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Recovery Strategy for the Vancouver Lamprey (Lampetra macrostoma) in Canada (Final)

6. Critical Habitat

Identification and protection of critical habitat is vital for management of species at risk. While defining critical habitat is one of the most challenging aspects of species management, it is essential to ensuring a species’ long-term survival.  This rationale is central to endangered species legislation in general, and specifically to the Species at Risk Act, where critical habitat is defined as:

“…the habitat that is necessary for the survival or recovery of a listed wildlife species and that is identified as the species’ critical habitat in a recovery strategy or in an action plan for the species.” [s. 2(1)]

The need to designate and protect critical habitat is clearly recognized by scientists, resource managers, and the general public.  Despite its complexity, the core issue is the same for all species: to determine the role of habitat in population limitation, and to answer the question, How much habitat is necessary for the survival and recovery of a listed wildlife species?

6.1 Identification of the Species’ Critical Habitat

At this point, it is possible to indicate some habitats that are important.  For example, it is understood that as an ammocoete, Vancouver lamprey inhabits fine sediments in the littoral zone and in the lower portion of some tributaries.  It is also known that during spawning, Vancouver lamprey aggregate over shallow gravel beds at the mouths of creeks and along lake shores.  Clearly, these habitats, or portions of them, may feature in the identification of the species’ critical habitat.  However, due to a number of information gaps, we are unable to provide a defensible demarcation of critical habitat at this time. 

6.2 Schedule of Studies

Very little is known about Vancouver lamprey.  We therefore propose undertaking a series of tasks to allow delineation of critical habitat for the species. The precise nature of each task will be developed in one or more Action Plans.  These studies are projected to be undertaken in the next five years, and reassessed in conjunction with updates to the recovery strategy.

Habitat Use.-- The initial task in identifying critical habitat for Vancouver lamprey is to develop a better understanding of habitat used by different life stages.  A description of the basic habitat associations for each life stage is a core information need for defining critical habitat (Rosenfeld and Hatfield 2006).  The first step in defining habitat use would be to synthesize and report on information collected during previous investigations, such as those by R. Beamish.  There is a general understanding of habitat types used by Vancouver lamprey ammocoetes and spawning adults.  A more precise definition would be beneficial.  Where possible, habitat requirements will be defined in terms of microhabitat components such as water depth and velocity, and substrate type and condition.  Observations on spawning locations would be useful for identifying the characteristics of habitat suitable for spawning, and candidate sites for critical habitat.  Similarly, sampling of littoral sediment to determine the distribution and density of ammocoetes would contribute to identifying locations and characteristics of habitat likely to be important for larval lamprey.

Habitat Availability.-- A related task is to review historic and current habitat availability for Vancouver lamprey.  Information on the extent and distribution of different habitat types available to a species is also a key component of critical habitat delineation.  Studies are required that describe abundance and distribution of different habitats in the wild.  Where possible, historic habitat availability should be explored to help provide context for the present condition, and the final delineation of critical habitat.

Population Abundance.-- Another task will be to review historic and current population abundance, as part of the process of setting recovery targets.  Both the current and historic population abundance provide meaningful context for the recovery target, though we recognize that historic abundance may be difficult to ascertain with accuracy.

Recovery Targets.-- Clearly defined population recovery targets for each life stage are integral to the identification of critical habitat, because the quantity of habitat designated as critical must be related to a population benchmark (Rosenfeld and Hatfield 2006).  Setting recovery targets may require several steps and the collection of several pieces of information.  Recovery targets may be based on rules of thumb (e.g., Thomas 1990; IUCN 2001; Reed et al. 2003), numeric analyses such as population viability analysis (PVA; Morris and Doak 2002), or a combination of techniques.  For species such as Vancouver lamprey, where relatively little information exists and additional information takes a long time to collect, it may be beneficial to use targets based on rules of thumb.  However, it is nevertheless valuable to examine such targets by assessing key population parameters (e.g., survival and fecundity) and to undertake specific population modeling (e.g., elasticity analysis, see Gross et al. 2002) to explore which life stages are most limiting to lamprey abundance.

Relationship Between Habitat and Abundance.-- Designation of critical habitat requires quantitative relationships between habitat and abundance, to establish the amount of habitat required to achieve a population recovery target (Rosenfeld and Hatfield 2006).  Developing such a relationship is not a straightforward task and may need to rely, at least in part, on expert judgement.

Define Critical Habitat.-- The final step in delineating critical habitat is to use population targets and relationships between habitat types and abundance to determine how much of the different habitats is required to maintain a viable population of Vancouver lamprey, and to then identify the specific locations of these habitats in the wild.

6.3 Examples of Activities that are Likely to Result in Destruction of Critical Habitat

Until critical habitat is formally delineated it is not possible to provide specific guidance on which activities are most likely to destroy critical habitat, other than in very general terms.  For example, lamprey have habitat requirements similar in many respects to those of salmonids, so activities likely to degrade salmonid habitats can be expected to also have negative impacts on lamprey.  The more general threats to some of the important habitat types for Vancouver lamprey are discussed in Section 3.  These threats and activities should be assessed for their effects on critical habitat and the steps necessary to mitigate negative effects.