An Overview: As we enter the fall months we are faced with some decisions. Decisions that must be made today not tomorrow.
Alewife progeny emigrate from their freshwater natal ponds out to sea for the most part in August and September, when they have reached sufficient size and strength; some additionally in October, and some as late as November, weather dependent. If we do not get enough rain between September 1st and November 1st to provide enough water for the thousands of alewives born this year in Slough Pond to join their brethren and get out to sea we are going to have to help them. Simply put. This decision is up to the Alewife Committee, The Natural Resources Department, the Natural Resources Advisory Commission, and our Town leaders. It is always best to have a contingency plan and it never hurts to plan ahead, without paranoia, fear, or anger, but with the commitment we all share to protecting our wildlife and their habitat; indeed the circle of life. It would be unconscionable to do otherwise. We plan to act on such a request through the relevant channels in the coming weeks.
As I have written here before, decisions that will effect the health of the herring population, the habitat they support, and the entire ecosystem they are part of requires long range planning and the input of knowledgeable professionals, as well as the citizenry of Brewster. This planning will also have to take into account, as much as possible, evolving science on the increasing effects of climate change. The idea of blocking the Walker/Slough passage and sequestering the alewives into three ponds (as suggested by the Committee), that is Lower Mill, Upper Mill, and Walkers, two of which are compromised yearly by eutrophication (when there were seven ponds in the Stony Brook Watershed migration route historically) will have unknown effects, though some may be predictable. Herring need and seek a diversity of nursery habitats to insure healthy progeny. Remember that Slough is the healthiest pond in Brewster. The future effects of climate change on air and water temperatures, sea level rise, droughts, floods, loss of habitat and resources, etc. makes stewardship a complicated commitment that requires flexibility.
As background to the present situation, the decision was made by the Alewife Committee in February of this year, after considering the advice of other professionals, to not close to passageway so abruptly this year as they had intended to. Professionals called for further study. It was decided that the Slough Pond passage would be monitored this year, without providing typical annual herring run maintenance. Sticks were allowed to be removed on one occasion but no digging or erosion control was allowed. Some might argue now that if it had been closed and migrating adult alewives had been blocked from entering this spring to spawn in the pond (as they have for a least a century) we would not be in this predicament; others might argue that if the passageway had been properly maintained this year and in the previous three years - noting the year 2020 was the beginning of the pandemic and also the death of Dana Condit, herring warden for 40 years, followed by the drought year of 2022- we would not be in this predicament either, as the majority of the fish would have been able to get out. Will the thousands of alewife fry born in the Slough Pond nursery this spring become collateral damage to the lack of a realistic management plan?
As it stands we are faced with these consequences. My contribution to 'monitoring" the passage, as an independent citizen scientist/naturalist, having some knowledge of alewives and Slough Pond, has been to document this year's migration on the ground and to raise public awareness. From the data I have gathered it is clear that we are at a critical juncture today.
Still, we are hopeful Mother Nature will intervene as she did for the spring migration with plentiful rainfall. We are also hopeful that our Town leaders and those advising them on the issue of herring management this year perhaps do not know how many alewives we are talking about saving here from a potentially catastrophic ending to this migratory cycle. This is how we raise awareness. We are also hopeful that the October Natural Resources Advisory Commission meeting with returning guest advisor Biologist Brad Chase of the MA Division of Marine Fisheries will help implement a sustainable plan not only for the spring but one that will address the critical issues we face this fall due to decisions made earlier in the year.
On September 1st the gauge at Slough Pond read 0.4". From our data record, this gauge reading generally depicts enough water level in the pond, and therefore the fish passageway, to provide safe levels for the passage of alewife fry, if there is flowing water, which there is not at this time. As we all know, standing water breeds mosquitos, which are abundant presently along the passageway in the woods. Everything is connected.
Video: the daily passage of alewives past our home on Slough Pond.
September 5 The passageway is mostly dry now, though mucky, and with so many fallen leaves it looks more like late fall. It will take some serious and extended rainfall to create a flow of water in the channel again. There is still a good head of water at the Slough Pond entrance however. There is no alewife activity, some frogs present within the area that still holds an inch or two of water (just ahead of the culvert pipe), with lots of mosquitos there as well. The leaf debris will decompose and add to the accumulated sand making clearing the passage that much more work since it has been left unattended for so long.
September 6 Visiting our neighbors today. Bound Brook in East Dennis is our closest neighboring herring run. We visited this serene, beautiful, and well-maintained run last in May. Today the stream was deep and flowing; no alewives, no mosquitos either.
Also last visited in May was the Scargo Lake fishway in Dennis. A great effort was made to restore this fishway which had originally been dug as an irrigation ditch for the cranberry industry along Quivet Marsh and its wetlands 200 years ago. It is now well-maintained with freshly dug out piles of sand along the banks which are heavily vegetated above a low cement wall. It is an actively managed fishway with several weirs along the channel to control water levels. The water was noticeably deep today and slightly flowing. Numerous alewife fry were spotted in the stream, though smaller than ours at Slough Pond, which indicates their youth. A large bass was lying in wait in the shadows of a low footbridge and ambushing them as they passed by. They did not seem to be in a hurry to head out to sea.
And yes, sadly, for the sake of comparison, the Slough to Walker's Pond passageway today looks like a disaster area, abandoned and haunted.
The fish ladder we cherish that runs alongside the Stony Brook Grist Mill may be well managed and picturesque but the same does not hold true for this passageway to one of its natal freshwater ponds- a significant alewife nursery- which is the intent of the ladder after all. Shouldn't the public and private face of stewardship be the same? By all appearances this year the Slough Pond passage has effectively been closed- through continued neglect- contrary to the public decision. Herring management is not easy. Sure, it would be easier to close off this part of the migratory route but is ease what we are after? We hope the Town is open to the partnerships and collaboration on offer to help shoulder the burden of work. As I have said elsewhere, we are all in this together because we care.
September 9 The gauge at the pond landing today reads 0.3" which is quite low. Oddly though, all of us pond dwellers have remarked on how high the pond has stayed this summer, even this week. I measured it at the same depth in front of our house and there is a 3" discrepancy, ours read 6". We have been using the landing gauge as our reference point all summer and will continue to but the difference is interesting.
September 14 Attended the Natural Resources Advisory Commission meeting tonight (agenda on link as well as list of members) and provided an update on the situation at the passageway which can be read here: slough_pond_update_9-14-23.pdf The video of the meeting is also available here, my commentary is at the top of the hour. I believe the Commission to be a very committed group.
September 16 The rain we had hoped for with Hurricane Lee did not materialize though we are grateful it was a mild storm. Brewster received 0.6" in rainfall; the gauge read .39". Walking the passage today we picked up some fallen branches and noted that there is about 1" of water along most of the passageway. More fallen leaves have accumulated on top of those piles already clogging the stream. There was no fish movement anywhere along the passage- too shallow and clogged.
Someone, perhaps the Town, had added some fallen branches of their own ahead of the storm, presumably to fortify the sandbags and provide more runoff control around the culvert area. They were put in place yesterday, the day before the hurricane was due. More sandbags would be preferable. It should be noted that although runoff from the (private) dirt road does effect the herring passage, polluting the water and causing erosion, the sandbags and sticks are on private property that is not directly on the herring run and one wonders if it is acceptable as maintenance without permission of the landowners... Something I will look into.
Meanwhile, the pond is so much quieter now, on its surface. The Mallard flocks are reduced in number closer to their wintering over populations (only three ducklings survived the Snapping Turtles' assaults this summer) but we expect to see a more diverse population of visiting waterfowl soon. The Osprey is rarely seen though the Great Blue Heron fishes daily. The Cormorant still dries his wings on our dock and the Kingfisher flashes joyfully past, but not for much longer. Small flocks of Swallows still circle and dive and the Canada Geese continue to gather at dusk, though their numbers too are vastly reduced. We have turned toward fall with the Autumnal Equinox only a week away. Of an evening, for now, we can still revel in the steady beat and trill, hum and whistle of insects we cannot name, the geese speaking to each other in their own language, the wind in the trees; only the stars are silent moving across the sky and over the face of the pond.
September 17 Good morning alewives! Soon, soon you will go out to sea. Note how they have taken on the color of the sand and how much larger they have grown.
September 19 Yesterday's storm brought the much needed rainfall we'd hoped for from the hurricane. There was a good flow of water along the passage, with depths of 1" -3" and 5" in the deep area just ahead of the culvert pipe. The flow, however, was interrupted in many areas by piles of sodden leaves on top of the sand accumulations. No fish were observed. The sandbags and stick fortifications did seem to block excessive runoff from the dirt road. The gauge at the landing read .54" which is quite high, after 2" of rain Monday, with schools of alewives circling just beyond.
September 20 The gauge reading was .52" this morning, but there was a strong flow of water with improved levels from yesterday in the passageway in most spots. Some areas are still only about 1" deep, especially the stretch past the culvert heading towards Walker's, but the flow was good today. Someone had moved some of the stick fortifications aside along the path, no doubt now that the stormy weather had passed. And it appeared that someone (not me) had pushed the sodden leaf piles aside along the passageway creating little openings for the water to stream past. It did not look natural. Just this small action created a steady flow of water that might very well be enough for the alewives to pass, with some effort in the low depth areas. These opportunities can change quickly, sometimes overnight, so we hope some fish will take advantage of their chance. However, I did not see any activity at all this morning or afternoon. I cannot always be there to observe the passageway so some might of departed. I will keep a good eye on it and also look for the schools in the pond in the next couple of days which is the best evidence of their presence. But Hallelujah...
Three videos of water moving along various sections of the passageway today.
September 21 No fish sightings to report although water is running freely along the passageway. The leaf clearer may have returned as the channel is so clear of leafy deposits that the sandy bottom is predominant in many areas previously clogged. The fact that the water has been running free for three days now may also account for the clarity. The water level at its lowest averages 1.5" or so. There is little wave action at the mouth at Slough.
The water level is lowest along the passage past the culvert, with some debris still present. And though there is a steady flow of water out of the culvert pipe, its edges are ragged and treacherous looking. No one I've spoken with knows when this pipe was installed, but Town records might provide that information. It is certainly old. The stick fortifications, moved off the sandbags the other day, have returned to their original position, and the others along the bend are still in place, though moved by runoff. Rain is in the forecast for the weekend.
September 24 It has been a gentle rain this weekend with little accumulation, nevertheless, water is flowing quite nicely along the passageway with enough depth for the fry to manage. We have not seen any schools in the passageway at all nor have we seen any in the pond since Tuesday. A neighbor did report seeing small schools late in the afternoon on Tuesday swimming down the passageway past the culvert. Recall that Tuesday was the day leaves had been moved aside along the channel creating an open flow of water and there had been a good rain on Monday. Apparently there was also some digging along the passageway by an authorized warden, done in moderation. The fry do not require as much water depth as the adults and there may be just enough between rainstorms for them to depart, with the timely leaf raking and sand digging aiding their emigration. We will keep an eye on things in the weeks ahead. The gauge read .52" today, holding steady from the reading on the 20th.
September 29 & 30 September has been an eventful month, from dry conditions along the passageway, on the 1st, to a restored water flow due to rainfall, by the 19th. Today, on its final day, we are happy to report that large schools of alewife fry entered the passage yesterday morning, the 29th. There has been a consistent flow of water in the passageway with our intermittent rainstorms and the moderate digging and leaf removal that occurred over the past twelve days. The water level is not high, approximately 1.5" - 2" in most sections; the exception being the "ditch" area by the culvert which has maintained a good 5"-7" depth. Hundreds of fry gathered in these depths having run the gauntlet from Slough. Only a few at a time ventured into the culvert pipe.(See videos below). A warden did some additional digging in the early afternoon Friday and within a couple of hours the schools gathered in the ditch had dispersed, hopefully making it into Walker's Pond and eventually down the fish ladder and out to sea.
In the photos below (and the videos farther down) you can see how the fry travel in small groups. This is the section of the passageway after they enter from Slough. They then navigate a small curve that leads to the section heading directly toward the culvert. It is clear in these images how a little moderate sand and leaf removal provided the fish with adequate passage even with low water levels. The gauge at the landing read 0.46" yesterday which is down from .52" on the 24th. Today's rainfall should help with the continued alewife emigration out of Slough Pond. However, the concerns I raised on the 14th are still pressing issues though it is encouraging to see some schools have been able to depart this week with the moderate measures taken and a little rainfall.
Below are three short videos recorded on the 29th showing the migrating alewife fry in the Slough Pond passageway; making their way around the curve, schooling in the deep area by the culvert, and exiting the culvert pipe.
We ventured out in the late afternoon after the rain to see if there were any developments down at the run. There were small schools of fry moving along the passage, not as many as yesterday but still some vibrant activity. Most did not venture any farther than the entrance to the culvert pipe and very few were seen beyond it. The area past the pipe does need more digging out as the water is quite shallow along this stretch with heavy erosion. The fact that it is much wider than the rest of the passage might give the fish pause, if not just entering the pipe itself. They moved up and down the passage, perhaps enjoying the freedom of movement, but not committed to leaving just yet. In fact, some groups swam back into Slough. (See videos below.)
We did come across a dead alewife fry by the culvert who was definitely not a member of this particular emigration group, being larger and more mature. He might have resurfaced from the sandy depths with the digging that occurred yesterday. I recall a couple of floundering fry about his size on August 22nd. Fry can range in age and development from 3 - 5 months depending on their birth date. Recall that the first adult alewives arrived in early April and quickly set about spawning, with various groups continuing through June 1st. The causality was a beautiful fish, bright silver scaled and perfectly formed with no marks of predation or injury on his skin, which leads me to think he asphyxiated at some point in shallow water.
So we wrap September on a high note. We still have time in October and early November to make sure, as much as possible, that the majority of fry have made it safely out of Slough and heading to their life in the sea. There is still work ahead and there are still decisions to make. We will keep you posted.