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Subject: Re: The Ocean is Starving!
From: John Gilbey <[log in to unmask]>
Reply-To:Scientific forum on fish and fisheries <[log in to unmask]>
Date:Wed, 8 Mar 2000 16:00:33 -0000

text/plain (180 lines)

A few points

> CATCH FISH! ...And it never has been....Annual worldwide fish harvests are
> around 100 million tons - if no-one went fishing next year would the blue-
> green algae respond to this change by putting the brakes on and NOT fixing
> the nitrogen required for 100 million tons of fish? No, the blue-green
> algae are relatively unaffected by fishing and will only do what they have
> always done, that is: produce a SMALL annual gain in protein. "IF" they
> were capable of producing LARGE amounts of protein on an annual basis they
> would have done so a long time ago,
They do have the potential for greater production, remove the fish which
feed on them and there will be more production.
> and the result, over the millions of
> years of the ocean's existence, would have been a sea overloaded with life
> that would have sickened and died as a consequence long ago.
This is rubbish. They would eventually reach environmental saturation and
the numbers would stabilize at the carrying capacity of the ocean, the same
as all other species both in the sea and on the land.

> Life has been slowly accumulating in the sea this way for MILLIONS of
> years. Over the last 500+ years humans have removed what probably amounts
> to half of the original biomass that was there before the fishing industry
> began. We have run up a huge debt with the sea because our relationship
> has
> essentially been "all take and no give."
This sounds like a huge hole has been left which will not be refilled if
fishing continues. You cannot just take a total figure for biomass for the
last X years and say because so much has been removed there is a hole
amounting to Y tonnes. As long as the amount taken is not above the stock
recruitment levels (not always the case unfortunately), there is plenty of
scope for stock replenishment. (i.e. you can sustainably remove biomass
every year and the total standing crop will remain the same year on year).

> Stocks like the northern cod on the Grand Banks of Newfoundland supported
> major fisheries for many years, apparently up to 30% of that cod stock was
> removed repeatedly on an annual basis and for a long time
This is obviously too much, as fisheries scientists pointed out at the time.
Remember, it is not scientists who make the final decisions about TACs it is
politicians, often with large fishing communities in their constituencies.

> STARVATION - the end result of the depleted biomass - why?...and what
> evidence supports this?
> The reduction of the total marine biomass has resulted in marine life now
> being relatively diluted or "watered down" compared to conditions years
> ago. Individual animals today are therefore faced with diluted prey, which
> leads to difficulty in getting enough to eat, which ultimately leads to
> starvation. For many species this now appears to be a critical problem.
> Plankton is also similarly depleted.
I would like to see some references here, this is not my field but it would
seem to me that if you remove too many fish, the plankton will increase
giving more food for the remainder, BUT there may not be enough fish left
for a viable fishery, and so we see a crash. These are two different things

> The most convincing piece of evidence of starvation that I see is a
> widespread decline in "weight-at-age" in fish over the last two decades.
> Nothing except food shortage would cause this in whole populations. It's
> not a case of too many of one species competing for the normal amount of
> food, since the abundance of these fish is rapidly declining along with
> their individual size. Other evidence...
what about selection pressures. If there are size limits on the fish that
can be taken, those who are smaller will have a better chance of escaping
the nets or being returned. Thus giving a selection pressure for smaller
size at age.

> - decline in abundance of virtually all fish stocks, except for a few of
> the smaller ones and some crustaceans which are at a temporary advantage
> because their predators have disappeared first.
> - decline in the average size of fish that are caught, virtually all
> fisheries are no longer catching any "big" ones.
> - fish are maturing at smaller sizes than they did in the past
> - widespread failure of Atlantic and Pacific salmon stocks to return from
> their time at sea
Yet in the last few years the amount caught at sea has dramatically
declined, BUT the stocks returning are still generally down. If only it were
as simple as a single cause for the fall in stocks, we could then do
something about it easily! Talking about Atlantic salmon, NASCO have
produced reduced quotas, NASF pay fisherman not to fish and the price of
salmon has fallen through the floor, added together this has meant a drastic
reduction in fishing effort and amount caught. If your arguments are true,
this should have meant the salmon stocks returning to our rivers would
increase, but, surprise surprise, they still continue to fall on many/most
rivers. Perhaps this means that if you base all your arguments on a single
piece of evidence or causal factor, your conclusions will be wrong. This is
school level science, in the real world there a multitude or interacting
factors all affecting stocks, and it these that fisheries scientists are
trying to understand.

> Temperature changes doubtlessly affect marine organisms, putting some
> species at a relative advantage and others at a disadvantage, so the
> species mix in the system as well as the ranges of species could well
> change with the temperature. But the SUM TOTAL OF LIFE in the ecosystem
> should not be decreasing from the small-scale temperature changes that we
> have seen recently from global warming. It's not logical. The overall
> decline in sea life is simply the end result of centuries of fishing.
Again, more rubbish, if the change happen at the low end of the food chain
this will effect everything 'upstream' of this.
e.g. if El Nino means a drop in nutrients available to algae and plankton
this will limit their production, fish which feed on these will in turn be
limited, as will fish which feed on these fish etc etc. Thus the whole
systems biomass will fall

> FURTHERMORE...since fishing has been dragging down the whole system for
> centuries, plankton levels have also been in decline for that length of
> time. This includes phytoplankton...and the result of the gradual drop in
More rubbish. I have just been down the corridor to speak with the plankton
people here at the marine laboratory in Scotland and they tell me there is
no evidence for this. There may be a fall in calanus numbers but this is
preliminary at the moment and further it is put down to changes in the seas
circulation caused by global warming (unless you are suggesting that changes
in the seas circulation are also due to overfishing?!) I still do not
understand why phytoplankton numbers should fall if you remove the fish,
surly the opposite would be the case?
> phytoplankton has been a gradual increase in atmospheric carbon
> it looks most likely that declining fish stocks may be the
> CAUSE and not the RESULT of global warming...
> (This view is very much against the grain of current thinking but makes
> logical sense, especially considering the time frame of the CO2
> was up significantly before the industrial revolution...and lots of
> fishing
> and whaling had already been done by that time...)
Do you have any idea how much 'food' you would have to introduce to affect
the feeding dynamics of the oceans!!!!!!
> Regardless of what you think about my final conclusion, I am really
> interested in your opinion on the "starving ocean" theory, and would love
> to hear your comments. If you see a flaw in the logic, please tell me; I
> am
> trying to stimulate a serious debate on this topic. I have done a lot of
> research into this theory and have recently made a website on the theme if
> you are interested in taking a look at it - my main "starvation" argument
> is at
A final point, obviously the fate of our fish stocks is of great importance,
BUT lets have some scientific debate on the issues, not green scare stories.
> -----------------------------------------------
> John Gilbey
> FRS Marine Laboratory
> Molecular Genetics
> Victoria Road
> Aberdeen
> Scotland
> AB11 9DB
> Tel: 01224 295303
> Fax: 01224 295511
> E-mail: [log in to unmask]
> -----------------------------------------------
>  '
>    '
>   '  ///
> <*}}}}}}><
>      \  \

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