Ammocoetes of Pacific Lamprey Are Not Susceptible to Common Fish Rhabdoviruses of the U.S. Pacific Northwest

Journal of Fish and Wildlife Management

Silver

et al. 2017

Native lamprey populations are declining worldwide. In the Pacific Northwest focus on conservation and management of these ecologically and culturally important species has increased. Concern has emerged regarding the effects of sampling and handling of lamprey, with little to no attention given to the larval lifestage. We monitored the survival of larval Pacific Lamprey Entosphenus tridentatus and Lampetra spp. after backpack electrofishing, deepwater electrofishing and suction-pumping, anesthesia, and handling. We performed survival trials on wild-caught lamprey (n = 15 larvae in each trial) collected from the Clackamas River drainage in Oregon, USA, coupled with control group trials from lamprey sourced from a hatchery (n = 10 larvae). Short-term (96 h) survival was >98% with only one observed mortality. Delayed mortality (1 wk) was observed for four individuals that had fungus; two of those were positive for the bacteria Aeromonas hyrdrophila. We recorded blood hematocrit as a secondary measure of stress. The baseline, nonstressed larvae hematocrit levels did not differ from those of fish that had undergone stress through electrofishing, suction-pumping, and handling without anesthesia. Electrofishing, suction-pumping, and anesthesia showed no short-term negative effects on larval lamprey although potential long-term effects remain unstudied. These techniques appear to provide efficient and relatively safe methods for collecting and surveying larval lamprey.

Section: Introductionmentioning

confidence: 99%

Low Mortality of Larval Lampreys from Electrofishing, Suction-pumping, Anesthesia, and Handling

Journal of Fish and Wildlife Management

Silver

et al. 2017

“…The unique life history of the Pacific Lamprey poses challenges to captive rearing that are uncommon in traditional teleost culture. Although larval Pacific Lampreys have been successfully held for experimentation (Silver et al 2009;Kurath et al 2013) and have metamorphosed in captivity (McGree et al 2008), explicit information on appropriate holding configurations, rearing habitats or substrates, and food types and quantities needed for growth of robust individuals in captivity is not available. Thus, methods need to be developed for the maintenance and growth of lamprey larvae reared in captivity.…”

mentioning

confidence: 99%

Feeding and Growth of Larval Pacific Lamprey Reared in Captivity

Silver

et al. 2015

N American J Aquac

Pacific Lampreys Entosphenus tridentatus are declining in the Columbia River basin as well as in much of their broader range. To mitigate for reductions in abundance, strategies such as hatchery propagation and captive rearing of lamprey larvae are currently being considered. We conducted a series of experiments using captive larval Pacific Lampreys at Eagle Creek National Fish Hatchery to investigate the effect of different food types and different food concentrations on the growth of larvae. In our first experiment, we evaluated the growth of larvae (TL range, 59–145 mm) given four different food types (algae, leaves, yeast–larval fish food, and salmon carcass analogs) and a control group that was not fed. Assimilation of food types was evaluated by tracking unique stable isotope signatures of δ13C and δ15N within larval tissues. Results from experiment 1 indicated that lampreys fed a diet of salmon carcass analog or algae had positive growth (up to 0.16 mm/d and 42% proportional change in length) over approximately 6 months. Isotopic analyses of larval tissues showed unique signatures that matched those of their specific food treatment. Based on the results of experiment 1, we conducted a second experiment to evaluate the growth of larvae fed four different quantities of salmon carcass analog. Results from this experiment indicated larval growth rate increased with increasing rations of food, but positive growth was observed in all feeding treatments. The highest dose of salmon carcass analog resulted in the highest growth (up to 0.15 mm/d and 36% proportional change in length) over 6 months. We successfully reared larval Pacific Lampreys in captivity with minimal mortality and positive growth, which highlights the potential to use captive rearing and propagation as a conservation tool for this ecologically and culturally important species.

“…It is not known if these adult lampreys were infected with Aeromonas spp., so treatment efficacy is unknown. Explicit bacterial host challenge and disinfection experiments similar to those conducted by Kurath et al (2013) with rhabdoviruses of the Pacific Northwest will need to be conducted to determine the efficacy of any A. salmonicida treatment program.…”

Section: Discussionmentioning

confidence: 99%

“…Previous research on viral pathogens of Pacific Lamprey is scant. Kurath et al (2013) showed that larval Pacific Lamprey were not susceptible to common rhabdoviruses of the Pacific Northwest. Only opportunistic findings exist for bacterial pathogens of diseased adult Pacific Lamprey.…”

Section: Introductionmentioning

confidence: 99%

Pathogens of Pacific Lamprey Detected Through Routine Fish Health Screenings

Journal of Fish and Wildlife Management

Lujan

2019

Interest in conservation, management, and captive rearing of Pacific Lamprey Entosphenus tridentatus in the Pacific Northwest has risen in recent years. General and specific information regarding the occurrence of fish pathogens and the risk of Pacific Lamprey as a vector for pathogens to other species is not well understood. Specific efforts to captively rear or artificially propagate Pacific Lamprey at facilities that are used for Pacific salmon Oncorhynchus spp. have increased. We performed fish health surveys on wild-caught larval and adult Pacific Lamprey from locations that were used as lamprey sources for captive research to determine the occurrence of bacteria, viruses, and parasites that may be pathogens. A variety of potential pathogens was detected, most notably Aeromonas hydrophila and Vibrio vulnificus from larval Pacific Lamprey and A. salmonicida from adult lampreys. There was a general lack of pathogenic activity and absence of viral detections from all lampreys. The diversity of bacteria encountered from the larvae in our study could be indicative of the wide diversity of bacteria that is known to be associated with larval lamprey in general. Further efforts to understand pathogenic risk from Pacific Lamprey to salmonid propagation programs are warranted.