Abundance of marine life in the past

Before the whale hunt in the 1800s, the waters surrounding New Zealand had about 27,000 head whales - about 30 times the current number of whales - according to one of the reports of rebuilding the marine life in the past. Presentations at the Sea Life Conference from May 26-28.

At the same time, British researchers reported that blue and blue whales, blue sharks and threshers thrust off Cornwall, England, the dolphins that sought prey in the upstream. .

Using a variety of sources like diaries, literary writing, compiled legal documents and even keepsakes, Census researchers are focusing on images - some unclear and some are of high resolution - of fish of such size, widely distributed and rich in the past.

They also focused on the time when these giant species of animals declined. For example, Census scientists said the size of freshwater fish in Europe began to diminish in the Middle Ages.

Researchers James Barret and Jen Harland (University of Cambridge, UK), Cluny Johnsone (York University, UK) and Mike Richards (Max Planck Academy, Germany) said the transition from consumption of freshwater fish to Marine fish species began in the 1000s AD.

This is also in line with historical data analyzes from the United Kingdom and Northeastern Europe, suggesting that freshwater fish become smaller, and fewer species at the beginning of the Middle Ages, due to exploitation and umbrellas. Infection increased.

Maria Lucia De Nicolo of the Università di Bologna stated that boats and fishing gear invented in the 1500s made fishing shift from the coast to deeper waters. The revolution of sea fishing began in the mid-1600s when pairs of boats pulled a net.

Assessing modern marine life through a narrow window of observations in recent decades 'distorting awareness', Andy Rosenberg of the University of New Hampshire, project leader History of the marine biology community (HMAP) ) of the Censes, as well as the conference president, said. He judged that new knowledge, gathering information for centuries, changed the notion of size, habitat, abundance of natural marine life, and made the authorities consider boundary of marine life.

In almost every place, man-made changes to the marine ecosystem have been going on for millennia while reliable information is limited only in the last few centuries. However, New Zealand, where about 300 Eastern Pacific Islanders first arrived in 1280 AD, recorded the human impact on the marine environment, including whaling. Bull head, quite short and complete.

These historical documents allow researchers to determine the degree of change in at least one marine ecosystem, from pre-humans to date, and increase the reliability of these findings. with policy makers who will use those results as a realistic boundary for controlling current and future marine ecosystems.

The number of southern whale head whales (Eubalaena australis) in the past has been incorporated into New Zealand coastal ecosystem models to help guide conservation and management.

The HMAP Census team, Jennifer Jackson and Scott Baker (Oregon State University, USA), Emma Carroll and Nathalie Patenaude (Auckland University, New Zealand), and Tim Smith (United States National Marine Life Agency), Estimate the number of whales by analyzing more than 150 logbooks and other records.

They reported that the number of southern bull whales was between 22,000 and 32,000 in the early 1800s, and declined rapidly when whale hunting began. Until 1925, only about 25 reproductive females survived. The remainder today - hopefully recovering - about 1,000 whales, is currently being studied around semi-Antarctic islands south of New Zealand.

Alison MacDiarmid, a New Zealand government scientist, said: 'These findings point to the need to redefine the importance of southern bull whales in the past, as feeding animals. plankton as well as prey for killer whales and white sharks'.

Sea Past Conference II, 2009

International scientists who come to Vancouver participate in the Second Sea Past Conference (May 26-28, hosted by Columbia University), sharing many other surprises:

Fish catch by humans and impacts on near-shore marine life and islands - including the capture of shellfish (clams, shellfish, shrimp, crabs), finned fish and other species Other mammals - beginning in the middle of the Stone Age - 300,000 to 30,000 years ago - 10 times earlier than previously thought.

Paragraphs of Latin and Greek poetry written in the 2nd century CE show that the Romans began fishing with nets.

From the beginning to the middle of the nineteenth century, the years of abusive fishing led to extreme weather and eventually the disappearance of herring. Later, the jellyfish, which was the prey of herring, thrived, seriously altering the food web.

In the mid-1800s, apricot and vegetable nuggets were brought from the UK to Nova Scotia - the beginning of a series of 'invasive' species brought to North America.

In less than 40 years, Philippine seahorses dropped to only 10% . This number is calculated from fishing records, every night 200 seahorses are caught.

The set of images illustrates the decline in size, species diversity and abundance of fish in the Florida Keys for decades.The photo below is taken in 2007. (Photo: HMAP / CoML / Monroe County Library)

New context for marine management

Ian Poiner, president of the Census Science Council, said: 'Joni Mitchell once had a famous song saying' you don't know what you have until it disappears. ' But when it comes to marine life, in many cases we are just beginning to realize what this act once had. '

'The knowledge gained from this study provides a new context for today's marine management efforts. Understanding the complexity of the problem and the changing factors in the past is essential to properly assess today's trends and set a plan for the future. '

Dr. Poiner added that building an environmental history in marine science will be one of the Census's focuses.

Scientists participating in research come from a variety of disciplines including anthropology, archeology, history, ecology.

Use creativity to reveal changes of the sea.

To demonstrate one of the many new research techniques, HMAP Caribbean researcher, Loren McClenachan of Scripps Institution of Oceanography, compared images of 13 groups of 'booty' reef fish to land. by Key West area fishermen from 1956 to 2007.

They revealed that the average size of fish decreased from about 20kg to 2.3 kg and the mix of species also changed significantly.

Between 1956 and 1960, larger groups and other predatory fishes predominantly captured captured species, including sharks with an average length of 2 meters.

In contrast, smaller groups with an average length of 34.4 cm accounted for the majority of species caught in 2007.

Special focus on changing coastal biodiversity

HMAP researchers are also very focused on the history near the Atlantic coasts, assessing changes in coastal biodiversity over time.

To illustrate the cycle of change through looking at the past, the project's scientists rely on data from five countries and implement modern methods of sampling and analysis, examining the hypothesis that diversity Marine biology is more seriously affected than the mainland.

Lessons from past recoveries

Researchers from Dalhousie University of Canada, said: 'Most of the successful sea restoration processes have been found in mammals and birds, but cases include marine reptiles and Fish also exist. However, in only a few cases, they really completely restored their previous richness. '

Lotze points out examples of these revisions - the South American sea otter, the sea elephant of Guadalupe, an island off Baja California, and the Pacific gray whale off the Americas - as well as the raw multiply behind.

She explained: 'In the past, some combination of reduction or ban on exploitation, pollution control and protection of habitats, especially breeding stock and food areas'.

Resilience also depends on the severity of species decline, species life history. Longer-lived marine species often recover more slowly than shorter-lived animals. Species diversity and food networks are also identified as important factors for recovery.

Observe important cycles over time

'Predicting and looking back on the past is two sides of the same coin', Jesse Ausubel, program director of the Censes at the Alfred P. Sloan Foundation, said. 'Analytical tools developed by ecologists to predict the future have been improved to build up the history of marine life'.

'The evidence of HMAP includes many categories such as restaurant menus, maritime diaries and legends and paintings. HMAP researchers try to expand the limits of knowledge by finding obsolete methods. This helps us clearly see useful resources and materials. '

He cited a passage written in Sicily in 1153 describing the North Atlantic seas with 'very large animals, and island residents using their bones and spine instead of wood to build houses. . They used bone to build hammers, names, spears, knives, chairs, stairs and all other things made of wood '.

'The historical project of marine animals has advantages for decades and even centuries in predicting trends - both good and bad. The unification of this information will expand the data system and help find important cycles in larger areas, in longer periods, and include more life forms. '

Professor Poul Hom of Dublin Trinity College concluded: 'The history of the marine life community was a big question, but recent scientific advances and historical methods have allowed HMAP to expand its scope. en what we know '.

'We now know the distribution and diversity of marine life changes rapidly over time. The climate and human impact have made some marine species extinct, and the entire marine ecosystem may have been exhausted to the point of irreversible '.

'Understanding the historical cycles of resource exploitation and recognizing what is lost in the habitat is essential to implementing marine ecological restoration plans.'