Managing Ecosystems for Productivity and Resilience: An Argument for Alewives in Maine

An Independent Study in Environmental Studies
By Michael Tillotson
Advised by Professor John Lichter
Bowdoin College
May 15, 2008

Table of contents:

Introduction: 3

Profile of an unlikely hero: The alewife (Alosa pseudoharengus): 5

A fish for any need: Current and historical importance of the alewife: 8

Excess and neglect: The decline of the alewife: 12

A brief digression on the definition of natural: 16

The alewife as a keystone species: 17

Interactions with:

Atlantic cod: 18

Striped bass: 22

Atlantic salmon: 26

American Lobster: A synthesis in the context of Maine’s most important fishery: 31

Merrymeeting Bay: Past, present and future fisheries potential: 36

Conclusion: Managing ecosystems for productivity and resilience: 44

Literature cited: 47

One would like to know more of that race, now extinct, whose seines lie rotting in the garrets of their children, who openly professed the trade of fishermen, and even fed their townsmen creditably, not skulking through the meadows to a rainy afternoon sport. Dim visions we still get of miraculous draughts of fishes, and heaps uncountable by the river-side, from the tales of our seniors sent on horseback in their childhood from the neighboring towns, perched on saddle-bags, with instructions to get the one bag filled with shad, the other with alewives.

-Henry David Thoreau, 1840

Introduction

No dam shall, hereafter, be erected across any river or stream thro’ which alewives or other fish have been accustomed to pass into ponds, in which there is not made and left a convenient sluice or passage for such fish…

­-An Act to Prevent the Destruction of the Fish called Alewives. 1736

Decades prior to the independence of the United States the New England colonies recognized the great importance and fragility of their diadromous fish populations. Over two and half centuries ago lawmakers of the Massachusetts Bay Colony understood the ease with which such fish could be exterminated. While they likely could not have anticipated the myriad consequences of the loss of these fish populations, the economic impacts of unregulated fishing and dam construction were already quite apparent. Historically Maine’s rivers received significant runs of Atlantic salmon (Salmo salar), blueback herring (Alosa aestivalis), American Shad (Alosa sapidissima), rainbow smelt (Osmerus mordax), Atlantic sturgeon (Acipenser oxyrhynchus oxyrinchus), shortnose sturgeon (Acipenser brevirostrum), tomcod (Microgadus tomcod), sea lamprey (Petromyzon marinus), striped bass (Morone saxitilis) and alewives (Alosa pseudoharengus) (Saunders, Hachey and Fay 2006). While these species have seen variable commercial and recreational harvest, due to the combined effects of fishing pressure, habitat loss and pollution all of these populations exist today at significantly to extremely depleted levels (Moring 2005).

The Atlantic salmon, due to many factors including its size, beauty, commercial importance and extreme depletion has often served as the poster child for the degradation of New England’s diadromous fish communities. An incredible amount of money and effort has gone toward the restoration of the Atlantic salmon, but as of now the results can be described as variable at best (Grout 2006). When compared to the perceived majesty and almost mythical status of the Atlantic salmon the lowly alewife may seem of relatively little importance. However, this small, unassuming fish may represent a keystone species for Maine’s fishing economy.

Unfortunately, as with the other species mentioned above, all is not well with alewives. While this species has survived at a level capable of supporting a modest commercial fishery the population has seen great fluctuation throughout nearly four centuries of exploitation with several notable periods of decline (Hass-Castro 2006). Today the future of the fishery seems once again to be in jeopardy. A March 2008 article in the Portland Press Herald describes a fishery in crisis. With other East Coast states closing their alewife fisheries and the federal government pushing for a ban, Maine’s alewife fishermen are struggling to show that the fishery is well maintained and capable of withstanding moderate fishing pressure (Bell 2008). This however is only the most recent development in the complex socioecological history of alewives in Maine. This diminutive fish has throughout the centuries played an important role in the building of a nation and in the future may hold the key to the preservation or recovery of fisheries with enormous cultural, recreational and commercial importance such as Atlantic salmon, Atlantic cod (Gadus morhua), American lobster (Homarus americanus) and striped bass (Morone saxitilis).

This article will establish the past and present cultural and ecological importance of the alewife. Historical documents, scientific literature, local newspapers and accounts from interviews conducted by the author will be used to show that alewives are a key species in both the physical and cultural ecology of Maine.  Throughout the article it will be argued that holistic management of complex socioecological environments with a focus on often neglected species such as the alewife will be necessary for the restoration of Maine’s diadromous and possibly inshore, marine fish stocks.

The majority of the paper will be generally applicable to the Gulf of Maine as a whole. However, with the goals of grounding the scientific and historic data presented here and suggesting more specific ways in which restoration might occur, the freshwater tidal ecosystem of Merrymeeting Bay is given specific attention. Without any restriction due to dams the bay represents a significant area of potential spawning habitat for anadromous fishes (Friedman 2000). The environmental history of the bay has also been extensively documented and a great deal of research is ongoing (Lichter et al. 2006). Thus, Merrymeeting bay represents an ideal case study to supplement the research summarized in this paper.

Profile of an unlikely hero: The alewife (Alosa pseudoharengus)

Each spring as early as February they begin arriving, at first alone as scouts and then in small groups. As the spring sun rises higher and the water warms they swarm up the Nemasket by the tens of thousands. By late April and early May the fish flowing up stream seem to overwhelm the water flowing down.

- Timothy Watts 2003


Figure 1: The adult alewife (Alosa pseudoharengus) (Taken from Bigelow and Schroeder 1953)

The account given above describes the most visible and most impressive stage in the life history of the anadromous alewife. Every spring as water temperatures warm these small, silvery fish surge upstream toward their natal lakes, streams and ponds to restart their complex life cycle. The alewife is a member of the clupeids, commonly known as the herrings (Saunders, Hachey and Clem 2006). Their species range encompasses nearly all of the east coast of North America, historically extending from the St. Johns River in Florida to the rivers of Newfoundland and currently extending as far south as North Carolina (Maine DMR 2006). The fish are small, reaching a maximum length of only 15 inches in older specimens.  However, because they first migrate upstream to spawn after only three or four yeas at sea the majority of individuals observed are considerably smaller (NOAA). Alewives are for most purposes grouped with a similar species, the blueback herring (Alosa aestivalis). While it is possible to make a distinction between the two species, their spawning runs largely overlap and they play extremely similar ecological roles (Maine DMR). Under the National Marine Fisheries Service they are managed as a single species; river herring (NOAA). Similarly, few if any of the historical documents referencing alewives make a distinction between alewives and blueback herring. Thus, it is clear that the species are very similar and often grouped together as a single species. Therefore, in the remainder of this paper the term alewives will refer to both true alewives and blueback herring.

This upstream migration of alewives begins when water temperatures fall within a suitable range, generally 41-50°F. Thus, the timing of this migration varies throughout the species range with earlier migrations occurring in more southerly rivers (NOAA). In Maine this migration begins as early as April and peaks in May and June (Flagg 2007). The adults will spend as long as several months in the ponds and lakes in which they well eventually spawn as they wait for water temperatures to reach the low 60s at which time females will release up to 300,000 eggs (Bigelow and Schroeder 1953). During this time the adults feed primarily on zooplankton and terrestrial insects (Willis 2006). The alewife is capable of spawning in a wide variety of habitats and substrates, but prefers shallow, protected waters in lake and ponds or the slowest moving reaches of rivers and streams (Schalit, Winter and Wippelhauser 2003). They have been observed spawning on most aquatic substrates including gravel, sand, submerged aquatic vegetation and detritus (NOAA).  After spawning some of the adults die while many begin a downstream migration back to the sea and return in subsequent springs to spawn again (Schalit, Winter and Wippelhauser 2003).

Fertilized eggs will hatch in only a matter of days introducing hundreds of thousands of tiny juveniles in to the freshwater ecosystem (Flagg 2007). The juveniles will spend between a few weeks and a few months feeding on zooplankton and growing to a length of several inches in the ponds, lakes and streams in which they hatched (Willis 2007). From mid summer in to the fall juvenile alewives migrate downstream to the ocean where they will spend three to five years growing to maturity (Schalit, Winter and Wippelhauser 2003). As with most anadromous fish species there is a deficiency of knowledge about the ocean phase of the alewife life cycle. It is believed that alewives migrate while at sea in response to changing water temperature while feeding on zooplankton and small fishes (NOAA). Throughout their lifespan alewives engage in an incredible number of interactions with their environment, other freshwater and marine species, and humans.

A fish for any need: Historical and current importance of the alewife

The ancient standers remember that hundreds of Indians would come from Mount Hope and other places every year in April, with great dancings and shoutings to catch fish at Cohannit and set up theyr tents about that place until the season for catching alewives was past and would load their backs with burdens of fish & load ye canoes to carry home for their supply for the rest of the year and a great part of the support of ye natives was from the alewives.

-17th Century account of alewives in Taunton, Massachusetts (Watts 2003)

Due to the impacts of war and epidemics on the pre-Columbian populations of the New World it is difficult to estimate just how many people were living in Maine prior to the arrival of Europeans. Rough estimates suggest that tens of thousands of Native Americans inhabited modern-day Maine for around 9000 of years prior to contact (Whitney 1994). Archaeological research along the St. Croix River has identified alewife remains in Native American middens dating back 4000 years and the presence of alewives in the same river over 8000 years ago (Spiess 2007). While the hunter gatherer tribes of Northern Maine likely only utilized the alewife only as a food, more southern agricultural tribes likely utilized this abundant fish as a fertilizer for corn and other crops (Vogel 1987). Because of the extensive alteration of New England Rivers many archaeological sites that may provide more information on the resource use of past cultures has been lost to erosion and flooding. However, faunal remains from a pre-contact site in Northern Maine were composed of 85% fish bone, the majority of which were most likely alewife bones (Spiess and Cranmer 2005). Given the broad geographical range of alewives it is likely that they have been abundant in Maine for many thousands of years. It is difficult to imagine given the available archaeological evidence and historical accounts such as that given above that alewives were not extensively used by Native Americans for many centuries prior to contact. Ironically, one of Maine’s last abundant runs of alewives returns to the Damariscotta River, a Native American name meaning “place of abundance of alewives” (DLWA).

Alewives were also an important resource for the first Europeans in New England (Flagg 2007). After a harsh winter the spring run of alewives must have provided an abundance of food in a time of scarcity for Native Americans and colonists alike. The numerous laws, petitions and acts put forth to protect alewives and other anadromous fishes by many towns during America’s infancy are testament to the importance of the species. Towns from throughout Maine relied heavily on the anadromous fish runs that seasonally filled their rivers. And from the earliest times they recognized the detrimental impacts of blocking the passage of these migrating fish (Watts 2003).

Since the first of New England’s streams were blocked and diverted by human made obstructions there has been conflict between competing interests (Steinberg 1991). On the one hand a great deal of wealth and sustenance is to be had from the migrating fish, but on the other hand the power of flowing water is a cheap, abundant form of energy. In a meeting of the senate in 1785 Samuel Adams spoke on behalf of the fisheries of the Presumpscot River saying :

Whereas it appears to this Court that the people who live in the neighborhood of Presumpscot River in the County of Cumberland have heretofore, and still may, derive extensive benefits from the fishery on the said river and streams which fall in to the same, unless prevented by the mill-dams which have or may be erected across the said river and streams, the increase or even continuance of which unregulated, for any considerable length of time, must inevitably destroy the annual course of fish up said river (Adams 1785).

As America began to grow in the early 19th century small mills and dams were replaced with taller, permanent obstructions and enormous mills and factories the potential impact on anadromous fish increased (Steinberg 1991). This conflict which began over three centuries ago continues today on a much grander scale and with much higher stakes (Watts 2003).

Despite the detrimental impacts of mills and dams, successful and important commercial alewife fisheries developed on many rivers and streams throughout Maine (Taylor 1951). In the early years of the fishery alewives were primarily used for food. Prior to 1785 various types of nets were used to harvest the abundant alewives, but as demand increased weirs and traps became the more popular method (Hamlin and Ordway 1975). The fish were initially caught primarily for local consumption, but as markets became established tons of alewives were salted and smoked near the rivers in which they were caught then packed aboard ships from Southern New England for distribution throughout the world (Ibid.) By the mid 1800s alewives were also recognized as an excellent bait for catching groundfish which increased demand for the fish in New England (McFarland 1911). Until very recently alewife fishing was conducted exclusively once the fish had entered streams and rivers (NOAA). Thus, control of the fishery has always been the responsibility of the towns by which the fish pass. Fishing rights were sold, auctioned or leased by the town to individuals who could for the most part take as many fish as they desired (Watts 2003).

With increasing fishing effort the catch increased greatly throughout the 19th and in to the 20th century peaking in the 1960s before declining rapidly. With the advent of refrigeration and the changing tastes associated with this technology the market for alewives as a food fish declined, however, they became important in the fish meal industry and continued to be an important source of bait for other fisheries (FaOC). During the 1960s as foreign fleets increasingly moved in to the Gulf of Maine alewives were briefly the target of an ocean fishery, but with the establishment of the 200 mile exclusive economic zone this fishery was quickly halted (Hass-Castro 2006). By 2008 most of the Atlantic States have closed their alewife fisheries. Maine became the leading harvester of alewives with the close of the more productive North Carolina fishery in 2007.  The majority of Maine’s harvest is now used as bait for the booming lobster fishery; the springtime arrival being well timed to replenish depleted bait supplies (Bell 2008).

It is clear that the alewife has played numerous roles throughout a large portion of the history of human occupation in Maine. Whether as food in 4000 B.C. or as lobster bait in 2008 the spring arrival of the alewife has been a welcome relief to strained resources. However, it is also clear that humans have impacted the alewife and its environment, especially in the two centuries since industrial development and large scale fisheries spread along the coast and rivers of Maine. Before considering the ecological interactions in which the alewife participates or participated in it is necessary to understand the relative change in abundance of the alewife as well as the causes of this change.

Excess and neglect: The decline of the alewife

The Alewife is like a herrin, but has a bigger bellie therefore called Alewife, they come in the end of April into fresh Rivers and Ponds; there hath been takin in two hours by two men without any Weyre at all, saveing a few stones to stop the passage of the river, above ten thousand

– 1674 account of alewives in Maine (Josellyn 1988)

One would be hard pressed to find alewives in such abundance as described above in any river or stream in Maine today. Many streams have been empty for so long that the memory of the fish is all but lost in the towns that once no doubt depended on them (Day 2006). The logical question is how did this change come about? An extensive body of literature exists on the changes in the ecology of New England and its water ways since the arrival of Europeans and it is not within the scope of this paper to describe these changes in great detail (Steinberg 1991; Whitney 1994; Buchsbaum 2005). However, since at least as early as 1867 it was understood that habitat loss due to impassible dams, overfishing and pollution were they key causes of depleted anadromous fish stocks (Atkins and Foster 1867). Despite all the extensive research and long time knowledge of the reasons behind this degradation the situation has improved little today.

The physical obstruction caused by impassable dams represents the oldest and most obvious cause of the decline in alewife stocks. The numerous laws and petitions requiring dams to be removed or provide fish passage dating back over three hundred years are testament to the early understanding of their impacts (Watts 2003). The extensive deforestation that occurred in Maine during the same period degraded the quality of the habitat that was still accessible by clogging it with soil from the eroding banks of the rivers (Cumbler 2001). The potential impacts of overfishing were also recognized early on, with a centuries old tradition in most Maine towns requiring free passage of alewives on Sundays during their upstream migration (Kircheis and Stanley 1981). As Maine began to industrialize in the 19th century the conflict of interests between fisheries and mills intensified as millions of gallons of untreated waste were dumped in to Maine’s rivers (Moring 2005). The resulting three pronged attack on anadromous fish has caused catastrophic declines in the range and abundance of many species (Lichter et al. 2006).

Because of the long time span of ecological disturbance and spotty statistics on river fisheries it is difficult to create a high resolution image of the history of alewife stocks (Saunders, Hachey and Fay 2006). What we do know of historic abundance comes mostly from anecdotes and catch records of unknown accuracy, in varying metrics and from disparate locals. While the sheer abundance of resources encountered by the first Europeans to arrive in America no doubt lent itself to hyperbole it is certain from early accounts that alewives were plentiful in nearly all of Maine’s rivers and streams (Mullen, Fay and Moring 1986). Reports from state and federal government agencies provide some insight in to the number of alewives being caught statewide by the end of the 19th century. A federal report estimates that in 1880 10,000,000 alewives or approximately 5 million pounds were taken in New England and that by the turn of the century this had risen to 12,000,000 fish or around 6 million pounds (McFarland 1911).  While Maine’s contribution to this total is not specified the 1898 Report of the Commissioner of Sea and Shore Fisheries to the State of Maine estimates that nearly five million alewives were taken in Maine alone in that year (Nickerson 1898). By 1956 this total had nearly doubled with 4,587,900 pounds or nearly 10,000,000 fish being taken (Maine DMR 2006).

Given extreme habitat loss and pollution the increasing alewife catches throughout the 19th and 20th centuries almost certainly represent increased fishing effort rather than an increase in fish abundance. Despite increased catches of alewives Bigelow and Schroeder (1953) observed that “the alewife population in the Gulf [of Maine] is much smaller, today, that it was half a century ago” (106). Fewer and fewer fish were being allowed to reach their ever diminishing spawning grounds. While local depletion of alewife and other diadromous fishes is evidenced by many historical accounts (Watts 2003), fisheries records show that the overall production of the fishery state-wide increased through the 1956. The following year the catch fell slightly and fell again in 1958. In 1959 the landings crashed to only a third of peak levels (Maine DMR 2006).

Figure 2: Alewife landings for Maine and the United States, 1950-2006 (Adapted from Maine DMR and ASMFC)


Catches rebounded somewhat in the 1970s although the reasons behind this increase are poorly documented. The improved river conditions associated with the 1972 passage of the Clean Water Act have lead to substantial ecosystem recovery in some Maine rivers (Licter et. al 2006). Immediate reductions in pollution may have lead to a short term recovery in alewife populations, but this is only one of many possibilities.  Despite any improvements in water quality that may have benefited alewives by the 1980s both Maine’s and the nation’s catches had dropped to historic lows (Maine DMR 2006, NMFS). Maine saw a significant rebound in the alewife fishery in the 1990s due in part to statewide changes in weekly fishing closures. In 1988 a mandatory 48 hour period of fish escapement became the standard and in 1995 this was extended to 72 hours (Maine DMR 2006). During this same period national catches remained at historic lows. While habitat loss, pollution and local overfishing certainly still contribute to the deteriorated state of the alewife fishery several new causes have been hypothesized. These include increased predation by recovered striped bass populations and extensive bycatch by offshore herring fleets (NMFS, Maine DMR 2006). Fisheries independent data suggests that alewife abundance is down throughout the species range and this has led the National Marine Fisheries Service to list alewives as a species of concern (NMFS). Accompanying the species of concern label is a mandate that any state that cannot prove the sustainability of its fishery may be subject to a federally imposed moratorium (Bell 2008).

For thousands of years alewives have engaged in important interactions with humans. Today it is uncertain as to whether this tradition can continue. A federally imposed moratorium would end the small scale fishery that supplies bait to one of the most successful fisheries in the country; the Maine lobster fishery. However, if stocks continue to decline a moratorium may be the only hope for the recovery of alewife populations. While it is important to consider the ways in which alewives have interacted with humans throughout history this is inherently a single-species discussion. Increasingly it is being recognized that in order to effectively manage a fishery the ecological interactions of the target species must be addressed (Francis et. al 2007). When considered in the context of the Gulf of Maine Ecosystem, the ways in which alewives have interacted with humans throughout time prove to be far more numerous than only the direct interactions described above.

A Brief Digression on the Definition of Natural

The remainder of this paper will be dedicated to exploring a select few of the ecological interactions of alewives and based on these interactions argue for increased protection of the species. Restoration of alewife and other diadromous fish populations will require both the environment and human practices to be altered. Reducing pollution, increasing spawning habitat, carefully monitoring river fisheries and placing greater regulations on the bycatch of at sea vessels will most likely all be necessary for success. These changes are ostensibly to restore Maine’s rivers to their natural state. However, after thousands of years of human occupation and two centuries of intense industrialization defining the ‘natural state’ of anything in New England seems impossible. The ecosystems of Maine’s rivers have been altered in ways that are unknown and thus it is difficult to define just what the goal of restoration is. The impossibility of restoring an ecosystem to some past state is widely accepted in the field of restoration ecology (Palmer, Falk and Zedler 2006). In defining the goals of restoration it should therefore be recognized that Maine’s rivers and the Gulf of Maine are inherently socioecological environments. It is impossible to separate the human impacts from whatever it is we think of as ‘natural’. Importance to humans should therefore factor in to the development of restoration goals. A healthy, resilient ecosystem is clearly the ultimate goal, but implicit in this is a desire for productive fisheries (Pederson and Robinson 2005).

Maine’s river fisheries in some ways represent a blank slate. Most of them have been so severely degraded that even the memories of the fish that once passed upstream have been lost. Restoring diadromous fish runs to even half their historic levels would provide extreme economic and cultural benefits to the state of Maine. This fact has been widely recognized, but until now most restoration efforts have focused on Atlantic salmon (Grout 2006). Saunders, Hachey and Fay (2006) have suggested that restoration of Atlantic salmon cannot happen without restoration of the ecosystem in which they were once abundant; an ecosystem that included a suite of diadromous fish that are depleted today. Thus, in this way restoration of the alewife becomes tied to the restoration of a potentially more culturally and economically valuable fish species. Each of the socioecological interactions explored below are similar to the alewife’s interaction with salmon in that the species discussed are of great cultural or economic importance. While restoring alewife populations should be a worthy cause in itself the unfortunate truth is that most people don’t know what an alewife is anymore and in order for restoration efforts to be successful they often require public support. By selecting only a few of the species with which alewives interact I am not suggesting that these are the most important in a purely ecological sense. However, it is my hope that by highlighting the ways in which alewives interact with socially and economically important species a wider audience might be persuaded of the importance of protecting these fish.

The Alewife as a Keystone Species

Over the past couple of decades, ecosystem considerations have been overshadowed by the fishing industry’s perspective and needs. Stock assessment models, the mainstay of commercial fisheries management, are based on the population level of biological organization – individual species of commercially important fish and shellfish – and are not based on species interactions and ecosystem dynamics.

– Judith  Pederson and William Robinson 2005

One goal of this section is to summarize the available scientific literature relating to interactions between alewives and species of great cultural and economic importance. However, in doing so it will become clear that far more is uncertain than is known about these interactions. Historical documents and interviews conducted by the author are therefore used to supplement scientific literature and suggest areas that require further study. Ultimately this section is intended to raise more questions than it answers and to illustrate the possible benefits of restoring anadromous fish, including alewives to the Merrymeeting Bay ecosystem.

Atlantic Cod

In the early spring, the alewives formerly made their appearance on the coast, crowding along our shores and ascending the rivers in order to deposit their spawn, being followed later in the season by the shad and salmon. Returning when their eggs were laid, these fish spent the summer along the coast; and in the course of a few months were joined by their young, which formed immense schools in every direction, extending outward, in some instances, for many miles. It was in pursuit of these and other summer fish that cod and other species referred to [Other Gadids] came in to the shores; but with the decrease of the former in number the attraction became less and less, and the deep sea fishes have now, we may say, almost disappeared along the coast.

-Spencer F. Baird, U.S Commissioner of Fish and Fisheries 1872

Gadus morhua, the Atlantic cod has been perhaps the single most important fish species to humanity since people first looked to the sea for sustenance; for centuries the vast quantities of cod taken from the North Atlantic seemed inexhaustible (Kurlansky 1997). This large, demersal, omnivorous fish was historically abundant throughout the North Atlantic with fisheries of incredible scale occurring on both sides of the ocean. The coastal waters and offshore banks of the Gulf of Maine provided an ideal environment for cod and other gadids. In 1929 Walter Rich, an agent of the United States Bureau of Fisheries reported that “it is probable that no other fishing area equal in this in size or in productivity exists anywhere else in the world, and the figures of the total catch taken from it must show an enormous poundage and most imposing sum representing the value of the fishery (Rich 1929: 52). He goes on to describe a multitude of what he calls ‘fishing spots’ within only a few miles of Maine’s coast at which cod and other groundfish were available in incredible abundance. Today the decimated groundfish populations of the Maine coast and beyond serve mostly as a reminder of what has been lost rather than the economic lifeblood of the coast.

Figure 3: Atlantic cod landings for the State of Maine. (Taken from Maine DMR) <http://mainegov-images.informe.org/dmr/commercialfishing/documents/cod.pdf>

While the offshore cod stocks of the Grand Banks, Georges Bank and similar fishing grounds have received a great deal of publicity due to their spectacular collapse (Kurlansky 1997, Harris 1998, Buchsbaum, Pederson and Robinson 2005, Brander 2007), the inshore populations of cod described above have been largely forgotten. Bigelow and Schroeder (1953), whose research was primarily conducted during the 1920s, took note of the abundant inshore cod saying

We fancy there is no patch of hard bottom, rock, gravel or sand with broken shells, from Cape Sable in the east to Cape Cod on the west, but supports more or less cod at one time or another. Cod are even caught on soft mud bottoms, though they are not common there. And while the cod are essentially a fish of the open sea, they appear regularly in various river mouths in Maine and Massachusetts during the late autumn and winter. One is taken in brackish water occasionally (189).

As otter trawl technology was developed around the beginning of the 20th century cod became vulnerable to capture during their spawning season (Kurlansky 1997). The potential for wiping out isolated spawning populations increased greatly as this technology, which used large nets dragged through schools of congregated, often spawning of fish, proliferated in New England (Murawski 2005).

Today, cod in the Gulf of Maine are managed as one stock, a management tactic that ignores the possible extirpation of unique spawning populations from nearshore environments. Edward Ames, a scientist and former groundfisherman had recognized for decades the more complex population structure of cod in the Gulf of Maine. His interest in studying the former distribution, spawning habits and migration patterns of cod in the Gulf of Maine eventually earned him a MacArthur fellowship (Bhattacharjee 2005). The findings of his first published study, which involved interviews with retired fishermen and Geographic Information System (GIS) analysis offer the highest resolution of historical cod stocks in the Gulf of Maine that are available today (Ames 2004). Ames identified discrete spawning populations all along Maine’s coast that existed during the 1920s. By the 1940s the coastal fishery had for the most part collapsed and today over half of the coastal spawning grounds are abandoned. While the feasibility of repopulating abandoned spawning areas is unclear, Ames argues that with proper management a productive coastal cod fishery can once again exist in Maine.

Ames reiterates what Spencer Baird recognized over 130 years ago; that cod migrate in to coastal waters in conjunction with the movements of forage fish including alewives (Baird 1872). Thus, Ames argues, the successful restoration of a coastal cod fishery will require the concurrent restoration of anadromous forage species. Accordingly, he plans on dedicating funds from his MacArthur Fellowship to further documenting the connection between cod and anadromous species (Bhattacharjee 2005). At present there is little hard data supporting the connection between cod and alewives. However, statements such as those by Baird (1872) suggest that people recognized the link at an early date. During the early half of the 1900s, when both alewives and cod were abundant along the Maine coast Bigelow and Schroeder (1953) documented predation on the former by the latter. Recently, a growing number of researchers, activists and policy makers are recognizing the important link between anadromous fish and marine species in the Gulf of Maine (Goode 2006). Furthermore, the recent push for ecosystem based fisheries management (EBFM) has recognized the importance of managing both prey and predator species. One of the “commandments” of EBFM proposed by Francis and his colleagues (2007) is to “identify and maintain critical food-web links” (224). Forage fish are often integral parts of these critical links. Thus, it would seem that the restoration of alewife populations will be an important element to the restoration of cod stocks in the coastal waters of Maine.

Striped Bass

The failure of the North Atlantic cod stocks is now considered by many a textbook example of the catastrophic results of ineffective fisheries management (Harris 1999). In stark contrast, a fish that once shared the coastal waters of Maine with the now absent cod is often considered one of the greatest successes of fisheries management (Walter et al. 2003). The Atlantic striped bass (Morone saxatilis) has since colonial times supported important commercial and recreational fisheries (Hartman and Margraf 2003). As with the other anadromous fish native to the Northeast United States striped bass populations were severely impacted by human actions. Overexploitation of first old, but then younger and younger fish, combined with habitat degradation led to a catastrophic collapse of the fishery during the 1970s. Restrictions put in place by the Atlantic States Marine Fisheries Commission in 1981 established strict size limits and some states imposed moratoria on the taking of striped bass (Grout 2006). Maine’s commercial striped bass fishery ended in 1984 when the sale of the fish was outlawed. However, the fishery that remained at the time was supported entirely by migratory stocks from other states; native striped bass populations having been extirpated from Maine rivers by the 1950s (anonymous 1987).

Within several years the management actions taken by the ASMFC had produced results. Striped bass populations were increasing, and today are ten times as large as during the late 1970s (Grout 2006). In Maine today no commercial fishery exists for striped bass. However, recreational anglers take large quantities of the fish as they forage in the coastal waters of Maine during the summer months.

 

Figure 4: Commercial and recreational landings of Striped bass for the Atlantic Coast, 1945-2005. (Taken from AMFSC)

 

 

 

 

 

Since the 1995 declaration of the stock as recovered recreational landings in Maine have increased from only 46,000 pounds to over 385,000 pounds in 2006 (ASMFC 2008). The vast majority of the fish taken in Maine are not native to the state. The large spawning populations of the Hudson River and Chesapeake produce the bulk of the coastal migratory population that moves north in the New England waters as waters warm in the spring (Crecco 2005). The native populations of Maine’s rivers that were lost over half a century have been responding to restoration efforts and are increasingly contributing to the striped bass population in Maine’s waters.

The construction of dams at Brunswick-Topsham on the Androscoggin and at Augusta on the Kennebec greatly reduced the native population of striped bass in Maine. Because striped bass will not enter fish ladders dams entirely exclude the fish from upstream habitats (Bigelow and Schroeder 1953). Despite this setback native striped bass continued to spawn in the freshwater habitat provided by Merrymeeting Bay up until the 1930s when it is supposed that industrial pollution drove the stock to extinction (Anon. 1987). Water quality has improved dramatically in the bay as a result of enforcement measures associated with the Clean Water Act (CWA) of 1972 (Lichter et al. ). In 1982, responding to the improved conditions, a restocking effort was undertaken for striped bass in Merrymeeting Bay (Anon. 1987). Since 1987 there has been evidence of successful reproduction in Merrymeeting Bay and the Kennebec River, and more recently in the Sheepscot River (Moring 2005). The successful recovery of spawning populations in Maine is vital when the status of striped bass is considered for the entire Atlantic coast. The Chesapeake Bay stock, which is the largest in the world, seems to have exceeded the carrying capacity of the bay in recent years. Poor fish condition and disease are now widespread in Chesapeake Bay striped bass (Uphoff 2003). Thus, it would seem that ensuring the continued presence of striped bass in Maine’s waters might increasingly rely on native spawning populations.

As made clear by the case of cod above, it is unwise to assume that a depleted population of fish will recover in the absence of formerly abundant prey. Striped bass are large, pelagic predators that have the potential to greatly impact prey communities (Hartman and Margraf 2003). Walter and his colleagues (2003) in a study of striped bass diet found that “The overall dominance of clupeid prey in the diet was the strongest trend and, in each region, size class and over all seasons. In particular, menhaden and anadromous river herrings were found in each region and contributed most to the overall diet biomass” (358). When present, striped bass prey voraciously on clupeid species including alewives. A study conducted in the Hudson River found that as the striped bass population recovered predation on alosids including alewives became an important factor in juvenile mortality for the prey species (Hartman 2003). Hartman (2003) explains that “Even in the more conservative (10% diet) Hudson River scenario, age-1 and age-2 striped bass alone were able to eat 2-10 times the estimated October 1990 biomass of age-0 alosids in the river” (286).

Figure 5: Estimated age-1 and age-2 striped bass consumption of age-0 alosids in the Hudson River, 1985-1994 (Taken from Hartman 2003).

Many other studies have shown the importance of alewives and similar fish species in the diets of striped bass. Uphoff (2003) documented the importance of menhaden as food for striped bass in the Chesapeake Bay ecosystem and concluded that competition between fisheries and striped bass for the resource is limiting the population of the predators. On the North Shore of Massachusetts, a habitat very similar to that of the Maine coast, two studies found clupeids, including alewives to compose an important part of the diet of striped bass (Nelson, Chase and Stockwell 2003, 2006). Studies of striped bass diet have not been conducted in Maine, and this represents an area that will certainly warrants more study. There is evidence that even small striped bass in Maine waters are capable of consuming juvenile Atlantic salmon during their downstream migration (Beland et al. 2001). Because of the overlap in the timing of salmon and alewife runs it is probable that the similarly sized alewife would also be subject to predation by striped bass in Maine (Saunders, Hachey and Fay 2006).

The last time that striped bass were this abundant the other anadromous species that provided forage were also much more abundant. Saunders, Hachey and Fay (2006) hypothesize that the recovery of Maine’s diadromous fish populations will require restoration efforts for all species because they have coevolved making each species dependent on others. Migratory striped bass have managed to recover without the concurrent recovery of Maine’s diadromous fishes. Thus, one must wonder just what it is that the striped bass are eating in the absence of their preferred prey. Atlantic salmon smolts and American lobster have been shown to be two likely options (Beland et al. 2001; Nelson, Chase and Stockwell 2006). The implications of this shift in prey will be discussed below.

Atlantic Salmon

Atlantic salmon are symbolic of a time when the biological endowment of the eastern United States was richer and more diverse than today. These impressive fish were once abundant in the rivers of Maine and their range extended south and west as far as the Connecticut River and perhaps even to the Hudson River. Today the distribution of Atlantic salmon in the eastern United States is restricted to a few rivers of Maine where total annual runs are numbered in hundreds of fish rather than the tens or perhaps hundreds of thousands of the past.

-Michael Clegg, Chair, Committee on Atlantic salmon in Maine 2003

The decline of Atlantic salmon in Maine and the North Atlantic  at large has been well documented (Clegg 2003). Maine’s rivers were once the hosts of some of the largest runs of Atlantic salmon in the world, but today returns are counted in the hundreds (Day 2006). The early history of the decline is very similar to that of the alewife given above. The same three impacts of overfishing, habitat degradation and pollution have largely been attributed with the extirpation of salmon from most of Maine’s rivers and streams (Buchsbaum 2005). However, more recently the stories of alewives and salmon have diverged. As Clegg (2003) notes above, Atlantic salmon are iconic of a New England that no longer exists, a fact that has made them the focus of intense restoration efforts far beyond any ever carried out on the behalf of alewives. And despite the great deal of money and effort that has gone toward saving the Atlantic salmon their numbers have continued to steadily decline, eventually leading to the classification as an endangered species in Maine in 2000 despite a halt to commercial fishing in 1948(Grout 2006).

Understanding the possible causes of the poor recovery Atlantic salmon may help shed light on the causes of the recent decline in alewife abundance throughout the species range. The large range of the decline suggests a change in at-sea survival, and a study by Cairns (2001) which evaluated the threats to Atlantic salmon found that the majority of the top rated threats were associated with oceanic and estuarine conditions. The marine phases of most anadromous fish are poorly understood and it is beyond the scope of this paper to suggest ways in which marine survival of alewives or Atlantic salmon might be improved (Goode 2006). While the two fish are linked by the fact that the influences affecting marine survival may be similar, the species are also linked in a more concrete ecological relationship that will have important implications for the recovery of the prized Atlantic salmon.

The list of things that have changed since the last time Atlantic salmon were abundant in Maine is extensive. While habitat degradation and loss and pollution of native spawning grounds have often been seen as the primary bars to salmon in Maine rivers, recently a group of researchers have offered an alternative, or perhaps supplementary perspective. It has been observed that even in the presence of well maintained fishways, improved water quality and reopened portions of rivers salmon have not readily returned to former habitats (Moring 2005). Saunders, Hachey and Fay (2006) have proposed that other formerly abundant anadromous fish, primarily alosids such as alwives, engaged in vital ecological interactions with Atlantic salmon in Maine’s rivers. Based on the shear numbers that can be estimated from historical accounts (likely in the hundreds of millions) and the temporal overlap of the presence of anadromous fish in Maine’s rivers it seems intuitive that the other fish acted as an important part of the salmon’s environment (Taylor 1951).

Figure 6: Life histories of several of Maine’s diadromous fishes (Taken from Saunders, Hachey and Fay, 2006)

Saunders, Hachey and Fay (2006) identify three ways in which alewives likely interacted with Atlantic salmon. The most obvious benefit that salmon derived from other fish was an abundant prey source. Both salmon smolts and kelts (adults migrating downstream after spawning) have been shown to prey extensively on alosids where both are still abundant (ibid.). Depleted alewife stocks therefore mean that salmon lack an important food source during key life history stages. At the same time it is probable that the increased abundance of adult striped bass is leading to competition with atlantic salmon for alewives and other prey (Grout 2006). This provides yet another example of how ecosystems can be unintentionally impacted by single-species fisheries management.

The second interaction that Saunders, Hachey and Fay (2006) propose is far less direct. The influx of nutrients that abundant anadromous fish introduce in to freshwater ecosystems has important impacts on both aquatic and terrestrial environments (Wilson and Halupka 1995). A study of streams with alewife runs in Rhode Island found that alewives provided an influx of nutrients in to the aquatic environment with their decomposing bodies and excretion that was far in excess of the nutrients lost by juvenile emigration (Durbin, Nixon and Oviatt 1979). In a bottom up fashion these nutrients are thought to fuel the freshwater environment in which juvenile salmon and other species of anadromous mature (Saunders, Hachey and Fay 2006).

The third mechanism by which alewives are thought to be beneficial to the survival of Atlantic salmon is through an ecological interaction known as prey buffering. This interaction is not well documented for anadromous species, but makes a great deal of sense when considered alongside the migration times of the various anadromous species. What Saunders, Hachey and Fay (2006) propose is that the abundance of migrating alewives and other alosids during the downstream migration of Atlantic salmon provided an abundant alternative prey source for species such as striped bass, cod, birds and marine mammals. This theory gains a great deal of support from a study conducted on the Tana River in Norway, which today has the world’s largest Atlantic salmon run (Svenning et al. 2005). This study looked to document the level of predation on juvenile salmon by marine fish species and birds in the Tana River estuary. The researches had anticipated to find a significant level of predation by cod and other groundfish species which have been shown to consume Atlantic salmon in other estuaries in Norway. However, after sampling the stomach contents of large numbers of the species in question no evidence was found of predation on salmon. What Svenning and his colleagues (2005) did observe in nearly every stomach sampled was an abundance of lesser sandeels. The researchers concluded that the lesser sandeel acts as a prey buffer by providing a more abundant and nutritious food source for potential predators and that this likely contributes to the Tana’s status as one of the most important salmon rivers in the world.

This research has several important implications for the situation in Maine. First, it provides experimental evidence of a prey buffering effect in anadromous fishes, including the Atlantic salmon. Second, it provides evidence that in the absence of alternative prey, groundfish will consume juvenile salmon. We are once again faced with the complex reality of our marine ecosystems. Efforts at restoring coastal cod populations may be in direct conflict with Atlantic salmon restoration if alewives and other prey species are not abundant. When these two demands are combined with the increased predatory pressure exerted by a recovered striped bass population it seems unlikely that the severely depleted alewife populations present in Maine today can satisfy the food needs of all these important species. In the absence of alewives just what are these other species eating? Evidence gathered from fishermen during my research in Harpswell, Maine during the summer of 2007 may lead us in the direction of answers to this question.

American Lobster: A synthesis in the context of Maine’s most important fishery

Despite repeated warnings for nearly a century that lobster stocks are overfished and collapse is imminent, stocks throughout the western North Atlantic remained stable and in recent years surged dramatically. In fact, landings in Canada and the United States in the 1990s have exceeded record highs and most scientists agree that this increase is primarily driven by high abundance rather than simply increased fishing effort

-Robert Steneck, University of Maine 2005

Today, Maine’s successful lobster fishery stands out in stark contrast to most commercially important species. In fact, for most of the fishermen in Maine it is currently the only viable way to make a living from the sea (Acheson and Steneck 1997). It may seem at first that the closest connection between alewives and lobsters is that lobstermen fill their traps with alewives only to later empty them of lobsters. It is true that in considering direct predator-prey relationships there is no connection between the two species under natural circumstances. However, evidence suggests that under the right conditions both striped bass and cod won’t pass up the opportunity to devour a lobster; a fact that has not gone unnoticed by Maine’s lobstermen. Because both these species have been shown to prey on alewives, Maine’s lobster populations are inextricably linked to the abundance of alewives produced by Maine’s rivers (Uphoff 2003; Nelson, Bradford and Stockwell 2006).

On an early summer day in 2007 I accompanied a successful lobsterman from Harpswell, Maine on his boat as he hauled his traps for the day. As each trap came over the side of the boat he and is sternman would process the lobsters at an incredible rate. Juveniles, oversized individuals and berried females were rapidly discarded overboard and any legal sized lobsters were set aside to be dealt with later. As this process continued on I casually mentioned that I had been enjoying the spring’s striped bass fishing. While it seemed like little could interrupt the rapid pace of the work at hand the captain of the boat stopped and turned to me after this comment. “If I had my way” he said “I’d set a million gillnets and kill them all.” His strong feelings about the recent return of the striped bass shocked me. He went on to explain that striped bass consumed millions of juvenile lobsters every year. He recalled multiple occasions on which the fish would follow his boat, consuming the juveniles he was so rapidly throwing back to the sea.

Upon returning home that day I set out to find further documentation of striped bass preying on lobsters in Maine, but with little successes. In later interviews with lobstermen I inquired specifically about striped bass. Many had observed increasing numbers of juveniles caught in their traps and also suspected that the larger individuals were preying on lobsters. I had never doubted these men who spent their lives working on the sea, but because my primary interest was their observations of climate change I had not fully pursued the issue until I began research for this paper.

To my knowledge there is still no scientific documentation of striped bass preying on lobsters in Maine. However, studies from the North Shore of Massachusetts suggest that the level of predation is very high indeed (Nelson, Chase and Stockwell 2003, 2006). Nelson, Chase and Stockwell’s (2003) initial study on striped bass food habits in Massachusetts waters identified lobster to be a primary prey species. Their further research (2006) found that in the waters of Northern Massachusetts striped bass were consuming more lobster biomass than fishermen were catching. Thus, the fears of lobstermen do seem to be supported by these initial studies. Clearly, more in depth research of striped bass feeding habits within Maine’s waters should be a high priority.

Bigelow and Schroeder (1953) suggest that cod will also consume lobsters. Some have suggested that the recent abundance of lobsters is largely the result of the population being released from predation pressure with the crash of Atlantic cod stocks (Acheson and Steneck 1997). The extent to which predation pressure from cod controls lobster abundance remains unclear. However, a recovered coastal population of cod in Maine would certainly add new pressures to an ecosystem that has been without such species for many decades. Wilson, Yan and Wilson (2007) warn that “events in the rest of the ecosystem have turned lobsters into a monoculture that is potentially subject to disease and the instabilities of an eroded system” (15212). The fishermen I interviewed also expressed concern that there is little else left for them to do but fish lobster. Most saw today’s high catches as a divergence from the normal and feared that younger fishermen who were deep in debt would be ruined if the catches returned to their historical average of about one third of what seems normal today. Thus, the current socioecological situation appears unstable and destined for inevitable, rapid change.

It may still be unclear just what all this has to do with alewives, but I assure you that it will all be made clear momentarily. Consider the three fish species discussed above. Each spends some portion of its life in the waters of coastal Maine. Each is considered important both culturally and economically. Each is fundamentally competing for limited resources while in Maine’s waters. If we accept (which we must) that the productive capacity of any given area of ocean is finite then the restoration of cod, Atlantic salmon and striped bass are fundamentally in conflict. The potential that I want to make clear is that the conflict, if not in some way mitigated may take its toll on the only thing that allows the fishing tradition in Maine to continue on today; the abundance of lobsters (not to mention slowing if not preventing the restoration efforts in question). And so we return to the lowly alewife. This small fish I believe may be the key to fulfilling the competing needs of multiple restoration efforts. The simplest version of what is potentially occurring in a very complex system is depicted in the following figure:

Cod Salmon Striped bass Lobsters
Alewives Cod prey on alewives and historically followed migrating schools to coastal waters Salmon prey on alewives and juvenile salmon experience a prey buffering effect from alewives Striped bass prey extensively on alewives Lobsters may experience a prey buffering effect in the presence of alewives because stripped bass prefer to eat fish
Cod Cod prey upon juvenile salmon Striped bass and cod may compete for prey in coastal environments Cod prey on lobsters, although the extent of this predation is unknown
Salmon Striped bass prey upon juvenile salmon and the species may compete for food in estuaries Both serve as prey for cod and striped bass so salmon might offer a prey buffer to lobsters
Striped Bass Striped bass consumer large numbers of juvenile lobsters

Figure 7: Proposed interactions between several economically important species and alewives in the waters of coastal Maine.

Based on these proposed (and generally supported) interactions, the alewife acts as a keystone species which mitigates the various pressures that these important species exert on one another. Cod will likely not return to abandoned coastal grounds without the alewives that once drew them there. Even moderate recovery of the cod population, in the absence of alewives may lead to increased predation on Atlantic salmon. Atlantic salmon, for this as well as the other reasons described above may not be able to exist in large numbers without alewives. In the presence of recovered migratory and recovering native striped bass stocks lobsters seem to be experiencing increased predation. Walter and his colleagues (2003) found that where present, clupeids such as alewives comprised the majority of striped bass diets, likely representing a prey preference over crustaceans such as lobsters. Thus, alewives could potentially mitigate the impacts of both striped bass and cod predation on lobsters. Shoreside, these abundant, coexisting, economically important species could help to stabilize the socioecological balancing act that the current lobster monoculture has created, but without abundant alewives any stabilization seems unlikely.

As noted before, this section has been intended to raise more questions than it answers. The fairly complex scenario presented here is still a gross simplification of what is actually occurring. In the end what is being suggested is that each restoration effort discussed above should take in to account the potential impacts on other species. From the data I have encountered it seems that alewives are one of the key food-web links described by Francis et al. (2007). In light of this I believe that special focus should be given to the restoration of alewives in conjunction with the efforts to restore and preserve cod, Atlantic salmon, striped bass and lobster. The following section will describe the situation that exists today in one large estuary system in Maine and propose ways in which the estuary and associated coastal waters might be restored and protected in order to facilitate the co-recovery of the species described here.

Merrymeeting Bay: Past, present and future fisheries potential

Though inferior to its elder brother, the shad, both in size and quality, the alewife excels in numbers and hardiness…In our own State, it has endured against the disadvantages that man has put in its way much better than shad or salmon. There is less wildness and timidity about its character than is the case with those fish…It seems particularly to delight in shallow, boggy waters, yet it is capable of breeding in tidal waters, as it does in the Kennebec.

-Charles Atkins and Nathan Foster, 1867

Today, as the Lower Kennebec passes Fort Popham and meets the Atlantic Ocean its waters provide recreation for sport fishermen who target the migratory striped bass that, along with millions of other tourists, vacation along Maine’s coast in the warmer months. One might find a number of small boats and a handful of anglers lining the beach if the season is right. While this is the visual representation of a recovered striped bass population it is also an insult to the memory of the fisheries once provided by the Kennebec and Androscoggin rivers. Traveling seventeen miles upstream from Fort Popham the confluence of these two great rivers is reached as one passes through ‘The Chops’ and in to Merrymeeting Bay. The Kennebec, Androscoggin, Abagadasset, Cathance, Muddy and Eastern Rivers all drain in to the freshwater, tidal ecosystem that, while not technically a bay certainly appears as one due to its vast size (9,600 acres ) and tidal nature (Hayden 1998). Constricted by the narrow passage referred to as ‘The Chops’ Merrymeeting bay experiences minimal saline input making it the largest freshwater, tidal ecosystem on the Atlantic coast of the United States north of Chesapeake bay (Köster et al. 2007). This unique ecosystem, prior to experiencing the ravages of human influence, provided valuable habitat for a suite of anadromous fishes (Lichter et al. 2006). With proper restoration and management the optimist would expect that Merrymeeting Bay will one day again be capable of supporting fisheries in the Lower Kennebec.

Figure 8: Merrymeeting Bay and the Lower Kennebec River (Taken from Lichter et al. 2006)

Prior to human interference the Merrymeeting Bay watershed was visited by all species of diadromous fish described in the introduction. Among the most economically important were sturgeon, salmon, shad and alewives which visited the bay in great numbers during their migrations (Foster and Atkins 1869). Slow growing sturgeon are thought to have succumbed primarily to overfishing, but the more prolific species flourished until the construction of large dams began in 1815 with the Androscoggin being blocked at Brunswick-Topsham (Lichter et al. 2006). The construction of Edwards Dam in Augusta which was completed in 1837 effectively blocked off the upper portions of the Kennebec to anadromous fish (Taylor 1951). The consequences were immediate and devastating for Atlantic salmon which requires cool, shallow streams found only near the headwaters of large rivers. The Kennebec River salmon fishery, which is thought to have been one of the greatest in the country was destroyed and has yet to recover (Clegg 2003).

However, many other anadromous fish continued flourish in Merrymeeting despite these large obstructions (Lichter et al. 2006). The minor rivers flowing in to the bay, the lower portions of the Androscoggin and Kennebec and Merrymeeting bay itself offer acceptable spawning habitats for species such as alewives, shad and striped bass (Taylor 1951). Prior to dam construction it is estimated that 600,000 pounds of alewives were taken in and around Merrymeeting Bay annually, and from 1837 until the 1930s a sizeable fishery remained (Anon. 1987). Maine’s largest shad fishery was also maintained through spawning in the same areas up until the 1930s as was the only remaining spawning population of striped bass in Maine (Moring 2005). By the 1930s escalating industrial pollution devastated the remaining anadromous fish populations in Merrymeeting bay (Köster et al. 2007). The primary source was the Androscoggin, a river whose pollution is almost legendary due to events such as when in 1941 a period of low water caused the putrid fumes of the river to peel paint off nearby buildings (Uttormark 1984). Lichter and his colleagues (2006) give an extensive environmental history of Merrymeeting Bay. Along with overfishing and pollution they identify an altered hydrological regime due to severe sedimentation as another significant impact of human activities.

Today the ecosystem has recovered significantly from its entirely collapsed state in the mid 20th century (Lichter et al. 2006). A 1987 report on the fish of the Kennebec River argues that “Since the early 1970’s, water quality has improved dramatically and the tidal waters of the Kennebec River should support an alewife population similar to that found in the ecosystem after 1837” (Anon. 1987:14). The 1999 removal the Edwards Dam at Augusta has opened 18 miles of the Kennebec that were previously inaccessible suggesting that a population considerably larger than that suggested in the report should now be possible (NRCM 2008). A modest run of alewives currently exists in the river as well as juvenile recruitment in shad and striped bass (Lichter et al. 2006). Thus, the situation with which we are presented today offers a great number of opportunities for restoring anadromous fish to the Merrymeeting Bay ecosystem. Key areas for research and management are discussed below:

Characterization and control of the impact of introduced carp

A current challenge to the restoration of anadromous fishes in Merrymeeting Bay is the presence of the common carp (Cyprinus carpio). This species, which is thought to have been introduced to the lower Kennebec in the late 1800s, has been shown to increase the turbidity of the waters due to its benthic foraging practices (Anon. 1987). A study in Ontario found that when carp were excluded from a body of water the downstream water quality improved significantly with drastic reductions of inorganic suspended sediments (Barton, Kelton and Eedy 2000). It has been shown that the increased turbidity caused by carp leads to reduced growth of submerged aquatic vegetation which represents a key habitat for juvenile fish and many invertebrate prey species (Lougheed and Chow-Fraser 2001). The presence of carp in Merrymeeting Bay is likely responsible for reduced water clarity and limited growth of submerged aquatic vegetation. The result is that while a great deal of otherwise suitable spawning and nursery habitat exists in Merrymeeting Bay it is not necessarily as productive as it was historically. This will potentially limit the extent to which anadromous fish can repopulate the bay.

Excluding carp from Merrymeeting Bay will prove difficult because they are prolific throughout all waters in the system not blocked by natural or human obstructions (Anon. 1987). The first step in mitigating the impact of carp will be a closer study of their abundance and distribution within the system. Research conducted in the Netherlands found that small reductions of introduced carp populations did little to improve water quality. Rather, it was found that a reduction threshold 70% of carp biomass exists in the studied systems, and if reached will result in significant water quality improvement (Zambrono, Scheffer and Martínez-Ramos 2001). This suggests that a large proportion of the carp must be removed from the Lower Kennebec in order to see associated water quality improvements in Merrymeeting Bay. While this is certainly a daunting task, I would propose that the feasibility of a bounty system be explored. Carp in the Kennebec have never experienced any fishing pressure. On the Columbia and Snake Rivers in the Western United States a system is employed in which anglers receive a bounty for each northern pikeminnow they catch and kill in order to protect juvenile salmon (WDFW 2008). A similar system might be usefully employed in the Kennebec.

Increase access to upstream habitat through dam removal and fishway construction

Restoring anadromous fish throughout their range on the Kennebec and Androscoggin is the ultimate goal. This will only be accomplished if proper fish passage is guaranteed to the headwaters of these rivers. The recovery of Atlantic salmon is extremely unlikely unless adequate passage to their native spawning grounds is restored. These are almost exclusively far upriver in small, cold streams (Clegg 2003). A great deal of effort and money has gone towards this goal through the Kennebec River Anadromous Fish Restoration Program run by the Maine Deparment of Marine Resources and the Maine Atlantic Salmon Commission. Further information on the program can be obtained through the annually released progress reports (Maine DMR 2002).

The State of Maine Statewide River Fisheries Management Plan (1982) has helped to identify the objectives of anadromous fish restoration and promote cooperation between the state and privately owned dams (Maine DMR 2002). Each dam presents a unique situation and will require specific research and actions to ensure fish passage. For the purposes of this paper I will only mention one notable case of the conflict that can arise when provisions for fish passage are called for; the Fort Halifax dam in Winslow. This dam, blocks the entrance of the Sebasticook as it flows in to the Kennebec, in the past several years has caused heated debate (Hickey 2007).

After the State of Maine informed FPL Energy that fish passage must be established at the dam the company was forced to weight the benefits of continued operation of the dam. A cost benefit analysis showed that the three million dollars required for the construction of a fishway was not justified by the amount of revenue created by the dam. Accordingly, FPL Energy decided that the removal of the dam was the most economical option. The company as of now has been given permission by the Army Corps of Engineers and the State of Maine to remove the dam, but a handful of upstream residents have sued due to concerns about the altered flow of the river (Clark 2008). With the breaching of the Edwards Dam in Augusta the Fort Halifax dam presents the only barrier to fish in the Sebasticook River which had large shad and alewife runs prior to the blocking of the Kennebec in 1837 (Taylor 1951). The conflicts caused by the competing interests of fish and dams will arise once again as many of Maine’s smaller obstructions are considered for removal. I would argue that the aesthetic desires of a few should not stand in the way of the potential cultural and economic benefits that the entire state of Maine would receive from restored anadromous fish runs. And thus, strong political efforts should continue to seek the removal dams in Maine.

Identify and protect critical habitats in Merrymeeting Bay and its minor rivers

It is known that Merrymeeting Bay in general has historically provided and currently provides spawning and nursery habitat for alewives and other anadromous fish (Anon. 1987). At present, the specific areas in which alewives and other anadromous fish are utilizing are unknown. In his 1951 survey of Merrymeeting Bay and the smaller rivers that flow in to it Taylor identified a great deal of what he observed to be suitable habitat for shad spawning (10-11).  He also reports that the Cathance, Abagadasset and Eastern Rivers are known to have supported shad fisheries historically. Due to the alewives ability to spawn in conditions similar to that of shad these rivers represent likely alewife spawning habitat and should be considered for protection and restocking efforts.

Within Merrymeeting Bay itself greater efforts should be made to document the distribution of adult and juvenile alewives as well as their eggs. Identifying important habitats will facilitate several activities. The most pressing issue is protecting vital areas from disturbance. Merrymeeting Bay is in a quickly developing part of Maine and provisions should be made to avoid further damage to the aquatic environment (Hayden 2003). Second, identifying productive habitats will allow for future restoration efforts to target areas that are likely to be similar to those which currently support anadromous fish reproduction. Finally, by identifying the types of habitat used by anadromous fish in Merrymeeting Bay it may be possible to design artificial habitats within the ecosystem that promote reproduction amongst alewives and other species.

Once again, the goal here is to raise questions and identify future research needs. Adequate information on the Merrymeeting Bay ecosystem is currently lacking. More frequent monitoring of the physical and biological conditions of the bay should be made a priority. I do not believe that a lack of information should be used as an excuse to delay action. Stocking efforts and artificial habitat experiments should move forward as soon as possible, especially in light of the recent listing of alewives as a species of concern by the ASMFC. I strongly believe that successful efforts at the restoration of alewives in Merrymeeting Bay will produce beneficial results for other anadromous fish species as well as marine species along the coast. Ames (2004) identified remnant cod spawning populations in both Sheepscot Bay and Casco Bay which are both spatially associated with the Kennebec River estuary. An abundant food source in alewives from Merrymeeting Bay might be they key to replenishing this specific inshore cod stock. All the other ecological interaction proposed above are also likely to result in the Merrymeeting Bay ecosystem. And yet, this is only one of many discrete systems along Maine’s coast that require further research. Restoring alewives to the coast of Maine will not be an easy task, but I believe the possible benefits justify addressing the challenges with nothing less than complete commitment.

Conclusion: Managing ecosystems for productivity and resilience

In the preceding I have tried to tell the tale of one small fish. As I try now to conclude it is quite clear that telling such a tale would not only be difficult, but rather disconnected from reality. The interconnectedness of rivers and oceans, alewives and lobsters and, humans and the natural world cannot be denied. I believe that alewives act as a keystone species all along the coast of Maine and I have tried to present evidence supporting this claim. However, I do not mean to suggest that I offer the final word on this subject. What have been given here are many ideas, observations and questions. I intend for this review of the material to be the beginning rather than the end.

Alewives for many thousands of years brought life to the original inhabitants of Maine every spring. They have survived centuries of damaging human impacts on their bodies and their environments. Thoreau wondered as he watched these tenacious fish denied passage upstream “Perchance, after a few thousands of years, if the fishes will be patient, and pass their summers elsewhere, meanwhile, nature will have levelled the Billerica dam, and the Lowell factories, and the Grass-ground River run clear again, to be explored by new migratory shoals, even as far as the Hopkinton pond and Westborough swamp” (Thoreau 1840: 18). Nature has yet to claim back all that humans have taken. Many humans though have taken up the cause of breaking the dams and allowing anadromous fish to once against swim free in our rivers and streams. Perhaps what I have presented here can contribute in some small way to these efforts. As I see it, we don’t have thousands of years to wait. We know that the fish will not summer elsewhere, but rather they will simply fade away as just another memory of what has been lost.

There are those who might ask who cares? After all, it’s just a fish, and not a particularly impressive fish at that. To those people I offer two hypothetical futures for Maine’s coast. In the first, we accept that the alewife is just a fish. We continue on our current trajectory of indifference. Maine’s fishing community invests more and more in to the lobster monoculture until one day the lobsters go away. Perhaps global climate change reduces their numbers or perhaps the current abundance proves to be a digression from the normal. Either way, fishermen are forced finally from their ancient traditions back to the land. Their properties are sold and McMansions fill the coastline until the fishing tradition in Maine is lost forever. Perhaps the wealthy people from away will catch striped bass from their front lawns, perhaps they won’t. Please, forgive me for being dramatic, but I believe that the future of Maine’s fishing tradition is dependent on bringing some sort of balance back to the system. Fishermen have survived historically by having options and being able to adapt. Stock failures and the resulting regulations have taken the adaptability away.

In the second hypothetical future the current shift towards ecosystem based fisheries management continues. Fishermen, policy makers and citizens of Maine realize the fragility of the coastal economy and take action. People dedicate themselves to restoring some sort of balance to a disrupted ecosystem. Striped bass roil at the surface of Merrymeeting Bay as they devour abundant alewives. Fishermen catch lobsters in the summer, cod in the winter, and perhaps somebody sells a striped bass in their fish market. Atlantic salmon return to the Kennebec River. While there is no commercial fishery, people can rest assured that they haven’t exterminated this incredible fish. It would be naive to suggest that the impacts of climate change will not be felt. However, striped bass and alewives are near the northern extent of their ranges and will likely survive water warming. While salmon might not be so lucky there remains some sort of resiliency to the system. Perhaps lobster return to historical levels, but now an independent fisherman can survive catching cod, or striped bass or any of the other species that would be benefited by improved conditions of Maine’s river and coastal environment.

I hope that this second view of the future is not overly optimistic. Getting there will require understanding, compromise and sacrifice by various groups throughout the state. Fishermen and scientists and property owners and politicians will have to work together. The driving force should be an understanding that our oceans and rivers are complex, socioecological systems that require flexibility, adaptability and creativity to manage. There will be failures. Perhaps we can learn a lesson from our friend the alewife as it fights its way upstream; persistence. The past centuries have seen the decline of anadromous fish in Maine’s rivers. The coming decades will decide if the alewife will disappear forever or be the catalyst for building a productive and resilient ecosystem for the coast of Maine.

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