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The issue of sea lice (Lepeoptheirus salmonis and Caligus clemensii) transfer from salmon farms to wild salmon is a controversial topic in British Columbia (BC). A series of sea lice epizootics (four in five years) on juvenile chum (Oncorhynchus keta) and pink (0. gorbuscha) salmon in the Broughton Archipelago (BA), an area with the highest density of salmon farms on the west coast, have caused significant concern among conservationists, local First Nations, and the general public over the possible impacts of salmon farms on wild salmon. Key to the debate has been a lack of data on ambient sea lice infection rates on juvenile salmon in the absence of the influence of salmon farms. This work represents one of the first attempts to empirically examine ambient sea lice infection rates on juvenile salmonids. Objectives were to test hypotheses including: geographic variability is a significant factor in sea lice population dynamics, ambient sea lice infection rates on juvenile salmon are low, juvenile salmon susceptibility to sea lice infection, and the influence of salmon farms on ambient sea lice infection rates. Over a three year period, samples of juvenile chum and pink salmon (n=13.874) were collected using a beach seine net in the central coast of British Columbia (Klemtu/Bella ivBella), a vast area with limited salmon farming activity. and with geography that allowed for simultaneous assessment in the same region of the natural interaction between sea lice and juvenile salmon and the influence of salmon farms on the interaction. Sampling was also conducted in other areas without salmon farms (Southern Gulf Islands: n=3847) and with salmon farms (Broughton Archipelago; n=3911). The results of the field experiments were also used in conjunction with laboratory experiments to examine the susceptibility of juvenile chum vs. pink salmon to infection by sea lice. The ambient lice infection rates for juvenile chum and pink salmon were up to 32% prevalence, less than one louse per fish and less than two lice per gram (prevalence: 2.0 (1.0) - 32.0 (19.0), mean lice per fish: 0.02 (0.01) - 0.67 (0.22), mean lice per gram: 0.56 (0.08) - 1.93 (0.13)). This result was found to be consistent across geographic areas with no salmon farming activity suggesting that geographic variability was not a significant factor in the natural interaction between sea lice and juvenile salmon. Salmon farms were found to strongly influence the relationship between sea lice and juvenile chum and pink salmon. Sea lice infection rates of juvenile salmon collected near salmon farms were significantly higher than non-salmon farming regions ranging from 3 - 150 times higher in the BA and from 2 - 14 times higher in the Klemtu region. Infection levels near salmon farms were variable in intensity from year to year. The extent to which the sea lice-salmon relationship was affected by salmon farms was dependent on farmed species, farm location, within year variability in fish size, and the scale of salmon farming activities within the region. The results from the laboratory and field studies demonstrate that juvenile chum salmon were more susceptible to infection by sea lice than juvenile pink salmon. However, the exact mechanism for the observed differences was not identified. Possible reasons for the observed differences could be related to genetically determined susceptibility, fish mucous differences, lethal lice infection tolerances. or other factors not examined. The results of this study suggest that the elevated sea lice infection rates observed in the BA and other areas present a significant risk to the health of wild salmon and that salmon farms are the most likely cause based on the biology and ecology of sea lice. In order to better understand the potential for salmon farms to affect wild salmon populations, it is suggested that investigations into farm level sea lice contributions be conducted in the BA and other areas where salmon farms operate. In addition, investigation into the lethal lice infection rates for juvenile salmon at early marine life size should also be conducted.
The issue of sea lice (Lepeoptheirus salmonis and Caligus clemensii) transfer from salmon farms to wild salmon is a controversial topic in British Columbia (BC). A series of sea lice epizootics (four in five years) on juvenile chum (Oncorhynchus keta) and pink (0. gorbuscha) salmon in the Broughton Archipelago (BA), an area with the highest density of salmon farms on the west coast, have caused significant concern among conservationists, local First Nations, and the general public over the possible impacts of salmon farms on wild salmon. Key to the debate has been a lack of data on ambient sea lice infection rates on juvenile salmon in the absence of the influence of salmon farms. This work represents one of the first attempts to empirically examine ambient sea lice infection rates on juvenile salmonids. Objectives were to test hypotheses including: geographic variability is a significant factor in sea lice population dynamics, ambient sea lice infection rates on juvenile salmon are low, juvenile salmon susceptibility to sea lice infection, and the influence of salmon farms on ambient sea lice infection rates. Over a three year period, samples of juvenile chum and pink salmon (n=13.874) were collected using a beach seine net in the central coast of British Columbia (Klemtu/Bella ivBella), a vast area with limited salmon farming activity. and with geography that allowed for simultaneous assessment in the same region of the natural interaction between sea lice and juvenile salmon and the influence of salmon farms on the interaction. Sampling was also conducted in other areas without salmon farms (Southern Gulf Islands: n=3847) and with salmon farms (Broughton Archipelago; n=3911). The results of the field experiments were also used in conjunction with laboratory experiments to examine the susceptibility of juvenile chum vs. pink salmon to infection by sea lice. The ambient lice infection rates for juvenile chum and pink salmon were up to 32% prevalence, less than one louse per fish and less than two lice per gram (prevalence: 2.0 (1.0) - 32.0 (19.0), mean lice per fish: 0.02 (0.01) - 0.67 (0.22), mean lice per gram: 0.56 (0.08) - 1.93 (0.13)). This result was found to be consistent across geographic areas with no salmon farming activity suggesting that geographic variability was not a significant factor in the natural interaction between sea lice and juvenile salmon. Salmon farms were found to strongly influence the relationship between sea lice and juvenile chum and pink salmon. Sea lice infection rates of juvenile salmon collected near salmon farms were significantly higher than non-salmon farming regions ranging from 3 - 150 times higher in the BA and from 2 - 14 times higher in the Klemtu region. Infection levels near salmon farms were variable in intensity from year to year. The extent to which the sea lice-salmon relationship was affected by salmon farms was dependent on farmed species, farm location, within year variability in fish size, and the scale of salmon farming activities within the region. The results from the laboratory and field studies demonstrate that juvenile chum salmon were more susceptible to infection by sea lice than juvenile pink salmon. However, the exact mechanism for the observed differences was not identified. Possible reasons for the observed differences could be related to genetically determined susceptibility, fish mucous differences, lethal lice infection tolerances. or other factors not examined. The results of this study suggest that the elevated sea lice infection rates observed in the BA and other areas present a significant risk to the health of wild salmon and that salmon farms are the most likely cause based on the biology and ecology of sea lice. In order to better understand the potential for salmon farms to affect wild salmon populations, it is suggested that investigations into farm level sea lice contributions be conducted in the BA and other areas where salmon farms operate. In addition, investigation into the lethal lice infection rates for juvenile salmon at early marine life size should also be conducted.
The salmon louse Lepeophtheirus salmonis is adapted to survive in hostile marine environments of the northern hemisphere, including an ability to parasitize several species of salmon. Salmonids are some of the most economically important and sought after fish for human consumption, and louse parasitism has a significant impact both on cultured and wild fish populations. Salmon Lice is a timely collection of the latest research on the cause and spread of lice infestations and management techniques being designed and implemented to combat this issue. Salmon Lice provides a thorough single volume review of Lepeophtheirus salmonis, the key parasite standing in the way of sustainable and profitable production of salmonid fishes including salmon, trout and charr. Opening with a review of the biology, morphology, life cycle, and larval behavior of the parasite, Salmon Lice proceeds to review the distribution of planktonic larvae of salmon lice, addresses management techniques used in salmonid aquaculture and capture fisheries, provides a practical assessment of the salmon lice issue and explores potential solutions to the problem. With comprehensive coverage of the biology and distribution of this harmful and ubiquitous parasite, Salmon Lice will be of value to fish health researchers, aquaculture and fisheries professionals, and seafood industry personnel to inform the management of both cultured and wild salmonid populations. Key Features: In-depth coverage of a key parasite impacting viability and sustainability of salmonid fisheries and aquaculture Integrates parasite biology and hydrodynamic models in diverse coastal ecosystems Provides a practical assessment of the salmon louse issue Reviews international salmon louse monitoring and management techniques used in salmonid fisheries and aquaculture
Pacific salmon (Oncorhynchus spp.) are key elements of ecological systems, and play an important role in the cultural foundation of human societies. All species of wild salmon face multiple, simultaneous threats, with habitat degradation likely playing a key role in survival. Open net-pen salmon farms can degrade important nursery marine habitat for wild juvenile salmon by disrupting natural salmonid host-parasite dynamics. The first two chapters in this thesis examine louse parasitism of wild juvenile chum (Oncorhynchus keta), pink (O. gorbuscha), and sockeye salmon (O. nerka) in relation to their marine migration past salmon farms. I compare sites of low and high exposure to salmon farms, and include two areas without farms on British Columbia's central and north coasts to assess baseline infection levels. Louse prevalence and abundance were lowest and most similar to natural baseline levels at low exposure sites, and highest at high exposure sites in all farm regions. A significantly greater proportion of the lice infecting juvenile chum and pink salmon were Lepeophtheirus salmonis at high exposure sites. Caligus clemensi was the principal louse species infecting all juveniles in areas without salmon farms, and at low exposure sites within salmon farm regions; C. clemensi was also the dominant louse to infect juvenile sockeye that migrated past farms. Mixed-effects modelling results showed that exposure to salmon farms was the most consistent factor to explain the variation in louse infection levels, and support my hypothesis that salmon farms are a major source of sea lice on juvenile wild salmon in regions with salmon farms. I discovered that juvenile sockeye at one particular location within the Georgia Strait hosted unusually high lice levels; this location was situated at a distance from salmon farms, but near a farm salmon processing facility. Upon further investigation, I found live sea lice, Lepeophtheirus salmonis, mucus, and fish tissue in effluent discharged from the processing facility. Sea lice transmitted from this source may pose a threat to wild salmon populations, and the release of potentially untreated offal, including blood water, is of considerable concern. These results form the third chapter in my thesis. Given the challenges facing juvenile salmon in general, and sockeye from the Fraser River in particular (i.e., 2009 was the lowest return on record), and because poor habitat conditions within Georgia Strait are considered the major cause of the recent decline in Fraser River sockeye, this raises the question as to whether food limitations are a factor. The final chapter in my thesis examines the prey assemblage, diet composition, and foraging selectivity of juvenile sockeye, and investigates whether food limitations can be detected during early migration through Georgia Strait. Juvenile sockeye demonstrated high prey diversity, with preference for particular prey. Prey were more concentrated in the north, which may help explain migratory behavior of juveniles through the study region, and temporal similarities in sockeye foraging success may reflect short-term food resource stability ...
The issue of sea lice (Lepeoptheirus salmonis and Caligus clemensii) transfer from salmon farms to wild salmon is a controversial topic in British Columbia (BC). A series of sea lice epizootics (four in five years) on juvenile chum (Oncorhynchus keta) and pink (0. gorbuscha) salmon in the Broughton Archipelago (BA), an area with the highest density of salmon farms on the west coast, have caused significant concern among conservationists, local First Nations, and the general public over the possible impacts of salmon farms on wild salmon. Key to the debate has been a lack of data on ambient sea lice infection rates on juvenile salmon in the absence of the influence of salmon farms. This work represents one of the first attempts to empirically examine ambient sea lice infection rates on juvenile salmonids. Objectives were to test hypotheses including: geographic variability is a significant factor in sea lice population dynamics, ambient sea lice infection rates on juvenile salmon are low, juvenile salmon susceptibility to sea lice infection, and the influence of salmon farms on ambient sea lice infection rates. Over a three year period, samples of juvenile chum and pink salmon (n=13.874) were collected using a beach seine net in the central coast of British Columbia (Klemtu/Bella iv Bella), a vast area with limited salmon farming activity. and with geography that allowed for simultaneous assessment in the same region of the natural interaction between sea lice and juvenile salmon and the influence of salmon farms on the interaction. Sampling was also conducted in other areas without salmon farms (Southern Gulf Islands: n=3847) and with salmon farms (Broughton Archipelago; n=3911). The results of the field experiments were also used in conjunction with laboratory experiments to examine the susceptibility of juvenile chum vs. pink salmon to infection by sea lice. The ambient lice infection rates for juvenile chum and pink salmon were up to 32% prevalence, less than one.
This book provides insights into various aspects of marine faunal communities in India, which are extremely diverse due to the geomorphologic and climatic variations along the Indian coasts. Consisting of 30 chapters by experts in their respective fields, it is divided into two parts: · Part I: Tropical Marine Faunal Communities · Part II: Ecology and Conservation Part I highlights the diversity and distribution of Foraminifera; sponges associated with seagrass; Polychaeta; Opisthobranchia; oysters; copepods; horseshoe and brachyuran crabs; echinoderms; ascidians; fishes; fish parasites; and sea mammals. Topics of Part II include the status and environmental parameters of benthos; the status of coral reefs; the invasion of snowflake coral; the recovery of bleached corals; the socioeconomics and management of dugong; marine biodiversity conservation and management in India; the assessment of the marine fauna of the Indian Wildlife Protection Act; and marine biodiversity protected areas in India. This book will serve as a valuable reference work for marine scientists, as well as for environmental managers and policy makers.
Whether through loss of habitat or cascading community effects, diseases can shape the very nature of the marine environment. Despite their significant impacts, studies of marine diseases have tended to lag behind their terrestrial equivalents, particularly with regards to their ecological effects. However, in recent decades global research focused on marine disease ecology has expanded at an accelerating rate. This is due in part to increases in disease emergence across many taxa, but can also be attributed to a broader realization that the parasites responsible for disease are themselves important members of marine communities. Understanding their ecological relationships with the environment and their hosts is critical to understanding, conserving, and managing natural and exploited populations, communities, and ecosystems. Courses on marine disease ecology are now starting to emerge and this first textbook in the field will be ideally placed to serve them. Marine Disease Ecology is suitable for graduate students and researchers in the fields of marine disease ecology, aquaculture, fisheries, veterinary science, evolution and conservation. It will also be of relevance and use to a broader interdisciplinary audience of government agencies, NGOs, and marine resource managers.
Sea lice are serious pests of commercially farmed fish and this book provides the first detailed overview of their biology and existing methods of control. It deals comprehensively with both the pure and applied aspects of sea lice biology and covers a wide range of topics to make it invaluable to practitioners and researchers alike.