The objective of this study was to determine the effect of temperature on growth and survival of larval and juvenile burbot, Lota lota maculosa. Burbot aquaculture is developing primarily in response to declining wild stocks and a need to restore such populations. Beyond conservation efforts, there is also potential to culture this species commercially. However, many important aspects of burbot culture remain unaddressed. In this study larval and juvenile burbot were reared at three constant water temperatures (10, 15, and 20°C) in an intensive culture setting. Two 30 day trials were conducted during the larval life stage and one 60 day trial during the juvenile life stage. In Trial 1, larval burbot (mean total length ± SD, 6.9 ± 1.0 mm, approximately 65 days post hatch) reared at 20°C grew the fastest, while growth was lowest in the 10°C treatment. Survival was inversely related to temperature, with the lowest average of 6.6% observed in larvae reared at 20°C. The percentage cannibalized was quantified and found to be positively correlated with water temperature, and reached 58.0% in larvae reared at 20°C. In Trial 2, as larvae approached metamorphosis (12.9 ± 1.9 mm, approximately 100 days post hatch), growth was also highest in fish at 20°C and lowest in those at 10°C. At this stage survival was higher in fish at lower temperatures, but the percentage cannibalized appeared independent of temperature, averaging over 50% in fish at all temperatures. In Trial 3, growth of juveniles (59.9 ± 12.4 mm, approximately 205 days post hatch) reared at 15 and 20°C was not significantly different, yet both displayed significantly increased growth relative to juveniles reared at 10°C. Juveniles were fully transitioned to a dry diet, and survival averaged > 93% in all culture temperatures. The percentage cannibalized during this life stage averaged b 5%, and was not affected by temperature. This study demonstrated the importance of water temperature, as it clearly affects culture performance of larval and juvenile burbot. Results from this study have implications for maximizing growth during larval and juvenile life stages of this species, and provide a comparative, empirical framework for establishing conservation, or commercial aquaculture programs for burbot.

The Pacific lamprey Entosphenus tridentatus is an ancestral species of critical importance to the ecosystem and indigenous cultures in the Pacific Northwest. Conservation aquaculture has been proposed as a potential technique to restore Pacific lamprey populations. Intensive culture methods and diets for this species have not been developed. A sixteen week feeding trial tested the effects of seven diet treatments on the survival, growth, fatty acid profile and whole body lipid content of Pacific lamprey ammocoetes. Dietary treatments were: active dry yeast, yeast plus fish oil emulsion, micro‐algae, micro‐algae plus fish oil emulsion, yeast with micro‐algae, yeast with micro‐algae plus fish oil emulsion and yeast with larval fish diet. Each diet was offered to five replicate tanks stocked with 20 ammocoetes that were 51 days post hatch. Survival during the trial was not affected by diet. The greatest length and weight increases were in fish fed diets containing yeast. Growth decreased as the amount of algae in the diet was increased. Lipid retention was significantly higher in fish fed yeast with larval fish diet relative to the other treatments. Feed conversion ratio was lowest in fish fed diets containing yeast. Whole body fatty acid profiles tended to reflect the fatty acid profile of the diet. Percentages of 20:5n‐3 and 22:6n‐3 were significantly higher in fish fed diets containing fish oil emulsion. Overall, yeast with larval fish diet provided the best growth performance in larval Pacific lamprey.

The Lost River Sucker Deltistes luxatus is endemic to the Klamath Basin in southern Oregon and northernCalifornia. Population declines led to listing this species as endangered in 1988. Its native habitat has been greatly reduced and degraded putting their future in question. If this species is to be reared in captivity to prevent extinction, the development of culture methodologies is necessary. Successful initial feeding methods are one of the first areas of culture that need to be developed. Lost River Suckers begin feeding during the larval life stage. Larval fish often require live prey at the onset of feeding; however, it may be possible to start larvae on formulated microdiets. We investigated the use of live Artemia and two commercial microdiets (Hikari and Otohime brands) as first feeds over the course of a 41-d feeding trial. Starting on day 21 of the trial, feed sizes were increased, and the Artemia-fed fish were offered a commercial microdiet (Otohime) while being co-fed Artemia through day 26 of the trial (6 d cofeeding). After day 26 the Artemia-fed fish were only offered the microdiet. The response variables of total length, weight, survival, whole-body lipid content, and whole-body fatty acid profile were measured during and at termination of the trial. Fish grew significantly faster when started on Artemia and also displayed significantly higher survival compared with fish fed only commercial microdiets. Fish started on Artemia transitioned well to Otohime B1, and maintained 95.2% (SD, 2.2) survival over the 41-d feeding trial. The fatty acid profiles of the fish generally reflected the profiles of the diets they were fed. This study demonstrated that live Artemia followed by a transition to Otohime commercial feed is an effective feeding regimen for the duration of the larval phase of this species.

SummaryFeeding burbot Lota lota maculosa larvae were released in pens deployed in two ponds of the Kootenai River, Idaho, USA drainage: one pond each in 2008 through 2010. The objectives were to compare results of survival, growth, and the practicality of pen rearing burbot. In 2008 we stocked two pens at low density with 30 burbot larvae each (20 larvae per m 3 ) and collected a total of 47 of the 60 after about 70 days, for an estimated average pen survival of 78%. Average length in August 2008 was 48 mm total length. Yellow perch Perca flavescens were discovered in the pond. The pond was drained in December of 2008 to eradicate the yellow perch. In 2009 a total of 467 feeding burbot larvae were placed between five pens at three densities of about 18, 39, 95 burbot larvae per m 3 . By September, average TL of burbot was 49 mm. Growth appeared to slow for all stocking densities after the fifth week. Average survival for burbot from initial pen stocking to final recovery was 18%. Best survival was at the two lower densities. In 2010 stocking was moved to a second pond and a total of 484 feeding burbot larvae were placed between five pens at the three densities. In 2010 burbot were supplementally fed. Average survival for the low, moderate, and high density pens was 86, 78, and 20%, respectively. Mean TL at collection in 2010 for the low, moderate and high densities were 37, 37, and 40 mm, respectively. Food availability was believed to be a limiting factor to survival because adding zooplankton appeared to improve survival.