Today we assessed Goose Point seed outplants near Willapa Bay, WA.

Overview

We outplanted oysters at Goose Point last summer (June 2024) after conducting sub-lethal stress hardening treatments. We either exposed oysters to weekly elevated temperature stress or weekly fresh water stress for ~4 weeks prior to outplant. We assessed growth and survival again today.

More information on this project can be found in the GitHub repo and my past notebook posts.

Assessment

The Goose Point crew pulled in all of the cages. All 14 bags were retrieved and were closed. The bags were very fouled with oysters. We moved oysters from these 1 cm cages to new 2 cm cages today.

We then did the following things for each bag:

• Empty the bag onto a table
• Count the number of dead oysters
• Imaged all oysters with a scale bar for growth analysis using ImageJ
• Added a new yellow ID tag
• Moved oysters into a new clean bag with the new tag
• Moved loggers into the new bags

The bags were processed and will be redeployed today or tomorrow. Here are some notes from today:

• Loggers were downloaded, cleaned, and redeployed.
• Oysters are very large! After removing dead shells and moving into new cages they have more room to grow.
• Goose Point observed mortality (up to 50%) in their stocks, and we noticed increased mortality (the most we have seen) today.
• These oysters are in year 2 of outplanting.
• Due to mud and fouling, we had to tap oysters and inspect them closely to find all dead shells.

Here is an example of the size images:

Metadata are on GitHub here. All data and size images are on GitHub here.

Survival

We noticed 10-30% survival in our bags. All bags had approximately 100 oysters. I’ll do a full analysis of the survival data once we complete size and live counts from the image analysis (see Next Steps below).

Here are the preliminary survival results.

This is summarized by control oysters vs oysters that received any treatment (fresh water or temperature). There appears to be higher mortality in previously treated oysters. This is similar to our observations at Westcott.

When viewed by experiment, the same trend appears with higher mortality in treated oysters. Note that the experiments each had their own control group, so that is why there are two control groups and two treated groups.

Temperature

I then plotted temperatures over the entire course of our deployment.

Temperatures have increased over the summer, but are not any warmer or cooler than last year on average.

Next steps

• Return for another assessment in October this year to assess and likely switch out loggers
• Measure size from images as described on GitHub here