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USGS2024

Evaluating behavioral responses of spawning-phase Walleyes to odors of rivers and other Walleyes

Many fish species show a remarkable ability to home to streams for spawning and fishery managers have applied that knowledge to restore or rehabilitate populations of some species. Walleye Sander vitreus show strong homing tendencies and the ability to select their natal river from other streams. The role of olfactory cues has been hypothesized but never tested in Walleye and many aspects of Walleye migratory behavior associated with spawning are poorly understood. The objectives of our study were: 1) to determine if spawning-phase Walleye from the Ford River in Michigan favored the odor of water from their home stream over that of a nearby river, and 2) to examine effects of male and female Walleye (conspecific) odors on water choice preferences of spawning-phase male Walleyes to learn whether such odors may attract adult Walleyes into rivers. Flow-through flume assays with two side-by-side channels were used to evaluate behavioral preferences of spawning-phase Walleye to river and conspecific odors. Odors of Ford River in 2021 trials and conspecific males in 2019 trials (when analyzed by individuals but not groups) influenced the behavior of male Walleye. However, follow up work during 2022 did not detect any responses to Ford River water or male-conditioned water. Additional work is needed to determine the possible role of olfactory cues in the homing behavior of spawning-phase Walleye.

Michigan↗

USGS2014

A new clarification method to visualize biliary degeneration during liver metamorphosis in sea lamprey ( Petromyzon marinus )

Biliary atresia is a rare disease of infancy, with an estimated 1 in 15,000 frequency in the southeast United States, but more common in East Asian countries, with a reported frequency of 1 in 5,000 in Taiwan. Although much is known about the management of biliary atresia, its pathogenesis is still elusive. The sea lamprey ( Petromyzon marinus ) provides a unique opportunity to examine the mechanism and progression of biliary degeneration. Sea lamprey develop through three distinct life stages: larval, parasitic, and adult. During the transition from larvae to parasitic juvenile, sea lamprey undergo metamorphosis with dramatic reorganization and remodeling in external morphology and internal organs. In the liver, the entire biliary system is lost, including the gall bladder and the biliary tree. A newly-developed method called “CLARITY” was modified to clarify the entire liver and the junction with the intestine in metamorphic sea lamprey. The process of biliary degeneration was visualized and discerned during sea lamprey metamorphosis by using laser scanning confocal microscopy. This method provides a powerful tool to study biliary atresia in a unique animal model.

Journal of Visualized Experiments↗