Document: KAR-3-51-16

Long-distance fish migration: More than a matter of getting from here to there.

LIMBURG, K.E.*

SUNY, Syracuse, NY 13210 USA ¹

Abstract:
Long-distance fish migration is a spectacular example of the ontogenetic niche shift. Our general perception of these migrations tends toward overly simplistic descriptions, due in part to the impracticality of direct observation, and to the imperfect information derived from tagging studies. I discuss here how relatively new techniques, which exploit the microchemical properties of otoliths (fish earstones), provide detailed information on individual migrating fish. In particular, I show how strontium incorporated into otoliths can serve as a proxy for salinity; how it can be used to study the movements of diadromous fishes (fresh water Sr:Ca range 0.5-1.5; marine waters, Sr:Ca range 3-6); and how this provides a much more complex picture of migration. For example, European freshwater eels engage in a wide repertoire of movements, often moving between marine and brackish waters without entering fresh water (65% of the time in an ongoing study). Blueback herring in the Hudson/Mohawk drainage not only show classic anadromous patterns, but also a new behavior due to presence of canals and locks: occasional to complete freshwater residency. These empirical observations place a new demand on ecological theory to explain the rich repertoires of large-scale habitat switching increasingly revealed by natural chemical tracers.

Keywords: fish migration, otolith microchemistry

This abstract is being presented at: 8:00 AM in session:
Oral Session #57: Ocean-Going Fish and Mammals.