Volume 3, Number 4
Scientific Value of Keeping Native Fishes In Aquaria
Lawrence M. Page, Principal Scientist
Center for Biodiversity, Illinois Natural History Survey, Champaign, IL 61820
Fishes are kept in aquaria for a variety of reasons. Most aquarists keep
fishes because they enjoy observing the tremendous diversity of body shapes,
colors, and behaviors. Others keep fishes for the explicit purpose of learning
something new about them. Keeping only a few species of fish can quickly teach
an aquarist and his/her family some valuable lessons about the natural world.
Our native fishes are quite diverse – about 800 species are found in the
freshwaters of North America – and they show a great variety of morphological
designs and behaviors.
Keeping fishes in aquaria has led to many original observations. It is one of the best methods for making scientific discoveries about fishes, which can be extremely difficult to study in streams and lakes. In fact, some fishes are nearly impossible to study in detail in the bodies of water in which they normally are found. For example, fishes that live in turbid rivers cannot be seen by human observers who are either above or in the water. Fishes that live in clear water can be observed from a stream bank or by someone with a snorkel, but often they are extremely uncooperative with a person trying to study them. In aquaria, conditions can be controlled to simulate natural conditions and may lead to observations that otherwise would not be made.
Although sometimes difficult to observe even in aquaria, spawning behaviors can be particularly fascinating and relevant to species protection. Some fishes spawn by scattering eggs, some lay eggs in secluded places and guard them, others give birth to living young. One group of native fishes on which our knowledge of spawning behaviors has grown greatly from aquarium observations are darters. With about 180 species, darters are one of the two most diverse groups of North American fishes. (The other group, the minnows, contains about 250 species.) Aquarium observations on darters have revealed a variety of reproductive behaviors. Some bury their eggs in the substrate, some attach them to plants or the sides of rocks, and some sequester them under rocks and guard them. We know now the breeding habits of 103 species of darters. Only 25 of these species have been observed in nature; the other 78 have been observed only in aquaria.
Females of some of the egg-guarding species of darters prefer to lay eggs with males that already are guarding eggs in their nests rather than spawn with males without eggs. They shun males at least to some degree that have not yet demonstrated that they can successfully guard eggs. Males of these species compete for these choosy females and, in some species, have evolved morphological traits that can make them more attractive to females. They have evolved structures on their fins that look very much like eggs. These egg-mimics can attract females to nest sites even though no eggs are present. Although not always this spectacular, other amazing behaviors are shown by North American fishes, and many of these behaviors are known only because they have been observed in aquarium-held fishes.
In the United States, 70 species of fish are listed as federally threatened or endangered because of habitat loss and other forms of environmental degradation. This depressingly large number of endangered fishes exists because people do not care or know enough to demand that land be developed in a way that protects habitat for our native plants and animals. The more that we know about our native fishes, the more we will appreciate them for their beauty and their habits, and the more we will want to protect their environments.
Scientists make excellent use of aquarium observations. In fact, we would know far less about our native fishes if we did not keep them in aquaria. Aquarists enjoy keeping fishes, but our native fishes are the more significant beneficiaries of this activity.
Putting Back the Pieces II
Konrad Schmidt, Nongame Fish Biologist
Department of Natural Resources, Box 25, 500 Lafayette Rd., St. Paul, MN 55155
In the 1960s and 70s, Wisconsin carp control programs treated several streams with fish toxicants which may have eliminated many non-target species. Extirpation is difficult to verify, however, Becker (1983) reported the suspected loss of at least 10 species from treated streams where isolated populations would likely never be naturally reestablished (Table 1).
Table 1. Reported fish extirpations in Wisconsin (Becker 1983).
Species - Population
Northern Brook Lamprey - Tomorrow and Waupaca Rivers: 50 miles of mainstem and tribs
Redfin Shiner - Upper Rock River system: Washington and Fond du Lac Co.
Bigmouth Buffalo - a) Beaver Dam Lake: Dodge Co. b) Rock River: above Watertown
Silver Redhorse - Waupaca River: Weyauwega to mouth Waupaca Co.
Longear Sunfish - East Branch of Rock River: Washington Co.
Western Sand Darter - Waupaca River: downstream of Weyauwega
Rainbow Darter - Waupaca River: downstream to Weyauwega Waupaca Co.
Fantail Darter - Waupaca River: downstream to Weyauwega Waupaca Co.
Least Darter - Waterloo Creek: Dane Co.
Banded Darter - Tomorrow and Waupaca Rivers: Portage and Waupaca Co.
I suspect comparing all available pre and post treatment surveys of these streams would delete some species, but also add several more. Even though this nefarious list will contain almost exclusively nongame fishes, I feel the Wisconsin Department of Natural Resources (WDNR) and NFC, as an advocate, have a responsibility to at least verify extirpation, and whenever possible, reintroduce species to historic localities. Unfortunately, the reality is there will be little funding to support such an initiative and NFC, especially members in Wisconsin, may consider, accepting a larger role.
My proposal generally follows what I did following the 1989 reclamation of
the Upper Knife River watershed in central Minnesota (Schmidt 1990 and 1993). I
recommend the following actions be taken:
1. Organize interested members.
2. Present proposal to the WDNR.
3. Verify and document extirpations.
4. Identify nearest existing populations.
5. Conduct reintroductions.
6. Monitor results.
A general inquiry outlining objectives should be submitted to all offices within the WDNR which may become involved with the project. This would likely include the Bureaus of Endangered Resources, Fisheries Management, and Integrated Science Services. The WDNR will decide whether and how to proceed. In my own experience with the Minnesota Department of Natural Resources (MDNR), I was officially signed on as volunteer which enabled partial reimbursement of expenses, provided unlimited access to all survey files, and issued a permit to collect, transport and reintroduce nongame fishes. Initially in the reintroductions, the Section of Fisheries also assisted with the "loan" of a fish transport truck with a biologist who was actually "double checking" my identification before finally turning me loose.
If the proposal is accepted, verifying extirpations and establishing a final species list can be a very "dry" and tedious task, but probably the most important phase of the project. The Bureau of Fisheries Management should be able to provide a list of all streams which have been treated for carp control. The Bureau of Integrated Science Services maintains a large fish distribution database which contains survey records from approximately 50 percent of the basins in Wisconsin (Fago 1992), and may be able to provide both a before and after species list for the exact reach of treated stream. If no follow up surveys have been conducted since treatment, some field sampling may be required at historic localities. However, whenever a "target" species is found, at least one specimen should be saved for verification and deposited in a voucher collection. Once the species list is finalized, potential sources for reintroduction should be identified and preferably be proximal populations in the same basin which should be genetically similar to the extirpated population. Again, the Integrated Science Services’ database may be able to provide a list of candidate populations.
I would hope the WDNR will permit NFC members to reintroduce most species with a minimal amount of supervision and restrictions. However, I see a few problems and issues which will probably have to be addressed at some point. On the current list of extirpated fishes (Table 1), the redfin shiner and longear sunfish are Threatened, and the western sand darter and least darter are Special Concern in Wisconsin (Schmidt 1996). The Bureau of Endangered Resources will probably support the intent of reintroductions, but will require collection permits which stipulate conditions to safeguard the "seed sources." Fisheries Management would almost certainly be concerned with identification skills and a field proficiency exam may be required. Finally, some species can't be collected in sufficient numbers with gears that will likely be permitted for this project. Electrofishing is probably the most effective method to collect bigmouth buffalo and silver redhorse which Fisheries Management may be able to do incidentally with regularly scheduled activities.
Seines, kick nets, and minnow traps can be very effective on most species in their preferred habitats. During collection, I keep the catch in a flow through minnow bucket which is tethered on a rope off my belt. In transit, I use food coolers up to 96 quarts, avoid over crowding, and provide DC aeration. At the reintroduction site, I temper fish with stream water and select habitats that provide temporary cover and some protection from predators. Ideally, reintroduction stock should be pre-spawn fish collected during cool spring temperatures which will reduce stress and minimize mortality. Finally, follow up surveys should be done every year or two which will confirm whether or not the stockings were a success. Again, at least one “trophy” should be saved for bragging rights, and more importantly, provide the "body of evidence" as proof the reintroduction efforts were successful.
If there is interest within NFC and the WDNR to pursue this project, I would be available intermittently to serve as a consultant and participate with reintroductions and follow up surveys. However, I'm not going to mislead any one by saying this isn't hard and time consuming work which does demand commitment. On the other hand, I also can't express the reward in once again finding fish that I was responsible for "resurrecting."
Becker, G.C. 1983. Fishes of Wisconsin. University of Wisconsin Press,
Madison. 1053 pp.
Fago, D. 1992. Distribution and relative abundance of fishes in Wisconsin VIII. summary report. Technical Bulletin No. 175. Wisconsin Dept. of Natural Resources. 378 pp.
Schmidt, K.P. 1990. Fishes of the Knife Lake watershed in Kanabec and Mille Lacs counties of Minnesota. Minnesota Nongame Wildlife Program. 13 pp.
Schmidt, K.P. 1993. Putting back the pieces. North American Native Fishes Association. American Currents: Spring pp. 22-26.
Schmidt, K.P. 1996. Endangered, threatened, and special status fishes of North American fourth edition. North American Native Fishes Association. 65 pp.
Habitat Preferences Exhibited by
the Gravel Chub (Erimystax x-punctatus)
Lucia Yess, Winona (MN) Middle School Science
Editor’s Note: Anytime our youth (and tomorrow’s future) expresses an
interest in nongame fishes, I am at first impressed with insight far behind
their years. I am also always happy to help guide and encourage their pursuits.
In this case, my part was small, enjoyable, and cost me but one Saturday helping
collect specimens. Through the process, I believe Lucia gained an appreciation
for our little known fishes, their plight, and launched her light years ahead of
her peers. In the future, I hope this learning experience will prove beneficial
in her chosen professional, as an informed citizen, and of course, voter.
Our rivers and streams are an important part of our environment producing
beauty, recreation, transportation, and food among other things. However, a
small change can effect the ecosystem, particularly to the little known members
like the minnows and other nongame fishes. I think it is important to study
these fishes because most people who work with fish generally do not know a
great deal about nongame species. In addition, many of these poorly known
species are having problems with their habitat in the wild. I became interested
in this project because my dad is a fisheries biologist with the U.S. Fish and
Wildlife Service and I have always been fascinated in his work.
I tested one minnow and two darters: the gravel chub (Erimystax x-punctatus), rainbow darter (Etheostoma caeruleum), and banded darter (E. zonale). These fishes were selected because they are all having difficulties with their habitat and were accessible to me. The purpose of my project was to determine the position in the creek these fishes prefer. Habitats studied to determine preferences included: wing dams, a rock piles, and box dams. The habitats were constructed in a simulated creek which used a pump to provide flow.
The gravel chub has been found in four streams in Wisconsin where it has been listed endangered since 1979 (Wisconsin DNR 1999). It prefers to live in streams with permanent flow and eats periphyton (detritus, diatomaceous algae, and bacteria), Triehoptera, plant material, Ephemeroptera, gastropods, and miscellaneous aquatic insects. Gravel chubs grow to slightly over three inches long and have silver sides (Becker 1983). The DNR believes the gravel chub has declined because of fertilizers running off from farm fields which impacts this species habitats and water quality. The nutrients cause abundant aquatic plant growth and muddy waters (Becker, 1983). In Canada, the gravel chub has had similar problems. Canada listed it as endangered in 1985 but removed it from the endangered list in 1987 (www. gravelchub.com). Canadian gravel chubs look exactly like the Wisconsin gravel chub because it is the same species. They are found in only one river in Canada but are hard to collect so it is possible they could be in more streams. The gravel chub prefers streams with permanent flow, clean water, and bottoms free of clay and mud.
The rainbow darter is commonly found in central Wisconsin and prefers clear, shallow water. In one study, 60% of the rainbows were found in pools and 40% in riffles. Rainbow darters are found in streambeds made up of sand, boulders, or gravel. Streams are generally twelve to twenty-four meters wide. They can also live in streams as small as three meters to as large as one hundred meters wide. Rainbow darter’s habitat changes depending on age and if they are male or female. Adult males remain in fast flowing, large, rocky riffles during the winter and after the reproductive period. Adult females like the same habitat as males in the winter. However, before and after the spawning periods, females and young are found in raceways and pools. The young will also stay in the raceways and pools during the winter. The rainbow darter's population has declined due to pollution (sewage) and siltation (Becker, 1983).
Banded darters prefer clear, swift flowing streams with gravel, sand, or rubble. In one study, 50% of the banded darters were found in riffles and 43% in pools. They prefer depths from three to four and a half feet. The banded darter has been found in small streams in southern Wisconsin. Like the gravel chub, they are not found in streams with abundant vegetation (Becker, 1983).
Before collecting the fish, I obtained a special permit from the Minnesota Department of Natural Resources to obtain, transport and possess the fish for study.
I hypothesized the gravel chub would prefer the wing dam over the box dam and
the rock pile because I collected them from a habitat which appeared very
similar. I thought the wing dam’s deflecting flow would help the gravel chub not
waste as much energy trying to stay in one spot.
I believed the banded and rainbow darters would both prefer the box dam because they also would not waste energy remaining stationery in the stream. The box dam had three sides which would provide some shelter from downstream and cross flows.
A simulated creek was constructed and waterproofed with marine paint. Water
was collected from a river and maintained at a temperature of 61 degrees (F).
For each test, the same habitat structure (e.g., wing dams) was placed at three
equally spaced positions along the length of the simulated stream. A filter and
a pump was used to maintain water quality and provide current.
Fish were collected from the North Branch of the Root River (Olmsted Co.) with the assistance of a DNR fish biologist and placed in coolers filled with river water for transport. They were then placed in the creek. Nine tests were done with the wing dam structure, one per day for nine days. A test consisted of blocking fish with dividers in a wing dam area for counting. The rocks in the wing dams were removed and the number of fish were counted. This was repeated for the remaining two wing dams. After nine tests with the wing dam, this procedure was repeated with the box dam and rock pile structures for a total of 27 tests.
Becker, G.C. 1983. Fishes of Wisconsin. University of Wisconsin Press,
Madison. 1053 pp.
Gravel chub visits at habitat structures and locations.
Rainbow darter visits at habitat structures and locations.
Banded darter visits at habitat structures and locations.
Species averages at habitat structures and locations.
wing dam 1-0.3
wing dam 2-2.1
rock pile 1-0.1
rock pile 2 -0.7
rock pile 3-1.7
box dam 1-1.0
box dam 2-1.4
box dam 3-0.2
wing dam 1-5.0
wing dam 2-10.2
wing dam 3-1.8
rock pile 1-3.2
rock pile 2-7.4
rock pile 3-5.9
box dam 1-5.1
box dam 2-9.1
box dam 3-2.8
wing dam 1-3.3
wing dam 2-1.6
wing dam 3-0.4
rock pile 1-1.7
rock pile 2-2.2
rock pile 3-1.6
box dam 1-2.8
box dam 2-1.7
box dam 3-0.9