|
This is a reply from Gary Sharp to Debbie sent to the Fishfolk discussion
list. I thought there was enough interest expressed on Fish-Sci to pass it
on:
*******
I read your posted thesis with great interest. I have concluded that
you need a few courses or if the time is not avilable on your agenda,
to read a few texts. The general thesis that taking fish out of the sea does
not necessaily lead to more fish (that you want) is true.
The reasoning about why is completely off.
Despite the groundfish collapses over George's Bank and off eastern Canada,
the stocks of some less desireable species have not declined, but have
increased.
Off Newfoundland some desirable species have bloomed, as their predators were
removed (lesson #1). I have not stuck my nose into the NE Fisheries Center's
annual assessments recently, but there were lots of Scomber scomber on the
books
over the last decade, that noone wanted.
The declines in biomass of fishes in many locations are cyclical, and indeed
about both the fate of primary production assimilations and temperature. The
example you use is a classic one: smaller fish at age is a symptom of thermally
induced increased
meatbolism, resulting in individual fishes spending more of their consumed
energy on respiration (running the engine faster, as in driving your car around
in 2nd gear), and having less available for somatic growth. (recommended
course:
Physiology 101).
There is another scholl of physiology in which you see enhanced growth, and
either death or smaller age at maturity as a stress symptom. The field is
called
hormesis, and is what makes green houses, stockyards, and hen
houses/eggeries so
productive, and human baby-booms after major Wars...
The consequences of environmental chnages on long-lived fishes is notable, and
has been studied and written about for several decades. My favorite treatise on
systems analysis and where and why the "good times' are misleading can be found
in a wonderfully thorough article penned by Lionel Johnson:The thermodynamic
origin of ecosystems, Can. J. Fish.Aquat.Sci, 38(5):571-590. 1981. A "must
read"
for anyone wishing to understand the consequences of environmental variability
on fish, and their related support systems.
The ultimate question he answered was why all the older fish were in the middle
of the size distributions of arcticc lakes with only one fish species? You have
the answer above, but would not know it, because of your preconceptions...
The fundamental misconception that you have addressed, but missed the very
direct cause and effect links is that Marine ecosystems have only one, stable
and very productive state, that man has perturbed by hauling out his favorite
food fishes. This is the same basis as the myth of MSY and is a ersult of
"equilibrium-based" thinking.
Equilibrium is shunned in nature, simply because it is so "dead-ended".
Thermodynamic laws don't let you get there, until the universe runs down, and
all energy is used up. Don't wait around. That's a ways off....
No doubt, humans have done a number on every aspect of coastal fisheries, by
what they have done in the coastal oceans, as well, and in fact more
importantly
in many cases, upstream. Habitat manipulation, wetlands destruction, mangrove
removals, and industrial polution have been documented long before WWII, which
indeed caused some regional fisheries (e.g., California sardine) to go into
hyperdrive, but they will/did/have recovered, during this period of "decreased
productivity" that is so well documented in the California Current System. In
fact the present range and status of the California sardine is very likely what
it would have looked like, if no over-fishing had taken place at all, and the
fisheries management were effective. That's another story.
In the 17th Century the Thames river became a true "bog" as the towns
industrialized, populated, and dumped their effluents. By 1850 the salmon runs
failed, and fish, seals, and other species simply disappeared. As of the recent
few years, their back! But still mostly near the lower reaches where things are
clearer, and the ocean is nearer.
Conscience, and knowledgeable decisions work.
The major affectors of primary production are indeed light and nutrient levels.
Light is NOT invariant, simply because the water vapor in the atmosphere
(that absorbs the useful wavelengths for photosynthesis) varies over similar
long-term periods as the world's major fisheries.
You can find out more about that by Leonid Klyashtorin and colleagues:
Klyashtorin, L.B. 1997. Global climate cycles and pelagic fish stock
fluctuations in the Pacific. pp20-21 In: Proceedings of Second World Fisheries
Congress, (Hancock, Smith, Grant and Beumer, eds.) CSIRO, Australia.
Klyashtorin, L.B. 1998. Long-term climate change and main commercial fish
production in the Atlantic and Pacific. Fisheries. Res.37:115-125.
People have been asking the right questions for a long while :
Hjort, J. 1914 The fluctuations in the great fisheries of northern Europe
viewed
in the light of biological research. Rapp. P-v. Reun. Cons. int. Explor.
Mer. 20:1-228.
Hjort, J.1926. Fluctuations in the year classes of important food fishes. J.
Cons. Int. Explor. Mer. 1:5-38
Fisheries physiological ecology was brought out of the Dark Ages by the
Canadian
folk following Fred Fry's teachings. Rollie Brett's works would clear the myst
for you.
Fry's student's works fill shelves in some libraries.
John Caddy and I whittled out an FAO Technical Document, No. 283, Ecological
Methods for Fisheries Investigations, back in the mid 1980s, that surveys the
various types of interactions that should be considered in fisheries research
and assessments. It should be on your university liobrary shelves. The document
has a pretty substantial reference section.
Below is just the beginning of another recent bibliography (only the B's) that
will provide you with more recent insights into these very important, but
clearly poorly learned lessons about aquatic system variabilities, i.e., what
to measure, how to interpret, and hence, better understand living ecosystems:
Bakun, A., J. Beyer, D. Pauly, J.G. Pope and G.D. Sharp (1982) Ocean
sciences in
relation to living resources: a report. Canadian Journal of Fisheries and
Aquatic Sciences 39(7):1059-1070.
Baumgartner, T.R., J. Michaelsen, L.G. Thompson, G.T. Shen, A. Soutar, and R.E.
Casey. 1989. The recording of interannual climatic change by high-resolution
natural systems: tree-rings, coral bands, glacial ice layers, and marine
varves.
D. Peterson, ed., pp.1-15 In: Aspects of Climate Variability in the Pacific and
Western Americas, AGU Geophysical Monog. 55.
Baumgartner, T. R., A. Soutar and V.Ferreira-Bartrina. 1992. Reconstruction of
the history of Pacific sardine and northern anchovy populations over the past
two millennia from sediments of the Santa Barbara Basin, California. CalCOFI
Report 33:24-40.
Beamish, R. J. (ed.) 1995. Climate change and northern fish populations.
Special
Publication Canadian Journal of Fisheries and Aquatic Sciencse. 121, 739 pp.
Belvize, H. and K. Erzini. The influence of hydroclimatic factors on the
availability of the sardine (Sardinops pilchardus Walbaum) in the Moroccan
fishery pp. 285-327 In: 'Proceedings of the Expert Consultation to Examine
Changes in Abundance and Species Composition of Neritic Fish Resources'. San
Jose, Costa Rica, April 1983. (G.D. Sharp and J. Csirke, eds.) FAO Fisheries
Report series 291(2).
Boehlert, G.W. and J.D. Schumacher, eds. 1996. Changing Oceans and Changing
Fisheries: Environmental Data for Fisheries Research and Management. NOAA
Technical Memorandum NOAA-TM NMFS-SWFSC-239. 146 p.
Boyle, E.A., and Keigwin, L., 1987. North Atlantic thermo-haline circulation
during the past 20,000 years linked to high latitude surface temperature.
Nature, 330:3540.
Broecker, W.S., 1991. The great ocean conveyor. Oceanography, 4:79-89.
These are empirical works, not modeling muddles, so be aware that there are at
least two cultures in the sciences, empirical observers and those too busy to
look around, the modeling types. There is a third type, and those folks are
empirical model builders. The latter seem to get farther, more quickly, but
also
tend to be very tough to follow, as their models get very busy, very
quickly, as
they learn more about what does what, to what, on which time and space scales.
The families Odum and Idso fit this suit.
ps
Starvation is the way nature cleans out the over-grown predator populations, so
that other things can get moving again. Fishing actually serves that purpose,
perhaps a bit too well, so things really get cropped when both humans and
nature
decide to change the systems at the same time, hence the need for greater care
once nature starts another climatic transition.
I hope that you can take this as information, not criticism.
You have some of the question right, but...
The Right Questions lead to more useful answers.
That is what good science is all about.
Cheers,
Gary D. Sharp
Center for Climate/Ocean Resources Study
PO Box 2223, Monterey, CA 93940
<http://www.monterey.edu/faculty/SharpGary/world>
831-449-9212
[log in to unmask]
"The improver of natural knowledge absolutely refuses
to acknowledge authority, as such. For him, scepticism
is the highest of duties; blind faith the one unpardonable sin."
Thomas H. Huxley
><> ><> ><> ><> ><> ><> ><> ><> ><> ><> ><> ><> ><> ><> ><> ><>
To leave the Fish-Sci list, Send blank message to:
mailto:[log in to unmask]
For information send INFO FISH-SCI to [log in to unmask]
><> ><> ><> ><> ><> ><> ><> ><> ><> ><> ><> ><> ><> ><> ><> ><>
|
