Optimizing early weaning protocols for Burbot larvae Matuha, Moureen; Oliver, Luke P.; Bruce, Timothy J. ...
North American journal of aquaculture,
January 2024, 2024-01-00, Letnik:
86, Številka:
1
Journal Article
Recenzirano
Objective
This study aimed to minimize live prey usage and duration in Burbot Lota lota larval culture. Specifically, two trials were conducted to assess the viability of EZ Artemia (liquid Artemia ...replacement) and Gemma microparticulate diets as alternatives to traditional live feeds, investigating their impact on larval Burbot's growth and survival.
Methods
In trial 1, five treatments were evaluated: the control group received rotifers (Brachionus plicatilis) and Artemia spp. from 11 to 50 days posthatch (dph). Treatment (Trt) 1 had live feeds from 11 to 78 dph; Trt 2 received only microparticulate diets; Trt 3 was fed rotifers at 11–22 dph and Gemma microparticulate diets at 21–50 dph; and Trt 4 received rotifers at 11–20 dph, then co‐feeding of Artemia spp. and EZ Artemia at 21–32 dph, followed by EZ Artemia at 33–40 dph. In trial 2, five feeding treatments were assessed: the control group was the same as in trial 1; Trt 1 received rotifers at 11–25 dph and EZ Artemia at 20–50 dph; Trt 2 had Artemia spp. from 11 to 30 dph and EZ Artemia at 25–50 dph; Trt 3 received only EZ Artemia; Trt 4 had Artemia spp. at 11–21 dph, followed by co‐feeding of Artemia spp. and Gemma Wean at 22–32 dph and exclusive feeding of Gemma Wean from 33 to 78 dph.
Result
In trial 1, it was found that the utilization of EZ Artemia reduced the live feeding period by 17 days; however, both survival and growth were notably lower compared to the control. In trial 2, survival rates varied from 0% to 30.94%, with Trt 1, Trt 2, and Trt 4 demonstrating a reduction in the live feeding period by 17–24 days. Survival rates for the Trt 1 and Trt 2 groups did not exhibit a significant difference from the control group.
Conclusion
These studies collectively show that eliminating rotifers or Artemia spp. during Burbot larval culture can be accomplished with minimal adverse effects on both survival and growth.
Impact statement
The production of traditional live feeds (rotifers and Artemia spp.) entails significant expenses and labor. Early weaning of Burbot larvae onto non‐live foods can reduce infrastructure costs, offering flexibility in feeding practices. This study showcases the effectiveness of prepared feeds including (EZ Artemia and Gemma microparticulate diets) in diminishing reliance on live feeds, presenting them as viable alternatives to rotifers or Artemia spp. in Burbot larval production. This approach enhances the economic viability of commercial hatchery operations for producers interested in culturing this new emerging freshwater species.
Burbot (Lota lota) are an ideal candidate for cool or cold-water aquaculture and are gaining interest because of their high economic value, low temperature requirements, and fast growth rate. Limited ...information exists on the innate and adaptive immune systems of this species. This is partly due to the lack of species-specific tools to determine antibody responses following disease or vaccination or to characterize the immune response in general. An anti-IgM monoclonal antibody (mAb 27C) was developed and characterized via enzyme-linked immunosorbent assay (ELISA) and Western blot for species specificity, affinity to the heavy chain of burbot IgM, and cross-reactivity to other reagents used in the analysis. The 27C monoclonal antibody was further utilized to develop an ELISA protocol to measure the specific antibody response of burbot following exposure to two pathogenic strains of Aeromonas sp. (A141 and IR004). This ELISA confirmed that vaccinated burbot that survived the challenge with either strain developed statistically higher titers of anti-Aeromonas antibodies specific for the relative strain when compared to fish that were not vaccinated or challenged. Western blot analysis further demonstrated that burbot surviving challenge had serum IgM that recognized distinct antigens specific to the strain they were challenged with, A141 bound to antigens in the 50-250Kda range and IR004 bound to a distinct 150Kda antigen. Western blots further indicated that each strain shared antigenic regions regardless of experimental Aeromonas strain exposure. Finally, immunofluorescent staining confirmed that mAb 27C binds to membrane-bound IgM (presumably B cells) on burbot head kidney cells. Taken together, results from this study demonstrate that mAb 27C specifically recognized burbot IgM and will be an important tool to further characterize the adaptive and cellular immune responses of this fish species.
Display omitted
•Production of a monoclonal antibody (mAb27C), specific to the heavy chain of burbot IgM.•mAb 27C detects differences in Aeromonas sp. (strains A141 and IR004) antibody titers after exposure or vaccination.•mAb 27C detects immunogenic regions of Aeromonas sp. (strains A141 and IR004) via western blot.•mAb 27C detects IgM + cells via immunocytochemistry.
In this study the comparison of spontaneous and hormone-induced reproduction of burbot under controlled conditions was made. During the first two years of the study, burbot spawned spontaneously and ...artificially after hormonal treatment. The application of sGnRHa resulted in a 100% ovulation rate within 4 to 5days. Over the 20days of the experiment, in both years, 65% of females (13 from 20) spawned spontaneously. The biological quality of eggs, expressed as a percentage of live embryos (58.6–60.3%), was generally lower than in only hormone-induced spawned groups (84.2–89.2%). The embryo survival in groups spawned spontaneously decreased in time during the spawning season. Hormonal stimulation of non-ovulated females caused 43–57% of ovulation but with low embryo survival rates (34.2–44.2%). In the third year of the study, 55% of females ovulated spontaneously during the first 10days of the experiment. Stimulation of non-ovulated females resulted in final oocyte maturation and ovulation in 78% of females. The embryo survival rate was higher (63.2%) than in fish stimulated hormonally after 20days of spontaneous spawning (but not after 10days). The application of hormonal treatment in burbot reproduction under controlled conditions shortened latency time, synchronized final oocyte maturation and resulted in high embryo survival rate.
•Burbot can be reproduced spontaneously under controlled conditions.•The application of hormonal stimulation (sGnRHa) resulted in synchronized burbot spawning.•Females which do not spawn spontaneously might reproduce artificially.
Abstract
Objective
The Northern Refuge of Lake Michigan was established under the auspices of the Great Lakes Fishery Commission in 1985 as an additional step toward restoring a self‐sustaining Lake ...Trout
Salvelinus namaycush
population to the lake. The overall goal of our study was to assess progress toward Lake Trout rehabilitation in the Northern Refuge through 2021.
Methods
We conducted annual (1992–2021) gill‐net surveys in the fall to assess the adult population and beam trawl surveys in the spring to assess naturally reproduced age‐0 Lake Trout.
Result
Spawner abundance averaged 45 fish • 305 m of gill net
−1
• day
−1
during 1992–1999, just 4 fish • 305 m of gill net
−1
• day
−1
during 2000–2014, and then 67 fish • 305 m of gill net
−1
• day
−1
during 2018–2021. Sea Lamprey
Petromyzon marinus
wounding rate decreased by nearly 90% between the 2000–2014 and 2015–2021 periods. The average annual mortality rate of adult Lake Trout decreased from 43% during the 1990s and 2000s to 22% during 2015–2021. All of these population dynamics were partly driven by changes in Lake Trout stocking rates, which declined by roughly 50% during 1994–1996 but then increased roughly twofold during 2006–2010 and remained at this higher level during 2010–2018. In 2021, early signs of natural recruitment of Lake Trout became evident. Beam trawling during June 2021 yielded a wild age‐0 Lake Trout, the first ever caught since the surveys began in 1992. In addition, 15 (4% of total catch) of the Lake Trout caught in the fall 2021 gill‐net survey were unclipped (wild) fish. Estimated ages of these wild fish indicated that natural recruitment had begun sometime around 2015.
Conclusion
With Alewife
Alosa pseudoharengus
abundance in Lake Michigan at record low levels, Sea Lamprey wounding rate greatly reduced, and Lake Trout spawner abundance at relatively high levels, the outlook for Lake Trout rehabilitation in the Northern Refuge holds promise.
Impact statement
We documented significant progress toward the goal of establishing a self‐sustaining Lake Trout population in the Northern Refuge of Lake Michigan during 2009–2021. Accomplishing this goal is a key step in stabilizing the ecosystem, but additional effort is still needed to reach the goal.
Burbot (Lota lota) stomach content was analyzed from eastern Lake Michigan using 835 stomach samples collected from 1996 to 2012. Our results show alteration in the prey community consumed between ...the early study period (1996–2006) and the more recent period (2007–2012). In the early years, alewives (Alosa pseudoharengus), slimy sculpin (Cottus cognatus), and mottled sculpin (C. bairdii) were the most important prey items, with regional variation suggesting greater use of Cottus spp. in the southern lake sites compared to northern sites where alewives were predominant. Non-native round gobies (Neogobius melanostomus) replaced Cottus spp. and alewives as the most frequently found prey item in the more recent years in the dataset, and other minor constituents of the prey assemblage nearly disappeared from the stomach samples. Round gobies first appeared in the diet in 1999 and became frequent by 2006, reaching 55.80% (±5.36) in 2012. The dominance of round goby as prey for burbot is important for the transfer of benthic nutrients into the upper food web in Lake Michigan. Our data highlight the striking food web shift linked to the non-native species invasion that has taken place in Lake Michigan since 2000 and emphasize its impact on native predator ecology.
Burbot Lota lota are distributed across the Laurentian Great Lakes where they occupy a top piscivore role. The St. Clair-Detroit River System is known to provide a migration corridor as well as ...spawning and nursery habitat for many indigenous fishes of economic and ecological significance. However, knowledge is scant of the early life history of burbot and the importance of this system in their dispersal, survival, and recruitment. In order to assess the role of the St. Clair-Detroit River System to burbot ecology, we collected larval burbot during ichthyoplankton surveys in this system from 2010 to 2013 as part of a habitat restoration monitoring program. More and larger burbot larvae were found in the St. Clair River than in the lower Detroit River, although this may be due to differences in sampling methods between the two rivers. Consistent with existing studies, larval burbot exhibited ontogenesis with a distinct transition from a pelagic zooplankton-based diet to a benthic macroinvertebrate-based diet. Our results demonstrate that the St. Clair-Detroit Rivers provide food resources, required habitat, and a migration conduit between the upper and lower Great Lakes, but the contribution of these fish to the lower lakes requires further examination.
Experiments were conducted to optimize triploid induction parameters, and assess triploid sterility, in burbot. Duration and timing of shocks were based on degree minutes, temperature multiplied by ...time, denoted as °C min. Hydrostatic shock experiments investigated the duration of shock using 7500 or 8500 psi at 180°C min post‐fertilization. Thermal shocks investigated duration of shock and post‐fertilization shock timing using a shock of 16°C. Sterility experiments investigated egg survival when diploids were crossed with triploids. Hydrostatic shock of 7500 psi for 10 or 20°C min can induce triploidy ≥90% and exhibits survival that is statistically similar, p ≤ 0.05, to controls. Hydrostatic shock of 8500 psi for 5 or 10°C min yielded triploid induction of 93% and 100%, respectively, with survival that is statistically similar to controls, p ≤ 0.05. Thermal induction experiments indicated shocks at 120°C min post‐fertilization, for durations between 350 and 450°C min, have potential to induce triploidy ≥90% while facilitating survival statistically similar to controls, p ≤ 0.05. Induction of tetraploidy was observed. Sterility experiments determined that triploid burbot are functionally sterile. These results may allow production of burbot where sterility is required.
The diet of adult burbot (Lota lota) collected from two locations in the Mackenzie Delta during the winter was characterized using stomach content and stable isotopes analysis (δ ¹³C and δ ¹⁵N). ...Burbot consumed mainly ninespine stickleback, juvenile northern pike, and conspecifics, with high δ ¹⁵N confirming long-term piscivory. Of the 66 adult burbot sampled, 530 juvenile burbot were enumerated from their stomachs, and from these, 50 juvenile burbot were counted. Many of these juveniles were undigested and were examined for diet content and stable isotopes. Juveniles primarily consumed invertebrates, however, piscivory was detected in young-of-the-year, with stickleback and conspecifics becoming more important as size increased, possibly resulting in competition with adults for small-size fish. δ ¹⁵N indicated juvenile burbot occupied a lower tropic level while δ ¹³C suggested differences in habitat properties between sites. Cannibalism was important to adult diet where the highest frequency of occurrence was 96%, with conspecifics accounting for 82 and 93% of diet items by number and weight, respectively. Cannibalism in burbot increased its trophic breadth and juvenile growth rate, and combined with the amount of conspecifics consumed possibly promoted population stability and coexistence with intraguild predators.
Burbot Lota lota maculosa numbers in Kootenay Lake and Kootenai River of British Columbia, Idaho, and Montana have diminished due to habitat changes from the construction of Libby Dam. Recent ...implementation of a conservation strategy included aquaculture to supplement the population using a donor stock from a self-sustaining lake population within the watershed. Evaluation of release strategies using telemetry and mark recapture through hoop netting suggests lake-origin Burbot have adapted to the Kootenai system and selected riverine over lacustrine habitat. Previous telemetry work identified good survival and dispersal of released Burbot, and vast dispersal distance and lacustrine use. However, our analysis of a broader telemetry dataset indicated that only 24% of age 1–4 Burbot were detected in the lake. Recapture hoop net data indicated that Burbot residing in the river have growth and survival rates comparable to the historical population. Spawning of hatchery origin fish was detected at historical riverine spawning locations. Other than later spawn timing, our evaluations suggest lake-origin fish are mimicking movement and habitat use of the historical riverine population. This study, in combination with others, provides evidence that Burbot progeny from lacustrine brood stock can successfully survive, grow, disperse, and spawn in a riverine environment.
