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BlueChip



Joined: 29 Jun 2011
Posts: 177
Location: New Haven/Madison/Essex

PostPosted: Wed Apr 27, 2016 10:28 am    Post subject: A Mild Winter - Few Winter Kill Reports - 4/15/16 Megalops 2 Reply with quote

The Sound School Regional Vocational Aquaculture Center
The Search for Megalops Special Report #2
“You do not need to be a scientist to Report”

A Mild Winter - Few Winter Kill Reports
Timothy C. Visel, April 15, 2016


• Blue Crabs moving in Deep Water Eastern Long Island Sound
• Winter Mortality – much reduced to warmer temperatures
• Ocean Female Crabs – A Possibility?
• Small Blue Crabs in shallows and rivers
• Herring Shad and Menhaden enter CT Harbors in large schools

Although the spring is off to a slow start the absence of very cold temperatures has been a relief to many Connecticut Blue Crabbers. I do not expect the winter (sulfide) kills to happen at all. Last spring, terrapins, blue crabs and even conch at times where observed to perish in Sapropel deposits. This marine “living compost” can purge sulfides in very cold water temperatures especially those estuaries covered by ice.

These sulfides can at times reach toxic levels during very cold long winters and become lethal to those who hibernate in organic compost termed Sapropel. This winter hibernation (winter kill) is not expected to occur this year.

The winter resembled at times last years a very warm fall, a strong subtropical jet that brought several “warm” Hudson Valley low pressure systems to be broken by periodic polar Vortex – The Northeast Atlantic Oscillation was in a positive phase – warmer and heavy rains. It seemed for a time we would escape the serious cold air at all – we got it but it did not greatly cool Long Island Sound.

In fact, the early warm winter kept Long Island Sound Seawater temperatures in the 40s all winter and oxygen saturation over 10 milligrams per liter. Very high oxygen saturation and mild temperatures may be part of a surprising appearance of herring – second week of February and mehaden in March and now reports of small shad in the Pawcatuck River in Stonington (unconfirmed).

In the New Haven Harbor – first herring appeared and now menhaden schools are found in the harbor especially at the junction of the Mill and Quinnipiac Rivers. These large schools have attracted many shore birds and even bald eagles feasting on these calorie rich bait fish – here at City Point. Menhaden were reported in the Westbrook area in March and additional schools off Branford Harbor – about 15 days ago.

Look for bait fish schools to leave the warmer Harbor water areas in a few more days. Associated with these early bait schools are now growing numbers of stripped bass.

Ocean Female Crabs?

One of the things we can observe this crab season is the occurrence of very old female hard shells those that appear in the historic literature as sea run or ocean crabs. They are suspected of over wintering in the southern reaches of rivers and these females may present a noticeable barnacle set on their shells.

Female blue crabs seek higher salinity areas to release their eggs and move or migrate to “ocean” waters. An early blue crab researcher Reginald Truitt wrote about these “ocean” crabs in the 1930s. Before the concept of tags researchers relied upon shell appearance as evidence of Blue Crab’s age – especially with the female blue crabs. It is thought that very cold and stormy periods could eliminate much of this female population – they would leave the protection of the “Bay” and now subject to the energy and temperature condition of “Ocean” waters. In warmer periods they could survive for many years and thus appear “older.” Some of the first crabs caught in Connecticut this year may contain some of these “ocean” older females. If you catch a female that might be a part of this population please send me a quick email. Location is important as I believe many blue crabs now hibernate in dredged channels and the mouths of some tidal rivers.

What to look for -

In a 1945 report of the Commission of Fisheries for Virginia mentions a mild winter proceeded the appearance of ocean crabs. (From the 1944-1945 Report of the Virginia Fisheries Laboratory – Commission of Fisheries of Virginia June 30th 1944 to June 30th 1945. “In 1945, presumably because of the unusually warm weather, in early spring, sponge crabs occurred at Hampton as early as April 9th.

Sample of the so called “sea run” or school crabs, which crowded the Lynn Haven region from July 23 to June 30, 1944 were examined. These crabs were covered with a heavy growth of sponges, moss animals, barnacles, tube worms and mussels and had small pink goose barnacles in the gills. Most had exhausted (spawned out) ovaries but some were capable of spawning again. The type of growth on these crabs indicates that they probably did come from the ocean. However it is possible that they were bay crabs which had gone to sea and returned.”

If females survived the winter they may look similar to those reported in the historic literature – such as this one from 1945.


Some Blue Crabs movements reported -

A few reports in central and eastern CT mention large blue crabs in lobster pots. With bottom water temperature holding at 48F look for crab movements towards the shallows. A few observations in tidal rivers mention large blue crabs very active, so some feeding may already be occurring now. Two reports mention small blue crabs in the shallows, Guilford and Bridgeport. This is very encouraging as these 1 to 2 inch crabs could reach legal size if waters warm now into the 60s before June 1st.

We will know by July 1st if any Megalops set from last fall made it. The Blue Crab Megalops can hibernate itself postponing larval development for up to 150 days. If they did survive look for large, numbers of small Blue Crabs by July 15th. In general for the warm waters species a “hold” on declining habitat quality – for cold water species (winter flounder and tautog) neutral – a cooler oxygen rich Long Island Sound has been a boom for the herring group. Baring any severe cold snaps or powerful Northeasters look for an earlier and stronger Alewife return this season.

With the Connecticut Blue Crab season just a few days away it looks like CT blue crabbers will see some.

Thank you again for all the positive comments last year, everyone have a great and safe Blue Crab season.

All Blue Crab observations are important – thank you for sending them.

I respond to all emails at tim.visel@new-haven.k12.ct.us

See you at the Docks.

Blue Chip.


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