SUMMARY OF FALL 2020 MENHADEN (BUNKER) BEACH STRANDINGS
This last fall, 2020, Menhaden, known locally as “Bunker”, a species of herring and one of the most important, prolific and numerous “forage fish” in the Atlantic has been reported washing ashore dead or dying all along the east coast beaches from New Jersey, Hudson River, New York Harbor, Connecticut and Long Island.
As early as September 2020 the State of New Jersey’s overflights (of the state’s marine environment and beaches) reported masses or “pods” of “bait fish” (Menhaden) observed nearly continuously from Sandy Hook to Cape May on the Atlantic seaboard of that state. These fish, arriving from the Chesapeake and south continued north and eventually entered the sounds, bays and harbors of New York, New Jersey and states further north. But as the “fall run” proceeded these fish became disoriented and stranded on beaches l or died at sea and washed ashore in numbers which raised serious concerns to fishermen, beach walkers and environmentalists up and down the coast.
The die off of this critically important fish species—-known as Brevoortia tyrannus to the fish scientists—has been reported most commonly as “normal” and of little consequence. While others claim the event is related to such diverse and conflicting causes as: too warm sea water temperatures, or sea water too cold; scarce food, low oxygen levels, too many fish this year, overfishing by purse seiners, too restrictive catch quotas placed on purse seiners, too lax quota regulations placed on purse seiners , and the all too common explanation of “global warming”. This latter too often cited phenomenon is that seemingly catch-all cause for everything and anything which permits those who don’t really know the answer a means to wiggle off the hook and still seem “scientific” and knowledgeable. .
For Long Island Sound, the most common and widely published explanation has been that the “unusual warming” of the Sound over the summer season persisted into the fall. This resulted in these filter feeding, plankton-eating fish to miss their “temperature cue” to head south and thus they became stranded in the Sound where water temperatures fell as winter approached and plankton concentrations (upon which these fish depend) declined.
This may seem a logical explanation at first glance, except for the fact that contemporary fish die off have been reported elsewhere, such as along the New Jersey coast, in the Hudson River and along our Atlantic Coast beaches in New Jersey and on Long Island’s Atlantic coast beaches such as Southampton, New York. These areas are not shallow enclosed coastal embayments like L I Sound, and fish were not trapped in these venues or were water temperatures falling so rapidly in the well mixed deep open ocean.
Thus, the causes of the die-off has been poorly and inadequately addressed. Additionally, though many observers have reported fish strandings these are most often simple anecdotal accounts. No actual measurements or other data to put this possibly serious event into an historical or numerical perspective have been reported
The critical question remains. How many of these fish have died? How does it compare with others? Is it local or regional? Is it a serious is threat to the health of this important fish stock? No one seems to know.
As a result of simple curiosity and concern, this author conducted 23 observational walking tours along two central Long Island Sound beaches to count stranded Menhaden and make a rough estimate of the number of fish washed ashore, between Nov 15, 2020 and January 14, 2021.
The results indicate that during the period between mid-November and mid-January, approximately 752 stranded fish were counted per mile on the 23 day period sampled. On average, approximately 33 fish of this species were washed ashore per day per mile during the sample period. See “notes” below for other data.
Attempting to quantify the magnitude of the fish die off in Long Island Sound one could extrapolate from this small linear sample of Central Long Island Sound by calculating total shoreline mileage of Long Island Sound and assuming that circumstances of fish strandings beyond the local beach zones sampled would likely be similar over the length of the entire Sound.
To that end, it is often claimed by the State of Connecticut that its total L I. Sound shoreline from New Rochelle to Groton comprises about 330 miles of beach and Sound shore. Long Island’s shoreline is at least as complex and as long. Thus the total Beach and shore of Long Island Sound (I use here as a rough and likely minimal estimate) may comprise an estimated 330 x 2 or 660 miles of beach and shore.
Thus if the central L I Sound area sampled in this report is in any way representative of circumstances of fish strandings elsewhere in LI Sound, each mile of shore may have had at a minimum 752 stranded fish over that sample period. Seven-hundred fifty (752) fish stranded per mile x 660 miles of shoreline = 495,000 Menhaden fish or nearly one half a million fish washed ashore dead or dying in Long Island Sound.
That number must be a minimum estimate, since over the period of 15 November to 14 January there are 60 calendar days. However, the the study sampled only 23 out of 60 or only 38 % of the total days. Thus the 752 fish stranding figure is likely only a fraction (38%) of the actual total fish strandings. Calculating that the 752 fish represents only 38% of the total (752/ 0.38 = 1,979) we can assume that would suggest that nearly 2000 fish were stranded per mile in the study beaches.
Thus based upon these corrected data, a likely figure my be closer to 2000 fish stranded per beach mile, or 2000 bunker fish per mile of beach or shore may have stranded on Long Island Sound.
Evaluating this another way, The average strandings per day per mile, as noted above is about 33 fish per day per mile. Thus 33 stranded fish per day x 60 calendar days = 1980 fish stranded over this study period—again a figure close to the 2000 stranded fish per mile over the study period.
Using the value of 2000 stranded fish per one mile over the 60 day study period, extrapolated to the 660 miles of shoreline in the Long Island Sound suggests that there may be (660 x 2000 = 1,320,000) or one million three hundred thousand fish may have died and washed ashore only on our own Long Island Sound beaches.
More than one million fish stranded on Long Island Sound beaches, may represent only a small percent of the total estimated stock of these fish, which are purse seined in the hundreds of millions of pounds of fish per year for fertilizer, the fish oil industry and for bait. But when one considers areas others than Long Island Sound, such as New York harbor and the Hudson River, , New Jersey and elsewhere it may indicate that the numbers suggested for Long Island Sound may be a only a small part of the total regional fish loss this 2020-2021 season, which could conceivably go into the tens of millions of fish or tens of millions of pounds. That number then becomes significant when we know that regulators have recently permitted purse seiners to take 400 million pounds of these fish annually.
Given the regional importance of this fish species to the health and well being of the general marine ecology and the health and reproductive capacity of other species such as Stripers and Bluefish as well as marine mammals and birds which prey on fish, with this so far unexplained regional die off we may be facing a serious threat to the health of this important forage fish species and our local marine ecology.
Notes.
[Over the study period, a total of nearly 18 miles (17.94 miles) were walked. Each observational tour was conducted close to the surf zone were the the number of recently stranded Menhaden were easily observed in the surf or stranded on the beach, Only live, dead, and recent stranded Menhaden were counted on each tour. Water temperature of LI Sound was recorded, based on the published data (NOAA or “sea temperature.info”).
Each observational walk spanned a distance of between 0.5 miles to 1 mile in length. Total miles over the study period were 17.94 miles. Counts of recently stranded or live Bunker ranged from 0 fish to 112 fish. Sea temperatures ranged from 53 degrees F on Nov 15 to 41.5 degrees F on January 14, 2021.
These data were extrapolated to a standard mile and tabulated as “Stranded Fish per Mile”/per day of observation. This measure ranged from a maximum of 172 stranded fish per day/mile to 0 fish per day per mile. Fish which were observed stranded alive were counted and recorded. Live strandings were calculated as a percent of the total fish observed for that day. This value ranged from 0%-33%. Total numbers of live fish swimming weakly in the surf or flapping on the beach were small and most often no live fish were encountered. This was likely related to the fact that such fish readily drew the attention of sea gulls, which quickly killed and partially consumed the fish.
A graph of the data (not published here) reveals that strandings were most numerous between mid-November and mid-December when mean strandings per day were 66 fish counted per day. From mid-December to mid-January fish counts fell off to an average of 11 per sample day. LISound temperatures dropped during the initial sampling (the November to December period) from 53 F to 49.3 F, ( or 3.7 F), while it fell from 49.3 F to 41.5 F (7.8F) during the later period from mid December to mid-January.]
Clearly more detailed studies of the factors affecting this species such as possible disease, chemical factors , environmental, human exploitation and management practices which may be affecting the health of this immensely important fish stock should be undertaken by a regional or Federal agency which could most effectively monitor this species which ranges up and down the entire Atlantic coast.
Note: On May 6, 2021, I counted one fresh Menhaden washed up on the beach at Mount Sinai, Cedar Beach. It was fresh and had been partly eaten by gulls.
