Twaite shad

Twaite shad share the allis shad's problem and have solved it slightly better, which is why they are the shad a British angler actually meets.

ADULTS LIVE AT SEA AND IN ESTUARIES, feeding on small fish and zooplankton in coastal waters. Several European populations have gone further and become permanently landlocked or estuarine, in Italian and Irish lakes among others — an adaptation allis shad has not made to the same extent.

SPAWNING REQUIRES GRAVEL IN MODERATE FLOW, reached by ascending a river in spring. In Britain the principal runs are in the Severn system: the Severn itself, the Wye, the Usk and the Teme.

THE SEVERN RUN IS THE THING TO UNDERSTAND. Shad ascend in late spring, and where they meet an obstruction they concentrate below it in numbers that are visible and audible. That concentration is not a feature of the fishery; it is the fish being stopped.

BECAUSE A SHAD CANNOT LEAP. This is the single most important fact about the species' habitat requirement. Salmon negotiate weirs that shad cannot, which means a river can look passable, hold salmon, and be closed to shad entirely above a modest structure.

THAT IS WHY A MAJOR RESTORATION PROGRAMME ON THE SEVERN was designed around shad specifically, fitting passes to a series of weirs. Shad were the design species precisely because they are among the least able of British migratory fish to negotiate an obstacle — solve the problem for shad and it is solved for everything else.

WHICH MAKES THE FISH A DIRECT MEASURE OF RIVER CONNECTIVITY. Where twaite shad are present above a structure, the river is genuinely passable. Where they have gone, the obstruction is the reason, and nothing else in a British river states the problem so plainly.

Twaite shad size matters chiefly because it is one of the things people use to separate the species from allis shad, and it is weaker evidence than it looks.

A TYPICAL ADULT ON THE SPAWNING RUN IS 30 TO 45 CENTIMETRES AND 0.5 TO 1.2 KILOGRAMS. Over 50 centimetres and 1.5 kilograms is a large fish, and reported maxima are around 60 centimetres.

ALLIS SHAD RUN LARGER — typically 40 to 55 centimetres with reported maxima approaching 80 — so a very large shad is more likely to be allis, and 'more likely' is as far as size will take anybody. The ranges overlap, individual fish vary, and hybrids occur. Size is supporting evidence and the gill raker count is the diagnostic.

THEY ARE MODERATELY LONG-LIVED FOR A CLUPEID, maturing at sea over several years before their first spawning run.

AND UNLIKE ALLIS SHAD THEY ARE MORE OFTEN ITEROPAROUS — a proportion of adults survive spawning and return in a later year. That single life-history difference has a direct practical consequence: an adult twaite shad returned alive may spawn again, which makes careful handling worth more here than for a species that dies after spawning regardless.

WHICH IS WORTH KNOWING BECAUSE SHAD SURVIVE HANDLING BADLY. The scales are deciduous and come away on contact, the fish are running to spawn, and they are protected. A shad unhooked in the water and never lifted is a fish that may come back; one laid on dry stones for a photograph very likely is not.

Twaite shad are a seasonal fish in the strongest sense: the entire freshwater fishery happens inside a few weeks.

THE RUN IS DRIVEN BY WATER TEMPERATURE rather than by date. Shad enter rivers in late spring as the water warms through a threshold, and the timing shifts between years and between rivers accordingly — a cold spring pushes the run later, a warm one brings it forward. Anybody planning around a calendar date rather than a thermometer will miss it in half of years.

SPAWNING HAPPENS AT NIGHT, over gravel in moderate flow, with pairs rolling audibly at the surface. It is one of the more conspicuous spawning events in a British river and it is the reason shad presence is documented as much by ear as by eye.

EGGS ARE SEMI-BUOYANT and settle into gravel interstices, which is the same requirement for clean gravel that runs through this whole group of fish.

POST-SPAWNING FISH DROP BACK DOWNSTREAM THROUGH EARLY SUMMER, and juveniles follow later in their first year.

FOR THE REST OF THE YEAR THEY ARE AT SEA OR IN ESTUARIES and are effectively unavailable, which is why a species that is locally abundant for three weeks is unknown to most anglers who fish the same river all season.

AND THE CONCENTRATION BELOW OBSTRUCTIONS IS BOTH THE OPPORTUNITY AND THE PROBLEM. Fish stopped by a weir gather in numbers that make for exceptional fishing and represent a population unable to complete its migration. Where fishing for them is permitted at all, it is permitted with that tension in mind — and what is permitted differs by river and by country, and is not stated here.

Twaite shad are among the poorest of all British fish at surviving being caught, and the reason is anatomical rather than behavioural. It is worth understanding, because the usual careful-handling instinct is not enough here.

THE SCALES ARE DECIDUOUS, WHICH MEANS THEY ARE DESIGNED TO COME OFF. A shad's scales attach loosely and detach at the lightest contact — a net, a hand, a stone, a dry sleeve. This is not fragility by accident; loosely attached scales are a predator-escape adaptation in clupeids, and a fish that leaves a mouthful of scales behind gets away.

WHAT THAT COSTS WHEN THE PREDATOR IS AN ANGLER is the barrier. Beneath the scales is skin and the mucus layer that keeps water out and infection away. A shad that has been held on a bank, in dry hands or in a coarse net has lost a patch of both, and the resulting osmotic and infection problem kills the fish days later where nobody sees it.

AND THE FISH IS ALREADY UNDER MAXIMUM STRESS. A shad in a river is on a spawning migration. It has stopped feeding, it is running on reserves, it is committed to a journey with a deadline, and it has nothing spare. A handling cost that a well-fed resident fish would absorb is a cost this fish cannot pay.

SO THE PRACTICE IS MORE ABSOLUTE THAN FOR ALMOST ANY OTHER SPECIES. Unhook in the water. Do not lift the fish out at all if it can be avoided. Never lay a shad on a bank, on grass, or on dry stones. If a net is used it should be soft, knotless and wet. Barbless hooks make in-water unhooking realistic rather than aspirational. And a photograph, if it is taken at all, is taken with the fish in the water.

THE LEGAL POSITION IS SEPARATE AND IT IS REAL. Shad are protected in Britain and across much of their range, what is permitted differs by river and by country, and closed areas and periods apply on the rivers where the main runs occur. Check the current position with the authority for that river before fishing for them — this is precisely the kind of rule that changes and that FishingHQ does not state.