European lobster

A lobster is measured by CARAPACE LENGTH: from the rear of the eye socket to the back edge of the carapace, excluding the entire tail. That is counter-intuitive — the tail is most of what people see and most of what they eat — and it is what every minimum landing size is written in. A total-length figure is not a legal measurement anywhere.

ANIMALS AROUND THE USUAL MINIMUM run nine to thirteen centimetres of carapace. That corresponds to a lobster most people would call medium and would be pleased with.

A GOOD ONE is over fifteen centimetres of carapace.

THE EXCEPTIONAL END reaches carapace lengths above twenty centimetres and weights over five kilograms. Much larger historical figures circulate and are poorly evidenced, which is the same problem this catalogue records for maximum fish sizes and for the same reason: the biggest claims are the least checked.

AND THE AGE IS THE POINT. Lobsters are slow-growing and long-lived, with individuals surviving several decades and possibly longer, and growth happens only at moulting with the interval lengthening throughout life. A large lobster has been on that piece of ground for a very long time. Combined with strong site fidelity — an animal holds territory and does not travel far — this means a stretch of coast fished hard does not restock itself from elsewhere in any useful period.

THE MINIMUM SIZE IS SET CLOSE TO THE SIZE AT MATURITY in many areas, which is precisely why it is where it is: the intention is that an animal breeds at least once before it can be taken. That also means the margin is thin, and an animal a few millimetres under is not a near miss but a lobster that has not yet spawned.

SOME FISHERIES ALSO APPLY A MAXIMUM SIZE, protecting the large, highly fecund females for the same reason slot limits protect large fish. Where that applies, the biggest animal you catch is the one you must return.

CARRY A GAUGE. Carapace length cannot be judged by eye and the measurement start point — the eye socket, not the tip of the rostrum — is easy to get wrong by enough to matter.

A lobster is the strongest animal most people will ever pick up with their hands, and the two ends do quite different things.

THE CLAWS ARE THE INJURY. The crusher is capable of a serious crushing injury to a finger, it closes fast, and the animal will use it on whatever is gripping it. Hold across the back of the carapace, BEHIND the claws, where neither can reach.

THE TAIL IS THE ESCAPE. A lobster's abdominal flick is powerful enough to drive it out of an unprepared hand, and it is the movement that gets an animal dropped onto rock or a deck. Support the tail with the other hand. Do not lift by an antenna, which breaks, or by a claw, which is shed.

BANDING is standard on animals being kept, and the reason is not primarily human safety: lobsters are aggressive toward each other and two unbanded animals in a box will maim each other.

KEEPING ONE ALIVE. Cool, damp and shaded. Not in fresh water and not in still tap water, both of which kill quickly. Not in a sealed container. A lobster kept properly survives a long journey and one kept badly does not survive an afternoon.

THE ANIMALS THAT GO BACK IMMEDIATELY, and this list is not discretionary. Anything under the minimum carapace length. Any berried female — eggs cemented beneath the abdomen, unmistakable once seen. And any V-NOTCHED animal.

THE V-NOTCH IS WORTH EXPLAINING because almost no angler has heard of it. In many lobster fisheries, a berried female found in a pot has a small wedge cut from one of the fan-shaped tail flippers before she is returned. The notch persists through several moults, and while it remains visible that animal may not be landed by anybody, in any season, at any size. It is a protection that travels with the individual rather than with the calendar, it is run largely by fishers themselves, and it is one of the more elegant measures in fisheries management. If you land a notched lobster, it goes back — and finding one means the system is working.

RETURNING ANIMALS should be done to the bottom where possible rather than dropped from height, and gently: a lobster landing badly on rock is injured.

AND FOR THE TABLE, the welfare position has changed materially. Several jurisdictions now recognise decapod crustaceans as sentient in law, and current guidance favours chilling to reduce responsiveness followed by rapid mechanical dispatch over immersion of a live animal in boiling water. Establish the current position rather than repeating older practice.

Lobster seasonality is a question about behaviour rather than about distribution, because unlike almost every other species in this catalogue the animal does not go anywhere.

LOBSTERS HOLD TERRITORY. An individual occupies a hole or crevice in hard ground, forages from it at night, and returns to it — and does so over long periods, in the same place. There is no seasonal migration to describe. So when a pot fishery becomes productive in warmer water and unproductive in cold, the lobsters have not arrived or departed; they have become more or less willing to leave the hole and walk to a bait.

THAT IS A METABOLIC STORY. Lobsters are ectothermic, and in cold water their activity, feeding rate and movement fall away substantially. A baited pot works by scent reaching an animal that then walks to it, and both halves of that — the plume dispersing and the animal being inclined to follow it — weaken in cold water. Pot fisheries in the cooler parts of the range are correspondingly seasonal, and the seasonality is one of catchability rather than of abundance.

THE MOULT CYCLE OVERLAYS IT exactly as it does for crab. Lobsters moult chiefly in the warmer months, splitting and discarding the entire exoskeleton and extracting themselves from it, and a freshly moulted animal is soft, hiding, defenceless and poor eating. Those animals are not in pots because they are not out foraging, which is fortunate; the ones taken shortly after hardening are, and they carry little meat for their size.

BERRIED FEMALES are females carrying eggs attached beneath the tail, and they carry them for the better part of a year before the larvae hatch. Returning them is standard practice throughout the fishery and is a legal requirement in most of it, and V-notching schemes — cutting a mark into the tail fan of a breeding female before release, which persists through several moults — exist specifically to protect that part of the population beyond a single season.

What is legally required, permitted or prohibited in any place is current, local, frequently strict, and not stated by this record.

Lobster reproduction takes place on a timescale that makes the protection of breeding females unusually consequential, and the mechanics are worth understanding because they explain why the rules are shaped as they are.

MATING HAPPENS AT THE MOST VULNERABLE MOMENT. A female can only mate immediately after moulting, while her new shell is still soft. She seeks out a male's shelter beforehand, moults there, mates, and remains while the shell hardens — the male's territory functioning as protection during the period she is defenceless. Reproduction and the moult cycle are therefore locked together, which means a female's reproductive schedule is constrained by her growth schedule.

SHE THEN CARRIES THE EGGS FOR THE BEST PART OF A YEAR. Fertilised eggs are cemented to swimmerets beneath the abdomen, where she holds, aerates and cleans them through many months before releasing planktonic larvae. During that time she is described as BERRIED, and she is carrying her entire reproductive investment externally, visibly, on her body.

WHICH IS WHY BERRIED FEMALES ARE PROTECTED ACROSS ESSENTIALLY THE WHOLE RANGE. Taking one removes not a lobster but a lobster and a year's brood, at a point where the investment is nearly complete. Returning a berried animal is not discretionary and is not a courtesy.

AND V-NOTCHING EXTENDS THAT PROTECTION BEYOND THE SEASON. A wedge cut from a tail flipper of a berried female before release marks her as permanently unlandable while the notch remains visible — and because the mark persists through several moults, it protects her for years rather than for the one season in which she happened to be carrying eggs. It is an elegant piece of design: it converts a temporary, visible condition into a durable one, and it targets protection at proven breeders specifically.

THE LARVAL STAGE IS THE WEAK LINK. Released larvae are planktonic for a period, drifting and moulting through several stages before settling to the bottom, and survival through it is very low. That is why the number of eggs a female carries is large and why the loss of a berried female is disproportionate — the fraction that make it is small enough that the number starting matters.

Lobster habitat is unusually easy to state and unusually consequential, because a lobster is an animal that lives in a specific hole and the availability of holes sets how many lobsters a piece of ground can hold.

THE REQUIREMENT IS HARD, BROKEN, SHELTERED GROUND. European lobsters occupy rocky reef, boulder fields, bedrock with crevices, cobble, and the artificial equivalents — harbour walls, breakwaters, wreckage, pipeline and rock armour. What matters is not the rock itself but the spaces in it: a lobster needs a burrow or crevice it can back into and defend, sized to the animal. Featureless bedrock holds few lobsters; a jumble of boulders on a sand interface holds many.

WHICH MAKES SHELTER THE LIMITING RESOURCE RATHER THAN FOOD. Lobsters are territorial and aggressive toward each other, and a good hole is contested. That is why lobster density tracks structural complexity so closely, and why artificial structure — the base of a breakwater, a wreck, deliberately placed reef — recruits lobsters reliably. It is also why a lobster's home range is small: it is centred on a shelter and the animal returns to it.

THE DEPTH RANGE IS SHALLOW BY MARINE STANDARDS. European lobsters occur from the low intertidal down onto the shallow shelf, with most of the recreationally and commercially exploited population in relatively shallow inshore water on rough ground. That shallowness is why the fishery is a pot fishery worked from small boats and why the ground is a coastal rather than an offshore resource.

BEHAVIOUR SPLITS DAY FROM NIGHT AND IT MATTERS. Lobsters shelter through the day and emerge at night to forage over the surrounding ground for molluscs, crustaceans, worms and carrion. So the habitat is really two: the shelter, which is hard structure, and the foraging ground, which is often the softer sediment beside it. The interface between the two is where lobsters concentrate.

AND JUVENILE HABITAT IS DIFFERENT AND MORE FRAGILE. Newly settled lobsters need small interstitial spaces — cobble and gravel with gaps a few centimetres across — and they are cryptic and sedentary for their first years. Ground that supports adults does not necessarily support settlement, which is why nursery habitat is a separate conservation subject from adult ground, and why damage to shallow cobble can affect a fishery years later.

Lobster reproductive behaviour is the reason for the most distinctive management measure in British and European inshore shellfishing, and understanding one explains the other.

MATING REQUIRES THE FEMALE TO BE SOFT, WHICH MAKES IT DANGEROUS FOR HER. A female lobster can only mate immediately after moulting, when her new shell is still soft. She is defenceless in that window, and the behaviour reflects it: the male guards her in his shelter before the moult, mates, and continues to guard her afterwards until the shell hardens. That is a genuine pair association in an otherwise aggressive and solitary animal, and it lasts days.

SHE THEN STORES THE SPERM AND USES IT ON HER OWN SCHEDULE. Fertilisation happens later, sometimes considerably later, when she extrudes the eggs and cements them to the swimmerets under her tail. That decoupling means mating and egg-bearing are separate events that need not be in the same season.

THE BERRIED STAGE LASTS THE BEST PART OF A YEAR AND SHE IS BARELY MOBILE THROUGH IT. A berried female carries the whole clutch externally, shelters, feeds little, and cannot moult. Every egg is exposed to whatever happens to her, and she has invested a year of her growth in them.

WHICH IS WHY BERRIED FEMALES ARE PROTECTED ESSENTIALLY EVERYWHERE, and why the protection is not treated as discretionary. Taking one removes a whole brood at the point of maximum investment, from the animal least able to avoid a pot.

AND V-NOTCHING IS THE MEASURE BUILT ON TOP OF THAT. In many fisheries a berried female found in a pot has a wedge cut from a tail flipper before release. The notch marks her as unlandable for as long as it remains visible — which is across several moults — so the protection follows the animal rather than the season. A notched lobster returned is not a favour; in the jurisdictions that operate the scheme it is a requirement, and landing one is an offence.

THE LARVAE GO INTO THE PLANKTON and drift through several stages before settling into cobble and gravel as tiny lobsters, which is why juvenile nursery ground is a separate conservation subject from the adult reef the fishery works.

WHAT THE RULES ARE IN ANY PARTICULAR PLACE — minimum size, notching, berried protection, licensing, pot limits — is a matter for the competent authority, and they differ between adjacent districts.