Monitoring recent shifts in burrowing shrimp populations in coastal estuaries: are they new phenomena and should a shellfish grower be concerned?

Authors: Dumbauld, Brett; McIntyre, Brooke; LEWIS, NATHANIEL - Oregon State University; RUESINK, JENNIFER - University Of Washington; HULL, WESLEY - University Of Washington

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 8/1/2023
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: Ghost shrimp, Neotrypaea californiensis, are important components of estuarine intertidal communities along the US Pacific coast, but are of significant concern to shellfish growers, especially in Willapa Bay and Gray Harbor, Washington where a program to control these shrimp on shellfish beds was recently suspended. Populations of these shrimp outside cultured areas have been monitored in Willapa Bay, Washington for three decades and in Yaquina Bay, Oregon since 2005. Ghost shrimp density at individual long term monitoring locations established outside of shellfish culture increased dramatically in the 1990s in Willapa Bay, declined almost as precipitously from 2000 through 2010, and has since increased again. Similar though less dramatic population fluctuations have occurred in Yaquina Bay since 2005. These shrimp have pelagic larvae that develop in the adjacent coastal ocean and then “recruit” as postlarvae back to estuaries. Significant relationships between the number of recruits and the number of larger 1 year-old shrimp present have been documented for both of these estuaries, but some precipitous population declines have recently been observed at several locations in Willapa Bay, where larger/older shrimp have either moved/receded or suffered mortality. Results from surveys suggest that shrimp continue to recruit to areas where larger adults have disappeared, but small juveniles are also subject to mortality or move from these areas. It is also now evident that older shrimp move into oyster beds, so it is important to understand the mechanisms that influence post-recruitment shrimp movement and survival due to these shrimps impacts on shellfish aquaculture, but also their broader role and influence on other habitats at the estuarine ecosystem scale.