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Posts Tagged ‘Aquaculture’

Sciencedaily.com

Despite the growing importance of farmed fish for economies and diets around the world, the origins of aquaculture remain unknown. The Shijing, the oldest surviving collection of ancient Chinese poetry, mentions carp being reared in a pond circa 1140 BC, and historical records describe carp being raised in artificial ponds and paddy fields in East Asia by the first millennium BC. But considering rice paddy fields in China date all the way back to the fifth millennium BC, researchers from Lake Biwa Museum in Kusatu, Japan, the Max Planck Institute for the Science of Human History in Jena, Germany, the Sainsbury Institute for the Study of Japanese Arts and Cultures in Norwich, U.K., and an international team of colleagues set out to discover whether carp aquaculture in China was practiced earlier than previously thought.

Carp farming goes way back in Early Neolithic Jiahu

Jiahu, located in Henan, China, is known for the early domestication of rice and pigs, as well the early development of fermented beverages, bone flutes, and possibly writing. This history of early development, combined with archaeological findings suggesting the presence of large expanses of water, made Jiahu an ideal location for the present study.

Researchers measured 588 pharyngeal carp teeth extracted from fish remains in Jiahu corresponding with three separate Neolithic periods, and compared the body-length distributions with findings from other sites and a modern sample of carp raised in Matsukawa Village, Japan. While the remains from the first two periods revealed unimodal patterns of body-length distribution peaking at or near carp maturity, the remains of Period III (6200-5700 BC) displayed bimodal distribution, with one peak at 350-400 mm corresponding with sexual maturity, and another at 150-200 mm.

This bimodal distribution identified by researchers was similar to that documented at the Iron Age Asahi site in Japan (circa 400 BC — AD 100), and is indicative of a managed system of carp aquaculture that until now was unidentified in Neolithic China. “In such fisheries,” the study notes, “a large number of cyprinids were caught during the spawning season and processed as preserved food. At the same time, some carp were kept alive and released into confined, human regulated waters where they spawned naturally and their offspring grew by feeding on available resources. In autumn, water was drained from the ponds and the fish harvested, with body-length distributions showing two peaks due to the presence of both immature and mature individuals.”

Species-composition ratios support findings, indicate cultural preferences

The size of the fish wasn’t the only piece of evidence researchers found supporting carp management at Jiahu. In East Asian lakes and rivers, crucian carp are typically more abundant than common carp, but common carp comprised roughly 75% of cyprinid remains found at Jiahu. This high proportion of less-prevalent fish indicates a cultural preference for common carp and the presence of aquaculture sophisticated enough to provide it.

Based on the analysis of carp remains from Jiahu and data from previous studies, researchers hypothesize three stages of aquaculture development in prehistoric East Asia. In Stage 1, humans fished the marshy areas where carp gather during spawning season. In Stage 2, these marshy ecotones were managed by digging channels and controlling water levels and circulation so the carp could spawn and the juveniles later harvested. Stage 3 involved constant human management, including using spawning beds to control reproduction and fish ponds or paddy fields to manage adolescents.

Although rice paddy fields have not yet been identified at Jiahu, the evolution of carp aquaculture with wet rice agriculture seems to be connected, and the coevolution of the two is an important topic for future research.

Materials provided by Max Planck Institute for the Science of Human History. Note: Content may be edited for style and length.

 

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Cosmosmagazine.com

Research points to traditional custodians for clues to sustainable practices. Natalie Parletta reports.

Researchers in British Columbia, Canada excavate ancient shells from the beach of a “clam garden” — a constructed rock-face terrace where Indigenous People cultivated clams.

Mark Wunsch (Greencoast Media, British Columbia, Canada).

Coastal ecosystems are not only threatened by habitat loss and climate change; a breakdown of traditional aquaculture practices could also have contributed significantly to their deterioration.

This has been illustrated by an 11,500-year analysis of human coexistence with clams in British Columbia, Canada, published in the Proceedings of theNational Academy of Sciences.

Ginevra Toniello, from Simon Fraser University, Canada, and colleagues gathered paleoecological, archaeological and modern records of butter clams(Saxidomus gigantea) in the northern Salish Sea to understand their relationship with humans throughout the Holocene.

The cultural significance of these bivalves is revealed by stories, rituals, language and the deep piles of ancient shell middens that line kilometres of coastlines. Archaeological and ethnographic analyses suggest clams were popular food sources harvested seasonally and all year round and enjoyed both fresh and preserved.

Butter clams from 11,500-11,000 years ago (left) and 10,900-9,500 years ago (right) showing the sometimes dramatic differences in size through time.

Archaeological records can also provide insights into the ecological impacts of interactions between humans and fauna, while palaeoecological information can reveal the ecology of species without human interference.

“Taken together,” Toniello and coauthors write, “these two records can offer a powerful lens through which to assess coupled social-ecological systems over broad spatial and temporal scales and can help establish ecological baselines for modern management.”

To peek into the past, the researchers gathered clam shells from middens at five coastal sites and measured the size and width of growth rings in the mollusc’s shells. They put these into context according to their historical location, before, during and after evidence of management by indigenous people and were able to group the samples into seven time periods.

Together, these data allowed them to analyse predictors of clam size throughout the Holocene.

They found the mollusc shells’ size and growth was limited in early postglacial times, but then flourished over the next few millennia until the early-Late Holocene, likely reflecting more favourable habitat conditions.

Middens showed evidence that humans then harvested them around 9000 years ago, and about 5500 years later started constructing clam gardens – “intertidal rock-walled terraces” – as a form of aquaculture management.

The gardens made the bivalves more accessible to harvesters by reducing the beach slope, exposing more beach during low tide, and bringing them closer to human settlements.

The researchers believe the gardens’ construction reflected population growth and increased complexity of social structures, necessitating measures to preserve the clams for food and trade.

By around 2700 years ago, harvesting intensified, yet evidence suggests the clam populations flourished throughout the Late Holocene.

The clam habitats were likely preserved by the gardens built by generations of Indigenous peoples, the team suggests. Along with cultivation methods such as tilling, removing non-human predators, removing rocks, modifying the substrate and monitoring access, the Indigenous people were able to maintain a sustainable harvest.

Toniello and colleagues speculate that the course sediment garden terrace and rock wall also facilitated abundant growth and access to other marine foods like crabs, sea cucumbers and seaweeds.

Sadly, modern records indicate that growing conditions declined since European settlement replaced traditional management practices with industrial activities, with an impact comparable to the ice age.

“It is striking that the growth patterns of clams living in the beach today are most similar to the clams that lived and died in the unstable and relatively unproductive habitats of the Early Holocene,” the group writes.

“As in the Early Historic Period, we propose that the current low productivity is due to the decline in traditional management, including ongoing tilling through harvesting.”

They note it could also be attributed to deposition of fine silts on the clam beaches – less favourable for clam growth than the coarse grains used as garden substrates – as a result of logging, along with warmer ocean temperatures and associated declines in productivity.

Nonetheless, they suggest modern humans could learn much from traditional practices for aquaculture management, which also has broader ecological and ethical implications.

“Examining the deep and specific history of human-species relationships, such as that between people and clams, is requisite for understanding and better managing our resources and ecosystems today,” they write.

“Documenting these interactions between humans and coastal ecosystems, such as we have done here, also counteracts the erasure of the long-term connections of Indigenous peoples to their lands and seas.”

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