The Common, European or Sea Sturgeon Acipenser sturio has been recently regarded as an occasional visitor to the UK, rather than as a native species. This may be far from true.
A deep dive into the historical ecology of sturgeon is shedding new light on how the magnificent fish used our rivers, estuaries, and coastal waters. The species has a similar life cycle to salmon, but with important differences. 5-10% of the adult stock stray to new rivers to spawn. Young fish descend to the estuary and spend up to 10 yrs there as adolescents, sometimes moving to a distant estuary before maturing. The fish can live for 100 yrs and can grow to 600kg!
Since the advent of newspapers in 1700, we have been able to source over 1,400 records of sturgeon entering UK rivers, mostly in the summer and often in small groups, both indicative spawning behaviours. Some of the larger females were reported to be "full of ova” and even “dripping eggs” when taken from the water. There is only a little evidence of successful spawning in the UK so far. We are looking back further into the archaeological record for more.
The newspaper reports demonstrate that the fish were persecuted in our rivers. The few that got past the efficient salmon nets in the estuaries faced an onslaught from fishermen, anglers, and others who used pitchforks, nets, harpoons and even guns to remove these “unwanted sea monsters” from their rivers! Noting this persecution, Francis Francis said in a letter to the Times in 1879, “if we just left these few fish alone, we might actually have a breeding population!”
This is a highly visible fish moving slowly upstream on the surface towards spawning gravels in the non-tidal lower freshwater reaches. Like so many other freshwater species, Sturgeon are highly vulnerable to man’s impacts.
Large scale fish traps spanning half of the river channel from the Bronze Age to the 7th century Saxon period have been reported from the Thames and elsewhere. Sturgeon bones and scutes have been found in riverside middens. Over-fishing in rivers was a concern across Europe by the 11th century and by the 12th century the species was in decline throughout its range. Magna Carta (1215) and other contemporary documents describe the urgent need to reduce the numbers of “fixed fishing stations” in rivers. In 1289 King Philip IV introduced the country’s first fisheries ordinance over excessive fishing in French rivers.
In addition, because of their size and swimming ability, they have limited capacity to get past obstructions in waterways. Water mills have existed here since the 7th century. From the 9th century to the Domesday Book (1086) grain mills along English rivers grew from 200 to 5,624 and rose above 10,000 by 1300. Locks and weirs to improve navigation began in the Middle Ages, with significant expansion in Tudor times, and on the Severn in the mid 19th century. These effectively cut off sturgeon from potential spawning grounds.
There are 3,600 plus records since 1700 from our coastal waters showing patterns of seasonal movements and aggregation areas. As commercial fisheries in Germany on the River Elbe crashed through over-exploitation around 1900, British skippers hunted down the last groups on the Dogger Bank and off Denmark and then sold individual large sturgeon at 3m plus to German buyers for the equivalent today of £2,750 each! Not for caviar but for smoked sturgeon for the German aristocracy.
Restoration programmes are now underway in France and Germany. Several tagged adolescent sturgeon from these sources appeared in the Bristol Channel and off the South Coast in the early 1990’s. Six more have appeared off the South Coast and West Wales in the last 4 yrs, with many more projected to follow, given the known straying habit.
The closely related Baltic or Atlantic Sturgeon A oxyrinchus has also visited our waters in the past and today. The UK is the only European country where both species can be found.
All sturgeon captured in freshwaters and within 3 miles of the coast are the property of the Crown, established as part of the Royal Prerogative by Edward II in 1324. The Crown have not accepted a fish since 1969. Today the Common Sturgeon is listed internationally under the Bonn and Bern Conventions, CITES, Ramsar, IUCN Red List, Rio Convention on Biological Diversity, OSPAR and the Habitats Directive. At the UK level under the Wildlife& Countryside Act, 1981 and UK BAP priority species list (2007).
Under General Licence other species of sturgeon can be introduced to private ponds as ornamental fish. Unfortunately, these fish have been stocked out illegally to a number of Stillwater fisheries since the mid-1990’s. Some have washed out into rivers during floods and yet more have been illegally released to the wild by pond keepers surprised by the size of their pets! Issues such as exotic diseases and competition applies to all non-native introductions, but with sturgeons there is an additional risk. Most can successfully hybridize. This threatens restoration of the native species across Europe given the migrations of these species.
In late 2019, the Institute of Fisheries Management, Blue Marine Foundation, ZSL, Severn Rivers Trust and Nature at Work founded the UK Sturgeon Alliance to work proactively with a wide interest group, the general public, regulators, government and overseas experts to champion the cause of this 200 million year-old living fossil. Ultimately, we want to see self-sustaining populations of sturgeon in our waters once more. This is truly a Pan-European challenge for species that know no boundaries. Early work will centre on developing awareness of both native and non-native species.
Fully 15% of those 1,400 river records come from the Severn and tributaries and so the Alliance is working alongside our partnership project, Unlocking the Severn, which is looking at easing passage for migratory species such as the Twaite Shad Alosa fallax. We are also already working with communities along the river about native fish reintroduction and a wonderful legacy from Unlocking the Severn may well see the return of this incredible species to the Severn.
If you catch a sturgeon in a river please take a photograph and return it to the water. We have experts who can identify the species from good photograph. If you catch one at sea, here is a helpful page which provides good advice, see - https://www.gov.uk/guidance/protection-of-common-sturgeon-advice-for-fishermen.
Ours is a community based approach where individuals can make positive contributions. If you want to help or get more information, please do get in touch.
Article adapted from Steve Colclough BSc (Hons), FIFM, C.Env. Chair, Estuarine and Marine Waters Section, Institute of Fisheries Management.