DEVELOPING CULTURE METHODS FOR LARVAL PACIFIC LAMPREY: ENERGETIC DEMANDS

As a First Food for the Confederated Tribes of the Umatilla Indian Reservation , Pacific lamprey holds a deep cultural significance . Artificial propagation is a tribal restoration focus, both to replenish declining wild populations and gain a greater understanding of this species.

In culture, oxygen availability can be limiting , especially  after larvae are fed oxygen-consuming yeast and fish food. Therefore, it is crucial to understand oxygen consumption rates of the two age classes in culture (2018 and 2019 spawn), and in conditions with or without food. A goal for artificial propagation is release into the wild, so it is vital to understand how  energy demands and fitness of propagated larvae compare to wild-caught larvae.

Oxygen consumption was measur ed in static chambers with optical oxygen probes. The resulting data was compared between age classes, between fed and unfed groups , and between lab-propagated and wild-caught larvae. We hypothesized that oxygen uptake would increase with size and with feeding due to specific dynamic action and yeast consumption and would drop back down after feeding. We also hypothesized that  the  energy demands of wild lamprey and lab-propagated lamprey would mirror each other.

Larvae from the 2019 spawn have low respiration rates. However, upon feeding the combination of yeast respiration and  mostly specific dynamic action of the lamprey significantly increases oxygen consumption.  Larvae return to their normal consumption rate  in 24 hours .  Larvae  from the 2018 spawn  had higher weight-adjusted respiration rates even before feeding (Fig. 1) .  This shows that oxygen is vital when feeding. Wild and lab propagated lamprey had similar oxygen demands (Fig 2). This indicates that lab-reared lamprey may be adequate  surrogates for wild fish.