Wednesday, September 10, 2008

The Chestnut Lamprey

Lampreys are a fairly unique class of aquatic vertebrates with an apparently ancient lineage. Every description I’ve read identifies them as superficially similar looking to eels, but lacking a jaw and instead having a round, sucking disk mouth (Cross and Collins 1995, Wikipedia, the Great Lakes Fishery Commission, etc.). That is to say that they are elongated, have no scales, and have spine-less fins. However, the resemblance is pretty much completely superficial. In fact, lampreys are not even true fish (Cross and Collins 1995, Tree of Life), and in 2006 researchers found a fossilized lamprey that was virtually indistinguishable from the modern animal (article about the find) from 360 million years ago. That is way back there, when fish were just evolving jaws.

Lamprey life-history is fairly straightforward...for an amphibian (which it isn’t). The larvae are called ammocoetes, and live in mucky sediments consuming microorganisms (at one point, it was thought these were a totally different species). After 5-7 years of this, they grow eyes and a new mouth, get bigger and learn how to swim. Then they spent ~18 months swimming around and sucking the blood out of fish large enough for them to latch onto (this varies tremendously by species, Chestnut lampreys, the Kansas Threatened species I’m gradually getting to, do not survive more than a year and are adults only a very short amount of this time). Adults then move upstream into smaller streams and reproduce. Reproduction occurs by spawning (egg and sperm release) into shallow, excavated depressions in gravel beds, and the hatched offspring move downstream and spend much of their lifespan in the benthos.

Lampreys are typically thought of as blood-suckers. Indeed, many of the most well-known members of this are fish parasites that kill their host and cause untold economic damage. The introduction of sea lampreys into the Great Lakes by the construction of locks and canals for shipping essentially destroyed the fishing industry in the lakes and devastated the native trout species (probably more economic cost from that than all the benefit they’ve provided). According the Great Lakes Fishery Commission “before sea lampreys entered the Great Lakes, Canada and the United States harvested about 7 million kgs. (15 million lbs.) of lake trout in lakes Huron and Superior annually. By the early 1960s, the catch was only about 136,000 kgs. (300,000 lbs.). The fishery was devastated.”

With all that context, why is there a lamprey species listed as a Threatened species in Kansas? Well, I’m still not sure. The Chestnut Lamprey (Ichthyomyzon castaneus) appears to occur sporadically, but widely, across the Eastern United states. Early literature describes them as “little known” (Jordan 1918). Hall and Moore (1954) considered them rare, and were apparently surprised to be able to find them easily to conduct some fairly technical taxonomic studies (apparently a lot has been made about their teeth?). In 1973, the Kansas Academy of Sciences (KAS) published a list of Rare, Endangered and Extirpated Species in Kansas, and included the Chestnut lamprey as a species “Endangered in Kansas but not nationally” because its status was uncertain and no records had been collected since the 1950s. They recommended stabilizing flow and minimizing turbidity on small, high-gradient streams. Kansas T&E laws date from 1975, and I suspect but cannot confirm yet that the KAS list was adopted en masse when the state law went into effect. So apparently the species was being found with relative frequency prior to the 1950s, then stopped being found anywhere in Kansas except in the main-stem of the Missouri and Kansas Rivers. There’s a nice-looking map on Natureserve that seems to indicate the species is imperiled several places in its range, but I’ve got a touch of color-blindness and therefore I can’t really interpret the map very well (feel free to do so yourself).

Hall and Moore (1954) also described the Chestnut Lamprey’s ecology and habits in Oklahoma, suggesting that this might be one of those native species that actually benefits from the construction of large reservoirs. This is because large fish moving upstream are forced to stop at the barriers presented by reservoirs. Where they congregate, the Chestnut lamprey is able to find abundant food, and their larvae are able to survive better because of the removal of silt. However, the construction of those dams in Oklahoma also corresponds to the species disappearing in Kansas (~1950s-60s). I have a hypothesis that the lamprey throughout the Ark basin was a single, massive metapopulation that became fragmented after the construction of the dams and was subsequently wiped out by random, local, events (i.e., feedlot runoff in the Neosho basin killed hundreds of thousands of fish in the Neosho Basin).

These days, the species if found in Kansas only in the Missouri River and the Kansas River below a dam in Lawrence. That’s an extremely limited range. Cross and Collins (1995) also indicate an active record in Cherokee County (extreme SE Kansas on the Ozark Plateau). That’s actually an area of intense heavy-metal pollution due to mining activities over the past hundred or so years, and I suspect if any lampreys exist, they survive in Missouri and only occasionally wander into Kansas. The only designated critical habitat for this species in Kansas is the Missouri River, and as far as I know, KDWP is not taking any special actions or precautions for the species. This is one of those species I don’t know a lot about, so as I read more, I may write more on it.

Jordan, D.S. 1918. The Freshwater Lamprey’s of the United States. Copeia, 64: 93-96

G.E. Hall and G.A. Moore. 1954. Oklahoma Lampreys: Their Characterization and Distribution. Copeia, 2:127-135

Kansas Academy of Science. 1973. Rare, endangered and extirpated species in Kansas. I. Fishes. Transactions of the Kansas Academy of Science 76:97-106.

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