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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.
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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.
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Description
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
Vertebrae: 31
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.
Habitats
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:
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.
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