Allis and Twaite Shad

  • Scientific names: Alosa alosa (Allis Shad) and Alosa fallax (Twaite Shad)
  • Also known as: May Fish
  • Size: Up to 20ins/50cm in length and 4lb. UK shore caught typically 25cm and under 1lb.
  • UK minimum size: N/a – See below.
  • UK shore caught record: Allis Shad 4lb 12oz / Twaite Shad 2lb 12oz [UK record currently suspended due to Endangered status].
  • IUCN status: LC (Least Concern) (but see below)
  • Distribution: Migrates between freshwater and saltwater throughout Europe.
  • Feeds on: Plankton and tiny invertebrates when young, eats small crustaceans and hunts small fish when older.
  • Description: Small, herring like fish. There is a single dorsal fin and a deeply forked tail. Silvery appearance which can be darker on the back and fins. Scales are loose and very large. Spot pattern runs along flanks from gill covers, although this varies vastly between individual fish – in some fish fifteen spots can run all the way to the tail, in others the spots can be absent altogether.
  • Additional notes: Not to be confused with Scad. Shads are also a type of fishing lure.

Two Species – Allis and Twaite Shad

The two species of shad found in UK waters are the allis shad (Alosa alosa) and the twaite shad (Alosa fallax). These two species are very similar, with the main difference being the size (allis shad can grow to almost 5lb, twaite shad just to 2lbs). The only other differences are that allis shad have more than seventy scales along the lateral line and more than ninety gill rakers, whereas twaite shad have less than seventy scales along the lateral line and fewer gill rakers. The dark spots on the flanks and tail vary within and between species meaning they cannot be used for identification purposes. The two species can also interbreed, meaning that some shad exist which have numbers of lateral line scales and gill rakers between the figures mentioned above. Due to the close similarities between these species and the fact that anglers are unlikely to be able to tell shad species apart the rest of this article will consider shad as a single species.

Distribution and Life Cycle

Shad are members of the Clupeidae family and are closely related to herrings. They are a European species, found from the Baltic Sea to the Mediterranean. A small population is listed by some sources as being present off the coast of North Africa, although they may now be regionally extinct in this area. They are an anadromous fish meaning they can live in both salt and freshwater environments. Mature shad spend their life in the sea, where they feed on small fish such as sprats, lesser sandeel and other small fish. In spring (usually in the month of May, hence the alternative name of May fish) shad migrate up rivers and into freshwater to breed. Shad can travel hundreds of miles inland before they find their spawning grounds. The young shad live in freshwater for some time before they begin to make their way back downstream and towards the sea. Usually, shad will have reached the sea by the time they are two years old and live in saltwater until they reach sexual maturity at any time between the age of three and seven. Allis shad can only reproduce once and die after breeding, whereas twaite shad can carry out the journey and reproduce multiple times.

Endangered Status of the Shad

River Wye Estuary
The River Wye is one of the few remaining rivers where the shad still migrates and breeds.

Shad numbers are massively reduced in Britain compared to several decades ago. Overfishing has played a part. Although shad had not been a food fish in Britain since the 1800s it is still caught and disposed of as bycatch. However, the biggest cause of the reduction of shad numbers is obstructions built into rivers such as dams, sluices, weirs and pumping stations. These structures have disrupted migratory patterns of shad and been the major cause of decimated shad numbers. A further problem is that these structures are often created to be ‘fish friendly’ and are passable by trout and salmon but cannot be passed by the smaller and weaker shad. Shad also need clean and clear water and pollution caused by industry has played a part in reducing numbers. Today shad are absent from many areas where they were once abundant. Many major European rivers such as the Rhine, Elbe and Thames are now devoid of shad and they are no longer found in landlocked European countries where they used to be present during their migrations along rivers. The rivers Usk, Wye and the River Severn are rare UK rivers where shad are known to spawn, but only remnant populations remain in other major rivers where the shad used to be common.

There is some good news for this species. The north west of France remains something of a stronghold for shad, being one of the last areas of Europe where this species can be found in reasonable numbers. In the UK it has been reported that over the last decade shad appear to be slowly increasing in numbers in areas such as the Tamar Estuary. There have also been initiatives that aim to remove or redevelop barriers to allow shad to freely migrate up rivers. The Unlocking the Severn project, which is a collaboration between the Canal and River Trust, Severn Rivers Trust, the Environment Agency and Natural England, is one of the most prominent of these and seeks to reopen 150 miles of the Severn for shad. If projects such as these are successful then there is every chance that shad could begin to make a recovery both in British waters and throughout Europe.

International Union for the Conservation of Nature Status

The IUCN (International Union for the Conservation of Nature) currently still classes the shad species as one of Least Concern – the category used for species which are not threatened and are abundant. This assessment, however, dates back to 2008 and when a new analysis is carried out it will inevitably reflect the decline in shad numbers across its range. Some research by the IUCN does show the huge reduction of the abundance of this species. The IUCN class the shad as Regionally Extinct in Northern Africa and also class it as extinct in the Czech Republic and Switzerland, both countries where the shad used to be found during its freshwater migrations.

Legal Protection for Shad

Twaite shad caught by angler
Twaite shad caught by angler. All shad must be returned to the water as quickly as possible under UK law.

Rod and line anglers who catch shad in the UK usually do so when they are using spinners to catch bass, or feathers and daylights to target mackerel, although it is possible to catch shad with bait.  Due to the rarity of this species, the shad is subject to substantial legal protection. It is illegal to kill, injure or take a shad from the sea under Section 5 of the Wildlife and Countryside Act (1981). It is therefore not legal to specifically target shad and any shad inadvertently caught must be returned to the sea immediately without injury or harm. Shad are also protected by Chapter III of the Bern Convention, the legally binding regulation which protects endangered flora and fauna across Europe.

Rod and Line Caught Records

Due to their legal protection and the fact that both species of shad must be returned to the sea if they are inadvertently caught it is not possible to claim a British record for catching this species. The records which have previously been set (when it was legal to retain shad) still stand. Allis shad have a British shore caught record of 4lb 12oz which was set by P. Gerrard off Chesil Beach, Dorset in 1977. These is no boat caught record listed for this species. Twaite shad have a shore caught record of 2lb 12oz set by J. Martin fishing from Garlieston, Scotland in 1978. The boat caught record for twaite shad is a specimen of 2lb 4oz caught by D. Protheroe fishing off Barry, Wales in 1985. The International Game Fish Association also list the all-tackle world records for these species. The IGFA record for allis shad is a fish of 5lb 2oz caught by Samuel Davis on the Aulne River at Chateaulin, France in 2005 and the twaite shad record is set at 1lb 8oz as is listed as being caught in the North Sea, Netherlands by P. C. Ouwendijk in 1998.