Some fish may be mature in the middle of Marchin Iranian waters.
Eggs in fish taken in November and January are small sothe breeding season is deduced to be around March.
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Age and growththEssentially unknown although fish are larger later in the year (11.8-31.4 mm standard length in January and 15.6-34.7 mm in March).
The velar skeleton of the ammocoetes larvae of lampreys has both internal and external components that bear on the issue of gnathostome branchial arches.
As noted in the gill arch overview, ..
Most of these winter records have been based on odd fish only, i. e., not enough to suggest the presence of any great concentration of mackerel. But there were enough of them off New York in January, February, and March of 1949 for commercial fisheries to bring in what Gordon has characterized as "huge amounts." He also reports "a large body of fish" off Montauk in mid-February of 1950. Schools of "mackerel" have also been reported as sighted at the surface on several occasions in winter, but none of these seem to have been brought in.
It has been a commonplace from the earliest days of the mackerel fishery that the fish are fat when last seen in the autumn, but that most of them are thin when they reappear in spring, obviously suggesting that they feed little during the winter. This is corroborated by the fact that the mackerel taken on bottom by British and French trawlers between December and March usually are empty, and that a few mackerel taken by the along the continental edge off Chesapeake Bay in February 1931 were very emaciated. But mackerel taken in winter sometimes have food in their stomachs; some of them even are fat.
The gills are mounted on bony structures called gill arch.
Of special note to psychophysiological processes, the third gill arch alsogives rise to the carotid body, containing peripheral chemosensitive receptors sensitive to oxygen and carbon dioxide levels,(Warwick & Williams, 1975).
Although the trigeminal and facial nerves originate from branchialarches and have communications with the other three cranial nerves originating from the branchial arches, the source nucleiof the special visceral efferents for the glossopharyngeal, vagus, and accessory nerve originate in the same medullarynucleus, the nucleus ambiguus (NA).
Metaspriggina had bones called gill arches to support its gills.
Shared developmental mechanisms pattern the …
Gill rakers 9-16,mean 11, on each arch, triangular in shape with 3-4 spines at the topof each raker (Barak ., 1994).
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Accounts of Smith's searches for cave fishes in Iran are given in his two books (Smith, 1953; 1979).
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By 15 March, eggs in a 49.7 mm standard length fish are 1.3mm in diameter and well-developed.
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It has been common knowledge since early colonial days that mackerel fluctuate widely in abundance in our Gulf from year to year, perhaps more widely than any of our other important food fishes, with periods of great abundance alternating with terms of scarcity, or of almost total absence. In good years the fish may appear in almost unbelievable numbers; schools or associations of schools, miles in length, are reported; and it is common to see 50 or more separate bodies of fish from the masthead at one time. Mackerel, in short, seem to be everywhere, and a tremendous catch is made. But perhaps only an odd school will be seen here and there the next year, and the fishery will be a flat failure.
From shark gills to human limbs
The period from 1825 to 1835 was one of abundance. In 1831, for example, more than 380 thousand barrels (76 million pounds) of salt mackerel (in those days most of them were salted) were landed in Massachusetts ports. But mackerel were scarce for the next 8 years (1837-45), only 50,000 barrels being landed in Massachusetts in 1840. The Massachusetts catch then fluctuated violently from 1851, when the landings rose once more to 348,000 barrels, down to 1879. The fleet brought in something like 294 million fish from Nova Scotian and United States waters combined in 1880. And this introduced a period of extraordinary abundance, culminating in 1885 when the catch reached the enormous total of 500,000 barrels (100,000,000 pounds). But this was followed in its turn by a decline so extreme, so widespread, so calamitous to the fishing interests, and so long continued, that the catch was only about 3,400 barrels (equivalent to 582,800 pounds of fresh fish) for the entire coast of the United States in 1910 (when the stock of mackerel fell to its lowest ebb) with almost none reported in Massachusetts Bay or along the Maine coast.
'Sonic hedgehog' gene revives an old idea ..
The European mackerel usually keep to the bottom on their spring migration until close in to the land before rising to the surface. But this generalization does not apply to the American fish, for while some may swim deep (so, only can we account for the fact that the first schools often show as early in Massachusetts Bay as on Georges Bank or off Nantucket) mackerel in great numbers are first sighted 30 to 50 miles offshore, and this all the way from the latitude of Cape Hatteras to the mouth of the Gulf of Maine. The first mackerel "show" off the Cape Hatteras region at any time between about March 20 and April 25, usually early in April, and by the middle of April off Delaware Bay. As the water warms they spread northward and shoreward, being joined, it seems, by additional contingents from offshore. They reach the offing of southern New England some time in May, and they are plentiful on Nantucket Shoals by the first week of that month, as a rule.
The Evolution of Paired Fins (PDF Download Available)
Various far-fetched explanations have been proposed for these astounding ups and downs in the catches from year to year, such as that the fish have gone across to Europe; have sunk; or have been driven away or killed off by the use of the purse seine. Actually, these changes reflect the ups and downs in the numbers of the fish that are in existence from year to year. Mackerel, in short, were extremely plentiful in 1885, very scarce in 1910, moderately plentiful in 1916 and 1917, very scarce again in 1921, and they have been moderately plentiful since about 1925, but probably not so plentiful as they were in the 1880's.
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