Merrymeeting Bay / Kennebec Estuary Research Program (Bowdoin)

Luke Fairbanks and Scot McFarlane .
Population Dynamics and Natural History of Smelt
(Osmerus mordax) in Merrymeeting Bay

 

Introduction

Merrymeeting Bay has an interesting ecological and cultural history of the rainbow smelt (Osmerus mordax). Smelt are small, carnivorous fish that occurs throughout the coastal Atlantic Ocean. Smelt average 18-23 cm in length, and can be identified by their predominantly greenish color with colorful iridescent reflections along their sides and bellies (hence the �rainbow� in their name).[1] For the brave, smelt may also be identified by their curious smell, which is often likened to cucumbers (hence �smelt,� and Osmerus—meaning odorous). Additionally, smelt are an exceptionally tasty fish (traditionally pan-fried whole), which have historically supplied commercial fisheries throughout the region. They are anadramous, meaning that they live part of their lifecycle in the open ocean, and then return to freshwater to spawn. However, strictly freshwater populations of the species also exist, and reside in landlocked lakes and river systems.

Within Merrymeeting Bay, smelt have played a major role in shaping the ecology and fishing culture of the system. They are voracious predators, and utilize their relatively large mouth and numerous teeth to feed on a wide variety of organisms, including amphipods, shrimps, and many different small fishes. But smelt themselves are also important prey for a number of larger predatory species. In Merrymeeting Bay, anything from cormorants to white perch may feed upon the fish. They are especially important as a prey species since they are the only anadramous fish that spends time in the system during the winter months. Smelt generally overwinter in estuaries in order to avoid cold ocean waters (they produce antifreeze agents within their bodies to withstand subzero seawater temperatures), and subsequently tend to overwinter within the Merrymeeting Bay system, migrating as far as the head of the tide throughout the season.

After spending the winter within Merrymeeting Bay and its rivers, the smelt spawning run begins shortly after ice break in the Spring. It is the earliest anadramous fish run in Merrymeeting Bay, preceding that of alewives and shad. The smelt move through the bay and into its rivers and tributaries, traveling upstream where they typically spawn near the head of the tide, where their small yellow eggs can be seen coating rocks along the shore and bottom. Occasionally the fish may be moving so frantically upstream that they will get caught in shallow-water rocks or gravel.

Smelt Fishery and Market

Smelt have long been a popular species for both commercial and recreational fishermen. Centuries ago smelt were not regarded as an important food fish, despite their extreme abundance. Yet Native populations did exploit the resource. Kendall (1927) quotes Capt. John Smith in 1622 stating that �of Smelts there is such abundance, that the Salvages doe take them up the rivers with baskets, like sives.� The importance and popularity of smelt increased during the late 19^th century, and the Maine fishery expanded, utilizing a number of technologies—hook and line being the most important. Foster and Atkins (1867) wrote:

During the winter the smelts are caught with hooks through the ice or with traps or weirs. They yield a large amount of food, a great many thousand of them being taken and marketed during the cold weather, and a few being for sale nearly every month in the year. In quality they have no superior among all the inhabitants of our waters, unless it be the white fish.

Specifically, they go on to describe the Kennebec smelt fishery, which consisted of specialized �half-tide� weirs used only for smelt during their unique fishing season (Atkins 1884). The average catch of such weirs was around $300-$400 annually. During the winter the fish were principally taken in bag nets below the ice (Figure 1).  Additionally, gill nets were unique to the Kennebec fishery, and �a great many of these were used in small tributaries of Merrymeeting Bay� when the fish were larger (Atkins 1884). Although Foster and Atkins had no total estimate for the value of the entire Kennebec smelt fishery, they pointed out that the �smelts are, however, of no small importance.� Atkins (1884) mentions that at least 90 percent of smelt landed in Maine were shipped to market out of state.

            In 1927, Kendall recounted the preceding few decades of the Maine smelt fishery. He mentions that ice fishermen were receiving four to five cents per pound landed in 1888 and that much of the fish was shipped to market in Boston and New York. Statewide harvests remained relatively stable, hovering near 100,00 pounds between 1897 and 1904, and peaking at 1,029,900 pounds (valued at nearly $102,000) in 1903—the same year Goode (1903) stated that:

The Smelt is, indeed, one of the most important fishes of the Northern United States. It is by far the most important river fish in Maine, easily surpassing the economic value the Salmon, Shad, Alewife, and other species that enter the fresh water.

Maine landings then dropped to only 627,707 pounds in 1924 (with the exception of large catches in 1910-11). However, the market prices increased throughout this period to 22 cents per pound, demonstrating the maturity of the market. The decrease in catches mirrored a growing concern over the fish stocks. Many believed it was brought on by overfishing, as a great many fish were being taken by weir and net, especially during the spawning season. Similarly, Atkins (1884) voiced concerns over the decreasing size of an average smelt.

            In the 20^th century, commercial catches continued to decline. A number of factors may have effected smelt stocks, including pollution (acid rain kills smelt eggs), overfishing, and dam construction (although smelt are not as negatively affected by dams as other species such as salmon, since they spawn further downstream). Regardless, 20^th century commercial landings peaked in 1966 at 162.8 mt, then declined to a low of 1.3 mt in 1988. Harvests increased briefly to 27.1 mt in 1992, but since 1998 have only averaged 0.14 mt. The commercial smelt fishery in Maine is now nonexistent.

            However, recreational smelt fishing has historically been very popular, and continues to be. Ice fishing is done during the winter (primarily in shacks), while a hook and line fishery exists in the fall and dip-net fishery exploits the fish during their spring runs. As far back as 1800s the ice fishery was very popular. Kendall (1927) quotes an 1884 American Angler article stating that �the people of Maine look upon smelt fishing as the sport of the year, and they come from miles about the country to enjoy it.� Similarly, out of state tourists took advantage of the fishery, boosting the Maine economy in winter months.

            Today, the recreational smelt fishery, and especially the ice fishery, is a part of Maine�s traditional culture. Smelt camps are open in the Merrymeeting Bay system throughout the winter months, and in total the Maine fishery supports thousands of fishermen. The recreational fishery is not only a favorite Maine pastime, but it is an important part of Maine�s fishing (and tourism) economy. Recent years have seen increased abundance of smelt within the Merrymeeting Bay system as the Androscoggin and Kennebec rivers have begun to recover from decades of heavy pollution. One report estimated the 1984 annual economic impact of the Kennebec recreational fishery at a minimum of $630,000—with the winter fishery being an important component of the calculation (Vanderweide and Ellis 1986). The total impact is likely even higher today. Similarly, a 2002 study stated that Maine has a net gain of 1,075 fishing days per year from out of state fishermen (Ditton et al. 2002). Increased smelt abundance combined with the popularity of the fishery could draw even more tourists to the Merrymeeting Bay region, providing a slight tourism boost during the winter season.

Methods

Winter sampling

            As noted in the introduction, ice-fishing for smelt is a popular pastime around Merrymeeting Bay.  When the ice is thick enough, or even when it is not, small communities develop overnight as people put up their shacks for the wintertime.  As climate change impacts Maine fisherman, the date that it is safe to go out on the ice has gotten later and later.  This has adversely affected the local economies that rely on the revenues of visiting smelt fisherman.  At one public camp in Bowdoinham, Jim McPherson even took the step of building smelting shacks that floated so he could put the shacks out earlier during the warmer winters.  In a typical year, smelt shacks are usually available to rent by the beginning of January (Figure 2). 

            The shacks are rented by each tide.  For about fifteen dollars, a person can rent a shack with a wood stove, bait, and tackle provided.  While it is a topic of debate among fishermen, the best fishing tends to be around the strongest tides of the full moon.  Fishing also varies depending upon whether the tide is incoming and outgoing and the location of the shack.  The standard method for fishing is to have a wall of lines with one or two hooks on each line (Figure 3).  Small, 1cm pieces of bloodworms are cut and put on the hooks.  The depth of the bait should also be varied since smelt will often school at specific depths.  Claire Enterline of the Maine Department of Resources points out that the larger female smelt are usually caught closer to the bottom, while the smaller males are found closer to the ice. 

Spring Sampling

            Once the ice begins to melt towards the end of March, the smelt awaken from their slumber and spawn.  Smelt are known to spawn at the head of tide in freshwater streams in areas with little silt.  Where smelt are most prolific, their eggs can be found covering rocks and masses of eggs float along the bottom.  Mike Brown of the DMR notes that prolific runs of spawning smelt can be found in the Kennebec River near Augusta.  Smelt are caught there by simply throwing out weighted treble hooks and quickly reeling them in with the hope of snagging one of the many smelt in the river. 

            Given that our winter sampling occurred in the Cathance River, we sought to compare the winter population to the spring population of spawning smelt.  While there was no visible evidence of smelt spawning, we assumed that smelt would spawn at the head of the tide.  Using a fyke net, which traps fish in smaller and smaller hoops, we covered the entire channel running up the Cathance to catch as many smelt as possible (Figure 4).  Our sampling plan faced several hurdles.  Early in the spring, large chunks of ice remained in the system, threatening to destroy our net and large amounts of debris at times filled up the entire net (Figure 5).  Also, the tidal portion of the Cathance ends abruptly at a waterfall, which may makes for greater tidal variation than the smelt typically spawn in.  Finally, the floor of the Cathance has a significant amount of silt, which may also prevent smelt from spawning. 

Aging

            In order to better understand the dynamics of the smelt population in Merrymeeting Bay, we undertook the project of aging a sample of the smelt that we had caught.  In many ways, aging smelt is similar to counting the rings of a tree to tell its age.  Scales were removed from below the dorsal fin, cleaned, and placed on microscope slides.  Under the microscope, scales reveal a number of circular lines known as �circuli.�  The circuli extend in a complete circular line, however, when the circuli form partially complete circles this is indicative of a new year�s growth and those sections are called �annuli.�  Finding annuli can be difficult, and at times subjective depending on the clarity of the circuli, but on the whole aging can reveal some interesting trends (Bailey 1964). 

Conclusion

            Our study of smelt revealed a sizeable population in Merrymeeting Bay, though far from the vast quantities that it once sustained.  Though we tried to fill in some of the gaps, our study also showed us how much remains to be known about the population dynamics of this vital fish.  We caught more males than females, but this has to do with the fact that males move around more and are thus more likely to be caught.  Likewise our results confirmed that females tend to be larger than males (Graph 1 & Figure 6).  Of the smelt that we aged, there was roughly an equal amount of two-year old and three-year old fish (Table 1).  During our spring sampling we caught zero smelt and saw no sign of spawning activity along the upper portion of the tidal Cathance.  Though we caught numerous other fish, including many anadramous alewives, there were no smelt (Table 2). 

            Without further research, it may be impossible to adequately protect smelt from the many threats that they face (Figure 7).  The fact that there are virtually no regulations for smelt fishing in Merrymeeting Bay suggests that people prefer to assume that the population is stable, rather than risk limiting access to a valued resource.  If smelt do indeed overwinter on the Cathance, but spawn elsewhere, a tagging study would be very useful to find out where they actually spawn.  One of the few people currently doing research on smelt is Claire Enterline, who is using a tag study to help determine the threats that smelt face throughout the Gulf of Maine.  Understanding both the threats and also the success of smelt�s continued presence could help us to better understand Merrymeeting Bay as whole.  The success of other endangered species such as shad and salmon is directly connected to the story of smelt.  In the meantime, smelt continue to play a key role in the culture of Merrymeeting Bay and the communities that depend on the smelt�s annual return to our streams and rivers. 

 

Tables, Graphs, Figures

 

 

Age Class	Sex Ratio (F/M)	Average Length (cm)	Number
2	0.09	14.7	11
3	0.43	17.4	14

Table 1: The age classes, sex ratios, and sizes of 25 smelt taken from the Cathance River during winter sampling. 

 

 

Fish Species	Number
Spotail Minnow	185
White Sucker	19
Longnose Sucker	6
American Eel	3
White Perch	19
Yellow Perch	4
Alewife	41
White Catfish	38
Smelt	0

Table 2: Results from Fyke net sampling on the upper Cathance river April 29, 2009.  Despite catching over 300 fish including, numerous anadramous alewives, no smelt were found. 

Graph 1: Average fork length (cm) of male and female smelt taken during winter sampling.  Numbers in parantheses indicate smelt counts and error bars represent standard deviation.

Figure 1: Though this print is of the Penobscot River, similarly large smelt fishing ventures took place in Merrymeeting Bay.  (www.noaa.gov)

Figure 2: Map of Merrymeeting Bay and public smelt camps.  (From Maine DMR)

Figure 3: Winter sampling on the Cathance River at Riverbend Smelt Camps.  Lines are dropped from the wall and baited with bloodworms. 

Figure 4: Spring sampling on the upper Cathance River at low tide.  The fyke net is placed across the entire channel to catch all spawning fish. 

Figure 5: Removing debris from the fyke net.  Note the waterfall in the background that prevents fish from moving further upstream. 

Figure 6: An example of sexual dimorphism in smelt, females tend to be much larger than males. 

Figure 7: Smelt endure a plethora of obstacles in their fight to reproduce in the spring.  This picture shows two threats to smelt survival: the parasite on the smelt�s head and the fishermen that caught the fish. 

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