Non-homing organisms are thought to rely on stable geophysical features (e.g., land-slope), and encounter with distinct attributes of the environment (e.g., landmarks) in a predicable sequence to locate reproductive habitat (e.g., rivers always occur on a coastline). However little is known about how non-homing fishes complete a large-scale migration, as most research has focused on homing fishes that rely on geomagnetic cues to return to a natal spawning site. The invasive sea lamprey offers insight into non-homing migration, as individuals complete a single non-homing migration to rivers following translocation by host fishes in the Great Lakes. In this dissertation, Chapters 2 and 3, are devoted to developing a framework for describing animal behavior from telemetered observations and development of a standardized approach for assessing and filtering VEMCO Positioning System (VPS) data based on an estimate of horizontal position precision (HPE). This methodology was imperative for exploration of the sea lamprey migration with the underwater VPS telemetry technology.In Chapter 3, we described how sea lamprey orient to a coast when in a lake and hypothesized that sea lamprey navigate to the nearest coast by (1) orienting to the local bathymetric gradient and (2) maintain straight movements counter to the local slope to move towards shallow water. Three-dimensional (3-D) paths of migrating female sea lamprey were obtained by an acoustic array with 3 km2 of coverage, centered 3.3 km from the coast in Lake Huron. The findings of this chapter indicate that sea lamprey sampled an area of lake-bottom to assess absolute hydrostatic pressure and to select a heading towards reducing pressure (shallower water). In contrast to natal homing migrations, the sea lamprey appears consistent with non-homing orientation to a general region with a simple set of rules based on local topography.Chapter 4 focused on the sea lamprey migration along a coastline and near a river mouth. Upon reaching a coastline, sea lampreys move parallel to shore. Prior studies indicated the presence of larval odor in river water increased the likelihood that a migrant entered a river. However, it was not known whether larval odor played a role in navigation (guiding the migrant to the river mouth) or mediated habitat selection by labeling the suitability of a river for spawning. In a two-year study using a 2 km2 acoustic array, the 3-D paths of sea lamprey were documented as they approached, entered, or bypassed the Ocqueoc River in northern Michigan, under one of two conditions: (1) low larval odor; and, (2) higher larval odor, created by increased larval abundance plus the addition of the synthetic larval odor components, petromyzonamine disulfate (PADS), petromyzosterol disulfate (PSDS), and petromyzonol sulfate (PZS) to a 1 x 10 -12 M concentration. A coupled hydrodynamic and dye concentration model predicted the hydraulic conditions experienced by each sea lamprey by estimating water conditions (velocity, temperature, etc.) at each fish position and allowed for assignment of whether a position was inside or outside of the Ocqueoc River plume. Encounter with river water appears to trigger localized search, regardless of larval odor content. However, when larval odor was abundant, the migrant was more likely to enter the river. Whether a migrant enters a river, is modulated by the presence of detectable larval odor, manipulation of river selection by invasive sea lamprey for management is viable in rivers with high encounter rates. Finally, Chapter 5 covers the implications for how altering migration routes in the sea lamprey via the application of synthesized pheromones contained in larval odor could be profitable for management.
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