Blue Shark
Blue sharks arrive in Irish offshore waters each summer, following warm surface currents and the mackerel shoals that push in from the Atlantic.
A small but committed charter fleet runs dedicated trips well offshore to target them — primarily on a catch, tag, photograph, and release basis.
Ireland has been central to one of the world's longest-running shark tagging programmes since 1970, and the Celtic Sea shelf off the south coast is now recognised as an Important Shark and Ray Area for the species.
Scientific Name: Prionace glauca
Also known as Blue, Great Blue Shark
- Slender, streamlined build with a long pointed snout and notably large eyes — unmistakable among Irish sharks once you've seen one.
- Colouring is distinctive: dark indigo-blue back fading to bright electric-cobalt sides, then a clean white belly.
- Very long pectoral fins and a long, sickle-shaped tail with a deep notch on the upper inner edge; dorsal fin is relatively small.
- Most fish encountered off Ireland are females up to around 220cm; the Irish record stands at 206lb, with the specimen threshold at 100lb.
What to know
Habitat Distribution
- A long-distance oceanic migrant — not resident in Irish waters year-round, but present from roughly June to October along the south, west, and north coasts.
- Moves through pelagic (open-water) and offshore environments, typically hunting in the upper water column but found at depths of 150–250 feet over the continental shelf.
- The Celtic Sea shelf off the south coast is a recognised concentration area, particularly for smaller female sharks; the west coast from Cork to Galway and north to Donegal also holds fish seasonally.
- Aggregations tend to be size- and sex-segregated — the fish encountered by Irish charter boats are predominantly young females.
Key Locations
- Cobh and Cork Harbour — the top venue by ISFC specimen submissions, with charters running from Crosshaven, Kinsale, and Courtmacsherry into the Celtic Sea.
- West Cork (Courtmacsherry) — a long-established shark charter base with direct access to productive offshore grounds.
- Galway and Clare coast — charters depart from Rossaveal and Spiddal into the Atlantic, with reliable late-summer shark fishing.
- North and West Donegal — Downings, Port-na-blagh, beyond Lough Swilly, and the Killybegs area all have records of good fish.
- Ram Head, Ardmore (County Waterford) — used as a base for tagging research trips into the Celtic Sea.
Specific Spots
- Work well offshore over the continental shelf edge — blue sharks follow the thermocline and baitfish concentrations rather than fixed bottom structure.
- A rubby-dubby slick (a mix of mashed oily fish like mackerel, deployed over the stern) is the standard method for drawing sharks up to the boat in open water.
- Fish are typically found in the upper water column; baits fished at varying depths under a float cover the zone where sharks are actively feeding.
- Proximity to mackerel shoals is the single biggest locating factor — where the bait is, the blues follow.
Blue Shark FAQ
Answers from onWater's species guide.
What are the best lures and bait for Blue Shark?
Fresh whole mackerel or large mackerel fillets are the go-to bait on Irish shark charters, oily, visible in a slick, and exactly what the sharks are already eating. Squid, either alone or combined with mackerel, works well and holds on the hook reliably in a current.
What flies work for Blue Shark?
Large saltwater streamers, Clouser Minnows (which imitate baitfish) and Deceiver-style patterns in white, blue, or mackerel colours, are the flies most likely to draw a strike when cast into an active rubby-dubby slick.
When is the best time to fish for Blue Shark?
June to October, the window when blue sharks are reliably present in Irish offshore waters, tracking warm surface currents and mackerel shoals. August and September, the peak months by ISFC specimen records, when fish are most consistently encountered on charter trips.
How do you catch Blue Shark?
Blue shark fishing in Ireland is almost exclusively a charter-boat pursuit, running well offshore over the continental shelf. Skippers deploy a rubby-dubby slick of mashed mackerel to draw sharks to the boat, then fish whole or fillet mackerel baits under balloon floats at varying depths.
What do Blue Shark eat?
Mackerel and other baitfish make up a large part of the diet in Irish waters, whole or fillet mackerel on a wire trace is the standard boat bait, and it works because it directly matches what the sharks are already hunting.
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