The folks at Stillwaters regularly “take the pulse” of Carpenter Creek and its estuary by sampling water quality.  We have also been taking a snapshot of what lives in these waters as well. It has been fun and exciting.

The work is especially important now with construction of the Stillwaters Fish Passage beginning soon. The seining surveys give us an idea of what species use the estuary and we can compare the information to data gathered after the project is completed to help gauge its success.

This May, teams towed large nets called pocket seines through the deeper pools on either side of the culvert under South Kingston Road, near Arness Park, to capture fish and other critters. The animals caught were counted, measure, and released.

The net used is an 80-foot-long rectangular net that is 6 feet deep in the middle and tapers to 3 feet at the ends. It has foam floats along the top edge and lead weights along the bottom. It acts like a moving fence when it’s dragged through the water, herding fish, crabs or other critters in its path. Openings in the mesh are about 1/8th of an inch wide, which lets smaller fish escape and is easier to pull through the waters. Volunteers hold both ends of the net and slowly draw them together to capture the organisms.  Because the pools sampled are deep, we were not able to reach the bottom and some fish were able to swim below our net.

As the net was pulled in, we stood ready to hand dip fish out of the “pocket” of the net into waiting buckets so they could be measured and quickly released. The fish species were separated so as not to put prey (small salmon, surf smelt) in with predators (sculpins or big salmon). We have seen five salmon species (coho, pinks, chum, chinook, and cutthroat).

As we counted the coho, we waved a special wand near their heads to see if they were carrying a coded wire tag put in at hatcheries, or clipped fins. None had indications of a hatchery; they were all wild!  Carpenter Creek is very productive stream for wild coho.  While the number of coho leaving this stream for the ocean is unknown, during 2011 sampling we have seen between 35 and 78 coho on each day.  Their size ranged from 3.5 to 7.9 inches.

It is also important to remember that salmon move out to the saltwater environment based on subtle environmental cues, such as temperature changes or high flows. It is impossible to know how many  coho the Carpenter Creek watershed produces without sampling more frequently.  However, Paul Dorn, fisheries biologist leading the seining effort, indicated that this was a lot of coho from one small stream.

Only two chinook have been present in the four seining events, both were from hatcheries.  Cutthroat were abundant, and one found on May 14 measured 11.34 inches.  In 2010 pink salmon were numerous in our sampling.  Since pink salmon do not spawn in our creek, this is a sign that the estuary is providing habitat for growing salmon from around the sound.

The other fish species were shiner perch, staghorn sculpin, sharpnose sculpin, surf smelt, saddleback gunnels, pipefish, starry flounder, candlefish and sand lance. On May 14, we captured 2,022 shiner perch were captured in one net tow!  Staghorn sculpin were also very abundant (27 to 84 fish). Dungeness crabs, shrimp, and shore crabs were also found.  One Dungeness crab this year had just molted and it shell was just hardening. We have one more seining scheduled this season.  I can’t wait to see what we find.

The results illustrate why the bridge restoration project will be so important.  While the bridge project will change the scour holes, the greater flushing after the project is completed will provide additional nutrients, woody and other organic debris, and rich sediment that provide physical habitat and nutritious food for the fish, birds, mammals, and humans that harvest here.  These fish that are already using our estuary will not be restricted to small scour holes, but will have access to more abundant habitat throughout the estuary.

Betsy Cooper is a marine biologist and volunteer with Stillwaters Environmental Education Center.