Black musselcracker

The poenskop's life history is the argument for South African linefish management in a single species, and it is worth setting out in the order the numbers happen.

A FEMALE MATURES AT ABOUT 53 CM FORK LENGTH AND TEN YEARS OLD. THE LEGAL MINIMUM SIZE IS SHORTER THAN THAT. A fish that is legal to keep has therefore, in the general case, never bred — and that is a fact about the relationship between the rule and the biology rather than a figure, which is why it stays true when the figure changes.

AT ABOUT 70 CM FORK LENGTH AND EIGHTEEN YEARS THE FISH CHANGES SEX, female to male.

EVERY FISH OVER 95 CM FORK LENGTH IS A MALE. There are no large females.

SO THE TROPHY FISH ARE THE BREEDING MALES, and a fishery that concentrates on the biggest fish — which every fishery does, because that is what people want to catch and photograph — is removing them selectively. In a protogynous species that does not simply reduce numbers; it can leave a population of females with nothing to spawn with, and the recovery time is measured against a forty-five-year maximum age.

WHICH IS WHY THE INSTITUTE'S OWN NOTE ON MARINE PROTECTED AREAS IS EMPHATIC. The residency of both juveniles and adults means well-enforced no-take reserves with suitable reef are described as extremely important for this species throughout its range. A fish that does not move is a fish a boundary protects — and a fish an accessible ledge can be emptied of.

THE PRACTICAL READING for somebody who catches one is short. This is one of the slowest-growing fish in southern African water, the legal minimum is below maturity, and the daily bag limit is a maximum rather than a plan.

SOUTH AFRICA REGULATES SEA FISHING SPECIES BY SPECIES, WHICH IS NOT HOW MOST COUNTRIES DO IT.

A recreational permit is the entry ticket and not the whole of it. On top of it sits a minimum size and a daily bag limit SET PER FISH, a closed season on a small number of species, and a cumulative daily cap across everything caught — so being inside the limit for each species separately does not put you inside the limit overall.

THERE IS A CAP ON HOOKS on a rod-and-line permit. A spearfishing permit is separate, allows no breathing apparatus beyond a snorkel, and PROHIBITS SPEARFISHING IN AN ESTUARY — a flat ban rather than a limit, and the rule visitors most often do not know.

A LANDED FISH MUST KEEP ITS HEAD AND TAIL so its length can be checked. Nothing caught on a recreational permit may be sold by anyone. And a small list of species may not be caught, landed or possessed at all.

FISHINGHQ DOES NOT PRINT THE FIGURES, and the reason is on this page rather than in a policy document: the department's own guidance says adjustments may be forthcoming given the acknowledged crisis of linefish, the numbers differ by species and by area and by whether you were standing on a beach or sitting in a boat, and a stale figure on a fishing site is worse than no figure at all. Get the current position from the Department of Forestry, Fisheries and the Environment, and get the protected-area position from whichever body manages the stretch of coast you are on.

Extraordinarily slow. Females mature at about 53 cm fork length and around ten years of age. Sex change from female to male occurs at about 70 cm fork length and roughly eighteen years, and all fish greater than 95 cm fork length are male. Maximum recorded age is forty-five years. A legal-sized fish at 50 cm total length is therefore a fish that has not yet bred, and the largest fish in any population are its breeding males.

A protogynous hermaphrodite: individuals function first as females and change to male at about 70 cm fork length. Spawning takes place from May to October in Transkei and KwaZulu-Natal waters, and some adults undertake a one-way movement up the east coast, presumably to spawn — which means the fish contributing to reproduction may not be the fish in front of the angler who catches them.

Crushes molluscs, crustaceans and echinoderms with powerful conical teeth. Particularly partial, on the research institute's own capture note, to rock lobster tails and small reef fish. It is a bottom-oriented reef feeder that works structure rather than open ground, which is why it is caught against the base of a reef and why a hooked one is in the reef before the angler has finished reacting.

Scent and close-range vision over high-profile reef. Like the other large crushing sparids it is a fish that finds food rather than chases it, and it is caught on static natural bait rather than on anything worked.

Juveniles are highly resident in the Eastern and Western Cape and stay put. Some adults undertake a unidirectional movement up the east coast to Transkei and KwaZulu-Natal water, presumably to spawn, between May and October. That mix — resident juveniles, migrating adults — is why the institute records no-take marine protected areas with suitable reef habitat as extremely important for the species throughout its range.

The great prize of South African rock-and-surf angling and a heavily targeted spearfishing species, caught by shore anglers, spearfishers and ski-boat crews throughout its range. It is on the department's CRITICAL list at a strict daily bag limit with a minimum size, it is IUCN Vulnerable, it is SASSI red, and it is estimated at about twenty per cent of historical abundance. Almost everything an angler catches is an immature fish.

TREAT THIS ONE AS A RELEASE UNLESS IT IS A CONSIDERED DECISION. A fish at the fifty-centimetre minimum has not bred; a fish worth photographing is likely a breeding male the population cannot spare.

SUPPORT THE BODY HORIZONTALLY. It is a deep, heavy fish and hanging one by the jaw for a photograph loads several kilograms onto a joint that is not built for it.

THE TEETH ARE FOR CRUSHING SHELL and a hand in the mouth comes out marked. Use a de-hooker.

BAROTRAUMA IS A REAL CONSIDERATION FROM A BOAT. Fish brought up from reef at forty metres or more may need venting or a descending device to return successfully; a fish that floats away on the surface is a dead fish however carefully it was unhooked.

AND IT GOES BACK WHERE IT CAME FROM. A resident reef fish returned in the wrong gully is a fish with a problem.