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On the decline of Pacific salmon and speculative links to salmon farming in British Columbia
Abstract
Pacific salmon abundance along the West Coast of Canada has been in sharp decline since the early 1990s. Declines have been most severe for coho and chinook salmon despite large additions of hatchery-reared fry and smolts. There is particular concern for populations of wild coho because, in addition to low abundance, up to 80% of the juvenile coho in the coastal waters has been identified as being produced by enhancement projects. The most likely reasons for the decline in Pacific salmon stocks include a combination of climate change, overfishing, and freshwater habitat destruction. There have also been suggestions that salmon farming in British Columbia has contributed to the decline of salmon stocks. The hypothesized effects of salmon farming include potential ecological interactions as well as disease concerns. In this paper, we consider the effects of climate change on the abundance of wild salmon stocks as well as potential genetic, ecological, and disease concerns. Shifts in climate in 1977 and 1989 resulted in significant changes in production for a number of marine fish species including Pacific salmon. These climate-related changes, combined with local overfishing and the loss of freshwater habitat, have left some salmon stocks at very low levels. Large-scale salmon enhancement projects have also resulted in significant ecological and genetic interactions with wild salmon, particularly for coho and chinook stocks. These interactions have tended to reduce genetic diversity and result in the replacement of wild salmon by hatchery fish. Hatcheries also represent a potential source of disease pathogens although the magnitude of the problem is difficult to quantify because the disease agents of concern are widespread in both wild and hatchery Pacific salmon as well as a number of non-salmonid hosts. In addition, the same antibiotics used in the salmon farming industry are also used in salmon enhancement projects, making it difficult to identify the source of some pathogens. Although farmed salmon are also a potential source for these disease pathogens, surveys of pathogens in wild and hatchery fish show no patterns that could be attributed to salmon farming. Recent improvements in fish husbandry, including the development and widespread use of vaccines, have also reduced the risk of disease transfer from farmed fish to wild or hatchery fish. The combined evidence indicates that salmon farming, as currently practiced in British Columbia, poses a low risk to wild salmon stocks particularly when compared to other potential factors.
... Salmon are typically farmed in areas frequented by wild salmon, and thus, algal toxins also represent a potential threat to wild salmon. Salmon are an integral part of the trophic food web, including a food source for endangered and threatened resident orcas [2]; thus, algal toxins, to which they are exposed, may have far reaching impacts on the ecosystem's health. ...
... As wild salmon and other marine animals are present in the same waters, algal toxins may be responsible for morbidity and mortality in these organisms. Importantly for conservation managers, some wild salmon populations have been in decline (Noakes et al., 2000). That the presence of these toxins could be a contributing factor merits further investigation. ...
Harmful algal blooms (HABs) in coastal British Columbia (BC), Canada, negatively impact the salmon aquaculture industry. One disease of interest to salmon aquaculture is Net Pen Liver Disease (NPLD), which induces severe liver damage and is believed to be caused by the exposure to microcystins (MCs). To address the lack of information about algal toxins in BC marine environments and the risk they pose, this study investigated the presence of MCs and other toxins at aquaculture sites. Sampling was carried out using discrete water samples and Solid Phase Adsorption Toxin Tracking (SPATT) samplers from 2017–2019. All 283 SPATT samples and all 81 water samples tested positive for MCs. Testing for okadaic acid (OA) and domoic acid (DA) occurred in 66 and 43 samples, respectively, and all samples were positive for the toxin tested. Testing for dinophysistoxin-1 (DTX-1) (20 samples), pectenotoxin-2 (PTX-2) (20 samples), and yessotoxin (YTX) (17 samples) revealed that all samples were positive for the tested toxins. This study revealed the presence of multiple co-occurring toxins in BC’s coastal waters and the levels detected in this study were below the regulatory limits for health and recreational use. This study expands our limited knowledge of algal toxins in coastal BC and shows that further studies are needed to understand the risks they pose to marine fisheries and ecosystems.
... North American aquaculture is currently dominated by Atlantic salmon, resulting in production of this species on both the East and West coasts of Canada. However, because Atlantic salmon are not indigenous to the West coast, there is public concern regarding the introduction of foreign diseases to wild populations as well as the exposure of native salmon species to ecological niche competition through farmed escapees (reviewed by Noakes et al., 2000). Despite the negative publicity associated with farming Atlantic salmon on the West coast, a staggering 71% of Canadian salmon production occurs in British Columbia (Statistics Canada, 2017). ...
... Columbia are Atlantic (Statistics Canada, 2017), there is growing apprehension that escapees and the introduction of novel diseases could be implicated in the diminishing numbers of wild Chinook salmon (reviewed by Noakes et al., 2000;Naylor et al., 2003;Ayer & Tyedmers, 2009). All of these concerns have resulted in increased public awareness promoting the culture of Chinook salmon on the West coast to hopefully ease some of the pressure experienced by wild populations. ...
... However, major declines in many salmonid populations have been observed throughout their ranges. Significant declines in the Pacific salmonids have occurred in the North American Pacific, with the total Canadian salmon catch reaching an historic low in 1998 (Noakes et al., 2000). Coho, Oncorhynchus kisutch, and Chinook, O. tshawytscha, salmon populations are particularly adversely affected (Brown et al., 1994;Noakes et al., 2000;Yoshiyama et al., 1998) with Coho numbers being less than 6% of pre-1940 levels (Brown et al., 1994). ...
... Significant declines in the Pacific salmonids have occurred in the North American Pacific, with the total Canadian salmon catch reaching an historic low in 1998 (Noakes et al., 2000). Coho, Oncorhynchus kisutch, and Chinook, O. tshawytscha, salmon populations are particularly adversely affected (Brown et al., 1994;Noakes et al., 2000;Yoshiyama et al., 1998) with Coho numbers being less than 6% of pre-1940 levels (Brown et al., 1994). In the USA a number of salmonids are recognised as endangered including the Atlantic, Salmo salar, Chinook, O. tshawytscha, Coho, O. kisutch, Sockeye, O. nerka, and Chum, O. keta, salmon (U.S. Fish and Wildlife Service, 2010). ...
Anthropogenic use of waterways is reducing connectivity at a rate faster than any time in geological history, sometimes causing serious declines in fish populations. Free passage of fish throughout the watercourse is necessary for species utilising different habitats for e.g. residing, spawning and feeding. Fish passes are employed to mitigate for impoundments, but are historically biased in design towards upstream migrating salmonids. Driven partly by more holistic environmental legislation, there is now an increasing interest in other species and life-stages, requiring development of fish passage criteria for multiple species during up- and down-stream migrations. To address these knowledge gaps this research programme undertook laboratory experiments with upstream migrant river lamprey, Lampetra fluviatilis, and downstream migrating European eel, Anguilla anguilla, and brown trout, Salmo trutta. The use of a large open-channel flume allowed control of the motivational state of, and stimuli encountered by the fish. The fish responses to a variety of model weirs and screens placed in the flume were assessed, allowing attainment of species and life-stage specific swimming capability and behavioural information. This research demonstrated that using large flumes where volitional swimming allows natural compensatory behaviours to be undertaken, provides more realistic swimming capability information for fish pass criteria than some traditional methods (i.e. confined swim chambers). Dependent on species and direction of movement, all structures tested had some level of impediment to migration, with small gauging weirs almost completely impeding movement of upstream migrant river lamprey under the conditions presented. Downstream migrant anguilliforms were seen to demonstrate structure oriented, thigmotactic behaviour compared to salmonids which responded to flow fields. Under high velocities, this lack of reaction to hydraulic cues may result in a higher probability of damage and mortality at facilities traditionally designed to protect salmonids. The information provided by this research, e.g. accurate swimming speeds and fish response to associated hydraulic conditions, will aid the production of effective multi-species fish pass facilities
... Chinook and coho fisheries are managed to achieve specified harvest rates although escapement goals have also been established for a few key stocks. As part of an overall management strategy, Canada has maintained an extensive salmon enhancement program since the late 1970s producing on average 485 million salmon in various enhancement projects (Noakes et al. 2000). The vast majority (425 million) of these enhanced salmon are produced to support commercial sockeye, chum and pink salmon fisheries. ...
... This extreme economic dichotomy undoubtedly influenced the attitude of many in the salmon fishing industry and contributed, in part, to the strong negative views expressed towards the salmon farming industry by the fishing sector and others. The reality is that these changes in both abundance and price would have occurred regardless of the development of aquaculture in British Columbia given the global nature of the seafood industry and the natural forces governing the production of wild salmon (Noakes et al. 2000). Salmon farming has outperformed virtually every other industry in the British Columbia economy since 1985 and farm salmon is currently the province's largest agricultural export. ...
... Denson et al. 2012), would allow identification of natural recruitment in a population allowing adaptive decision making for fishery managers. Such programs are already in place for salmonid fisheries in North America (see Noakes et al. 2000; Rawding et al. 2012 ). Information collected from these programs identified that hatchery fish had replaced wild fish, with management intervention required to protect wild stocks (Noakes et al. 2000). ...
... Such programs are already in place for salmonid fisheries in North America (see Noakes et al. 2000; Rawding et al. 2012 ). Information collected from these programs identified that hatchery fish had replaced wild fish, with management intervention required to protect wild stocks (Noakes et al. 2000). Murray cod and golden perch stocking effectiveness Marine and Freshwater Research G Whilst our study shows that marked fish make a substantial contribution to populations in the receiving ecosystems, there is a range of undesirable outcomes that may be associated with the presence of stocked fish, including replacement of wild with stocked fish (whether by direct stocking, or indirectly through the progeny of previously stocked fish), reduced local genetic heterogeneity, loss of local adaptations, domestication and introduction of infectious diseases and non-target species (Rowland 2013). ...
Stock enhancement is a management tool used for fishery recovery worldwide, yet the success of many stocking programs remains unquantified. Murray cod (Maccullochella peelii) and golden perch (Macquaria ambigua) are important Australian recreational target species that have experienced widespread decline. Stocking of these species has been undertaken for decades, with limited assessment of effectiveness. A batch marking and recapture approach was applied to assess stocked Murray cod and golden perch survival, contributions to wild fisheries, and condition in rivers and impoundments. Stocked fish were marked with calcein. Marked fish were detected during surveys undertaken 3 years and 10 months from initial marking, and it is probable that marks will persist beyond this time. The proportion of calcein marked fish in the population sub-sample whose age was equal to, or less than, the number of years since release, varied by 7–94% for Murray cod, and 9–98% for golden perch. Higher proportions of marked fish were found in impoundments than rivers. Marked Murray cod had significantly steeper length–weight relationships (i.e. higher weight at a given length) to unmarked fish. Our results show that application of methods for discriminating stocked and wild fish provides critical information for the development of adaptive, location-specific stocking strategies.
... Of the 65 lakes that could be assessed in the central and north coastal regions, 34% were categorized as depressed, indicating they were less than 25% of their base abundance (Riddell 2004). Pacific salmon stocks along the West Coast of Canada have been in sharp decline since the early 1990's (Noakes et al. 2000). In 1993, the National Marine Fisheries Service initiated a status review of coho salmon in Washington, Oregon, and California in response to petitions seeking protection for coho salmon under the Endangered Species Act. ...
... It was determined that the natural populations of coho salmon along the California coast were in danger of extinction, while populations along the Washington and Oregon coast lines were likely to become endangered in the foreseeable future (Weitkamp et al. 1995). Noakes et al. (2000) reasoned that the most likely causes for the decline in Pacific salmon stocks were a combination of overfishing, climate change and freshwater habitat destruction. Large-scale salmon enhancement projects have been in place to help curtail the declining salmon populations (Lackey 2009b). ...
... By 1999, the farming of salmonid fish alone accounted for 68,000 t (74%) of the total aquaculture tonnage and 92% of the industry's value (DFO, 2000c). Among these fish, Atlantic salmon was by far and away the most highly farmed species, with production estimates of 22,610 t in Atlantic Canada (Whoriskey, 2000) and 30,165 t in British Columbia (Noakes et al., 2000) in 1998. Worldwide, the production of farmed Atlantic salmon has exceeded that of all other organisms reared in aquaculture facilities, experiencing a rate of increase of 22.4% per annum (Naylor et al., 2000). ...
... In the only Canadian river (Magaguadavic River, New Brunswick) for which annual data on escaped cultured fish and wild fish exist, the number of cultured fish entering the river between 1992 and 1999 has been two to eight times that of the wild salmon returning to the same river to spawn (Carr et al., 1997;Whoriskey, 2000). On the Pacific coast, the numbers of Atlantic salmon escaping into British Columbia waters averaged 43,863 per annum between 1994 and 1998 (Noakes et al., 2000); an estimated 32,000 to 86,000 farmed Atlantic salmon escaped from netpens between January and September 2000 (Mickleburgh, 2000;Sullivan, 2000). Concomitant with the increased aquaculture production of Atlantic salmon in Pacific waters is evidence of natural spawning by escaped members of this exotic species in British Columbia rivers (Gross, 2000;Volpe et al., 2000). ...
... An in-depth analysis of the distribution of salmonid production across the world reveals that certain regions contain a significantly higher concentration than others. Norway and Chile are two of the most prominent players in this industry, with 36% and 19% of the world's production, respectively (Noakes et al., 2000;Buschmann et al., 2006;Mou, 2013). The current dominance in this regard may be primarily attributed to the vast and diversified marine ecosystems that are prominent within these countries, in addition to the progressive aquaculture policies that are in place. ...
Analysis of economic profitability is essential for establishing the financial viability of any business enterprise. In the context of trout farming in the Pakistani district of Chitral, this study evaluates the financial implications of this profitable and sustainable technique. In July of 2020, a structured questionnaire was used to collect data on profitability indicators for the study. The investigation reveals that the overall cost of producing 398 kilograms of fish on the farm was 596,013 rupees. This cost analysis offers great insight into the economic ramifications of trout farming in the region. In addition, the study indicates a good Benefit-cost ratio of 1.67, demonstrating that the benefits of trout farming outweigh the associated expenses. Additionally, the Rate of Return on Investment (RRI) is an amazing 0.78, further demonstrating the enterprise's profitability. The Variable Cost (RVC), which has a large value of 0.60, is one of the main aspects that contribute to the profitability of trout farming. This illustrates the potential profitability and cost-effectiveness of trout farming in District Chitral. The study demonstrates that fish farming, specifically trout farming, offers individuals a lucrative option to support themselves. With its favorable financial indicators and potential for long-term profitability, trout farming is a viable source of income for residents in the region.
... In March, the Strait of Georgia, the Vancouver Island shelf, and the east coast of Haida Gwaii experienced increased Chl-a concentrations. In April and May (spring) and sustained over June-August (summer), we observed an apparent intensification of Chl-a concentration along the shelf, particularly in the vicinity of Vancouver Island, agreeing well with previous studies (Noakes et al., 2000;Masson and Peña, 2009;Jackson et al., 2015;Giannini et al., 2021). In contrast to the coastal region, moderate Chl-a concentrations were found along the continental slope, and low Chl-a concentrations were found in offshore waters (Fig. 3D). ...
Phytoplankton phenology describes yearly algal growth cycles and characterises the timing, duration, and magnitude of bloom occurrences. This study used satellite chlorophyll-a data from 1998 to 2020 and the Hierarchical Agglomerative Clustering method to define phenoregions based on phytoplankton phenology spatial patterns over the British Columbia and Southeast Alaska coastal oceans. The defined phenoregions were used to simplify the spatial complexity of the heterogenous study region and thus better describe phytoplankton seasonality across the target area. The cluster analysis allowed the delineation of four coherent regions: two coastal regions and northern and southern shelf/offshore regions. Results showed that each phenoregion had distinguishable phytoplankton phenological characteristics likely due to different physical forcings acting in these areas. Moreover, the interannual variability of the spring bloom initiation was evaluated considering interactions between sea surface temperature (SST) anomalies and the El Niño Southern Oscillation Index (ENSO). Early spring blooms were associated with positive SST anomalies and El Niño conditions; conversely, average or late spring blooms occurred in years with negative SST anomalies and La Niña conditions, with the strongest relationship occurring in the southern shelf/offshore phenoregion. This study provided new insights into the regionalisation of the British Columbia and Southeast Alaska coastal oceans based on phytoplankton phenology patterns. Given the critical role of phytoplankton as the base of the marine food web, such phenoregions have implications for regional zooplankton biomass and fish production. The link between phytoplankton phenology and climate drivers points to the importance of environmental change in phytoplankton bloom dynamics. Further research into the connection between phytoplankton bloom indices and zooplankton community structure and production would be an important step toward using these indices for ecosystem monitoring and fisheries management.
... Second, more detailed assessments of salmon resilience are needed within species (e.g., by population, by Conservation Unit). Overall salmon abundance has been in decline along Canada's West Coast since the 1990s (Noakes et al. 2000;Price et al. 2017), and the impacts of these changes (e.g., presence/absence of certain stocks and certainty of runs) have wide-reaching implications for many whose lives and livelihoods intersect with Pacific salmon. For many Indigenous Nations across the Pacific Northwest, uncertainty around annual salmon returns poses a significant concern (CRITFC 2021; Reid et al. 2022). ...
A major challenge in contemporary aquatic environmental management is anticipating and responding to increasing social-ecological uncertainty and shifts in the health of managed species. Signals indicate that many wild North American Pacific salmon populations are in or at risk of decline, but the mechanisms affecting salmon resilience are not clear. There is a need to assess the resilience of species and stocks across the Pacific region from the perspective of groups involved in salmon work to direct effective management responses. Interviews were conducted with individuals (N = 32) holding diverse knowledges and salmon expertise including employees of federal government fisheries management organizations, non-governmental organizations, Indigenous agencies, and universities, to understand how perceptions of salmon resilience in the Pacific Northwest are changing over time, the factors that positively or negatively affect vulnerability and resilience, and variations across Pacific salmon species and stocks. We find that Pacific salmon resilience is negatively affected by interacting biological, environmental, and social pressures, with life history, geography, and increasing water temperatures viewed as the most significant drivers of declining resilience. Chinook and sockeye salmon are perceived as the most vulnerable and the most socially valued species, compounding the challenges for fisheries management and conservation. Species seen as highly resilient (chum and pink salmon) are viewed as being at risk of future increases in vulnerability if increasing conservation measures for more vulnerable species shift harvesting pressures towards more abundant species. We conclude by outlining anticipated social-ecological changes facing Pacific salmon and discuss areas of consensus for salmon conservation needs.
... However, this is rapidly changing as declining numbers in natural populations have resulted in the inability of fisheries to meet the rising demands for Chinook salmon consumption [18,20,48]. Additionally, since the most commonly farmed salmonid in British Columbia is the non-native Atlantic salmon, Salmo salar [40], there is growing apprehension that escapees and the introduction of novel infections could be implicated in the diminishing numbers of wild Chinook salmon (reviewed by [2,25,27]). These concerns have resulted in increased public awareness promoting the commercial culture of Chinook salmon on the West coast to hopefully ease some of the pressure experienced by wild populations. ...
... Elevated predation risk is a major concern for diadromous salmonids given their social and ecological importance (Lewis et al. 2019;Mortelliti 2023) and population declines (Noakes et al. 2000;Waldman and Quinn 2022). These fishes are highly susceptible to predation during smolt migration when they encounter a suite of novel predator species (Osterback et al. 2013;Gibson et al. 2015;Flávio et al. 2021). ...
Diadromous fish populations have incurred precipitous declines across the globe. Among many stressors, these species are threatened by anthropogenic barriers that impede movement, alter riverine habitat, and augment predator communities. In this study, we used acoustic transmitters (n = 220) with predation and temperature sensors to characterize Atlantic salmon (Salmo salar) smolt predation risk in the Penobscot River, Maine, USA. Across two seasons, we documented 79 predation events through a 170 km migratory pathway, which included three hydropower projects and a large estuary. We detected tagged smolts that were predated by fish (n = 42), marine mammals (n = 28), and birds (n = 9). Using a multistate mark-recapture framework, we estimated that 46% of smolts were predated during downstream migration, which accounted for at least 55% of all mortality. Relative predation risk was greatest through impoundments and the lower estuary, where on average, predation rates were 4.8-fold and 9.0-fold greater than free-flowing reaches, respectively. These results suggest that predation pressure on Atlantic salmon smolts is exacerbated by hydropower projects and that predation in the lower estuary may be greater than expected.
... The abundance of wild salmon has declined dramatically since the 1980s (Kellogg 1999, Noakes, Beamish et al. 2000, Torrissen, Jones et al. 2013, NASCO 2019. This global decline is due mainly to poor marine survival (ICES 2016) caused by the complex interaction of anthropogenic, natural biological, and physical factors, including sea-temperature change, pollution, susceptibility to predators, and post-smolt growth ( Fig. 1) (Friedland, Reddin et al. 1993, Parrish, Behnke et al. 1998, Jonsson and Jonsson 2004, Friedland, MacLean et al. 2009, Chaput 2012, Friedland, Shank et al. 2014, Vollset, Krontveit et al. 2015. ...
The proliferation of sea lice from aquaculture may substantially aggravate the decline in marine survival of wild salmons. In some countries, this risk has motivated regulators to adopt more precautionary policies; in other countries, however, regulators have disputed the need for stricter regulation. This article compares the sea-lice regulations of Norway, Scotland, Ireland, and Canada (British Columbia), showing how varying interpretations of the science on farm–wild interactions have shaped efforts to scale up regulatory measures for mitigating health hazards and mortality risks for wild salmon. In Norway and Scotland, scientific consensus has expedited cooperation between research and governing institutions and facilitated ambitious policy reforms. In Ireland and Canada, by contrast, scientific controversy around the scale of farm-lice impacts on wild salmon populations has led to conflict and disagreement between researchers and policymakers, and to failure of reform attempts desired by wild salmon stakeholders.
... Thus there is a lack of knowledge regarding the early marine stage in transitional waters (Welch et al. 2009), despite speculation that mortality in this phase could be high due to the high levels of human activity and other pressures concentrated in estuaries and coastal waters (Thorstad et al. 2012). While migrating to sea, juvenile anadromous fish face multiple natural (salinity and temperature gradients, predation) and anthropogenic (fishing activities, migratory barriers, coastal developments) challenges (Ruggles 1980, Noakes et al. 2000, Clarke et al. 2021) that should be better understood to enable effective management and conservation of salmonid populations (Lacroix 2008, Welch et al. 2009, Holbrook et al. 2011. ...
Monitoring the first seaward migration of juvenile salmonids, known as smolts, is challenging because there is limited tracking technology suited to their small size. Nevertheless, for their management and conservation purpose, it is critical to understand this phase of their life cycle when they adapt to increased salinity, novel predators and new prey. Smolts of 2 species, Atlantic salmon Salmo salar and brown trout Salmo trutta , were acoustically monitored at 4 study sites, together with biotic and abiotic parameters, to estimate and explain their survival during their estuarine migration to sea. The 2 species exhibited different levels of survival during this seaward migration, with a higher survival for trout smolts. For both species, survival was similar among 3 of the 4 sites. Migration speed and migratory distance influenced smolt estuarine survival, but body length, body condition, sex, age, and environmental parameters (temperature, salinity, dissolved oxygen) did not. Migration speed, potentially reflecting smolts’ capacity to avoid predators or escape dangerous areas, had a positive effect on their survival. Increased distance negatively influenced estuarine survival, which could lead to lower survival rate in the River Frome Estuary where orientation is more difficult for smolts due to widely separated environmental cues. Overall, smolt survival through estuaries was estimated between 51 and 97% among 4 populations, suggesting that estuaries are variably challenging environments for migrating smolts, accounting for non-negligible early marine survival. Understanding which estuaries have low survival and why is imperative to prioritise management actions.
... The GlobColour interpolated Chl-a product demonstrated the expected seasonal and local dynamics for this region, as well as average concentrations within ranges reported for satellite-derived observations [17,18,29,30,65,66] and in situ measurements [32]. For instance, this region typically experiences maximum Chl-a concentrations in the spring and summer [17,18,29,30,32,67,68], with a secondary fall bloom being observed in the B.C. coastal waters [18,30,69], which was particularly evident in the vicinity of Calvert Island (51.5 • N; Figure 4C, coast). Along the continental shelf, the west coast of Vancouver Island experienced relatively higher Chl-a concentrations (maximum of 3.4 ± 3.9 mg m −3 ; 50 • N, Figure 4A-C, shelf), consistent with reported concentration ranges and bloom timing [18,69]. ...
Phytoplankton phenology studies require a dataset that is continuous in time and space since missing data have been shown to affect the accuracy of seasonality metrics. The interpolated GlobColour product provided by the Copernicus Marine Environment Monitoring Service (CMEMS) meets these requirements by being ‘gap filled’, thus yielding the highest spatial coverage. Despite being validated on a global scale, a regional comparison to in situ Chl-a concentrations should be conducted to enable product application in optically complex waters. This study aims to evaluate the performance of the GlobColour interpolated product in British Columbia coastal waters via a statistical match-up analysis and a qualitative analysis to determine whether the data reflect the region’s large-scale seasonal trends and latitudinal dynamics. Additionally, the statistical performance of the GlobColour interpolated product was compared to the original GlobColour and Ocean Colour Climate Change Initiative (OC-CCI) merged chlorophyll-a products based on in situ observations. The GlobColour interpolated product performed relatively well and was comparable to the best-performing product for each water type (RMSE = 0.28, r2 = 0.77, MdAD = 1.5, BIAS = 0.90). The statistics for all the products degraded in Case 2 waters, thus highlighting the dilemma of applying algorithms designed for Case 1 waters in Case 2 waters. Our results indicate how the quality of products can vary in different environmental conditions.
... Recent evidence of transmission of infectious agents between farmed and wild salmon Bateman et al. 2022), and the growing body of evidence linking individual agents to disease (Di Cicco et al. 2018;Santos et al. 2019;Valdes et al. 2021), confirm that farm-origin pathogens must be considered when assessing the cause of poor early marine survival of wild BC salmon and associated population declines (Noakes et al. 2000;Peterman and Dorner 2012;Riddell et al. 2013;Bendriem et al. 2019) that have failed to rebound despite significant reduction in fishing pressure (Walters et al. 2019). Passive release of infectious agents directly into wild salmon habitat is an important transmission pathway that can be measured through filtration of water samples. ...
The growth of the net pen salmon farming industry and the concurrent decline of many wild salmon populations have generated an ongoing call for research into the potential role of infectious agents associated with salmon farming. Here, we describe a method to screen for the presence of viral nucleic acids by sampling biological waste in the vicinity of farms. We collected biological samples adjacent to 56 marine net pens from five different companies, and two farm salmon processing plants (n = 230), 70% of samples were positive for Piscine orthoreovirus-1 (PRV-1). Viral genome segments S1 (n = 68) and M2 (n = 39) were sequenced and subjected to phylogenetic analysis. Sequences were all monophyletic to the clade of PRV-1 routinely found in the region. Consistent with previous studies, samples collected near Atlantic salmon (Salmo salar) farms were related to a lineage of PRV-1a commonly detected in both farmed and wild salmon in British Columbia, while a related lineage of PRV-1a was detected near Chinook salmon (Oncorhynchus tshawytscha) farms. Similarity in sequence within companies suggests that Atlantic salmon freshwater hatcheries are a probable source of this virus to the marine environment, concordant with recent detections of PRV-1 within those hatcheries.
... Chinook salmon (Oncorhynchus tshawytscha) are an anadromous fish species native to the North Pacific Ocean that have faced major population reductions under increasing anthropogenic stress (Yoshiyama et al., 1998;Noakes et al., 2000). The Sacramento-San Joaquin River Basin (SSJRB) of California supports some of the most heavily impacted populations of Chinook salmon, where there are four seasonal runs: fall, late-fall, winter and spring-the latter two of which are endangered and threatened, respectively (Moyle et al., 2017). ...
Juvenile fall-run Chinook salmon (Oncorhynchus tshawytscha) in the Sacramento–San Joaquin River Basin experience temporally and spatially heterogenous temperature regimes, between cool upper tributaries and the warm channelized Delta, during freshwater rearing and outmigration. Limited water resources necessitate human management of dam releases, allowing temperature modifications. The objective of this study was to examine the effect of temperature on specific dynamic action (SDA), or the metabolic cost associated with feeding and digestion, which is thought to represent a substantial portion of fish energy budgets. Measuring SDA with respect to absolute aerobic scope (AAS), estimated by the difference between maximum metabolic rate (MMR) and standard metabolic rate (SMR), provides a snapshot of its respective energy allocation. Fish were acclimated to 16°C, raised or lowered to each acute temperature (13°C, 16°C, 19°C, 22°C or 24°C), then fed a meal of commercial pellets weighing 2% of their wet mass. We detected a significant positive effect of temperature on SMR and MMR, but not on AAS. As expected, there was no significant effect of temperature on the total O2 cost of digestion, but unlike other studies, we did not see a significant difference in duration, peak metabolic rate standardized to SMR, time to peak, percent of meal energy utilized, nor the ratio of peak O2 consumption to SMR. Peak O2 consumption represented 10.4–14.5% of AAS leaving a large amount of aerobic capacity available for other activities, and meal energy utilized for digestion ranged from 5.7% to 7.2%, leaving substantial remaining energy to potentially assimilate for growth. Our juvenile fall-run Chinook salmon exhibited thermal stability in their SDA response, which may play a role in maintaining homeostasis of digestive capability in a highly heterogeneous thermal environment where rapid growth is important for successful competition with conspecifics and for avoiding predation.
... Salmonid species spanning the West Coast of the United States and upward toward southern British Columbia as well as those distributed along the East Coast of the United States have experienced extensive and ongoing declines throughout their native range (Parrish et al. 1998;Noakes et al. 2000;Gustafson et al. 2007). Numerous efforts have been enacted to Abstract Several studies have demonstrated lower fitness of salmonids born and reared in a hatchery setting compared to those born in nature, yet broad-scale genome-wide genetic differences between hatcheryorigin and natural-origin fish have remained largely undetected. ...
Several studies have demonstrated lower fitness of salmonids born and reared in a hatchery setting compared to those born in nature, yet broad-scale genome-wide genetic differences between hatchery-origin and natural-origin fish have remained largely undetected. Recent research efforts have focused on using epigenetic tools to explore the role of heritable changes outside of genetic variation in response to hatchery rearing. We synthesized the results from salmonid studies that have directly compared methylation differences between hatchery-origin and natural-origin fish. Overall, the majority of studies found substantial differences in methylation patterns and overlap in functional genomic regions between hatchery-origin and natural-origin fish which have been replicated in parallel across geographical locations. Epigenetic differences were consistently found in the sperm of hatchery-origin versus natural-origin fish along with evidence for maternal effects, providing a potential source of multigenerational transmission. While there were clear epigenetic differences in gametic lines between hatchery-origin and natural-origin fish, only a limited number explored the potential mechanisms explaining these differences. We outline opportunities for epigenetics to inform salmonid breeding and rearing practices and to mitigate for fitness differences between hatchery-origin and natural-origin fish. We then provide possible explanations and avenues of future epigenetics research in salmonid supplementation programs, including: 1) further exploration of the factors in early development shaping epigenetic differences, 2) understanding the functional genomic changes that are occurring in response to epigenetic changes, 3) elucidating the relationship between epigenetics, phenotypic variation, and fitness, and 4) determining heritability of epigenetic marks along with persistence of marks across generations.
... Étant donné le contexte particulier d'émergence de l'industrie piscicole sur la côte ouest, justifiée au départ comme une solution révolutionnaire au problème de l'épuisement des stocks de poissons dans les océans, et les fortes critiques qui s'ensuivirent à son égard, il n'est pas vraiment étonnant que celle-ci intéressât de nombreux chercheurs en environnement et en biologie au début des années 2000. En effet, l'industrie piscicole fut l'objet de nombreuses recherches dans un ensemble de champs connexes à ces domaines (gestion halieutique, environnement, écologie, biologie, virologie, etc.) qui s'intéressèrent notamment aux impacts environnementaux et sur la santé humaine d'une telle pratique(voir, par exemple, deBruyn et al., 2006;Hites et al, 2004; Krkošek et al., 2006;Krkošek et al., 2010;Maurstad et al., 2007;Noakes et al., 2000;Saksida et al., 2007;Skall et al., 2005;Sutherland et al., 2001). Bien que l'on puisse observer quelques rares contradictions au sein de ces études, la grande majorité d'entre elles ont démontré les impacts néfastes des fermes salmonicoles sur les écosystèmes qui les entourent, ces impacts ayant été survolés dans le premier chapitre de ce mémoire. ...
//RÉSUMÉ//
Cette recherche vise à mieux comprendre les frictions occasionnées par la présence de l’industrie salmonicole sur les territoires ancestraux des nations kwakwaka’wakw et nuu-chah-nulth de l’île de Vancouver. Alors que le contexte à l’étude a déjà fait l’objet de nombreuses recherches, la question des rapports entre les humains et les poissons fut généralement mise de côté. En ce sens, le présent mémoire cherche à combler cet important fossé. J’avance la proposition selon laquelle l’introduction de l’industrie salmonicole sur les territoires autochtones de l’île de Vancouver serait instigatrice d’importantes frictions entre des manières bien distinctes d’appréhender les rapports aux poissons, les frictions étant ici comprises comme des lieux fertiles à partir desquels de nouvelles dynamiques culturelles et de nouvelles structures de pouvoir voient le jour.
La présente recherche ayant été effectuée en plein coeur de la pandémie associée au COVID-19, l’enquête ethnographique sur le terrain ne put être réalisée. Conséquemment, dans ce mémoire, je propose une analyse originale principalement fondée sur des données puisées dans un large corpus de littérature anthropologique et autochtone et sur des informations publiquement accessibles à distance via les réseaux sociaux et les cyberespaces. L’ensemble des données analysées appuient la proposition selon laquelle le contexte à l’étude serait au coeur d’importantes frictions entre deux régimes de valeur qui guident les rapports avec le poisson : d’abord, un régime de valeur traditionnel associé aux règles réciproques d’interaction, de prédation et de partage avec les chefs des peuples autres qu’humains qu’ils représentent et incarnent; ensuite, un régime de valeur marchande faisant sens dans une économie de marché capitaliste globalisée et globalisante. L’exemple de la résurgence de la First Salmon Ceremony, qui est présenté en conclusion, vient appuyer cette proposition. En effet, elle se présente comme un lieu d’affirmation, de négociation et de revendication politique, territoriale et identitaire important, et témoigne d’une continuité transformative caractéristique des cosmopolitiques autochtones contemporaines de la côte ouest. En plus de proposer de nouvelles pistes de recherche, ce mémoire constitue une invitation à repenser les logiques et les structures de pouvoir qui guident actuellement la gestion halieutique au sein des territoires autochtones du pays.
Mots-clés : anthropologie, ethnologie, autochtones, Ouest canadien, salmoniculture, personnes autres qu’humaines, poisson, frictions, enchevêtrements, régimes de valeur.
//ABSTRACT//
This research aims to better understand the frictions caused by the introduction of the salmon farming industry on the ancestral territories of the kwakwaka’wakw and nuu-chah-nulth nations of Vancouver Island. While this context has already been the subject of much research, the question of the relationship between humans and fish was generally put aside. In that sense, this thesis seeks to bridge this important gap. While the frictions are understood here as fertile places from which new arrangements of culture and power are born, I propose that the introduction of the salmon farming industry into the indigenous territories of Vancouver Island instigated significant frictions between different ways of understanding the relationships with fish.
Because this research was conducted in the midst of the COVID-19 pandemic, an ethnographic field investigation could not be carried out. Consequently, in this thesis, I propose an original analysis mainly based on data drawn from a large corpus of anthropological and indigenous literature, but also on publicly accessible information from social networks and cyberspaces. All of the data analyzed support the proposition that the context under study is, in fact, instigating important frictions between two value regimes that guide relationships with fish: First, a traditional value regime associated with the reciprocal rules of interaction, predation and sharing with the chiefs of the other-than-human peoples they represent and embody; Then, a regime of market value making sense in a globalized and globalizing capitalist market economy. The example of the resurgence of the First Salmon Ceremony presented in the conclusion supports this proposition. In fact, it presents itself as an important space for political, territorial and identity claims, negotiation, and affirmation, while testifying the transformative continuity that characterize contemporary West Coast indigenous cosmopolitics. In addition to proposing new avenues of research, this paper is an invitation to rethink the logics and power structures that currently guide halieutic management within the indigenous territories of Canada.
Keywords: anthropology, ethnology, First Nations, Northwest coast, salmon farming, other-than-human persons, fish, frictions, entanglements, value regimes.
... Coasts of Canada. However, because Atlantic salmon are not indigenous to the West Coast, there is public concern regarding the introduction of foreign diseases to wild populations as well as the exposure of native salmon species to competition with farmed Atlantic salmon escapees (reviewed by Noakes et al., 2000). Despite the negative publicity associated with farming Atlantic salmon on the West Coast, a staggering 71% of Canadian Atlantic salmon production occurs in British Columbia (BC, Statistics Canada, 2017). ...
Aquaculture in North America is currently dominated by Atlantic salmon, but there has been an increasing interest in the production of species native to the Pacific coast. Chinook salmon is relatively new to production; therefore, the selection of appropriate stocks is critical. Often genes from wild populations are incorporated into farmed stocks to avoid performance decreases associated with inbreeding. The present study focuses on assessing the immunological performance of one inbred stock and seven outbred/hybrid crosses after challenge with the marine pathogen, Vibrio anguillarum. Throughout exposure challenge to both pathogen and sterile PBS, significant differences in mortality were observed between crosses. Fish were also assessed for major histocompatibility complex (MHC) class II β1 genotype, and although particular alleles did not confer resistance, crosses with better survival had more individuals present-ing a heterozygous genotype. The stress induced during infection resulted in several individuals presenting signs of Bacterial Kidney Disease (Renibacterium salmoninarum) indicating that chronic co- infection may have contributed to susceptibility. When spleen samples from the highest and lowest performing hybrid crosses were assessed for cytokine and respiratory burst gene expression throughout bacterial challenge, high surviving crosses presented lower expression of inflammatory cytokine transcripts (IL- 1β, IL- 6 and TNFα) when compared to low performing crosses. Interestingly, microsatellite analysis revealed no significant differences in inbreeding coefficient or allelic richness between crosses despite observed variation in immune performance. Understanding the impact of outbreeding on the immune function of farmed, and often inbred, Chinook salmon could aid in future development of high-quality aquaculture stocks for this species.
... The GTA deems the cisgenic salmon as a GMO and it would be required to undergo the related assessments. We might consider at this point that there are instances of interspecific hybridisation between Pacific salmon including coho and Atlantic salmon (Blanc and Chevassus, 1979;Noakes, Beamish and Kent, 2000). If we recall the definition of 'modern biotechnology' in the Cartagena Protocol, the technique must be one that overcomes natural reproductive barriers. ...
Few species are as central to Norwegian society and culture as the potato and the Atlantic salmon. Yet these industries face considerable threats to production by pests, namely potato late blight (Phytophthora infestans) and sea lice (Lepeophtheirus salmonis). Current pest-control strategies, such as the use of fungicides and mechanical delousing methods, endanger the sectors' sustainability. Breeding for increased host resistance against these pests offers a strong preventative strategy to ensure future potato and Atlantic salmon production, in a sustainable way. Nevertheless, traditional breeding methods and GMO technology do not offer durable solutions for improved resistance. New breeding technologies like genome editing using CRISPR/Cas9 offer a unique, rapid solution to introduce much-needed resistance in these species. CRISPR technology revolutionises how we can target specific genes to strengthen host resistance. In potato, we explored how CRISPR may improve resistance by introducing race-specific (qualitative) and non-race-specific (quantitative) genes as well as by knocking out susceptibility genes. We further investigated how CRISPR may enable pyramiding of resistance and susceptibility genes to achieve durability against P. infestans. Research in Atlantic salmon shows that sea lice resistance can be explained by genetics but that it is a highly polygenic trait, with many genes having minor effects. CRISPR can be deployed as a way to study gene function to identify the causative DNA sequences underlying sea lice resistance. Once discovered, CRISPR can be used to promote certain alleles having the largest effects on resistance (PAGE method), or by harnessing genetic biodiversity from a closely related species (introgression-by-editing), or even by introducing small, novel insertions or mutations in the target genes. We found, however, that if the aim is to release an organism for cultivation and consumption, the type of changes to the DNA determines how that organism will navigate the legal framework. The Gene Technology Act determines that organisms edited using CRISPR are defined as GMO and must undergo the appropriate assessments for deliberate release. Part of that assessment investigates the organism’s contribution to sustainability, a criterion maintained in the Norwegian Biotechnology Advisory Board’s proposal for a tiered regulatory system. A potato demonstrating strong partial to complete resistance against late blight, with minor changes to its DNA might significantly reduce, possibly even eliminate, fungicide use, thereby providing food that positively impacts environmental health and sustainability. Farming of Atlantic salmon with improved resistance not only improves fish welfare and possibly the necessity for delousing, but it may also reduce the concentrating effect of infestations at farm sites and the resultant impacts on wild salmon populations. This thesis shows that with less risky genome edits, done with a sustainable purpose may pave the way for release approval under the Gene Technology Act, securing sustainable food production in Norway. We cannot, however, disrupt the status quo unless policymakers and regulators can strike a fine balance between regulating the risk and fostering technological innovation.
... There is no indication that continued stocking of hatchery-reared Chinook Salmon is necessary to provide a diverse fishery, and continued stocking may actually be detrimental to the fishery through the potential threat of disease introduction and negative genetic impacts to the naturalized populations (Schreiner et al. 2010). There are major concerns, and examples of transferring disease from hatchery-reared salmonids to wild populations (Pacific Northwest Fish Health Protection Committee 1989;Noakes et al. 2000). In the Great Lakes, BKD and whirling disease have already caused mortality in wild stocks, and there is continued concern surrounding Viral Hemorrhagic Septicemia (VHS), a virus that Chinook Salmon are vulnerable to (Phillips et al. 2014). ...
... nerka), and coho (O. kisutch) salmon, with some populations extirpated and others on the brink of extinction (2)(3)(4)(5). Resulting effects on the ecosystem are many. In particular, diminishing Chinook salmon populations contribute to declines in endangered Southern resident killer whales (Orcinus orca) (6). ...
Global expansion of aquaculture and agriculture facilitates disease emergence and catalyzes transmission to sympatric wildlife populations. The health of wild salmon stocks critically concerns Indigenous peoples, commercial and recreational fishers, and the general public. Despite potential impact of viral pathogens such as Piscine orthoreovirus-1 (PRV-1) on endangered wild salmon populations, their epidemiology in wild fish populations remains obscure, as does the role of aquaculture in global and local spread. Our phylogeographic analyses of PRV-1 suggest that development of Atlantic salmon aquaculture facilitated spread from Europe to the North and South East Pacific. Phylogenetic analysis and reverse transcription polymerase chain reaction surveillance further illuminate the circumstances of emergence of PRV-1 in the North East Pacific and provide strong evidence for Atlantic salmon aquaculture as a source of infection in wild Pacific salmon. PRV-1 is now an important infectious agent in critically endangered wild Pacific salmon populations, fueled by aquacultural transmission.
... As a result of governance changes, commercial fisheries, and other stressors like climate change and the loss of riverine and coastal habitats, Pacific salmon (Oncorhynchus spp.) and their fisheries are in serious decline in many regions compared to their historical abundance and catch (Kellogg 1999;Noakes et al. 2000;Bisson et al. 2009;Rensel et al. 2010;Katz et al. 2013;Gayeski et al. 2018;Walsh et al. 2020). Indeed, the 2019 commercial salmon season saw historical record low landings, across salmon management areas on the Central Coast (Areas 7-8: A-H; DFO 2019), and some did not receive a commercial fishery opening for chum, coho, or pink salmon. ...
Wild salmon are central to food security, cultural identity, and livelihoods of coastal Indigenous communities. Yet ongoing inequities in governance, declining fish populations, and mixed-stock ocean fisheries may pose challenges for equitable access between Indigenous fishers and other non-Indigenous fishers. We sought to understand current perceptions among Haíłzaqv (Heiltsuk) fishers towards salmon fisheries and their management. We conducted dockside surveys with both Haíłzaqv fishers and sport fishers, and in-depth interviews with Haíłzaqv fishers, community members, and natural resource managers. From these surveys and interviews we quantified satisfaction among both food, social, and ceremonial fishers and visiting recreational fishers with the current salmon fishery and associated social-ecological drivers, and characterized perceptions among Haíłzaqv people of salmon fisheries and management. Second, we synthesized community perceptions of the revitalization of terminal, communally run salmon fisheries within Haíłzaqv territory as a tool for their future salmon management. Finally, we elicited information from Haíłzaqv fishers about the barriers people in their community currently face in accessing salmon fisheries. Our findings suggest that low salmon abundance, increased fishing competition, and high costs associated with participation in marine mixed-stock fisheries currently hinder access and equity for Haíłzaqv fishers. This community-based research can help strengthen local, Indigenous-led management of salmon into the future.
... hypoxia, temperature change). Investigating the routes of exposure and the physiological impact of these toxins on salmon (and other marine organisms) will be an important part of understanding the ecosystem-level effects of harmful algal blooms in marine ecosystems, including their possible role in the decline of salmon populations (Noakes et al. 2000). ...
Report is on page 194-198.
In Saanich Inlet, biologically-relevant hypoxia exposure could not be calculated for the first time since ONC-VENUS monitoring began because of a 4-month data gap in the ONC-VENUS array, but appears synoptically similar to 2018.
Density of commercial shrimp (e.g. Spot Prawn Pandalus platyceros) has recovered to the benchmark period.
Sustained, low-level populations of new species (Armina californica and Pentamera cf. pseudocalcigera) remain in the community.
Recruitment of Sea Whip (Halipteris willemoesi) is the first indication of their potential to recover after a severe hypoxia-induced population crash, although they are still <8% of the population that existed before the benchmark period (2006-2013).
Recovery rate of the cold-water corals is substantially slower than the recovery of the habitat oxygen regime and the mobile species assemblage which have mostly returned to levels comparable to the benchmark period (2006-2013).
... We used the Fluidigm BioMark TM HD platform for measuring gene expression, a high-throughput microfluidics-based technology that can individually quantify 96 assays across 96 samples at once. We focused on these four groups because of their population declines in Southern British Columbia (BC), Canada and subsequent hatchery supplementation (Noakes et al., 2000;Beamish et al., 2009;DFO, 2013). In particular, the Sockeye salmon were from the endangered population of Cultus Lake, BC (COSEWIC, 2003). ...
Early marine survival of juvenile salmon is intimately associated with their physiological condition during smoltification and
ocean entry. Smoltification (parr–smolt transformation) is a developmental process that allows salmon to acquire seawater
tolerance in preparation for marine living. Traditionally, this developmental process has been monitored using gill Na+/K+ATPase
(NKA) activity or plasma hormones, but gill gene expression offers the possibility of another method. Here, we describe
the discovery of candidate genes from gill tissue for staging smoltification using comparisons of microarray studies with
particular focus on the commonalities between anadromous Rainbow trout and Sockeye salmon datasets, as well as a literature
comparison encompassing more species. A subset of 37 candidate genes mainly from the microarray analyses was used for
TaqMan quantitative PCR assay design and their expression patterns were validated using gill samples from four groups,
representing three species and two ecotypes: Coho salmon, Sockeye salmon, stream-type Chinook salmon and ocean-type
Chinook salmon. The best smoltification biomarkers, as measured by consistent changes across these four groups, were
genes involved in ion regulation, oxygen transport and immunity. Smoltification gene expression patterns (using the top 10
biomarkers) were confirmed by significant correlations with NKA activity and were associated with changes in body brightness,
caudal fin darkness and caudal peduncle length. We incorporate gene expression patterns of pre-smolt, smolt and de-smolt
trials from acute seawater transfers from a companion study to develop a preliminary seawater tolerance classification model
for ocean-type Chinook salmon. This work demonstrates the potential of gene expression biomarkers to stage smoltification
and classify juveniles as pre-smolt, smolt or de-smolt.
... For example, the ability to cope with and adapt to novel environments is especially important for captive rearing programmes that release animals into the wild. Production hatcheries are often used to rear fishes for release for a variety of reasons, including commercial, recreational, or tribal harvest opportunities, as well as management and reintroduction efforts for threatened and endangered populations (Mahnken et al., 1998;Noakes et al., 2000). Compared with the natural environment, conventional hatchery rearing often includes conditions that are uniform with reduced sensory stimuli. ...
We tested the prediction that a complex physical rearing environment would enhance short‐term spatial memory as assessed by learning ability in a spatial navigation task in juvenile Chinook salmon Oncorhynchus tshawytscha. We reared fish in two low‐density treatments, where fish were either in bare fiberglass tanks (bare) or in tanks with physical structure (complex). We also tested conventionally reared high‐density hatchery fish to compare with these other experimental treatments. Our reason for including this third hatchery treatment is that the two low‐density treatments, aside from the manipulation of structure, followed a rearing programme that is designed to produce fish with more wild‐like characteristics. We tested individually marked fish for seven consecutive days and recorded movement and time to exit a testing maze. Stimulus conspecific fish outside the exit of the maze provided positive reinforcement for test fish. Fish from the bare treatment were less likely to exit the start box compared with fish in the complex and hatchery treatments. However, fish in the hatchery treatment were significantly more likely to exit the maze on their own compared with both the bare and complex treatments. Hatchery fish effectively learned the task as shown by a decrease in the number of mistakes over time, but the number of mistakes was significantly greater on the first day of trials. Increasing habitat complexity with structure may not necessarily promote spatial learning ability, but differences between hatchery and experimental treatments in rearing density and motivation to be near conspecifics likely led to observed behavioural differences.
... Нерка и кокани при этом обычно формируют изолированные популяции за счет высокой ассортативности скрещивания и отбора против гибридов (Foote, Larkin, 1888;Wood, Foote, 1990, 1996. В северных широтах, в зоне экологического оптимума, нерка образует жилые формы только в изо- лированных озерах, недоступных для про- ходной формы (Остроумов, 1977;Куренков, 1979;Olsen et al., 2017). В открытых высо- кокормных экосистемах, например в камчат- ских озерах Дальнее, Копылье, Медвежье, нерка формирует «остаточные» группировки, представленные на 95% жилыми самцами, нерестящимися вместе с проходными рыба- ми (Крогиус и др., 1987; Маркевич и др., 2011). ...
Рассмотрены рыбохозяйственные риски создания стада проходной нерки Oncorhynchus nerka в бассейне оз. Кроноцкое с учетом мирового опыта строительства рыбоходов и организации ската молоди через опасные порожистые участки. На основе имеющегося опыта строительства и эксплуатации лососевых рыбоходов рассчитаны примерные размерные параметры сооружения, отличные от предложенных в изначальных проектах ТИНРО, Ленгидропроект, Гидрорыбпроект, Гипрорыбпром. По своим масштабам сооружение не имеет аналогов в мире. Определен круг трудноразрешимых проблем реализации проекта, требующих дополнительных исследований. Сделан прогноз трансформации экосистемы озера, предполагающий деградацию уникальной эндемичной фауны после вселения анадромных лососей. Сформированы основные позиции возможного использования современной фауны озера без антропогенного вмешательства. Ключевые слова: лестничный рыбоход, гидростроительство, нерка Oncorhynchus nerka, гольцы Salvelinus, биоразнообразие, оз. Кроноцкое, Камчатка.
... Pacific salmon have been an important staple for many Indigenous groups in the region for centuries. Yet due to climate change, overfishing, habitat destruction, and diseases introduced through the salmon farming industry, several species of Pacific salmon are currently listed as threatened (Gresh, Lichatowich, & Schoonmaker, 2000;Krkošek et al., 2000;Noakes, Beamish, & Kent, 2000). Similar concerns have been raised about many of the plant and animal species important to Indigenous food systems. ...
Indigenous knowledges are increasingly promoted within scholarship and policy making as a necessary component of the well-being and self-determination among Indigenous Peoples. This article contributes to this discussion by raising practical and ethical questions surrounding the resurgence of traditional food practices in Western Canada. Based on ethnographic fieldwork conducted with cultural activists and Elders in central Vancouver Island, this article reveals how this resurgence is framed by competing and contradictory pressures to build wider inclusion and awareness while simultaneously protecting knowledge and resources from exploitation. Due to this complication, it is imperative that scholars and policy makers develop and apply a more nuanced understanding of Indigenous knowledges in contemporary contexts that can better respond to the needs of Indigenous communities.
... Furthermore, the production of salmon in land-based systems has been shown to reduce eutrophication impacts which is important in a Swedish context (Emmelin and Cherp, 2016;Swedish Environmental Objectives, 2008). Other studies also suggest that conventional salmon farming increases the risk of contamination of bacteria to natural stocks of fish and other impacts to the environment (Buschmann et al., 2009;Naylor et al., 1998;Noakes et al., 2000). Thus, it will be important to further review the reduction of these impacts and pathogens to the environment and natural stocks in the area from land-based farming; and important that further sustainability indicators are used to assess IS networks, such the studied example in Sotenäs. ...
Available here for free until late September:
https://www.sciencedirect.com/science/article/pii/S0921344918302775
In order to enable industrial symbiosis (IS) as an approach for regional sustainable development, it is important that stakeholders involved in facilitating symbiotic exchanges can measure and comprehend the potential benefits and impacts. However, previous assessments have been sporadic and limited to only a few indicators, primarily focused only on existing IS examples or networks and very few have examined potential developments. This study expands the assessment of IS networks by reviewing the environmental and socioeconomic implications of an emerging network on the west coast of Sweden using life cycle assessment and socioeconomic assessments to illustrate the implications for the firms of the network and regional sustainability. The results suggest that the IS network has the potential to make a positive contribution to the environmental performance of the industries and the socioeconomic status of the region. Of key importance is the potential to cascade the use of nutrients and avoid large eutrophication impacts to the neighboring sea in addition to the large greenhouse gas emissions reductions by avoiding and replacing conventional processes and products. The socioeconomic assessment illustrated that the IS network could make a substantial contribution to the region for job creation, revenues, local skills base, research and innovation and regional identity. The results provide insights on the potential of industrial symbiosis for regional sustainable development, which may be important for decision makers, firms involved in the network and municipalities, nationally and internationally to advance local efforts with facilitating industrial symbiosis and to understand how these networks can be assessed.
... The expected changes in temperature and freshwater distribution and abundance over the next 30-50 years are so significant (BC Ministry of the Environment, 2016) that many Pacific salmon stocks are likely to see further declines with some stocks in the interior of British Columbia disappearing completely (Noakes and Beamish, 2011). Despite the lack of any credible scientific evidence to link declines in Pacific salmon stocks at a population level to salmon farming (Noakes et al., 2000;Noakes, 2011), those opposed to salmon farming and those wishing for a simplistic solution to restore Pacific salmon stocks to historic high levels suggest that removing salmon farms will accomplish that goal which it will not. This action will only serve to eliminate or significantly curtail the CAN$400m salmon farming industry in British Columbia which will have significant negative economic and social consequences for coastal communities and in particular First Nation communities involved in aquaculture. ...
Purpose
The world’s population is expected to increase by 30 percent to 10bn people by 2050 and with 70 percent of the earth’s surface covered by water aquaculture will play an important role in producing food for the future. The paper aims to discuss this issue.
Design/methodology/approach
While Canada has the longest coastline in the world by far (202,080 km) with 80,000 km of marine coastline capable of supporting aquaculture and fisheries, it ranks only 25th in terms of world aquaculture production. The reasons are many and varied, and this review examines statistical reports and publications to trace the beginnings of the aquaculture sector in Canada, and highlights some areas of strength and potential, and the challenges for future growth and expansion.
Findings
Currently, less than 1 percent of the 3.8m hectares of freshwater and marine areas that are considered suitable for seafood (i.e. finfish, shellfish and aquatic plants) production are being farmed so Canada has an ocean of opportunity to be a leader in world aquaculture production in the future.
Originality/value
The review highlights the need for a national strategic plan to increase aquaculture production in Canada and the need to simplify the current complex regulatory framework that has resulted in significant uncertainties and delays that have limited growth in this sector. The review highlights the potential and interest to triple current production while fostering greater involvement of First Nation communities.
... However, in addition to the increase in marine mammal predators, the Salish Sea and adjacent regions have seen other major ecosystem changes in the past four decades. These include increases in certain contaminates, introduction or proliferation of pathogens, habitat degradation, and changing ocean conditions, which all have the potential to impair the health and behavior of Chinook salmon in the early marine stage of life (Noakes et al. 2000;Magnusson and Hilborn 2003;O'Neill and West 2009;Irvine and Fukuwaka 2011). Therefore, it is conceivable that a composite of factors make juvenile Chinook salmon more vulnerable to predation by efficient, opportunistic predators like harbour seals. ...
Predation risk and competition among conspecifics significantly affect survival of juvenile salmon, but are rarely incorporated into models that predict recruitment in salmon populations. Using densities of harbour seals (Phoca vitulina) and numbers of hatchery-released Chinook salmon (Oncorhynchus tshawytscha) smolts as covariates in spatially structured Bayesian hierarchical stock–recruitment models, we found significant negative correlations between seal densities and productivity of Chinook salmon for 14 of 20 wild Chinook populations in the Pacific Northwest. Changes in numbers of seals since the 1970s were associated with a 74% decrease (95% CI: −85%, −64%) in maximum sustainable yield in Chinook stocks. In contrast, hatchery releases were significantly correlated with Chinook productivity in only one of 20 populations. Our findings are consistent with recent research on predator diets and bioenergetics modeling that suggest there is a relationship between harbour seal predation on juvenile Chinook and reduced marine survival in parts of the eastern Pacific. Forecasting, assessment, and recovery efforts for salmon populations of high conservation concern should thus consider including biotic factors, particularly predator–prey interactions.
... Eelgrass Zostera marina is the primary native seagrass species in estuaries across North America. In the face of large-scale eelgrass loss in many Pacific estuaries (e.g., Tallis et al. 2009; Thom et al. 2012) and drastically diminished returns of Pacific salmon across the West Coast of North America (Noakes et al. 2000), it is critical to understand how eelgrass habitat affects juvenile salmon prey provision. ...
The early marine period is a critical life history stage for growth and survival of anadromous juvenile Pacific salmon. The integrity of nearshore ecosystems where juvenile salmon reside and the capacity of these habitats to provide prey can thus influence overall salmon returns. Eelgrass Zostera marina beds in particular are considered critical nearshore habitat. By examining how juvenile salmon use this habitat during their early marine life, we gain insight into the trophic dynamics in these ecosystems and help gauge the effects of accelerating eelgrass loss and nearshore habitat development on juvenile salmon. This project investigated the role of eelgrass as juvenile salmon foraging habitat. We compared juvenile Chum Salmon Oncorhynchus keta and juvenile Chinook Salmon O. tshawytscha diets to prey availability in zooplankton tows and in epifaunal eelgrass samples across a gradient of eelgrass density in the Comox Estuary, British Columbia. Harpacticoid copepods dominated the diets of both juvenile Chum Salmon and Chinook Salmon and were found in abundance in eelgrass blades. We complemented diet analysis with carbon (δ13C) and nitrogen (δ15N) stable isotope analysis to examine the relative contribution of zooplankton, eelgrass epifaunal invertebrates, and terrestrial invertebrates to the diet of juvenile Chum Salmon. Juvenile Chum Salmon isotope ratios closely reflected those of eelgrass invertebrates, suggesting that eelgrass invertebrates made up approximately 80% of the diets of juvenile Chum Salmon. Our results highlight the value of eelgrass in providing nearshore foraging opportunities for juvenile salmon and suggest that eelgrass habitat protection and restoration may provide critical support for growth, thereby easing the transition of juvenile salmon from freshwater to the marine environment.
... A number of countries have been dependent on capture fisheries as the major source of fish for decades. Despite the worldwide increase in fish production, a decline has been observed in several cases (Burkhardt-Holm et al. 2002;Noakes et al. 2000) and this has been majorly attributed to over-fishing and climate-related threats. For Uganda in particular, production dropped from about 0.5 million tons in the year 2007 to only 0.38 million tons in 2010 amidst several efforts by the government to increase production (MAAIF 2012). ...
The intention of this study was to identify the bacterial pathogens infecting Oreochromis niloticus (Nile tilapia) and Clarias gariepinus (African catfish), and to establish the antibiotic susceptibility of fish bacteria in Uganda. A total of 288 fish samples from 40 fish farms (ponds, cages, and tanks) and 8 wild water sites were aseptically collected and bacteria isolated from the head kidney, liver, brain and spleen. The isolates were identified by their morphological characteristics, conventional biochemical tests and Analytical Profile Index test kits. Antibiotic susceptibility of selected bacteria was determined by the Kirby-Bauer disc diffusion method. The following well-known fish pathogens were identified at a farm prevalence of; Aeromonas hydrophila (43.8%), Aeromonas sobria (20.8%), Edwardsiella tarda (8.3%), Flavobacterium spp. (4.2%) and Streptococcus spp. (6.3%). Other bacteria with varying significance as fish pathogens were also identified including Plesiomonas shigelloides (25.0%), Chryseobacterium indoligenes (12.5%), Pseudomonas fluorescens (10.4%), Pseudomonas aeruginosa (4.2%), Pseudomonas stutzeri (2.1%), Vibrio cholerae (10.4%), Proteus spp. (6.3%), Citrobacter spp. (4.2%), Klebsiella spp. (4.2%) Serratia marcescens (4.2%), Burkholderia cepacia (2.1%), Comamonas testosteroni (8.3%) and Ralstonia picketti (2.1%). Aeromonas spp., Edwardsiella tarda and Streptococcus spp. were commonly isolated from diseased fish. Aeromonas spp. (n=82) and Plesiomonas shigelloides (n=73) were evaluated for antibiotic susceptibility. All isolates tested were susceptible to at-least ten (10) of the fourteen antibiotics evaluated. High levels of resistance were however expressed by all isolates to penicillin, oxacillin and ampicillin. This observed resistance is most probably intrinsic to those bacteria, suggesting minimal levels of acquired antibiotic resistance in fish bacteria from the study area. To our knowledge, this is the first study to establish the occurrence of several bacteria species infecting fish; and to determine antibiotic susceptibility of fish bacteria in Uganda. The current study provides baseline information for future reference and fish disease management in the country.
... Numerous wild stocks of anadromous salmon and trout (genus Oncorhynchus and Salmo) have experienced fluctuating abundance over the past century, with a series of sharp declines in abundance (16)(17)(18). As a consequence, conservation hatcheries have been flourishing, with the goal of preserving ecosystem integrity, enhancing declining populations, and sustaining fisheries. ...
Significance
Captive rearing is known to impact the fitness of individuals released in the wild, but the relative role of genetic vs. nongenetic underlying processes is still debated. We measured genome-wide methylation profiles to document epigenetic differences between Pacific salmon originating from a hatchery and their natural-born congeners in two geographically distant rivers. Our results provide evidence that the epigenetic modifications induced by hatchery rearing provide a potential explanatory mechanism for reduced fitness of hatchery-reared salmon once released in the wild.
... A number of countries have been dependent on capture fisheries as the major source of fish for decades. Despite the worldwide increase in fish production, a decline has been observed in several cases (Burkhardt-Holm et al. 2002;Noakes et al. 2000) and this has been majorly attributed to over-fishing and climate-related threats. For Uganda in particular, production dropped from about 0.5 million tons in the year 2007 to only 0.38 million tons in 2010 amidst several efforts by the government to increase production (MAAIF 2012). ...
... Interestingly, given the high degree of emphasis on problems associated with the marine survival of salmon, there are decidedly few stocks where both smolt and adult salmon are enumerated from which to monitor, and model trends in marine survival either from the northwest or -east Atlantic region. The potential impacts of escaped farmed salmonids on wild populations is another controversial area requiring additional research given the widespread concern raised in many areas (e.g., Hutchinson 1997;Noakes et al. 2000). ...
... Chinook salmon are native on the west coast of North America from the Berring Strait, south to Southern California. Population numbers of Chinook salmon have decreased substantially over the last century throughout its entire native range, mainly due to habitat destruction (Noakes et al. 2000;Crawford 2001). ...
... E-mail: cmmosser@ucdavis.edu overfishing, changes in ocean conditions, water quality and habitat degradation, genetic introgression with hatchery stocks, and impassable barriers to migration (Noakes et al. 2000;Lackey et al. 2006;Moyle et al. 2008). The loss of holding, spawning, and rearing habitat in California rivers and streams contributes substantially to the decline in provision of services provided by Chinook salmon ( Yoshiyama et al. 2001), largely related to the vast hydraulic manipulation of rivers in the Central Valley. ...
Spring-run Chinook salmon (Oncorhynchus tshawytscha) are particularly vulnerable to climate change because adults over-summer in freshwater streams before spawning in autumn. We examined streamflow and water temperature regimes that could lead to long-term reductions in spring-run Chinook salmon (SRCS) in a California stream and evaluated management adaptations to ameliorate these impacts. Bias-corrected and spatially downscaled climate data from six general circulation models and two emission scenarios for the period 2010-2099 were used as input to two linked models: a water evaluation and planning (WEAP) model to simulate weekly mean streamflow and water temperature in Butte Creek, California that were used as input to SALMOD, a spatially explicit and size/stage structured model of salmon population dynamics in freshwater systems. For all climate scenarios and model combinations, WEAP yielded lower summer base flows and higher water temperatures relative to historical conditions, while SALMOD yielded increased adult summer thermal mortality and population declines. Of management adaptations tested, only ceasing water diversion for power production from the summer holding reach resulted in cooler water temperatures, more adults surviving to spawn, and extended population survival time, albeit with a significant loss of power production. The most important conclusion of this work is that long-term survival of SRCS in Butte Creek is unlikely in the face of climate change and that simple changes to water operations are not likely to dramatically change vulnerability to extinction. DOI: 10.1061/(ASCE)WR.1943-5452.0000194. (C) 2012 American Society of Civil Engineers.
... Since the 1990s, significant declines have been observed for many populations of Pacific salmon (Noakes et al. 2000). These declines are of great concern because of the ecological, economic and cultural importance of Pacific salmon. ...
Understanding habitat requirements for spawning is important for species at risk of extirpation to define areas for protection of this critical life stage. Interior Fraser coho salmon (IFC) Oncorhynchus kisutch spawn in tributaries of the upper Fraser River, British Columbia, Canada. They are regionally isolated, genetically distinct, and have been listed as endangered. Recent enumeration efforts have shown declining escapement and range contraction. IFC spawn in snow-dominated watersheds, yet much of our understanding of spawner habitat requirements is based on information for coho from coastal rain-dominated systems. Consequently, we examined the relative influence of habitat features on spawning site selection. Our sampling focused on why fish chose particular locations and not others in what seemed to be suitable habitat. We defined several logistic regression models, including various combinations of physical, chemical and hydrological microhabitat features, and used an information-theoretic approach to evaluate the relative plausibility of these models. Models combining intragravel measures of electrical conductance, dissolved oxygen, temperature and specific discharge were the best models associated with spawning microhabitat selection, and jackknife validations showed that these models had good predictive abilities. Intragravel variables, therefore, appear to play a prominent role in spawning site selection for IFC. Understanding the influence of the intragravel environment on spawning site selection will help identify habitat requirements as well as potential threats to fish populations and will contribute to the development of comprehensive conservation initiatives.
The impacts fishing communities face as a result of declining fisheries productivity and access may largely hinge on measurable attributes of their social resilience. Wild-origin Pacific salmon populations have been in a marked decline since the 1960s, resulting in progressively declining access for many commercial fisheries. More recent acute stressors have caused appreciable tribulation to commercial fishers in British Columbia, raising concern over their capacity to remain viable in the industry, and underscoring the need to examine the fishery under a social resilience framework. Here, we coupled an online survey instrument with in-depth interviews to assess commercial salmon fishers’ social resilience, socioeconomic characteristics, risk perceptions, trust in fishery management, and the relationships between these variables. Our results show that social resilience is low overall, with older, more experienced, and less diversified fishers being particularly vulnerable to declining salmon access. While 73% of fishers reported having plans to adapt to future declines in salmon access, 92% reported feeling that there are barriers impeding their adaptation, and 75% reported having no trust in fisheries management helping them adapt. Fishers’ social resilience was positively correlated with their trust in, and perceived trust from fisheries management.
Healthy populations of salmonids are integral for the functioning of ecosystems and valuable for the socio-cultural well-being of humans. Past declines were attributed to anthropogenic stressors, raising concern about the sustainability of populations. Accordingly, many salmonids are listed on red lists and protected by national legislation. One region where salmonid populations are threatened is Northern Spain, the most southern distribution of both the Atlantic salmon (protected under the EU Habitat Directive) and the brown trout. Here, we collated ~ 700 biomonitoring samples of both species collected across 177 sites over a 10-year period (2010-2019) to describe ongoing trends in these species and to relate them to site characteristics and potential drivers. We showed that both species have declined substantially, with stocked individuals constituting the majority of both populations. Natural reproduction was almost entirely absent for the brown trout (< 1%), but present in the Atlantic salmon (~ 20%). Both species expressed distinct spatial patterns, likely related to their stocking. As such, the observed trends for both species illustrate that reproduction is almost entirely lacking, underlined by a lack of adult salmonids. As a result, we not only underline alarming conditions of both species, but also question the effectiveness of currently employed stocking. Given that both species are of increasing conservation concern, targeted restoration measures like dam removal and pollution reduction must be applied to generate self-sustaining populations. River basin speci c analyses of constraints are required to detect limiting factors on which conservation actions can be taken to ultimately make stocking dispensable.
As global salmon production accelerates in response to higher consumer demand for seafood, so does the need for sophisticated monitoring strategies to enable and maintain ethically sound, productive, and environmentally friendly production of fish. Innovative technologies are needed to ensure proper water quality, react to unfavorable hydrodynamic conditions, monitor for changes in fish health, and minimize ecological interactions with indigenous aquatic life, including fish escapes. Automated sensors connected wirelessly to data stations, visualization aids, and acoustic and physical tagging technologies are emerging tools capable of detecting environmental stress and its associated behavioral changes in farmed fish. Computer modeling of the monitoring data collected from a single salmon farm or collection of farms sharing a data network can be used to spot environmental trends vital for anticipating some of the consequences of climate change. Environmental regulations governing salmon farming in coastal areas are becoming more stringent in response to public pressures to protect coastal and ocean resources and to provide for multipurpose use of marine resources. As net-pen salmon aquaculture expands globally, new technologies will be essential to collect and interpret the anticipated larger volumes of data needed to meet these stringent regulatory requirements and to safeguard the high investment costs inherent in salmon farming. Integr Environ Assess Manag 2022;18:950–963. © SETAC
KEY POINTS
Innovative technologies are needed to ensure proper water quality, react to unfavorable hydrodynamic conditions, monitor for changes in fish health, and minimize ecological interactions with indigenous aquatic life. Automated sensors connected wirelessly to data stations, visualization aids, and acoustic and physical tagging technologies are emerging tools capable of detecting environmental stress and its associated behavioral changes in farmed fish. As net-pen salmon aquaculture expands globally, new technologies will be essential to collect and interpret the anticipated larger volumes of data needed.
Highlights
- First study to highlight parallel epigenetic modifications induced by hatchery rearing as a potential explanatory mechanism for rapid change in fitness
Summary
A puzzling question in conservation biology is how to maintain overall fitness of individuals bred in captive environment upon release into the wild, especially for rehabilitating declining or threatened species [1,2]. For salmonid species, a heritable change in fitness related traits and gene expression has been reported to occur in a single generation of captivity in hatchery environment [3–5]. Such rapid changes are congruent with models of inadvertent domestication selection which may lead to maladaptation in the natural environment [4]. Arguably, the underlying mechanism by which captivity may induce fitness difference between wild and captive congeners is still poorly understood. Short-term selection on complex phenotypic traits is expected to induce subtle changes in allele frequency over multiple loci [7–9]. Yet, most studies investigating the molecular basis for rapid change in fitness related traits occurring in hatchery have concentrated their effort on finding evidence for selection at the genome level by identifying loci with large effect.
Numerous wild stocks of Pacific anadromous salmon and trout (genus Oncorhynchus and Salmo ) have experienced fluctuating abundance over the past century, with a series of sharp declines [6–8]. With the objectives of preserving ecosystem integrity, enhancing declining populations and sustaining fisheries, conservation hatcheries have been flourishing. This is particularly true along the North American Pacific coast where billions of salmonids, all species included, are released each year. Despite substantial improvement of production management, the beneficial ecological role of hatcheries in enhancing and restoring wild stocks is still debated, mainly because of the reduced fitness and maladaptation of hatchery-fish when released in the wild [3,5,9]. Although previous studies showed that domestication selection was involved in such fitness impairment, they also observed that different environmental conditions (e.g. reduced fish density) significantly modulated the physiological acclimation to hatchery environment [4].
Environmental stimuli are especially relevant during early embryonic development, which also correspond to a sensitive methylation reprogramming window in vertebrates [10,11]. It is therefore plausible that differences in rearing environment during early development may result in epigenetic modifications that could in turn impact on fitness. However, the only epigenetic study to date pertaining to captive rearing in salmonids and performed using methylation-sensitive amplified fragments (MSAP) failed to identify significant changes in methylation profile associated with hatchery rearing [12]
Here, we used a higher resolution approach to compare the genome-wide pattern of methylation in hatchery-reared juvenile (smolt) Coho Salmon with that of their wild counterparts in two geographically distant rivers in British Columbia, Canada. Using a reduced representation bisulfite sequencing (RRBS) approach covering an average per individual of about 70 million cytosines in CpG context, we identified 100 methylated regions (DMRs) that differed in parallel between hatchery and natural origin salmon in both rivers. The total variance of epigenetic variation among individuals explained by river or origin and rearing environment in a RDA model was 16% (adj.R ² =0.16), and both variables equally explained about 8% of the variance after controlling for each other. The gene ontology analysis revealed that regions with different methylation levels between hatchery and natural origin salmon showed enrichment for ion homeostasis, synaptic and neuromuscular regulation, immune and stress response, and control of locomotion functions. We further identified 15,044 SNPs that allowed detection of significant differences between either rivers or sexes. However, no effect of rearing environment was observed, confirming that hatchery and natural origin fish of a given river belong to the same panmictic population, as expected based on the hatchery programs applied in these rivers (see Supplementary experimental procedures). Moreover, neither a standard genome-scan approach nor a polygenic statistical framework allowed detection of selective effects within a single generation between hatchery and natural origin salmon. Therefore, this is the first study to demonstrate that parallel epigenetic modifications induced by hatchery rearing during early development may represent a potential explanatory mechanism for rapid change in fitness-related traits previously reported in salmonids.
The estuarine salt marshes' role as habitat for fish has got attention of many people as it plays a vital role as fish breeding grounds. However, anthropogenic activities have changed the natural setting of many estuarine habitats. A good example is Washington Harbor where an introduction of the landscape pattern change as a result of human activities damaged the salmon habitat in the harbor. The changes to Washington Harbor brought about by the causeway resulted into habitat fragmentation and tidal disconnection. The causeway forms a physical barrier that restricts the movement of plants and animals. As a result majority of the adverse effects seen in this area are due to the loss of hydraulic connection and wave energy. Responding to this problem; design principles and technological methods for eco-habitat restoration were discussed in this paper. The habitat restoration design of rebuilding a bridge after removing the causeway and converts were analyzed and discussed. The experiences of habitat restoration and protection of Yangtze River estuary was useful as a case study. The paper recommended that historical data should be used to validate the main reason leading to habitat damage. On other hand, the ecosystem self-regulating ability is vital for ecosystem and thus it should be applied in the habitat restoration functions. Above all the restoration work, maintenance of the integrity and continuity offish habitat in the Yangtze River estuary is of necessity.
This paper analyses information on various macro environmental variables available since 1876 for the Southeast Pacific and more recent data on Jack mackerel Trachurus murphyi (Nichols, 1920) landings and biomass in the Peruvian sea, relating them to probable areas of water masses equivalent to Cold Coastal Waters (CCW) and Subtropical Surface Waters (SSW). It is concluded that the index of the Pacific Decadal Oscillation (PDO) presents expressions of variability that are consistent with those found for the Southern Oscillation Index (SOI) and that the detected changes in biomass of Jack mackerel T. murphyi in the Peruvian sea reflect changes in the availability of the fish stock associated with secular (SOI) and decadal (PDO) variability patterns. These fluctuations in stock availability impact fisheries in Ecuador, Peru and northern Chile, which show significant variations in their landings and would have given a biased picture of the state of abundance, leading to wrong diagnoses of the real situation of the exploited stocks. These patterns of variability would also affect the appearance of El Niño, making them start in the southern hemisphere autumn or spring depending on whether the current PDO is positive or negative. Periods of high (1876 - 1925 and 1976 - 2012) and low (1926 - 1975) variability are also identified in relation to the Euclidean distance of the variances of the SOI; and in relation to the PDO a distinction is made between warm (1925 - 1944 and 1975 - 1994), cold (1945 - 1974) and tempered or interface periods (1895 - 1924 and 1995 - 2012), the latter being explained by the interaction between periods of high variability.
The population of anadromous steelhead Oncorhynchus mykiss in the Keogh River has been studied intensively, in part because of its pattern of declining recruitment, which is largely attributed to poor marine survival. Climate variability has changed the productivity of salmonid species in all regions of the North Pacific, with areas alternately shifting between periods of enhanced and depressed productivity. The mechanisms governing marine survival and adult recruitment are central to contemporary resource management concerns but are also of concern with regard to the long‐term prospects of managing biodiversity. We provide evidence that postsmolt growth contributes to the pattern of marine survival of Keogh River steelhead over the period corresponding to smolt years 1977–1999. Size at ocean entry did not appear to have sufficient contrast to significantly affect survival. However, assessment of scale growth suggested that the fish's initial growth at sea is not as important as the sustained growth conditions during summer and fall of the postsmolt year. The return rate of steelhead was negatively correlated with sea surface temperature in the ocean domains that were assumed to provide postsmolt nursery habitat, suggesting that growth is directly affected by warming conditions or that ocean warming affects the food web upon which steelhead depend. Steelhead appear to respond to changing climate and growth regimes in a manner similar to that of their North Atlantic analog, the Atlantic Salmon Salmo salar . Comparative data show that eastern basin Atlantic Salmon populations are negatively affected by a thermal regime of increasing temperature during the postsmolt year, suggesting a relationship between postsmolt growth and survival.
Received August 14, 2013; accepted October 17, 2013
There was a synchronous and significant decrease in marine survival of coho salmon in the Strait of Georgia, Puget Sound, and off the coast from California to Washington after 1989. This large-scale, synchronous change indicates that trends in coho marine survivals were linked over the southern area of their distribution in the north-east Pacific, and that these linkages were associated with a common event. Indicators of large-scale climate change (the Aleutian Low Pressure Index) and of recent regional climate change (the April flows from the Fraser River) also changed abruptly about the same time. The synchrony of trends in marine survival of aggregates of coho stocks from three distinct marine areas and trends in climate indices implies that climate/ocean changes can have profound impacts on the population dynamics of coho salmon. The trend towards low marine survival may persist as long as the trends in the climate indicators do not change.
Since the climate regime shift of 1976-1977 in the North Pacific, the individual growth of Pacific halibut (Hippoglossus stenolepis) has decreased dramatically in Alaska but not in British Columbia. Recruitment has increased dramatically in both areas. The decrease in age-specific vulnerability to commercial longline gear resulted in a persistent underestimation of incoming recruitment by the age-structured assessment method (CAGEAN) that was used to assess the stock. This problem has been corrected by adding temporal trends in growth and fishery selectivity to the assessment model. The recent sustained high level of recruitment at high levels of spawning biomass has erased the previous appearance of strong density dependence in the stock-recruitment relationship and prompted a reduction in the target full-recruitment harvest rate from 30-35 to 20-25%. The climate regime shift affected a number of other stocks of vertebrates and invertebrates in the North Pacific. While the general oceanographic changes have now been identified, the specific biological mechanisms responsible for the observed changes have not.
Annual hatchery production rates of chinook (Oncorhynchus tshawytscha), coho (0. kisutch) , sockeye (0. nerka) , pink (0. gorbuscha) , chum (0. keta), masu (0. masu} salmon, and steelhead trout (0. mykiss} were obtained from published and unpublished sources and compiled as a computer database. Pacific Rim hatchery production trends for the 40-year period from 1950-1992 were analyzed for all species from four geographic areas: Pacific Northwest (Washington, Oregon, Idaho, and California), Canada (British Columbia), Alaska, and Japan (Honshu and Hokkaido). Production of chum, sockeye, and pink salmon has increased dramatically in Japan, Canada, and Alaska in the past 20 years. Chinook, coho, steelhead, and masu have also experienced moderate increases in the same time period; however, production of coho, chinook and steelhead has declined since 1985. Trends in survival of hatchery fish over the period 1970-90 are demonstrated where data were available. We noted that survival of coho salmon was greatest for releases into large estuaries, such as southeast Alaska, Georgia Strait, and Puget Sound, than into drainages discharging directly into the Eastern Pacific Ocean. A negative cline in survival of coho salmon was observed moving both north and south from the center of the distribution of the species in British Columbia. Survival trends for fall chinook released north of Puget Sound tended to be the opposite of those released to the south. Survival of Japanese chum salmon released into the North Pacific Ocean has increased steadily from the mid-1960's to the present.
Cultured Atlantic salmon (Salmo salar L.) may be introduced into natural systems intentionally or accidentally. As smolts or post-smolts, they move to the feeding areas of wild salmon in the North Atlantic Ocean. As maturing fish, they return to the area of release and enter rivers to spawn. Lack of juvenile river experience is the prime reason why cultured salmon often enter fresh water later in the season than wild fish. During spawning, cultured female salmon from fish farms make fewer nests, tend to breed for a shorter period of time, are poorer at nest covering, and retain greater amounts of unspawned eggs than wild females. Cultured male salmon from fish farms exhibit less combat and display behaviour, have greater difficulty in acquiring access to mates, show less quivering and courting behaviour, and have lower reproductive success than wild males. However, cultured male salmon are more involved in prolonged, reciprocal fights than wild males and are, therefore, more often wounded. The reproductive success of cultured salmon increases with the time the fish have lived in nature before maturing sexually; for cultured females released in nature at the smolt stage, reproductive success is similar to that of wild females. The relative reproductive success of cultured males is smaller than that of corresponding females. Within both sexes of cultured and wild salmon, competitive spawning ability increases with body size. As a phenotypic response to increased growth rate during the first year of life, cultured salmon tend to have smaller sized but more numerous eggs than wild fish of the same size. Offspring of cultured salmon are more generally aggressive, more risk prone, and have a higher growth rate than wild offspring. Consequently, their survival rate in nature may be lower.
Biochemical genetic variation was used to determine the proportions of progeny sired by individual male chinook salmon (Oncorhynchus tshawytscha) in crosses derived from multiple male parents. For crosses conducted with mixtures of semen, an equal volume of semen from each of three males was pooled and used to fertilize the eggs of an individual female immediately after pooling, and after holding the pooled semen for 15 and 60 min before use. Male potency varied in these crosses, with individual males siring between 5 and 88% of the progeny of a cross. Potency differences among males were reduced with the use of pooled semen that had been held for 60 min prior to fertilization. For crosses derived from the sequential addition of semen, semen from three males was added at 45-s intervals to the eggs of a single female. In these crosses, individual males sired between 0 and 94% of the progeny of a single cross. The position occupied by a male in the fertilization sequence was a significant factor in determining the proportion of progeny that he sired, but differences in male potency were also observed.
Large fluctuations in the trends of Pacific salmon production in this century have been linked to trends in climate in the Pacific that are in turn associated with climate trends throughout the Northern Hemisphere. The close correspondence in the persistence of climate trends and the synchrony of the changes is evidence that a common event may cause the regime shifts. The trends or regimes can be characterized by stable means in physical data series or multiyear periods of linked recruitment patterns in fish populations. The regime concept is important in fisheries management because the natural shifts in abundance may be large and sudden, requiring that these natural impacts be distinguished from fishing effects. An equally important consideration is that biological and physical mechanisms may change when regimes shift, resulting in conditions that may not be characterized in the earlier part of the data series. Fluctuations in Pacific salmon abundance in this century were synchronous with large fluctuations in Japanese sardine abundance, which can be traced back to the early 1600's. The synchrony in the fluctuations suggests that Pacific salmon abundance may have fluctuated for centuries in response to trends in climate. The concept of regimes and regime shifts stresses the need to improve our understanding of the mechanisms that regulate the dynamics of fish and their ecosystems.
The abundance of Fraser River sockeye salmon (Oncorhynchus nerka) stocks was low in the 1960s, increased to high levels in the 1980s, and possibly entered a period of low abundance in recent years. The abundance changes of the combined stocks can be separated into productivity regimes that correspond to changes in climate trends. The most distinct change occurred when there was a major change in the climate over the Pacific Ocean in the winter of 1976-1977. The existence of natural shifts in abundance trends means that the high returns that occur during periods of high productivity would not be expected to occur during the low-productivity periods. The response of Fraser River sockeye to climate changes may be a specific example of a more general response by a number of species of fishes in the Pacific and perhaps in other oceans. Because the shift from one regime to the other occurred quickly in the 1970s, future shifts could also occur quickly. It is necessary to detect natural shifts in productivity when attempting to manage fishing impacts to ensure that economic expectations are sound and that overfishing does not occur.
The chinook salmon DNA probe B2-2 was used to distinguish farm-reared (from two commercial farms) and native chinook salmon (Oncorhynchus tshawytscha) that were sampled from five populations on the west coast of Vancouver island. The Big Qualicum River population (east coast of Vancouver Island), which is believed to be the main progenitor of domesticated broodstocks used for aquaculture in British Columbia, was also sampled. The presence or absence and integrated optical densities (IODs) of three DNA fragments at 8.3 kilo base pairs (kbp) (band 1), 6.5 kbp (band 2), and 5.6 kbp (band 3) in the hybridization patterns of B2-2 on BamHI-restricted DNA were recorded for 269 chinook salmon. The frequency of occurrence of bands 2 and 3, and all seven measurements made of the relative and absolute values of the IODs of the three bands, varied significantly among populations. The IOD of band 3 provided the best discrimination among populations. The Big Qualicum and two fish farm populations were differentiated from all five west coast native populations. Discriminant analysis and a neural network were used independently to classify correctly to type an average of 97% of the native and 83% of the farm west coast DNA patterns used as test samples.
Alaskan salmon stocks have exhibited enormous fluctuations in production during the 20th
century. In this paper, we investigate our hypothesis that large-scale salmon-production variability is
driven by climatic processes in the Northeast Pacific Ocean. Using a time-series analytical technique
known as intervention analysis, we demonstrate that Alaskan salmonids alternate between high and low
production regimes. The transition from a high(low) regime to a low(high) regime is called an
intervention. To test for interventions, we first fitted the salmon time series to univariate autoregressive
integrated moving average (ARIMA) models. On the basis of tentatively identified climatic regime shifts,
potential interventions were then identified and incorporated into the models, and the resulting fit was
compared with the non-intervention models. A highly significant positive step intervention in the late
1970s and a significant negative step intervention in the late 1940s were identified in the four major
Alaska salmon stocks analyzed. We review the evidence for synchronous climatic regime shifts in the late
1940s and late 1970s that coincide with the shifts in salmon production. Potential mechanisms linking
North Pacific climatic processes to salmon production are identified.
Since the climate regime shift of 1976-1977 in the North Pacific, the individual growth of Pacific halibut (Hippoglossus stenolepis) has decreased dramatically in Alaska but not in British Columbia. Recruitment has increased dramatically in both areas. The decrease in age-specific vulnerability to commercial longline gear resulted in a persistent underestimation of incoming recruitment by the age-structured assessment method (CAGEAN) that was used to assess the stock. This problem has been corrected by adding temporal trends in growth and fishery selectivity to the assessment model. The recent sustained high level of recruitment at high levels of spawning biomass has erased the previous appearance of strong density dependence in the stock-recruitment relationship and prompted a reduction in the target full-recruitment harvest rate from 30-35 to 20-25%. The climate regime shift affected a number of other stocks of vertebrates and invertebrates in the North Pacific. While the general oceanographic changes have now been identified, the specific biological mechanisms responsible for the observed changes have not.
This paper addresses the genetic consequences of aquaculture on natural fish populations. The study is motivated by rapidly increasing numbers of intentionally and accidentally released fish and is based on empirical observations reported in the literature. A wide variety of outcomes, ranging from no detectable effect to complete introgression or displacement, has been observed following releases of cultured fish into natural settings. Where genetic effects on performance traits have been documented, they always appear to be negative in comparison with the unaffected native populations. These findings are consistent with theoretical considerations of the implications of elevated levels of gene flow between cultured and locally adapted natural populations; they raise concerns over the genetic future of many natural populations in the light of increasing numbers of released fish. Strategies for the genetic protection of native populations from the effects of aquaculture are outlined including more secure containment, the use of sterilized fish, and modifying the points of rearing and release. We recommend strong restrictions on gene flow from cultured to wild populations and effective monitoring of such gene flow.
Tube dilution MIC and MBC assays were used to estimate the influence of Mg++ (54 mM) Ca++ (10 mM) and 25% (w/v) marine sediment on the biological activity of oxytetracycline hydrochloride against Listonella anguillarum. Assays were performed at 22°C in phosphate-free tryptone media. MIC data indicated that, in the presence of Mg++ and Ca++, the bioactivity was 12.5 %, in the presence of sediment it was 1.5 % and when both were present it was <0.4%. Equivalent figures derived from MBC data were 6 %, < 0.4 % and < 0.4 % respectively. Concentrations in excess of 800 μg / ml oxytetracycline were required to kill the test bacteria in the presence of sediment compared to the 3 μg / ml required to have the same effect in the basic medium.
Deleterious genetic change in wild anadromous salmonids (Oncorhynchus spp.) is expected from fisheries differentially harvesting fish that spawn at particular times within a season, mature at particular sizes or ages, or grow at particular rates. Other sources include overfishing, habitat degradation or destruction, and interactions with hatchery fish, particularly when these phenomena severely reduce population size. Gene flow from hatchery to wild fish populations also is deleterious because hatchery populations genetically adapt to the unnatural conditions of the hatchery environment at the expense of adaptation for living in natural streams. This domestication is significant even in the first generation of hatchery rearing. Spawner-recruit theory serves as a framework for discussing the consequences of deleterious genetic change. This theory can illustrate how the fitness or productivity of a population is reduced and whether genetic change is largely offset by natural selection within one generation, or accumulates over many generations. Although our knowledge is far from complete, sufficient information exists to demand actions to reduce or avoid deleterious genetic change. As additional information becomes available, these actions may be changed, perhaps relaxed. One suggested action is to establish or maintain “refuge” populations of wild fish that are to be protected from habitat degradation, selective or intense fishing, and interactions with hatchery fish.
The genetic response of Atlantic salmon to culture is important in predicting the success of these fish in nature and their
impacts on wild populations through competition and interbreeding. We compared a seventh-generation strain of farmed Atlantic
salmon from Sunndalsøra, Norway, with its principal founder population from the wild, the River Namsen. The fish were reared
from eggs in a common environment and assessed for the extent of genetic divergence in several fitness-related traits. Morphology
had diverged, as farmed juveniles showed more robust bodies and smaller rayed fins than the wild juveniles. Ecologically important
aspects of behaviour also differed. Farmed juveniles were more aggressive in a tank environment typical of culture facilities,
while wild juveniles dominated in a stream-like environment. Farmed juveniles were also more risk-prone, reappearing from
cover sooner after a simulated predator attack. It was not surprising that growth performance was higher in farmed than wild
juveniles, as the former had been subjected to intentional selection for this trait. Correlated responses to this selection
may also explain the higher rate of smolting and lower rate of male parr maturity in the farmed than the wild salmon. Competition
with wild juveniles, however, negatively affected the growth of the farmed juveniles, particularly under semi-natural conditions.
Our results indicate that farming of Atlantic salmon generates rapid genetic change, as a result of both intentional and unintentional
selection in culture, that alters important fitness-related traits.
Atlantic salmon (Salmo salar L.) escapees from commercial salmon farms in Washington State, USA, and British Columbia, Canada, arecaught in fisheries
from Washington State to Alaska. A large escape from a farm near Cypress Island, Washington, was likely to have been the cause
of increased abundance of Atlantic salmon in Juan de Fuca Strait and higher than average catches on the west coast of Vancouver
Island during the summer of 1996. The catch of Atlantic salmon in Alaska in 1996 exceeded the sum of catches in all previous
years. The number of escapees recorded in fresh water has been increasing, with more than 210 adult fish observed in 29 rivers
in British Columbia during 1996. During the winter of 1995/1996, 39 Atlantic salmon were reported caught in the Salmon River
on Vancouver Island. Analysis of the stomach contents of these fish indicated that some were feeding in fresh water.
Oxytetracycline (OT) is used extensively in the treatment of bacterial diseases in marine f ~ s h . The standard dose recommended for treatment of fish is 5 to 10 times higher than doses commonly used in medical practice, indicating that OT is poorly absorbed. This is especially true for fish held in sea water, where the intestinal uptake is substantially reduced as compared to fish in fresh water. OT forms complexes with magnesium and calc~um We have determined the con~plex constants and calculated that when therapeutic concentrations of OT are present in sea water, only about 5 O/O of the OT exists in the free form. Of the bound OT, the 1:l OT-magnesium complex predominates. The complex formation in sea water results in a strong reduction in the antibacterial effect of OT This has been demonstrated in vitro. The poor intestinal uptake and reduced antibacterial effect of complex-bound OT is caused by an alteration of the molecular charge that diminishes its ability to cross lipid-rich biological membranes. A major portion of the OT administered to farmed salmonids inevitably ends up in the environment, especially in the sediments under aquaculture facilities. No mechanism is known for biodegradation of OT and thus it can remain in the sediments long enough to affect the indigenous bacterial flora and induce resistance. For these reasons the use of OT in marine environments should be questioned.
Pacific salmon have been fished extensively for at least a century and artificial production of Pacific salmon has been a management strategy to improve production for almost as long. Hatchery production is considered important because it is commonly believed that the carrying capacity for salmon in the ocean has remained more or less constant and is underutilized as a consequence of limited production of smolts in fresh water. Since the mid-1960s, there has been an increase in hatchery production, partly as a response to a desire to increase catch and partly because of improved hatchery techniques. Since the late 1970s there has been a dramatic increase in the total Pacific salmon catch. The increases in catch are now known to result from a large-scale shift in the productivity of the sub-arctic Pacific and management and enhancement actions. Environmental indices changed about 1989-1990 and may indicate that the productive regime of the 1980s has ended. This would imply that under natural conditions Pacific salmon abundance would decline. There are no clear indications of what to expect in the new regime, but it is apparent that the massive production of artificially reared Pacific salmon would not be necessary in a less productive regime. Of concern is the impact that the large numbers of artificially reared salmon will have on wild salmon stock levels.
A survey of wild fishes captured around marine net-pen salmon farms and from open waters for certain salmonid pathogens was conducted in the coastal waters of British Columbia. Viral hemorrhagic septicemia virus was detected in Pacific herring Clupea pallasi, shiner perch Cymatogaster aggregata, and threespine sticklebacks Gasterosteus aculeatus. Infectious hematopoietic necrosis (IHN) virus was detected in one Pacific herring (collected well away from the farms) and in tube-snouts Aulorhynchus flavidus and shiner perch collected from a farm experiencing an IHN outbreak. Renibacterium salmoninarum was observed in moribund Pacific hakes Merluccius productus collected from within a net-pen and was also detected in several ocean-caught salmon. Aeromonas salmonicida subsp. salmonicida (typical strain) was isolated from a juvenile chinook salmon Oncorhynchus tshawytscha, whereas the atypical strain of this organism was isolated from a lingcod Ophiodon elongatus. Loma salmonae (Microsporea) was observed in chinook salmon, chum salmon Oncorhynchus keta, coho salmon O. kisutch, sockeye salmon O. nerka, and pink salmon O. gorbuscha, all of which were captured well away from net-pens. Loma spp. (Microsporea) were observed in the gills of shiner perch, lingcod, Pacific tomcod Microgadus proximus, Pacific cod Gadus macrocephalus, walleye pollock Theragra chalcogramma, and sablefish Anoplopoma fimbria; all but the first species represent new hosts for Loma. Epitheliocystis, caused by a chlamydia-like organism, was detected in the gills of chinook salmon, chum salmon, coho salmon, pink salmon, lingcod, Pacific cod, Pacific hakes, Pacific tomcod, walleye pollock, sablefish, shiner perch, Dover soles Microstomus pacificus, Pacific sanddabs Citharichthys sordidus, and various species of rockfish Sebastes spp., most of which represent new host records for this infection.
Today, over 94% of all adult Atlantic salmon (Salmo salar) are in the aquaculture niche and wild numbers continue to decline while aquaculture numbers increase. The developmental and evolutionary forces in the aquaculture or "domestic" niche are so unlike those in the wild niche that two distinct biologies are being created from the original Atlantic salmon species. We may now need to recognize a new biological entity-Salmo domesticus-and treat it as an "exotic" when it escapes into the wild. Escapement therefore raises important concerns about ecological and genetic impacts, both within and outside the native range of Salmo salar. This paper explains why escaped domestic Atlantic salmon have had an impact on wild Atlantic salmon populations and now threaten Pacific salmonids as well. A polarization of views between aquaculturists and environmentalists will not resolve the problems. The three interest groups in fisheries-aquaculture, biodiversity, and capture-must begin to work together if we are to take up the challenge of preserving biodiversity and if aquaculturists, who hold the future of Atlantic salmon in their hands, can be expected to willingly prevent further impacts from their industry.
The practical difficulties in measuring the prevalence, incidence, and pathogenicity of diseases in wild Atlantic salmon populations cause serious problems in determining the possible implications of disease. Limited research has been undertaken on wild salmon disease associated with environmental effects of fish farming, or with the disease implications of possible changes to the genetic make-up of wild salmonid stocks as a consequence of farmed fish escaping. To date, no significant disease problems have been reported linked to these aspects. The greatest disease risk to both farmed and wild stocks is through the introduction of exotic pathogens into areas where local stocks have no innate resistance. National and international legislative controls are in existence to reduce this risk, but these have not afforded total protection. Serious epizootics of furunculosis and Gyrodacfylus saluris in stocks of salmon indicate the severe consequences of new disease outbreaks linked to movements of live fish for farming or restocking purposes. A wide mnge of infectious agents has been recorded from wild salmon and some of these (and from other species of wild fish) provide the primary source of infection leading to disease problems in fish farms. Although disease control has markedly improved in fish farms in recent years, problems still remain with some diseases, notably sea lice. It is likely that the lice population and other diseases in farms contribute infection to local wild stocks, but the extent and consequences of this have not been quantified. 0 British Crown copyright 1997
Protection from communicable diseases of salmonid fishes is an important component of fisheries management strategy; experiences in Canada over the past two decades are presented. A comprehensive range of measures was developed to protect the health of salmon and trout resources by minimizing the risk of introducing and disseminating communicable diseases. These measures affect both wild resources and aquaculturc operations. They include national regulations. provincial and regional fish health protection initiatives, and control of potential hazards related to use of live fish for research, manufacture of feeds, importation and production of biologics, and use of drugs and therapeutics. A strengthened research and development capability supported technological innovation and provided the basis for refining regulations and policies. Programs for training and skill development in the prevention, control, and treatment of fish diseases were also expanded. This integrated strategy created a favorable climate for major investments in salmonid farming and its allied industries. It was considered effective in preventing the introduction of some pathogens as yet unrecorded in Canada and in confining pathogens known to occur in Canada within limited geographic distributions. As our understanding of fish pathogens and the diseases they cause continues to build, we expect to focus more in the future on continental concerns, continued refinement of legislation and compliance protocols, and rapid adoption of new technologies.
The abundance of Fraser River sockeye salmon (Oncorhynchus nerka) stocks was low in the 1960s, increased to high levels in the 1980s, and possibly entered a period of low abundance in recent years. The abundance changes of the combined stocks can be separated into productivity regimes that correspond to changes in climate trends. The most distinct change occurred when there was a major change in the climate over the Pacific Ocean in the winter of 1976-1977. The existence of natural shifts in abundance trends means that the high returns that occur during periods of high productivity would not be expected to occur during the low-productivity periods. The response of Fraser River sockeye to climate changes may be a specific example of a more general response by a number of species of fishes in the Pacific and perhaps in other oceans. Because the shift from one regime to the other occurred quickly in the 1970s, future shifts could also occur quickly. It is necessary to detect natural shifts in productivity when attempting to manage fishing impacts to ensure that economic expectations are sound and that overfishing does not occur.
The fertilization rate or ‘potency’ of milt from individual male chinook salmon (Oncorhynchus tshawytscha) used to fertilize eggs in pooled milt mixtures was examined. Electrophoresis was used to identify four sets of three males each in which each male would produce genetically distinct progeny. In control crosses, milt from each male was applied individually to eggs to determine male fertility. In experimental crosses, an equal volume of milt from each of three males was pooled and applied to eggs to determine male potency.In the crosses made with pooled milt, individual males fertilized between 1.4% and 75.6% of the eggs. There was significant heterogeneity between replicate crosses that utilized milt pooled from the same three males. The potency of an individual male was not correlated with his fertility in control crosses nor with his spermatocrit value, and varied depending on which other males contributed to the milt mixture. The implications of these findings for loss of genetic variability in hatchery populations of salmonids is discussed.
The results of artificial crossbreeding of Salmo salar and Oncorhynchus gorbuscha of the Kola river (Murmansk region) are discussed. Observations are presented on developmental characteristics of the hybrid and the Atlantic salmon parent, as well as karyological data on hybrid and control embryos.Crosses of Atlantic salmon and pink salmon of the Kola river produced non-viable embryos with various morphological anomalies. The diploid chromotype of the hybrid ranged from 52 to 56. The number of two-armed chromosomes in the karyotype of the hybrid embryos was greater than that in the karyotype of Atlantic salmon. It is concluded that crosses of Atlantic salmon and pink salmon could not occur in nature.
From 1976 to 1978 there was a change in the climate over the North Pacific Ocean. The Aleutian Low intensified and there was a warming of the sea surface adjacent to North America and a cooling offshore. Associated with this change was a period of exceptional fish production. Strong year classes and above-average survival occurred for many commercially important species all along the west coast of Canada and the United States. Trends in total salmon catches increased primarily from increased salmon production in Alaska. Some stocks of maturing pink (Oncorhynchus gorbuscha), coho (O. kisutch), and chinook salmon (O. tshawytscha) also had above-average growth in 1977. A majority of commercially important nonsalmon species that spawned from California to the Bering Sea and have a wide range of life history types also had exceptionally strong year classes from 1976 to 1978. The exceptional survival appears to be related to improved ocean productivity caused by changes in the intensity of the Aleutian Low.
Pink (Oncorhynchus gorbuscha), chum (O. keta), and sockeye salmon (O. nerka) represent approximately 90% of the commercial catch of Pacific salmon taken each year by Canada, Japan, the United States, and Russia. Annual all-nation catches of the three species and of each species, from 1925 to 1989, exhibited long-term parallel trends. National catches, in most cases, exhibited similar but weaker trends. The strong similarity of the pattern of the all-nation pink, chum, and sockeye salmon catches suggests that common events over a vast area affect the production of salmon in the North Pacific Ocean. The climate over the northern North Pacific Ocean is dominated in the winter and spring by the Aleutian Low pressure system. The long-term pattern of the Aleutian Low pressure system corresponded to the trends in salmon catch, to copepod production, and to other climate indices, indicating that climate and the marine environment may play an important role in salmon production.
Time scales, and the trophic relations between these scales, are very different in the sea from those on land. In particular, marine systems are much more responsive to decadal scale alterations in their physical environment but are also much more adaptable. Thus it is difficult, and probably counterproductive, to try to define a baseline state for marine ecosystems. Further, regime shifts in fish communities can have major economic consequences without being ecological disasters. Climatic changes at decadal scales, from natural or anthropogenic causes, are likely to produce or enhance regime shifts. There are different management issues in different sectors. The coastal zone demands our intervention to assure integrated management of the land and sea components. At the other extreme, our understanding of open ocean systems is an essential element of climate prediction and so of eventual management. Between these two environments, our use of resources in continental shelf seas requires an ability to distinguish between human and natural causes of long-term change.