history of sea fish?

Answer 1

Hi subodh g!you have asked an excellent
question.
Stanley millers was a greaat scientist.He conducted experiments to show how simple life forms originated on the earth.
He devised a special apparatus in which prebiotic conditions were created.Using this apparatus for several times,when this experiment was conducted for several times,it was observed that the water contained several sugars,amino acids,nucleic acid bases.
During the time of formation of the earth,earth was very hot due to the absence of oxygen and ozone.The little water present on the earth's surface evaporated.Due to this the water vapour condensed.Rains started coming.These rains washed all the salts present on the earth's surface and pooled down into oceans.This oceanic water contained certain chemicals which were essential for the appearence of the life in the water.In this way the organisms emerged in the sea water and in the ocean water.This is how the life was formed.This is called primordial or prebiotic soup.

Answer 2

In all the oceans of the world, fish have abounded for countless millennia, most of them doomed to spend their whole lives swimming until they are eaten by bigger fish. Shakespeare put it well when he had the Third Fisherman in Pericles ask how the fishes live in the sea, to which the First Fisherman replies: "Why, as men do on land; the great ones eat up the little ones." Only a tiny minority of fish are sufficiently large or well protected to escape predators. Even they may fall prey to the latest predators to arrive on the scene—to wit, ourselves.

Until human populations began to increase at an exponential rate, and until methods of preserving and transporting foods approached their present level of sophistication, mankind's need for food had little impact on the vast resources of the oceans and seas.

Radical change in this situation began in medieval times, when European fishing boats reached the rich codfishing...

Answer 3

once upon a time, the sea fish came to live in the waters of the pacific ocean, from then on it move from one continent to another.

Answer 4

very difficult to know

Answer 5

god created them

Answer 6

Probing fish history

By Steve O'Neill
A high-tech process developed for geological analysis has become an important tool in fish management and conservation.

U of G's Physics Department houses Canada's only scanning proton microprobe. Invaluable to geologists, the microprobe works by focusing a proton beam on a mineral specimen, which causes X-rays to be emitted by the specimen. This provides accurate analysis of concentrations of elements in the specimen down to very low levels and can provide color maps showing elemental distribution. The microprobe has applications in soil analysis, ore refinement and other geologically important work.

And now the microprobe is being used to trace the migratory habits of fish, says physics professor J.L. (Iain) Campbell, who is also U of G's provost and vice-president (academic).

It's all based on the fact that within the inner ear of the teleost order of fish -- including cod and char -- there's a tiny structure made of calcium carbonate, called an otolith. Each year, the otolith develops another layer of calcium carbonate. Like counting the rings of a tree, scientists can look at the otolith of a fish and determine its age.

Along with the new layer of carbonate, the otolith picks up trace levels of environmental elements each year. One of those elements is strontium, found in abundance in sea water but in relatively low levels in fresh water. When a fish spends part of a year in the strontium-rich environment of the sea, strontium levels in that year's otolith layer increase -- and can be detected with the microprobe.

"By scanning the otolith's growth rings with the microprobe, we can identify the high-strontium level rings, indicating which years, if any, the fish went to sea," says Campbell.

That's particularly important for arctic char, which can't overwinter in the frigid environment of sea water. So, depending on "morphotype" or subspecies, they either spend their entire lives in fresh water or migrate back and forth between the two. For management purposes, fisheries scientists need to know which populations of char are anadromous (migrating) and which are non-anadromous. In a test that takes less than half an hour, Campbell can use the microprobe to analyse the otolith from a sample fish from any given population and tell whether or not that fish migrates. Using the sample fish as models, fisheries scientists can make extrapolations about the migratory behavior of entire populations.

Applying the microprobe method to char populations has already yielded some interesting results. Scientists monitoring char in the ocean-connected Lake Hazen, located on Ellesmere Island in the Canadian Arctic, detected two morphotypes of the fish, one large and one small. Scientists had believed that the larger morphotype was anadromous, but Campbell disproved that theory by analysing strontium levels with the microprobe. Neither morphotype was found to migrate.

"This method allows us to map a fish's complete migratory history," says Campbell. "The correlation between the strontium levels in fish and those found in geographical regions also allows us to match fish with their point of origin."

This research was a collaborative effort involving Campbell, geological scientist Norman Halden of the University of Manitoba, Department of Fisheries and Oceans (DFO) scientists John Babaluk and Al Kristofferson, and microprobe manager Bill Teesdale. Special software for automating the analysis was developed at U of G by John Maxwell of the Department of Physics. Research support was provided by the DFO and the Natural Sciences and Engineering Research Council.


Shore enough


By Kerith Waddington
Guelph team is looking at the point where two distinct ecosystems meet -- the shoreline of a lake.

Profs. Andy Gordon, Narinder Kaushik, Steve Marshall, Environmental Biology, and Ron Brooks, Zoology, are using Algonquin Park's Scott Lake as a model for their research into interactions at the aquatic/terrestrial junction.

The shoreline is an area of high biodiversity. Wood and leaves that fall into lake water supply nutrients, shallow water allows sunlight to support bottom dwelling plants which in turn provide food, habitat and water oxygenation. Some terrestrial insects are an important food source for fish, and some aquatic insects that emerge as adults are eaten by land animals and birds.

The researchers are examining the energy flow between the two ecosystems. They believe that by understanding how the shoreline cycle works -- and is affected by practices like logging or shoreline development -- similar symbiotic ecosystems can be better maintained in the face of a changing global environment.

The team is looking at the long term implications of aquatic/terrestrial interactions: the project will be ongoing for the next 15 years. It's supported by the Ontario Ministry of Natural Resources, Ontario Graduate Scholarships and the Environmental Youth Corps program.

Fishing for trouble



By Jo-Ella Van Duren
llegal fishing and the resulting depletion of stocks will remain until government bodies improve regulatory enforcement, says a U of G economist.

Prof. William Furlong has spent more than five years analysing data on how strictly eastern Canadian fishers follow Department of Fisheries and Oceans (DFO) regulations. His conclusion? Quite simply, the potential benefits make breaking the law worth the risk for many members of the fishing industry.

"The problem here, as with many types of regulations, is that there is incentive for the individual to violate regulations for personal monetary gain," says Furlong.

He based his analysis on interviews with more than 3,000 East Coast fishers in Quebec and the Gulf of St. Lawrence region. The interviews were conducted by an independent consulting firm based in Halifax, with a guarantee of full confidentiality from the DFO.

Furlong believes a big part of the problem is that fish stocks are a freely accessible public resource with instant returns; the catches can be easily sold with only the fishers knowing they were illegally obtained. In addition, people fishing illegally don't always realize that they're threatening stocks and -- ultimately -- the economic well-being of their community, he says. The effects of their actions on stocks aren't immediately visible.

Furlong says some fishers are also skeptical about government estimates of the size of stocks because the overall distribution of fish is not always consistent with local catches.

Although most fishers are law-abiding, some will go to great lengths to outwit enforcement officials, he says. DFO officers in Caraquet, N.B., for example, discovered they were being followed by people with cellular phones, who were reporting the officers' movements to accomplices poaching at sea. In the same region, DFO officers began marking lobsters found in illegal traps with invisible ink, so they could identify violators when the fishing boats reached port. Many violators foiled that measure by checking their catch with the same black lights the officials were using and returning any marked lobsters to the water.

Although Furlong admits that cases like these involve only a minority of fishers, he is cautionary about the regulatory process. He says regulations are often devised without foresight into how effectively they can be enforced and at what cost.

Most important, penalties for violators who are caught don't always correspond with the potential gains, he says. The additional income from fishing illegally can exceed the cost of fines and equipment seized by enforcement officials. If, for example, the fine for an offence is $1,000, but there is a 0.001 chance that the violator will be caught, the expected price of each offence is, in economic terms, only $1. Furlong says that unless that changes, illegal fishing will continue.

"As it stands now, the potential gains generally exceed the potential penalties," he says. "I have recommended that fines for some violations be raised to increase the risk for illegal fishing. In other cases, the penalties are already severe, but the likelihood of detection and prosecution -- actually paying the penalty -- is minimal. That also needs to change."

Furlong says his research is unique in that it examines the motivations of violators, as opposed to other studies that base recommendations for fish-stock controls solely on biological data.

"Regulations have generally been constructed in response to biological reports," he says. "Examining them from an economic perspective increases our understanding of how to make them more effective through improved regulatory design and by limiting incentives to violate."

This research was sponsored by the DFO.