[BlueChip]

The Blue Crab Year -
The Search for Megalops – August 2, 2011- Report #12
You do not need to be a scientist to report!

Reports 1 to 11 are available – email Tim Visel at tim.visel@new-haven.k12.ct.us

• Boaters’ catches surge past shore crabbers in many areas; heavy rains suspected.
• Welcome East Coast researchers: New York, Georgia, Virginia and Maryland studies express interest in Connecticut Megalops search.
• Western crabbers alarmed at dead crabs following intense heat and street water runoff event.
• Moon tides called a marine Metro-North for small crabs.
• Gulf Pond, Milford identified as possible source of small blue crabs for area.
• What about Megalops, when do they set?

This report was off to an excellent start, many positive reports early at the end of the previous week. Although crabbing had definitely improved overall in the central and western sections, it does not represent as yet the observed abundance last year for the same periods. I had even picked up new reporters for Westport and in the Saugatuck River, Guilford and Old Lyme, Connecticut. Reports included tremendous increase in small crabs at RT 146, Guilford; many crabs now at the Sluice Dock, Guilford, a surge of 4.5 inch crabs in the Oyster River, Old Saybrook and a possible wave of 2 inch crabs in the Branford River, a first sign of crabs entering the Saugatuck River also. Then the extreme heat came followed by heavy tropical like rains.

The bottom dropped out of catches turning sharply negative then followed by reports of dead crabs on July 26, 27, and 28th. Even the run distribution changed after positive numbers: western 50/50 about half of the catch was now legal and even in central sections for the first time it had dropped to 75% legal and 25% sub legal, western and central reports count/keepers surpassed the teens, had climbed into the 20’s and some even higher. Eastern Reports are so few I can’t comment about catches in general, then the heat and heavy rains hit with one/two punch and catches/reports dropped and turned negative. If reports continue to mention dead crabs especially that 1.5 to 2 inch crab that could impact the remaining blue crab year, I’m not certain.

Some reports mentioned a 50% drop in catches compared to the last trip and some after catching a few crabs simply gave up. Just a few days before these areas were good to excellent. Several reports mentioned the dramatic difference in water temperatures and clarity. The water near shore felt “hot” or the area was full of brown water. Three veteran crabbers report of seeing whole dead crabs the following two days. After heavy rains two other in central areas expressed concern for what had been relatively quiet tidal areas, were now for a period a “rushing torrent of brown water- hot brown water no less.”

I feel it’s safe to say that rain hitting these 100° plus pavement surfaces delivered a warm thermal discharge that was over 80°. This event comes just two weeks after emailing a colleague about the problems with very hot storm water for Long Island Sound fisheries. Chester Arnold, a friend and at one time coworker, was one of the first University of Connecticut researchers to recognize this important area (1980s). He developed with several others a program called “NEMO” – Nonpoint Education for Municipal Officials. The program is now a national model and supported by the Connecticut Department of Environmental Protection (DEP) and is available online at http://www.nemo.uconn.edu/ GIS and computer simulation details the impacts of impervious paved surfaces on watersheds, such as those surrounding Long Island Sound. Many feel (myself included) that hot street storm water flows will be one of the largest environmental issues (with global warming) confronting Long Island Sound managers during the next century.

So to respond to several questions around salinity and water color, the browns are usually attributed to partially dissolved leaves especially oak leaves or silt / soil from street basins. The warm water can shock organisms but the largest factor is that warm or hot water is able to retain less dissolved oxygen than cold water. So it’s not just one factor but three: thermal shock, possible oxygen deficiency and finally salinity shock- salt or brackish to fresh water in just a few minutes. It seems that these areas should quickly recover, stable salinity and temperature profiles in a few days, but storm water surges can overwhelm estuarine organisms and while fish flee or try to swim out of the impact area, crabs tend to grab onto the bottom and resist being washed quickly downstream. This defense mechanism may be detrimental in these instances and surges such as the one experienced a week ago can kill blue crabs and nearby Megalops sets. Most sub tidal species: crabs, shellfish, benthic fish species can take some salinity shock, but going to hot fresh water that perhaps was low in oxygen most likely killed the observed dead crabs. They did not quickly “flee” the area. It’s discouraging to see this and I have seen something similar with my son Willard in 2004-2005 when a sudden spring fresh set killed thousands of 2” crabs in the Connecticut River by the DEP Baldwin Bridge launch ramp. It was May and we observed very dark brown water and along the shore, inches deep of small dead whole blue crabs. (It was too cold to be shedding.) These crabs I believe were killed by a huge fresh water surge a few days before. This event last week is different, as it was hot water not cold and so sudden as compared to a three day gradual rise. Mortalities last week could have been from multiple factors, salinity, oxygen and temperature. It would be interesting to see how quickly impacted areas recover, especially those key 2 to 3 inch sizes.

A long time CT River crabber (boat only) who used crab pots on the lower CT River only caught crabs in the deepest river and channel areas- “the shallows were completely dead.” (No crabs.) They are in the deep holes. He had no trouble catching crabs; in fact to him the crabbing had improved.

If you were catching crabs from a boat last week and did well, you were not alone; the fact is in many areas, the boaters did much better than the “shore” crabbers. But, to really appreciate the impact of these rains on one location, I have listed a series of trips by one of my most consistent reporters.

o June 20th- 12 keepers, 2 soft shells, run 50% 1 to 2 inches observed about 100 crabs today;

o June 30th- 32 keepers, 1 soft shell, observed about 150 crabs total, run 40% 1.5 inches; 30% 3 to 4 inches; 30% legal length;

o July 13th- 28 keepers, 6 soft shells, small crabs too numerous to count, run 1-2 inches 60%; 2 to 5 inches 20%; legal size 20%;

o July 27th- 15 keepers, 3 soft shells; observed about 75 crabs total, 80% 1.5 to 2.5 inches; 10% 3 inches and 10% legal size; (Water was really warm for the first time in 10 years of crabbing here or better, I saw a good number of dead crabs.)

One factor related to heavy flows of fresh water into streams and rivers is the nonappearance of a Connecticut River Blue Crab Fishery. The blue crabs according to my last report have not yet appeared at the Essex Town Dock. I spoke with a crabber recently who came down “to try”. He had been crabbing at the Essex Town Dock for more than 30 years, the best years in his mind were hot and dry, less rainfall. He had tried for about 3 hours and not a crab, but he just wanted to “check it out – too much rain,” he commented.

Last week the shallow shore areas were not the place to be but the deeper areas did much better. In fact some recent “just in” reports for July 29, July 30 tell of much better catches in the East River, Guilford and Oyster River, Old Saybrook.

I have received some inquiries from New York researchers and crabbers. Please continue sending in reports for New York blue crab habitat/catch observations even though the Sound School is in New Haven, Connecticut; we are all on one Sound. I’m especially interested in reports from Port Jefferson to the west and how this year compares with last year.

Also, researchers from Georgia, Mark and Virginia are now on the distribution list, Welcome aboard! Several exchanges of information here already occurred. Thank you for the interest.

Thanks again to Steve Joseph one of the aquaculture teachers here through which we have obtained some live shots of “yellow face blue crabs” for the University of Connecticut Sea Grant College Program. The term is not ours, but belongs to that Oyster River, Old Saybrook crabber who caught a whole pail full in just a few minutes a couple of weeks ago. It shows a distinct yellow band (like someone painted the face area around the mouth.) They show no other signs except they are rock hard shell crabs, packed with meat. (Nothing has been linked to anything being wrong with them). Two crabbers claim they are crabs that missed the fall shed, the shells are old, and Steve Joseph did mention that the yellow face crabs showed scraps, scratching on the shell surfaces and looked like they had been in the same shell for “a long time.”

On a more positive note, the Gulf Pond, Milford area has been identified as potential prime Megalops habitat. The reporter described moon tides reaching high up in the marshes and moving large numbers of small crabs out: a “marine Metro-North” so to speak. This impact of strong marine tides acting to move crabs has been mentioned several times.

Gulf Pond could be the source of small blue crabs observed off the West Haven beaches and predated upon by fluke earlier in the summer. The report mentioned (a flashlight nighttime observation) observing many small crabs being carried out to the lower pond past the Buckingham Avenue Bridge. The bridge apparently bisects this coastal salt pond and could be the source of crabs at Silver Sands State Park and West Haven beaches. It will be definitely considered for a Megalops set serving site next year.

What about Megalops?

Several observers have asked about the blue crab Megalops and it being the title of the monitoring effort, they are good questions!

First of all, blue crabs have a pre Megalops staged called Zoea (Zoeal stages) and looks like a small shrimp or lobster; they really don’t look like a blue crab and are tiny. A good bioscope or microscope is needed to see them.

They grow past several stages drifting with tides before becoming a Megalops and at this point they do resemble a lobster or crawfish with a central body, tail and bilateral claws. It’s the Megalops that “sets” – it sinks to the bottom and enters the next stage of becoming a true crab. They begin to take on the appearance of a mature blue crab or “star” when they are about the size of a pea, by the time they reach dime size; the carapace points are very much evident. At this time, they tend to prefer bottom cover, eelgrass margins, estuarine shell and submerged vegetation/debris. They need to hide from a wide range of predators (including at times other crabs) and seek shelter in the salt marshes along our coast.

It’s at this point they become vulnerable again to tides: ebb tides can carry small crabs from creeks and rivers out to Long Island Sound and potential meals it seems for a very good sized population of fluke along our shores, but this year also blue fish and striped bass as well. They need as small crabs, healthy sub tidal habitats like salt marshes containing salt ponds to grow. It seems to be a coupling of two critical habitat types: marshes with deep sub tidal habitats, one without the other carrying capacity appears to be diminished. This may be the largest difference between western and eastern areas: the ability to catch, hold and mature Megalops sets. How do we locate these critical (new word today) “essential” blue crab habitats; we look/search for the Megalops.

The Search for Megalops
Preliminary Sampling Methods/Protocols – August 2011

The movement of small crabs by tides and currents is well known. I recall fishing for striped bass using green crabs with my father and brother, Ray in the 1960s. We lived next to a small tidal creek in Madison, CT and would fish the ebb flow when all the “free food” got swept out of the creek to an offshore assemblage of waiting hungry striped bass. We just hoped they would see our drifting crab bait as well. They did. So it is possible for crabs to be moved around but not the Megalops, once they set they want to stay and hide. Their soft bodies are easy prey for almost everything and the attrition loss from this stage must be extreme. Some researchers have speculated that only 2 to 6 adults will make it from a 2 million egg sponge female crab. So the presence of Megalops in a particular habitat should indicate the site of set. To check/sample for Megalops, two items are needed, a sampling net and collection bag or jar. In addition because the Megalops looks like many other crab species, we need to develop a “key” so that species can be distinguished from other crabs such as lady or green crabs. Mickey (Howard) Weiss mentioned last winter an interest in developing an Internet based video key for many crab species. Many marine biologists will recognize Dr. Weiss as the founder of Project Oceanology.

I have asked a former DEP staff person (now retired) to help us with the proposal next year. His name is Alberto Mimo. He was the person to originate and largely developed the very successful DEP monitoring student/citizen program called Project SEARCH. Project SEARCH was developed for fresh water habitats. To quote from the Project SEARCH foreword:

Project SEARCH was created and developed by Alberto Mimo with the Office of Communication and Education in the Connecticut Department of Environmental Protection (CT DEP) in 1986. This program was started to provide students and opportunity to participate in field science education and help the environment by getting involved in research, monitoring, and inventory of a local stream.

In addition, I have also asked a few of the DEP Project SEARCH staff and others associated with its development if survey protocols could be modified for the Search for Megalops as a saline sub tidal monitoring effort. The initial stage of the Megalops project is a basic presence/absence study. If some of the sampling techniques and survey methodology to collect riffle dwelling organisms could be modified (with Project SEARCH serving as a guide) for the marine environment. Project SEARCH (which we use extensively at the Sound School) indexes habitats based upon ratio of riffle dwelling organisms in fresh water streams. It forms a statewide citizen/student monitoring effort. A predetermined index is used to classify habitat based upon the number and ratio of organisms collected. All the Project SEARCH documents have been put online by CT DEP staff; they can be found at http://www.projectsearch.org/ It represents years of work and it is quite extensive having sections for every aspect of the program. If you are interested in fresh water stream habitats or in surveying fresh water streams, I can’t recommend the program enough. We are considering these types of research / reporting efforts suitable for high school graduation Capstone Projects or civics / FFA public speaking events.

What makes the Search for Megalops feasible for high school academic year projects is that the blue crab Megalops stage is unique in its ability to delay in cooler weather transitions to “star” crab stages. (If this sounds like a species defense mechanism against cold temperatures it is; compares to the specialized bottom tail skin cells in winter flounder that activate in low oxygen / high temperature conditions). Megalops surveys could take place in the fall or early spring. I suspect some areas that obtain a good Megalops set in the fall get killed by storms or cold during the winter. Other areas in the western parts of the state (especially between Stratford and Fairfield) should contain enormous quantities of Megalops just from the past two years’ observations. I also anticipate some of the eastern CT rivers / coves should also have some, the Mystic River and Poquonock River estuaries should be good field study sites; western locations such as the Mill River (Rippowan) Restoration Project should also be surveyed, for Megalops and perhaps biodiversity rejuvenation together.

For those interested in some very good pictures of the Megalops – they are available online; see the Smithsonian Environmental Research Center K-12 Education Blue Crab Online Resource: http://www.serc.si.edu/education/resources/bluecrab/lifecycle.aspx
This fact sheet has some excellent diagrams and photographs as well as a detailed life history explanation.


The continued reporting by many new and veteran crabbers is so valuable to our study and I thank each for their contribution and hope they continue to do so.

Observations this year will help guide the survey methods for next year.

Every observation is important you do not need to be a scientist to participate!

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.

All observations are valuable; please email them to me at tim.visel@new-haven.k12.ct.us.

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 susan.weber@new-haven.k12.ct.us