Friday, August 9, 2013

2013 Connecticut blue crab report #6

The Sound School – The ISSP and Capstone Project Proposal

Building a Network of Citizen Monitors
The Connecticut Blue Crab Population Habitat Study 2010-2015
You Do Not Need To Be A Scientist To Report!

The Search for Megalops

Megalops Report #6

August 8, 2013

The 2013 Blue Crab Year

  • Large Blue Crabs enter The Connecticut River up to Essex/Nott Island
  • Old Lyme Rivers Have Excellent Crabbing – Branford River Crabbers Catch “Pole Crabs”
  • A Few Milford Reports – Increased Western Crabbing Success; Saugatuck River, Westport - Perhaps a habitat study area for Blue Crabs?
General Information
The blue crabbing continues to be very good and Central Connecticut outstanding, the eastern cove reports also remain good. The highest catches however remain between New Haven and Old Lyme. The good news is that more frequent reports of 1 to 2 inch size are being made – that is a good sign, but historically, it has been western CT that has been the largest juvenile blue crab producer.  In a June 30th 2011 report, one western CT crabber describes the run as three distinct Megalops sets with about equal size distribution.
32 keepers – 1 soft shell; 150 crabs observed – run about 40% 1.5 inches to 2 inch; one year old or less; about 30% 3 to 4 inches, two years old or less; about 30% legal, 5 inches and up, three years old or more. (July 2011) [1]

But in the 4 days after a heavy rain/flood in July 2011, the run dramatically changed to 70-75% legal to 25% sub legal with many reports of 1.5 to 2 inch blue crab die offs (Report #12 August 2nd, 2011). Within two weeks most of the 1.5 to 2 inch blue crabs were dead in Western CT (Report #14, August 19, 2011). What I thought was a local die off in reviewing western reports was a huge habitat event and I missed it, but by July of last year, I became suspicious (see reports of July 9, 19 and August 16, 2012).  It was a much larger habitat event and it would involve it seems the entire western coast. Since 2011 the number of western crab reports has declined while the number from a central Connecticut has dramatically increased. The few western CT reporters continue to look for blue crabs and have asked why? what happened?  I do appreciate those individuals who still report weekly “no crabs”; that is dedication to Citizen monitoring! 
The next newsletter will contain a response to those questions and later newsletters will have sections about the western habitats. Again, many thanks to the Blue Crab Forum – Info for archiving the Megalops Reports from 2011 onward, and including them on the Northeast Crab Resources bulletin board.  It makes trends and changes so much easier to see and learn from crabber reports.
With the weather and crabbing improving, I will see you at the docks,
Tim Visel

Blue Crabs Enter Connecticut River up to Essex at Night
If you caught striped bass between July 10 and July 20, on Long Sand Shoal, Old Saybrook, chances are their bellies were stuffed with small blue crabs. Reports mentioned blue crabs on Fluke jigs and chunk bait between Cornfield Point and Saybrook Light offshore during this period. Dock fishing at Saybrook Point shortly afterward nearly became impossible as fishers complained about the constant loss of striper and bluefish bait. The size of this sublegal blue crab population is not known but roughly in a patch from Cornfield Point to Saybrook Light north of the shoal, it is thought they were trying to enter the Connecticut River. The July 23rd report had barely been sent out when the NAO weather pattern intensified (Special Report #1 March 26, 2013 and Report #2, May 15, 2013)_ driving heavy rains again into Connecticut.  Connecticut crabbers have seen at times terrible crabbing conditions, cold to hot and often with incredible rains.  This storm pattern looks to continue driving Gulf moisture north with heavy rains. The CT River salt water wedge was slowed by the heavy CT River fresh water flows recognizable by the waters brown coloration. But finally, on July 27 and 28, large numbers of both legal and sublegal crabs were observed moving up the Connecticut River to Nott Island.  Look for the NAO weather pattern to weaken slightly and air masses resume a more west to east zonal flow. This should reduce the precipitation allowing salinities to rise signaling crabs to move up the estuaries for mating. Reports indicate that this is indeed happening now. Blue crabbing has dramatically increased at Essex (August 4, 5, 6) although the run is 5 to 1 sublegal to legal size crabs, with steady weather conditions look for Essex and Connecticut River crabbing to greatly improve.

Old Lyme Rivers Still Excellent – Branford River “Pole Crabs”
Blue crabbing at the mouth of the Connecticut River especially Old Lyme tidal rivers continues to be excellent. Some reports mention that larger crabs have left the shallows and can be found in deeper sections; that happened the past two years at the same time (Report #2 August 2nd, 2011) and (Report #6, July 19, 2012). Look for this division to increase as summer water temperatures max out around August 25th to 30th. At the same time adult blue crabs seek to avoid stagnant salt pond and cove waters in high heat, often with low oxygen levels (not sulfide if you smell sulfur, “the rotten egg” smells change your crabbing spot!). This is exhibited by” pole crabs” blue crabs clinging on to marina and dock pilings, or clinging to salt marsh edges. Pole crabbing in the Branford River is now increasing as waters warm.  In 2010, the pole crabs were so prevalent in central CT, that many crabbers crabbed all day without any bait! It is thought that the slightest hint of sulfides from the breakdown of organic matter (see next section response to western crabbers) crabs will leave the bottom and move higher, attaching to poles. Some of the reports of crab jubilees in more southern waters mention this factor. Crabs during jubilees crawl on land to escape low oxygen waters (see Report #1, April 17, 2013). Dock poles provide a handy place to get into the surface water shore chances of greater oxygen levels exist. Fish will also exhibit this surface behavior and just before huge “fish kills” menhaden will often appear on the surface swimming in circles, trying to breathe just before perishing. It is often a surprise therefore, that crabbers often do well crabbing along the immediate shore during these low oxygen events. The rings or edges of salt ponds and coves often have a narrow band of “life” during those hot weather days. This is due to the tidal flux of oxygen rich saline waters into the ground waters at high tide (hydraulic pressure) only to be released slowly as the tide ebbs. It is possible to feel this cool oxygen rich saline waters leaving with your feet in areas of steady ground water release, sometimes, it will even bubble up and flow out from beach fronts. Crabs notice this cold water saline ground water and wait buried in it for the next tide. Areas that have pole crabs at high tide usually have much poorer slack low tide blue crab catch rates. At those times, boat dippers along the edges do better. Watch for pole crabs in sluggish and poorly fished areas (often marinas or in side coves) these areas tend to be better at high tides, especially trapping. (See Estuaries, Vol 27, #3 pg 551-560, June 2004, The Roles of Anoxia, H2S and Storm Events in Fish Kills of Dead End Canals of Delaware Inland Bays).

A Few Milford Reports – Increased Crabbing success/ Saugatuck River is Key Study Area for Western Blue Crabs

As what happened in 2012 (see report #6, July 19, 2012) a few western reporters now report limited blue crab catches in Milford. This is a good sign for certain, as most of the pre July 2011 western crabbers now head for areas between New Haven and Old Lyme. The limited catches (between 5 to 10 crabs/trip) is much lower than trip reports over 30 crabs to 50 per trip or more for central and eastern CT, it is a positive sign nonetheless. It is improving finally! I do appreciate the few western reporters who continue to look for western CT crabs. A few crabs have been caught in the Norwalk River (The Maritime Aquarium at Norwalk) but it looks like the Saugatuck River in Westport may be the best place to conduct a habitat survey for a possible blue crab habitat failure.
One of the signs of a habitat failure is an overwhelming deposit of terrestrial leaves and organic matter in the marine environment. One group Earthplace of Westport, CT has been detecting an increase in leaves on the bottom of the Saugatuck River. In an October 23, 2011 article in Westport News, is found these quotes regarding a beam trawl net survey conducted by Earthplace, a Westport nonprofit environmental organization and comments by Richard Harris in the article, just a few days after Irene which hit late August  2011, mentions that the Saugatuck River had already been found to contain leaves.

Reprinted with permission of Westport News,  “…Harris frequently notices that “old brown color” as the director of Harbor Watch/River Watch, a water testing and monitoring program run by the Westport non-profit Earthplace that operates in the Saugatuck River, Norwalk Harbor and other local waterways…Harris added that leafy buildup on riverbeds is uninviting for bottom-dwelling fish.  “It fouls the bottom, so the fish that lay eggs such as flounder and other bottom-dwellers can’t use the bottom to raise their young and use it as a nursery,” he said, “Basically once the bottom turns into that kind of condition for them, it’s kind of hands-off for them.”[2]

An excess of organic matter in a river system can drive oxygen levels very low with a sudden rise in toxic sulfides. At the turn of the last century (1905) researchers in Europe had devised a graduated system for assessing such organic matter “damage” called the Saprobien System. It is the foundation for the name Sapropel, a putrefied and sulfur rich marine compost, commonly called black mayonnaise.  It is this substance that has been shown in high heat, low oxygen conditions to produce hydrogen sulfide, that rotten egg smell during quiet hot August nights.

Blue crabs especially blue crab larvae are very sensitive to sulfate compounds, in fact in a 1996 issue of Environmental Contamination and Toxicology, Vol. 31, #2, pages 193-195, regarding Megalops and larval stages of Callinectes sapidus (blue crab) researchers found that blue crab larvae were killed by minute traces of sulfate compounds. We are just beginning to learn about the toxic impacts of hydrogen sulfide in high heat organic rich habitats. Recent research in the Narrow River Pettaquamscutt Lakes, Rhode Island, Arthur Gaines Maritimes, Vol 35 #2, May 1991, found hydrogen sulfide levels at ten times those found in the Black Sea and (Luther et al) Estuaries Vol 27, #3 pages 551-560, June 2004 reports upon hydrogen sulfide concentration in poorly flushed Delaware inland bays are amongst the highest reported in marine systems, page 555.
The extent of sediment pH, sulfide toxicity is just now being looked at again, reviewing the Saprobien system from the last century. It may have the decisive answers for blue crab habitat quality in low oxygen, high heat conditions.  The Saugatuck River might be a good place to look at this possibility.

Every observation is valuable as we learn more about our blue crab population. 
Email blue crab reports to:

The Search for Megalops is part of a Project Shellfish/Finfish Student/Citizen Monitoring Effort Supported by a 2005 grant to The Sound School from the National Fish and Wildlife Foundation grant #2005-0191-001.
Program reports are available upon request.

For more information about New Haven Environmental Monitoring Initiative or for reports please contact Susan Weber, Sound School Adult Education and Outreach Program Coordinator- Email:

The Sound School is a Regional High School Agriculture Science and Technology Center enrolling students from 23 participating Connecticut communities.

[1] With ideal growing conditions subtract a year, it is possible to grow 2 inch to 5 inch the same season as the 2010 season showed.

[2] “Not all is looking up on the Saugatuck's bottom,” on  Paul Schott,, August 2011

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