Lamprey surveys

Until recently, surveying for lamprey ammocoetes (larvae) has generally required expensive and sometimes hazardous electrofishing equipment. Our biologists have adapted methods from a European study published in Fisheries Research, “A new sampling technique for larval lamprey population assessment in small river catchments” by Lasne et al., and were able to reproduce the study’s success in quantifying ammocoetes with a Hess sampler.

The study mentioned above found that when the same sites were surveyed using a Hess sampler and electrofishing, the amount of ammocoetes detected was greater when using the Hess sampler. They outline several notable issues with electrofishing for ammocoetes, including dysfunction of electrofishing equipment in turbid waters (i.e. conditions that are easily caused in ammocoete habitat due to their proclivity toward fine substrate). Electrofishing also requires a user to visually observe the reactions of fish to electrical currents and react to them accordingly by decreasing their strength if fish are distressed (and increase them if they are unresponsive to the currents). For ammocoetes this can be difficult or impossible because they spend their lives burrowed in the sediment on the bottom of a water body. It is likely that using a Hess sampler is not only a more efficient method of quantifying ammocoetes, but also more humane. Additionally, our use of a lamprey Photarium designed by Yakama Nation Fisheries lamprey biologists and Wild Fish Conservancy Northwest minimizes or eliminates time that lampreys are out of the water while measurements and other data are being collected, reducing stress on the fish.

Constructing the Hess sampler in question costs less than $50, and the equipment is user-friendly. As such it is significantly more accessible to researchers and groups seeking to study lampreys. It is our hope that this will lead to a greater understanding of lamprey population dynamics and ecology in the Northwest. Resources on the Pacific lamprey species including the Pacific lamprey (Entosphenus tridentatus), Pacific brook lamprey (Lampetra pacifica), and western brook lamprey (L. richardsonii) can be found through the Pacific Lamprey Conservation Initiative at pacificlamprey.org.

Our lamprey services:

-Workshops and field practicums on lamprey surveys, identification and ecology

-Lamprey surveys (redd/spawning ground, ammocoete)

-Population structure determination and analysis