Ancient abundance, distribution, and size of Olympia Oysters (Ostrea lurida) in the Salish Sea: a perspective from the Lekwungen village of Kosapsom (DcRu-4), southern Vancouver Island, British Columbia
Date
2024
Authors
Vollman, Taylor
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Abstract
Olympia oysters (Ostrea lurida) are the only oyster species native to the Northwest Coast of North America and are currently a focus of restoration and management following a collapse over the past 150 years. This thesis examines 42 archaeological assemblages containing Olympia oysters in the Salish Sea to better understand Indigenous uses, changes in abundance and distribution between ancient and modern and develops a method to estimate ancient size-at-harvest from partial valves. I observe that Olympia oysters are not a particularly abundant species in archaeological sites when measured by weight and MNI (<15% relative frequency) except in a few sites with high abundance in specific nearshore habitats and locations. Additionally, I examine the size and abundance of Olympia oysters from the Kosapsom Village site (DcRu-4), a site with exceptionally high Olympia oyster frequency (~68 % MNI) located on Southern Vancouver Island in British Columbia in the traditional territories of Esquimalt and Songhees Nations. I compare oyster size ranges from Kosapsom to modern restoration sites and observe that sizes are larger than modern oysters in the same waterway but are similar to a 20+ year restoration site in Fidalgo Bay, Washington. Both abundance and size at Kosapsom increased over 1800 years. I interpret these increased sizes (~14% increase) as reflective of harvesting restrictions and population enhancement strategies, which are consistent with maintaining long-term harvest stability. This research contributes to the growing recognition that archaeological records of traditional Indigenous shellfish use and management hold great potential to expand historical baselines and inform modern coastal restoration and conservation strategies.
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Keywords
Zooarchaeology, Salish Sea, Bivalves, Indigenous Resource Management, Historical Ecology