Atlantic Horse Mackerel
Scad — as most Irish anglers call them — are a shoaling pelagic fish that show up around Ireland's west and northwest coasts from midsummer into autumn.
They're not the primary target of most boat trips, but a feathers rig dropped into a moving school can produce multiple fish at once, and they're genuinely useful as fresh bait. Donegal and Clare are the standout counties, with Galway Bay a reliable producer.
Scientific Name: Trachurus trachurus
Also known as Scad, Bolmán
- Slender, compressed body with a distinctive row of large bony scutes (hard, keeled scales) running the full length of the lateral line — unmistakable in hand.
- Blue-green to grey-green back, silvery-white belly; a clear black spot on the gill cover helps separate scad from true mackerel at a glance.
- Two separate dorsal fins; the first is tall and spiny, the second long and low — similar layout to mackerel but the scutes are the giveaway.
- Most Irish fish run under 500g; anything over 500g (about 1 lb) is considered a good specimen here.
What to know
Habitat Distribution
- Native to the northeast Atlantic; present in Irish waters as part of the western stock that spawns off the coasts of western Europe.
- Pelagic and schooling — they roam the water column from the surface down to depth, typically found in coastal and shelf-edge waters rather than tight inshore structure.
- Most consistently encountered off the west and northwest coasts: Donegal Bay, Galway Bay, and the Clare coast are the reliable areas for sport anglers.
- Occasional catches from shore, but the bulk of angling encounters happen from boats working open water over sandy or mixed ground.
Key Locations
- Donegal Bay — one of the most consistently productive areas for scad in Ireland, with marks around Portsalon among the noted spots.
- Galway Bay and the Clare coast — reliable summer and autumn grounds, with Carrigaholt a named mark for the species.
Specific Spots
- Open water above sandy ground where baitfish schools concentrate — scad follow the food, so watch for surface activity or birds working the water.
- Tide races and headland eddies funnel plankton and small fish, pulling scad schools into predictable holding areas.
- Mid-water to surface in summer; as light increases midday the schools tend to drop deeper, so early morning and evening sessions over known marks produce best.
Atlantic Horse Mackerel FAQ
Answers from onWater's species guide.
What are the best lures and bait for Atlantic Horse Mackerel?
Multi-hook feather or sabiki rigs with small (size 4–8) shiny hooks are the standard approach, drop to the school, jig gently, and multiple fish at once is the norm. Small metal slices (10–20g) and slim spinners retrieved at pace work when fish are feeding near the surface and you want a more active approach.
When is the best time to fish for Atlantic Horse Mackerel?
July to October is the main window, with August the peak month based on Irish catch records. Good numbers are present through July, September, and into October before fish move offshore for winter.
How do you catch Atlantic Horse Mackerel?
Scad are almost always targeted from a boat rather than shore in Ireland, using multi-hook feather or sabiki rigs worked through the water column once a school is located.
What do Atlantic Horse Mackerel eat?
Small crustaceans, squid, and smaller fish, they filter and chase prey through the water column in a school, which is why a string of small shiny feathers or sabiki-style rigs (multiple small hooks dressed with flash material imitating tiny fish or shrimp) works so well.
Where do Atlantic Horse Mackerel live?
Native to the northeast Atlantic; present in Irish waters as part of the western stock that spawns off the coasts of western Europe. Pelagic and schooling, they roam the water column from the surface down to depth, typically found in coastal and shelf-edge waters rather than tight inshore structure.
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