[BlueChip]

The Blue Crab Year -
The Search for Megalops – July 11th 2011- Report 8
You do not need to be a scientist to report!

Reports 1 to 7 are available – email Tim Visel at
tim.visel@new-haven.k12.ct.us

• Something is happening here- Branford to Old Lyme Crab catches surge
• Blue Crabbing Improves as Temperature Rise in Central CT
• Third Megalops hatch confirmed in Greenwich
• Connecticut River salt water tidal wedge reaches Essex Town Dock on July 2nd, US Geological Service Information
• Adult Blue Crabs observed moving east at night along West Haven shoreline

The past five days have seen a marked increase in crabbing success in Central CT. Catches here surged from New Haven to the Old Lyme shoreline. Although the western portion of the state crabbing remains outstanding: the central sections are now picking up. Some reports of seeing numerous crabs in the Farm and Branford Rivers, Hammonasset River, Clinton Harbor and the first reports of Blue Crabs in North Cove, Old Saybrook and off Point of Woods, Old Lyme. This account is with a report of a second podding group movement behavior of large patches of Blue Crabs moving east along the West Haven beaches at night. This appears to be a natural process of high density to low density dispersal, apparently using the ebb times or one comment, the strong moon tides may act as a travel assist. Blue crabs compete for space and food and can be very aggressive. (I think anyone watching Blue crabs fight over a piece of bait will agree,) so with so many small Blue crabs in a small space podding, in this case may extend or increase the carrying capacity of our Long Island Sound. However, the reports of such numbers of Blue crabs moving in a concentrated way along the shore is, I believe unprecedented. The best example of this movement might be in Clinton Harbor. One crabber I spoke with, until recently, was taking home four to twelve crabs after a few hours with two traps. On July 5, he caught 42 crabs in two hours; he believes that these crabs were not here on July 3-4. It’s like, according to his report, they appeared overnight. Something else is changed: the population mix is now very different. Before 1 or 2 females/trip were caught before this new population (according to the comments), but now half large female and half of that is carrying sponge-eggs. He had never seen so many “eggers” before and although he was pleased with the increase in the hard shell male crabs- “jimmies” - almost all of the crabs (except 1) were of legal size. That was a concern because last July 75% of the crabs here were small non legal sized crabs. He returned hundreds of small crabs each trip, today, just 1; this is completely different from last year. These crabs were not here last week according to him.

My trip to Old Saybrook was even more perplexing. Checking a few of the usual productive areas I met with some crabbers, one that I see on a regular basis who called out to me: “Something is happening” as I approached a five gallon pail- “got about 20 in one hour.” This was a surprise as for weeks catches languished about 6 to 12 a trip.

“Take a look,” (which I did), “look closer, see the yellow underneath?” The crabs had a distinctive yellow shade around the mouth area, some more than others but all had it. “Hard shells-- shells hard as a rock. They were not here last Saturday.” The explanation continued that all spring, he had been catching jimmies, large hard shell males, 6 – 7 inches, all big. Shells bright white and clean shells, but these were different, smaller (several 4.5” crabs had been thrown back) hard shells and the yellow color. These crabs are different, they are not like the crabs here before. Did I know why? “Not certain,” I said, “but it did follow a pattern—a large amount of crabs 3 to 4 inch had been reported in Milford, then West Haven, New Haven Harbor started picking up the 3 to 4 inch sizes the third week of June and now Branford, Clinton and Old Saybrook crabbers were both saying something is happening.” “The crabs appear to be moving east,” I replied, “at night.”

We won’t know for certain until the Connecticut River salt water wedge forms. I have been looking at the crabs caught here in central CT since June 10th and they did not have this yellow tinge in the mouth area, also some of the crabs had a mossy brown coloration around the claws.

The high density of 3 to 4 inch crabs in the Milford/Stratford areas could be dispersed by tides, but the reports of sudden appearances of Blue crabs in the east could be tracked. So, if anyone notices a sudden change in male/female population mix or a different female/sponge (eggs) mix of legal size, please let me know. Also be on the lookout for these “yellow” crabs; show a distinctive yellow patch around the mouth area. One crabber said this is common just before the crab sheds its shell.

Again, the concept of large numbers of Blue crabs moving east is not found in any scientific or published reports I have about Long Island Sound, this is new territory so to speak. Extensive podding behavior has been documented for the cold water tolerant spider crab for Long Island Sound (Libinia emarginata) but not to my knowledge for the Blue Crab.

The test case for this podding behavior may in fact be already upon us in the Connecticut River. For several months, the freshwater outflow has been extreme. Any crabs from last year were eliminated by several months of fresh water. According to Jon Morrison of the United States Geological Service, the salt water wedge reached Essex Town Dock on or about July 2nd. The Connecticut River flow is down to about 10,000 cubic feet of fresh water/second. Still sounds like a lot of fresh water but in May/June the flow was enormous. You might want to check out the website that the USGS and Jon established; it’s a great resource for the Connecticut River and it is a format that’s clear and understandable. It is: http://waterdata.usgs.gov/ct/nwis/uv?cb_all_00065_00010_00095_90860_00300_00301_00400_63680_00010_000aa95_90860_00010_00095_90860=on&cb_00065=on&format=gif_default&period=7&site_no=01194750

Blue crabs, if they appear at the Essex Town Dock, got there by swimming up the river, and not from upstream. The dynamics of the Connecticut River might be the test case for the movement of crabs in the east. But, if crabs arrive and they have yellow patches that might be a strong clue.

Western reports continue to speak if a third wave of small crabs a late May/June Megalops hatch. Small crabs less than an inch to one inch across have been observed in Greenwich— by the thousands. A report from the Norwalk area is very similar- many small crabs about an inch across. Catch rates in the west continue to climb ranging to 20 to 40 crabs/hour with 80% still undersize and in one report- 90% undersized. The early reports from some veteran western Blue crabbers were absolutely correct, we are going to have a great year.

Unfortunately the East –to the Rhode Island border remains very quiet. So any eastern reports, even poor ones would help. In the central sections of the Connecticut shoreline, if anyone notices a change in crab appearance, male/female mix or catches crabs with that yellow patch, please let me know. Something is happening in the central sections, we just don’t know for sure what it is yet. One this if for certain, it’s time to break out the crab nets between New Haven and Old Lyme. Thanks so much for all of the observations.

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