COMMENT: There have been some pretty negative comments about this article. Please read the supporting documents before you blast off. This is a serious local pollution problem that has been ongoing in the key watersheds leading to St. Mary’s Bay and the two other harbours and may have recently been exacerbated by a collapse of the mink farming industry. If this was domestic pollution, or fracking fluid, or forest spray, or an agricultural dump, folks would be supporting this like crazy. But waste from fur farming is somehow different apparently. As for this being a cause? So far nothing has been identified and high nutrient (phosphates) levels are known to cause oxygen depletion. Whether or not this is the cause and is identified as such depends on someone taking it seriously and, like all of the other possible reasons, checking it out. See: https://en.wikipedia.org/wiki/Eutrophication for more information. AM
I, like many folks out there, have been perplexed by the herring die-offs all on the Outer Bay of Fundy shores of Nova Scotia … principally in St. Mary’s Bay, but also in Digby Harbour and Yarmouth Harbour.
DFO has reportedly done test for the usually viral and bacterial causes for such events … all with negative results so far. Other suggestions have included pollution from Saint John, the newly started tidal turbine in Minus Basin, sprays, fracking waste and even a recent suggestion that it was the mammoth sewage dump up in Quebec. So far the cause seems to be out of reach.
Here’s what we know at this point in time.
- So far the kills have all been in embayments or estuaries,
- The kills are huge but exact estimates are not available,
- Initially, the kills only included herring, but a recent event included starfish, scallops, bar clams, mollusc species, and other invertebrates,
- Each of the kill locations have major watersheds draining into them,
- No other kills have as yet been reported along the other coastline of the Bay of Fundy, along the Western Shore, or in New Brunswick or Northern Maine shores.
- No bottom checks have been reported.
THE HUNT BEGINS
Based on the information at hand, I began to wonder whether this was the result of a shore-based toxin coming in by rivers and streams, but the widespread locations seemed not to support this idea.
So I checked a watershed map and found that all three major areas where kills occurred have large watersheds that have their headwaters in the same general inland area. Bear River and Annapolis River that flow in Digby Harbour, Sissiboo River and Metegan River that flow into St. Mary’s Bay and the Tusket River at Yarmouth.
That led me to a long hunt for possible sources of toxic effluents.
Google maps shows a huge amount of clear-cutting in the common headwaters area. Often the next step to clear-cutting is to spray the area with herbicide to ensure elimination of hardwoods. Well, there seems to be lots of spraying going on in Nova Scotia, but I could find no reference to any in this area. So what else could it be?
Next I checked for fracking activity, but couldn’t find anything for this area. Then it was mines. Definitely a few possibilities there, but they didn’t seem to be well located to affect all the areas and the activity didn’t seem to be intense enough.
Then there was methyl-mercury which is considered to be among the highest in the world in Lake Kijimkoujic and surrounding wetlands. A most puzzling occurrence for sure. So I began researching more on that and in the process of checking out some maps, I ran into a map of the mink and fox farms of Nova Scotia and discovered they are in the greatest concentration in the area I was researching.
MINK FARMS & WATERSHED POLLUTION
Hmmm … then I started digging deeper and was truly surprised at what I discovered:
- Mink farm waste elevates nutrient levels and these wastes are believed to be the cause of serious green alga blooms in lakes, ponds and streams in the area and the accompanying death of fish and invertebrate species.
- Mink farms have huge communal dump sites, but wastes are also dumped in gravel pits, along roadsides and in other unapproved locations.
- The mink market crashed this past year and dozens of farms are in trouble, have closed, or are in bankruptcy. Over 350 jobs have been lost and more impacts are expected.
- The popular black mink variety suffers from a serious viral infection that creates mortality problems. So farmers have been moving to the brown variety and eliminating the black variety. No information on their disposal could be found.
- Dispersal of wastes into the environment is known to occur over an extended period.
As verified by the following map, it is apparent that many of the mink farms, communal dump sites, and illegal dump sites are on the rivers leading to the estuaries or coves where herring have been dying .
Zoom in (++) to view the area from Digby to Yarmouth, NS):
So there you have it. It is clear that mink farm waste has been a problem. But now we have a collapsing industry. What happens to the existing inventory and waste. Are the unsaleable mink killed and added to the waste? If so, could this have created a nutrient spike that caused the downstream estuaries and embayments to become deficient in oxygen to the point where the mortalities have occurred and continue to occur? Would this kill bottom dwelling invertebrates which usually have better tolerance to low oxygen levels?
Fortunately, I was in touch with Debbie MacKenzie, a longtime advocate for the ocean. She mentioned the mink farms as a possible reason for the herring mortalities, among other things, but I basically ignored that because, at the time, I didn’t have sufficient information to realize the extent of the problem.
In any event Debbie suggested the following possible scenario:
I have been watching with great concern the story about the herring . I posted a comment on CBC’s facebook at the start of it, suggesting the following possible explanation:
The swirling Fundy waters tend to surface concentrate floating stuff, and this could create local concentrations of toxic algae. Herring swim in tight groups and come to the surface at night. If they swam through surface concentrations of toxic algae, this could kill them by quickly and physically compromising their gill function (this pathway to fish kill by algae is known in the scientific literature). If the herring were killed in that manner, their flesh would not likely test positive for toxins, nor would scavengers who ate them become ill from toxins.
Enough dead herring could have sunk to the bottom and be sloshing back and forth and by now rotting in St. Mary’s Bay to the point where oxygen-starved bottom water is killing invertebrates wholesale.
So here’s the shorter story:
- Known wastes from mink farms and mink farm closures and other unknown sources add high levels of phosphates to the bays and estuaries where herring have been congregating.
- Damaged gills leads to the death of many herring which drop to the bottom,
- Oxygen levels plummet leading to the mortalities of a wide variety of bottom dwelling marine invertebrates.
- The episodes continue as more herring arrive in the area.
This document is based on 20 odd publications including: public websites, government documents and scientific documents. The principal references are contained in the following PDF.
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