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 #3
August 15, 2014
You Do Not Need to Be a Scientist to Report
· Crabbing in Saline Areas Improves
· A Long Term View about Fishery Management
· Blue Crabs, Sapropel and Habitat Capacity
· Attention Connecticut Crabbers – Megalops Survey Postponed
Crabbing in Saline Areas Improves
Since the last report crabbing in deep saline holes has improved. The areas are best described as deep bends or rivers that act as linear salt ponds. Catches from these areas improved a bit while upper reaches have generally been slower. Crabs seemed to expand into these areas slightly the first two weeks of August; however cooler temperatures and rains pushed back the crabs to these deeper more salty pockets. Some areas that were productive previous years are now filled with leaves. If these areas are leaf filled and periodically produce bubbles chances are it is now a sulfur reducing area (Megalops, Report # 2, August 4, 2014 ) try areas closer to the Sound.
This summer crabbers that had small boats and have been able to fish these areas and have consistently reported the best catches. We’ve had a relatively dry period and crabs moved into shallow areas, but after rainfalls seemed to push crabs back. Blue crabs have appeared at the Essex Town Dock twice only to move after heavy rains. The upper Connecticut River crabbers continue to report slower catch rates, sometime is as few as one crab per hour. This is of course, a marked difference from the past three years at Essex (see following section).
The cool summer temperatures have caused a second delay in looking for any Megalops sets. A June/July spawn should be observable in September.
Thank you again for all habitat and catch observations this summer
A Long Term View about Fishery Management
I have had dozens of dockside conversations with blue crabbers this summer. For those who started crabbing a few years back, the question is often brief, “what happened?” I have had many crabbers contacting me about the decline of blue crabs here and it’s far too soon to make predictions. That is something we like to do and avoids the phrase, “I’m not certain” or “I don’t know.” But that is just it, I don’t know. That is why the fisheries history aspect I feel is important, especially with current climate change public awareness. Is our climate changing? Most certainly it is. Are we in new climate change habitats? No we are not. From the historical records it is reasonable to determine that warm and cold periods have happened here before, in fact many times. From current research into habitat trends, it has been three very cold winters in quick succession historically that resulted in the lowest blue crab catch outcomes (Although I am a member of the EPA-DEEP Long Island Sound Study Partnership, this discussion in no way represents the Long Island Sound Study, the Citizens’ Advisory or Habitat Working Group Committees).
The rise of blue crabs during increasing heat and followed directly after a die-off of lobsters as they did here a century ago. Many will look to human causes of these declines and events and that also appears as well in the historical fishery literature. As Rhode Island reports at the turn of the last century mentioned factory wastes as a cause of the lobster die-off in 1898, but remained quiet regarding the “oyster explosion” in the Upper Narragansett Bay or soft shell clams often within the same areas during the same year at the same time. (Rhode Island Report of Inland Fisheries, 1906, Section VI, page 14
As Rhode Island bay scallop production dropped by huge amounts believing that in 1898 bay scallops were perhaps extinct, striped bass then grew to enormous sizes. The 1901 Narragansett Bay soft shell clam set was so thick – over 7,000 clams to the shovel as was described in the State of Rhode Island shellfish reports. Clams pushed each other out of the soil and the soft shell clam sets after 1898 were immense. And in 1902, Newport, Rhode Island started listing crabs as an export item while swordfish catches started in 1896 and grew steadily as lobster catches continued to plummet. (Annual Report of the Commissioners of Inland Fisheries, January Session, 1906, State of Rhode Island , Providence Plantations .) The best black sea bass year in decades that was also 1898, the year of the Narragansett Bay die-off. They arrived on May 10th and heavy catches began on May 12th, 1898. (Tracy -1909- Fishes Known to Inhabit the Waters of Rhode Island – Page 123) In 1898 there were no regulations in Rhode Island for blue crabs and historically regulations follow a decline from high population levels. Lobsters, for example, were once used to be used for fertilizer or as “pig fodder,” but after declines in the 1890s management regulations were enacted. Although much can be learned from catch statistics when fisheries drop (and especially for those that drop quickly) the increase in regulatory authority and catch restrictions often follows a “fishery failure”. This appears often in the shellfish historical records for seasons, size and catch (creel) limits as well. A fishery failure usually follows a habitat failure within two life spans, and for blue crabs with such a short life span these changes can be represented and large fluctuations in the history fishery landings in just a few years. We may be seeing that now.
Some of the frustration experienced by blue crabbers this year as to what happened can be perhaps answered in the next few paragraphs. Habitat reversals tend to be quicker on land – the law of habitat succession but in the marine environment it takes decades. By the time habitats have reversed previous catch levels are forgotten. The recent “run-up” in blue crabs was set back in 1972 – successional habitat transition until 1998 reaching perhaps the highest habitat capacity in 2010 – nearly 3 decades later.
The following section describes the Narragansett Bay experience at the turn of the century. The Narragansett Bay (Rhode Island) records are more accessible currently than Connecticut fishery records. By 1895, Rhode Island fishery managers were aware that something was wrong with increasing heat huge species transitions were underway – New England was in a period of intense warming, very different from the 1870s of brutal cold. The year 1898 was a tough one for Narragansett Bay (the fish die-off of 1898 was still talked about a decade later) and led to “investigations” almost as though something criminal had occurred. Fishery managers and officials were frustrated with changing climate conditions and one of the first questions asked in 1899 was what species were in fact native to Rhode Island waters? The first report developed by Dr. Bumpus (1900) was changed in 1901 and changed again with records on “rare species recently caught.” The list was changed again in 1901 twice and also again in 1905 and 1906 and revised again in 1909. Some of the frustrations of fishery managers are evident as they tried to get a grip on rapidly changing observations. We often call that the “new normal” the problem is of course the new normal may not be that “new” after all. (Megalops Special Report #2, February 2014 )
This final 1910 Rhode Island report makes mention of “fishes which are particularly rare or whose distribution is of particular interest. The occurrence of such species in the waters in Massachusetts, southern New England and Long Island, is of special interest in the study of the fauna of Rhode Island” (page 37, Fisheries Known to Inhabit the Waters of Rhode Island, Henry Tracy, Biological Assistant, Wickford Station, 1910). In other words, what Rhode Island officials were experiencing also was regional in nature – What is going on in our neighboring states? The questions are very similar today and what Rhode Island officials found frustrating was they were experiencing the sharpest habitat reversal in perhaps three centuries back to the 1620s, the Mini Ice Age. It was hot and warm temperatures fish were now being seen in Rhode Island waters. One of the questions was should Tarpon be included in the list of Rhode Island fishes? Every time it seems the list was formalized, new species suddenly appeared. It was like trying to grab an eel with soapy hands just as researchers thought they had the list complete, changes needed to be made.
In 1895, two tarpon were caught in a fish trap in Coddington Cove, Newport, Rhode Island, between 1895 and by 1906 fifteen more tarpon were caught; 9 alone in 1906. It was finally included in page 72 as “rare.” Then came a surprising haul of Mullet 500 barrels (1,200 bushels) in October, 1904 off Newport and a specimen of this catch was sent to the National Museum (which we now call the Smithsonian) for identification (1910, Tracy Report, page 97). This apparently was the “tipping point” and caused more studies of “the Bay.” Tarpon and mullet in Rhode Island waters, a die-off of lobsters and disappearance of bay scallops that is what was spurring public policy discussions (and studies) which was the sharpest habitat reversal in centuries. The Narragansett Bay “trusted” species of value were now gone – soft shells, oysters and later blue crabs surged instead in Rhode Island’s now warmer waters. Eelgrass meadows now covered previous bay scallop habitats. It just wasn’t Rhode Island, but the entire southern New England region. The Great Heat was happening and with it different habitat quality and new species not abundant here before for quite some time. In simple terms, “It got hot.”
Although tarpon was included in the species list finally in 1910, it would be another decade before it would turn colder. Land areas heat up faster than water in New England, but water (bodies) retains heat longer. That occurred in the New England Ice Panic of 1899-1900 when large bodies of water did not freeze, creating a shortage of ice and spurring the development of “commercial ice machines.”
The climate pattern changed in 1922; it started to get colder and the bitter winters of the middle 1920s surprised Rhode Island fishery managers who now witnessed the return of bay scallops. They were surprised to report that despite the bitter winters, bay scallops productivity had actually surged. They just could not understand it at the time. Bay scallops habitats had benefited from the cold. Their habitat quality has enhanced by storms and cold and improved habitat quality soon favored bay scallop abundance and then, of course, catches.
If it turns colder (still too early to tell), blue crabs will decline and lobsters over time will increase. That has happened here before. That is what makes the megalops set so important. It is thought that later megalops sets don’t survive here; year’s later blue crab catches quickly drop because of its short life span and limited “fringe” habitat capacity in northern waters.
The reproductivity of the blue crab could be an important indicator species for climate patterns and the “test” perhaps of such patterns is the strength, timing and duration of Megalops sets.
Blue Crabs, Sapropel and Habitat Capacity
One of the areas of recent study is the concept of bottom aquatic habitat stability. This a feature of often intense clam sets following severe storms, the wave and storm tides that act to cultivate sub-tidal marine soils freeing them of organic acids, opening pore space and reducing acidic conditions if this sounds like shoveling or cultivating garden soils, it is only on a much larger and natural scale. Some of the best soft shell clam (warm periods) and hard shell clam (cold periods) sets have come following hurricanes when habitats then stabilized.
For a warm water set the New England 1901-1903 sets of soft shells and the 1940-1945 cold water sets of quahogs are classic natural cultivation events. Marine soils that sit eventually become too acidic from organic matter, similar to terrestrial soils. The hurricanes of the 1950s and early 1960s are suspected of even helping offshore heavy sets of surf clams off the coast of New Jersey. But what if the soil is constantly cultivated? The habitat upon which clams set then becomes “unstable” and if constant any new sets are soon destroyed by the next storm. No master gardener would rototill a back yard garden, plant it and then rototill it again the next day, but nature can do that and a series of coastal storms can create long or short periods of habitat instability. That is aside from temperature, another huge factor in species abundance is energy. Energy can be from wind or moving flowing water; one of the ways energy is applied to estuarine habitats is from rainfall.
Reports from Connecticut crabbers and some blue crabbers in southern areas report the upper reaches of rivers contain very few crabs, yet at the same time report changes in the bottom conditions (much mud, leaf material silt and other organic debris). Comments like grassed over, thick soupy bottoms soft muck or foul bottoms (odor) all signify a declining habitat quality. In some areas I suspect re-suspension of sulfur rich Sapropel under ice and movement of organic debris by heavy rains. This movement of long decaying organic material can release toxic hydrogen sulfide compounds; the same toxic material that has long plagued fish aquarists. It’s also very similar to organic material that collects above dams (Megalops Program Report #2, August 4, 2014).
New England blue crab habitats have recently had both, bottom instability (Irene, Sandy and Nemo) and currently much cooler temperatures. A third habitat issue has now come into view, precipitation. Over the last century Connecticut has “greened” once large areas of cleared agricultural fields have succeeded to forest cover and with the trees, come the leaves and leaves move with heavy rains. George McNeil, who once grew oysters in the lower Hammonasset River in Clinton, Connecticut, used to wait with anxious anticipation, both ice and rain, seemed to assist leaf deposition in estuaries. Rains by active water flows (storm waters) would gather leaves and pieces them and brings them to the Hammonasset River as the current slowed leaf material would fall out covering his lower river oyster beds. Intense cold also would create scour water flowing under the ice created Venturi like “mud storms” that would under the right conditions move tons of leaves. It was according to Mr. McNeil as someone dumped 3 feet of leaves on your front lawn in just a few weeks.. He would rake off the leaves from the oysters using open frames in early spring before they suffocated. But what if he didn’t? The leaves would rot; suffocating bottom habitats (and oysters) and releasing in high heat high amounts of ammonia and concentrating sulfur compounds, many of which are highly toxic to marine life. And leaves, especially oak leaves already are highly acidic would compost over acidic marine soils.
The impacts of organic “debris” was well known by shellfish researchers in the 1890s. Dr. G.W. Field of the Rhode Island Agricultural Experiment Station was asked to investigate the decline of the oyster fisheries in Point Judith’s Pond in 1896. The final report in 1900 has this section in the Rhode Island Annual Report of the Commissioners of Shellfisheries to the General Assembly May session 1900, “In brief, the cause of the decline was found to be the deposition of sediment upon the oyster beds; a condition brought about by the repeated closure of the breach, thus making the pond a settling basin for the silt brought down by the Saugatucket river. The silt and detritus, settling upon the oyster beds, kill the oysters by smothering.”
It is just not in Northern waters that organic matter impacted sub tidal habitats a century ago, but Southern areas as well. E P Churchill of the Department of Commerce Bureau of Fisheries writing in 1919 (The Oyster and Oyster Industry of the Atlantic and Gulf Coasts) details places in the Chesapeake Bay and bays on the New Jersey coast where rapid deposits of “vegetable matter” can cover oyster beds, on page 16 states: “During warm weather this organic deposit is likely to undergo rapid decomposition, the toxic products of which sicken and kill the oysters.”
Most references to decaying organic matter as a negative habitat type mention summer heat and the possible low oxygen formation of Sapropel. Sapropel concerns continue today even in the fresh water habitats, especially canals and reservoirs out west. A July 2012 Central Arizona Project (CAP) mentions the formation of Sapropel from bacterial reduction of organic matter in water with oxygen deficits (Pg 22 contains this quote): “this reduction may lead to Sapropel formation a compound that is high in hydrogen sulfide and methane, and has a shiny, black color due to the presence of ferrous sulfide. This compound is responsible for the occasional “rotten-egg” odor (of water).”
Something similar may be happening now to blue crab habitats, clam shell habitats and eelgrass. Eelgrass is the habitat to watch for crabs and like oyster beds, eelgrass cannot take vast quantities of decaying organic matter. Eelgrass as other organisms also appears to have a “habitat clock” and is killed by excess organic matter. Two Danish biologists last year investigated the appearance of huge rings in dense eelgrass meadows in the Baltic Ocean. The explanation was that eelgrass plants trap the mud and they also in the process trap poisonous sulfides. “The high concentration of sulfides that is trapped, in the midst of the older eelgrass that is less capable of withstanding the effects of the poison gets killed off, leaving only eelgrass (younger plants) that encircles the deposits of sulfide-rich mud” thus a ring. (University of Copenhagen – Jens Borum, “Coves of South in Denmark”, Mariane Holmer February 2, 2014. Organic matter in high heat has the ability to transition habitat types in relatively short periods of time.
The past few years I now suspect that several western Connecticut coves and bays have obtained deep storm driven deposits of leaf matter. Storm water carries a brown, oatmeal chaf of ground up stems, blades and other terrestrial vegetation into water bodies. In the presence of oxygen, this appears as a brown chocolate layer, but below in the absence of oxygen, it turns black. Heavy rains can carry this organic matter and the event that makes me suspicious are the July-August 2011 reports from western Connecticut crabbers degraded blue crab habitats (Megalops Report #12 August 2 2011).
Some crabbers have noted this material as well, even from last year. In cold water this organic matter is broken down by grazers that consume it; some clammers that use a plunger for soft shell clams, for example, may recall immediately following seeing sand shrimp come in close to feed. In warm water over time with less oxygen this material becomes Sapropelic, reduced by a host of primitive bacterial strains from the time when sulfur ruled the earth and not oxygen. The availability of oxygen in today’s atmosphere has pushed the sulfur cycle from the habitat agenda, but it is still here, mostly hidden from view. Not too much is written about Sapropel because it is usually associated with the older sulfur cycle and is, for the most part, a natural process. But every sub-tidal habitat is subject to it now when oxygen is in short supply; sulfur reducing bacteria lie in wait ready to again consume organic matter (leaves) as they have done for millions of years. It is this process that creates very deadly sulfides and ammonia, nutrient that supports harmful algal blooms (HABs). It is this material that when disturbed by crabbers gives off the smell of sulfur. When sulfur is noticeable to our senses, 100 parts per billion it is at a level that is toxic to crab Megalops. (Reefkeeping Magazine – hydrogen sulfide and the reef aquarium). A byproduct of the sulfur bacteria is sulfuric acid and this lowers the pH level of marine soils making clam sets almost impossible; it kills clam larvae on contact. Sandy, bivalve shelly bottoms also hold small blue crabs providing cover and feeding opportunities. Thick soupy rotting organic matter rich in sulfides is not a preferred habitat for blue crabs.
Attention Connecticut Crabbers
NAO – A Cool Summer The Megalops Survey Postponed Now Until September
For those crabbers who follow the NAO climate pattern, it has deepened now to a negative 1, but zonal flows have flattened out across the United States the horseshoe bulge and moved the storm track to the east. It now resembles a winter Northeaster storm track in which coastal lows approach Cape Cod before veering off to the northeast. This has kept Long Island Sound waters cooler. Although summer temperatures also remain cool, the polar air has moderated but has kept us cooler than average. One of the questions asked recently regarded a prediction for the 2015 blue crab season and one parameter is the timing of the Megalops set, which because of the cooler temperatures, the Megalops survey has been postponed again until September. I want to thank those crabbers who offered to contribute to the survey, but now it looks like September 10th to the 15th will be the best time. If the blue crab larval stage Zoeae survives, it should appear around mid-September.
The spring Megalops set (carry over from last fall) was most likely victim to cooler temperatures, habitat instability ice and freshwater runoff from the spring melt. Several reports have indicated that the upper tidal reaches of large tidal rivers (including the Hudson River in New York) have obtained tremendous amounts of organic debris from heavy rains associated with tropical storm Lee and Hurricanes Irene and Sandy. Most of this leaf debris appears to be oak species, a leaf material with a pH of 4.5 to 4.76, and in the absence oxygen contributes to the bacterial decay (reduction) in the sulfur cycle. The residual compost is often Sapropel which can emit toxic hydrogen sulfide and suffocate crabs in hibernation. When leaf material is too deep it rots in heat releasing hydrogen sulfide which is toxic to fish, crabs and even shellfish. This is not the preferred habitat type for blue crab Megalops, in fact blue crab Megalops are killed by it.
It is thought that some of the previous productive up river blue crab areas now have inches to several feet of dead leaves over them. Many crabbers have posted on regional websites that the lower more saline portion of rivers are more productive. This habitat feature may be a part of this observation. Hydrogen sulfide toxicity may have a part in this habitat transition and why the upper reaches report a very low blue crab presence. One Connecticut River that appears to have obtained tremendous quantities of leaves and now possibly a reduced acidic bottom is the upper sections of the Saugatuck River in Westport.
A notice will be sent out with the September Megalops survey date.
Thanks again for your interest and support.