In  recent fishing reports and seminars I’ve focused on the importance of thermal layers and salt water stratification in identifying good places to fish.  One of the reasons I enjoy fishing around the Chesapeake Bay Bridge is because there are constantly swirling currents where seawater from the ocean mixes with the freshwater from the rivers. Scientists refer to areas where salt and freshwater mix as the Estuarine Turbidity Maximum or ETM.  While most Chesapeake Bay researchers put the area of greatest turbidity north of Swan Point, there’s no denying that the water under the Bay Bridge is in a constant state of flux. This creates specific habitat zones which vary depending on the weather, currents, and tides.  The challenge for fishermen is to concentrate on the areas where fish are most comfortable because that’s where they are more likely to feed.  Once we find the depth, we can optimize our lure selection and modify our presentation so that our chances for hooking up are best.  Most of us haven’t heard very much about ETMs, salinity stratification or thermal optimums because we use another term when we talk about those layers.  Fishermen call it the Strike Zone.  John Page Williams and I decided to sneak in a two-hour pre-work jigging trip this morning in search of the Strike Zone

We trailered John Page’s 17′ Boston Whaler Montaulk First Light to Sandy Point State Park where we launched about 6:30 AM.  Our first order of business was to compare notes on our favorite pilings.  Since it turned out we liked to fish the same ones, we got right down to work.   I really enjoy fishing the bridge in small boats.  It allows access to tight places that would otherwise be impossible to fish.  John Page positioned the Whaler perfectly on the down-current pressure side of the pilings while I stood on the bow platform and slung a jig.   With overcast skies, a new moon, and the north wind against a waning out-going current, everything seemed perfect for a fantastic morning of piling picking.  There was only one problem:  someone forgot to tell the fish.  They weren’t there.  We worked from west to east eventually losing what little current we had left, but there were no stripers anywhere to be found.

With only 90 minutes left to fish, we considered a run to an underwater ledge where I’ve found good post-spawn fishing in the past.  In fact, I caught a few fish there just last weekend.  No one would ever find this area if they didn’t know it was there, just a little hump in the middle of nowhere that happens to hold big rockfish when they come off the spawning grounds. I read the grid coordinates off my cell phone to John Page while he punched them into his Lowrance HDS-8 GPS/Fish Finder combo and calculated our time.  “Twenty minute run,” he announced.  I thought it might be our best chance at avoiding a skunk.

“Let’s go!”

Last weekend I noticed on the sonar that the fish were holding very close to to the twenty-two foot mark, so that would be our target.  We arrived at our destination and eased over the ledge at what we thought would be the optimal depth.  Unfortunately, the only returns on the fish-finder were reflections of the hard bottom.  No fish.  We stared at the blank screen as we worked our way down the gradual ledge.  Just about the time we reached twenty-four feet, some marks appeared. There was not a lot of fish, just a few along with some small pods of bait.  What we found more interesting were two very clear horizontal lines that appeared on the screen.   One at sixteen feet and another at twenty-four.  The fish were holding tightly to the deeper line. In freshwater I’d call those lines thermoclines, but things are different in the Bay.  I winged a guess at what we were looking at, but John Page decided to take a more scientific approach.

In his work as Senior Naturalist for the Chesapeake Bay Foundation,  John Page spends a lot of time looking at water quality.  He had an instrument on-board First Light which could test salinity, water temperature, dissolved oxygen and other parameters.  I manned the wheel as he dropped over a weighted probe and scanned the screen for results.  I had never seen this kind of testing before, and found it fascinating. After checking each value in roughly two meter increments and writing the results down in his journal, he compared them to what we were seeing on the fish-finder.  The results were immediately apparent. Here are a series of photos that show what I mean.  I added the red lines on John Page’s journal to show where the major changes occurred.   A quick conversion of meters to feet reveals the most obvious drops in salinity and dissolved oxygen occur almost exactly where we were seeing the horizontal lines on the sonar.  We were looking at three distinct zones of salt water, each floating on top of the other.  The salinity figures from the tester matched the lines on the screen. They were as clear as layers in a cake.

That information by itself was probably worth the trip.  I’d always suspected salinity stratification was triggering the bite in this area, but it was fascinating to see the proof.  Still, no matter how smart we felt, one fact remained – this was a fishing trip and we were skunked.  Since the fish were obviously holding where the twenty-four foot salinity line intersected the ledge, we positioned the boat so we would drift over it.  By now we had outgoing current with a ten knot north wind so we were drifting quickly and needed one ounce jig heads to feel the bottom.  With only fifteen minutes left to fish, we killed the engine, faced the wind and started casting. Just about the time we hit the magic number of twenty-four feet, John Page called out,  “Got him.”

I looked up to see some nice rod dips and grabbed my camera as I heard his drag start to scream.  After some quick action shots I untied the Frabill cradle net that was secured to the Whaler’s bow rail.  After a short but fierce fight, John Page deftly swam the fish head-first into the net then reached down and removed the chartreuse Gulp shad and candy corn jig head. The wide twenty-nine inch rockfish never left the water. All it took was a slight opening and lowering of the net, and the fish gave a mighty tail-slap and swam away.  We couldn’t have scripted it any better.    It was a nice fish at the right time and just where we hoped it would be, exactly in the strike zone.

After another drift our time was gone. I looked again at the statistics John Page had written down and noticed that the dissolved oxygen was much lower at depths over thirty feet.  When I asked why, he told me that dead zones were starting early in the year in this part of the Bay.  Bacteria is growing fast and eating up the oxygen.  He explained that rockfish prefer dissolved oxygen levels of 4 – 5 and can’t tolerate levels below 3.  The optimum range for juvenile stripers is  6-12. The more I think about that the more concerned I get.   The fish were holding in a very narrow band at twenty four feet because that’s where they were most comfortable.  They didn’t want to swim up because of the salinity, and they couldn’t go deeper due to the lack of oxygen.  It squeezed them into a narrow strip, maybe two foot wide by six foot high in which to eat. That’s the only place we could reasonably expect to catch stripers at this location.   It’s not enough.  No wonder fishing is so tough.

Even if I didn’t know already, the information gained in this fishing trip is enough to convince me that we have to do something quickly about the water quality in the Chesapeake Bay.  You may have heard that The Chesapeake Bay Foundation just settled their lawsuit with the Environmental Protection Agency (EPA).  The binding settlement calls for specific actions that would  have a positive impact on the health of the Bay.  But in a conversation with EPA Associate Administrator Chuck Fox yesterday, I learned that there may not be enough teeth in existing laws to force individual states to comply with the settlement.  Fishermen can change that.  The Chesapeake Clean Water Act that is pending before Congress would force states to clean up their acts and enforce the laws that would help the Bay.  I don’t know about you, but I’m sick and tired of hearing about sewage spills and intentional dumping into the water we fish in. The best way I know to get involved is to write to your Senators and Representatives and ask them to support Senate bill S. 1816 and House Bill H.R. 3852 to reauthorize Section 117 of the Clean Water Act.  The Chesapeake Bay Foundation has simplified the process with its Online Action Center.  There’s also some great information about other avenues on their Action Alert website.  It’s totally free, and anyone can participate.

A six by two foot strike zone is not enough.  Let’s work to protect the sport we love by supporting a cleaner Chesapeake Bay!

Related posts:

Low Dee Oh!
Strike Triggers – Part 1

Posted Thursday, May 13th, 2010 at 10:58 pm
Filed Under Category: Fishing Reports
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Responses to “The Strike Zone”

  1. Paul says:

    Fascinating report and some very cool science Shawn. The Strike Zone depths confirm why we’re seeing fish in that general area holding deeper this spring.
    I’ve sent my messages to my reps and have already received their form letter responses. Hope they’re paying attention and see an opportunity to get on board.
    Thanks for posting and tight lines.

  2. der Fischadler says:

    Shawn;
    This work is one of your best efforts.
    Excellent description of what is happening in the bay.
    This article should be published in a major market publication. It’s that good.
    Mark
    der Fischadler

  3. Kevin says:

    Shawn,

    I echo Mark’s comments. I’ve witnessed the bay’s decline for over 30 years and it continues to worsen each year. Thanks for the links in your report, we all need to get more involved.

    Kevin

  4. Capt. Sonney says:

    Capt. Shawn,

    This was an excellent report on a subjuct few understand as wel as you and John Page williams. When trolling we know that fish stay at differment depths, both prey and preditor. So we place tageted lines at that depth to catch fish. Oxygen levels and temperture are key for their servival.
    I do hope you would send this to Fishermans Mag. or other publications as this article/report speaks volumes from the expects.

    Capt. Sonney

  5. daniel says:

    Awesome article, Dad. I’m with der Mark, this needs to be submitted and published in some periodicals etc.

  6. Shawn says:

    Thanks for the comments. Good to hear from Capt. Sonney. This entry has earned more than three thousand page hits, so hopefully someone will get the message.

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