Tidal River Fisheries Survey

On the water early in the morning for a day of fish survey work in St. Mary’s County, MD

DSC_4706

We are currently performing a multi-day, multi-year fisheries survey.  I now know where the term “a boatload of sh*t” comes from, as we don’t have much room in the boat with all of our equipment.

DSC_4708

Our work is to determine what species utilize these particular tidal stream reaches, at what life stages, and at what times of year.

DSC_4712

As we beach, we are greeted with Virginia Salt Marsh Mallow (Kosteletzkya virginica) in bloom.

DSC_4718

Jessica takes secchi disk turbidity readings and then YSI readings for dissolved oxygen, pH, temperature and salinity.

DSC_4725

Jim then moves on to sediment sampling so that we can ascertain what benthic critters occupy the substrate.

DSC_4728

The sediment sampler is effectively a heavy clam-type bucket loader.  When you drop a weighted hammer device down the rope line, it releases the scooping doors and extracts a substrate soil sample as you pull the sampler out of the water.

DSC_4730

The rinsing process helps us to “pickle” the critters for lab identification.

DSC_4737

We then move on to perform seine net sampling and gill net sampling at multiple locations (and yes, we have the necessary permits).  All fish caught are measured for length, species determined, total number caught and then released back to the water.  The fish in this photo is a menhaden.

DSC_4739

Picking through the gill nets is a laborious task, and unfortunately we cannot save all of the fish extracted, which then becomes crab food (the circle of life).  This photo is of striped bass.

DSC_4743

In descending order of total numbers for today’s research, silversides were the most plentiful, then followed by croaker, white perch, striped bass, menhaden, shad, bluefish and blue crab.  All told, we caught and documented well over 400 fish today, with about 90% being silversides.

DSC_4751

When we combine the previous studies and the results of our multi-day and season studies, the analytics will better reveal recommended approaches for fisheries management.

Note the pale green and gray periwinkle snails, left of Jessica on the vertical stems, which move up and down along the Spartina with the tides, as they feed on detritus that attaches to the stems.

Great day in the field.  Thank you Jim and Jessica.

 

Advertisements