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Monday, May 25, 2009

More on Ancient Fishing

On May 24, 5:11 pm, Jack Linthicum
wrote:

I have a book (Tales of Old Florida) which describes fishing trips in
the 1890s where tarpon 6 feet long and 100 pounds weight are taken in
numbers and 150 pounders in 1903.Twenty-pound snapper out of Pensacola
in 1904 to the point the fisherman for fun got tired of the action.
Real commercial fishermen kept hauling.


Ocean life in olden days: Researchers upend modern notions of
'natural' animal sizes, abundance


Census of Marine Life historians reconstruct images of past sea life
that boggle today's imagination


IMAGE: This Byzantine image from the 11th century shows night fishing
with a lamp and a net.


Before oil hunters in the early 1800s harpooned whales by the score,
the ocean around New Zealand teemed with about 27,000 southern right
whales - roughly 30 times as many as today - according to one of
several astonishing reconstructions of ocean life in olden days to be
presented at a Census of Marine Life conference May 26-28.


At about the same time, UK researchers say large pods of blue whales
and orcas, blue sharks and thresher sharks darkened the waters off
Cornwall, England, herds of harbour porpoise pursued fish upriver, and
dolphins regularly played in waters inshore.


Using such diverse sources as old ship logs, literary texts, tax
accounts, newly translated legal documents and even mounted trophies,
Census researchers are piecing together images - some flickering,
others in high definition - of fish of such sizes, abundance and
distribution in ages past that they stagger modern imaginations.


They are also documenting the timelines over which those giant marine
life populations declined.


For example, Census scientists say the size of freshwater fish caught
by Europeans started shrinking in medieval times.


Researchers James Barrett and Jen Harland (Cambridge University, UK),
Cluny Johnstone (York University, UK) and Mike Richards (Max Planck
Institute, Germany) say a shift from eating locally-caught freshwater
to marine fish species occurred around 1000 AD.


That's consistent with analyses of scientifically-dated fish remains
and historical data from England and northwestern Europe showing
smaller freshwater fish and fewer species availability in early
medieval times, likely caused by increased exploitation and pollution.


Maria Lucia De Nicolò of the Università di Bologna, meanwhile, has
established that new fishing boats and equipment invented in the 1500s
made it possible to venture from coastal to deep sea fishing. The real
revolution in marine fishing, she says, happened in the mid-1600s when
pairs of boats began dragging a net.


IMAGE: This composite photo illustrats the decline in size, species
diversity and abundance of gamefish in the Florida Keys.


Appraising modern marine life through the narrow window of
observations during recent decades "skews perceptions," says Andy
Rosenberg of the University of New Hampshire, a leader of the Census'
History of Marine Animal Population (HMAP) project and chair of the
conference.


He says new insights allowed by centuries of information are upending
modern notions of "natural" marine life sizes, abundance, habitats and
vulnerability, and causing authorities to revisit marine baselines.


In most places human-caused changes to marine ecosystems occurred over
millennia while reliable information is often available for just the
last few centuries at best. In New Zealand, however, which was first
settled by fewer than 300 eastern Pacific islanders around 1280 AD,
there is a comparatively short and continuous record of human impacts
on the marine environment, including whaling for southern right
whales.


This short and well-documented history allows researchers to quantify
the full scope of change in at least this one marine ecosystem, from
before human presence to the present day, and makes the findings more
relevant to policy makers, who plan to use the results as a realistic
baseline against which the current and future status of the marine
ecosystem can be gauged.


The estimated historic size of New Zealand's southern right whale
(Eubalaena australis, www.eol.org/pages/313009) population, for
example, is already being incorporated into models of the New Zealand
coastal ecosystem to help guide conservation and management.


The Census HMAP team, Jennifer Jackson and Scott Baker (Oregon State
University, US), Emma Carroll and Nathalie Patenaude (University of
Auckland, New Zealand), and Tim Smith (US National Marine Fisheries
Service), estimated the original population through analysis of over
150 whaling logbooks and other records.


And they say with 95% statistical confidence that southern right
whales numbered between 22,000 and 32,000 in the early 1800s,
declining rapidly once whaling began. By 1925, perhaps as few as 25
reproductive females survived. Today a remnant -- and hopefully
recovering - of 1,000 animals is being studied around sub-Antarctic
islands south of New Zealand.


Says Alison MacDiarmid, a New Zealand government scientist who
organized the work: "These findings point up the need to re-examine
the role southern right whales once played both as a grazer of
zooplankton and prey, especially during calving close inshore, for
killer whales and great white sharks."


Oceans Past II Conference, 2009


International scientists arriving in Vancouver for the second Oceans
Past conference (www.hmapcoml.org/oceanspast, May 26-28, hosted by the
University of British Columbia), will share such other surprises as
these:


* Human fishing and impacts on near-shore and island marine life -
including the catching of shellfish, finfish and other marine mammals
- apparently began in many parts in the Middle Stone Age - 300,000 to
30,000 years ago - 10 times earlier than previously believed;
* Passages of Latin and Greek verse written in 2nd century CE
suggest Romans began trawling with nets;
* In the early to mid 1800s, years of overfishing followed by
extreme weather collapsed a European herring fishery. Then, the
jellyfish that herring had preyed upon flourished, seriously altering
the food web;
* In the mid 1800s, periwinkle snails and rockweed migrated from
England to Nova Scotia on the rocks ships carried as ballast - the tip
of an "invasion iceberg" of species brought to North America;
* In less than 40 years, Philippine seahorses plunged to just 10%
of their original abundance, reckoned in part through fishers' reports
of each having caught up to 200 in a night in the early days of that
fishery.


A new context for contemporary ocean management


Says Ian Poiner, Chair of the Census Scientific Steering Committee:
"Joni Mitchell once famously sang that 'you don't know what you've got
'til it's gone.' But when it comes to marine life, in many cases we're
only just starting to fully realize what the planet once had."


IMAGE: This reproduction from an 1887 paper by A. Howard Clark shows
the processing of a right whale carcass.
Click here for more information.


"The insights emerging from this research of the past provide a new
context for contemporary ocean management. Understanding the magnitude
and drivers of change long ago is essential to accurately interpret
today's trends and to make future projections."


Dr. Poiner adds that establishing environmental history in mainstream
marine science will be one of the Census' enduring legacies.


Scientists involved in the research hail from many disciplines,
including palaeontology, archaeology, history, fisheries and ecology.


Using creativity to reveal marine change


Demonstrating one of many novel research techniques, HMAP Caribbean
researcher Loren McClenachan of the Scripps Institution of
Oceanography, compared photos of 13 groups of "trophy" reef fish
landed by Key West-area sport fishermen between 1956 and 2007.


They revealed that average fish size shrank from an estimated 20 kg to
2.3 kg and that the mix of species changed greatly.


From 1956 to 1960, large groupers and other large predatory fish
dominated the catches, including sharks that averaged nearly two
meters long.


By contrast, small snappers with an average length of 34.4 cm
dominated catches in 2007.


A special focus on changing coastal biodiversity


HMAP researchers are also looking closely into the history near
Atlantic shores, assessing changes in coastal biodiversity over time.


To illuminate patterns of change by seeing what used to be, project
scientists are subjecting rich historical data from five countries to
modern sampling and analysis methods, testing the hypothesis that
biodiversity has suffered more at sea than on land.


Lessons also from past recoveries


"Most histories of successful marine recoveries are found among
mammals and birds, but cases involving marine reptiles and fish also
exist. Only in a few cases, however, did they fully recover their
former abundance," says researcher Heike Lotze of Canada's Dalhousie
University.


Lotze points to hopeful examples of recoveries - sea otters of western
North America, elephant seals of Guadalupe, an island off the coast of
Baja California, and the Pacific gray whales that roam the American
coast, for example - and the causes behind them.


"In the past, some combination of reduced or banned exploitation,
pollution controls or habitat protection, especially of breeding
colonies and feeding grounds, propelled recovery" she says.


Recovery potential can depend on the magnitude of depletion, the life
history of the animals, and the time since collapse. Long-lived marine
animals rebound more slowly than short-lived species. Species
diversity and food webs have also been identified as important drivers
for recovery. And where species have disappeared, their reintroduction
by humans can help, says Lotze.


Seeing important patterns over time


"Forecasting and backcasting are two sides of the same coin," says
Jesse Ausubel, Program Director of the Census at the Alfred P. Sloan
Foundation. "Analytic tools developed by ecologists to predict future
abundance have been adapted to reconstruct histories of marine life."


"HMAP's evidence includes a variety of items such as old restaurant
menus, whalebone buttons, logbooks and lore, paintings and pavements,
isotopes and ice. HMAP researchers keep extending the limits of
knowledge by finding new ways to make the past visible. They help us
to lift self-imposed blinders on what constitutes useful source
material," he adds.


He notes a text written in Sicily in 1153 describing the seas of the
North Atlantic as having "animals of such great size that the
inhabitants of the islands use their bones and vertebrae in place of
wood to build houses. They make hammers, arrows, spears, knives,
seats, steps, and in general every sort of thing elsewhere made of
wood."


"The History of Marine Animal Populations project gives a head start
of decades and even centuries in anticipating trends - both good and
bad. Integration of this information will extend databases to help
perceive important patterns over larger areas, longer eras and
covering more forms of life more reliably."


Concludes Poul Holm, Professor at Trinity College Dublin and global
chair of the HMAP project: "While the history of marine animal
populations has been one of the great unknowns, recent advances in
scientific and historical methodology have enabled HMAP to expand the
realm of the known and the knowable."


"We now know that the distribution and abundance of marine animal
populations change dramatically over time. Climate and humanity forces
changes and while few marine species have gone extinct, entire marine
ecosystems may have been depleted beyond recovery. Understanding
historical patterns of resource exploitation and identifying what has
actually been lost in the habitat is essential to develop and
implement recovery plans for depleted marine ecosystems."


###


Vancouver conference themes include:


* Historical patterns of change in marine ecosystems;
* The social and economic drivers and consequences of the changes;
* Historical examples of ecosystem recoveries and prospects for
future recoveries; and
* The Sea Ahead: the Future of Marine Ecosystems (sponsored by the
Peter Wall Institute for Advanced Studies, University of British
Columbia).


Census of Marine Life


Started in the year 2000, the Census of Marine Life is an
international science research program uniting thousands of
researchers worldwide with the goal of assessing and explaining the
diversity, distribution and abundance of marine life. It is supported
by private sources and government agencies the world over, listed
online at www.coml.org/support.


The Census of Marine Life 2010: A Decade of Discovery, to be released
in London in October 2010, will address three questions:


* What lived in the ocean?
* What lives in the ocean?
* What will live in the ocean?


The Census' History of Marine Animal Populations project was created
to address these questions:


* How have marine animal diversity, distribution, and abundance
changed in the last 2,000 years?
* Which factors forced or influenced those changes?
* What has been the significance of those changes to humans and
the environment? and
* By what processes have marine ecosystems interacted with human
societies?


Since the project began, some 205 books and papers have been
published. And the HMAP database (www.hull.ac.uk/hmap) today holds
approximately 350,000 records, with a goal of 1,000,000 records by the
end of 2010.


The preservation of data will be ensured through the creation of a
World Repository for Marine Environmental History Data.


In 2010, HMAP will publish a general environmental history of marine
animal populations, an image gallery, a series of maps of historical
exploitations and impacts, and papers that synthesize information on
historical declines and recoveries.


Of particular note, the World Whaling HMAP project is in the process
of creating colorful, large-format world maps showing the distribution
of 19th century whaling ships and their prey, providing simple, high-
impact visual representations of the times and places of whaling in
that era. Based on records of 70,000 whale encounters over 450,000
days at sea, the maps invite comparisons of past and current whale
distribution patterns, allowing resource managers to identify where
populations have and have not recovered.


HMAP Sponsors


The History of Marine Animal Populations project receives funding from
sources around the world.


Contributors to research specified in this release include:


* The Danish Council for Independent Research, Humanities
Division;
* Leverhulme Trust;
* Lenfest Ocean Program;
* Alfred P. Sloan Foundation;
* National Institute of Water & Atmospheric Research Ltd.;
* New Zealand Biodiversity Fund administered by the New Zealand
Ministry of Fisheries; US Environmental Protection Agency STAR
Fellowship Program, and
* The Future of Marine Animal Populations, a fellow Census of
Marine Life project.


Many divisions of the National Oceanic and Atmospheric Administration
provided support, including:


* The Office of Ocean Exploration;
* Northeast Fisheries Science Center;
* NOAA Preserve America Initiative;
* Marine Sanctuaries Program;
* Reef Conservation Program;
* National Centers for Coastal Ocean Science;
* National Marine Fisheries Service; and
* OAR Cooperative Institute.
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2 comments:

John said...

Well, you might think that fish that live in the deepest of the waters have more oil and hence, are more suitable for deep sea fish oil production. However, the truth is just the opposite. Researches show that fish that live in the middle waters or near the surface are oilier than those who live in the deepest part of the ocean. Due to the growing water pollution and commercial fishing methods, some species of the fish are becoming extinct day by day. Studies show deep sea fish tend to live around 60-70 years whereas fish that live near the surface enjoy a shorter lifespan. Due to their short lifespan, they do not accumulate harmful contaminants make themselves ideal for deep sea fish oil products. Deep sea fish have higher Omega3 content and are perfect for EPA fish oil products.

John said...

Well, you might think that fish that live in the deepest of the waters have more oil and hence, are more suitable for deep sea fish oil production. However, the truth is just the opposite. Researches show that fish that live in the middle waters or near the surface are oilier than those who live in the deepest part of the ocean. Due to the growing water pollution and commercial fishing methods, some species of the fish are becoming extinct day by day. Studies show deep sea fish tend to live around 60-70 years whereas fish that live near the surface enjoy a shorter lifespan. Due to their short lifespan, they do not accumulate harmful contaminants make themselves ideal for deep sea fish oil products. Deep sea fish have higher Omega3 content and are perfect for EPA fish oil products.