The Search for Megalops—Report #2—April 2015
The Sound School Regional Vocational Aquaculture Center
Blue Crab Research in Long Island Sound 2015
You Don’t Need to Be a Scientist to Report
· Hope for a Great Crab Year Fades as Cold Continues
· Did Coldwater Reduce Crab Catches on Eastern Seaboard?
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With cold air seemingly refusing to budge – crabbers are concerned about the 2015 blue crab season here in Connecticut. For some western CT blue crabbers the crabs last year “never arrived.” This spring is very different than a few years ago which had large blue crabs being caught in the Guilford – Branford area before the blue crab season “officially” opened on May 1. It seems whether we like it or not we are in a colder period – winters now contain the “polar vortex” bringing energy and precipitation to a cooler New England.
Snowfall records have been broken for Boston and others had snow amounts not seen since the 1960s. Some may recall of the gales of February 1964 and ice walls along Hammonasset Beach in the winter of 1965. The 1960s were tough for coastal residents – colder winters and some of the busiest hurricanes seasons to hit the Northeast. The cycle of Sapropel may be ending and with it some of habitat characteristics that signaled the increase of Blue Crabs in 1998.
For most of my fisheries history research I rely upon US Fish Commission Reports between 1880-1920. But when it comes to the Blue Crab fishery during the negative NAO of the 1950s and 1960s, I look to the same period for Commercial Fisheries Review articles. Thanks to Charles Beebe (late of Madison), I was able to spend a summer day at the NOAA Milford Shellfish lab, 1969`or 1970? Back then it was under the Fish and Wildlife Service Bureau of Commercial Fisheries (It was before the new building). I helped make chicken wire oyster spat collectors for a day. Everyone was very nice and let me take back some publications; two of which were “The Blue Crab and Its Fishery in Chesapeake Bay, Parts 1 and 2” by W. A. Van Engle, then Associate Biologist of the Virginia Fisheries Laboratory, Gloucester Point, VA. I still have them and from time to time give them a review.
In my most current habitat research into the cause and effect of Sapropel and sulfide kills (sulfide waters and black water deaths) oyster growers a century ago also complained of black waters, off flavors and dead oysters in high heat. This was often in the vicinity of black bottoms with strong odors- and mentioned occasionally by clammers. I suspect those bottoms of producing killing sulfide levels.
In winter, blue crabs would also hibernate in these soft bottoms, protected perhaps by the hint of sulfide to keep starfish away. But these sulfide compounds do produce an odor (and perhaps off flavor) and on page 15 of Part 1 is found this paragraph of June 1958 publication CMFR15 is found this quote:
“Crab dredgers report that in winter in the vicinity of Cape Henry, crabs are often of strong odor, here shells deeply pitted and produce a very small quantity of very inferior meat, and catches of this kind are quickly dumped overboard.
Theses crabs may be remnants of “ocean” schools (Truitt, 1939). Those with a strong odor are called “ticky” crabs, possibly because the odor is similar to iodoform which in turn is similar to the odor of bed bugs (bed ticks).”
This off taste or off flavor is mentioned in the historical oyster and clam literature as well. This is an 1876 reference to habitat condition and flavor concerns for oysters:
“The American oysters, like our own, do not prosper on every kind of soil indiscriminately. In pure sand they do not fatten, and grow very little; in mud they contract an unpleasant taste, and also run the risk of being smothered; but in mixed soils of sand and mud they develop to an astonishing degree, especially when the water is slightly salt.” (Source: U.S. Commission of Fish and Fisheries, Part III Report of the Commissions, 1874-1875, Wasting GPO 1876, pg. 297 – Oyster Industry of the United States)
There is even a slight reference to the types of bacteria that live in this anoxic organic matter that today are linked to shell disease. The Von Engle quote mentions “shells deeply pitted” the same type of bottoms off New York associated with the first 1970s lobster shell disease observations.
After 1931 habitat conditions changed it became cooler and stormier; crabs retreated to deeper areas and you can see the development of crab pots then– a response perhaps to habitat refugia to catch them in deeper holes, banks and channels. That happened to some extent last year in Connecticut the surviving blue crab populations were compressed into smaller, deeper salt pond like areas. If you fished those areas you caught good numbers. Habitat compression can explain wide differences in catches over a large geographical region. Compression into those suitable habitats gives an appearance that the fishery is stable (or even increasing) while other areas appear to be languishing. Compression (jubilees) are most often linked to declining environmental conditions that influence bottom habitat quality. Dr. Rhoads (Yale University) predicted a habitat compression scenario connected to Sapropel for Long Island Sound Lobsters nearly two decades before it happened (1984). Warming temperatures and the spread of Sapropel are linked to massive lobster die offs. In the heat of summer warm water near the “sediment – water interface facilitated the release of toxic sulfides and ammonia from the sediments, for the weakening or killing lobsters.” * [Potential Climate Change Impacts On Marine Resources of the Northeastern United States, Fogarty et al 2007 page 22)]The impact of this organic toxic release was devastating to western Long Island Sound lobster population in the late 1990s. The migration of blue crabs from western areas in 2011 may have signaled a larger habitat compression event – often described as Blue Crab Jubilees – also occurring in warm (hot) periods and also linked to organic matter digestion in historic Mobile Bay studies.
Look for the best crabbing in areas that was protected from our winter storms, deep locations such as salt ponds and bays.
Expect the first signals of surviving crabs to be seen by May 15.
Thank you for your continued observations and questions.
Hope for a Great Blue Crab Season Fades as Cold Continues
The trend in blue crab landings over time indicates warming-- less storm filled periods have the highest catch figures. However, excessive heat and a tropical system I feel contribute to sulfide toxicity, “Black Water” deaths in the north and “Jubilees” in the south, both low oxygen high sulfide events can be just as damaging as cold winters and storms. We can observe the low oxygen high sulfide events when blue crabs walk out of the water, which happened in Niantic Bay a few years ago. A very cold winter can kill adults but the most noticeable change is that our Megalops set is very late and perhaps destroyed. Several years later that impact is reflected in a sharp drop in landings. Between temperature extremes and storms combined with a relatively short life span its no surprise that Blue Crab landings over time fluctuate. One of the habitat areas of concern is the sulfate reduction of organic matter, organic waste, mostly terrestrial leaves, in high heat. This can deplete oxygen and then produce sulfur compounds as a “natural” low oxygen sulfate/bacteria reduction pathway. In times of cold or a rain/flood these oxygen-limited deposits are dislodged and creates a sulfuric acid wash. This aspect is most likely to occur immediately after a tropical system – creating a series of habitat limiting conditions, fresh water toxicity, sulfide toxicity followed by a sulfuric acid wash. I believe these conditions can be enhanced by sediment accumulations – such as those behind terrestrial dams carried downstream in thick slurries (see related articles regarding recent Conowingo Dam concerns).
Did Coldwater Reduce Crab Catches on Eastern Seaboard?
The declines of blue crabs in Chesapeake Bay has greatly alarmed some blue crabbers there, seeking management solutions to population concerns. Some of the frustration about fisheries management is often the emphasis upon the landings not habitat; we had that happen recently in Connecticut with lobster fisheries- increases in the legal gauge size, V-notching of female lobsters and finally a closed lobster season (not seen in New England since Rhode Island did it in 1904).
Did it help- most likely no in terms of habitat quality, it got hot and lobster habitat quality declined here although the public perception was that it could help the heat was the real problem. Certainly the V-notching, of female lobsters sought to enhance reproductive capacity (always good) but it would need to get colder to fully rebuild the lobster population here in Connecticut. Reproductive capacity is important but just as significant as the predator/prey ratio. One of the things that did come out recently and something that I noticed also was the predation of shorts (sublegal lobsters released in daylight). In shallow water you could watch Tautog attack these small lobsters and kill them, without cover while hauling traps we would drift away from a rocky kelp covered bottom over smooth sand. In very shallow water (in the late 1960s, early 1970s it was colder and water clarity much better – less plankton). You could watch lobsters darting to escape Tautog predation, which was to increase in abundance into the 1980s. I lobstered with my brother Ray for 15 years and we often wondered how many shorts we released in daylight never made it to the sparse cover our area of the coast provided, cobblestones and kelp was the key habitat for small lobsters, it is most likely patch eelgrass and sand mixed with shell for blue crabs. Some southern blue crabbers have raised similar questions about predation from red drum. In an 1887 description of Maryland’s fisheries it mentions a large drum fishery, the bait for which was blue crabs,
“In this fishery the hooks are baited with crabs or menhaden and thrown well out into the surf, after which they are slowly drawn to land, the first (drum) seizing them as they pass through the water. It is said that the catch of drum in this way is frequently so large that there is a good deal of difficulty in disposing of them locally in the locality, and many are thrown away for lack of a market” pg 426 Geographical Review of The Fisheries – Maryland: Saltwater fisheries. The Fisheries and Fishing Industries of the United States – by George Brown Goode, Section II for the year 1880 Washington GPO 1887.” Drum is frequently mentioned in the historical literature as a serious predator of blue crabs.
Habitat Change Is Evident In Some Areas
Recent hurricanes have dislodged a tremendous amount of organic matter, which sent downstream in high heat kills eelgrass and covers estuarine shells. It is sulfur-rich and termed Sapropel. Long periods of a negative NAO pattern tends over time to remove Sapropel deposits; a setting the stage for the cycle of eelgrass [Note although much has been written about the importance of eelgrass to blue crabs, some of the best blue crab catches for the Chesapeake occurred when eelgrass populations were low, I suspect estuarine bivalve shell cover to be just as important to blue crabs in the Megalops state as eelgrass meadows which at night can shed high temperature toxic sulfide compounds.]
Eelgrass seems to have its own habitat clock and the sandy-“clean and green” eelgrass has cover (structure) benefits to Blue Crab Megalops but at the end of long hot periods eelgrass tends to collect organic matter buildup and assist sulfate reduction “the brown and furry” eelgrass, a strong negative factor to Megalops’ survival. A better indicator may be habitat stability followed by warmth, such as New England recently experienced. The past decade New England has seen some outstanding blue crab years but regulations have remained basically unchanged for a century. Something occurred here that made habitats better for blue crabs when eelgrass populations were still very low. The last major die off of eelgrass in New England started in 1982 opposite the increase in Blue Crabs.
The predator-prey relationship has also been mentioned regarding red drum, also a significant factor and recorded in the historical literature. In an effort to protect oysters from drum accounts include placing of brush occurred here to protect oysters around the turn of the century in western Connecticut. In 1828 several Connecticut Captains took “natural bed oysters from the Saugatuck River, and planted them between two hummocks near Keysers Island (called Manresa today) South Norwalk. These men planted bushes around the oysters to keep the Drumfish from eating them” pg 122.
Annual report of the Bureau of Labor Statistics of the United States Vol 5, Part 1, 1889.
The Drumfish mentioned is most likely Black Drum listed today as an exotic species by CT Dept of Environment and Energy. A specimen however over 15 lbs was caught off the New Haven Breakwater in 2001. In southern waters black drum is a serious oyster predator at times comprising 30% of diet (Brown et al Estuaries and Coasts Vol 31 pages 597 to 604). The reference of the extent of the protection by this effort leads me to believe that it was warmer then – 1820s as Drumfish must have been so prevalent as to cause such a concern.
Predator-prey relationships also tend to follow life cycle changes - that appeared with oyster culture and starfish in Long Island Sound.
Cold weather over time appears to be the largest factor and why so many times limits on catches just no longer work- (recent case of the lobsters in Connecticut) and in the face of declining resource abundance management efforts tend to protect or conserve reproductive capacity while habitat capacity is often overlooked. Most likely the best example of this is the spawner sanctuaries set up in association for oyster culture in Connecticut a century ago.
When oyster sets started to fail in the 1920s, the oyster industry here sought to place “spawners” on cleaned areas to increase reproductive capacity. This effort expanded in the 1940s as temperatures continued to cool (especially after 1931). This excerpt is from a 1953-1955 State of Connecticut Shellfish Commission Report, page 4, under the section titled, “Spawning Beds:”
“Report of the Shell-Fish Commissioners - Spawning Beds
During the period from July 1, 1953 through June 30, 1955, the program of establishing spawning beds, as described in the 1950-1953 report of the Shell Fish Commissioners, was continued.
After investigation and field tests by Dr. V. L. Loosanoff, Laboratory Director of the U.S. Fish and Wildlife Service at Milford, Connecticut [now NOAA], and through the cooperation of some of the oyster growers who supplied the spawners and the labor, new spawning beds were established in the following areas :
West Haven—in the Cove River, located just westerly of Bradley Point
Milford – in the Wepawaug River
Southport – in the Mill River
The Shellfish Commission [State of Connecticut] sincerely hopes that the public will respect these spawning beds, since it appears that they offer the major hope of revitalizing the oyster crop in the State of Connecticut.”
Although the aquaculture industry supported the oyster spawner sanctuaries, they did not over time prevent oyster set failures. It was gradually getting colder and storm frequency and intensity increased.
The best oyster sets now occurred in salt ponds where warmer temperatures created habitat refugia, of warmer waters. Although the concept of spawner sanctuaries continued for decades oyster sets still declined for decades. Having sufficient oyster spawn in the waters is often not enough – habitat conditions need to be “just right” – clean, shell surfaces with warming waters that follow a mild winter. The 1950s and 1960s were known for long periods of habitat instability; sharp differences of hot than cold, quiet and then extremely stormy. Many seasons’ oyster spat arrived too late for planted oyster shells or froze in severe winters. When you look at the blue crab/oyster landing statistics, they tend to follow each other.
In the absence of habitat quality information pollution and overharvesting are often offered up as logical reasons for resource declines. While the simple fact was gradually the climate was turning against the oyster and oyster fishers as well. The problem is the expansion of the oyster industry occurred during a period of immense pollution and very hot weather (1890s) and it collapsed in cold (1960s).
Blue Crab Habitat Expansion After 1998
Long Island Sound perhaps is a good place to examine this habitat refugia concept for blue crabs. I was very much surprised by the recent surge in blue crabs here recently and historical records do indicate a large-scale habitat reversal even in New Haven Harbor itself. The only difference is being so far north we need long periods to see large changes in abundance. Southern areas perhaps not so much – more Southern areas have shorter time periods, as heat perhaps is not that much of a factor. Perhaps predators have larger roles in southern areas. Energy also is perhaps a negative factor for the smallest blue crabs, as estuarine shell and vegetation also reverse in long cycles. Adults might be able to withstand high energy colder cycles better. More recent examination of sulfide formation in low oxygen marine soils appears to govern Megalops sets as extremely hot may be just as important as extreme cold. Combined with all these factors it is most likely “natural” to have large changes in blue crab abundances. When you examine the historical Blue Crab literature you see that mentioned many times.
Fishery managers tend to stay within the traditional management techniques but habitat quality, environmental quality and predator prey ratios are extremely difficult to address (Special Report #4, 2014). That is why it is necessary to take a step back, so that the picture can take a much larger, broader view. Storms and temperature with overlapping habitat clocks for habitat quality (and of course predators) fills in many biological blanks for the reproductive analytical management models.
Another basic premise that has plagued fishery management models is habitat stability, most of the models assume or assign a fixed value to habitats, (such as the eelgrass issue) but as fishers already know habitats are not stable long term, they change eelgrass meadows come and go and with them their habitat services. Prey species increase or decrease (many respected biologists have weighed in on the dramatic increase in Maine’s lobster catches recently noting that Cod a known huge predator of lobsters is at “historic” low population levels). Temperatures and organic loading (from humus as well as natural sources) change estuarine marine soil pH and the turbulent 1930s and 1940s decreased habitat quality for the soft shell clam sets. Estuarine habitat quality impacts population levels.
One of the best papers on the Internet that describes these early habitat quality attempts is a monograph bulletin titled, “Back Bay” / Currituck Sound Data Report Introduction and Vegetation Studies Cooperative Studies 1958-1965 compiled by Bureau of Sport Fisheries and Wildlife, North Carolina Wildlife Resources Commission Virginia Commission of Game and Inland Fisheries.
The report describes observations of duck hunters and the habitat succession of grasses in part with observation of storms, salinity and flushing rates. Grasses would come and go and so would the population of ducks. We now know for example the eelgrass declines of the 1930s was devastating to Brant but that other grasses favored other species.
If you are interested in environmental history, this report is one of the most comprehensive I have found. It is on the internet. “Back Bay-Currituck Sound Data Report” subtitles “Introduction and Vegetation Studies.” This 1964-1965 report includes Currituck Sound references dating back to the 1820s, providing an environmental history relating to inlet modifications (energy pathways), salinity changes and changes in dominant species – a habitat reversal noticed by researchers and duck hunters.
When ocean water exchange increased in Currituck Sound, higher salinity species became dominant; when exchanges declined, fresh water species reversed. This is a quote that describes this process; found on page 5 of this report:
“Weiland (1897) in a paper aptly entitled “Currituck Sound, Virginia and North Carolina – A Region of Environmental Change, “ stated: ‘One of the most important geological changes which has taken place along the Atlantic coast in recent time was the closing up of the Currituck Inlet, North Carolina, by drifting sands in 1828. Previous to that year this inlet formed such a passage from the ocean through a narrow outer beach into the waters of Currituck Inlet to Pamlico Sound now. With the closing of the Currituck Inlet there was the conversion of upwards of one hundred square miles of shallow salt to brackish water area to fresh water; and it is within the memory of men now living that the resultant changes were immediate and striking.
Previously the sound had been a valuable oyster bed. Within a few years the oysters had all died out and their shells may now be seen in long rows where they have been thrown out in the dredging for a boatway in the Coinjock Bay, a southwestern extension of the Sound. Further, there were such changes in vegetation as brought countless thousands of ducks of species that had been only occasional before. The salt water fishes were driven out and fresh water fishes took their place.”
Throughout the report references to dredging casting up buried oyster shells (reefs) providing direct evidence again of long ago habitat reversals. This is a long report, over 150 pages, but well worth the time. The region has a fascinating environmental history and this report was compiled during the 1960s, a time of great energy (numerous coastal storms) and colder winter temperatures. I found a few references to blue crabbing and close to any inlet, most likely have some excellent blue crab habitats. Although, the 1965 report focused upon the decline of ducks (hunting), which many areas along the eastern seaboard experienced; mild winters also improved habitat capacity for waterfowl as well – when winters turned more severe duck hunters noted the changes.
Anyone interested in the transition of grasses or habitat types will find this report to be of interest – and such excerpts describe the changes in habitats tend to exhibit over time.
For Connecticut continued cold may reduce the blue crab population, but will it increase the lobsters? Only time and observations will tell, at least we might be able to better follow the habitat conditions from now on. The fishery management aspect of a habitat driven Megalops set has so often a target or threshold biomass (stock assessment) that is determined with no apparent connection to a habitat quality or habitat conditions needed to fulfill it.
Observations therefore could help answer some of these blue crab habitat questions. Certainly by mid-June a clearer view of the 2015 blue crab season in the northeast should be apparent.
All observation of blue crabs are important as they add to a long-term habitat history.
Email your blue crab reports to: email@example.com. 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 firstname.lastname@example.org
The Sound School is a Regional High School Agriculture Science and Technology Center enrolling students from 23 participating Connecticut communities.