., 2009). Improved migration
facilities for both upstream spawners and downstream migrants in regulated rivers are
therefore important in order to create self-sustaining populations of threatened salmonids
(Lundqvist et al., 2008; Calles & Greenberg, 2009). Sea lamprey (Petromyzon marinus),
lamprey (Lampetra fluviatilis) and eel are other examples of migratory species that have been
negatively affected by physical barriers constructed by humans (Lehtonen et al., 2008). Today
different activities of fish habitat restoration are directed at rivers and lakes and hydropower
companies perform compensatory stocking of mainly salmon and brown trout.
Coastal habitats – especially vegetated habitats (macroalgae and seagrasses) – support marine
fisheries in Sweden by providing nursery, feeding and breeding areas for the majority of
commercially utilized species (Eriksson et al., 2004; Rönnbäck et al., 2007). Boating
activities in marinas and along ferryboat routes have negative impacts on species richness and
coverage of aquatic vegetation (Eriksson et al., 2004). Habitat destruction is not however the
main threat to cod, haddock, whiting or dab on the west coast (Svedäng, 2003) and does not
represent a limiting factor for recruitment of plaice on the Swedish west coast (Cardinale et
al., 2010). Off-shore energy parks might have positive as well as negative effects on the
species targeted by fisheries (Langhamer et al., 2010). They produce underwater noise,
electric and magnetic fields and hinder commercial fishing but might at the same time benefit
fisheries by providing artificial reefs and no-take areas with the potential to increase fish
abundance, species richness and fish size.
Climate related impacts
Fish stocks are susceptible to a variety of climate change impacts and the vulnerability of
fisheries is likely to be higher where they already suffer from overexploitation (Daw et al.,
2009). High latitude aquatic ecosystems will face a reduced ice cover, warmer water
temperatures and a longer growing season resulting in increased primary production (Barange
& Perry, 2009). Ocean acidification is predicted to increase due to the increased uptake of
10
carbon dioxide – a process that will harm shell-borne organisms and corals (Leadley et al.,
2010). Climate change will lead to spreading of pathogens to higher altitudes (Barange &
Perry, 2009) and to increased rainfall that might affect the distribution and bioavailability of
chemicals in coastal areas (Hanson et al., 2009). Climate change and warmer winters
increases the variability in nitrate concentrations which may pose a major challenge to biota
in Swedish lakes (Weyhenmeyer, 2009).
The ability of fish to adapt to changing environments is species-specific and all fish
populations will not be able to adapt to the predicted climate change (Lehtonen et al., 2008).
The range of warmer-water species will expand while the range of cold-water species will
contract (Barange & Perry, 2009). The ranges of Swedish freshwater species are determined
primarily by climate, especially temperature, and climate change will probably lead to the
decrease or collapse of cold water fish populations (Lehtonen et al., 2008). The catch of cold-
water species like burbot (Lota lota), maraene (Coregonus maraena), vendace and char
(Salvelinus umbla) in Swedish commercial freshwater fisheries have declined from 1994-
2009 while the catch of warmer-water species like perch, asp (Aspius aspius), pike, pikeperch,
bream, roach and tench (Tinca tinca) have increased during the same period (SBF, 2010c).
Climate, i.e. magnitude and frequency of inflow into the Baltic as well as water temperature,
is affecting cod, herring and sprat recruitment in the Baltic Sea through different opportunities
for egg and larval viability (Nissling, 2004; Margonski et al., 2010). Decreasing frequency of
inflows of salty and oxygenated North Sea water have had a negative effect on Baltic Sea
ecosystem (Jansson & Stålvant, 2001). The knowledge about effects of temperature on cod
reproduction is inconclusive (MacKenzie et al., 2007). According to Margonski et al. (2010)
mild winters are related to low cod recruitment while herring and sprat recruitment are
positively related to temperature. Nissling (2004) states that temperature has no significant
effect on cod reproduction but that sprat egg and larvae show a higher survival in higher
temperatures. Climate changes have contributed to the increasing sprat population in the
Baltic Sea (Casini et al., 2008).
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Contaminants
Environmental pollutants are characterized by often being environmental persistent and
bioaccumulating as well as produced in large amounts and used in ways that enable them to
spread to the environment (Viklund, 2010). The intake of hazardous substances from fish
varies considerably depending both on amount of fish consumed and catchment area of the
consumed fish (Berger et al., 2009). The balance between health benefits and risks due to
dietary fish intake is not very well understood (Mikoczy & Rylander, 2009). A Swedish study
of consumers with high dietary intake of marine fish showed that west coast fishermen and
their wives had a decreased overall mortality and significantly fewer deaths from respiratory
and cardiovascular diseases as well as a lower than expected cancer incidence – findings that
could indicate a positive impact of high fish consumption (Berger et al., 2009). These effects
were not shown for east coast fishermen and their wives who had higher concentrations of
persistent organic pollutants [POPs] in blood as well as a higher consumption of fatty fish.
Mercury
Human activities are responsible for a significant part of the dispersion of heavy metals
(Mukherjee et al., 2004) and long-range transport by air pollution is the origin of most of the
Hg in freshwater fish in Sweden (Bishop et al., 2009). There is a clear indication that forest
harvesting leads to increases in mercury bioaccumulation in downstream aquatic biota. Half
of the Swedish lakes contain high concentrations of Hg (Mukherjee et al., 2004).
Methylmercury (MeHg) is the form of mercury that is most susceptible to biomagnification in
the aquatic food chain and is therefore the dominant form of Hg in fish (Bishop et al., 2009).
Ingestion through food is generally the most important pathway for mercury exposure
(Mukherjee et al., 2004). MeHg in food is almost completely absorbed in the human
gastrointestinal tract and is spread to all body tissues (Becker et al., 2007). Methylmercury
can damage both the peripheral and the central nervous system (CNS) and the most
significant risk occurs during prenatal CNS development.
Samples taken from 2001 to 2009 of pike (several lakes), perch (Baltic Sea and several lakes),
burbot (Vättern & Vänern), salmon (Vättern) and brown trout (Vättern & Vänern) have
exceeded the maximum level of mercury in muscle meat of fish stated in the regulations on
maximum levels for certain contaminants in food (EC No 1881/2006) established by the
Commission of the European Communities (Petersson- Grawè et al., 2007; IVL, 2010;
Sundström & Jorhem, 2010). The development of mercury concentrations in marine biota is
not consistent and significant increasing as well as decreasing trends are observed for herring
(Bignert et al., 2010). Increasing trends are observed for cod, burbot and blue mussels while a
decreasing trend is observed for perch. The Hg concentrations in char from Vättern have
increased during the last period of years (SBF, 2010c). The precipitation of mercury
compounds has decreased during the last decades but increased leakage from forest areas after
windfalls caused by winter storms may increase Hg levels in fish in the future (Lehtonen et
al., 2008).
SNFA recommends limited intake of perch, pike, pikeperch, burbot, halibut (Hippoglossus
hippoglossus), shark, ray and eel due to high levels of mercury (Becker et al., 2007). Pregnant
and breastfeeding women and women of child-bearing age who anticipate becoming pregnant
12
are recommended to refrain from eating these kinds of fish. The MeHg exposure of the
majority of Swedish population is at a safe level compared to tolerable daily intake (TDI)
recommendations. A few percent of Swedish children and pregnant women have higher than
recommended intake of mercury. There are big differences in the consumption pattern and a
small minority of the population who consume large amounts of fish with elevated MeHg
levels might have an intake so high that it increases the risk of cardiovascular diseases.
Persistent organic pollutants
Dioxins (polychlorinated dibenzo-para-dioxins [PCDDs] and polychlorinated dibenzofurans
[PCDFs]) and PCBs (polychlorinated biphenyls) are examples of persistent organic pollutants
[POPs]. Dioxins are unintentionally created during combustion of organic materials and PCBs
have been used in a wide variety of manufacturing processes (Bignert et al., 2010).
Sediments, atmospheric deposition and freshwater inputs are sources of POPs in aquatic
systems (Sundqvist et al., 2009). POPs are important environmental pollutants because of
their lipophilic properties, their ability to bioaccumulate, their ability to long-distance
transport and their long half-life times (Rignell-Hydbom et al., 2009; Hardell et al., 2010).
Dairy products and fatty food are the main sources of human exposure to PCB (Hardell et al.,
2010). Dioxins and PCBs are well absorbed in the human gastrointestinal tract and are spread
in the adipose tissue (Becker et al., 2007). Dioxins and PCBs can have negative effects on the
CNS, the immune system and the development of organs and some are classified as
carcinogenic substances.
Samples of salmon (Baltic Sea and several rivers), trout (several rivers), herring (Baltic Sea),
char (Vättern) and vendace (Vänern) have exceeded the maximum levels of dioxins stated in
EC No 1881/2006 (Ankarberg et al., 2007; SNFA, 2010b). Samples of salmon (Baltic Sea and
one river), trout (several rivers) and herring (Baltic Sea) have exceeded the maximum levels
of dioxins and dioxin-like PCBs. There is no significant change in the concentrations of
dioxins in herring from the Baltic Sea and Kattegat (Bignert et al., 2010). The concentrations
of PCBs in herring and cod from the Baltic Sea and Kattegat, perch from the Baltic Sea, blue
mussels from Kattegat and char from Vättern show a significant decreasing trend as a result
of restrictions (Bignert et al., 2010; SBF, 2010c).
SNFA recommends limited intake of herring from the Baltic Sea, salmon and trout from the
Baltic Sea, Vänern and Vättern as well as char from Vättern due to high levels of dioxins and
PCBs (Becker et al., 2007). Fish account for about half of the food intake of dioxins in
Sweden. The median intake of dioxins and dioxin-like PCBs in Swedish adults is
approximately half of the TDI but 14 % of the population has an intake that exceeds TDI. 5 %
of the women of reproductive age have an intake that exceeds TDI – mainly because of a high
consumption of fatty fish from the Baltic Sea. 65 % of four year old, 41 % of eight year old
and 14 % of eleven year old Swedish children have an intake of dioxins and dioxin-like PCBs
that exceeds the recommended TDI. There was a decreasing trend for the sum of PCBs in
samples of Swedish men and women during 1993–2007 (Hardell et al., 2010).
13
Other contaminants
The nuclear power plant accident in Chernobyl 1986 caused significant radioactive fallout in
Sweden and constant monitoring of radiation will be required for several generations to come
(Nesterenko et al., 2009). The radioactivity has dropped but quite high levels can still be
measured in some lakes (Lehtonen et al., 2008; Nesterenko et al., 2009). The maximum level
of 1500 Becquerel/kg wet weight set by SNFA was exceeded in Swedish samples of perch,
pike, trout and char during 2000-2002 (LIVSFS 1993:36; SRSA, 2010). SNFA recommends
limited intake of fish with more than 300 Bq/kg wet weight and zero intake of fish with more
than 10 000 Bq/kg wet weight (Becker et al., 2007). Levels exceeding 10 000 Bq/kg wet
weight have been measured in samples of perch in 2000 and 2001 and in pike in 2001 (SRSA,
2010).
The use of chemicals has increased steadily and several substances with potential negative
effects are released into the environment (Hanson & Larsson, 2009). Only a small fraction of
the substances in use are subjected to environmental monitoring (Viklund, 2010). Fish is one
of the media that is included in the Swedish Screening Programme for certain hazardous
substances (SEPA, 2009). The following substances have been detected in fish muscle:
organophosphates, octadecyl-3-(3,5-di-tert-butyl-4-hydroxiphenyl)-propionate, silver, mysk
substances, hexavalent chromium, palladium and bisphenol A. These findings indicate that
fish consumed by humans are a source of human exposure to various potential problematic
substances. Fish caught in polluted freshwater systems can be a significant source of dietary
human exposure to perfluorinated alkyl substances [PFAS] and may continue to be for many
years or decades to come (Berger et al., 2009). The current knowledge about perflourinated
substances is not sufficient to make a risk assessment of PFAS in food (Ankarberg et el.,
2007).
14
Environmental impact
Fishery activities and the exploitation of target species have direct and indirect effects on non-
target species, the aquatic ecosystem and the entire environment – resulting in feedback
effects on target species (Thrane et al., 2009). Environmental impacts of fisheries vary
considerably depending on e. g. target species and fishing method (table 2, appendix II).
Swedish fisheries have a negative impact on 8 out of 16 Swedish Environmental Objectives;
“A balanced marine environment”, “Flourishing coastal areas and archipelagos”, “Flourishing
lakes and streams”, “A rich diversity of plant and animal life”, “A magnificent mountain
landscape”, “Reduced climate impact”, “Natural acidification only”, “Zero eutrophication”
and “A non-toxic environment” (SBF, 2007b).
Environmental impacts of fisheries occur in the fishing stage and in the post-landing phases of
the products life cycle, i.e. in the processing industry, sale and transport processes, during
shopping, cooling and food preparation as well as during disposal of packaging and leftovers
(Thrane et al, 2009). Life Cycle Analysis [LCA] of cod from the Baltic Sea and Norway
lobster from Kattegat reveal that fishery is the phase that contributes the most to global
warming potential, acidification, eutrophication, aquatic ecotoxicology and photochemical
ozone creation (Ziegler et al., 2003; Ziegler & Valentinsson, 2008). This is mainly due to
diesel production and combustion which are the processes that account for the majority of the
energy consumption. The amounts of greenhouse gas emissions produced by marine diesel
engines are considerable and contribute to climate change as well as to acidification and
eutrophication (Ziegler & Hansson, 2003; Daw et al., 2009). Beam and bottom trawls are
generally the most fuel consuming fishing methods (Thrane et al., 2009, table 2).
Overexploitation of seafood resources is increasing the environmental impact of seafood
production by reducing the catch per unit effort (Ziegler & Hansson, 2003; Ziegler et al.,
2003; Daw et al., 2009; Thrane et al., 2009).
The discards in Swedish fisheries are significant (Ziegler et al., 2003; Ziegler & Valentinsson,
2008) and correspond to 5-20 % of the total catch of cod, more than 50 % of the total catch of
plaice, haddock and witch (Glyptocephalus cynoglossus) and 85 % of the total catch of
whiting (SBF, 2010c). The discards include several additional species e.g. flounder
(Platichthys flesus), Nephrops, dab, turbot (Psetta maxima), long rough dab (Hippoglossoides
platessoides), brown crab (Cancer pagurus), gurnard (Eutriglia gurnardus) and hake
(Merlucchius merlucchius) (Ziegler et al., 2003; Ziegler & Valentinsson, 2008). Almost all
the discarded individuals die. Discard in fisheries contributes to eutrophication (Ziegler &
Valentinsson, 2008). An improved selectivity has the potential to reduce the discard rates by
reducing the catch of fish below the minimum landing size (Madsen et al., 2010).
The goal of Swedish fisheries management is to choose the fishing methods that cause the
least possible environmental damage (SBF, 2007a) but a significant proportion of the seafloor
is currently affected by fishing gear targeting demersal seafood species (Nilsson & Ziegler,
2007; Ziegler & Valentinsson, 2008). 44 % of the total Kattegat area was affected by trawling
by Swedish fishermen during 2001-2003 (Nilsson & Ziegler, 2007). Corals, sponges,
polychaetes and bivalves are very sensitive to fishing disturbance and are damaged both by
direct physical impact of the fishing gear and by sediment material clogging the filtering
15
organs. Species with long life-cycles, slow recruitment and low fecundity are more sensitive
than species with other life history strategies. Muddy seafloor areas are considered to have a
high recoverability but approximately 40 % of the muddy seafloors in the Kattegat remain in
a continuously disturbed condition due to trawling (Nilsson & Ziegler, 2007; Ziegler &
Valentinsson, 2008). Even very low levels of fishing intensity will have a high impact on
habitats with fragile components (e.g. coral reefs) (Nilsson & Ziegler, 2007). Abandoned, lost
or otherwise discarded fishing gear has a number of environmental impacts including
continued catch of and interactions with target and non-target species (Ziegler et al., 2003;
Ziegler & Valentinsson, 2008; Macfadyen et al., 2009).
The disappearance of top marine predators can cause major ecosystem changes due to top-
down processes (Casini et al., 2008). Intermediate predators may increase and reduce the
abundance of mesograzers like small crustaceans and gastropods, causing an increase of
nuisance algae (Baden et al., 2010). The interaction between bottom-up and top-down
processes can be complex but overfishing may play an important role in the decline of
eelgrass (Zostera sp.) in Skagerrak. The sharp decline in cod biomass has resulted in a trophic
cascade effect in the Baltic Sea during the past three decades (Casini et al., 2008). The decline
of the top predator fish has been followed by an increase in its main prey, the
zooplanktivorous sprat, a decrease in zooplankton and an increase of phytoplankton. The
observed cascade effects have caused a reorganization of the Baltic Sea ecosystem (Casini et
al., 2009). Two alternative ecosystem structures (one cod-dominated and one sprat-
dominated) that are separated by an ecological threshold (a certain level of sprat abundance)
have been identified. These alternatives are characterized by different functioning and
stability. Current conditions of high sprat abundance may impair cod recruitment by top-down
regulation of sprat on the food resources for cod larvae and ultimately undermine both cod
and ecosystem recovery (Casini et al, 2008; 2009). The ecosystem change in the Baltic Sea
may therefore be hard to reverse.
16
Discussion
The knowledge of the aquatic ecosystems is relatively poor and the natural state is often
unknown which makes it very difficult to detect and value changes (Rönnbäck et al., 2007;
Leadley et al., 2010; Cardinale et al., 2010). Uncertainties regarding future impact on
ecosystem services, organism’s ability to adapt as well as complex interactions between
ecological, social and economic systems make long term predictions extremely uncertain
(Barange & Perry, 2009; Daw et al., 2009; Leadley et al., 2010). Hence the current
information and knowledge is insufficient when attempting to completely assess whether
Swedish wild-caught seafood is a sustainable food resource.
When it comes to long-term production capacity, the status has only been assessed for a
minority of the utilized stocks and the feedback systems that prevent recovery of fish
populations are far from fully understood (Nilsson & Ziegler, 2007; Leadley et al., 2010).
There is however available data that clearly shows that the current use of wild populations of
fish, crustaceans and molluscs is threatening the long-term production capacity and that some
of the damages may be impossible or hard to reverse. The environmental impacts of fisheries
are only beginning to be understood (Leadley et al., 2010) and current LCA methods are not
adapted to assess environmental impacts of fisheries (Thrane et al., 2009) but the available
information reveals that Swedish fisheries have severe negative environmental impacts.
Nature may not be very fragile due to its ability to shift into new states but the maintenance of
ecosystem services on which human societies depend (e.g. production capacity of wild
populations of fish, crustacenas and molluscs) may be (Rönnbäck et al., 2007). Lack of
information is a problem also when trying to assess the food safety of wild-caught seafood.
Knowledge regarding the occurrence in seafood and risks associated with consumption are
lacking for a huge amount of substances. The environmental persistence and increasing trends
of some contaminants are however concerning.
The previous sections reveal several future challenges associated with wild-caught aquatic
food resources in Sweden. A variety of human impacts – including fisheries – are threatening
the future production capacity and food safety of Swedish seafood. The total demand of
seafood is however expected to increase in Sweden during the following two decades and
imports of seafood are expected to increase as a consequence (Failler et al., 2008). Import is
already today an important and growing source of seafood. Sweden imported more than
500 000 metric tons of seafood in 2009 and the amount have increased with approximately 60
% since 2004 (SS, SBA, 2010). The maximum production potential of the world’s capture
fisheries have been met but the demand for seafood will increase in the future leading to
increased fishing pressure and decreased future global landings of seafood (Leadley et al.,
2010). One way to increase the production of capture fisheries could be to fish for species that
are not utilized at all or under-utilized today. Aquaculture is another way to increase world
supply of seafood. Aquaculture accounts for about 45% of the fish consumed by humans
worldwide and aquaculture production is expected to increase in many parts of the world
(Paisley et al., 2010). However aquaculture relies on wild populations since captured seafood
is used as feed for some cultured species and since wild populations are used by aquacultures
to obtain broodstock or juveniles (FAO, 2009). The global aquaculture will continue to grow
17
but the growth rate will decrease and it could not be taken for granted that the growth in
production will match the growing demand.
Domestic aquaculture is another alternative source of supply. Sweden has good conditions for
aquaculture but a limited production – mainly of rainbow trout, blue mussels and char
(Paisley et al., 2010). There are several environmental impacts connected to aquaculture
including eutrophication, the use of feed and the risk of spreading genetic material, diseases
and parasites (Ziegler, 2008). The aquaculture production in Sweden is expected to remain
constant or decline until 2030 because of environmental concerns and regulations (Failler et
al., 2008; Paisley et al., 2010). Farming of blue mussels that feed on phytoplankton may be a
sustainable method for producing seafood while simultaneously decreasing marine
eutrophication (Lindahl et al., 2005). Blue mussel farming for consumption and for absorption
of pollutants and prevention of eutrophication will probably increase as will oyster farming
but the quantities produced will remain limited (Failler et al., 2008; Paisley et al., 2010).
Farming of Arctic char in hydroelectric water reservoirs may improve the local environment
by increasing the nutrient levels (Paisley et al., 2010). One idea is to move nutrients from the
Baltic Sea to oligotrophic rivers by catching fish in the Baltic Sea and use it to feed farmed
Arctic char (Eriksson et al., 2010). Aquaculture might also be a way to produce safe seafood
since farmed fish generally contain significantly lower levels of contaminants compared to
wild-caught fish (Becker et al., 2007).
A considerable amount of Swedish wild-caught seafood is in fact reared and released.
Stocking is a widely used method to compensate for the damages to fishing and to prevent
wild populations from becoming extinct (Laikre et al., 2005; Rönnbäck et al., 2007; Lehtonen,
et al., 2008). Except for direct human consumption Swedish seafood farms produce fish for
the national conservation of species program, for restocking and for put-and-take fisheries
(Paisley et al., 2010). The farmed species include rainbow trout, brown trout, salmon, Arctic
char, eel, pike-perch and crayfish. There is criticism about the practice of releasing reared fish
and according to Laikre et al. (2005) it is often carried out to be able to maintain a high
fishing pressure that may result in overharvest of the wild populations.
To change the diet is one approach to reduce the environmental impact of human activities in
order to reach sustainability. The amount of energy used to produce seafood might be very
high or fairly low compared to other sources of protein (Carlsson-Kanyama & González,
2009; Ziegler, 2008) since there are considerable differences in the environmental impact of
different seafood production systems. People might choose seafood that is produced in a more
sustainable way if they are given the choice and sustainable production is becoming
increasingly important for marketing reasons (Ziegler & Hansson, 2003). Increased seafood
consumption does not have to result in an increased environmental impact if consumers
choose seafood with relative low impact (Ziegler, 2008).
This study is far from conclusive regarding factors affecting the sustainability of wild-caught
aquatic seafood in Sweden. Focus has been on anthropogenic influences on production
capacity and the impacts of predators like seals and cormorants are for example not taken into
consideration. Only contaminants originated from human-induced pollution are included in
18
the assessment of food safety while seafood as source of infection is not. The study have been
focusing on ecological factors of sustainability but when dealing with issues of sustainability,
social as well as economic considerations have to be taken into account. It is also important to
bear in mind that there are other values, except from production, connected to aquatic
ecosystems, e.g. stabilizing and regulating biological functions, cultural values (i.e.
recreational and educational functions) and existence values (Rönnbäck et al., 2007; SBF,
2007a).
Conclusions
- Lack of knowledge makes it impossible to completely assess whether Swedish wild-
caught seafood is a sustainable food resource.
- Available information indicate that the current use of and impact on Swedish aquatic
eco-system services are unsustainable and threatening the long-term production
capacity and food safety of wild-caught seafood.
- The future increasing demand of seafood in Sweden will probably be met by import of
wild-caught and cultured fish and shellfish.
Acknowledgement
Thanks to Magnus Engwall for valuable support.
19
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för miljömålsfrågor
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2010
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386-394
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23
Appendix I
Table 1. The 49 seafood species most frequently caught in Swedish fisheries, catch for human consumption by marine and freshwater commercial fishermen in 2009
and leisure fishermen in 2006, stock assessments according to ICES Advice 2009 and assessments of extinction risk and most significant threat according to the 2010
Red List of Swedish Species (SBF, 2009, 2010a,b; ICES, 2009; SSIC, 2010).
Species Catch
(million kg)
ICES Advice Red List
Spawning biomass in
relation to
precautionary limitsi
Fishing mortality in
relation to
precautionary limitsii
Fishing mortality in
relation to highest
yieldiii
Categoryiv Most
significant
threat
Herring (Clupea harengus)
Eastern Baltic Sea
Bothnian Sea
Western Baltic Sea, Kattegat and
Skagerrak (spring spawners)
North Sea, Kattegat and Skagerrak
(autumn spawners)
39
-
-
-
Increased risk
Increased risk
Harvested sustainably
-
Harvested sustainably
Overexploited
Appropriate
Overexploited
Overexploited
- -
European sprat (Sprattus sprattus)
Baltic Sea
16
-
Increased risk
Overexploited
- -
Cod (Gadus morhua)
Western Baltic Sea
Eastern Baltic Sea
14
Increased risk
-
-
Harvested sustainably
Overexploited
Appropriate
EN High fishing
pressure
24
Species Catch
(million kg)
ICES Advice Red List
Spawning biomass in
relation to
precautionary limitsi
Fishing mortality in
relation to
precautionary limitsii
Fishing mortality in
relation to highest
yieldiii
Categoryiv Most
significant
threat
Kattegat
North Sea and Skagerrak
Reduced reproductive
capacity
Reduced reproductive
capacity
-
Increased risk
-
Overexploited
Mackerel (Scomber scombrus)
Northeast Atlantic
8
Full reproductive
capacity
Increased risk
Overexploited
- -
Pike (Esox lucius)
3 - - - - -
Perch (Perca fluviatilis)
3 - - - - -
Northern shrimp (Pandalus borealis)
2 - - - - -
Saithe (Pollachius virens)
Skagerrak, Kattegat and the North Sea
1
Full reproductive
capacity
Harvested sustainably
Appropriate
- -
Norway lobster (Nephrops norvegicus)
1 - - - - -
Vendace (Coregonus albula)
1 - - - - -
Trout (Salmo trutta)
Baltic Sea
1
Populations are on
average much below
potential
-
-
- -
Maraene (Coregonus maraena)
1 - - - - -
Greater weever (Trachinus draco)
1 - - - - -
Pikeperch (Sander lucioperca) 0,1-1 - - - - -
25
Species Catch
(million kg)
ICES Advice Red List
Spawning biomass in
relation to
precautionary limitsi
Fishing mortality in
relation to
precautionary limitsii
Fishing mortality in
relation to highest
yieldiii
Categoryiv Most
significant
threat
Salmon (Salmo salar)
Baltic Sea
0,1-1
Low at-sea
(post-smolt)
survival in recent
years threatens
stock recoveries
-
-
- -
Rainbow trout (Oncorhynchus mykiss)
0,1-1 - - - - -
European eel (Anguilla anguilla)
0,1-1 - - - CR Not known
Small sand eel (Ammodytes marinus)
& Lesser sand eel (Ammodytes
tobianus)
North Sea
0,1-1
Increased risk
-
-
- -
European plaice (Pleuronectes
platessa)
North Sea
0,1-1
Full reproductive
capacity
Harvested sustainably
Overexploited
- -
Char (Salvelinus umbla) & Arctic char
(Salvelinus alpinus)
0,1-1 - - - - -
Grayling (Thymallus thymallus)
0,1-1 - - - - -
Haddock (Melanogrammus aeglefinus)
North Sea and Skagerrak
0,1-1
Full reproductive
capacity
Harvested sustainably
Appropriate
EN High fishing
pressure
European flounder (Platichthys flesus)
0,1-1 - - - - -
26
Species Catch
(million kg)
ICES Advice Red List
Spawning biomass in
relation to
precautionary limitsi
Fishing mortality in
relation to
precautionary limitsii
Fishing mortality in
relation to highest
yieldiii
Categoryiv Most
significant
threat
Brown crab (Cancer pagurus)
0,1-1 - - - - -
Crayfish
Signal crayfish (Pacifastacus
leniusculus)
European crayfish (Astacus astacus)
0,1-1
-
-
-
-
-
-
-
CR
-
Crayfish
plague
Witch (Glyptocephalus cynoglossus)
0,1-1 - - - - -
Angler (Lophius piscatorius)
< 0,1 - - - - -
Spiny Dogfish (Squalus acanthias) < 0,1 - - - CR High fishing
pressure
Lumpsucker (Cyclopterus lumpus)
< 0,1 - - - NT Not known
Whiting (Merlangius merlangus)
North Sea
< 0,1
-
-
Overexploited
VU High fishing
pressure
European hake (Merlucchius
merlucchius)
Skagerrak, Kattegat and the North Sea
< 0,1
Full reproductive
capacity
Harvested sustainably
Overexploited
- -
Atlantic pollock (Pollachius
pollachius)
< 0,1 - - - CR High fishing
pressure
Turbot (Psetta maxima)
< 0,1 - - - - -
Common ling (Molva molva) < 0,1 - - - EN High fishing
pressure
27
Species Catch
(million kg)
ICES Advice Red List
Spawning biomass in
relation to
precautionary limitsi
Fishing mortality in
relation to
precautionary limitsii
Fishing mortality in
relation to highest
yieldiii
Categoryiv Most
significant
threat
Sole (Solea solea)
Skagerrak, Kattegat and the North Sea
< 0,1
Full reproductive
capacity
Harvested sustainably
Appropriate
- -
European lobster (Homarus
gammarus)
< 0,1 - - - - -
Brill (Scophthalmus rhombus)
< 0,1 - - - - -
Atlantic wolffish (Anarhichas lupus)
< 0,1 - - - EN Not known
Common dab (Limanda limanda)
< 0,1 - - - - -
Lemon sole (Microstomus kitt)
< 0,1 - - - - -
European flat oyster (Ostrea edulis)
< 0,1 - - - - -
Blue mussel (Mytilus edulis)
< 0,1 - - - - -
Halibut (Hippoglossus hippoglossus) < 0,1 - - - EN High fishing
pressure
Cusk (Brosme brosme)
< 0,1 - - - - -
Grey gurnard (Eutrigla gurnardus)
< 0,1 - - - - -
Garfish (Belone belone)
< 0,1 - - - - -
28
i Spawning biomass (amount of adult fish) in relation to precautionary limits recommended by ICES. The category “Full reproductive capacity” means that the fish stock is in
a healthy state and that the spawning biomass is above the minimum level recommended by ICES. “Increased risk” means that the amount of adult fish is below the
recommended minimum level and that there is a risk that production is reduced. “Reduced reproductive capacity” means that the stock is depleted.
ii Fishing mortality in relation to precautionary limits recommended by ICES. The category “Harvested sustainably” means that the fishing pressure is under the maximum
level recommended by ICES. “Increased risk” means that the fishing pressure is higher than the recommended maximum level and could lead to depletion of the stock.
“Harvested unsustainably” means that the fishing pressure is much higher than the recommended maximum level and is likely to deplete the stock.
iii
Fishing mortality in relation to highest yield is a measure of the level of fishing pressure that will lead to a high yield in the long term. The category “Below target” means
that there is scope for more fishing to get a higher yield in the long term. “Appropriate” means that fishing pressure is at the right level to get the most fish from the stock in
the long term. “Overexploited” means that fishing pressure is too high and that more fish could be taken from the stock in the future if fishing pressure was reduced.
iv A species is Critically Endangered (CR) when it is considered to be facing an extremely high risk of extinction in the wild. A species is categorized as Endangered (EN)
when it is considered to be facing a very high risk of extinction in the wild. A species is Vulnerable (VU) when it is considered to be facing a high risk of extinction in the
wild. A species is categorized as Near Threatened (NT) when it is close to qualifying for or is likely to qualify for a threatened category in the near future.
29
Appendix II
Table 2. Environmental impact of commercial fisheries for 25 seafood target species in areas where Swedish fisheries operate (Ziegler, 2008). The environmental
impact assessment include status and management of target species, size and species selection of fishing gear, seafloor impact, energy consumption, ghost-fishing and
catch quality.
Target species Fishing gear Fishing area Environmental impact
Status and
management of
fishing stocksv
(2-20)
Size
selectionvi
(1-10)
Species
selection
(1-10)
Seafloor
impact
(1-10)
Energy
efficiencyvii
(1-10)
Ghost-
fishing
(1-10)
Catch
qualityviii
(1-10)
Sum
(8-80)
Angler (Lophius
piscatorius)
Gillnet Northeast Atlantic 16 3 5 4 4 9 7 48
Bottom trawl Northeast Atlantic 16 7 8 9 10 2 6 58
Bottom trawl
(BACOMA)
Baltic Sea 16 3 6 9 10 2 5 51
Atlantic wolffish
(Anarhichas lupus)
Gillnet Northeast Atlantic 18 3 5 4 4 9 4 47
Longline Northeast Atlantic 18 4 5 2 5 3 2 39
Brown crab (Cancer
pagurus)
Creel Northeast Atlantic 2 1 4 3 7 5 1 23
Cod (Gadus morhua)
Bottom trawl
(BACOMA)
Baltic Sea 20 3 6 9 10 2 5 55
Gillnet Skagerrak, Kattegat and
the Baltic Sea
20 3 5 4 4 9 7 52
Bottom trawl Norwegian Sea 8 7 8 9 9 2 6 49
Longline Norwegian Sea 8 4 5 2 4 3 2 28
Danish seine Skagerrak and Kattegat 20 3 7 6 5 2 3 46
Bottom trawl with
sorting grid
Norwegian Sea 8 5 8 9 9 2 5 46
30
Target species Fishing gear Fishing area Environmental impact
Status and
management of
fishing stocksv
(2-20)
Size
selectionvi
(1-10)
Species
selection
(1-10)
Seafloor
impact
(1-10)
Energy
efficiencyvii
(1-10)
Ghost-
fishing
(1-10)
Catch
qualityviii
(1-10)
Sum
(8-80)
Bottom trawl Skagerrak and Kattegat 20 7 8 9 10 2 6 62
Bottom trawl with
sorting grid
Skagerrak and Kattegat 20 5 8 9 10 2 5 59
Common ling (Molva
molva)
Gillnet Northeast Atlantic 18 3 5 4 4 9 7 50
Bottom trawl Northeast Atlantic 18 7 8 9 10 2 6 60
Longline
Northeast Atlantic 18 4 5 2 5 3 2 39
European eel
(Anguilla anguilla)
Fyke net Skagerrak and Kattegat 20 3 9 3 8 7 2 52
Gillnet
Baltic Sea 20 3 9 4 4 9 7 66
European flounder
(Platichthys flesus)
Gillnet Baltic Sea 2 3 5 4 3 9 7 33
Bottom trawl Baltic Sea 2 7 8 9 9 2 6 43
European hake
(Merlucchius
merlucchius)
Bottom trawl Northeast Atlantic,
northern stock
6 7 8 9 8 9 6 53
Gillnet/ Longline Northeast Atlantic,
southern stock
18 3 5 3 6 7 7 49
European lobster
(Homarus
gammarus)
Creel Skagerrak and Kattegat 6 2 2 2 7 5 1 25
European plaice
(Pleuronectes
platessa)
Beam trawl North Sea 12 9 9 10 10 2 7 59
Danish seine Skagerrak and Kattegat 6 3 7 6 5 2 3 32
Bottom trawl
Skagerrak and Kattegat 6 7 8 9 9 2 6 47
31
Target species Fishing gear Fishing area Environmental impact
Status and
management of
fishing stocksv
(2-20)
Size
selectionvi
(1-10)
Species
selection
(1-10)
Seafloor
impact
(1-10)
Energy
efficiencyvii
(1-10)
Ghost-
fishing
(1-10)
Catch
qualityviii
(1-10)
Sum
(8-80)
European sprat
(Sprattus sprattus)
Purse seine Northeast Atlantic 2 5 6 2 2 1 2 20
Haddock
(Melanogrammus
aeglefinus)
Danish seine Northeast Atlantic 4 3 7 6 5 2 3 30
Bottom trawl Northeast Atlantic 4 7 8 9 9 2 6 45
Bottom trawl with
sorting grid
Northeast Atlantic 4 5 8 9 9 2 5 42
Halibut
(Hippoglossus
hippoglossus)
Gillnet Northeast Atlantic 20 3 5 4 4 9 7 52
Bottom trawl Northeast Atlantic 20 7 8 9 10 2 6 62
Herring (Clupea
harengus)
Pelagic trawl Northeast Atlantic 2 5 6 1 4 2 3 23
Purse seine Northeast Atlantic 2 5 6 2 2 1 2 20
Pelagic trawl Baltic Sea 2 5 6 1 3 2 3 22
Purse seine
Baltic Sea 2 5 6 2 1 1 2 19
Lemon sole
(Microstomus kitt)
Bottom trawl Northeast Atlantic 12 7 8 9 9 2 6 53
Mackerel (Scomber
scombrus)
Pelagic trawl Northeast Atlantic 16 5 6 1 4 2 3 37
Maraene (Coregonus
maraena)
Gillnet, fyke net,
fish trap
Baltic Sea ? 3 5 4 3 9 2 ?
Gillnet Vättern 16 3 5 4 4 9 7 48
Gillnet
Other Swedish lakes 2 3 5 4 3 9 2 28
32
Target species Fishing gear Fishing area Environmental impact
Status and
management of
fishing stocksv
(2-20)
Size
selectionvi
(1-10)
Species
selection
(1-10)
Seafloor
impact
(1-10)
Energy
efficiencyvii
(1-10)
Ghost-
fishing
(1-10)
Catch
qualityviii
(1-10)
Sum
(8-80)
Northern shrimp
(Pandalus borealis)
Shrimp trawl with
sorting grid
Northeast Atlantic 2 7 4 8 9 2 5 37
Shrimp trawl with
sorting grid
Northeast Atlantic 2 7 9 8 9 2 6 43
Norway lobster
(Nephrops
norvegicus)
Lobster trawl with
sorting grid
Skagerrak, Kattegat and
the North Sea
2 7 4 9 9 2 5 38
Creel Skagerrak 2 3 2 3 7 5 1 23
Lobster trawl Skagerrak, Kattegat and
the North Sea
2 7 9 9 9 2 6 44
Perch (Perca
fluviatilis)
Gillnet Baltic Sea and Swedish
lakes
2 3 4 1 3 9 9 31
Pikeperch (Sander
lucioperca)
Gillnet/fyke net Hjälmaren 2 3 4 3 3 9 2 26
Gillnet/fyke net Other Swedish lakes 4 3 4 3 3 9 2 28
Saithe (Pollachius
virens)
Gillnet Northeast Atlantic 2 3 5 4 3 9 7 33
Danish seine Northeast Atlantic 2 3 7 6 5 2 3 28
Bottom trawl Northeast Atlantic 2 7 8 9 9 2 6 43
Bottom trawl with
sorting grid
Northeast Atlantic 2 5 8 9 9 2 5 40
Salmon (Salmo salar)
Gillnet Sweden 18 3 5 3 6 7 7 49
Sole (Solea solea)
Gillnet North Sea 2 7 8 4 3 9 7 40
33
Target species Fishing gear Fishing area Environmental impact
Status and
management of
fishing stocksv
(2-20)
Size
selectionvi
(1-10)
Species
selection
(1-10)
Seafloor
impact
(1-10)
Energy
efficiencyvii
(1-10)
Ghost-
fishing
(1-10)
Catch
qualityviii
(1-10)
Sum
(8-80)
Spiny dogfish
(Squalus acanthias)
Gillnet Northeast Atlantic 20 3 5 4 4 9 7 52
Turbot (Psetta
maxima)
Gillnet Baltic Sea 10 7 5 4 4 9 7 46
Whiting (Merlangius
merlangus)
Bottom trawl Northeast Atlantic 12 7 8 9 9 2 6 53
Bottom trawl with
sorting grid
Northeast Atlantic 12 5 8 9 9 2 5 50
Witch
(Glyptocephalus
cynoglossus)
Bottom trawl Northeast Atlantic 12 7 8 9 9 2 6 53
Danish seine Northeast Atlantic 12 3 7 6 5 2 3 38
Cusk (Brosme
brosme)
Longline Northeast Atlantic ? 4 5 2 4 3 2 ?
v The environmental impact assessment is based on the amount of biological knowledge about the stocks, occurrence of illegal fishing, stock assessments by ICES and other
organizations as well as management plans. The environmental impact is presented on a scale ranging from 2-20 where 20 stands for the highest impact.
vi The environmental impact assessment is based on the selectivity of the used fishing gear and fishing method and on the survival rate of discards. The environmental impact
is presented on a scale ranging from 1-10 where 10 stands for the highest impact.
vii The energy efficiency assessment is based on available LCA studies, stock assessments and the distance between the fisheries and Sweden.
viii The environmental impact assessment is based on fishing methods and the sensibility of target species.