From Tim Visel at The Search for Megalops:
ISSP and Capstone Project
The Sound School Regional Vocational Aquaculture Center
The Search for Megalops – Program Report #2
August 4, 2014
“You Do Not Need to Be a Scientist to Report”
- Small crabs increase in central Connecticut
- What About Our Megalops?
- Habitat Changes – Long Term Bottom Conditions Are Key Indicators
Reports continue to come in detailing larger numbers of small crabs in central Connecticut—1 to 2 inch size higher in the marshes and 3 to 4 inch towards higher salinities. Adult crabbing did pick up a bit, then slowed and suspect the first round of shedding is now occurring—look for soft shells and paper shells to increase. The amount of small crabs for some reports mention 5 to 1- some as high as 10 to 1 which are good signs that crabbing will improve in some areas.
High tides are the best and deep holes that held adults over the winter can be the best place to start and some really hard shells (their shells are often muddy – yellow or moss covered but they are packed) are being caught in these areas.
Crabs have shown in Essex, but freshwater flows make catches difficult- hook ups occur but let go when they sense the surface waters? Catches remain slow – the Baldwin Bridge is only at 3 to 4 crabs per hour.
The summer continues to be cool, with colder air pushing for south, only two 90° days so far according to my records and the NAO projections continue to be negative. A negative NAO opens the door so to speak to allow cooler air to sink south into the central US. The storm track also shifts- a negative rating a more coastal track; a positive, a more offshore track. Some of the worst hurricane seasons are associated with the occurrence of negative NAO patterns.
With the temperatures so cool, I doubt if habitat compression will start this summer, there should be enough oxygen in the Sound for most organisms.
I appreciate all the reports,
Small Crabs Increase in Central Connecticut
Around the middle of July came the first reports of small crabs but usually around vegetation or shelly, sandy shores. Some crabbers have reported soft muds over firm bottoms and the winter ice maybe changed the habitat type which small blue crabs prefer. Areas with bivalve shell and patches of eelgrass appear to be the best post Megalops stage areas for blue crabs. However, the reports of mud smelling crabs and crabs covered in mud do lend some questions of Sapropel deposits (see last section) during the winter.
Sandy, shelly areas have the best small crab reports also tidal rivers known to contain natural oyster reefs (beds). It is these areas that small blue crabs can find food and cover from predators. Featureless soft bottoms provide little cover and lower feeding opportunities. Soft mud bottoms usually suffocate shellfish populations and may explain (partially) why some areas that used to contain large populations of small blue crabs last year do not this year. The other explanation is that the winter temperatures killed many blue crabs and mud suffocation maybe one of the possible ways that this occurs. Retired oyster growers would tell me that thick river ice would accelerate outgoing tides under the ice and move huge underwater “mud” deposits from upstream, downstream covering lower river oyster beds, suffocating them. Over the winter sometimes three or four feet of leaves were moved this way.
After severe winters, oysters were “winter killed” and paired “matched” shells of dead oysters were then called “stools.” Areas with soft bottoms that when disturbed emit sulfur “match stick” smells are now suspected as being extremely toxic to young blue crabs (Sapropel toxicity). Look for areas of bivalve shell to contain the most sublegal blue crabs and channel edges or transition areas from deep river bends to hold the most adults.
What About Our Megalops?
After two weeks of no reports regarding small crabs, the first reports mid-July came in from the lower Hammonassett River. Some sightings were also reported in the RT 146 Guilford area, the Branford River and East Rivers. All reports mention an increase of small 1 to 2 inch crabs, although reports of 1 to 2 inch crabs have been also mentioned in the Lower Connecticut River and North Cove, Old Saybrook. Reports of increasing numbers of small crabs are a very good sign. Crabbing generally has been very slow and it seems that in previous great blue years, the numbers of 1 to 2 inch crabs that overwintered along our shore (IMEP #22) and observed in early spring did not occur. A look at the 2011 and 2012 blue crab years show a distinct change and completely agree with Masspi and his report for Massachusetts (July 3, 2014) the same can be said for Connecticut as well.
Our winter last year represented a negative or neutral NAO pattern allowing massive bulges in cold air sinking south while pushing sub-tropical moisture north along our coast- more snow. Since 2008 the NAO has been more and more in the news (especially after NOAA rocked the fishing community linking NAO patterns to the abundance of the American eel in 2008) with its polar vortex, (Megalops Report #1, January 2014) (Megalops Report #2, February 2014) Anyone following the last two winters would agree the numbers of inches of snow and “ice on” days have increased. We might see increasing offshore ocean temperatures pause after these past two winters, but that data has not been available much before May 19 (NOAA Newsroom –SS14.04). The May 19th, 2014 report mentions a shift in average temperature of one month (seasonal) from November 20th to December 20th. If cooler waters prevail we may see a shift back. Many crabbers have commented that the season is “later than usual” and they are absolutely correct.
Shorter lived / high reproductive capacity organisms have long served as the “watchmen of climate change” and one of those (I feel) is the blue crab. It is more difficult to follow changes of long lived species like the Quahog clam (which live to be 80) than short lived species like the blue crab. In our area, the blue crab might not only be an indicator for climate change but important climate patterns (NAO) as well.
It is very responsive to habitat and natural conditions including predator / prey, reproductive capacity, habitat quality and climate temperature / energy factors. This makes short term predicative models for the blue crab almost impossible requiring long term observations (my opinion.). Many biologist and naturalists decades ago urged caution in very short term observations to make long term population estimates or habitat values (Roberts, 1985, Pauly 1995). A few years ago an article titled, “The Blue Crab Conundrum” (Chesapeake Quarterly, Vol. 11, #2, July 2012) authored by Michael W Fincham examined all factors associated with rapid changes in blue crab abundance. It was a good article looking at all the factors and recognized that any one of them could make the difference. One of the indicators is the timing and strength of our Connecticut Megalops set. The set was very “late” last year, so I feel this year perhaps as well. The capacity of blue crab Megalops to survive cold winter is now being researched in other New England states.
There is a growing interest in long term resource surveys when compared to climate, but there is the problem short lived species often provide the poorest short term models. That in part led to my original research question the rise of blue crabs from 1998 to 2008 was steady until the NAO changed. Some great blue crab years and then none was the first blue crab report of fisher observation trends (2010). I follow historical fishing trends and one species that has been an indicator of cold has been the halibut (see Megalops #4, April 25,2014) and latest reports from Maine Working Waterfront News (August 2014) report that halibut are slowly increasing. These colder temperatures might be helping them and lobsters here also.
When I started the newsletter, I did not feel that blue crabs could complete the reproductive cycle here. I feel differently today. The 2008, 2010 blue crab seasons changed my view entirely. However, patterns do emerge; something that has not been discussed enough (my view); it gets colder than warmer and habitats reverse with storms and species abundance directly follows.
Many fishers (including this one) have noticed a dramatic increase in the reproductive capacity of Black Sea Bass (a tasty fish of reefs, rocks and shoals) these past two decades. Its scientific name is Centropristis Striata – it is a type of grouper (serronidare) and can grow up to a 9 pounds / 19 inch fish. They are strong and have sharp gill and dorsal fins and frequent lobster trap visitor when I lobstered with my brother, Raymond off the coast of Madison.
When we first started lobstering in the late 1960s, Tautog (Blackfish) was more numerous and often entered lobster traps to eat our lobsters. By the mid-1980s, Black Sea Bass increased and now has become very prevalent. But this is not always the case.
In the May 30 1884 volume from the United States Commission of Fish and Fisheries, David S. Jordan talks about several dramatic changes in “sea bass” populations (the name has had several changes the past two centuries)
136, The Sea Bass – Serranus atrarius
“Previous to 1878, there were no records, only four instances its occurrence east of Monomoy (Cape Cod) but in summer of 1878, several were taken in (the) Milk Island weir, off Gloucester. There is no reason to believe that fifty years ago (1834) Sea Bass was much less abundant in southern New England than it is now.
In Linsley’s catalog of The Fishes of Connecticut, published in 1842, the species is described as a great novelty. It is curious however, that some time between 1830 and 1840 there were according to Storer, fifty or sixty vessels fishing for sea bass in Vineyard Sound. In 1787, if Schoepf is to be believed, they were rarely seen in the New York market.”
But in 1915, they were in the New York City markets listed as “sea bass.” In 1884, the average size of Sea Bass was one and a half pounds, but later as the warmth increased, Black Sea bass (and also Striped Bass) grew larger. In the 1870s an eight pound Stripped Bass was newspaper article material, one would hardly consider that the same way today.
The reproductive capacity of Black Sea Bass has increased with our most recent warm period 1972 to 2008 – most indices mention the rise, it also occurred during a dramatic downturn in Tautog, also a favorite reef fish. And recall it was black sea bass that was consuming large quantities of blue crabs last fall (Megalops #6, October 24, 2013) as reef dwelling and deep water the Megalops set had occurred in deep bottom waters and fell victim to such “top end” predators – and not the preferred habitat for blue crab Megalops. Most fishers in southern New England I feel will agree that Black Sea Bass has become at times more abundant that Tautog – they have reversed in abundance since the 1950s.
Habitat Changes Long Term Bottom Conditions Are Keys Indicators
Several crabbers have commented upon the impacts of tropical storms and hurricanes recently on blue crab habitats and looking into the historical references, two basic conditions occur. I agree that both “energy” and temperature can and do have substantial habitat impacts.
- The Deposition of organic matter from watersheds (leaves) may have delivered a huge amount of leaf rot into the lower western Connecticut Rivers. The Saugatuck River especially appears to have been most impacted. Leaves decay in high heat reducing to toxic sulfur compounds toxic to most marine life. See footnote #1.
- The high heat in 2011 and 2012 while not having a direct impact upon adults - they were able to get into more oxygen sufficient areas as reported by several 2011 observations. Post Megalops stages may have been killed by this high heat and sulfur reduction process. This could explain the inshore waves of crabs migrating east in 2011 perhaps toward cooler eastern waters.
- Tropical storm energy (and tides) has a tendency to sweep Megalops from estuarine areas out to sea. This is frequently mentioned in the Chesapeake Bay historical literature.
- Tropical storms’ rainfalls can cause salinity “shock” mortality – sudden changes in salinity are often deadly, especially in warm water (Megalops report #12 August 2, 2011).The pattern here has abruptly shifted from very hot (which may have been too hot for Megalops) to cool which may have delayed the set so late in the fall that they didn’t have a chance to survive the brutal winter – winter kill is also a term often found in historical literature.
- Tropical storms, even Nor’easters, can remove eelgrass meadows, a key habitat type for the Megalops and star crab sizes. The amount of submerged aquatic vegetation (SAV) can lead to a “habitat bottleneck” and an increase of predation – no cover. A key measure is bottom oxygen levels – extended periods of high heat can be as dangerous as extended periods of very cold. In high heat eelgrass “wastes away” from disease. In cold, strong storms rip it up. What appear to be the best habitat conditions are cold to warm (transition) with little in the way of strong storms.Footnote #1“This putrefied organic matter is a Sapropel and as these organic deposits “age” they become more toxic to marine life.It is organic Sapropel that is linked to the high heat black water fish kills of the last century. Organic matter when trapped in sluggish coves or blocked by manmade dams collects in high heat. This Sapropel then releases hydrogen sulfide into the water with its toxic impacts. Bacterial breakdown of this bottom organic matter converts to a slower sulfur cycle of bacteria that live in the absence of oxygen. Although marine compost (mostly leaves and dead shore grasses) has been used as a fertilizer for centuries (mussel mud), Connecticut farmers discovered the dangers of using old Sapropel that underwent sulfur reduction behind dams. It is in this area that toxic Sapropel formed with its characteristic pungent sulfur smell. This is an excerpt from the Connecticut Board of Agriculture 1879-80 that provides the account of Mr. J. I. Stevens of Essex, CT on page 49 of the 2nd report of the Connecticut Agriculture Experiment Station, 1879 which perfectly describes Sapropel toxicity. The river mentioned in the report is the Falls River which runs from Ivoryton to Centerville sections of Essex today.Mr. Stevens then as most commercial fertilizer producers were “invited” to provide samples to the experimental station for analysis contained sulfuric acid and notes in a letter the sample should have been from the middle of the cove (North Cove Essex – not the upper section). One source although had already been found to be toxic the organic debris trapped behind mill ponds (Falls River)“Our mill ponds a few miles back from the river contain a rich, black mud, quite deep and with a very strong smell. It has been tried on various craps but kills everything – after being hauled and dried it turns from black to white, and puckers the mouth like alum.” The experiment station then adds “the astringency here referred to Mr. Steven’s letter is due to soluble salts of iron or alumina. Composting with a small proportion of slacked lime will decompose these salts and render the black mud a safe and serviceable application.” The description by the Experiment Station in 1880 fits the one provided Dr. Donald Rhoads of Yale in 1985.”In one of the first comprehensive Long Island Sound Environmental workshops – sponsored by the NOAA Estuarine Programs Office and US Environmental Protection Agency EPA (US Dept of Commerce 14th and Constitution Avenue May 10, 1985 – Battelle Contract E68-03-3319 and was published 1//15/1986. The subject of bottom sediments and oxygen depletion were discussed, one presenter Dr. Donald Rhoads of the Dept of Geology and Geophysics of Yale University reviews this topic on pages 47 to 57. Dr. Rhoads mentions the need to study the role of sediments in low oxygen conditions and Long Island Sounds organic matter loadings. In his summary on page 56 Dr Rhodes asks what the distribution of Sapropels is. What are the distributions of the biological storage system low sulfide and purging systems high sulfide? The write up at the end of the report includes a question and answer session in which Sapropels are highlighted many times and included as a critical study area.“Underlying the dysaerobic and anaerobic water one typically finds organic rich black (i.e. sulfidic) muds that are termed Sapropels. These are rich in iron monsulfides; the physical properties of these muds are distinctive and the best description that I have heard of them is that they are like a “black mayonnaise.” Dr. Donald Rhoads workshop participant, May 10, 1985.Sapropel toxicity is a huge area of marine habitat change and the negative impact of sulfur rich sapropel is just now being reviewed. Dredging and composting Sapropel deposits is the only long term solution. Some dams in Connecticut have tens of feet of decaying leaves behind them – and in high heat Sapropel forms which is deadly to most marine life. In times of heavy rains or floods, huge quantities of Sapropel are washed downstream. This is what I believe happened in some areas of western Connecticut in 2011. “The first direct use of Sapropel used as a fertilizer I observed was on Cape Cod. It was mixed with old oyster shell and used to nourish a tomato patch owned by John Hammond. It was Mr. Hammond who called it nature’s “first fertilizer,” but because of its acid / sulfur makeup, excellent for tomatoes.”I am going back to my former fisheries teacher at the University of Rhode Island, Bernard Skud, and a statement made in class over three decades ago “it’s not the ducks but the duck habitat that determines populations.” Bernard Skud was a former U.S. Fish and Wildlife Service regional director and very familiar with the “duck stamp” -a partnership to conserve the habitat important to migrating duck populations and hunters. These habitat discussions always left an interest and a question about sub-tidal habitats and the long term impacts of habitat reversal mentioned so many times in the fisheries historical literature. For blue crabs, eelgrass habitats seem to be critical second only to estuarine shell. Post Megalops stages during times of constant storms and habitat instability are periods that show the lowest catch landings.New England it seems has had four such recent habitat reversals; about one complete reversal about every century. I look at catches of fish for links to habitat conditions. For example, in 1842 the capture of a Black Sea Bass was considered a unique and rare catch, or in terms of language at the time “on oddity.” That would hardly fit today’s Black Sea Bass population – the reproductive capacity of the Black Sea Bass in this latest period of heat has soared here – no one would consider catching Black Sea Bass today as “odd,” but at one time people here did an excerpt from the U.S. Fish Commission 1884 details these changes, but were not climate questions but one’s related to catches.The cold reversals are roughly detailed as 1650 (early settlers picked a very cold time for our shores) 1770, 1850-1880. The negative NAO cold period of 1950 to 1972 is not included in many historical records because it is still “young” as compared to the others. Warm periods follow the cold and last about 4-5 decades. For Long Island Sound have good information for the cold 1850-1880 period “Devil’s Belt” and the 1880-1920 period of great heat that followed. Some reversals have transitions – great cold and heat as weather patterns conflict as a type of battle to what will eventually win out. It is now suspected that scores of estuarine coves and bays over recent geological time will produce increases in oysters following each warm period; blue crabs and soft shell clams also in heat. In periods of cold, bay scallops, lobsters and the hard shell clam (Quahog) will do better.This appears consistent with fish landing records over the past 150 years. The problem is of course that these trends are longer than our life spans, giving the family fishing journals of the last century the advantage of defining cycles. The oral history of fishing cycles is one that can be found in most fishing communities and helps explain the firm belief in them that fish populations appear to come and go in long patterns and when you examine climate records, fish landing records and habitat descriptions you see this pattern also; they do reverse.*see The Embryology of the Sea Bass (Serranus Atrarius) by Henry Wilson, Assistant - U.S. Fish Commission (1884), pg. 209. Local names include “Blackfish – Blackwill, Black Harry and Hannahills.”For blue crabbers wishing to read more about the eelgrass/ Sapropel habitat see IMEP habitat newsletter #13, March 2014 “Did Eelgrass Help the Rise of Blue Crabs 1998-2012” on the Blue Crab Forum™ ‘s fishing, eeling, oystering thread.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 email@example.comThe Sound School is a Regional High School Agriculture Science and Technology Center enrolling students from 23 participating Connecticut communities.The latest Search for Megalops (BlueChip) newsletters can be found on The International Blue Crab Blog Spot™, The Blue Crab Info forum™ (Northeast Crab Resources) and Connecticut Fish Talk™ Salt Water Reports.Email your blue crab reports to: firstname.lastname@example.orgIf interested in helping with the Blue Crab Census, please email me at email@example.com and register as a volunteer.Tim Visel
The Sound School