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PostPosted: Thu Nov 30, 2017 12:27 pm    Post subject: Megalops #5 - End of Summer Report - 2017 - Tim Visel Reply with quote

The Search for Megalops
“You Do Not Need To Be a Scientist To Report”
Megalops Report #5 -October 5, 2017
View all Megalops, Environment Conservation and Habitat History Posts on The Blue Crab Forum™
Tim Visel, The Sound School, New Haven, CT 06519
Delayed Report

• September Crabbing Improves in the Connecticut River
• Still No Megalops Set
• Salt Ponds, Rivers, Lagoons and The Blue Crab
• Rusty Crabs Dominate Catches
September Crabbing Improves in the Connecticut River
Although our dry summer was a concern for the farm community, a long dry spell allowed blue crabs to move far into the Connecticut River. By September 1st, they were up to Brockway Island and a week later, to Chester, CT.
For the period August 10 to September 10, crabs moved into the shallows from deeper holes and into the range of shore handliners. Catches improved to 4 to 6 crabs/hour. Earlier in the summer, crabbers who fished from boats had a decided advantage, but that changed around Labor Day. Good crabbing was observed adjacent to Brockway Island and crabs must have entered Hamburg Cove as well in early September. The Connecticut River trappers (they have multiple pots with small floats) headed to Nott Island Bay and found the crabs in six feet of water – mostly rusty crabs – later catches were almost to Chester in deep areas. Crabbing improved at Essex, the 10th of September to 4 crabs/hour. Central CT crabbing has remained slow and for many who crabbed, caught only a few. Tides were important as well; 2 hours before or 2 hours after high tide seemed to be the best. The fall migration is underway now and crabs are heading to more saline areas; some night time catches have approached 10 crabs/hour – a large difference from early spring.
See you at the docks – Blue Chip
Still No Megalops Set
These still do not appear to be a statewide Megalops set- what does seem to be happening is like salt ponds on Cape Cod; some areas continue to hold some Megalops as habitat refuges. These areas that can hold crabs – and Megalops – these are compressed habitats as they fulfill all life stages. These pockets of habitats hold the last dense blue crab populations, and at times crabbing in or near them can be very good.
We got a glimpse of how this occurs last year, in Goshen Salt Pond in Harkness State Park, in Waterford, CT, as thousands of blue crabs that were trapped left after a small breach occurred (Nov, 2016), and many studies on Cape Cod (one by William Wilcox in 2004 and Martha’s Vineyard describes Megalops thought to be from the Chesapeake Bay region being swept into salt ponds and sealed in them. Salt ponds and coves close to saline waters can hold Megalops and thus at times, provide “Islands” of dense crabs. The South Cove, North Cove situation is a classic example. North Cove, Old Saybrook was dredged in the middle 1950s as a Federal Harbor of Refuge -as many areas were- in the 1950s and 1960s. The number of stronger storms and the increase in boating created federal legislation to provide these free emergency storm shelters. The Lower East River in Guilford, CT is a frequent example of this Harbor of Refuge legislation and written up for a conference at Hofstra University and printed in the Journal of Shellfish Research. (See An Oyster Bed Restoration Program for the East River, Town of Guilford, CT 1988 – Visel, T.C. 1988 Mitigation of Dredging Impacts To Oyster Populations, Journal of Shellfish Research 7.267-270).
North Cove dredging resulted in deepening this shallow cove which perhaps contained a brush weir created by small stones (reports of the initial dredging project being slowed by the removal of thousands of small stones). South Cove however was not dredged and the remains of a stone fish weir, a stonewall hook remains of a Native American fish trap. South Cove has not been dredged. (See “Evidence of Native American Brush Fish Weirs in South Cove, Old Saybrook,” Timothy and Abigail Visel, Aquaculture Ecology and Current Research Archaeological Society of Connecticut, October 18, 2008, The Fairfield Museum) and does not contain a deep saline “hole”.
The North Cove dredging project created a deep saline pocket in which blue crabs can now hibernate – saline but yet absent the serious salt water predators including the conch and starfish.
The differences in blue crabbing can easily be seen today, the dredging of North Cove created ideal habitats for the blue crab, a deep pocket of saline water with a black sticky, sapropel deposit that crabs could hibernate in (winter). In the summer, the dredged area now allows a greater residence time for fish and shellfish larval forms; it is rich in killies, silversides and at times snapper blues- all feeding opportunities for the blue crab, both juveniles and adults. The dredging project in effect created an idea/habitat for the blue crab and last year, I saw hundreds of small blue crabs there. North Cove has become one of the Old Saybrook’s most popular Blue Crab spot. The dredged area also allows menhaden to school and escape the bright sun. Bluefish and stripers are often are caught here (personal experiences included) and frequent the dredged area. I have tried South Cove several times with no such luck – it is shallow energy restricted by a road causeway and subject to the buildup of ice in winter.
Did dredging help (the fishing and crabbing) in North Cove? In my opinion, it did, and created a chance for sapropel to form – a black stick compost (mud) that crabs hibernate in. It is a balance in heat versus cold that sapropel can turn deadly; the sulfur smells of sulfate metabolism the source of “marsh stinks” in late summer. In colder water, sapropel is fine, oxygen penetration is higher and many life forms live in the “live mud” described in the fisheries literature. However, in extreme heat and cold sapropel now becomes more of a foe than friend. It is the source of sulfide winter kills if too cold and the toxic ammonia discharges if too warm (hot).
I want to thank all these Megalops reporters who continue to report their habitat observations and catches as we learn more about the blue crab in Southern New England. Signs of a widespread Megalops set even if it is late this fall, is significant.
Salt Ponds, Rivers, Lagoons and the Blue Crab
It is the shallow waters that would show the first signs of a regional habitat reversal. The impacts of energy and temperature had been a habitat history lesson for those who lived next to salt ponds for centuries. In storm events, such salt ponds were often blocked – small inlets that were easily closed by strong storms. In time, the waters would turn black and smell of sulfide as “black water” and dead fish smells soon permeated the area. Dozens of similar reports of which can be found in the fisheries historical literature. Salt ponds which allowed continuous and strong flows of the tide seemed to have none of these black waters and efforts included to stabilize them or unblock them to restore tidal flows is found in historical fisheries literature. The colonial alewife fishery is filled with references of unblocking runs filled with leaves and trees blown over after floods. This goes back to the 1790s. And, what makes them so valuable, the spring melted snow and herrings they occurred after the ice, before spring crops matured, and they came to you literally at your door. Salted, smoked or at times pickled – was rich in calories and for several hundred years a snack food (salted “alewife”).
Alewife needed energy melt water flows and low temperatures for stream habitats to remain clean and oxygen saturation levels to be high. Cooler water has more oxygen (atoms fit better) and pressure also allows a liter of cold water to hold more oxygen than warm. (Think of stacking cubes rather than balls). Colder water is denser and acts to keep higher oxygen levels in the shallows such as river lagoons (drowned river mouths) keeping barrier spits “open”. Some river lagoons have a barrier spit – such as the mouth of the Hammonasset River – (called the Dardanelles in Clinton) or the famous Niantic River “Bar” (now stabilized and contains both rail and road causeways). During cold and energy filled periods, these barrier beaches or spits can break, allowing more energy into the lagoon. These episodes frequently have a layer of sand and bivalve shell (shellfish sets) between the warmer and less energy periods the formation of Sapropel (black mayonnaise). These cores often contain a habitat history (Niantic River Bar was last breached in 1815). It is these cycles that change the temperature and chemical characteristics of sapropel, the remains of plant tissue (mostly fall leaves) that builds in layers over “previous bottoms.”
The formation of the first marine experiment station in Rhode Island, on Great Salt Pond (Pt. Judith Pond) in 1898 was because of a huge “black water” Fishkill in 1897. Local fishers had noticed the inlet to Point Judith pond had closed and efforts to redirect (open) it with oxen teams had failed. Dr. George Field and local Narragansett fishers pleaded for a permanent breach way to allow the tides in and out. But, with a permanent opening came chemical and biological changes in the habitat themselves. More salt water meant more salt water predators, more energy increased catches of striped bass, but also allowed starfish to enter and consume shellfish. In the 1960s, the Waterford East Lyme Shellfish Commission would trap starfish that would feast on bay scallops in the Niantic River
At first, the local Pt. Judith Pond Rhode Island oysters rebounded after the breaching, as the sapropel melted away, but more saltwater then subjected oyster beds to the impacts of drills and starfish. Inlets that were breached tended to direct storm energy and move sand bars (sand waves) into them and then move them shoreward. That is the habitat history of Alewife Cove between Waterford and the City of New London. In 1985-86 Alewife Cove had a sand wave that made it all the way inland to Highland Avenue. (Personal observations of the Alewife Cove Watcher program for Winter Flounder.) In 1988, Alewife Cove was dredged to remove these sand bars in the hope of restoring tidal exchange (flows). They have reportedly returned.
Toms Creek at the westerly edge of Hammonasset Beach was dredged in 2014 to remove a sand bar which threatened to block the entire creek after Irene and Sandy. Salt ponds once sealed could hold organisms in, or hold them long enough to grow.
The warm reduced flushing in salt ponds would in fact hold blue crab Megalops in- they had little or no chance of escape and as long as it was “warm” and not hot, blue crabs could dig into Sapropel and winter over. (Some large crabs this spring in the Old Saybrook area had sapropel – black stains on them.) Blue crabs can live in or near sapropel if waters contain enough oxygen.
Lobsters in colder higher oxygen waters can also make peat and sapropel their homes. In heat, the sapropel now becomes deadly and hosts bacteria that eat their shells, the vibrios. However, cold temperature that allows oxygen requiring bacteria to thrive, not vibrio, and as long as it was cold lobster shall disease was rare, but not so in heat. That heat or cold can happen as habitat compression. The natural history of the American Lobster Bulletin of the Bureau of Fisheries Vol. 29, 1909 document No. 747, Issued July 13, 1911 – Francis Hobart Herrick, Professor of Biology, Western Reserve University (The Western Reserve was once part of Connecticut). Cleveland, Ohio, gives an insight into habitat compression.
Speaking about habitat compression in the lobster fishery, termed “as a period of real decline through often interpreted as one of increasing and fluctuating yield and rapid extension of areas fished” as habitat expansion (pg. 171). As habitat compression occurs, catches (yields) of a particular species can increase in them.
In habitat compression good catches can be made in the habitat refugia area (this is apparently what happened to the Passenger Pigeon – a period of heat had compressed populations into an 40 mile long by three to 10 miles wide of Michigan’s upper Peninsula in 1878. Near Petoskey Michigan, hunting here was intense – you could kill hundreds per day – to hunter’s here the numbers were never better – to areas that once contained passenger pigeons, the hunting was terrible. By 1886, the last habitat refugia recorded only 8 by2 miles wide near Lake City, Missaukee County. In 1898, Michigan outlawed hunting from them, but by then, it was too late, the species would become extinct in 1914.
On page 183, Herrick describes Sapropel (although the term was just developed by Kolkwitz and Marsson in 1909) in areas that lobsters were forced to over winter in Maine’s lobster pounds. Here winter sulfides increased in sapropel seeping up from below the oxygen layer especially under ice if long enough.
Lobsters would also burrow into sapropel at the river mouths (as occurred here in the mouth of Saugatuck River in the middle 1980s) and Herrick again provides evidence of sulfide winter kill over a century ago, on pg. 183.
“Lobsters which pass the winter in relatively shallow water often seek protection by burrowing in the muds as usually happens when they are confined in pounds. In such cases, a long period of severe cold may prove fatal (suspected sulfide winter kill – T. Visel). On March 10, 1882, a number of lobsters were taken through the ice by the scoop of a mud-digging machine (sapropel soil harvester – T. Visel) off the coast of Prince Edward Island (An excellent history of sapropel harvesting is now on the Internet – here farmers sought out “mussel mud” (See Drawing Lines in The Ice by Josh Mac Fadyen, 2013) The excrement of mussels, (most likely also oysters) and organic was harvested to nourish nutrient and organic matter poor agricultural soils. Deposits with oyster/mussel shell was very desirable as these shells helped offset sulfuric acid formation when sapropel was again exposed to air (oxygen). New England experiment stations urged farmers to add lime or shell lobster/oyster –to offset at time hurtful acidity from dredged sapropel once applied on land. “They were said to be sluggish but not torpid.” Herrick also reports some of the negative aspects of possible vibrio problem of shell disease of the blue crab on page 192.
“Malord speaks of meeting with cases of melonism ( shell rot/T. Visel in crabs where in consequence of a lesion of the skin the animal becomes entirely black.”
That describes possible vibrio shell disease in heat – from various sulfate reducing bacteria. Blue crabs living in the bays and coves need the muddy/sandy bottoms to hibernate – the can have black stains in low oxygen areas or those in deep sapropel. Those overwintering in sandy soils or those mixed with oxygen and organic tannin will be brown (rusty). As it takes about two years to develop the brown stain, these crabs are usually very hard shells and like older lobsters, shed their shells less often. This is what I observed in 2011 when huge numbers of yellow face and rusty crabs left the Housatonic River. In catch pails, the new shed white belly crabs were no match for those rock hard blue crabs and could quickly kill new shell blue crabs (see Special Report to Megalops Reporters issued August 23, 2012) with their claws in just a few seconds. I had seen similar impacts while lobstering in 1967 to 1981 – new shell and hard shell lobsters – the new shell lobsters rarely defeated a hardshell and banding claws not only reduced mortality at times but saved many new shells. The ease with these yellow face and rusty crabs could kill each other lead to digging out my old lobster bander which my son Willard put to good use – with lobster bands holding claws to the shell.
But it takes time to band claws to the shell (they no longer can fight but still can pinch), but it saved many crabs in heat that would have spoiled.
Most of the blue crabs that leave our rivers seeking eelgrass or deeper waters to hibernate never come back- the saltwater predation and lack of cover is devastating (great for sea bass, tautog and stripers)and late fall catches by John Walston on an eastern rig trawler out of Guilford, CT (1960s) of winter flounder, always had a few bushels of large jimmies that confirmed the fate of many blue crabs.. I asked one day about “winter” flounder next to “summer” blue crabs and he described Connecticut’s “blue crab grave yard” an area between Kimberly Reef and Faulkner’s Island, as a good winter flounder otter trawl tow, but blue crabs tried to hibernate there and now subject to predation by starfish and tautog. He suspected few made it to the spring.
So salt ponds and dredged areas provide a saline environment that at low tide with fresh water, keeps starfish away – perfect for blue crabs. That is why areas such as North Cove, Old Saybrook and the Black Hall River in Old Lyme, obtain the Connecticut River crabs that make the “correct” choice – instead of entering the Sound, they frequently overwinter here. In fact, these areas in deep water remain above 47 ° F and blue crabs were feeding on chunk bunker bait well into December last year. Even in the 1950s and 1960s when blue crab populations in Southern New England crashed, good crab catches could still happen in the salt ponds. Blue crabs did not entirely “leave” here, but were compressed into the few remaining pockets of suitable habitat.
2017 Blue Crab Season is one in which you had to find the crabs; for most crabbers, they did not find you. Because of a very cool spring, the “July crabs” arrived in September about 40 days later than 2013 and a huge 90 days later than in 2012. Our waters are cooling from the 1990s positive NAO today which has more a negative NAO phase, in the middle of such reversals, cooler water allows menhaden to live in the shallows, and the amount of peanut bunker is on the rise – in fact, menhaden levels are now very high. Species (if the springs remain colder) will reverse again over time.
That is why blue crab catches, water temperature data and Megalops surveys are so important. Every observation helps us understand the largest Southern New England Blue Crab population change here in a century.
I appreciate all blue crab observations.
Please send all observations to: tim.visel@new-haven.k12.ct.us
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