‘Freshwater fish’ are present in all types of water bodies, ranging from small dystrophic pools in our upland areas and moors, to large rivers and lochs. In order to survive in these disparate habitats, members of the Scottish freshwater fish community have evolved a remarkable range of life-history strategies. For example, some of these fish elect to spend their entire life in freshwater, whilst others migrate between freshwater habitats and the sea. Some of these species have evolved in ways which Darwin himself would be astounded.
- 1 About freshwater fish
- 2 Atlantic salmon
- 3 Vendace and powan: the coregonids
- 4 Sparling
- 5 Sticklebacks
- 6 Lampreys
- 7 Arctic charr
- 8 European eel
- 9 The Shads – Twaite and Allis
- 10 Other freshwater fish
About freshwater fish
An important role
Freshwater fish play an important role in Scottish society and the fisheries, and particularly angling, opportunities that they provide have supported rural communities for many years. That said, however, the native fish fauna of Scotland is considered to be impoverished when compared to that found in other parts of the UK and Europe. Most of the fish which originally colonised Scottish freshwaters did so from the sea, occupying and using new freshwater environments as the ice sheet which covers Scotland 10-15,000 years ago retreated northwards at the end of the last ice age. All of the species that we now regard as conservation priorities within Scotland, such as lamprey, Atlantic salmon, trout, Arctic charr, powan, vendace, smelt (sparling), shad and eels, all colonised Scotland in this way. Both three-spined and nine-spined sticklebacks also used this marine route to invade Scottish freshwater habitats, and some of these populations, particularly those containing spine-deficient forms, are also considered to be of conservation value. Another species worthy of mention is the Atlantic sturgeon, a species rarely seen in Scottish waters, but still considered to be part of our native fauna.
How they got here
Some other species commonly seen in our lochs and large rivers, such as pike, perch, roach, minnow and stone loach may have arrived here via the land bridge that once connected rivers in the south east of England with continental Europe. Man has, however, played the most significant role in the spread of new fish populations around Scotland. Most of these translocations, or introductions, were carried out in an attempt to establish new sport fisheries, or in some cases to provide fish for food. Some of these fish, such as perch, roach grayling and pike, now support a significant, and growing, fishery resource.
The problem with some introductions
Other fish translocations from other parts of the UK have, however, caused considerable damage to either the Scottish freshwater fish fauna, or their habitats. The introduction of ruffe to Loch Lomond is the most cited example, and this species, which feeds on the eggs of powan, is now firmly established there. New controls to regulate the introduction of freshwater fish will hopefully ensure that such introductions do not take place in future.
Some of our now ‘resident’ fish fauna has come from further afield. The widespread use of rainbow trout, introduced from North America in the 1970s’, has led to the development of a significant, and valuable, fishery for this species. Other species, such as the brook charr have also been introduced to a small number of Scottish sites and, unlike rainbow trout, have established self-sustaining populations.
Scotland has a fish fauna which, despite the relatively low number of species, is both incredibly diverse and located at the western limits of their European geographical range. Some species, such as the Arctic charr, show remarkable levels ‘hidden biodiversity’ and Atlantic salmon which exhibit a wide range of life-history patterns, as well as supporting a world class fishery are of particular note. We hope that you take the time to learn more about our lesser known, but still incredibly important, fish species.
How long do they spend at sea and in freshwater?
Eggs are laid by female fish in gravel depressions called “redds”. As the eggs are released by the female, they are immediately fertilised by an accompanying adult male, and often by mature juvenile males (often referred to as ‘precocious’ parr). The fertilised eggs are then covered with gravel by the female. Spawning occurs between November-December but in some localities, particularly in larger rivers, this may extend from October – late February. After spawning has taken place about 90-95% of all Atlantic salmon die. Some do, however, survive and some may spawn twice or more.
The time taken for eggs to hatch (or the ‘incubation time’) depends on the water temperature. Generally speaking, eggs usually hatch during early spring. These young fish, which still have a yolk sac attached, are called ‘alevins’. These fish remain in the redd for a few weeks and emerge from the gravel in April or May, when they have absorbed the yolk sac and are about 3 cm in length. These fish establish territories and compete with each other to feed on a range of items within the stream. As these ‘fry’ get larger, they develop prominent markings on their sides and are then known as ‘parr’. Depending on the water temperature and the availability of food, these fish will live in the river for two to three years. Once they reach a size of ~12 cm, the parr undergo a physiological transformation which allows them to survive in marine environments. The young fish, now called “smolts”, change in physical appearance, becoming silver, and start to leave the rivers during the late spring. Most of these fish will be gone by June.
Where do the smolts go and how long do salmon spend at sea?
Relatively little is known about the migration pathways of post-smolts or returning adults. Some research has shown that post-smolts move in schools whilst heading off to deep-sea feeding areas. Some of these fish feed in the Norwegian Sea and the waters off Southwest Greenland, and they may also utilise other sub-arctic feeding areas.
These fish remain in the ocean from just over a year to three or four years. Fish which spend only one year at sea (usually around the Faroe Islands and the southern Norwegian Sea) before coming back to Scottish rivers are called grilse at a size of 2-3 kg. Other fish may stay at sea for two or three years before coming back to Scotland. These are referred to as Multi-Sea-Winter fish or ‘salmon‘ and, because they have spent more time feeding in marine environments (usually off Greenland) are larger than grilse. If these fish return to Scottish rivers between the months of January-June, they are referred to as ‘spring salmon’. Salmon may, of course, enter Scotland’s rivers at all times of the year. This contrasts with the migratory patterns observed elsewhere for this species within their global range and is one of the factors that make Scottish populations so important from a biodiversity perspective.
Atlantic salmon conservation status
Atlantic salmon are listed on Appendix III of the Bern Convention and Annex II and V of the EC Habitats & Species Directive. The multi-sea-winter component of the Atlantic salmon population is included in the UK Biodiversity Action Plan Priority Species List.
Vendace and powan: the coregonids
Vendace and Powan comprise a group known as the ‘Coregonids’. Two species of coregonid are located within mainland Britain – Coregonus albula (vendace) and Coregonus lavaretus (known as powan in Scotland, schelly in England and gwyniad in Wales). Another species Coregonus autumnalis (known as pollan) is restricted to Irish waters.
Vendace – the rarest freshwater fish in Britain
Vendace, has a more restricted distribution than powan and until recently they currently found in only two lakes within mainland Britain. Both of these lakes, Bassenthwaite and Derwentwater are located within the English Lake District. In 2008 surveys concluded that the Bassenthwaite population was extinct.
Populations of this species used to occur in two locations in Scotland, Mill Loch and Castle Loch, but these are now also considered to be extinct. In the mid-1990’s, fish from Bassenthwaite and Derwentwater were translocated to two waterbodies in the Scottish Borders, Loch Skeen and Daer Reservoir. These waterbodies were carefully selected from a number of other locations on the basis of their bathymetry, water chemistry, availability of spawning substrate and the presence of other fish species. The success of this attempt to re-establish vendace in Scotland and to safeguard the two existing English populations has recently been assessed. The vendace which were introduced into Loch Skeen from Bassenthwaite have become established there. The introduction of fish from Derwentwater to Daer Reservoir may not, unfortunately, have succeeded.
Powan – an ice-age relict
Powan are more widespread within the British Isles than vendace, but natural populations of this species are still restricted to just seven locations. In Scotland, natural powan distribution is restricted to Loch Eck and Loch Lomond. However, fish from Loch Lomond were transplanted to two other locations Loch Sloy and the Carron Valley Reservoir and have become established there. In Wales the distribution of powan is restricted to just one lake, Llyn Tegid. Attempts have been made to establish refuge populations of powan from Llyn Tegid. The English Lake District appears to be the stronghold for powan within the British Isles and this species is found in Ullswater, Haweswater, Red Tarn and Brotherswater. A translocation of powan from Haweswater to Small Water in 1997 has recently resulted in the establishment of a new breeding population there.
Vendace and powan habitat requirements
Both vendace and powan are commonly associated with deep, cool, well oxygenated lochs. In keeping with their environmental requirements, the distribution of these populations within the British Isles is polarised towards cool, mesotrophic and oligotrophic lakes in upland areas.
Challenges for vendace and powan
Recent attempts to translocate the most vulnerable populations has laid testimony to the fact that both species now face considerable challenges if they are to survive. They are highly susceptible to declines in water quality, increased siltation and de-oxygenation. Drawdown regimes for hydroelectricity of potable water also problematic if the species is present in reservoirs. The introduction of alien species, such as Ruffe, can also lead to population declines, or even loss.
Vendace and powan conservation status
Both vendace and powan are protected under Schedule 5 of the Wildlife & Countryside Act 1981 (as amended) and are listed on Appendix III of the Bern Convention; Annex Va of the EC Habitats & Species Directive and Schedule 3 of The Conservation (Natural Habitats, etc) Regulations 1994. Vendace also included in the Species Action Framework and appear in the UK Biodiversity Action Plan Priority Species list.
A tale of two names
Sparling, as they are known in Scotland, are referred to in other parts of its UK and European range as the European Smelt (Osmerus eperlanus).
Where can they be found?
Sparling occur around the western coasts of Europe (including the Baltic Sea) and its range extends as far south as Spain. This species is found in coastal waters and estuaries and migrates into large clean rivers to spawn.
Sparling was previously known to occur in a number of Scottish rivers and populations have been recorded as having occurred in the Rivers Almond, Annan, Bladnoch, Clyde, Cree, Dee, Esk, Fleet, Forth, Girvan, Lochar, Nith, Stinchar, Tay and Urr Unfortunately, sparling have now disappeared from almost all of these rivers, with the rivers Cree, Forth and Tay being notable exceptions.
Sparling habitat requirements
Adult sparling utilise estuarine environments and spawn in rivers. These fish use high spring tides between February-April to help move upstream, meaning that spawning activity is linked to the lunar cycle. Once in the river, sparling spawn, near the tidal limit, on gravel, cobble, boulders and vegetation in rivers. Spawning happens pretty quickly and in some years, spawning events can be difficult to detect. The eggs adhere to these substrates and, to hatch successfully, the eggs require good quality, well oxygenated water. Most fish die after spawning takes place, although some survive to spawn again. After hatching, juvenile sparling move back to estuaries to feed and grow before returning, as adults, to spawn.
Pressures on sparling
Sparling populations are highly susceptible to deterioration in water quality (particularly siltation). They are poor swimmers and in-stream barriers to migration or increased river discharge (spates) can have a negative impact on spawning success. Sparling are, because of their spawning behaviour, relatively easy to catch in large quantities. As a result, this species has been heavily exploited in the past, and overexploitation has been blamed for the loss of some populations.
The conservation status of sparling
Sparling are a conservation feature in two Sites of Special Scientific Interest in Scotland, giving them protection under the Wildlife & Countryside Act 1981 (as amended). It is also included in the UK Biodiversity Action Plan Priority Species list.
Sticklebacks can be found in a variety of disparate habitats within the temperate and arctic zones of North America, Asia and Europe. As their name suggests, sticklebacks are laterally depressed with well developed dorsal and pelvic spines. The body may be covered with a variable number of boney plates (or scutes), and these may, in some instances, be absent. Spineless sticklebacks occur in calcium deficient systems and the loss of spines may also be an evolutionary adaptation to reduced predation risk.
The British spineless stickleback morphs are referred to as ‘anomalous’. These fish have no pelvic spines, a varying number of dorsal spines and often no pelvic girdle. Sticklebacks within the ‘anomolous‘ clade occur in: Southern and Northern extremes of the European distribution of the species; Pacific north west coast of the USA, on certain offshore islands of British Colombia Central and Southern California.
Within the British Isles, the distribution of spineless sticklebacks populations are restricted to the Western Isles and Northern Scotland.
The conservation status of spine-deficient sticklebacks
The ubiquitous nature of three-spine sticklebacks within the British Isles has meant that common forms have received no conservation status. Only those fish which display some degree of ecological or genetic divergence, such as the spineless morphotypes are considered to be of any conservation value. Spineless stickleback morphs are located in two SSSI’s in Scotland, Loch Ruthven (East Highland) and Loch Druidibeg (Western Isles) – but not as designated features of these sites.
The nine-spined stickleback is the smallest freshwater fish in Britain. Unlike the three-spined variety, nine-spined sticklebacks are not widely distributed in Scottish freshwaters and is most commonly associated with slow moving waters in the south and western parts of the country. They can also be found in some coastal and estuarine environments.
This is a poorly studied species and despite its apparent restricted distribution within Scotland and other parts of Britain, it is not considered to be under threat.
The lampreys belong to an ancient order of vertebrates, the Agnathans or ‘jawless fishes’. The skeletons of lampreys are of strong flexible cartilage and it is no comprised of bone. A round, sucker-like disc surrounds the mouth which, in adults, carries rasping teeth. Most, but not all, species of lamprey are parasitic on other fish. Lampreys occur in temperate waters in both the northern and southern hemispheres. The three lamprey species present in UK (brook lamprey Lampetra planeri, river lamprey Lamprey fluviatilis and sea lamprey Petromyzon marinus)
Brook lampreys are an entirely freshwater species, and unlike other British lamprey species, do not feed on as adults. They are the smaller of the British lamprey species, reaching a length of 15-19 cm. Despite being freshwater-resident, brook lamprey do, however, undergo limited spawning migrations. Some of these movements may be passive, such as the downstream drift of larvae to sandy/silt nursery areas. Here they remain for up to five years before metamorphosing into adults. Active upstream migrations of pre-adults and adults occur through the winter and, on reaching suitable gravel spawning areas, these fish hide among cover until spawning takes place during April-June. All of these adults die after spawning.
River lamprey are larger than brook lamprey, reaching a size of 30-50 cm. They are anadromous and migrate from their coastal feeding grounds into freshwater, to get ready to spawn, during the autumn and spring. Autumn migrants are sexually undeveloped while spring migrants enter from the sea in spawning condition. River lamprey migrate upstream at night and the adults rest in cover during the day. Spawning takes place between April-May on pebble/gravel substrates. Populations that are purely freshwater-resident are rare in Europe, but one exists in Scotland. This unique dwarf-river lamprey form is found in Loch Lomond. As its name suggests, this dwarf form is smaller than its sea-going conspecific, only reaching a size of 25 cm.
Sea lamprey are the largest of the three species, reaching a size of approximately one metre in length. After spending 18-24 months feeding at sea, adult sea lampreys migrate into rivers during the spring and early summer. They spawn between the months of May-July in areas of pebble and cobble substrate.
How do lamprey reproduce?
All lamprey species spawn in gravel substrates, not unlike those used by salmon and trout. Brook and river lampreys spawn slightly earlier than sea lamprey. On reaching their spawning ground, lamprey construct a ‘nest’ in which to lay their eggs – this is best described as a pit in the river and excavated material is piled up at the downstream end. Brook and river lamprey spawn in a ‘ball’ which may comprise up to 50 individuals. Sea lamprey, by contrast, spawn in much smaller numbers.
After hatching, the young lamprey larvae, known as ammocoetes, drift downstream with the current. These larvae settle in suitable areas of nursery habitat – areas that comprise fine, soft substrate in well oxygenated, slow flowing water. The ammocoetes feed on fine particulate matter such as diatoms, algae and bacteria. Ammocoetes may stay in this substrate for up to five years (or up to eight years for sea lamprey) before they transform into pre-adults and, in the case of river and sea lamprey, start their migration to the the sea during late autumn (sea lamprey) and late winter-early summer (river lamprey). Brook lamprey do not migrate to sea, spending their entire life in freshwater.
Are they threatened?
Good water and substrate quality (particularly in spawning areas) is important for all lamprey species, and all species are threatened throughout their range by habitat degradation. Physical barriers can pose particular risks to anadromous river and sea lamprey, but other freshwater-resident forms can be negatively impacted if new in-stream structures are created. There is no commercial value for brook lamprey, but in some areas of Europe, river and sea lamprey are exploited commercially for food. Historical fisheries existed for river lamprey in Britain, famously resulting in the death of an English monarch, but now, only one small-scale fishery exist for this species. These fish are used to supply the angling bait market.
The conservation status of lamprey
- Brook Lamprey Annex II of the EU Habitats Directive Appendix III of the Bern Convention.
- River Lamprey Annexes II and V of the EU Habitats Directive Appendix III of the Bern Convention and are on the UKBAP Priority List. The dwarf river lamprey form is a conservation feature in the Endrick Water Site of Special Scientific Interest in Scotland, giving it protection under the Wildlife & Countryside Act 1981 (as amended).
- Sea Lamprey Annex II of the EU Habitats Directive Appendix III of the Bern Convention and are on the UKBAP Priority List.
Despite their conservation status within Europe, sea lamprey are regarded as a serious non-native pest in the Great Lakes of North America. There, this species causes considerable damage to the sport fishery that exists there and millions of dollars are used to control sea lamprey numbers every year.
The Arctic charr, (Salvelinus alpinus), is closely related to two other native species: the Atlantic salmon and the brown trout. There is good evidence that Arctic charr were the first of the species to colonise the new post-glaciation freshwaters of Scotland it can be said that Arctic charr is the aboriginal freshwater fish species of Scotland. In Scotland, all known Arctic charr populations in Scotland are now freshwater-resident, however these have been derived from anadromous invaders which colonised these habitats as the ice receded. It is interesting to note that Arctic charr populations located at latitudes higher than 65o N continue to exhibit anadromous behaviour patterns when access to marine habitats are available. Populations at lower latitudes remain in freshwaters for their entire life-cycle.
Where are they found?
As its name suggests, the Arctic charr is a holarctic species which occurs in lakes and rivers throughout the northern hemisphere The most southerly natural populations in Europe are found at altitude in the Rhine and Danube catchments. They have, however, been introduced to many Alpine lakes and to lakes in the Pyrenees.
Arctic charr have the most northerly distribution of any freshwater fish and, in some northern latitudes the freshwater fish community is comprised entirely of this species. Globally there are thought to be around 50,000 populations of Arctic charr, most of these (~30,000) are located in Norway. The distribution of Arctic charr within the British Isles is polarised towards northern upland areas. Scotland is a stronghold for Arctic charr within the British Isles and 258 Scottish lochs are known to contain this species. Their distribution throughout the remainder of the British Isles is patchy, with 74 Irish populations and localised populations in north-west England (8) and north Wales (4).
What sort of habitats do they use?
In Scotland, there are no known populations that exhibit anadromy, although we cannot not rule out the possibility that this may occur. There are no known populations in Scotland which occupy rivers throughout their life cycle, however there some populations that are found there occasionally and a few populations are known to spawn in streams and rivers of systems which also contain standing waters. Thus the majority of Arctic charr populations in Scotland occupy standing waters.
Are they exploited?
There are no commercial or subsistence fisheries for Scottish Arctic charr populations and it is only rarely exploited for angling, except by a very small number of specialist anglers or where it is a by-catch for other salmonid species. This contrasts significantly with other countries, where there are both significant commercial and sport fisheries. Thus the evidence suggests that in comparison with other countries the Arctic charr populations of Scotland have not been substantively modified by between-population mixing. This means that, unlike many European populations, most Scottish Arctic charr populations are genetically pristine.
Status in Scotland and threats
Potential threats to Arctic charr include climate change, eutrophication, acidification, afforestation, lake engineering, exploitation, aquaculture, non-native species introductions and introductions of charr of different race, stock or type. In Scotland in contrast, the number of extinctions of populations in historical times, is relatively low (although it is likely that some populations became extinct before records were available). We know of a number of sites were Arctic charr have been lost, and there may be others where populations are on the brink of extinction. The majority of known extinctions are from south and central Scotland and at least five are thought to be due to acidification.
The Arctic charr ‘complex’ and the conservation conundrum
It has long been recognised that Arctic charr display an unusually high degree of variance in phenotype (i.e. physical characteristics). This variation manifests over a wide range of characteristics including: morphology, size, colouration, behaviour and life history. Considerable variation can take place between (allopatric) and within (sympatric) Arctic charr populations. Arctic charr can differ markedly between waterbodies, but in some lochs up to three genetically and morphologically different forms can be found. Each of these may exhibit different patterns of habitat use, spawning location and the timing of reproductive behaviour. These populations are therefore ‘reproductively isolated’ and this, in turn, leads the way to genetic divergence.
Such is the variation with Arctic charr populations within the British Isles that taxonomists in the early 20th century described the existence of 15 different ‘charr’ species – seven of which were present in Scotland. It is now accepted that these fish are all variants of one species, the Arctic charr S. alpinus. There have been recent moves by some individuals within the scientific community, however, to revise the taxonomy of Arctic charr and ‘split’ this species into a number of individual species units – based entirely on their morphology. This approach ignores evidence that Arctic charr in northern Europe are currently undergoing a period of very rapid evolutionary change resulting in a very significant adaptive radiation.
If this new taxonomy is accepted, the addition of an 12 new ‘species’ of charr to Scotland (with many more to come if the same approach is used in future years) will carry with it significant consequences for freshwater fish conservation both nationally, and internationally. It is clear that much further investigation, using genetic approaches, is required before this new, and potentially costly, taxonomy is accepted – not one which is based not only on the morphological characteristics of a rapidly evolving and phenotypically plastic species.
Current levels of protection
Currently, Arctic charr are a conservation feature in five Sites of Special Scientific Interest (Lochs Eck, Insh, Builg, Girlsta and Doon), they are also present in a number of waterbodies protected for other purposes, either under the Natura 2000 network or the National Nature Reserve series. The considerable conservation value of Arctic charr within the UK has been further recognised by their addition to the UKBAP Priority Species List in 2007.
The European eel has, perhaps, one of the most interesting life history patterns of all European freshwater fish.
What makes the eel life-cycle so interesting?
The migration of eels from the freshwater and estuarine waters of Europe to the Sargasso Sea, located to the south-west of Bermuda, is one of the most impressive feats of animal migration observed in nature. Although this migration is accepted as scientific fact, surprisingly little research has been carried out to determine whether this the only site used by European eels to reproduce. No silver eels, the migratory adult form, have ever been caught in the open ocean, and it is unclear whether spawning takes place at only one time of year or over an extended period. It is also unclear how long it takes eels take to get to their spawning grounds, and how many of the eels that leave Europe reach the Sargasso Sea to spawn.
After spawning, it is assumed that the eggs drift eastwards towards Europe with the Gulf Stream. During this time, the eggs hatch and the young larvae, now called leptocephalus, are ‘leaf’ shaped and it is only on reaching the European continental shelf that they metamorphose into the cylindrical shape that we associate with eels. These fish are virtually transparent and are called ‘glass eels’.
On entering freshwater, the glass eels start to change in colour and become darker as pigmentation takes place. They are now known as elvers. During this time, they migrate upstream and occupy a wide variety of freshwater and estuarine habitats, feeding on invertebrates and fish. Eels are also known to move overland, moving over wet terrain to get to some waterbodies. During their freshwater-resident phase they are known as yellow eels and they can remain in these habitats for more than 20 years. When eels are ready to reproduce, their colouration changes and they start to turn silver in preparation for their migration to the Sargasso Sea.
Are eels under threat?
All life stages of the European eel, glass, elver, yellow and silver, have been exploited by man for centuries and throughout Europe they have supported a number of large-scale commercial fisheries. Within Scotland, eels have not been heavily fished, but some limited exploitation has taken place in some localities. Although long-term datasets are few, it is clear that European eel have undergone a significant and drastic decline over the last two decades. It has been estimated that eel numbers have decline by over 90% during this period.
Are there conservation measures in place?
The widespread decline in European eels has led the European Commission has develop an Eel Recovery Plan (Council Regulation No 1100/2007). This plan aims to return the European eel stocks adults and glass eels) to sustainable levels. Each Member State is required to establish national Eel Management Plans. An Eel Management Plan for Scotland was developed by Marine Scotland Science in 2008.
The European eel was also added to the UKBAP Priority Species List in 2007.
The Shads – Twaite and Allis
Two species of shad occur in Scottish waters – the Twaite shad (Alosa fallax) and the Allis shad (Alosa alosa). So similar are they in physical appearance, that to anyone other than a specialist, it is very difficult to physically differentiate between these two species. This is made even more difficult because there is some suggestion that both species hybridise.
Are they truly freshwater species?
No – both species are anadromous, meaning that they live as adults in the sea, but migrate to freshwater to spawn between April-May. After spawning, and once the eggs have hatched, the juvenile fish migrate to sea over the next few months. These fish feed on a range of marine crustaceans and small fish before returning to the river to spawn 3-4 years later, after they reach maturity.
Where can they be found?
In the British Isles, both species are more commonly associated with the south-western coastline, and, in particular, the rivers Severn, Usk and Wye. In Scotland, they are more commonly associated with the Solway Estuary, although little is known about their adult distribution and spawning sites. Within Europe, shad are present in coastal environments throughout extending from southern Norway southwards towards the eastern Mediterranean.
Are they under threat?
Both species spawn on rocky river substrates and require good quality, well oxygenated rivers to allow the eggs to survive. Water quality and access to suitable spawning areas is therefore a significant issue for these fish. Shad were previously exploited for food and, in other parts of its British and European range, both Twaite and Allis shad supported a number of commercial fisheries. Although it is now illegal to fish for shad in Britain, some continental European fisheries still remain in operation.
What is their conservation status?
Both Twaite and Allis shad are protected via Schedule 5 of the Wildlife & Countryside Act 1981, and are listed on Annexes II and V of the EU Habitats Directive. They are also contained in Appendix III of the Bern Convention and are on the UKBAP Priority List.
Other freshwater fish
Common sturgeon are a species that are, because of the presence of bony armour and prehistoric-type appearance, instantly recognisable by all. It is also a species that can attain a large size – extending to over 3 metres in length and weighing over 200 kg. Sturgeon, which can live for up to 50 years, is native to much of western Europe as well as the Mediterranean, Baltic and the Black Seas. It is known to spawn in large rivers, but has never been known to reproduce in British waters and remains the only sturgeon species to have been caught here.
Are sturgeon under threat?
Sturgeon were one heavily exploited within Europe, both for caviar (sturgeon eggs or roe), and their flesh. Here, this species is perhaps known for the fact that, in the British Isles, all sturgeon captured by the public must be offered to the reigning monarch. What is less well known, however, is that the sturgeon is one of Europe’s most threatened fish.
Are they protected?
The rarity of common sturgeon in the British Isles is reflected by the fact that it is present on both Schedule 5 of the Wildlife & Countryside Act 1981 (as amended), and the UKBAP Priority Species List. At the European level, sturgeon are listed in Annexes II and V of the EU Habitats Directive and Appendix II of the Bern Convention. From a global perspective, common sturgeon are also considered to be critically endangered by the IUCN and trade in this species is regulated by CITES.
This species has been present in Scotland for ~150 years, although it is only truly native to England, and possibly parts of Wales. They are typically found in rivers which support trout and have similar habitat quality requirements. They are, however, found in at least two standing waters – the Gouthwaite Reservoir in England and Llyn Tegid in north Wales. Grayling attract much attention from both scientists and anglers and some research is supported by The Grayling Society .
Are they protected?
From a conservation perspective, European grayling are protected from over exploitation through their inclusion in Annex V of the EU Habitats Directive and Appendix III of the Bern Convention.