Friday, August 16, 2013

2013 Connecticut Blue Crab Report #7

From Tim Visel at The Search for Megalops:

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

Program Report #7

August 16, 2013

The 2013 Blue Crab Year


  • Blue Crabbing Soars in Central Connecticut
  • 2012  Megalops Set has Survived In Some Areas
  • Western Connecticut Blue Crab Habitat Failure and Recovery
  • What Happened in July 2011 Answers to Habitat Questions – Hydrogen Sulfide and Estuarine Health


Blue Crabbing Soars in CT


With tides reducing in intensity and some good weather days and nights, blue crabbing surged in central Connecticut and new eastern reports continue to be very positive. The Connecticut River fishery increased as crabs headed up river, look for the best shore crabbing at high tides and deeper holes remain very productive for boaters. The Nott Island Bay, the easterly side of the Connecticut River opposite Essex was excellent. Some 100 to 125 count catches were made during the first week of August. Catches at night however at slack water remains unpredictable, and a tremendous eel population is now present in the Connecticut River; I used Vexar™ netting bait bag material, but (August 30, 2012) even that will not prevent a poor catch. When the eels show up, crabbing is very difficult.



What is being reported is that large male crabs are moving upriver and generally the upper reaches are producing the best catches. And, at this time, I think I better take off the gloom at least for central and eastern Connecticut as this season appears to be approaching that of 2012, and has the potential to even improve beyond that. The 2012 Megalops set has appeared 60 days late and in heavy concentrations in eastern CT (May 15, 2012) and new reports in the Mystic, Thames and Pawcatuck Rivers mention a huge increase in the number of 1.5 to 2 inch crabs; these crabs should be 4 inches by December and be next year’s legal crop. I appreciate the new reporters for the Mystic, Thames and Niantic Rivers—thank you!

So, as catches now exceed 10 crabs / hour or more in central CT, the gloomy reports (March 26, 2012 and April 17, 2012) need to be changed for the central and eastern portions of the state (see next section).  The West however largely remains in the doldrums. It’s just very poor blue crabbing. Hoping to see a good Megalops set survive there in a few weeks, with New Haven to Stonington, now the place to crab. 


See you crabbing,




The 2012 Megalops Set Has Survived


Although about 60 days late (waters were very cool this spring), the 2012 Megalops survived and is present in increasing numbers in Central and Eastern Connecticut.  My spring predictions of March and April pointed to widespread winter mortality for all three years’ adults – 3 to 4 and now the Megalops set. This winter kill did not occur for adults and 3 to 4 sizes and apparently did not occur for all of the 2012 Megalops.


It just shows how resilient and tenacious blue crabs can be and my predictions of gloom premature, but let’s be honest, we had Sandy, heavy snows, several powerful coastal Nor’easters, the most snow (80 inches along the coast) since the 1950s, the huge blizzard Nemo and snow in northern New England until May. Spring water temperatures were very cool and like the Chesapeake, I feared the worst. Most recent reports from the Niantic River, Thames River and now Mystic River however show tremendous numbers of 1.5 to 2 inch crabs, next year’s legal size crabs. I don’t feel that there is enough time left in the growing season to reach 5 inches this year, but I thought the hibernation period was too long also.

With 90 days to 120 days we might need to rethink when blue crabs begin to hibernate, I thought late December, but now perhaps late January?


A big question remains in the west, once a huge producer of post Megalops blue crabs 2006 to 2011. A good set here (2013) will be a great sign as I believe as the lobster fishery before western areas produced larval blue crab stages for the central and the eastern sections. In 1980s, about a third of female sublegal lobster population in the west was “berried” or carried eggs. The larval drift for Stage 1 to Stage 3 lobsters to the east was tremendous (at that time) and species habitat carrying capacity of high density will naturally seek areas of lower density. I think the same thing can be said of western CT with the blue crab reversal after 1998. The west may be the largest supplier of Connecticut Megalops as evidenced by movements east of immature blue crabs in 2010 and early 2011. Some of the densities of small crabs reported in the Westport/Fairfield salt ponds in 2009 and 2010 were incredible. If western CT was a large Megalops supplier of the central and eastern sections, then reduced catches might be inevitable in other areas; western CT could be our blue crab nursery and why finding areas of Megalops sets so important there.  Look for the first signs of post Megalops blue crabs in sandy areas along the shore in minnow beach seines by September. Some of the best blue crab larval stages can be observed in them (August 30, 2012) and the appearance of small crabs in the west would be a very positive signal for all Connecticut blue crabbers.


Western Connecticut Blue Crab Habitat Failure and Recovery


One of the most interesting aspects of the natural ecology of embayment systems is balance, and the other is ecological voids. Nature hates a vacuum and that is true, but what takes years to happen can be gone in an instant and what happens instantly can take years to restore, in other words, we have habitat succession in the marine environment also.


One only has to look at terrestrial forest fires and marine hurricane impacts to experience this change.  But what about the habitat succession; we can’t see, we can see the impacts of beaches swept away by storms but will we see the kelp/cobble stone forests that often follow?  Forest fires are terrible events for those in its path but years later species that needed grassland habitats thrive, while those that needed the forests before decline, a balance between habitat types and the populations that need each type? Do we know enough about habitat succession and population dynamics of marine fish and shellfish in the marine environment?  No, absolutely not, we haven’t even begun to understand it or study it for that matter. We learn about marine habitat succession from fishers, as we did first about terrestrial succession from hunters. Similar to terrestrial habitat succession, (drought and high heat precedes forest fires, while rainfall signals a long term renewal of the forest). Marine habitat succession is governed also by energy and temperature.


Hunters would head to grasslands to seek species that needed that habitat, fishers head to “structure” to catch species that need it. Talk about structure to any freshwater bass fisher, and you will soon find they are keenly aware as to the value of structure to overall fishing success.


But what about blue crabbing, what made the 2006 to 2011 blue crab populations soar in western CT? What do they need, what is their habitat balance in regards to habitat succession? These are questions that need answers if we are truly to understand one of the largest habitat reversals in a century.


Did western CT blue crabbers experience something of a habitat successional event in 2011, yes I believe they did.


Hydrogen Sulfide And Its Impacts Upon Estuarine Health.


Sapropel and western CT river life systems may provide response to western CT blue crabbers. The truth of the matter is that we just don’t know much about sulfide toxicity in western CT. It is an area of research that is lacking even into today.


In many respects my response to questions from the western crabbers in 2012 is a combination of several factors low oxygen, freshwater toxicity, chemical toxicity, hydrogen sulfide toxicity and disease.


While all of these factors should be considered, I believe low oxygen/hydrogen sulfide toxicity to be the primary reason for the apparent habitat failure. Many blue crabbers pointed to the West Nile treatments and that deserves a look and I did issue a special report (Pesticides and Blue Crabs on July 24, 2012) about this, I also looked at disease and habitat life cycle stressors including oxygen and chemical factors as contributing causative disease factors, but central and eastern blue crab populations remain to my knowledge relatively disease free. So I looked at a key concern of mine the habitat impacts of high heat, low energy and high organic deposition, particularly leaves oak and maple as acidic sulfur respiration pathways leading to hydrogen sulfide buildup and fish kills.


And, as I usually do, I look at what is in print, in the historical records and current research. After researching the problem for about a year in regards to western CT rivers and harbors, I found very little written about the impact of deep deposits of organic matter (leaves).  And when pollution of rivers did grab a national attention here in the US, its focus was upon the chemical manmade aspect of non natural “polluting” substances, entering water courses not natural ones such as organics, leaves for example. A consensus upon pollution would itself contain a biased point of view, how could something “natural” also be considered a pollutant. This public policy component would initially tend to the analytical chemistry descriptions of measures for manmade substances for pollutants.


When examining the historical records it is important to recognize a resource bias in the scientific community at the turn of the century. During this period lakes were the resource of concern, still important for water powered machinery and drinking, however rivers or harbors were not high on the priority list. In fact, rivers were thought to be the best way of “receiving” factory wastes, so it was much to our repugnance a “reasonably use” of pollution policy existed.  Until well into this century, one only has to read the three hour speech to the CT Agricultural Board in 1886 about pollution which the editor of the Hartford Courant, then Mr. J. B. Olcott described walking along the Quinnebaug River with cotton soaked in glycerin stuffed into his nostrils to block out the smell from the river. Not doing so would accordingly cause one to instantly wretch. This was a common practice during this time in Connecticut unfortunately along many riverfront factory communities. Therefore, is it not surprising that some of the earliest river studies of the biological impacts of river organic matter pollution came from Europe and not from the United States. Some of the first studies are from the Baltic region, especially Germany and Poland. River fisheries were very important in Europe (fisheries, drinking water) so impacts to them were first studied and the first research on the impacts of high organic matter is from them. The first formal study of putrefied organic matter, and biological impacts upon rivers was developed by Kolkwitz and Marsson at the turn of the century. In 1909, they developed what they termed, a Saprobien system for the assessment of organic pollution, and in the 1950s, 1960s and 1970s this bias (chemical not organic pollution) for lakes and not rivers continued here in the US. In the 1930s a worldwide conference about Sapropelic formation was held and at the urging of Parker D. Trask of the US Geological Survey just prior to World War II, the paper of recent Marine Sediments was finally printed in 1955.  In 1971, H.B.N., Hynes of the University of Waterloo, Ontario, Canada, published his now famous book, “The Biology of Polluted Waters” (University of Toronto Press 1971) he mentions this bias in regards to the “well known” classifications of Saprobien System for rivers. “But perhaps well known is too strong an epithet to use because although it is widely used on the Continent, it is rarely mentioned by American or English authors.” The Saprobien System as defined at the turn of the century will be recognizable as a slightly different system for lakes today, not rivers. And the largest constituent of Sapropel in CT now appears to be leaves, and depleted oxygen (warm water) conditions – “a habitat history” or much longer cooler and then warmer periods.


The basis of this classification system is the theory that when a river system receives a tremendous load of organic matter (leaves, grasses, bark, twigs, etc) it would result in a series of “zones” of decreasingly severe conditions for plants and animals downstream. A brief description of the Saprobien System is below:


PolySaprobic – Zone of gross organic pollution organic matter with little or no dissolved oxygen and the formation of sulphides (now sulfide).


MesoSaprobic – less organic matter and grades according to the numbers of indicator life forms


OligoSaprophic – The zone of recovery where the mineralization (breakdown) of organic matter is complete and oxygen content is back to normal and a full range of plants and animals occur.


In simple terms, western Connecticut rivers and estuarine areas could now be termed PolySaprobic, favoring the condition of sulfides and extremely toxic to blue crab Megalops and adults. It is now strongly suspected in the black water deaths (largely fish kills) at the turn of the century. It is suspected that floods following years of hot stagnant conditions ripped open Sapropel deposits (black gelatin) releasing enormous quantities of sulfides causing massive fish kills, by “black water” usually accompanied by strong sulfide rotten egg” smells. Passive deposition of leaves and organic matter in coves in Eastern CT such as the North, Middle and South Coves in Essex in which oak and maple leaves have collected are good examples. Over decades in areas even 10 feet in depth have layers of leaves, the western Connecticut rivers may have received just as much organic matter by active watershed transport, organic matter from storm water, and ripped into “brown bottoms” of organic oatmeal in just a few days.


I believe that is what the western Connecticut crabbers were trying to tell me in July 2011 (see Report #12, August 2, 2011; Report #14, August 19, 2011) that heavy rain had ripped into sulfide deposits killing crabs in place. Irene may have brought down additional organic compost then followed by Sandy. The sulfides now released by these organic deposits (warm water and less oxygen favors deadly Sapropel deposits) which lower pH levels could have resulted in a western Connecticut die off of blue crabs not seen here for a century. I will also add that lower pH tendencies to increase the toxicity of insecticides as detailed in label warnings. Many insecticides have both high heat and low pH application warnings.


In simple terms, it is as if someone dumped overnight 5 feet of compost on your yard, the lawn would quickly die, you could see it, and until it is raked off, no lawn. The same thing happens in the marine environment, usually not as dramatic as floods carrying down decades of built up watershed organic matter at a time, but a gradual build up as temperature rise rot. In this case, rotting leaves may have covered valuable blue crab habitat.


In periods of cold (more oxygen in water) and frequent strong storms Sapropel accumulations “melt” away as storm activity washes it from tidal areas. Several western crabbers have asked me about Sapropel (after Report #5) and many blue crabbers have seen it, but know it best by its common name, black mayonnaise. It is also in the location of blue crab populations making its toxic impact, event (storms and hot weather) temperature related. Organic deposits with sufficient oxygen (cooler water) seems to be a good blue crab habitat type but very deep deposits in hot weather tends to be Sapropel. That explains to some extent hot weather warm water blue crab jubilees down south or here in New England late summer and the turn of the century black water deaths. One of the most notorious black water deaths from the last century occurred on Long Island, New York in Moriches Bay between July 29 and August 4, 1917. Here tens of thousands of winter flounder died and then putrefied in the heat. Although today very little is written about Sapropel itself, in Southern New England from Cape Cod to Long island, in shallow warm coves and bays, with reduced tidal exchange, it has often become a dominant habitat type. It is in hot weather Sapropel is toxic to most forms of requiring oxygen marine life and sheds ammonia, a brown algal nutrient.


This also explains how great blue crab habitats such as those in pre July 2011 habitats quickly turned deadly for blue crabs resulting in a DIP “dead in place” blue crab observed die off.


More about Sapropel and Saprobien System in later newsletters.

Email your blue crab reports to:

Every observation is valuable as we learn more about our blue crab population. 

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 at

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


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