Clanwilliam yellowfish

Most of the fish in this programme are in trouble because of fishing. This one is not, and the difference is worth understanding.

THE CLANWILLIAM YELLOWFISH IS ENDANGERED because of INTRODUCED PREDATORY FISH above all. Smallmouth bass and trout were stocked into Cape rivers through the twentieth century for angling, and they occupy exactly the shallow marginal and tributary water that juvenile yellowfish need. The adults are not eaten. The young are, and a river can hold adult yellowfish for decades while producing almost no recruits.

THE SECOND CAUSE IS FLOW. Abstraction for agriculture, damming and flow regulation remove both the seasonal cue that triggers the spawning migration and the condition of the gravel the fish spawn on. A river that no longer floods in spring is a river where a year class fails silently.

AND ANGLING IS NOT ON THE LIST in any serious way, because the fishery is small, permitted and released.

WHICH MAKES THE RECOVERY WORK UNUSUAL AND HOPEFUL. The intervention that works for the Cape's endemic fishes is REMOVING alien fish from headwater tributaries — a barrier, a clearance, and a reach that belongs to the native species again. It has been done in the Cape Fold ecoregion with measurable results, and the Olifants system is among the places it has been attempted.

THE POINT THAT GENERALISES. 'Is this species threatened by fishing?' is a question worth asking separately from 'is this species threatened?', and answering the second by assuming the first is how conservation effort gets pointed at the wrong thing. For a galjoen the answer is fishing. For this fish it is a bass somebody released in 1940.

A slow-growing, long-lived river cyprinid that matures late and depends on seasonal flow to spawn. Juveniles use shallow marginal and tributary habitat, which is exactly the habitat introduced smallmouth bass occupy — and that overlap, rather than any adult mortality, is the mechanism behind the decline.

Spawns in spring and early summer on gravel and cobble in flowing water, moving upstream into tributaries to do it. The species depends on a natural flow regime: abstraction, damming and flow regulation remove both the migration cue and the substrate condition, and a river that no longer floods properly is a river where a year class fails without anybody catching anything.

An omnivore taking aquatic invertebrates, algae and detritus from rock and gravel in flowing water, with larger fish taking more substantial prey including small fish. For an angler that means nymphs, small streamers and terrestrial patterns fished to sighted fish in clear water, which is the character of the fishery.

Vision in clear mountain water, supported by the barbels for feeling over substrate. A sighted yellowfish in low clear summer flow can see the angler, which is what makes it a stalking fishery rather than a covering-water one.

The fishing season is the low clear summer flows, when fish can be sighted in the pools and runs of the Doring and the upper Olifants. Spawning migration into tributaries happens in spring and early summer on rising flows, and the fish are correspondingly harder to find and better left alone at that time.

One of the finest freshwater fly-fishing propositions in Africa: sight fishing to a large, powerful, golden cyprinid in clear mountain water. The fishery on the Doring is well known among South African fly anglers and operates through permits and landowner access rather than through a national bag limit. It is an Endangered species and the fishery is a catch-and-release one in practice.

AN ENDANGERED FISH IN WARM SHALLOW SUMMER WATER, which is the hardest combination there is for a release.

BARBLESS HOOKS AND A KNOTLESS RUBBER NET. Nothing else is appropriate on this fishery.

KEEP IT IN THE WATER. Unhook in the net in the river. If a photograph is being taken, have the camera ready first and lift the fish for no more than a few seconds.

WET HANDS ALWAYS. Dry hands and hot rock both strip the mucus coat, and a fish held against a dry shirt for a photograph is being injured.

DO NOT FISH FOR THEM IN VERY WARM LOW WATER. A fish played to exhaustion in warm water frequently does not recover, and a hot afternoon on a low river is the time to stop.

AND CHECK THE PERMIT AND ACCESS POSITION. This is a permitted, landowner-mediated fishery rather than open water.