Do
fish drink water? An
oft- repeated question about the fact regarding fishes living in water is ’Do
fish drink water’. Many of us are curious to know the reply.
The
answer is “Yes” & ‘No”
While the freshwater fish doesn’t drink water- the marine fish drinks
large quantities of water.
Since the liquid in a freshwater fish’s body is
saltier (dense) than the
surrounding water, the freshwater fish is in constant danger of soaking up water and swelling. As a result
it doesn’t drink water and what ever water enters in fish body through skin
& gills is carried to the kidney and used to flush out waste products in
large quantities of urine.
The marine (Salt-water) fish has exactly the opposite problem
Salt-water fish’s liquids are less salty (dense) than surrounding water and fish is in constant danger of
dehydration. Thus the salt-water fish have to drink large quantities of water
to make up for what it loses through its gills & skin. Some of the salt
that it receives goes through the digestive tract and is excreted. While
some salt that it receives is passed
through special gill cells back into the ocean. A salt-water fish seldom urinate.
How Fishes Swim?
Though shapes of fishes differ
widely but in general they are boat shaped which facilitate their movement in
water.For
a fish to move through aquatic medium,
which is
incompressible, it actually push it aside. The fish can do this by wiggling
back & forth in a snake like motion, pushing water aside by the forward
motion of its head,
first to the left than do the right, also with the curve of its body and
finally with its flexible tail. The water, tending to return to its original
position, now flows back along the fish’s
narrowing side, closing in at the tail and helping the fish to move forward.
Skate and rays move by undulation of their greatly enlarged sidefins, which gives
them appearance of flying through water some flattened fish crawl
on the bottom like sea
robin while some
crawl right out of the water on the beach like mud skipper. The climbing perch
and snakehead travel overland from pond to pond on their forefins. Some
fishes can fly in the air. They can skim
above the water for nearly a minute and if there is good breeze to lift them
up they may
reach a height of 10-20 feet,planing
from wave to wave with their greatly extended forefins held rigidly out like
wings.
How A Fish Sees?
Most
of us are aware that seeing under water is a different matter from seeing in
the air. Light is diffused and quickly fades to a dim twilight zone. Even in
clear water only relatively close objects can be sharply focussed. But
this is the environment, the eyes of fishes must cope with, and
their adaptation to the medium is extremely ingenious. Their primary need
is to see movements and nearby shapes- and this they do to perfection with
their eyes set on the side of their head, many of the fishes can practically
register every thing that moves around them at any time. Needing no eyelids or
tear ducts in their liquid medium, they have evolved ways of coping with
varying amount of light.
The
eyes of most of the fishes are placed so widely apart that they are considered
to have monocular vision viz. each eye collects a separate un- coordinated
image, which overlaps the least. In addition, the retinas of a fish pass
impulses only to the side of the brain, opposite the eye, enhancing the
monocular effects. Compared to this man has a double advantage his eyes are
placed in front of his head giving him a wide field of overlapping vision.
Man’s eyes sends simultaneously impulses along nerves to both sides of the
brain, resulting in true binocular
vision.
Some
fishes have another remarkable feature of having ‘Divided Vision’. Fish
like Anableps is adopted in seeing
above a below the surface. Each eye of this ‘four eyed fish’ is situated
on top of the head in such a way that it can swim with half of the eye out of
water, often ducking in water or moistening the eyeball.
We
can find age of fish by reading its Scale
From
head to tail, fishes are generally covered by flexible armour of rounded
overlapping plates called Scales.
These are embedded in the inner layer of the skin and form an important
covering. In addition to this, fishes are further protected by a layer of
mucous slime produced by numerous invisible glands scattered all over the
body, this mucous in antiseptic helping to ward off bacteria and fungi as well
as lubricating agent.
In
size and thickness, scales may vary greatly, from those of mahseer, which is reported to have scales (Fish size over 12 feet)
as large as man’s head to the microscopic one of common eel. Few fishes
especially catfishes have no scales at all. In some fishes like trunk-fish,
scale are fused to form an inflexible box like covering or in pipe-fish and
sea horse, rows of connected bony plates.
Scales
also grow along with the fish and especially in fishes of temperate zone leave
a distinctive record of age and season. Since in the temperate zones, each
scale grows fastest during the summer, when the fish is getting the maximum
feed and this make possible to tell a fish age by counting growth rings on
scale. Regarding typology, fish scales are categorized in four types. The
primitive placoid scales found in shark, rays and skates are tooth like
structure size of grains embedded on sand paper.
Ganoid
scales are present in few bony fishes. These are diamond shaped and attached
to each other by joints. These are coated with ganoin a substance, which gives
the fish appearance of polished ivory.
The
most common scales are cycloid and ctenoid. The former has a comb like edge
while the later has a rounded border. Most fishes have one or the other types
of scale. They are arranged in over lapping rows and as they are thin light
and flexible, most fishes that have them are fast swimmers.
Fatty
fish intake may lower mental decline
A new study has found that fish fat
intake may play a role in brain functioning in middle age. According to a
report in Health Scout, the study o 1,613 men and women between the ages of 45
and 70 in the Netherlands, which has a high diet in fish, found the type of
fat consumed plays a role in a person’s mental flexibility, speed and
overall functioning. Fatty fish include mackerel, salmon trout herring and
other Coldwater fishes, which are found in the icy waters off the northern
European coastline.
Researchers from University Medical
Center Utrecht found people who ate lots of foods rich in omega-3
polyunsaturated fatty acids and consumed lots of fatty fish generally had a
lower risk for impaired brain functioning (19% less) and speed (28%), compared
to those who didn’t follow a similar diet.
‘We
used really sensitive cognitive tests, and it surprised me that already at
that age you could see the association between diet and mental agility’,
said Dr. Sandra Kalmijn, of the Julius Center for Health Sciences and Primary
Care/ ‘It convinced me and reinforced for me the link we saw between lots of
fish and cognitive function’. Conversely, those with diets high in
cholesterol were found at a ‘ significantly’ increased risk of impaired
memory (27% higher) and flexibility (26higher). The findings appear in the
latest issue of Neurology.
Because a decline in mental skills can
appear decades before the onset of Alzheimer’s disease, the study says
it’s important to examine the effect of diet on cognitive functioning in
middle age (ANI).
The Tribune
4th February 2004
Fish
as multi doctor
Take fish to enrich your BRAIN
It is widely believed that countries or
communities who have a lot of fish in their diet are more intelligent than the
others. Sounds fishy? But it may well be true. Researches have shown that
certain nutrients that are vital for the development of one’s brain are
found in very high level in oily fish. The brain has large amounts of a fatty
acid known as decosahexaenoic acid (DHA), but unfortunately the human body is
incapable of producing this fatty acid to the quantity that the brain
requires. This is usually supplemented by including meat, eggs and fish,
particularly the oily ones, which are very high in DHA. Mackerel, sardines,
herring, and tuna are very high in DHA, whereas in fish like cod, plaice, and
monkfish, this is found only in their livers.Fish are rich in eicosapentaenoic
acid (EPA) and docosahexaenoic acid (DHA) and it is these polyunsaturated
fatty acids, which provide the key. It is suggested that the minimal dietary
requirement for EPA and DHA should be about 200 mg/day and this amount can
easily be obtained from eating fish just once a week In extensive researches
done on primates and rats fed on food, rich in DHA, it has been found that in
all cases the learning abilities improved. Certain rise in visual awareness
was also noticed. From such experiments it has been concluded that DHA
improves eyesight, blood circulation and skin and reduces pain such as in
rheumatoid arthritis.
Take fish to protect your HEART
At one of the annual American Heart
Association meeting in New Orleans, the Brigham and Women's Hospital doctors
presented their findings, which said that Omega-3 fatty acids found in
so-called fatty fish such as the salmon, mackerel, tuna and sardines, seems to
get into the tissues and arteries and aids in protecting the heart. They said
that eating fish at least once a week could cut the chances of dying suddenly
from heart failure into half. These findings were based on researches followed
on more than 22,000 male physicians for 12 years. It was found that those who
ate at least one serving of fatty fish a week reduced their chances of cardiac
arrest by 50 percent. However, although consumption of fish was said to aid in
reducing the risk of sudden death, it did not seem to change drastically with
the increase in consumption. In other words, although eating fish once a week
seemed to work, eating it more often did not work better. The Omega-3 fatty
acids protect the heart in several ways. From keeping the heart beating too
fast, they prevent the formation of blood clots and also prevent the buildup
of plaque in the heart arteries.
Take fish to control Blood Pressure (BP)
Eating
fish regularly with omega 3 polyunsaturated fatty acids is said to
significantly lower blood pressure in people suffering from hypertension.
According to a group of doctors from John Hopkins Medical School, USA, 3 grams
or more per day of fish oil (6-10 capsules) lead to reduction in the blood
pressure in hypertensive individuals, lowering systolic pressure by an average
of 5.5 mm Hg and diastolic pressure by 3.5 mm Hg. It is more effective in
individuals who have really high blood pressure and not in the ones having
normal BP.
Take fish to protect your self from Cancer
Scientists
are now saying that including fish in your diet may even prevent certain types
of cancer. Although not yet conclusive as far as humans go, studies in animals
have found that those same fish fats rich in omega-3 fatty acids suppress
cancer formation
So next time you plan your menu, be sure to add fish in it, at least once a
week.
Fish - How Good Are They For Us
Fish
is one of the most popular food items of the non-vegetarians. It is
nutritionally rich and tasty. Fishes varies in shape, size, colour, skin,
bone, and taste. It is unique animal meat that is rich in essential fatty
acids. They contain protein and many other major nutrients. Fish is a staple
food in many parts of India and Japan.
The taste of fish depends upon its origin, whether from salt or fresh water,
its fat content, and whether it is eaten fresh or preserved. I doubt there are
any other food items those are cooked such a varied ways and eaten. Fresh fish
is taken as steamed, baked, boiled, as various curies, roast, fries, grills,
pickles, cutlets, finger chips, biriyani etc. Among this curries and fries are
the most popular Indian preparations. Dry fish is taken as fries, chutney, and
also in powder form.
Fish is a good source of proteins and it
constitutes about 17 - 20 %. Fish proteins are good sources of all essential
amino acids. Fish protein beings rich in lysine and threonine supplement
effectively with cereal proteins. Small fish eaten along with bones are a rich
source of calcium. The caloric value of the edible portion depends upon its
fat content and thus on the season. During the spawning season the fat content
may rise and the caloric value increases. Studies have proved that eating fish
decrease heart disease.
Scientists
have also discovered that omega 3 fatty acids are essential for the healthy
development of the eyes and brain. Fish has been described as a food for the
brain but there is no reason to believe that a fish eating population is in
any way mentally superior to those who do not eat fish or those who are
vegetarians.
Fish
is a rich source of long chain n-3 PUFA which are biologically more active
than their parent member namely alpha linolenic acid in producing several
health benefits. Those who have a taste for fish are advised to take about 100
- 200 gm of fish twice a week. Fish oil capsules that containing large
quantity of long chain n-3 PUFA are used in the treatment of
hypertriglyceridaemia, thrombosis, and inflammatory diseases. Oily fish such
as mackerel and trout have been shown to relieve some symptoms of psoriasis
and should form a regular part of those patients diet. This may be due to the
omega 3 fatty acids or to the large amounts of vitamin D present in it.
Salt-water
fish is rich in iodine, phosphorous and calcium. Those who eat regularly
salt-water fish generally will not have these mineral deficiencies. Fish also
contain mineral copper. Vitamin A and D is also present. The oil from shark,
cod, and halibut liver is very rich in these vitamins.
Search
byte- for expecting mothers
According to university of Bristol, consumption of fish
in later stages of pregnancy prove to be very potent in innate development of
baby. Research has proved that the presence of omega-3 fatty acid in fish
helps in the development of the nervous system (brain) of the child. Reason
behind it is the enhanced blood circulation aids in increased blood supply to
the placenta due to which fetus derives more nourishment from maternal blood.
Fish
oil source of instant energy
Fish oils
are available in capsule and liquid form. The cod liver oils are derived from
cod and also from Pollock, satire, and whiting. Fish oils are from fish liver
and fish body. The oil extracted from the fish livers is deodorised and then
vitamin E and antioxidants are added to prevent it from going rancid.
The
oil is an excellent source of vitamin A and D. Two teaspoons of cod liver oil
provide about 1200ug of vitamin A, 20ug of vitamin D and about 2gms of omega 3
fatty acids. Because of high concentrations of these vitamins, cod liver oil
has been used to prevent and treat conditions such as xerophtalmia; an eye
disease caused by vitamin A deficiency and rickets a bone disease caused by
lack of vitamin D. Shark liver oils also contain squalene, which is utilised
by the body to produce cholesterol. Glyceryl, a substance present in shark
liver oil ethers may help to protect against cervical cancer. Fish body oils
contain less vitamin A and vitamin D but are rich in omega fatty acids.
Fish Oil Fight Diabetes
April
23, 2002 -- A compound found in fish oil may help those at risk for type 2
diabetes stave off the disease. A new study shows fish oil supplements appear
to improve the function of insulin -- the hormone responsible for sugar
metabolism -- in overweight individuals.
Louisiana
State University researchers presented the results of their study this week at
the Experimental Biology 2002 conference in New Orleans.
About
17 million Americans suffer from type 2 diabetes, and 16 million may be at
risk of developing the disease in the next decade, according to government
estimates. The disease occurs when the body becomes unable to respond to
insulin, which causes blood sugar levels to rise to dangerous levels. It is
more commonly seen in overweight adults.
This
differs from type 1 diabetes, which is usually seen in children that aren't
overweight. But in recent years, doctors have been seeing more type 2 diabetes
in children due to the rising epidemic of obesity in the U.S.
The
study authors say previous research has shown that populations that eat a lot
of fish containing omega-3 fatty acids, such as tuna, salmon, and mackerel,
have lower rates of type 2 diabetes compared with those who eat less fish.
That prompted them to look at the effect of omega-3 fatty acids themselves on
how the body uses insulin.
Researchers
studied 12 overweight men and women aged 45 to 70 and gave them once-daily
supplements containing 1.8 grams of an omega-3 fatty acid known as DHA (docosahexaenoic
acid). All of the participants suffered from insulin resistance, a condition
in which the body doesn't respond normally to insulin and that often precedes
type 2 diabetes.
After
12 weeks, researchers found 70% of the participants showed a decrease in
insulin resistance, and in 50% of the patients that change was significant,
according to researcher Yvonne Denkins, PhD.
She
says the findings are only preliminary. Due to the small number of
participants in the study, much more information about the role of fish oil in
preventing diabetes is needed before any recommendations can be made.
Anyone
who is considering increasing their intake of fish oil with supplements should
first check with their doctor since DHA can have a slight thinning effect on
the blood.
In
addition, there are other proven ways to prevent type 2 diabetes in someone at
risk. Both exercise and the drug Glucophage have been shown to work in
preventing type 2 diabetes in people who are overweight and have high levels
of insulin in their blood.
Research shows that trout and other oil rich fish
can play a vital role in preventing deaths from heart disease- and yet most of
us fail to eat enough to do us good1.
Government health experts recommend that we eat
one to two portions of fish a week, one of which should be an oil rich fish
such as trout which is high in omega-3 polyunsaturated fatty acids2.
Research indicates that it can cut the risk of fatal heart attacks by lowering
blood fat levels and reducing blood clotting.
UK consumption, however, is very low, despite the
fact that coronary heart disease is the most common single cause of death in
the UK3. Figures from the British Nutrition Foundation show that
only a third of adults eat one small portion of oil rich fish a week. The
Institute of Optimum Nutritionists believes as much as 90 per cent of the
population is now deficient in Omega-3.
An average portion of grilled trout (flesh only)
is 1558, which provides 1.838 grams of Omega-31 - well within the
weekly health guidelines of 1.5g a week2.
It's low in fat (a third of the fat of salmon) as
well as being low in calories (just 135 kcals per 100g)2. It's an
excellent source of iron, calcium, selenium and vitamins A, B1, B2, B6 and B12
and contains valuable natural oils that can help keep the skin and hair in
good condition.
It's also extremely tasty - and convenient. A
delicious trout meal can take under 15 minutes to prepare and cook.
In addition to medical research into heart
disease, there is growing evidence to demonstrate the importance of Omega-3 in
brain and retina development in infants. Concern has been expressed about the
adequacy of Omega-3 in the diet of pregnant and breast feeding women1
Oil rich supplements have also been shown to
alleviate some of the symptoms of rheumatoid arthritis, producing beneficial
changes in levels of fatigue, swollen and tender joints, grip strength and
mobility1.
Because rainbow trout is mainly farmed, there is
year round availability in this country. Most supermarkets now carry a wide
range, including whole gutted trout, trout fillets, chunky fillets, hot and
cold smoked slices or fillets.
So don't miss out - pick up a trout and head for a
healthier lifestyle.
Sources:
1.
British Nutrition Foundation Conference, 1 December 1999
2.
Coma Report (Committee on Medical Aspects of Food Policy 1994)
3.
Diseases of the heart and circulatory system are the main cause of
death in the UK, accounting for 260,000 deaths in 1997.
EATING TROUT MAKES YOU BRAINY
Ever heard the Old Wives' Tale that eating fish makes you brainy? Well,
scientists today keep finding more and more evidence that it may be true!
Trout is packed with Omega-3 oils, which scientists say can improve your IQ!
60% of your brain is made of fat - and not
just any fat, but very special kinds of fat.
Trout is high in Omega-3 oils, which generally get called "Good
Fats" because they contain the stuff that helps your brain repair and
rebuild its brain cells.
Nowadays we eat very little food that's rich in Omega-3 oils, but to keep our
brains happy and working well, we need to eat food that contains a lot of
Omega-3.
Trout
is full of protein, which gives you energy (good for building muscles!)
Trout contains essential vitamins and
minerals
Trout is high in calcium (for healthy
bones and teeth)
Trout is rich in iron (for healthy red
blood cells)
Trout is rich in selenium (for a
healthy heart)
Trout is a great source of vitamin A (for healthy skin, and help resits
infection)
Trout is a great source of vitamin D
(bones and teeth again!)
Trout is low in saturated fat
Trout is high in Omega-3 oils
British Trout
Association, Bow Business Centre, London E3 2SE
Eating
Salmonid fish cures diabetes in women
A
study undertaken recently in HarvardUniversity revealed that the more fish a diabetic woman eats, the less likely she
is to develop heart disease.
Many
researches have touted the benefits of fish for preventing heart disease in
healthy women, notes the lead author of this study, Dr. Frank Hu, associate
professor of nutrition and epidemiology at the Harvard School of Public
Health. His group postulates that fish may benefit women with diabetes even
more, since these women face a greater risk of heart disease.
They
found that diabetic women who ate fish five days a week had a 65% lower risk
for heart disease than diabetic women who never ate fish. ‘Even for diabetic
women who ate fish once or twice a week, there was a 40% lower risk of heart
disease,’ Hu says.
The
study sample was 5103 female nurses diagnosed with Type 2 diabetes and free of
cardiovascular disease or cancer. Not only were reported fish eaters less
likely to develop heart disease but fewer of them died.
Not
all fish are created equal, Hu says. “ Dark-meat fish belonging to salmonid
family Salmon have more omega-3 fatty acids so they are probably more
beneficial’.
Source:
Reader’s Digest; 165:988:Aug.2004:28p.
Ten
Golden Rules for good fish health for observance by
Trout Farmers
1.Buy fish eggs or fingerlings with known health status
i.e. from a farm, which is under surveillance of Fish Health Services;
2.Keep an optimal density of
fish in the raceways 4-5 kg/m3 stocking density is generally the
optimum one;
3.The velocity of the water
should be double the length of fish being reared in the raceways;
4.Daily fish ration has the
direct relationship with water temperature. Over feeding may give birth to
severe diseases besides poor economics or even loses;
5.Good hygiene in the
raceways and their disinfections at proper intervals can save fish from
various diseases;
6.Ensure strict vigil on the
up stream water. It should be free from sewage and pesticide washings;
7.Avoid unnecessary stress
to the fish from handling. Treatment and shorting be done by experienced
/qualified hands;
8.Ensure regular health
control measures;
9.On any sign of disease
discontinue feeding and call for personal of Fish Health Service;
10.All in- all out system be
observed. Entire facility / raceways be emptied and disinfected before the
recruitment of fresh stock.
Fish
Oil Cures Brest Cancer
Omega-3
fatty acid present in fishes, which is useful for brain has now found capable
of formulating a potent medicine against breast cancer after it’s
amalgamation with an anesthetic, during recent studies conducted by a group of
scientists.
Researchers
from The Indiana University, New York have claimed formulation of an effective
medicine against breast cancer by mixing Omega-3 fatty acid with anesthetic
prophol. Both the components are capable of halting the multiplication of
cancerous cells. Apart from stopping the spread of cancer to other parts of
the body these also block the growth of secondary tumor. On the basis of a
study report published in journal of British’s Cancer Research the results
of the medicine formulated from these compounds against cancer are really
encouraging.
Dr.
Sara Rawling a researcher told that effects of two types of Omega-3 fatty
acids DHA & EPA have been studied. When these are mixed with prophol then
the results are encouraging. The use of this medicine not only stopped the
growth of cancerous cells but even some effected cells were destroyed.
Principal Scientist Dr. Rafat Siddiqui said on the basis of research results a
patch or ointment can now be formulated. He further said that there are now
plans to formulate large quality of this medicine for tests on animals. At
present the tests have been conducted on cancer effected cells and it can
hardly he stated that how much effective it would be on cancer effected
ladies. Omega-3 fatty acid is found in Tuna, Salmon, Hering, Sardins,
Mackeral fish species, which apart from keeping the brain fully toned also
controls the blood cholesterol level. Scientist even say that use of Omega-3
fatty acid in diet can save from Arthritis, Dermatitis and Asthma.
Courtesy:
AMAR UJALA
Global
collapse of fish species by 2048
With 29%
Species Already In Decline, Over-fishing And Habitat-loss Will Result In
Lesser Seafood: Study
Washington: The
world’s fish and seafood population will collapse by 2048 if current trends
in habitat destruction and over-fishing continue, resulting in less food for
humans, researchers said on Thursday.
In an analysis of
scientific data going back to the 1960s and historical records over a thousand
years, the researchers found that marine biodiversity-the variety of ocean
fish, shellfish, birds, plants and micro-organisms- has declined dramatically,
with 29% of species already in collapse.
Extending this pattern
into the future, the scientists calculated that by 2048 all species would be
in collapse, which the researchers defined as having catches decline 90% from
the maximum catch. This applies to all species, from mussels and clams to tuna
and swordfish, said Boris Worm, lead author of the study, which was published
in the current edition of the journal Science.
Ocean mammals, including
seals, killer whales and dolphins, are also affected.
‘Whether we looked at
tide pools or studies over the entire world’s ocean, we saw the same picture
emerging’, Worm said in a statement. ‘In losing species we lose the
productivity and stability of entire ecosystems. I was shocked and disturbed
by how consistent these trends are- beyond anything we suspected.’
When ocean species
collapse, it makes the ocean itself weaker and less able to recover from
shocks like global climate change, Word said. The decline in marine
biodiversity is largely due to over-fishing and destruction of habitat, Worm
said in a telephone interview from DalhousieUniversity in Halifax, Nova
Scotia.
The loss of biodiversity
makes ocean ecosystems loss able to recover from the effects of global climate
change, pollution and over-exploitation, Worm said.
He linked a diverse
ocean environment to a diversified investment portfolio. With lots of
different species in the oceans, just as with lots of different kinds of
investments, ‘You spread the risk around,’ Worm said. ‘In the ocean
ecosystem, We’re losing a lot of the species in our stock portfolio, and by
the we’re losing productivity and stability, by losing stability, we’re
losing the ability of the system to self-repair’.
This research shows we’ll have few viable fisheries by 2050,’ Andrew
Sugden, international managing editor of Science, told reporters at a
telephone news briefing. “This work also shows that it’s not too late to
act.”
To help depleted areas
rebuild, marine-life reserves and no-fishing zones need to be setup, Worm and
other authors of the study said. This has proven effective in places including
the Georges
Bank off the
US Atlantic coast, he said. With marine reserves I place, fishing near the
reserves can improve as much as four-fold, Worm said.
Beyond the economic
benefits to coastal communities where fishing is a critical industry, there
are environmental benefits to rebuilding marine biodiversity, the scientists
said. Depleted coastal ecosystems are vulnerable to invasive species, disease
outbreaks, costal flooding and noxious algae blooms, they reported.
Certain kinds of
aquaculture can also be beneficial, according to the scientists. REUTERS
Courtesy: The Times Of India4th November 2006.
November 03, 2006
Losing species
Its findings are startling. A global study lead by
Dalhousie’s Boris Worm shows current trends projecting the collapse of all
currently fished seafoods before 2050. The international group of ecologists
and economists show that the loss of biodiversity is profoundly reducing the
ocean’s ability to produce seafood, resist diseases, filter pollutants,
and rebound from stresses such as over-fishing and climate change. The
study, published in the November 3rd issue of the journal Science, reveals that every species lost causes a faster
unraveling of the overall ecosystem. Conversely every species recovered adds
significantly to overall productivity and stability of the ecosystem and its
ability to withstand stresses.
“Whether we looked at tide pools or studies over
the entire world’s ocean, we saw the same picture emerging,” says Dr.
Worm. “In losing species we lose the productivity and stability of entire
ecosystems. I was shocked and disturbed by how consistent these trends are
– beyond anything we suspected.”
The four-year analysis is the first to examine all
existing data on ocean species and ecosystems, synthesizing historical,
experimental, fisheries, and observational datasets to understand the
importance of biodiversity at the global scale.
Every species matters
The results reveal global trends that mirror what
scientists have observed at smaller scales, and they prove that progressive
biodiversity loss not only impairs the ability of oceans to feed a growing
human population, but also sabotages the stability of marine environments
and their ability to recover from stresses. Every species matters.
The good news is that the data show that ocean
ecosystems still hold great ability to rebound. However, the current global
trend is a serious concern: it projects the collapse of all species of wild
seafood that are currently fished by the year 2050 (collapse is defined as
90 per cent depletion).
Collapses are also hastened by the decline in
overall health of the ecosystem – fish rely on the clean water, prey
populations and diverse habitats that are linked to higher diversity
systems. This points to the need for managers to consider all species
together rather than continuing with single species management.
Fundamental change needed
“Unless we fundamentally change the way we
manage all the oceans species together, as working ecosystems, then this
century is the last century of wild seafood,” says co-author Steve Palumbi
of StanfordUniversity. The impacts of
species loss go beyond declines in seafood. Human health risks emerge as
depleted coastal ecosystems become vulnerable to invasive species, disease
outbreaks and noxious algal blooms.
Many of the economic activities along our coasts
rely on diverse systems and the healthy waters they supply. “The ocean is
a great recycler,” explains Palumbi, “It takes sewage and recycles it
into nutrients, it scrubs toxins out of the water, and it produces food and
turns carbon dioxide into food and oxygen.” But in order to provide these
services, the ocean needs all its working parts, the millions of plant and
animal species that inhabit the sea.
The strength of the study is the consistent
agreement of theory, experiments and observations across widely different
scales and ecosystems. The study analyzed 32 controlled experiments,
observational studies from 48 marine protected areas, and global catch data
from the UN’s Food and Agriculture Organization’s (FAO) database of all
fish
and invertebrates worldwide from 1950 to 2003. The
scientists also looked at a 1000-year time series for 12 coastal regions,
drawing on data from archives, fishery records, sediment cores and
archeological data.
Can losses be reversed?
“We see an accelerating decline in coastal
species over the last 1000 years, resulting in the loss of biological filter
capacity, nursery habitats, and healthy fisheries,” says co-author Heike
Lotze of Dalhousie who led the historical analysis of the Bay of Fundy, Chesapeake Bay, San FranciscoBay, and the North Sea, among others.
The scientists note that a pressing question for
management is whether losses can be reversed. If species have not been
pushed too far down, recovery can be fast — but there is also a point of
no return as seen with species like northern Atlantic cod.
“The data show us it’s not too late,” says
Worm. “We can turn this around. But less than one per cent of the global
ocean is effectively protected right now. We won’t see complete recovery
in one year, but in many cases species come back more quickly than people
anticipated — in three to five to 10 years. And where this has been done we see
immediate economic benefits.”
The study was based at the National Center of
Ecological Analysis and Synthesis (NCEAS), funded by the National Science
Foundation, the University of California and UC Santa
Barbara.
What is a fish
A fish is a cold-blooded aquatic vertebrate, which swims with the help of
paired fins and breathes through gills. Fish constitute about half of all
known vertebrate species.
What is a person who studies fish called:
An ichthyologist.
How are fish identified: A combination of the number of
characteristics such as position of mouth, scale counts, general features,
colour, maximum length and distribution are used idendification.
Difference between male and female fish
- In some species the males and females have different shaped bodies or
different colouring; in other species there is no visible difference and its
appears at the time of breeding season.
How fishes breathe: Some fish have lungs and breathe air, but
most breathe through gills. Gills are made up of thin sheets of tissue
richly supplied with blood vessels. As water passes over them dissolved
oxygen is absorbed into the blood and waste products such as carbon dioxide
pass out into the water. The gills are protected by a large bony plate
called an operculum.
What is a lateral line: The lateral line is a row of scales
that most fish have along their sides, stretching from their head to tail.
Under these scales are a system of fluid-filled canals and specialized
cells, which transmit vibrations to the brain. The lateral line helps fish
to detect objects including predators and prey.
Why are fish slimy: Fish secrete a type of mucus from their skin.
This slime coating is important because it provides protection against
parasites and diseases, covers wounds to prevent infection and helps fish
move through the water faster. Some species release toxins in their slime
which ward off attacking creatures while others use their slime to feed
their young.
What do fish eat? Fish Diet: Detritus, diatoms, aquatic
macro-invertebrates (particularly insect larvae, crustaceans and worms),
molluscs, aquatic plants, algae, zooplankton, fish and their eggs,
terrestrial insects, water birds, turtles, frogs, snakes and mice etc.
What eats fish: Other fish, birds (e.g. pelicans, cormorants
and herons), snakes, turtles, crustaceans, some insect larvae (e.g.
dragonfly larvae), and humans. In other parts of the world there are also
animals such as wild cats, wild pigs and bears that feed on fish.
Where do freshwater fish live:
Freshwater fish inhabit all sorts of environments: streams, rivers, lakes,
springs, lands, lagoons, billabongs, backwaters, estuaries, swamps, dune
lakes, reservoirs, ponds and drains. Some freshwater fish also spend part of
their lifecycle at sea.
Types of Tropical fishes:
Anabantids - The Anabantids are fishes that belong to the families
Anabantidae, Belontiidae, Helostomatidae and Osphronemidae. They are also
called "labyrinth fish" because of their auxillary breathing organ called
"labyrinth".
Catfishes-
Catfishes are indentifiable by the barbels around their mouths which allow
them to locate food in the dark. Instead of scales, the skin may be naked or
covered with bony plates ("scutes").Types: Mystus seenghala, W. attu, H. fossislis, Clarias batrachus
etc.
Cichlids - Description - The colours, shapes and sizes of cichlids vary
enormously. Types:
Angelfish
Cyprinids - Description - Tropical aquarium cyprinids are divided into three main
groups: barbs (which are carp-like fishes), danios and raspboras. All
cyprinids spawn through egg-scattering.
Loaches - Description - Loaches are distinguishable by the erectile spine beneath
the eye, which acts as deterrent to predators.
Livebearers - Description - This is very brief summary information about the fish.
Everything else is on a separate page. Types: Mollies, Swordtails, Guppies, Platy, Millions Fish
Other Fish - Description - This category comprises: Triggerfish
Did
You Know - Fish Facts: Are
there more mammal, bird or fish species on Earth? Fish! It’s believed there
may be 28,000 different fish species.
What fish can walk on land? The climbing perch. This amazing fish, native to
India, can
walk on land in search of water when its water hole dries up.
The world's largest lake trout was caught on the Saskatchewan
end of Lake Athabasca,
Canada, and
weighed in at 102 pounds.
Global warming
killing marine life
[7 Dec, 2006 2054hrs ISTAP]
WASHINGTON: In a "sneak peak" revealing a grim side effect of
future warmer seas, new Nasa satellite data find that the vital base of the
ocean food web shrinks when the world's seas get hotter.
And that discovery has scientists worried about how much food
marine life will have as global warming progresses. The data show a
significant link between warmer water — either from the El Nino weather
phenomenon or global warming — and reduced production of phytoplankton of
the world's oceans, according to a study in journal Nature.
Phytoplankton are the microscopic plant life that zooplankton and
other marine animals eat, essentially the grain crop of the world's oceans.
Study lead author Michael Behrenfeld, a biological oceanographer at
Oregon State University, said on Wednesday that the recent dramatic drop in
phytoplankton production in much of the world's oceans is a "sneak peak of
how ocean biology" will respond later in the century with global warming.
"Everything else up the food web is going to be impacted, "said
oceanographer Scott Doney of the Woods Hole Oceanographic Institute. He was
not involved in the study.
"What's worrisome is that small changes that happen in the bottom of
the food web can have dramatic changes to certain species at higher spots on
the food chain, "Doney said.
This is yet another study with real-time data showing the
much-predicted harmful effects of global warming are not just coming, but in
some cases are already here and can be tallied scientifically.
10
small steps for a longer life
New Year is a time many of us
resolve to make dramatic health improvements, such as joining the gym and
giving up alcohol for ever (or for at least a month). But some of the most
dramatic changes we can make are incredibly simple.
Here with the help of leading
experts, Good Health offers a guide to the ten easy steps that really will
make a difference to your life: ONE: FLOSS
Flossing at least twice a day is
essential to prevent decay says Dr Nigel Carter, chief executive of the
British Dental Health Foundation.
Too few people floss, putting
themselves at risk of life-threatening diseases such as mouth cancer and
heart disease.
But choose proper dental floss -
according to a recent national dental survey, more than 60 per cent of
Britons use screwdrivers, scissors and earrings to remove food from between
their teeth.
TWO:
HAVE YOUR EYES TESTED:'
A thorough eye test is a health check that can detect underlying conditions
that leave you predisposed to sight loss,' says Ciara Smith, at the Royal
National Institute for the Blind.
'Around 1.9million people with
diabetes aren't having the regular eye tests they need, while 250,000 people
with early-stage glaucoma are at risk of losing their sight but don't
realise it.'
So get your eyes tested at least
every two years.
THREE:
EAT 'GOOD' BACTERIA:
'Good' bacteria - or probiotics - are essential for our digestive health and
helping the immune system to work.
In certain circumstances, for
example prolonged use of antibiotics or a severe bout of vomiting or
diarrhoea, the gut is stripped of its good bacteria. One of the best sources
of probiotics is natural yoghurt.
You can buy other products which
say they include probiotics, although some contain only one of two strains
of good bacteria rather than the hundreds needed. A good health food store
will advise you.
FOUR:
TAKE A CHOLESTEROL TEST:
Coronary heart disease is the
biggest killer in the Western world. In the UK it accounts for one in four
of all male and one in six of all female deaths.
Professor Peter Weissberg,
medical director of the British Heart Foundation (BHF), says everyone over
40 should know their cholesterol level and then aim to reduce it.
'You can't have too low a
cholesterol level,' he adds. 'In the UK we regard 5.5 as an average reading,
although in other countries, such as China, this is considered very high -
and they have a low rate of heart disease compared to us.'
Ask your GP or practice nurse
for a simple blood test. Or you can buy a cholesterol test over the
chemist's counter, but make sure you choose one with separate readings for
good (HDL) and bad (LDL) cholesterol levels: if the results show a high
reading, see your GP.
FIVE:
STOP SLOUCHING:
Better posture is the single most effective weapon against chronic back
problems, says Matt Todman, consultant physiotherapist at the Sports &
Spinal Clinic in Harley Street.
He recommends taking up Pilates
if you are prone to the problem, but simply stopping your slouch habit at
your desk and not lugging around heavy bags can make a huge difference.
SIX:
SWITCH TO UNSALTED BUTTER:
The recommended amount of salt
per day is 6g, but most of us routinely consume around 9g. Cutting your salt
intake by one teaspoon a day can halve your risk of coronary heart disease,
the UK's biggest killer.
Check food labels. Choose those
with low salt or sodium content - 0.25g of salt per 100g of food, or 0.1g
sodium per 100g. Just switching to unsalted butter, for instance, could make
a difference in the long term - or remove the salt cellar from the table.
SEVEN:
EAT A CAN OF SARDINES A
WEEK:
Omega
3 fatty acids in oily fish (such as sardines, tuna and herring) play an
important part in the development of the central nervous system - and in
countering a range of conditions including heart disease and Alzheimer's.
The Food Standards Agency says
we should each try to eat two portions of fish a week, one of them oily.
EIGHT:
REDUCE YOUR WAISTLINE:
A recent study found that people
who had the biggest tummies were 40 per cent more likely to suffer from a
heart attack, and that the waistline was a better indication of health than
your Body Mass Index.
Women should have a waistline of
less than 31.5 inches and men 37 inches. The simplest way is to lose weight
overall, and the BHF recommends aiming for a loss of just 2lb a week over
the long term.
NINE:
SQUEEZE YOUR PELVIC FLOOR MUSCLES
: One in three women in the UK suffers from urinary incontinence - but the
embarrassing nature of the problem means many never see a doctor.
'Urinary incontinence can
disrupt a person's social life and thousands become clinically depressed
because of it,' says Dr Sarah Jarvis, women's health spokesperson for the
Royal College of GPs.
Doing regular pelvic floor
exercises improves bladder control. First, squeeze your pelvic floor muscles
as if you were trying to hold back urine. Then tighten these muscles and
hold for a few seconds. Repeat this ten times, and do the whole exercise at
least four times a day.
If you suffer from incontinence,
ask your GP to refer you to a specialist nurse. For more advice, call 0870
770 3246 or visit www.incontact.org.
TEN:
STOP MAKING PLANS:
'Live in the moment,' says psychotherapist Derek Draper. 'The new year is a
time when people reflect on the past and make plans for the future, but if
you have too many regrets or set yourself unachievable goals, you'll end up
disappointed.'
A review by the U.S. National
Academy of Science showed increased 'mindfulness' - the psychological term
for living in the moment - led to less stress and boosted the immune system.
A review by the US National
Academy of Science shows increased’ mindfulness’, psychological term for
living in the moment, leads to less stress and boosts the immune system