Posted by: cassandrabrooks | October 22, 2009

Visit to Tomales Bay Wetland

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Tomales Bay wetland, Point Reyes National Seashore (photo credit: Mason Cummings/PRNSA)

It’s another gorgeous fall morning at Point Reyes National Seashore and a perfect day to be out monitoring one of the many lush wetlands in Tomales Bay.

Donned in waders and weighed down with buckets and fish seining nets, we tromp through the thick marshland vegetation doing our best to avoid getting sucked into the many mud puddles.  The tide has receded enough for us to cross Fish Hatchery Creek and to continue trekking across the marsh, which would be buried under a foot or so of tidal water during high tide.

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Seining for fish (photo credit: Mason Cummings/PRNSA)

Our first site is a small flooded pool, which serves as a refuge to fishes and other marine creatures when the tide recedes.  We monitor the pool by taking water quality measurements, including temperature, salinity, dissolved oxygen and conductivity, all of which serve as indicators of how healthy the pool is.

We then dip a fish seine net into the little pool to see what fishes occupy this refuge.  Little sticklebacks and Arrow gobies, not more than one to two inches, flop in the net. We quickly measure and jot down the size of each fish before returning them to their home.

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Tomales Bay wetland water quality and fish seine sampling (photo credit: Mason Cummings/PRNSA)

We move on towards Lagunitas Creek, slowly trudging through the mud.  With each step the air fills with sucking and slurping noises as the mud tries to wrestle our boots from us.  We make it to the edge of the creek, boots caked in mud but still attached to our feet and clamber down the slippery bank to do another water quality assessment and fish seining.  Here we find very little but a Bay pipefish among the eelgrass.

The landscape is gorgeous today, with the vast wetland stretching out in all directions under a clear blue sky.

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The field team sorts fish from the net (photo credit: Mason Cummings/PRNSA)

Wetlands are among the most productive ecosystems on earth and provide food, shelter and nesting areas for a wide array of bird and fish species.  Many juvenile fish find a safe have here, before making their way out to the open ocean.

Because of their high productivity, however, many wetlands here in the Point Reyes region were converted into farmland.  Developers built levies and dykes to obstruct the water flow and created ripe agricultural land, primarily cattle farms.  As resource managers learn more about the importance of wetlands in maintaining regional biodiversity, some are being restored.

One year ago this weekend (Oct 25 and 26, 2009), the Giacomini Dairy Ranch here in Point Reyes had its levies knocked down and has since been gradually returning to marshland.  The new Giacomini wetland has restored roughly 560 acres, which amounts for more than 50 percent of the original Tomales Bay wetlands. Many birds and other animal species have now returned.

Today we are assessing a specific region of the Tomales Bay wetlands that has never been stopped up with levies or dikes.  It will serve as a comparison for the Giacomini wetland, so we can monitor its restoration progress.  Among the species we hope will return are the endangered tidewater gobies, Steelhead trout and Coho salmon, none of which we have found in our sampling today.

We move on to another small pool, where we pull up more sticklebacks, arrow gobies and Plainfin midshipmans.

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Seining for fish in Fish Hatchery Creek (photo credit: Mason Cummings/PRNSA)

The tidewaters are flushing back in, quickly filling and covering the marshland.  We wade across Fish Hatchery Creek, stopping to make one last water quality and fish assessment.  As we drag the net through the creek, the cold water presses the waders tight against my legs and chest.  I pull my suspenders as high as possible to keep the rising waters from spilling over the rim of my waders.

We pull in the net and find a small school of topsmelt, their long silvery bodies shimmering in the sunlight. Among the larger topsmelt are a few more sticklebacks and Arrow gobies, but none of the endangered gobies or salmon.  We didn’t expect to find any of the endangered fish, as they are so infrequently found in the regional surveys.  But hopefully with the newly restored wetlands, these endangered fish will begin their recovery.

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Measuring the length of a top smelt (photo credit: Mason Cummings/PRNSA)

For more information on the anniversary event this weekend, visit

For more information on Giacomini Wetlands Restoration Project, visit


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