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Intern or volunteer on one of PSI's research projects or outreach campaigns.


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The man with a plan

PSI researcher, Andy Suhrbier helps shellfish growers adapt to changing ocean conditions.


Follow the South Sound Light Trap Team this summer as we search for tiny Dungeness crabs!

Light Trap Monitoring

What is a Light Trap?

Our light trap is featured in the image below. It has a large float on top to keep the trap upright in the water and a weight at the very bottom to keep the large jug (yes that's a 5-gal water jug!) submerged in the water near the surface. Large funnels are attached to the sides of the jug that allow animals to swim in, but not out. At night, the timer inside the trap turns on a strip of led lights, attracting animals to the trap like a moth to your light at night! When we pull the trap out of the water, the sample drains through a filter attached to the bottom of the trap, called the cod end. The cod end helps filter the water out, but collects the tiny crabs we want to see and count!

Light Trap

This style of light trap was designed by marine scientist, Dr. Alan Shanks to study larval Dungeness crab on the outer coast of Oregon and Washington. Biologists from the Swinomish Tribe standardized the design for research purposes throughout Puget Sound. The collaboration of scientists using the light traps belong to the Pacific Northwest Crab Research Group, formed in 2018. Our trap represents the South Sound region, monitoring April - September at Zittel's marina. Photo credit: Debbie Preston

What are we looking for?

We have joined biologists throughout the Puget Sound region to participate in annual, long-term monitoring of juvenile stages of Dungeness crab, including megalopae (below) and instars. Data collected from April - September helps crab fishery biologists make decisions about how adult populations of Dungeness crab should be sustainably managed year to year.


A Dungeness crab in the megalopa stage. Relatively large compared to other crab species, their carapace width ranges from 3.5mm to 4.6mm.

Why is it so important?

Recent declines in adult Dungeness crabs throughout Puget Sound prompted the formation of the Pacific Northwest Crab Research Group (PCRG) in late 2018, led by treaty tribes and supported by state and federal agency biologists, university scientists and non-profit organizations to provide science-based information for adaptive planning and management of this species.

Fishing pressure and impacts of climate change, including low pH are among the drivers implicated in recent recruitment failures and smaller adult populations. Collecting information on the early life stages of the Dungeness crab will help inform and forecast how healthy adult populations are throughout Puget Sound. Monitoring a keystone species, such as the Dungeness crab, gives us a big picture view of how the rest of the ecosystem is doing. Changes in adult populations and fisheries management of this species has broad economic and cultural impacts. Many communities around Puget Sound rely on the Dungeness crab fishery for their livelihood and food security, valued at $12.5M in Washington state.


Light Trap Template

Print your own graph template to follow along from home each week! How many baby crabs did we count? How warm was the water? Draw one of the creatures we found this week! Share your graphs and drawings with us, we'd love to see your results!



Starting July 1st, FOLLOW OUR BIOLOGISTS as we count baby crabs and identify the amazing marine life attracted to our light trap!



Collect your very own Critter Cards! Througout the summer we'll feature new creatures we found in our light trap for you to learn more about. Save the cards in a "digital deck" or print at home! Stay tuned to collect the whole set!


Crab Guide

Zooplankton ID

Invertebrates of the Salish Sea

Kozloff, E. N. 1996. Marine Invertebrates of the Pacific Northwest. University of Washington Press. 552 Pp

Meet the Team:

Margaret Homerding, Shellfish Biologist, Nisqually Tribe

Shannon Boldt, Biologist & Board Member, Nisqually Reach Nature Center

Allison Brownlee, Aquatic Reserves Specialist, WA DNR Aquatic Reserves

Katie Houle, Research Biologist, Pacific Shellfish Institute

QUESTIONS? Contact Us!


Zittel's Marina for hosting the South Sound light trap

Boston Harbor Marina for hosting the PSI light trap

Keta Legacy Foundation

The Russell Family Foundation

Squaxin Island Tribe