Blue Mackerel fish identification, its habitats, characteristics, fishing methods.
Blue Mackerel are a schooling pelagic fish, one of the smallest species of the Scombridae family (tunas and mackerels) and capable of extensive migrations. Widely spread in temperate waters of the Pacific Ocean around the North Island and northern South Island. They are often found with schools of Jack Mackerel and Kahawai, where they swim under these species in surface waters down to 200 m (660 ft). Its length is between 30 and 65 cm (12 and 25 in), and weight over a kilogram (2 lbs). Blue mackerel are an oily fish with a high fat content. The flesh is dark but lightens when cooked. The high oil content makes it is an excellent fish for smoking.
The Blue mackerel, Scomber australasicus, also known as Japanese mackerel, Pacific mackerel, Southern mackerel, Slimy mackerel, Spotted chub mackerel, Goma saba (Sesame mackerel) in Japan, Maquereau austral in France, Maccerello in Italy, Caballa in Spain, Skumbriya in Russia, is a fish of the family Scombridae, found in tropical and subtropical waters of the Pacific Ocean from Japan south to Australia and New Zealand from North West Cape to Moreton Bay, including Tasmania and Lord Howe Island, in Eastern Pacific in Hawaii and Mexico, Socorro Island, in the Indo-West Pacific in Red Sea, Persian Gulf, Gulf of Oman and the Gulf of Aden.
The Blue Mackerel has a fusiform spindle-shaped body; tuna shape (a rounded body tapering from second dorsal fin to the tail). The height of the body is 5 and a half times in the total length. The head is small, the length of the head 4 and 1/4th, with large eyes, and the fins fold back into grooves creating a streamlined appearance and pointed snout. 2 widely separated dorsal fins, 5-6 finlets behind dorsal and anal fins, and 2 small keels at the base of each caudal-fin (tail) lobe. The eyes have adipose eyelids that leave a vertical slit over the pupils. There is a single row of sharp pointed very distinct teeth in each jaw. The body is covered in small scales.
Distinguishing characteristics: Palatine narrow. Anal fin origin is clearly more posterior than second dorsal fin. Anal fin spine independent from anal fin. Swim bladder is present. Snout pointed. Interpelvic process is small and single. Color is back with narrow oblique lines which zigzag and undulate; the belly is pearly white and marked with thin, wavy broken lines.
10-13 Dorsal spines
11-12+5-6 Dorsal soft fin rays
10-12+5-6 Anal soft rays
20-21 Pelvic fin rays
17 Caudal fin rays
Max. length: 65cm. Common 10-14 in
Common weight 3-4 pounds
The species is bluish to greenish with a darker pattern of dark oblique wavy lines and spots on the upper half of the sides and upper body and pale below. Side of the body is silvery white; the back has a moth-shaped dark spots of black tinged with blue-green on the upper sides and spots below under the lateral line. They have some black spots on side and marks southern mackerel chub mackerel there is no black spot on side of body width is narrow, cross-section of the body. The head and sides are silver-white, and there is a series of bars and dots along the side. Young fish have a dark pattern of reticulations on the upper sides that become less distinct as the fish ages.
The Blue Mackerel are occurring in coastal waters and also in oceanic waters preferring the cooler areas often forming into large surface schools. They enter coastal bays, harbors, inlets and estuaries with an attraction to wharves, jetties, shallow reefs and sand flats. They found in outside oastal waters tend to school over reefs areas, around islands and headlands. Large schools of adult fish are common in deep offshore waters at depths of 40-200 m in the south where they can be found extending out to the continental shelf. Juveniles are found inshore. They schooling by size often among schools of Jack mackerel, Trachurus declivis and Pacific sardines.
Blue mackerel are plankton feeders filtering copepods and other crustaceans. They eat whale feed or krill (shrimps), small bait fish such as anchovies and sprats, and squid. These prey animals are seasonally and locally abundant. Blue mackerel schools are pelagic hunters that migrate long distances and so can be plentiful or absent dependant on the availability of prey.
Spawning occurs in summer, particularly in the Bay of Plenty, outer Hauraki Gulf, and off Northland. Eggs are pelagic and spherical, 1.0-1.3 mm in diameter, and have a single oil globule 0.22-0.38 mm. Larvae stayed in coastal waters from May to September. Larvae have elongated to moderate body. Head moderate to large. Mouth is slightly subterminal from flexion stage. Villiform teeth are along both jaws by 3.2 mm. Low, smooth supraocular and supracleithral ridges in postflexion larvae. Gut moderate to long, coiled and voluminous. Large gap between anus and origin of anal fin, reduced as anus migrates posteriorly.
Blue mackerel are an oily fish with a high fat content. The flesh is dark but lightens when cooked. The high oil content makes it is an excellent fish for smoking. Even though mackerel is not considered to be a good eating fish, it is an excellent bait, especially for Mulloway or Jewish fish. They make excellent cut baits for groper and trumpeter.
Blue mackerel are strong fighters when caught on light rod and line, pulling much like a kahawai when hooked deep. Most of the blue mackerel are caught on jigs and flasher rigs. When a school is located feeding on the surface or on the sounder, drop your jig and flasher straight down until the fish strike. When using a baitfish rig, once a fish is hooked up, try leaving the rig in the water. The erratic motion of the hooked fish tends to excite the other fish to strike. When they are on the bite you can get as many mackerel on your flasher rig as you have hooks!
The best fun is to fish on light spinning gear (4 or 6 lb line) and a light rod. Like all mackerels they will readily take just about any lure fired into, or near, the school of mackerel. Small jigs (40g), bullet heads, and hex wobblers all work well. They can also be brought and held near the boat with a steady stream of barley so you can use your fly rod with a sinking line and a deceiver pattern.
They often come onto the bite at mid-morning and early afternoon. When boat fishing, they are often taken at estuary mouths over shallow waters outside reefs and sand flats. The Blue mackerel is known as a voracious and indiscriminate feeder; they will devour microscopic plankton and krill, live anchovy, engulf dead cut bait, and strike readily on lures and other flies. When schooled and in a feeding frenzy, they will strike at non-food items such as cigarette butts and even bare hooks.