Morrison creek lamprey (Lampetra richardsoni var. marifuga) recovery strategy: chapter 2
Species Information
Common Name: Morrison Creek lamprey
Scientific Name: Lampetra richardsoni var. marifuga
COSEWIC Assessment Summary: May 2000
COSEWIC Status: Endangered
SARA Status: Endangered, June 2003
COSEWIC Reason for Designation: Endemic to British Columbia, this single, small population is susceptible to habitat loss from urban development and highway construction.
Canadian Occurrence: British Columbia
COSEWIC Status History: Designated Threatened in April 1999. Status re-examined and changed to Endangered in May 2000. May 2000 assessment was based on new quantitative criteria applied to information from the existing 1999 status report (Beamish et al. 1999).
Background
1. Description of the Species
- 1.1 General Biology
- 1.2 Distribution
- 1.3 Abundance
- 1.4 Importance to People
1.1 General Biology
Lampreys are members of the Superclass Agnatha, jawless fishes. Lampreys are distinguished by a cylindrical, eel-like, scale-less body and a round suctorial mouth armed with a series of sharp, horny teeth. They have a small caudal fin, and long dorsal fin, often with two distinct parts; they have no paired fins (Figure 1). The skeleton is cartilaginous, a trait that has contributed to a poor fossil record. Lampreys have seven pairs of gills in the form of gill pouches, each with an individual opening to the outside (Scott and Crossman 1973). There are about 38-45 species of lamprey within nine genera, depending on the current interpretations of experts (Gill et al. 2003; ITIS 2005).
Figure 1. Photograph of Morrison Creek lamprey, taken in spring 2005. This specimen is ~ 12 cm total length, and is thought to be three to four months post metamorphosis. Photo by Jim Palmer.
Lampreys are generally distributed in temperate marine and freshwaters; the worldwide distribution is predominantly in the Northern Hemisphere (Scott and Crossman 1973). About 1/3 of lamprey species are anadromous. As adults, lamprey species are either externally parasitic of other fish species, or do not feed at all. All lamprey are semelparous and die soon after spawning (Larson 1980).
Lampreys are difficult to age reliably (Beamish and Medland 1988; Kostow 2002). They have a distinct larval phase followed by metamorphosis (Scott and Crossman 1973), but time to metamorphosis (sometimes called transformation) varies among species. Larvae, called ammocoetes (Figure 2), live in burrows in stream and lake sediments (Scott and Crossman 1973). Ammocoetes have sightless eyes; teeth and oral disk are absent, and the mouth is covered with an oral hood. Ammocoetes feed by filtering microscopic plant and animal material and organic detritus through the oral hood (e.g., Manion 1967; Moore1973, 1980; Sutton et al. 1994; Mundahl et al. 2005).
In British Columbia there are four described species of lamprey (Beamish 1985). Lampetra richardsoni is a non-anadromous, non-parasitic, freshwater-resident species commonly found in streams. The Pacific Lamprey, L. tridentata, is anadromous and parasitic; it is commonly found in coastal streams and marine coastal areas. L. ayresi is anadromous and parasitic. It can be very abundant in the Fraser River, and is common in the Strait of Georgia during its parasitic phase. Little research has been done on this species outside the Georgia Basin. L. macrostoma, originally described by Beamish (1982), is parasitic and assumed to be derived from L. tridentata. It has been reported only in Cowichan and Mesachie lakes (Beamish 1998).
In Morrison Creek, Vancouver Island, there are three distinct lamprey types (Beamish 1985), including one that does not fit within the description of the four species noted above. One type is L. tridentata, which can be readily distinguished both as an ammocoete and post-metamorphosis (Beamish 1985). The other two are forms of L. richardsoni that can be distinguished from each other only at certain stages of development (Beamish 1985).
One of the L. richardsoni types is the “normal” life history form. This type lives entirely in freshwater, is non-parasitic and does not feed as an adult. It undergoes metamorphosis in September, overwinters in the gravel, and spawns and dies the following May to July (R. Beamish, pers. comm.). Ammocoetes live in burrows in fine stream sediments for an estimated three to seven years, and grow to about 13 cm in length. Reproductive adults are slightly smaller than the ammocoetes, usually 8 to 12 cm in length, and dark brown or black in colour (McDermott 2003). Teeth are present on the oral disk, but quickly wear and become blunt (Beamish 1985).
The second type, discovered in 1977 (Beamish 1985), is believed to be a derivative of L. richardsoni and has been labelled L. richardsoni var. marifuga (Beamish 1987). Most of what we know about the life history of this type has come from lab-based studies (Beamish 1987). Distinguishing between ammocoetes of L. richardsoni and L. richardsoni var. marifuga is not yet possible as ammocoetes have not been unequivocally matched to each form. Individuals become distinguishable shortly after metamorphosis. The marifuga variety is notable because its teeth remain sharp, it apparently feeds by parasitizing a variety of fish, lives for up to one year longer, and retains a silver colouration until the end of September prior to spawning. It is commonly, though not always, larger (i.e., 15 to 18 cm) at spawning than the normal variety (Beamish 1985, 1987; McDermott 2003), indicating that individuals feed after metamorphosis. Mating or feeding behaviour have not been observed in the wild, though adults of L. richardsoni var. marifuga readily attacked a variety of live and dead fish in the lab (Beamish 1985). As such, it represents an important example of a parasitic form derived from a non-parasitic form. The timing of spawning and ammocoete rearing is apparently similar to that of L. richardsoni.
It remains unclear whether the two L. richardsoni forms in Morrison Creek are different life history phenotypes of the same species or separate lineages (Beamish 1985; Beamish et al. 1999). Identical allelic frequencies (Beamish and Withler 1986) suggest that the two belong to a common gene pool that produces both adult life history types. Detailed genetic analysis and additional field work is recommended to help resolve this issue. At present, evidence seems to favour the idea that they are distinct life history forms within a single lineage (i.e., a polymorphism). Multiple life history forms are common within other fish species, but very few lamprey populations have more than one life history phenotype (Beamish 1987) and this is the best documented and the only one known to produce multiple life history types on an ongoing basis. Size differences are thought to prevent cross-breeding between L. richardsoni and L. richardsoni var. marifuga (R. Beamish, pers. comm.).
Based on morphological characteristics, it is possible that L. richardsoni var. marifuga is a hybrid between L. richardsoni and L. ayresi. This hypothesis is deemed unlikely (R. Beamish, pers. comm.): L. ayresi has not been observed in Morrison Creek, and L. richardsoni var. marifuga shows no physiological tolerance to sea water (Beamish 1985), providing some evidence against the hypothesis.
In developing this recovery strategy we refer to “Morrison Creek lamprey” as all L. richardsoni within the Morrison Creek drainage, under the assumption that L. richardsoni var. marifuga is not a distinct self-sustaining lineage, but rather is a life history form within a unique, polymorphic L. richardsoni population. Strategies are therefore put forward for the Morrison Creek L. richardsoni population as a whole.
1.2 Distribution
The Morrison Creek lamprey is an extreme endemic. It is found only in the Morrison Creek watershed, a tributary to the Puntledge River on Vancouver Island, British Columbia (Figure 3). Morrison Creek is somewhat unusual for this area because its headwaters are dominated by wetlands, but the reasons for this life history form evolving only here are not understood. It is possible that the unique features of the watershed (extensive headwater wetland habitat, large groundwater inflows and stable temperatures and flow) were instrumental in the evolution of this variety. Distribution of lamprey within Morrison Creek is not known, particularly in the headwater wetlands that are difficult to sample. However, salmonids have been observed in the upper watershed almost to its upper limits, and lamprey have been observed in areas inaccessible to coho (J. Palmer, pers. comm.). Lamprey are good swimmers, commonly migrating to the headwaters of streams (Scott and Crossman 1973), so there is no a priori reason to expect lamprey to be restricted in their distribution within Morrison Creek. Ammocoetes may be more plentiful in the wetland habitats (R. Beamish, pers. comm.). Attempts to find Morrison Creek lamprey within the Puntledge River and other rivers in the area have not been successful (R. Beamish, pers. comm.).
Figure 3. Distribution of Morrison Creek lamprey. (Map base obtained from Ministry of Energy, Mines and Petroleum Resources.
1.3 Abundance
There has been little research done on Morrison Creek lamprey, and at no time has a population estimate been made of this variety. It was regularly captured during early work (Beamish 1985), and adults continue to be captured and enumerated at a smolt counting fence operated by volunteers (J. Palmer, personal communication). At no time have the counts been high (usually < 100 individuals), but there has no been no indication of large population fluctuations or declines (Beamish 1985). Catch per unit effort has not been used to assess trends because sampling was not conducted uniformly across years. Based on personal experience with sampling lamprey in BC, R. Beamish indicates that the marifuga variety is rare within the Morrison system. There is no evidence that the variety is in decline, however, no firm conclusions can be drawn with the current data.
1.4 Importance to People
The special significance of the Morrison Creek lamprey is primarily its scientific value (e.g., see Section 16 for a partial list of scientific literature). There is no commercial value to the variety. As a group, lamprey are not generally well-regarded because some species are parasitic on salmonids or other highly-valued species. The fact that introduced lamprey have caused considerable harm in other systems (Fuller et al. 1999) likely adds to lamprey's poor reputation. Conversely, others view Morrison Creek lamprey as a member of the native fauna, with its own intrinsic values including its contribution to biodiversity, education, ecological role and science. As a scientific subject, the Morrison Creek lamprey is of considerable interest for its extreme endemism and unique presence of more than one life history form. It has been suggested that Morrison Creek lamprey may represent a transition between parasitic and non-parasitic forms (Beamish 1985). The cultural value of Morrison Creek lamprey to First Nations has not been investigated for this report, though it should be noted that the larger Pacific Lamprey has significant cultural value for First Nations people in some regions (Close et al. 2002). Presence of lamprey is generally a good indicator of habitat quality and suitability for Pacific salmon (R. Beamish, pers. comm.).
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