Tuesday, October 13, 2015

Blue Crab Blog Reaches 100,000 Page Views

I want to take a moment to thank you, the readers for your continued interest in this blog. The site crossed the 100,000 page view benchmark over the weekend!

Photo Essay on the Chesapeake Blue Crab Industry

Blue crabs and the watermen who fish for them are icons of the Chesapeake Bay. Check out the great photos and story about the challenges faced by the fishery in the photo essay posted today by Reuters. It highlights some of the work my lab is doing to understand the movements and migrations of crabs.

Friday, September 4, 2015

New Study Shows Female Blue Crabs Spawn in the Ocean in Southeast US

Long thought to spawn at the mouths of bays and rivers, we're now finding out that blue crabs spawn in the ocean in some places. My latest research, highlighted in Coastal and Estuarine Science News,  shows that many or even most female blue crabs spawn in oceans waters in the Southeast US. Off the coasts of Georgia and South Carolina, female sponge crabs like the ones in the photo are found at least as far as 8 nautical miles from shore. Other researchers in Louisiana have found female blue crabs even further from shore (read more here).

Why are they going to the ocean to spawn? It's most likely that they are just looking for the salty water (salinity >25) that their larvae need to survive and grow during the first month or two of life. In places like Chesapeake Bay and Delaware Bay, these salty conditions occur within the bay mouth. In much of the Southeast US and Gulf Coast, the same conditions occur mainly in the coastal ocean.

We've known for some time that blue crab larvae spend part of their first months in the ocean where temperature and salinity are relatively constant. Now that we know there are important spawning grounds in the ocean, we need to take a closer look at how many females are there and what they are doing.

The new study also notes a substantial decline in abundance of females in offshore areas since at least 1986. Understanding what this means will be important for ensuring sustainable crab fisheries throughout the Southeast US.

Here's a link to the scientific paper in Estuaries and Coasts.

Thursday, August 27, 2015

$5 or $50 Reward for Tagged Crabs in Chesapeake Bay

If you crab in Chesapeake Bay this summer or fall you might run across a crab with a pink or white tag like the ones pictured here. Reporting them is worth $5 or $50 for each tag. My lab at the Smithsonian Environmental Research Center in Edgewater, MD has tagged nearly 15,000 crabs since June 2014 and 1 out of every 20 is worth $50. If you catch a tagged crab, please help our study by recording the information requested on the back of the tag and calling the number or visiting the website listed on the front the tag.

The tags are on both male and female crabs. Tagged crabs have been released at sites throughout Maryland and Virginia. We've had a lot reported already but we know there are quite a few more out there. We've even had a couple that were caught as far away as North Carolina.

If you've already reported but haven't heard back from us, please be patient. We're working as fast as we can but a hundred or more reports each week it's hard to keep up.

Tuesday, July 21, 2015

2015 Connecticut Blue Crab Report #4

From Tim Visel at The Search for Megalops:

The Search for Megalops – Report #4 – July 20, 2015
Small Blue Crabs Surge in Central CT
The Sound School Regional Vocational Aquaculture Center
Inter-District Marine Education Programs
Capstone Project ISSP Blue Crab Monitors
Blue Crab Research in Long Island Sound 2015
You Do Not Need to Be a Scientist to Report
July 20, 2015
Tim Visel

Follow Megalops reports on the Blue Crab Info™ Northeast Crabbing Resources. IMEP fish habitat reports can also be found on the Blue Crab Forum’s™ “fishing, eeling and oystering” thread. Thanks also to Connecticut Fish Talk ™ for including Megalops Reports under the Saltwater Reports thread and the Blue Crab Blogspot™, Dr. Matt Ogburn, for posting all Megalops Reports.

·         Small Crabs Surge in Central CT
·         Megalops set uncertain
·         Are high blue crab catches sustainable
·         Eelgrass and Sapropel cycles
Small Crabs Surge in Central CT
“Don’t put the crab nets away yet” was a response from a veteran Megalops reporter – just a few days after the June 15th report thousands of 3 inch crabs showed along central CT, the usual good spots – CT River to West Haven in general,  but very dense populations of 2 to 3 inch crabs were reported in the Clinton Harbor/Indian River area (multiple reports) Branford River and Gulf Pond in Milford.  Some eastern CT coves have reported some adult survivors – Alewife and Jordan coves.  Adult crabs however remain scarce; one crabbing family I spoke with who visits Connecticut from South Carolina to crab here reported 2 crabs from the Oyster River (Old Saybrook).  Last year same day on afternoon of June 27th 2014 crabbing yielded 26 crabs but they had a great day crabbing regardless.  He surmised the waters were still too cool and he felt the run was a month off, I agreed it was a cold winter and cool spring-- a month off was generous.  I feel for some species, it is 6 weeks. A cold summer is come to define the first few weeks, it seems as though spring continues.  A recent conversation with a Baldwin Bridge DEEP fishing pier blue crabber (Old Saybrook side) July 13 was trying it again the previous week: July 6th yielded not one crab. The pier had no crabbers at high tide, he was alone.
However some of the first run descriptions come from Clinton Harbor – 20 to 1 in other words twenty small crabs are observed or caught to one legal crab.  Branford River (by the high school) 10 to 1 and Oyster River Old Saybrook about the same (when rates for legal crabs are above 2-3 crabs an hour.)

Gulf Pond in Milford with North Cove, Old Saybrook—all report small crab sightings but no large catches as late.  The Western CT Rivers and Western CT areas remain in general very “quiet.”  The CT River Fishery is also slow – a good number of 3 inch crabs at the mouth indicates the fall 2014, Megalops set or some of the 2013 set at least in some areas made it over the winter in the marshes.  A second wave of crabs would be a good sign (see following section).  In 2011 three distinct waves of small crabs were identified (see Megalops Report July 11, 2011) and built into an amazing CT River fishery – 60 to 80 crabs/hour (four lines) which was interrupted by Hurricane Irene on August 27th to August 29th.

A second Megalops wave now would make it to legal size by September 15th in time for a fall fishing but what would be needed is warmth and little storm activity.  The good news is we have some crabs that will shed into legal size over the summer – many crabbers are hoping for a better fall fishery.  
See you at the docks.
Blue Chip
Megalops Set Uncertain

One of the ways that habitat transitions can be measured is the strength of reproductive success. That is usually described as a species range. The range varies of course to habitat parameters and the recent warm period most likely shifted the Blue Crab range far into northern waters.  It had been there before a century ago and the recent cool down and increase in storm intensity may destroy blue crab Megalops in a variety of ways but that needs observations over a long period of time to confirm any changes. We may have already seen that happen in the Hudson River blue crab populations. As our hot and relatively dry period extended into the 1990s, fresh water river flows declined; salt water tidal wedges even at times eliminated it; that also happened here during heat and dry summers, blue crabs were observed in Deep River, even Chester (Megalops Special Report, September 27, 2012); the salt wedge was strong. These hot days and springs seemed to favor our blue crabs while harming alewife returns in streams most impacted by warm storm water. When you look at anadromous fish returns in the 1950s and 1960s, they were good years. The American Shad peak year is 1958 and not so great for the blue crab. Changes in rainfall storm intensity even prevailing winds can alter a blue crab Megalops set, but increases here were gradual, all starting it seems in 1998.  It is not any given year, but a series of years which could be called a trend. Between 1998 and 2008, blue crab populations in Southern New England tended to increase and then explode in 2010 leveling to 2012 and now after its best year, apparently failing. Colder winter temperatures is the latest factor to be reviewed but I feel it is many factors - cooler temperature, increased storm intensity and frequency, rainfall (salinity shock) may all combine to reduce the Megalops set and eventually the range of blue crabs.


The past three winters may soon cause a pause in the blue crab advance north it may be just temporary or could signal a decade long  habitat “reversal”. One of the factors I have noticed is that the cooler periods have become less cold and shorter.) The Megalops and star crab sizes appears to be happening later, too late to perhaps ensure good survival. By the 1930s (Jeffries Rhode Island Study) Narragansett Bay commercial blue crabbers most likely were asking the same questions as today.  From a large fishery in 1912 dwindling each year until 1938, the New England Hurricane signaled a habitat reversal of unprecedented  scale, cooler longer winters generally happened after.  By the late 1940s and 1950s winters were cold and snow filled, and New England commercial blue crabbing ended.  It is mentioned in the historic literature (not as much as staple market species), but something had happened, no one knew what, but blue crab populations were lower and in some areas now gone.  It was the time that clouds these events; habitat transitions are usually not sudden and therefore disguised by many factors, one of which is a species rehearsal, from the 1895-1905 Southern New England lobster die-off did come before on incredible surge in blue crabs. Habitat quality later improved for lobsters it could be years before legal size lobsters entered a fishery.
When Southern New England experienced critical lobster die-off in 1998 no deadlines read “Lobsters’ Demise may signal the return of blue crabs”.  We did not know the environmental fisheries history and patterns fishers call cycles.  I did not fully realize the signs as well.  It was my son Willard and his friend William who would fish for blue crabs in Essex in 2004; they didn’t take in hundreds but what they did return home with in huge buckets were huge males, very large jimmies the size to which I was not accustomed. It actually was Willard who called me in 2010 urging me to visit the Essex Town Dock as crabbers were catching hundreds of blue crabs and carrying them off “in plastic laundry tubs.”  In 2006-7 catch rates were in the dozens of crabs perhaps (4 lines), one of our best crabbing locations was the out flow of Fall Mills River off a dock, two 5 gallon pails (80 crabs about) was not uncommon; also I might add an unpleasant tug of a snapping turtle that seemed to try to pull you into the water as well.  By that time (2007) crabbing had increased all along the shore area, even into Mystic and Pawcatuck Rivers.  New Haven Harbor Monitoring studies in the 1970s (a requirement of a state permit) listed the most prevalent species in the harbor and in the middle 1970s as lobsters they were among the most numerous, blue crabs were listed as scarce. 
Many thanks to Paula Daddio, one of the Aquaculture Science teachers here at the Sound School, for providing me with a copy of New Haven Harbor Ecological Studies 1981 Summary Report 1977-1980 (prepared for the United Illuminating Company, New Haven, CT). It provides a great look at what species were prevalent in New Haven Harbor following a gradual warming that started in 1972. The report is a comprehensive survey of water quality and fish/shellfish species as part of a permit discharge requirement. One of the key charts in this report was a 1974 to 1980 ranking of the ten most prevalent epi-benthic species (New Haven Harbor) on page 76 and a surprising surge of lobsters – moving from 10th to 5th most abundant (selected sample stations, New Haven Harbor). This was perplexing to the study authors who on page 69 noted that surprising increase:
“Lobsters have shown a notable increase in catch abundance during recent years. In addition to higher catch abundances, lobsters were occasionally abundant during mid-summer. The period in previous years when densities typically declined.”

The climate was warm but not hot. Winter storms (except for the Blizzard of 1978) were less severe. Although blue crabs were sampled, they did not make the top 20. In fact, the most prevalent crab was the cooler water preferring Rock Crab (Cancer irroratus) and was noted to be consistently abundant. “Seasonally rock crabs have been collected in highest numbers during the summer (pg. 68) [Blue crabs were only occasionally sampled].

Some years none were observed. In the time span for four decades lobsters and blue crabs had reversed in prevalence (New Haven Harbor).  By 2012, blue crabs were very prevalent in New Haven Harbor.  Sampling trips by our own Island Rover research vessel small otter trawls with Jack Cardello, Jack Walsh and George Baldwin, Sound School teachers. often come up with dozens of blue crabs. The New Haven – West Haven Shoreline became a favorite area to flood light “dip” crabs. When blue crabbers experienced these dense populations it was difficult to compare to surveys in the 1970s that listed blue crabs as “scarce or unknown” in the same area.


What the future will bring us is uncertain, but climate conditions have changed, and some of the colder climate indicators # days snow on the ground and# days of ice on, ice off days might be helpful now. The North Atlantic Oscillation (also at times called the Arctic Oscillation) has produced a strong polar vortex sending cold waves deep into the US, “Winter kill” species included not only the blue crabs, but others that over winter in Sapropel type habitats, terrapins and even conch as well.


Are High Catches Sustainable?


Sustainable has been a fisheries buzzword for the past two decades; it has displaced our fishing in describing some of our most valued fisheries. If climate change dictates changes in habitat quality which I feel it does- than climate itself has a huge role in the fisheries  sustainability discussion.  Fishers call it cycles. I term it as habitat reversals; one of the best associations in New England to climate changes (cycles) is the striped bass.


As more historical information is coming in (including a recent collection of striped bass journals) the peak striped bass years were from 1896 to 1921 as recorded from catches from Boston to Monomoy, Massachusetts (pg. 10, Fishery Bulletin of the Fish and Wildlife Service; pg. 10, Studies of the Striped Bass of the Atlantic Coast). This period is within the 1880-1920 “Great Heat” period in which blue crabs, oysters and striped bass surged to levels not recorded before. Researchers were noting the fishery period, but not the heat. They were, however, investigating the range and size of stripers – in times of great cold, very small – ten pounds or less; in times of great heat, huge and often record breaking.
Researchers then were not recording climate change events; still placing most investigations into catch statistics and reproductive capacity. The climate factor, other than in very important fisher observations, was largely overlooked. The sizes of these stripers were not overlooked however and some of the largest stripers caught in New England came during “Great Heats.” This section on page 4 of the U.S. Fish and Wildlife Service Fishery Bulletin #35 1941 – Studies of the Striped Bass of the Atlantic Coast by Daniel Merriman, Yale University, New Haven, CT, Osborn Zoological Laboratory describes this situation a century ago:
-from 1941 Report by Daniel Merriman” pg. 4
Size and Range of Striped Bass

“Size and Range of the Striped Bass as referenced by the US Dept of the Interior; Studies on the Striped Bass (Roccus saxatilis) of the Atlantic Coast by Daniel Merriman (Fishery Bulletin of the Fish and Wildlife Service, Volume 50, 1941. The striped bass most commonly taken at present by commercial and sport fishermen on the Atlantic coast vary in size from less than 1 pound to about 10 pounds in weight. Individuals up to 25-30 pounds are caught, although, judging from old records, these larger fish are not as abundant as they have been in the past.  Bass above 60 pounds are now decidedly rare. The largest striped bass taken in recent years was the 65-pouder caught on rod and line in Rhode Island in October 1936 and one weighing 73 pounds was taken on rod and line in Vineyard Sound, Mass., in 1913 (Walford, 1937). Authentic records show that a striped bass weighing 112 pounds was taken at Orleans, Mass., many years ago (Bigelow and Welsh, 1925), and Smith (1907) reports several weighing 125 pounds caught in a seine near Edenton, N.C., in 1891.”


I can recall listening in 2009-2010 to reports about the star crabs size blue crabs in Perry Mill Pond, Fairfield.  (Some of the most interesting reports have come from kayakers). The description of blue crabs by the hundreds of thousands that carried to the 2011 blue crab year and several of the first reports listing the numbers of 3 small crabs as greater than legal size reports came from western CT.


The reports of small blue crabs sometimes followed crab hatches such as the one I observed several years ago off Faulkner’s Island, Guilford. Crab larvae filled the water column then for several miles but what was the source of this tremendous hatch of it wasn’t “ours” or was it the larvae that somehow drifted up into our area from southern areas such as the Chesapeake Bay region? The amount of female blue crabs there more than doubled-- 100 million to over 200 million – and if reproductive success factored in catches should have risen over the same period but they did not, instead they were level and declined. One may consider a regional climate factor instead; unfavorable winds and perhaps the Gulf Stream may have carried Megalops far to the north in larger quantities. A gradual warming allowed that set to mature here such as in areas of Perry Mill Pond in what seemed at the time to incredible densities. The warm summers of 2011 and 2012 also had reports of CT female blue crabs holding sponge egg masses and added to whatever Megalops set drifted north (Bridgeport & New Haven Harbor).  But the “new normal” may have just returned to the old normal of long ago, in times of Great Heat and low storm intensity blue crabs moved north as they did a century ago. For New England the high catches of Blue Crabs are not sustainable over time- looking at the patterns of fishery landing statistics of the past century, they change over long periods of time in large event cycles are just do not fully understand. The fishery statistics for blue crabs are high during the Great Heat 1880-1920 and low in the late 1950s and 1960s. This is also the period of a negative Northeast Atlantic Oscillation or NAO.


Kudos and thanks goes to Sam Sampieri of Fox TV news here in CT for during a weekend broadcast Sunday April 25 mentioned the NAO, a cold air mass was settling over New England and stated something to the effect “this is typical of a negative NAO pattern.” And is to my knowledge he was the first Connecticut forecaster to mention the NAO during a television forecast.  I was very surprised to hear it mentioned and hope that a follow-up will come- it was long overdue (my view).


When you examine the historical fisheries literature, most species over time show periods of abundance then decline. Researchers are now looking at the NAO for the increase in cool water fisheries such as shad and herring in the 1950s and 1960s and declines in the very warm 1974-2008 period.


Temperature Impacts Habitat Quality


As colder water contains more oxygen Connecticut River researchers rejoiced as oxygen saturation levels increased in the Connecticut River during the late 1940s often suggested in response to a lessening of pollution (Moss Douglas, The CT River) Pollution was Decreasing- writing in 1965- Director Moss writes.

“It is probably very unrealistic to hope that the Connecticut River will ever return to its original state of cleanliness and purity – the encroachment and impact of civilization is simply too great.  It is felt, however, that a tremendous amount of improvement can be accomplished. There appears to be a new awareness of the abuses and the record of regression to which our beautiful river has been subjected. This consciousness is being demonstrated by a gradual improvement in water quality. Our Water Resources Commission makes the encouraging observation:

“Over the pat several years, considerable pollution control work has been accomplished in the Connecticut River watershed, resulting in the improvement of the quality of the river. This improvement is probably best shown by comparing the results of three dissolved oxygen sampling programs carried out in the years 1914, 1929 ad 1953. In each program, samples were collected at several stations between Hartford and Bodkins Rock, Portland. The average per cent saturation for dissolved oxygen for each series was 1914—26%; 1929—43%; 1953—65%.  There appears to b e no doubt that conditions are even better today (note: per cent saturation of dissolved oxygen is often employed as a criterion for indicating water purity.)”


But in looking back, colder water contains more oxygen and Director Moss just reflected on a trend toward cooler waters which returned these species that liked cooler waters yet vanquished those who liked the heat. Blue crab catches in the 1950s-1960s dropped over Southern New England including the Cape and Islands of the species that appears to benefit the most from cold and stormy period is our bay scallop, the second being winter flounder.


After the sudden change in our winter weather at the end of December 2014 by the middle of January bay scallops had settled into all of the eastern CT Rivers.  If the summer remains average without extremely hot temperatures we may see a good fall bay scallop crop. Several of the towns on the Cape and Islands are also experiencing an uptick in record bay scallop catches, now that some of our bay bottoms have been cleared of Sapropel deposits. Bay scallop catches are also something to watch; over time their abundance has changed greatly, casting doubt if they also can be always at high levels of abundance.  The quest of sustainability will be with us for quite some time but the answer from historical recordings indicate that high catches are not sustainable for a variety of reasons most of them natural fluctuations that in the final analysis we have little influence- climate and energy cycles.


Eelgrass and Sapropel Cycles

One of the things you observe by looking at historical literature is certain conditions appear to repeat themselves, one of which is the Sapropel/eelgrass cycle and impacts to shellfish populations.  It could be said that a decline in oyster productivity was accompanied by an eelgrass die off perhaps the first indication of massive habitat change is ahead.  In the historical texts very often 1931 is a transition year with a cold period following striped bass.

No one would doubt that during the very warm period here 1880-1920 blue crabs flourished in northern New England areas and Sapropel deposits grew deep. Those accounts are in US Fish Commission Reports.  As energy lessened and temperatures increased, the soft upper deposits in quiet coves and bays most likely failed first – I observed that happening in Buttermilk Bay on Cape Cod in the early 1980s.  Areas that were once productive for the soft shell clams were buried by a foot or so if soft black mayonnaise.  You could feel the firm bottom below when walking (anyone who has walked in this stuff will realize it is not the same mud as found lower in estuary in places of greater tidal energy) and if you disturb it the black sands below will be exposed with dead or empty shells.  You can at times smell the sulfur but this was the material that still containing dying eelgrass and had become a popular blue crabbing spot.  Blue crabs frequently were observed near these deposits and most likely over wintered in them.  The cooler clean and green eelgrass did contain large numbers of crabs (mostly green crabs) and there is little doubt that these areas once provided food and shelter to many organisms.  But Buttermilk Bay was in a state of great habitat change, the once firm bottoms on the Cape were transitioning (and elsewhere in southern New England) to soft ones.  I believe that over wintering Blue Crabs in shallow Sapropel actually benefited – the slight waft of sulfide from it was a signal to predatory fish to stay away – levels would alarm predators but not be toxic.  That is why I believe is how eelgrass got its name – the soft tissue and preferred bait for blues and stripers also buried into this gelatinous deposit – among the eelgrass plants to escape much the same thing.  In the historical fisheries in times of ice and cold winter flounder spear fishers headed to shellfish beds (mostly soft shell clam beds) while eel fishers headed to “eelgrass.”  Spearing eels in deep soft holes is frequently mentioned and the association of eelgrass to growing organic deposits is widely acknowledged. Eels have a very complex respiratory pathway.

So, one of the questions about “winter kill” that I have heard often for the blue crabs this spring is--Is it related to cold water or is the cold water related to its ability to kill?  If the crabs hibernated in shallow Sapropel deposits – less sulfide perhaps than deep deposits with sulfide levels that could purge in a long cold winter to toxic levels?  One of the largest habitat questions related to Blue Crabs abundance is how winters kill crabs and if winter kill has any habitat characteristics.  Eelgrass itself appears to have mixed habitat services the lower reaches clean and green positive – for small crabs, the upper reaches, brown and furry negative- it could signal the beginning of massive habitat changes as it did in the 1880s  and 1950s and in August, I hope to have a large historical report on how cold water kills blue crabs, and other species.
All reports of blue crabs help our understanding of the blue crab cycle in CT. Please email your blue crab reports to: tim.visel@new-haven.k12.ct.us. All blue crab observations are valuable as we learn more about our blue crab population. Questions? Send me an email.

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 susan.weber@new-haven.k12.ct.us.
The Sound School is Regional High School Agriculture Science and Technology Center enrolling students from 23 participating Connecticut communities.



Tuesday, June 30, 2015

In case you missed it: Discovering the Monster Crabs of the Old Chesapeake

The following article and interview by Tom Pelton at WYPR in Baltimore (originally posted here in January) describes new research from my lab at the Smithsonian Environmental Research Center on ancient blue crabs. Click here for a link to the original WYPR story and podcast of the audio interview. For our paper in the Journal of Archaeological Science, click here.

Discovering the Monster Crabs of the Old Chesapeake

Blue crabs are an important part of the Chesapeake region’s culture, diet, and economy. But crab remains are rare in archeological sites around the Bay. This has led some scientists to believe that Native Americans did not eat the beautiful swimmers that today we find so delicious.
 “What we know about Native Americans ate is based on some historic records, but also on looking at the trash piles that Indians left, mostly on the shoreline of Chesapeake Bay,” said Tuck Hines, Director of the Smithsonian Environmental Research Center. “And the majority of those trash piles are made up of oyster shells. But not much in the way of blue crab remains are generally found in those trash piles or ‘middens.’”

It might make sense that Native Americans did not eat blue crabs.  After all, blue crabs were not a commercially harvested species -- even by European Americans -- until after World War II, when the crab pot was invented as an underwater trap. 
In the century before that, oysters were the most popular food from the Chesapeake.  It the past, highly targeted seafood included terrapin, American shad, and sturgeon -- all of which were over-fished nearly to extinction, until little was left to eat in the Bay except the ornery, edgy blue crabs.
Maybe Native Americans had no reason to mess with blue crabs centuries ago -- because they had so many other, larger morsels of protein they could pluck from the bay with more ease.
The problem with this theory is that records from the 1600’s show that Native Americans were interested in blue crabs as a source of food.
“If you look back at the records of when colonists arrived, and negotiated fishing peace treaties, including hunting and fishing rights in the Chesapeake Bay region, those descriptions and those treaties including rights for crabbing for finfish as well as a collection of oysters,” Hines said.
If Native Americas were negotiating for crabbing rights, why are crab shells missing from Indian archeological sites, while oyster shells and even fish bones are common?  To solve  the mystery, Hines and colleagues at the Smithsonian re-examined old trash piles around the Bay using a new technique.  They used sieves with a very fine mesh.
Scrutinizing historic sites more closely with these sieves, the researchers discovered  tiny fragments  of crab shells in 93 different Native American refuse heaps  around the Bay, some dating back more than 3,000 years, according to an article that Hines and colleagues published last month in the Journal of Archeological Science titled, “Archaeology, Taphonomy, and Historical Ecology of Chesapeake Bay Blue Crabs.”  His co-authors are Torben Rick, Matthew Ogburn, Margaret Kramer, Sean McCanty, Leslie Reeder-Myers  and Henry M. Miller.
Their conclusion was:  Native Americans, in fact, ate plenty of crabs.  But the shells broke down over the centuries, perhaps in part because of acid rain from coal fired power plant pollution in the 20th century.
“The main part of the blue crab that carries forward in these middens are the tips of the claws, which are the most calcified hard part of the crabs,” Hines said.
Analyzing the size of tips of the crab claws they found, the scientists extrapolated how large the crabs must have been. They concluded the crabs caught by Native Americans were much larger than they are now – some twice as large as the typical five inch crab caught today.
“We’ve found middens that contain crabs as large as 10 inches, which is a quite large crab,” Hines said.  “So that’s interesting.”
These giant crabs were not a different species. They just lived longer, because they faced less fishing pressure.  Crabs today typically do not live more than two or three years because most are quickly scooped up by watermen using dredges or pots. Every year, about half of all the adult crabs in the Chesapeake Bay are caught.  But back in Native American times, maybe one percent of blue crabs were harvested every year by people using baited lines and dip nets.
So blue crabs lived as much as twice as long, and grew up to twice as big. Imagine those meaty crab feasts on the Old Chesapeake Bay, with those monster crabs.
The lesson we can learn today from these ancient garbage heaps is that we can have more of what we love if we take less.
(Photo at top of Tuck Hines and blue crab from Smithsonian Environmental Research Center)

Monday, June 15, 2015

2015 Connecticut Blue Crab Special Notice #1

From Tim Visel at The Search for Megalops:

The Search for Megalops

Special Notice # 1 – Blue Crab Winter Kill
- Habitat Transition Now Apparent –

Blue Crab Research in Long Island Sound
You do not need to be a Scientist to report!

(IMEP Habitat History Newsletters can be found indexed by date on the
BlueCrab.Info™ website:  Fishing, eeling and oystering thread)
and CtFishtalk.com™-Salt Water Reports and
the http://bluecrabblog.blogspot.com/

Tim Visel, The Sound School

June 15, 2015

Blue Crab Winter Kill
This spring has been somewhat discouraging for blue crabbers along the Atlantic Coast – first as an indication that a large amount of our over wintering blue crabs have perished and second a weak showing in the 2014 Megalops set.  First winter kill reports from the Chesapeake Bay report as much as 30% have died but along our coast 60% or more from early reports.  The long cold winter is now suspected to have allowed sulfide levels to rise especially under ice – to those lethal to Blue Crabs (and perhaps over wintering Terrapins as well).  Winter kills of fish, oysters, blue crabs and turtles are not new but indications of rapid habitat change.  Fish trapped in deep holes under ice can be killed from sulfide – the by product of organic matter digestion, coastal salt ponds appear to be the most vulnerable (and unfortunately one of the few habitat refuges for blue crabs) in our area.  For example the Black Hall River in Old Lyme is now suspected if a sulfide fish kill last February (2014) when ice formed and about 1,000 striped bass were killed.  Conversations with area blue crabbers mentioned previous winter fish kills of stripers– not as large but accompanied by the smell of sulfur.  The most susceptible winter kill areas are small coves and bays with long “weak” connections to the Sound – frequently described as “poorly flushed.”  Such areas tend to collect the deepest organic deposits – when in high heat these areas undergo ammonia/sulfide generation.

In the scientific literature such deposits are mentioned as “fine muds – low oxygen sulfuric oozes” but many fishers call it Black Mayonnaise (Sapropel).  A cold winter with many powerful storms – turns over this marine compost much like a huge shovel releasing tremendous amounts of nutrients for spring algal blooms.  Areas that once held deep soft deposits of organic matter undergoing sulfate digestion (sulfur reducing bacteria) can release a sulfuric acid wash with a dramatic pH drop – increasing toxic impacts.  These kills are more frequently associated with black waters following storm events.  In time coastal storms over a period of years may transition sulfuric oozes (black in our area from iron) to sandy shelly brown mixtures with some mud but loose and not sticky.  It is these “recultivated” marine soils that can sustain heavy sets of shellfish such as the Long Island Sound and Narragansett Bay great Quahog sets in the 1950s and 1960s (cooler period more storms).

Habitat Transition -

A recent shell hash seagull survey (June 1) at the Niantic River state launching ramp (parking lot) yielded about 30% of dropped shells were in fact bay scallops (sea gulls don’t waste their time dropping empty shells to crack so this is a quick way of determining locally what’s around) and 60% were quahogs – the rest mussel, oysters and soft clam.  Around January 20th bay scallops moved into the lower reaches of eastern CT Rivers.  This is another indication of a major habitat transition – the return of bay scallops to Connecticut.  Habitat transitions are usually marked by sudden climate and energy shifts and the increased occurrences of multi species winter die offs.        

Habitat transitions in the historical literature are not quick they in the past took decades and a return of warm winters and few storms would help the blue crabs – last winter obviously did not.

Any reports of Blue Crabs (dead or alive) would be a help – all observations are important. 

Thanks for your continued interest – tim.visel@new-haven.k12.ct.us