Species & PresentationHook the Horizon · field intelligence

Reef & bottom · Saltwater

Gag grouper

Mycteroperca microlepis

Western Atlantic native, North Carolina to the Yucatan Peninsula (Mexico), with separately assessed and separately managed Gulf of Mexico (GMFMC) and South Atlantic (SAFMC) stocks.

Also called Gag.

  • Nearshore
  • Offshore
  • Regulated context
  • 4 of 4 overlays reviewed
  • Reviewed 2026-08-27
13 things this record does not know

Before you target this fish

Regulated context — check the rules for the exact water

Where this applies U.S. Gulf of Mexico (GMFMC) and South Atlantic (SAFMC) federal and adjoining state waters, North Carolina to the Yucatan Peninsula; Gulf and South Atlantic stocks are assessed and regulated separately.

The reviewed context, unedited

Both the Gulf and South Atlantic gag stocks were assessed as overfished in 2021 (not currently subject to overfishing per NOAA Fisheries), and both councils run seasonal closures plus size, bag, and trip limits that change from year to year - the South Atlantic runs a fixed January-April shallow-water-grouper spawning-season closure, while the Gulf recreational season in the current cycle has been closed for most of the year under separate stock-rebuilding rules. A federal descending-device requirement applies in South Atlantic federal waters for the whole snapper-grouper complex (standing rule since 2020); the equivalent Gulf reef-fish descending-device/venting-tool requirement lapsed in January 2026 and was, as of this review, in a proposed-renewal ('information gathering') phase rather than active regulation - verify its status before fishing Gulf federal waters. Verify current season status, size, and bag limits for the specific council/state before fishing.

Rules for this fish change at a state line and sometimes inside one. Check the ones that apply to the exact water you are standing on before you act on anything here — this record is biology, not permission.

Take this somewhere

This page is the record. The reading is what happens when you add water, a season and a temperature to it — that is where the families below get ranked against each other instead of just listed.

Start a readingRead Gag grouper on your waterOpens the analyst with this fish already picked.Forage & hatchHatch MatchWhat this fish is likely eating on that kind of water, at that time of year.TackleTackle Link AnalystWhether the line and terminal end you already own can deliver these families.WaterField Sense NavigatorWhere water like this exists, and what it is doing right now.

Those three links carry the fish and nothing else. No conditions were declared on this page, so none travel, and the link says so rather than sending an empty reading.

The half nobody publishes

What this record does not know

Everything else on this page comes from a named agency or peer-reviewed source. This is the other side of that: the questions a reviewer went looking for an answer to and came back without, and the fields the record leaves empty because filling them would mean guessing.

It is here rather than at the bottom because a page that only shows what it knows is easy to read as a page that knows everything. For Gag grouper there are 13 of them.

Named by a reviewer

9

Somebody looked for this and wrote down that they did not find it.

Behaviour

No thermally-driven behavior, current-facing behavior, cold-front response, or angling-pressure response was found in a usable source; all omitted rather than inferred.

Territoriality/aggression outside the spawning-aggregation context (which this record deliberately does not detail) was not clearly sourced.

Identification

Maximum size and longevity figures disagree between and even within NOAA Fisheries source material and NC DEQ; not resolved to a single number.

No additional regional common names beyond 'gag' were found in agency sources.

No thermal preference or tolerance data (°F) was found for this species in any agency or peer-reviewed source searched; omitted from the catalog record entirely rather than guessed.

Forage

No juvenile-specific or season-by-season diet breakdown was found in the sources reviewed.

No prey-size-shift or forage-substitution detail was found beyond the general adult prey list.

Season

This record deliberately omits any location, structure-naming, or timing detail about spawning aggregations beyond 'this is a management-closed period' - by design, not because the information doesn't exist.

Gulf recreational season status changes year to year and, in the current cycle, has been closed for the large majority of the year under separate stock-rebuilding rules rather than a simple fixed calendar window; this record describes the structure of that rule rather than committing to specific current-year open dates.

Absent from the record

4

No reviewer wrote a gap here. The field is simply empty, which is its own answer.

Water temperature

No agency or peer-reviewed temperature band for Gag grouper was found that a review would accept. The reading runs without one rather than borrowing a number from a related fish.

Spawning

No spawning account is recorded. For some species that is a missing source; for others it is deliberate, because the only available account describes an aggregation and naming one is exactly what gets a population fished out.

Identification

No reviewed image. A photograph is only in this catalog when an agency or a named creator labelled the subject, and nobody has cleared one for this species yet.

Population context

No regional population profile is registered. The species-level reading stands on its own; it does not silently become a local one.

Where the record puts it

Water and range

Western Atlantic continental shelf, North Carolina to the Yucatan Peninsula (Mexico); most abundant on the West Florida Shelf and off the Carolinas/Georgia. Management is split between the Gulf of Mexico and South Atlantic stocks; this record does not name specific reef, ledge, or wreck locations.

Nearshore

4 reviewed holding classes
  • Nearshore reef
  • Wreck
  • Rock pile
  • Artificial reef

Offshore

2 reviewed holding classes
  • Offshore ledge
  • Deep wreck

DepthAdults occupy hard-bottom, reef, ledge, and wreck habitat from roughly 60 to 500 ft. Juveniles use estuarine seagrass, oyster reef, and mangrove structure in much shallower water before moving offshore as they grow - a life-stage habitat this record does not target for fishing guidance.

Moving waterNo agency or peer-reviewed source found gave a tide- or current-specific preference for adult gag; they are described as hard-bottom/ledge residents rather than current-seam specialists.

LightNo agency or peer-reviewed source found made a specific claim about light response for this species; omitted rather than inferred from general grouper behavior.

Thermal band

Temperature

No reviewed temperature band

Nobody publishes a preferred or active temperature range for Gag grouper that a review would accept. Borrowing one from a related fish would look like knowledge and behave like a guess, so the reading runs without it and says which parts of the answer that weakens.

How it uses water

Behaviour

Life-stage habitat and social pattern differ sharply: nursery-stage fish are inshore and grouped near structure, while adult reef fish are more independent structure-holders.

Predatory grouper that ambushes from structure and pursues schooling baitfish and other reef fish; diet spans small forage fish, other reef fish, crustaceans, and squid.

No agency or peer-reviewed source made a specific day/night feeding claim for this species; recorded as mixed rather than assigned confidently.

CoverHard-bottom reef, wrecks, rocky ledges, and depressions offshore; seagrass, oyster reef, and shipwreck structure inshore during the juvenile/nursery stage.

Spawning (conservation context)Gag are protogynous hermaphrodites: individuals mature first as females, and some transition to male later (age at transition is not consistently reported across sources). They form spawning aggregations, which is the central conservation vulnerability of the species — an aggregation can be located and fished out faster than the stock recovers. Both councils close shallow-water grouper harvest for part of the year as a conservation measure; verify the current closure with the council or your state agency. Where and when those aggregations form is omitted from this record on purpose, and the closure exists to keep anglers away from that behaviour rather than to flag it.

Where the general rule stops

  • Gag are protogynous hermaphrodites that form spawning aggregations offshore in winter/early spring. This record never names, locates, or describes those aggregations as a structure class to fish, and spawning-season closures are recorded here purely as regulatory/conservation fact, not as a timing cue.

What it can eat

Forage

A capacity list, not a report from this week. What is actually available on your water is a separate question, and Hatch Match is the tool that asks it.
  • Small forage fish
  • Crustaceans
  • Mollusks
  • Larger prey fish

NOAA Fisheries lists round scad, sardines, porgies, snappers, grunts, crabs, shrimp, and squid as prey - a mix of small forage fish, other reef fish (larger_prey_fish class), crustaceans, and squid (mollusks class). Diet capacity is not evidence of a current feeding event.

Feeding style
Opportunistic
Feeding zone
Mixed

By life stage

Adult
Fish, crabs, shrimp, and squid, including other reef species such as porgies, snappers, and grunts; both adult gag and larger conspecifics are also reported to prey on juvenile gag.

Ontogenetic shiftJuveniles occupy estuarine nursery habitat before moving to offshore hard bottom as adults; specific juvenile diet composition was not found in the sources reviewed.

Diet capacity is not proof that a feeding event is happening now. Observed current forage still comes from a user observation or Hatch Match, never from this record alone.

Through the year

Season

Gag behavior in the sources reviewed is organized mainly around a juvenile-inshore-to-adult-offshore life history and around the winter/early-spring spawning-aggregation period, which is management-closed in both the Gulf and South Atlantic. Outside that closure, this record limits itself to structure classes already reviewed for nearshore and offshore hard bottom.

Winter

Where they sit
Offshore hard bottom, reefs, ledges, and wrecks.

What would count against it

  • targeting a spawning aggregation or treating aggregation structure as a class to fish
  • fishing without checking the current-year closure dates for the applicable council

Falls within the reported gag spawning-aggregation window (mid-January onward in the South Atlantic; late January onward in the Gulf). Both councils apply harvest closures covering some or all of this period. This is conservation/regulatory context only.

Early spring

Where they sit
Offshore hard bottom, reefs, ledges, and wrecks.

What would count against it

  • targeting a spawning aggregation or treating aggregation structure as a class to fish

Continued spawning-aggregation window and continued harvest closure in both regions through April in most cited closure structures.

Spring

Where they sit
Offshore hard bottom, reefs, ledges, and wrecks as the spawning-aggregation period ends.

What that changesOnce a jurisdiction's season is open, bottom contact and drop presentation over reviewed nearshore/offshore reef, ledge, and wreck classes apply.

What would count against it

  • assuming a season is open without checking the current-year council/state rule

South Atlantic spawning window is reported extending into early May; closures typically run through end of April.

Summer

Where they sit
Offshore and nearshore hard bottom, reefs, ledges, and wrecks; adults hold structure outside the spawning-aggregation period.

What that changesBottom contact, drop presentation, structure vertical, and deep drop over reviewed nearshore/offshore reef, ledge, and wreck classes, where the season is open.

What would count against it

  • fishing without a rigged descending device or venting tool where required
  • assuming a Gulf or South Atlantic season is open without checking the current-year rule

Fall

Where they sit
Offshore and nearshore hard bottom, reefs, ledges, and wrecks.

What that changesBottom contact, drop presentation, structure vertical, and deep drop over reviewed structure classes, where the season is open.

What would count against it

  • assuming season status carries over from the prior year without checking current rules

No spawning account is recorded. Sometimes that means no source was found. Sometimes it means the only available account describes an aggregation, and this catalog does not write those down.

Telling it apart

Identification

Adults: dark brownish-gray back and sides, pale belly, faint wavy dark markings. Juveniles/small adults: notably paler ground color with bold dark brown/charcoal blotches on the sides.

What to look at

  • Gill cover margin is deeply notched, distinguishing gag from the more smoothly rounded gill margin of black grouper (Mycteroperca bonaci).
  • Elevated dorsal and anal fin ray counts relative to many reef fish, per NOAA Fisheries' species description.
  • Larger adults are dark brownish-gray above with a paler underside and faint dark wavy markings on the sides.
  • Smaller individuals are markedly lighter overall with distinct dark brown or charcoal blotch ('kiss') markings on the flanks.
Average adult length
No single continent-wide average length figure was found; commonly landed legal fish cluster near the applicable minimum size (e.g. 24 in TL in the current Gulf recreational rule).
Common angling size
Legal recreational fish are commonly encountered near the minimum size limit in force for the council/state in question.
Typical weight
Not clearly sourced as a distinct 'typical' figure separate from the maximum-size figures below.
Maximum documented
Sources disagree: NOAA Fisheries states variously up to about 3 ft / 50 lb and, in a more detailed pull from the same species page, up to 58 in / 81 lb; NC Division of Marine Fisheries gives 51 in / 55 lb. Recorded as a range with the disagreement flagged rather than resolved to one number.
Longevity
Sources disagree: NOAA Fisheries states up to 30 years in one summary and 26 years in a more detailed pull from the same page; NC DEQ gives 15 years. Recorded as a range with the disagreement flagged.

What it gets confused with

Black grouper (Mycteroperca bonaci)
Gag has a deeply notched gill cover margin; black grouper's gill margin is more evenly rounded. Both are large, dark Mycteroperca groupers and are commonly confused.
Scamp
Scamp shows pronounced elongated soft dorsal and anal fin-ray extensions and a more concave head profile, plus a tan-to-grayish body with sharply defined, well-separated dark spots - a spotted pattern gag lacks.

What follows from all of that

Presentation families

These are the families the record will consider for this fish, and what each one has to do. They are not ranked here — ranking needs a season, a temperature and a piece of holding water, which is what the reading is for.

Nearshore

Bottom contact

Keep a bait on or just above the substrate along a break, flat, or inside a weed edge.

  • feel bottom
  • drag or hop
  • pause on the break
  • stay in contact
What it asks of the tackle
Depth control
High
Sensitivity
High
Casting distance
Moderate
Weight range
1/8–1/2 oz
Cover resistance
High
Line visibility
Low
Retie frequency
High

Drop presentation

Let a bait fall on a controlled line into cover, along a wall, or through a hole in vegetation.

  • place then fall
  • watch the line
  • hold at depth
  • short hop only after the fall
What it asks of the tackle
Depth control
High
Sensitivity
High
Casting distance
Short
Weight range
1/16–3/8 oz
Cover resistance
High
Line visibility
Low
Retie frequency
High

Structure vertical

Hold a presentation in the water column directly over hard structure and stay there as the boat moves.

  • stay vertical
  • hold the depth band
  • short lifts
  • reset when the line angles
What it asks of the tackle
Depth control
High
Sensitivity
High
Casting distance
None
Weight range
2–16 oz
Cover resistance
High
Line visibility
Secondary
Retie frequency
High

Vertical jig

Work a compact bait up and down through a marked depth, basin, or timber pocket.

  • stay over the target
  • measured lift
  • controlled drop
  • watch slack
What it asks of the tackle
Depth control
High
Sensitivity
High
Casting distance
Vertical
Weight range
1/8–3/4 oz
Cover resistance
Moderate
Line visibility
Low
Retie frequency
Moderate

Live / natural bait suspension

Present a natural food form with enough life or scent to hold in a station without looking mechanical.

  • keep it alive or fresh
  • match the holding depth
  • minimize hardware bulk
  • detect without pulling it away
What it asks of the tackle
Depth control
High
Sensitivity
High
Casting distance
Short to moderate
Weight range
As light as conditions allow
Cover resistance
Moderate
Line visibility
Low
Retie frequency
High

Offshore

Vertical jig

Work a compact bait up and down through a marked depth, basin, or timber pocket.

  • stay over the target
  • measured lift
  • controlled drop
  • watch slack
What it asks of the tackle
Depth control
High
Sensitivity
High
Casting distance
Vertical
Weight range
1/8–3/4 oz
Cover resistance
Moderate
Line visibility
Low
Retie frequency
Moderate

Deep drop

Put bait on the bottom in water deep enough that the drop itself is most of the work.

  • heavy enough to go straight down
  • know when you are down
  • short lift to check
  • wind steadily
What it asks of the tackle
Depth control
High
Sensitivity
Low
Casting distance
None
Weight range
8–48 oz
Cover resistance
Moderate
Line visibility
Secondary
Retie frequency
Moderate

Suspended stationary

Park a live or scent bait in the column where fish are already using a depth band.

  • find the band
  • hold it
  • minimal motion
  • refresh bait
What it asks of the tackle
Depth control
High
Sensitivity
Moderate
Casting distance
Short to vertical
Weight range
Sinker as needed
Cover resistance
Low
Line visibility
Low
Retie frequency
Moderate

Live-bait slow troll

Move live bait just fast enough to cover water while it still swims naturally.

  • barely-moving speed
  • bait leads the boat
  • let it swim
  • drop back on a follow
What it asks of the tackle
Depth control
Moderate
Sensitivity
High
Casting distance
None
Weight range
Unweighted to 4 oz
Cover resistance
Low
Line visibility
Low
Retie frequency
Moderate

Chum-established drift

Establish a scent trail and drift baits back through it at the speed the current is already moving.

  • consistent trail
  • unweighted or lightly weighted drop-back
  • match the sink to the drift
  • do not outpace the trail
What it asks of the tackle
Depth control
Low
Sensitivity
High
Casting distance
None
Weight range
Unweighted to 2 oz
Cover resistance
Low
Line visibility
Low
Retie frequency
Moderate

What moves them for this fish

Reviewed rules that push particular families up when the conditions match. Each one names the conditions it needs and why it exists, so you can disagree with it.

  • Gag are described as ambushing from structure and actively pursuing schooling baitfish and other reef fish, not just picking the bottom, so when fish forage is actually present a worked or held presentation in the column outranks a bottom search.

    When

    Nearshore · Small forage fish, Larger prey fish

    Moves up

    Vertical jig, Live / natural bait suspension, Bottom contact

    Reviewed 2026-08-30

  • The same documented pursuit behavior favors a naturally swimming or actively worked presentation over a bait parked on bottom when fish forage is verified offshore.

    When

    Offshore · Small forage fish, Larger prey fish

    Moves up

    Live-bait slow troll, Vertical jig, Chum-established drift, Deep drop

    Reviewed 2026-08-30

Where every sentence came from

Sources

Reviewed 2026-08-27, next review 2026-11-27. Each entry says which part of the page leans on it, so you can check the claim you care about rather than the whole list.

  1. Agency

    NOAA Fisheries - Gag Grouper species page

    Used for habitat, thermal band and presentation families; identification; behaviour; forage; season. Read 2026-08-30, next check 2026-11-27.

  2. Agency

    SAFMC - Grouper, Gag species page

    Used for habitat, thermal band and presentation families; identification; behaviour; season. Read 2026-08-30, next check 2026-11-27.

  3. Agency

    Gulf of Mexico Fishery Management Council - Grouper, Gag species page

    Used for habitat, thermal band and presentation families; behaviour; season. Read 2026-08-30, next check 2026-11-27.

  4. Agency

    NC Division of Marine Fisheries - Gag Grouper species profile

    Used for habitat, thermal band and presentation families; identification; behaviour. Read 2026-08-30, next check 2026-11-27.

A source with no link predates the rule that one has to carry a URL. It is still a real citation and still checkable; it just takes a search rather than a click, and that is worth knowing before you rely on it.