Thursday, July 18, 2019

Pond Life 3 - The Blue Dasher


Blue dasher, male
This is Blue Dasher Week at the pond. Their numbers have been building for weeks, but now the air is filled with them. 

Nearly 30,000 lenses make up its compound eye, the dragonfly a 360-degree field of vision.

On the fly
Dragonflies can fly forward at about one hundred  body-lengths per second, and backwards at about three body-lengths per second. They are also capable of hovering in the air for about a minute.

With Yellow iris (Iris pseudacorus)
Males protect their shoreline breeding territories. They rise up to investigate intruders, chasing away other males.

Blue dasher, female
Females usually perch on upland vegetation and approach the water only when they are ready to mate.

Depositing eggs while hovering
After mating, the female oviposits her eggs by dipping the tip of her abdomen onto aquatic vegetation.

A vacated nymph case
Most of the dragonfly's life will be spent submerged in a larval stage.  Dragonfly nymphs are fierce predators. Their diet includes other aquatic larvae, small fish, and tadpoles.

An emergent adult with nymph case
Most of the Blue dasher's life is sent in the larval stage where it molts from six to fifteen times over the course of a year or two. In the early hours of a summer morning it crawls up out of the water onto a firm plant base to molt one last time, emerging from its old skin as an adult with functional wings.

The new adult spreading its wings
Although distinguishing species pattern markings are not yet apparent, this new adult is almost certainly a Blue dasher. It flew away within an hour.

The 'obelisk' position
On warmer days Blue dashers raise their abdomens a vertical 'obelisk' position, like a handstand, apparently reducing heat absorbance.

A water lily perch
They hunt by keeping still and waiting for small insect prey to come within range, then darting out to catch it.

Blue dasher on pickerelweed flower
The science of dragonfly flight
When hovering, the dragonfly's wings stroke back and down independently in a kind of rowing motion that creates vortices of air and upward drag. Complex fluid dynamics are instrumental in keeping its body stationary. The efficiency of the wings is increased by their capacity to flex and twist with the air. This natural action conserves energy that the insect would otherwise have to use to effect such turns by exercising muscles. The wings in the foreground also show a solidly colored (dark) cell called a pterostigma,  which by its slightly heavier construction helps dampen vibrations and assists in gliding.
From the Universities Space Research Association's website.





Thursday, July 11, 2019

Pond Life 2 - The Hunting Heron


This week I watched a Green heron masterfully working the pond's edge.


Its forward-directed eyes give it better binocular vision than most birds for pinpointing prey.


It can dart out of stillness like an arrow from a drawn bow.


It's ready when a tadpole surfaces momentarily for a breath.


After a while the heron changes strategy. It climbs stealthily into shrubbery at the far side of the pond. Suddenly its head snaps forward to pluck a dragonfly from the foliage.


Notice the nearly transparent wings above its beak.


Back on the ground the heron stares into the water with statuesque stillness. Then it dives below the surface to bring up a morsel.


It clambers back onto the rock with the aid of wet wings.


Its victim is the nymph of a large dragonfly species, probably one of the Common green darners that frequent the pond.

 
 

The heron flips its meal around head first for easier swallowing.


The hunter has a complicated beauty precisely adapted to its purposes.






Friday, July 5, 2019

Pond Life 1 - The Resident Warbler


Male Common Yellowthroat
 Meet the thumb-sized proprietor of the wooded wetland, with his brassy voice and dashing mask.

Female Common Yellowthroat
He has livened up the glade since early May. He arrived from Central America a week ahead of prospective brides.


While most of the migrating warbler species search for food in the treetops and move on north, Yellowthroats settle down low in dense thickets across Massachusetts. This one advertises his plenteous domain, "Wichety, wichety, wichety."


Water's-edge vegetation supports abundant meals for an agile hunter of bugs, spiders, and grubs.


Lily pads are there for browsing on occasional forages out of the brushy tangles.




The quick-flitting understory life of the Yellowthroat resembles a House wren more than a warbler, and their out-sized vocalizations are strikingly similar.


The Yellowthroat pair have a nest close by. They tend their fledglings by taking carefully disguised routes to the nest. At summer's end all will fly out of the world of the pond on a southward migration of a thousand miles or two.






Friday, June 28, 2019

The Lobster Boat

A conversation with Erik Ronnberg
Maritime Curator, Cape Ann Museum

Lobstering sloop boat, 1880s 1
Lobstering dory in the Ipswich Bay with riding sail 2
Engine-powered lobstering boats first appeared around Cape Ann in the late 1920s or early 1930s. Prior to that, the fishing was under oars. They rowed standing up, pushing the oars on a forward stroke, looking for rocks as well as buoys. They had to be able to get in close around the rocks when lobsters came in.

Lobstering dory, Cape Ann Museum
Eleven foot bottom length, fourteen feet overall

Inshore lobstering dories were tiny compared to those used in the schooner fleet. They had to be able to step ashore to recover their warp and buoys after heavy weather.

Sandy Bay Harbor, 1970s 3
Clare Waddell was one of several brothers who were local boat builders. His father David had operated a shipyard since the 1890s on Bradley Wharf in Rockport, next to Motif No.1. He even launched schooners there. About 1950 Clare moved the business up to his house on Cove Hill, where the Sally Webster House is now. The boats he was building by then were smaller and could go out of the shop on a trailer. When my father made a model of a lobster boat during the 1950s he may have visited Clare to get dimensions and look through the pile of construction molds that were lying around in the back yard. As kids Johnny Buckholzer and I used to play around in those things.

Lobstering boat interior 3
During the 1960s my father had the Rockport Marine Center on Tuna Wharf. He sold gas to the lobstermen. They were always in the shop, talking about this and that. I had some good close-up looks at those boats.

Erik Ronnberg working on a model of a lobstering boat
Cape Ann Museum, July 2017

Here at the Cape Ann Museum we wanted to have a finished model of a lobstering boat on display. Since 1980 we'd been storing one started by Herbert H. Court, which came to us from the  defunct Gloucester Fishermen’s Museum collection. As I worked on completing it, it and I were “on exhibit” in the Maritime Gallery.

 
At this point the companionway into the fo'c'sle needed to be changed. It has to be on the opposite side from the hauling winch and the steering wheel, which should be developing to the starboard. That's because when you're going to pick up a trap, one man has to be able to do the whole job of steering the boat up to the buoy, catching it with the boat hook, running it through the snatch block, and taking it around the winch head. It's all got to be right there at hand.

 
It doesn't yet have a prop guard, but it will. It's a ring that will enclose the propeller to prevent any pot warps from fouling the propeller. With all this turbulence, if there's any slack in the line, propeller suction will draw the line to it. I don't know what's worse--cutting the pot warp and losing 50 pots, or getting tangled up and not being able to get loose from the whole thing. Then he better call the Coast Guard.


He'd had a little cross bit here, but in all my photographs there's nothing back here, not even a stern chock. Of course there has to be a ring bolt for the aft mooring line. The important thing is that it be low profile, so that when you pile traps back here, it's not in the way when you give them a shove over the stern into the drink.


I decided on fitting her with the automobile-type steering wheel that became popular later in the period. Also the deeply-grooved winch that came to replace the long slender ones, where you had to take several turns around the winch head.


I wanted to give her a riding sail. They're not so common now, It was usually mounted off-center, just inside the coming. The interesting thing is that the sheet block for that was on the transom. Again, nothing on the deck. Then the sheet came through, probably to a cleat right on the mast. Very simple.

With a riding sail, you can come up to windward to pick up the buoy. It's a steadying device to keep the vessel from slopping around, strictly for controlling motion, pushing the stern off as you approach the buoy. It wouldn't have much effect on propulsion.


Of course the bottom is coated with standard red copper anti-fouling paint. The other colors are personal choices. It's important to stay away from model colors "out of the bottle." They're too bright, too pure, too clean. They don't take into account the fact that distance, and the intervening atmosphere, mute color perception. Additionally there are weathering effects, wear and tear, and metal corrosion to consider. Painting a model is a subtle business. Otherwise it looks like a toy boat.

Sources
1. Engraving from "History and Methods of the Fisheries," The Fisheries and Fishery Industries of the United States, ed. George Brown Goode of the Smithsonian Institution, 1887.
2. Martha Harvey photograph, courtesy of the Annisquam Historical Society.
3. Erik Ronnberg photographs




Friday, June 21, 2019

An Inshore Lobsterman's Year in Review

Before leaving Peter Prybot's memoir Lobstering off Cape Ann, please enjoy some excerpts from the chapter "An Inshore Lobsterman's Year in Review" accompanied by my illustrative photographs from Halibut Point.

Spring

            By early April the first diatom bloom occurs, and millions of microscopic green glittering primary producers briefly turn the navy-blue waters of winter green, only to bust by a combination of being grazed upon by zooplankton and depleting the nutrients in the water themselves.

            Then knotted wrack or rockweed, Ascophyllum nodosum, "goes spawny" along the rocky shoreline's intertidal zone. During this roughly month-long process, which usually begins in mid-to-late March, the algae's olive-colored fronds turn a slimy brown, and their tips' yellow receptacles first swell up and then break away, soon releasing gametes for the future generations.


            Animal harbingers catch my eye, too. Late March is announced by the white specks of once-planktonic barnacle larvae suddenly settling on new fixed and floating homes--especially buoys, traps and rocks.

            Suddenly catching good numbers of two- to five-inch-long rock eels and cunners in the traps again also tell me it's spring. These fish then move inshore and become active again....A bottom water temperature above fifty degrees Fahrenheit, often felt in May, seems to trigger the cunner movements. Usually the spring lobster run is not too far away.


            The final spring harbinger, the April departure of most of those cute but pesky and pilfering harbor, grey and hooded seas to more northern waters, is welcomed by Cape Ann lobstermen. Some three hundred seals winter on the Big and Little Salvages, the rocky outcroppings and ledges about three miles off of Rockport.

Summer

            Much happens between this season's June arrival and September departure. The marine ecosystem's productivity machine makes hay while the sun shines under ideal conditions of abundant light, food and warmth. Flora and fauna grow, build up their body reserves, and multiply as new generations hatch and old ones die.


            Other lobstermen, along with recreational fishermen and boaters' activities on the crowded inshore grounds, cause tension, too. You often then get set over by other lobstermen's gear, making it hard to pull up your traps. Fishing inside this time of year can get to be downright "seagull," as everyone vies for the tight inshore grounds, much like seagulls diving for food on the beach.


            Another late summer biological occurrence, the shoreline, coves and harbors teeming with huge schools of migrating two-to-three-inch-long menhaden or pogies....These silvery fry hug the shallows, sometimes swimming amongst the rockweed at high tide, in a vain attempt to escape predators like voracious pollock, mackerel, bass and bluefish.

Fall

            Early fall's high activity slows down dramatically by its official December 21 end. The surface water temperature often drops to the mid-fifties by the end of October, and the forties by December. The thermocline in the water column gets closer to the bottom as the cold works its way down....The fall shoreline often thunders with pummeling surf and waves.

            The dinoflagellates bloom in the fall and fire up the dark ocean. The movements of swimming fish and passing boats agitate these top-shaped single-cell microscopic organisms to luminesce.

            The catching of warm-water fishes--triggerfish, filefish, sea horses and scup--in lobster traps signals early fall. Offshore storms and hurricanes usually drive thee Cape Ann rarities into northern waters either from the Gulf Stream or up from the south.


            Early fall's inshore waters become "very active" with bluefish and striped bass as they feed, fatten and group up in preparation for their imminent southward migration. Most of the time, these fish leave Cape Ann waters in early October.


            The skies becoming peppered with vacillating flocks of migratory eiders, old squaws and scoters is a traditional September through November harbinger. These birds fly head on in great numbers, often just above the waves when the wind blows northeast. Majestic gannets move south about the same time, then are frequently seen dropping out of the sky, plunging into the ocean's surface like arrows after fall-fattened mackerel.

Winter

            Winter ends the annual seasonal cycle. The water, like the creatures that live within it, usually rests; just surviving is now the name of the game. Except when agitated by waves, the ocean water becomes very clear, sometimes down to a depth of over fifty feet. It also becomes uniformly cold or isothermal from the surface to the bottom, often hitting thirty-four to thirty-six degrees Fahrenheit. The lowest light levels and (usually) the coldest air and water temperatures slow down nature's production machine to a near halt except for the spawning activities of cod, winter flounder, herring and northern shrimp.


            By early winter the lobsterman's mind is working on relaxation despite being enveloped by this season's early-on gloom and doom ambiance created by the short days and dark mornings. I still feel pressured to earn as much as I can then, knowing the holidays and tax time are just around the corner, and every little bit helps.


            "Do I go, or don't I go?" I make this decision at home by first listening to the weather reports and then looking at my weather instruments. If there's further doubt, I'll step outdoors, glance at the tree branch movements and listen to the sound of the ocean before going to the wharf. Most of the time I'll go, preferring to get my work done early. If the ocean is too rough, you can always turn around and come home. Many other lobstermen make their last-minute decisions from their warm pickup trucks at their favorite ocean observation spots. The truck heater feels awful good on questionable days.