In presenting this thesis in partial fulfilment of the requirements for an advanced degree at the... more In presenting this thesis in partial fulfilment of the requirements for an advanced degree at the University of British Columbia, I agree that the Library shall make it freely available for reference and study. I further agree that permission for extensive copying of this thesis for scholarly purposes may be granted by the head of my department or by his or her representatives. It is understood that copying or publication of this thesis for financial gain shall not be allowed without my written permission.
Commercial salmon harvests have declined dramatically for all Pacific salmon species in British C... more Commercial salmon harvests have declined dramatically for all Pacific salmon species in British Columbia, mainly over the period 1995-2000. Much of this decline is attributable to declining abundance, but some of it has been due to deliberate reduction in allowable exploitation rates. Various reasons have been given for this reduction, but the main rationale appears to have been concern about declines in a few relatively small and unproductive stocks that are intercepted in mixed-stock fisheries. Reductions in exploitation rate have generally not been followed by the increases in stock size that would be expected if overfishing had been the main cause of the declines. Current procedures for setting exploitation rate goals do not appear to involve explicit analysis of the risk-reward trade off relationship between mixed stock exploitation rates and yields.
Transactions of The American Fisheries Society, Apr 27, 2017
Details of the spatial ecology of White Sturgeon Acipenser transmontanus in the lower Fraser Rive... more Details of the spatial ecology of White Sturgeon Acipenser transmontanus in the lower Fraser River, British Columbia, are needed for habitat conservation, assessments of impacts from spatially delimited threats, and refinement of abundance estimation methods. The abundance of threatened lower Fraser River White Sturgeon is assessed annually using a Bayesian, closed-population, mark-recapture model. If individuals make prolonged departures from the lower Fraser River, either into marine waters or a tributary, the validity of the model's assumed closed population is questionable. There is also concern that fish might move far enough to be exposed to harvest in Puget Sound, Washington. From 2008 to 2012, White Sturgeon of various sizes were acoustically tagged in the Pitt River (n = 58) and in the lower reaches of the Fraser River (near Douglas Island, n = 52) to determine the timing, rate, and spatial extent of movements. Movements were monitored using acoustic receivers at 17 locations in the lowermost 92 km of the main-stem Fraser River, three in the first 21 km of the Pitt River (a tributary to the lower Fraser River), and nine in the coastal waters of British Columbia and Washington State. Travel speeds showed a strong skew toward slower movements (74% were <1 km/h) and did not differ significantly between upstream and downstream directions. On average, 33.2% of the sample was mobile (displacing~13.4 km/month) and 66.8% was sedentary (displacing~1.87 km/month). In general, White Sturgeon were significantly more sedentary during winter months and more mobile during spring and fall. Annual or seasonal migratory movements and patterns were observed for 73% of fish tracked. Repeated use of specific locations within the lower Pitt River during midwinter suggested White Sturgeon have a high fidelity for specific overwintering sites. Several of the tagged fish showed annual movements to the lowest reaches of the Fraser River for 1-3 months between May and September, although there was no direct evidence that they left the Fraser River and entered the Strait of Georgia. By contrast, there was strong evidence for extended and repeated movement into the lower Pitt River. Given that the lower Pitt River is outside the mark-recapture assessment area, our results suggest either that the area's boundaries need expansion, or alternative models should be considered for abundance estimations of lower Fraser River White Sturgeon. White Sturgeon Acipenser transmontanus are endemic to the west coast of North America, and known spawning locations occur in the Sacramento, Columbia, and Fraser rivers (McPhail 2007). Some White Sturgeon populations are anadromous (Schaffter 1997), and others live primarily in freshwater but with known marine tolerance (Veinott et al. 1999; Welch et al. 2006). In Canada, White Sturgeon are of cultural and economic importance. The species has been important to aboriginals for generations (Nelson et al. 2013b), actively targeted by anglers (Inglis and Rosenau 1994), and at one time was commercially exploited (Semakula and Larkin 1968), although overfishing caused the fishery to collapse at the turn of the last century (Echols and FRAP 1995; Ptolemy and Vennesland 2003). White Sturgeon are long-lived, latematuring fish (Semakula and Larkin 1968); thus it is not surprising that populations have been slow to recover from
There is extensive evidence that fishing is often selective for specific phenotypic characteristi... more There is extensive evidence that fishing is often selective for specific phenotypic characteristics, and that selective harvest can thus result in genotypic change. To date, however, there are no studies that evaluate whether fishing is selective for certain physiological or energetic characteristics that may influence fish behaviour and thus vulnerability to capture. Here, adult sockeye salmon (Oncorhynchus nerka) were used as a model to test the null hypothesis that fishing is not selective for specific physiological or energetic traits. Fish were intercepted during their spawning migrations, implanted with a gastric radio transmitter, and biopsied (i.e., non-lethally sampled for blood, gill tissue and quantification of energetic status). In both 2003 and 2006, we tagged and biopsied 301 and 770 sockeye salmon, respectively, in the marine environment en route to their natal river system to spawn. In 2006 an additional 378 individuals were tagged and biopsied in freshwater. We found that 23 (7.6%) of the marine fish tagged in 2003, 78 (10.1%) of the marine fish tagged in 2006 and 57 (15.1%) of the freshwater fish tagged in 2006 were harvested by one of three fisheries sectors that operate in the coastal marine environment and the Fraser River (i.e. commercial, recreational or First Nations fisheries between the site of release and Hell's Gate in the Fraser River, approximately 250 km upriver and 465 km from the ocean tagging site). However, fisheries were not open continually or consistently in different locations and for different fisheries sectors necessitating a paired analytical approach. As such, for statistical analyses we paired individual fish that were harvested with another fish of the same genetic stock that was released on the same date and exhibited similar migration behaviour, except that they successfully evaded capture and reached natal spawning grounds. Using two-tailed Wilcoxon matched pairs signed-rank tests, we revealed that the physiological and energetic characteristics of harvested fish did not differ from those of the successful migrants despite evaluating a number of biochemical (e.g. plasma metabolites, cortisol, plasma ions, gill Na + /K +-ATPase) and energetic (e.g. gross somatic energy density) variables (P's all >0.10). However, for some analyses we suffered low statistical power and the study design had several shortcomings that could have made detection of differences difficult. We suggest that additional research explore the concept of fishing-induced selection for physiological characteristics Evolutionary Applications
Canadian Journal of Fisheries and Aquatic Sciences, Mar 1, 1983
Juvenile chinook salmon, Oncorhynchus tshawytscha, were raised in 90-m3 mesh enclosures in Saanic... more Juvenile chinook salmon, Oncorhynchus tshawytscha, were raised in 90-m3 mesh enclosures in Saanich Inlet, B.C. The enclosures permitted ample water and zooplankton circulation while retaining 5–6 g juvenile salmon. Mean growth rate was 1.8% wet body weight/d over 6 wk. Weekly growth rates ranged from 3.9%/d while food was abundant, to −0.5%/d when food was scarce. Zooplankton concentration inside and outside enclosures without fish were not significantly different. Organisms associated with the sides of the enclosures (non-pelagic) were not a major contributor to the growth of the juvenile chinook. There was a strong relationship between the fish growth rates and the abundance of 1.4- to 4.5-mm zooplankton. Rates of successful search varied directly with the size and inherent contrast of a prey item. The minimum rate of successful search was 2.3 m3/h for salmon feeding on 1.4- to 4.5-mm zooplankton. This rate of successful search, while far greater than previously suspected, is still within the visual capabilities of the juvenile salmon. The enclosed salmon grew rapidly on zooplankton concentrations that were 1/1000 of those required to sustain similar growth rates in tank experiments.Key words: predator–prey relationship, planktivorous salmonid, marine, &amp;amp;amp;amp;amp;amp;quot;in situ&amp;amp;amp;amp;amp;amp;quot; enclosures, search efficiency
Canadian Journal of Fisheries and Aquatic Sciences, Jul 1, 2006
Beginning in 1995, segments of the late-run sockeye salmon (Oncorhynchus nerka) stocks from the F... more Beginning in 1995, segments of the late-run sockeye salmon (Oncorhynchus nerka) stocks from the Fraser River, British Columbia, have initiated upriver spawning migration up to 6 weeks earlier than historical records; and those fish have experienced high rates of en route mortality. We examined the correlations between physiological and energetic status prior to river entry with subsequent migratory performance of individual salmon using telemetry and noninvasive biopsies for Adams-Thompson-Shuswap (Adams) and Weaver-Harrison (W-H) stocks. Salmon that failed to reach the river were characterized by a tendency to have elevated levels of chronic and acute stress indicators. For one stock of fish (i.e., Adams) that entered the river, those that died before reaching spawning grounds were individuals with low gross somatic energy. Furthermore, females tended to have elevated plasma estradiol levels. When contrasting fish with different behaviours and fates, fish that did not hold in the estuary and subsequently died tended to have less energy than fish that held and reached spawning areas. Females from the former group also had higher 11ketotestosterone and estradiol levels relative to those from the later group. These data suggest that differences in physiological and energetic status may be associated with high en route mortality in late-run sockeye salmon. Résumé : Depuis 1995, des portions des stocks à migration tardive de saumons rouges (Oncorhynchus nerka) du Fraser, Colombie-Britannique, commencent leur migration de reproduction vers l'amont jusqu'à six semaines avant la période normale du passé et elles subissent de forts taux de mortalité durant le trajet. Nous examinons les corrélations entre les statuts physiologique et énergétique avant l'entrée en rivière et la performance subséquente de la migration chez des saumons individuels des stocks Adams-Thompson-Shuswap (Adams) et Weaver-Harrison (W-H) à l'aide de la télémétrie et de biopsies non invasives. Les saumons qui n'atteignent pas la rivière ont tendance à avoir des niveaux élevés d'indicateurs de stress chronique et aigu. Chez l'un des stocks (c.-à-d., Adams) qui a pénétré dans la rivière, les poissons qui sont morts avant d'atteindre les sites de fraye étaient des individus possédant une faible énergie somatique brute. De plus, les femelles avaient tendance à avoir des concentrations plasmatiques élevées d'oestradiol. En comparant des poissons ayant des comportements et des sorts différents, nous trouvons que les poissons qui ne se sont pas maintenus dans l'estuaire et qui sont morts subséquemment avaient tendance à avoir moins d'énergie que les poissons qui se sont maintenus et qui ont atteint les sites de fraye; les femelles du premier groupe avaient aussi des concentrations plus élevées de 11-céto-testostérone et d'oestradiol que celles du second groupe. Ces données indiquent que les statuts physiologique et énergétique peuvent être associés à une forte mortalité durant le trajet chez le saumon rouge. [Traduit par la Rédaction] Cooke et al. 1480
Few studies have examined the effects of fisheries capture on wild fish, particularly in the cont... more Few studies have examined the effects of fisheries capture on wild fish, particularly in the context of evaluating the sustainability of capture and release methods for Pacific salmon (Oncorhynchus spp.) during upriver migration. This study examined the physiological condition, post-release behaviour and survival of adult migrating sockeye salmon (O. nerka) in the Fraser River, British Columbia, Canada. Fish were captured by either beach seine or angling and released immediately, or were captured by angling and released following a 24-h recovery period in a net pen. Before release, all salmon were biopsied or tagged with radio telemetry transmitters. Capture by either angling or beach seine with immediate release resulted in >95% survival 24 h after release, whereas net pen recovery after angling resulted in ∼80% survival. This differential in survival was similarly expressed in the percentage of released fish reaching natal sub-watersheds, with 52.2% and 36.3% of fish immediately released by beach seine and angling reaching natal sub-watersheds, respectively, compared with 2.9% of fish released after angling and net pen recovery. Blood plasma stress indices reflected the 10-fold difference in survival, with a ∼4-fold higher plasma cortisol, a ∼2-fold higher plasma glucose and significantly depressed plasma ions and osmolality relative to fish sampled upon capture. Plasma lactate did not differ among groups. Collectively, these results suggest that a 24 h recovery in net pen following angling failed to promote post-release survival experienced with immediate release after angling or beach seining.
By settling the land claim of the aboriginal Nisga'a people of north western British Columbi... more By settling the land claim of the aboriginal Nisga'a people of north western British Columbia, Canada, governments have an opportunity to put in place an institution that will promote sustainable fisheries manage ment of River Nass fish stocks. We describe five features of the recent Agreement-in-Principle between the Nisga'a, the Canadian federal govern ment and the British Columbia provincial government that are intended to address common problems encountered in fisheries management. While the Nisga' a Fisheries Agreement takes advantage of unique features of the Nass River area, some elements of the Agreement would be applicable to other areas. By studying fisheries management under the land claim set tlement with the Nisga'a, fisheries managers may gain insight into the common fisheries management issues of community-based management, property-rights-based fisheries on highly mobile fish stocks, and mechan isms for sustainable funding of research and management.
By settling the land claim of the aboriginal Nisga'a people of north western British Columbi... more By settling the land claim of the aboriginal Nisga'a people of north western British Columbia, Canada, governments have an opportunity to put in place an institution that will promote sustainable fisheries management of River Nass fish stocks. The chapter describes five features ...
Canada’s Policy for Conservation of Wild Pacific Salmon has been heralded as a transformative app... more Canada’s Policy for Conservation of Wild Pacific Salmon has been heralded as a transformative approach to the management of wild salmon whereby conservation is the highest priority. Given that changes to the Policy are under consideration, it is timely that we understand whether our state of knowledge and the status of wild salmon in Canada have indeed improved after its adoption in 2005. To answer these questions, we used two indices of improvement: (i) monitoring effort and (ii) abundance of spawning adults. Our results, based on data for all species from British Columbia’s north and central coasts, show that monitoring effort has continued to erode, abundance of spawning adults has significantly declined for several species, the status of many salmon Conservation Units are in zones of concern, and 42% of the Conservation Units that we assessed as Red (threatened) would have improved in status had the Canadian fishery been reduced. We conclude with recommendations to help improve ...
Canadian Journal of Fisheries and Aquatic Sciences, 2013
We evaluate the utility of an inexpensive, portable recovery bag designed to facilitate recovery ... more We evaluate the utility of an inexpensive, portable recovery bag designed to facilitate recovery of fish from capture stress by combining physiological assays, biotelemetry, and social science surveys. Adult migrating Pacific salmon (Oncorhynchus spp.) were used as a model, since some of their populations are threatened. While catch-and-release is common, there is a need to ensure that it is sustainable. A social science survey revealed that anglers generally have positive attitudes towards recovery bag use, particularly if research identifies that such techniques could be effective. Physiological assays on pink salmon (Oncorhynchus gorbuscha) revealed benefits of both high- and low-velocity recovery, but high velocity was most effective with reduced plasma cortisol concentrations and similar plasma sodium and chloride concentrations as those found in controls at all recovery durations. A biotelemetry study on sockeye salmon (Oncorhynchus nerka) captured by anglers and stressed by a...
Little is known about the seasonal movements of fish that inhabit large rivers in South America, ... more Little is known about the seasonal movements of fish that inhabit large rivers in South America, which makes it difficult to identify potential threats to fish populations associated with the proliferation of hydropower developments. Dorados Salminus brasiliensis (Characiformes) are large riverine piscivores that are targeted by recreational and commercial fishers and are considered regionally 'vulnerable' in Brazil due to overfishing, pollution, and habitat fragmentation. Here, we used radio telemetry to study the seasonal movements of dorados in the upper Uruguay River, Brazil, to provide the first information on large-scale migratory biology and to inform management and conservation actions. From November 2001 to July 2003, 73 dorados were radio-tracked using aerial surveys and 7 fixed radio telemetry stations installed in a section of the upper Uruguay River covering ~400 km. Despite use of an extensive radio telemetry array and aerial tracking, nearly 40% of fish tagged at the downstream site were never detected, suggesting unreported harvest, post-release mortality, or migration to tributaries or downstream reaches that extended beyond the tracking area, emphasizing the challenges of working in such a large study system in jurisdictions where research capacity and funding are limited. Nonetheless, this study yielded the first data on the migratory biology of dorados and revealed that a segment of the population is quite mobile and thus could be negatively impacted by river fragmentation, suggesting the need for management strategies that maintain connectivity (e.g. fish passage facilities).
The American Fisheries Society (AFS), founded in 1870, is the oldest and largest professional soc... more The American Fisheries Society (AFS), founded in 1870, is the oldest and largest professional society representing fisheries scientists. The AFS promotes scientific research and enlightened management of aquatic resources for optimum use and enjoyment by the public. It also encourages comprehensive education of fisheries scientists and continuing on-the-job training.
In presenting this thesis in partial fulfilment of the requirements for an advanced degree at the... more In presenting this thesis in partial fulfilment of the requirements for an advanced degree at the University of British Columbia, I agree that the Library shall make it freely available for reference and study. I further agree that permission for extensive copying of this thesis for scholarly purposes may be granted by the head of my department or by his or her representatives. It is understood that copying or publication of this thesis for financial gain shall not be allowed without my written permission.
Commercial salmon harvests have declined dramatically for all Pacific salmon species in British C... more Commercial salmon harvests have declined dramatically for all Pacific salmon species in British Columbia, mainly over the period 1995-2000. Much of this decline is attributable to declining abundance, but some of it has been due to deliberate reduction in allowable exploitation rates. Various reasons have been given for this reduction, but the main rationale appears to have been concern about declines in a few relatively small and unproductive stocks that are intercepted in mixed-stock fisheries. Reductions in exploitation rate have generally not been followed by the increases in stock size that would be expected if overfishing had been the main cause of the declines. Current procedures for setting exploitation rate goals do not appear to involve explicit analysis of the risk-reward trade off relationship between mixed stock exploitation rates and yields.
Transactions of The American Fisheries Society, Apr 27, 2017
Details of the spatial ecology of White Sturgeon Acipenser transmontanus in the lower Fraser Rive... more Details of the spatial ecology of White Sturgeon Acipenser transmontanus in the lower Fraser River, British Columbia, are needed for habitat conservation, assessments of impacts from spatially delimited threats, and refinement of abundance estimation methods. The abundance of threatened lower Fraser River White Sturgeon is assessed annually using a Bayesian, closed-population, mark-recapture model. If individuals make prolonged departures from the lower Fraser River, either into marine waters or a tributary, the validity of the model's assumed closed population is questionable. There is also concern that fish might move far enough to be exposed to harvest in Puget Sound, Washington. From 2008 to 2012, White Sturgeon of various sizes were acoustically tagged in the Pitt River (n = 58) and in the lower reaches of the Fraser River (near Douglas Island, n = 52) to determine the timing, rate, and spatial extent of movements. Movements were monitored using acoustic receivers at 17 locations in the lowermost 92 km of the main-stem Fraser River, three in the first 21 km of the Pitt River (a tributary to the lower Fraser River), and nine in the coastal waters of British Columbia and Washington State. Travel speeds showed a strong skew toward slower movements (74% were <1 km/h) and did not differ significantly between upstream and downstream directions. On average, 33.2% of the sample was mobile (displacing~13.4 km/month) and 66.8% was sedentary (displacing~1.87 km/month). In general, White Sturgeon were significantly more sedentary during winter months and more mobile during spring and fall. Annual or seasonal migratory movements and patterns were observed for 73% of fish tracked. Repeated use of specific locations within the lower Pitt River during midwinter suggested White Sturgeon have a high fidelity for specific overwintering sites. Several of the tagged fish showed annual movements to the lowest reaches of the Fraser River for 1-3 months between May and September, although there was no direct evidence that they left the Fraser River and entered the Strait of Georgia. By contrast, there was strong evidence for extended and repeated movement into the lower Pitt River. Given that the lower Pitt River is outside the mark-recapture assessment area, our results suggest either that the area's boundaries need expansion, or alternative models should be considered for abundance estimations of lower Fraser River White Sturgeon. White Sturgeon Acipenser transmontanus are endemic to the west coast of North America, and known spawning locations occur in the Sacramento, Columbia, and Fraser rivers (McPhail 2007). Some White Sturgeon populations are anadromous (Schaffter 1997), and others live primarily in freshwater but with known marine tolerance (Veinott et al. 1999; Welch et al. 2006). In Canada, White Sturgeon are of cultural and economic importance. The species has been important to aboriginals for generations (Nelson et al. 2013b), actively targeted by anglers (Inglis and Rosenau 1994), and at one time was commercially exploited (Semakula and Larkin 1968), although overfishing caused the fishery to collapse at the turn of the last century (Echols and FRAP 1995; Ptolemy and Vennesland 2003). White Sturgeon are long-lived, latematuring fish (Semakula and Larkin 1968); thus it is not surprising that populations have been slow to recover from
There is extensive evidence that fishing is often selective for specific phenotypic characteristi... more There is extensive evidence that fishing is often selective for specific phenotypic characteristics, and that selective harvest can thus result in genotypic change. To date, however, there are no studies that evaluate whether fishing is selective for certain physiological or energetic characteristics that may influence fish behaviour and thus vulnerability to capture. Here, adult sockeye salmon (Oncorhynchus nerka) were used as a model to test the null hypothesis that fishing is not selective for specific physiological or energetic traits. Fish were intercepted during their spawning migrations, implanted with a gastric radio transmitter, and biopsied (i.e., non-lethally sampled for blood, gill tissue and quantification of energetic status). In both 2003 and 2006, we tagged and biopsied 301 and 770 sockeye salmon, respectively, in the marine environment en route to their natal river system to spawn. In 2006 an additional 378 individuals were tagged and biopsied in freshwater. We found that 23 (7.6%) of the marine fish tagged in 2003, 78 (10.1%) of the marine fish tagged in 2006 and 57 (15.1%) of the freshwater fish tagged in 2006 were harvested by one of three fisheries sectors that operate in the coastal marine environment and the Fraser River (i.e. commercial, recreational or First Nations fisheries between the site of release and Hell's Gate in the Fraser River, approximately 250 km upriver and 465 km from the ocean tagging site). However, fisheries were not open continually or consistently in different locations and for different fisheries sectors necessitating a paired analytical approach. As such, for statistical analyses we paired individual fish that were harvested with another fish of the same genetic stock that was released on the same date and exhibited similar migration behaviour, except that they successfully evaded capture and reached natal spawning grounds. Using two-tailed Wilcoxon matched pairs signed-rank tests, we revealed that the physiological and energetic characteristics of harvested fish did not differ from those of the successful migrants despite evaluating a number of biochemical (e.g. plasma metabolites, cortisol, plasma ions, gill Na + /K +-ATPase) and energetic (e.g. gross somatic energy density) variables (P's all >0.10). However, for some analyses we suffered low statistical power and the study design had several shortcomings that could have made detection of differences difficult. We suggest that additional research explore the concept of fishing-induced selection for physiological characteristics Evolutionary Applications
Canadian Journal of Fisheries and Aquatic Sciences, Mar 1, 1983
Juvenile chinook salmon, Oncorhynchus tshawytscha, were raised in 90-m3 mesh enclosures in Saanic... more Juvenile chinook salmon, Oncorhynchus tshawytscha, were raised in 90-m3 mesh enclosures in Saanich Inlet, B.C. The enclosures permitted ample water and zooplankton circulation while retaining 5–6 g juvenile salmon. Mean growth rate was 1.8% wet body weight/d over 6 wk. Weekly growth rates ranged from 3.9%/d while food was abundant, to −0.5%/d when food was scarce. Zooplankton concentration inside and outside enclosures without fish were not significantly different. Organisms associated with the sides of the enclosures (non-pelagic) were not a major contributor to the growth of the juvenile chinook. There was a strong relationship between the fish growth rates and the abundance of 1.4- to 4.5-mm zooplankton. Rates of successful search varied directly with the size and inherent contrast of a prey item. The minimum rate of successful search was 2.3 m3/h for salmon feeding on 1.4- to 4.5-mm zooplankton. This rate of successful search, while far greater than previously suspected, is still within the visual capabilities of the juvenile salmon. The enclosed salmon grew rapidly on zooplankton concentrations that were 1/1000 of those required to sustain similar growth rates in tank experiments.Key words: predator–prey relationship, planktivorous salmonid, marine, &amp;amp;amp;amp;amp;amp;quot;in situ&amp;amp;amp;amp;amp;amp;quot; enclosures, search efficiency
Canadian Journal of Fisheries and Aquatic Sciences, Jul 1, 2006
Beginning in 1995, segments of the late-run sockeye salmon (Oncorhynchus nerka) stocks from the F... more Beginning in 1995, segments of the late-run sockeye salmon (Oncorhynchus nerka) stocks from the Fraser River, British Columbia, have initiated upriver spawning migration up to 6 weeks earlier than historical records; and those fish have experienced high rates of en route mortality. We examined the correlations between physiological and energetic status prior to river entry with subsequent migratory performance of individual salmon using telemetry and noninvasive biopsies for Adams-Thompson-Shuswap (Adams) and Weaver-Harrison (W-H) stocks. Salmon that failed to reach the river were characterized by a tendency to have elevated levels of chronic and acute stress indicators. For one stock of fish (i.e., Adams) that entered the river, those that died before reaching spawning grounds were individuals with low gross somatic energy. Furthermore, females tended to have elevated plasma estradiol levels. When contrasting fish with different behaviours and fates, fish that did not hold in the estuary and subsequently died tended to have less energy than fish that held and reached spawning areas. Females from the former group also had higher 11ketotestosterone and estradiol levels relative to those from the later group. These data suggest that differences in physiological and energetic status may be associated with high en route mortality in late-run sockeye salmon. Résumé : Depuis 1995, des portions des stocks à migration tardive de saumons rouges (Oncorhynchus nerka) du Fraser, Colombie-Britannique, commencent leur migration de reproduction vers l'amont jusqu'à six semaines avant la période normale du passé et elles subissent de forts taux de mortalité durant le trajet. Nous examinons les corrélations entre les statuts physiologique et énergétique avant l'entrée en rivière et la performance subséquente de la migration chez des saumons individuels des stocks Adams-Thompson-Shuswap (Adams) et Weaver-Harrison (W-H) à l'aide de la télémétrie et de biopsies non invasives. Les saumons qui n'atteignent pas la rivière ont tendance à avoir des niveaux élevés d'indicateurs de stress chronique et aigu. Chez l'un des stocks (c.-à-d., Adams) qui a pénétré dans la rivière, les poissons qui sont morts avant d'atteindre les sites de fraye étaient des individus possédant une faible énergie somatique brute. De plus, les femelles avaient tendance à avoir des concentrations plasmatiques élevées d'oestradiol. En comparant des poissons ayant des comportements et des sorts différents, nous trouvons que les poissons qui ne se sont pas maintenus dans l'estuaire et qui sont morts subséquemment avaient tendance à avoir moins d'énergie que les poissons qui se sont maintenus et qui ont atteint les sites de fraye; les femelles du premier groupe avaient aussi des concentrations plus élevées de 11-céto-testostérone et d'oestradiol que celles du second groupe. Ces données indiquent que les statuts physiologique et énergétique peuvent être associés à une forte mortalité durant le trajet chez le saumon rouge. [Traduit par la Rédaction] Cooke et al. 1480
Few studies have examined the effects of fisheries capture on wild fish, particularly in the cont... more Few studies have examined the effects of fisheries capture on wild fish, particularly in the context of evaluating the sustainability of capture and release methods for Pacific salmon (Oncorhynchus spp.) during upriver migration. This study examined the physiological condition, post-release behaviour and survival of adult migrating sockeye salmon (O. nerka) in the Fraser River, British Columbia, Canada. Fish were captured by either beach seine or angling and released immediately, or were captured by angling and released following a 24-h recovery period in a net pen. Before release, all salmon were biopsied or tagged with radio telemetry transmitters. Capture by either angling or beach seine with immediate release resulted in >95% survival 24 h after release, whereas net pen recovery after angling resulted in ∼80% survival. This differential in survival was similarly expressed in the percentage of released fish reaching natal sub-watersheds, with 52.2% and 36.3% of fish immediately released by beach seine and angling reaching natal sub-watersheds, respectively, compared with 2.9% of fish released after angling and net pen recovery. Blood plasma stress indices reflected the 10-fold difference in survival, with a ∼4-fold higher plasma cortisol, a ∼2-fold higher plasma glucose and significantly depressed plasma ions and osmolality relative to fish sampled upon capture. Plasma lactate did not differ among groups. Collectively, these results suggest that a 24 h recovery in net pen following angling failed to promote post-release survival experienced with immediate release after angling or beach seining.
By settling the land claim of the aboriginal Nisga'a people of north western British Columbi... more By settling the land claim of the aboriginal Nisga'a people of north western British Columbia, Canada, governments have an opportunity to put in place an institution that will promote sustainable fisheries manage ment of River Nass fish stocks. We describe five features of the recent Agreement-in-Principle between the Nisga'a, the Canadian federal govern ment and the British Columbia provincial government that are intended to address common problems encountered in fisheries management. While the Nisga' a Fisheries Agreement takes advantage of unique features of the Nass River area, some elements of the Agreement would be applicable to other areas. By studying fisheries management under the land claim set tlement with the Nisga'a, fisheries managers may gain insight into the common fisheries management issues of community-based management, property-rights-based fisheries on highly mobile fish stocks, and mechan isms for sustainable funding of research and management.
By settling the land claim of the aboriginal Nisga'a people of north western British Columbi... more By settling the land claim of the aboriginal Nisga'a people of north western British Columbia, Canada, governments have an opportunity to put in place an institution that will promote sustainable fisheries management of River Nass fish stocks. The chapter describes five features ...
Canada’s Policy for Conservation of Wild Pacific Salmon has been heralded as a transformative app... more Canada’s Policy for Conservation of Wild Pacific Salmon has been heralded as a transformative approach to the management of wild salmon whereby conservation is the highest priority. Given that changes to the Policy are under consideration, it is timely that we understand whether our state of knowledge and the status of wild salmon in Canada have indeed improved after its adoption in 2005. To answer these questions, we used two indices of improvement: (i) monitoring effort and (ii) abundance of spawning adults. Our results, based on data for all species from British Columbia’s north and central coasts, show that monitoring effort has continued to erode, abundance of spawning adults has significantly declined for several species, the status of many salmon Conservation Units are in zones of concern, and 42% of the Conservation Units that we assessed as Red (threatened) would have improved in status had the Canadian fishery been reduced. We conclude with recommendations to help improve ...
Canadian Journal of Fisheries and Aquatic Sciences, 2013
We evaluate the utility of an inexpensive, portable recovery bag designed to facilitate recovery ... more We evaluate the utility of an inexpensive, portable recovery bag designed to facilitate recovery of fish from capture stress by combining physiological assays, biotelemetry, and social science surveys. Adult migrating Pacific salmon (Oncorhynchus spp.) were used as a model, since some of their populations are threatened. While catch-and-release is common, there is a need to ensure that it is sustainable. A social science survey revealed that anglers generally have positive attitudes towards recovery bag use, particularly if research identifies that such techniques could be effective. Physiological assays on pink salmon (Oncorhynchus gorbuscha) revealed benefits of both high- and low-velocity recovery, but high velocity was most effective with reduced plasma cortisol concentrations and similar plasma sodium and chloride concentrations as those found in controls at all recovery durations. A biotelemetry study on sockeye salmon (Oncorhynchus nerka) captured by anglers and stressed by a...
Little is known about the seasonal movements of fish that inhabit large rivers in South America, ... more Little is known about the seasonal movements of fish that inhabit large rivers in South America, which makes it difficult to identify potential threats to fish populations associated with the proliferation of hydropower developments. Dorados Salminus brasiliensis (Characiformes) are large riverine piscivores that are targeted by recreational and commercial fishers and are considered regionally 'vulnerable' in Brazil due to overfishing, pollution, and habitat fragmentation. Here, we used radio telemetry to study the seasonal movements of dorados in the upper Uruguay River, Brazil, to provide the first information on large-scale migratory biology and to inform management and conservation actions. From November 2001 to July 2003, 73 dorados were radio-tracked using aerial surveys and 7 fixed radio telemetry stations installed in a section of the upper Uruguay River covering ~400 km. Despite use of an extensive radio telemetry array and aerial tracking, nearly 40% of fish tagged at the downstream site were never detected, suggesting unreported harvest, post-release mortality, or migration to tributaries or downstream reaches that extended beyond the tracking area, emphasizing the challenges of working in such a large study system in jurisdictions where research capacity and funding are limited. Nonetheless, this study yielded the first data on the migratory biology of dorados and revealed that a segment of the population is quite mobile and thus could be negatively impacted by river fragmentation, suggesting the need for management strategies that maintain connectivity (e.g. fish passage facilities).
The American Fisheries Society (AFS), founded in 1870, is the oldest and largest professional soc... more The American Fisheries Society (AFS), founded in 1870, is the oldest and largest professional society representing fisheries scientists. The AFS promotes scientific research and enlightened management of aquatic resources for optimum use and enjoyment by the public. It also encourages comprehensive education of fisheries scientists and continuing on-the-job training.
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Papers by Karl English