CTFishTalk.com: Megalops #5 Blue Crab Questions Feb 22-16 - Tim Visel - Connecticut Saltwater Reports ( CT Saltwater Reports ) - A Community Built for Connecticut Fisherman.

BlueChip

The Search for Megalops
The Sound School Regional Vocational Aquaculture Center
Blue Crab Research in Long Island Sound 2015
You Do Not Need to Be a Scientist to Report
September 17, 2015
Tim Visel
View Megalops Reports on BlueCrab Info™ Northeast Crabbing Resources Thread
2011 to the present
Report #5

Follow Megalops reports on the Blue Crab Info™ Northeast Crabbing Resources. IMEP fish habitat reports can also be found on the CTFishTalk™ “saltwater reports”.

• Introduction – Blue Crabbers Questions
• CT River Blue Crab Fishery Fails
• Pockets of Crabs Exist in Habitat Refugia
• Western Long Island Sound Habitat Failure – Year 4
• Connecticut’s Green Crab Explosion – Ceondice Johnson

Introduction
For most Connecticut blue crabbers many will agree that this summer was a tough one. There were a few isolated pockets of dense blue crabs, but they are in habitat refuges- gone are the waves of crabs at night reported by striped bass fishers in 2010 and 2011. Crabbers who found these pockets of crabs had some good catches. For many crabbers who started in 2010-2011, the usual great spots were disappointing and at times absent of all blue crabs.

Blue Crabs last fall had retreated into those areas that held on to critical habitat quality factors – few predators, warmer temps and saline conditions. Some questions have come in about overfishing- no, it was not. In 2011 at times we have three waves of Megalops sets; we have good regulations nearly of these crabs perished by leaving the rivers for the deeper Long Island Sound in the fall. Most ended up as food for stripers and tautog. Tens if not hundreds of millions were consumed by Black Sea Bass offshore waters – Connecticut’s blue crab grave yard.

What happened? It got colder, much colder: our Megalops sets were delayed until very late and strong storms increased habitat instability; rains washed tremendous amounts of organic matter into our estuaries. We are in a habitat reversal after three years of colder winters and blue crabs that thrive in hot, quiet times were killed by predators, starvation and sulfide purging from these long cold winters. With reduced Megalops sets to rebuild years’ classes, the crabs “ran out”, and catches and catch rates decreased. With short lived species such as the blue crab – habitat changes (negative or positive) can be seen in just a few years. We are just seeing this now.

I want to thank all those Megalops reporters who sent in detailed descriptions of habitats this summer (some multiple pages). They have been most helpful in assessing the habitat changes now underway. Many have mentioned Sapropel, the black slippery leaf compost – Some areas are now buried in organic matter and were once good “crab spots.”

Two most common observations can be divided between east and west. In the west, 2010 – 2014, productive blue crab habitats are now soft or leaf-filled (especially the Saugatuck) and in the east, some previous soft areas are clean, but cooler. Most eastern CT observations include increase in spider crabs and at times early spring green crabs. That has happened here in New Haven last summer (see last section).
The outstanding crabbing that has been most discussed in the Connecticut River- Essex area is after a decade of great blue crab seasons gone; the crabs never arrived in Essex, and the CT River blue crab fishery has “failed.” (As of September 14, 2015).
Look for blue crabbing to improve or hold till later September; all blue crab observations are important as we learn more about blue crabs in CT.

Please email any blue crab reports, especially of changes in habitat conditions to: Tim.Visel@new-haven.k12.ct.us

Thanks for all the reports

Blue Chip
(Tim Visel)

Pockets of Crabs Exist – Habitat Refugia

Connecticut’s blue crabbing improved in Central CT in late July as crabs’ left refugia habitats and spread out into more saline waters. The best crabbing again was from New Haven to the Connecticut River, but was much reduced from recent years. Blue crabs have yet to appear in Essex (September 15) which is about five weeks later even from recent previous summers. Crabbing was better in lower rivers in the center of the state as catch rates reached 5 crabs per hour for about 4 or 5 lines. This is a level reported to be more consistent pre 2001 when blue crab populations first started to rise- three years after improved Megalops sets in 1998. Large numbers of small 3 to 4 inch blue crabs appeared mid to end of July and if no storms occur, they will reach legal size by the middle of September.

For crabbers that fished in deep saline holes close to Long Island Sound and found pockets of dense crabs, these same areas are found to hold over winter populations some good crabs catches were made. These areas are frequently termed “habitat refugia” when habitat failures happen. An example of this could be cooler waters that held lobsters the longest in warming waters, as such eastern CT held its lobsters (and showed lower incidence of shell disease) and as the cooler pockets of waters slowly ended, lobsters moved to deeper waters if they could. But these areas remain small and few in number; a fourth cold winter may eliminate these last remaining survivors.

Western Long Island Sound Habitat Failure -Year 3

When the 2011 rain events hit Connecticut, I was suspicious of the potential organic matter leaf fall impacts, but at the time thought it might be just a few weeks- low salinity, light covering of organics would stabilize and habitats would soon bounce back. That did not occur for the blue crab one of the species who likes the “edges” not fresh and not full salinity, but the estuarine salinities, the great tidal mixing bowl between the sea and land. This rainfall was a habitat changing event. Temperatures were in range also salinities improved but overall habitat quality did not. The land had with rainfall delivered an unwanted gift millions of tons of organic matter, tannic acids and acidic brown water from mostly leaves. It was however more than a few days event: the organic matter (mostly leaves) swept downstream and was vastly underestimated. I have been telling some crabbers it was as if 6 feet of compost was dumped on a front lawn, it would take years for bacteria to slowly consume it, releasing nutrients into the soil below. I think the western part of the state is more susceptible because most of its salt marshes were filled in over a century ago and they act as a sponge for direct terrestrial organic matter deposition- that important buffer is now gone. [It is frequently stated that the loss of these marshes was from careless development but many marshes were filled between 1900 and 1916 because of malaria outbreaks then associated with mosquito vectored diseases. In many cases salt marshes were filled to obey emergency public health directives. When the heavy rains occurred in 2011 leaf matter was washed directly into estuaries and settled out in areas that just a few days before held hundreds of thousands of blue crabs. Although many salt marshes attribute their formation to the deposition of algae, more current studies show very inconsistent formation- pulses of organic matter (those with “tannin signatures” from tree leaves) show that they were influenced more from land organic matter delivered in floods or heavy rainfall events. That habitat history continues today out of sight but observed by many river blue crabbers. They can see the leaves and at low tide in low wind conditions millions of streaming “bottom bubbles” as Sapropel expels toxic sulfides. I talked to a few New York crabbers several years ago about the Hudson River blue crab fishery. I have most of the New York state reports on the blue crab resurgence in the Hudson River. Since 2004 the crabbing improved in the Hudson, a relatively dry period and the salt water wedge extended far up the Hudson. Crabbing now occurred into at times with the yellow perch (some CT River crabbers noticed this as well). Then it seems as quickly as it had increased, crabs seemed to “drop off” up river and I suspect increased snow melt gradually pushed the crabs back and heavy rains also delivered heavy organic loads – mostly ground up leaves fishers called on Cape Cod, “oatmeal.” This material over time rotted and changed habitat conditions in low energy areas.

The Connecticut River Blue Crab Fishery 2006-2015

This is a brief description of observations of Blue Crabbing between Falls River and North Cove, Essex Town Dock. It follows the dramatic “Blue Crab Explosion.”

Based upon 4 crab lines – hand pulled box traps and crabbing observations
2005 Will Visel at Falls River mouth North Cove 10 to 20 crabs/hour
2006 Will Visel with William Schneider Essex Town Dock 15 to 25 crabs/hour
2007 Will Visel with William Schneider CT River Essex Dock 40 to 80 crabs/hour
2008 Estimated at 20 crabs/hour in August Essex Dock
2009 Will Visel with William Schneider CT River Essex Dock 20 to 30 crabs/hour
2010 Will Visel, Dave Krug, Josh Doyle CT River Essex Dock 90 to 100 crabs/hour
2011 Megalops Reports Essex Dock Observation peak July 8 to 12 crabs/hour
2012 Megalops Reports Essex Dock observation peak August 60 to 90 crabs/hour
2013 Megalops Reports Essex Town Dock (2 to 4 crabs June) 10 to 30 crabs/ late September
2014 Megalops Reports Essex Town Dock (3 to 4 crabs August) 10 crabs/September-October
2015 Tim Visel Observation ( 0 crabs August) As of September 15, 2015 -0 crabs mid-September (and no Megalops reports).

What happened?

The warm to hot summers that followed by cold winters also worked against these crab habitats displacing quicker more efficient compost reducers that use oxygen by much lower sulfur reducing bacteria with deadly toxic impacts. Most home or master gardeners know how important it is even to “turn” terrestrial composts letting “oxygen in for soil microbes” – those microbes are bacteria and exist with other organic grazers such as worms etc. But in the upper Hudson River and in the lower Connecticut River, leaves which became compost just sat and rotted and in heat seeped sulfides, a toxic compound that is a byproduct of sulfur reducing bacteria. This marine compost (humus) was used by coastal farmers a century ago to help replenish soils. One of t he largest harvest areas was in fact, Essex Connecticut North Cove. Such compost however harvested had high amounts of sulfuric acid. This was “the result of exposing this oxygen depleted compost to oxygen again and sulfides turned acidic (sulfuric acid). The farming community learned by trial and error and advice by New England Agricultural Experiment Stations to add bivalve (oyster) shell to neutralize this “hurtful acidity”. Farmers in Maine also utilized the compost and found that lobster shell was a good substitute. This article which appeared in the past New Monthly Magazine in 1880 was reprinted by Li Berliasky Books – “Fish and Men in Maine Islands” written by W.H. Bishop, describes the use of (Mussel Mud) Sapropel by coastal Maine farmers (1880).

“The principal crop, as in the State of Maine, in general was hay. The Deer Island farmer thought it would be double all the others [crops] put together… He put on his lands a top dressing of the refuse from the lobster factories and also “flats mud”, which he found excellent.”

While the farming community had learned about this compost “hurtful acidity” on land in coastal coves when Sapropel is turned by storms causes a dramatic and deadly pH drop killing sensitive larval farms. Accumulations of this leaf compost can emit deadly low pH washes for years and in winter purge sulfides. In areas that obtained heavy flows of organics that have slow river currents, Sapropel can be deadly for years.

In reviewing some of the Chesapeake Bay Blue Crab reports after Hurricane Agnes. Some blue crab habitats took two decades to recover, some apparently have yet to recover. I believe that is happening in CT now: how long will it take to have natural bacteria consume all this leaf compost? I ask this if someone dumped six feet of compost on your lawn (if you had one) how long it would be before you could see your grass again? It would be years! In the marine environment in heat and low energy (no compost turning) it could take decades. In this time, sulfur reducing bacteria could purge sulfides and low pH sulfuric acid events for years after storms for example. Habitats that once seemed to support various forms of life, now become a quiet region devoid of much life, some crabbers have seen sulfate digestion of compost as bubbles of gas coming off such deposits. On September 14 I observed millions of bubbles comes off the bottom in storms by the Essex Town Dock, a small sulfide event was happening locally killing– a few dozen bunker (menhaden). It is difficult at times to describe how toxic these deposits can become after all leaves are natural and sulfate digestion is a natural process but in high heat and low energy such habitats can become very deadly and kill larval forms out of sight and without notice. Crabbers return often to once productive areas finding little life and after awhile stop trying. That I believe has happened in western CT. It was not overfishing, but a habitat failure that has also now occurred in many central Connecticut habitats as well.
Not only can this compost emit sulfides, it can also under the correct conditions shed ammonia and have a very alkaline surface when disturbed emit low pH washes. Sulfur reducing bacteria naturally complex heavy metals especially aluminum and can shed at toxic concentrations killing juvenile fish.

The power of sulfur reducing bacteria to bind heavy metals has been known for decades. The EPA did most of the pioneer research over using them to help bind heavy metals in mine wastes (Tabak et al 2003). In Europe, Sapropel rich in sulfur reducing bacteria (SRB) has been used to clean up heavy metal spills in the environment. Sapropel is used as a soil supplement natural fertilizers and yes, even at times to replace necessary soil metals leached by acidic rains. Connecticut farmers had used Sapropel up until the 1930s. Mostly harvested from rivers the New Haven Experiment Station would test if for farmers until the 1930s.
As more and more information comes in regarding climate change, we will see a shift in population dominance and types of bacteria. This has huge consequences for our finfish and shell fisheries in shallow warm (but not hot) habitats as they become deadly in high heat composting situations.

I appreciate the opportunity to post similar bacteria/nitrogen these reports about bacteria and habitat quality under the environment and conservation thread of the Blue Crab Forum™. The impact of organic matter appears to have had a lasting negative habitat impact. The river to watch and one that has some articles about damaging leaf deposits is the Saugatuck River here in Connecticut.

When will blue crabs habitats become suitable again—that may depend upon climate conditions, storms and cold to move and reduce Sapropel – heat and rains tend to add more organics to the compost pile. It could take decades and only mapping Sapropel could provide critical finfish and shellfish habitat quality information. We can move it also, by dredging or restoring tidal flaws.
Estuarine core studies 1992-94 of Connecticut coastal coves conducted by Wesleyan University clearly show distinct layers of sand/bivalve not mixed with black facies now thought to that to be Sapropel. Some of these layers may represent tens of decades or even centuries of habitat change or transition.
But the shallows can respond quickly – as these past three years have shown. Such organic deposits also change salinity profiles by restricting tidal exchange. Several New England Harbors when dredged for example, experience habitat reversals back to more saline habitats. Winter flounder often reappear especially if Sapropel deposits are removed by dredging.

Scituate Harbor in Massachusetts is a case history of such habitat restoration after dredging of organic deposits. Winter flounder often return to cleaner sand bottoms. Lake and pond associations also report habitat reversals after dredging many times reversing habitat conditions caused by excessive plant growth feeding upon organic deposits much from leaf falls. They had freshwater Sapropel which was also harvested as a fertilizer.

The future of several coastal blue crab habitats appears to depend upon how deep they were buried by organic debris swept into Connecticut’s rivers by heavy rains from tropical systems.

CT residents may recall a wind driven leaf organic paste covering automobiles after recent hurricanes. What wasn’t readily seen was the impact of such heavy organic deposits washed into our creeks and rivers. Now multiply that by thousands of tons of organic material that got swept into our estuaries, once it’s easy to see new completely natural deposits in high heat could change the habitat profile for many blue crabbers.

I appreciate all observations and comments.

Thank you
Tim Visel

Connecticut’s Green Crab Explosion

Crab Observations of New Haven Harbor During the Summer of 2014 Ceondice Johnson, The Sound School
Capstone Project – The Report of the Green Menace
Green Crab Habitat Observation – Tim Visel

As New England experienced a recent surge in the Green Crab population, concerns have been expressed by those following eelgrass habitats – a direct habitat association has been proposed to eelgrass, however, a blue crab monitoring project, “The Search for Megalops,” found observations amongst a rocky/cobble habitat was shown to be capable of providing significant habitat services to the green crab such as feeding and protection in shallow water adjacent to the Sound School in New Haven, Connecticut - just as significant perhaps as eelgrass*. In Niantic Bay large green crabs were subject to an edible fishery.

New Haven Harbor is primarily a commercial port for Connecticut; an urban center with a long association to sea commerce and a large oyster industry. It is located about midway along Connecticut’s coastline, the harbor resembling a lagoon composite shape. The general north/south configuration makes it very vulnerable to storm damage. Between 1889 and 1904, three large breakwaters were constructed to protect the harbor areas from these coastal storms. To assist commercial shipping dredging, the harbor channel has been maintaining a dredged depth of 45 feet. The main commercial channel is along the harbor’s easterly edge. Outside of the navigational channel the tide range is 5.4 feet and the average harbor depth is about 20 feet. Where I was crabbing is a secondary shipping channel 250 feet south of the public fishing pier, which was the site of my study. At low tide it is only about 2 feet deep.

Much of the westerly side of the harbor has been progressively filled for development. A large construction project for the interstate RT 95 occurred here between 1943 and 1952 and about 30 percent of the west harbor was filled during this time. If you visit New Haven by rail, the railroad station marks about where the pre-colonial shore used to be.

In the 1950s, green crabs expanded habitat coverage spreading north into the Maritimes harming soft shell fisheries. The most recent rapid increase in New England’s green crab population has taken many marine biologists by surprise harming shellfish populations and occupying ecological areas not seen in recent times. The increase in the green crab has been very damaging to New England’s shellfish industries, especially soft shell clams on Cape Cod and in Maine.

*An eelgrass meadow on the east outlet channel of Niantic Bay was found to be capable of providing habitat services for extremely large green crabs which were retained for food. In 2012, several recent New England region articles have proposed putting green crabs on the menu with articles titled, “Should We Eat the Enemy?” –Boston Globe Magazine, February 12, 2015, Roger Warner. The green crab remains a popular food item in the English Channel area. Large green crabs have been considered a delicacy in this region since the Middle Ages. (Tim Visel)

Ceondice Johnson – Study Outline Connecticut’s Green Crab Explosion

Site of Study:
The Sound School is located on Sea and South Water streets and occupies many former waterfront commercial sites of shipyards, marine mechanics and oyster businesses. The immediate study area is the remains of a 19th century sewer canal that now acts as an emergency bypass outfall for storm water. The study, in fact, was conducted at the terminus of the outfall pipe, which has been decked over and serves today as one of the few handicapped accessible public fishing piers. A series of granite blocks were placed to stabilize the area and is today a reef/intertidal habitat profile (placed blocks have been encrusted with seaweed, barnacles and the blue mussel) is also found.

Description of Equipment:
For my study, I used a 2-ring metal hoop trap with a wire mesh net. I used this to lift and quickly trap crabs that had crawled into it. The bait that I used to attract the crabs sat in the center of the trap.

When using a hoop trap, you can use string, rope or twine to raise it up out of the water. You also have to raise the trap quickly so that the crabs do not escape from it. The best places to set the trap are sandy areas, rocky areas and/or spots with high marine vegetation (sea lettuce).

Dates/Times:
I would start in the morning and usually have an 8-¬‐hour day. I started the study on June 26, 2014 and ended it on August 27, 2014. In that time, I noticed a large decrease in population of green crabs by the end of the summer; very few were close to shore. At the beginning when the water was cooler, green crabs were abundant, even into the shallow water

Bait Types
I mostly used frozen menhaden (bunker) that was cut in pieces. I also used (when it was available) raw chicken legs and mackerel.

Bunkers are small, oily fish that don’t get much bigger than 15 inches in length. They are round with oily flesh and have a deep forked tail. Mackerel are small, fast fish with stripes.

The crabs were mostly attracted to the bunker bait. I noticed that the blue crabs walked over to the mackerel and chicken leg bait, stared at it for up to an hour and then walked away, while the green crabs stayed away from it completely, except for one green crab that had only one leg.

Based on my experience with this research project, if I were to conduct the study again, I would stick with just menhaden as the bait.

Observations: When I began in June, I was able to catch hundreds of green crabs each day. By July 3rd, I was only catching 20 green crabs per hour and by the end (August 27, 2014) I only caught one green crab (four hours). From August 18, 2014,

I noticed that as the water got warmer, the less green crabs I saw. I recorded that during this time, the seawater changed from 60 degrees to 75 degrees from late June to August. In the beginning of the project I did catch a few spider crabs.

Conclusions:
From my observations, blue crabs did not arrive / inhabit the same areas at the same time as the green crabs. As water warmed, green crabs became scarce and finally some small blue crabs moved in. The Blue Crabs remained scarce all summer with only a few showing up in August – A large difference from the previous summer.

In June when the green crabs were prevalent, I could catch a full five-gallon pail; some were given to Blue fishermen and one person caught five Bluefish on the green crabs (on bottom hook rigs).

While the original study was to catch and measure blue crabs, what I discovered was immense populations of green crabs living along the Sound School shore. That became the topic of my Capstone presentation.