IFR News

The roles of extrinsic and intrinsic factors in the freshwater life-history dynamics of a migratory salmonid

July 11, 2018.

Key life-cycle transitions, such as metamorphosis or migration, can be altered by a variety of external factors, such as climate variation, strong species interactions, and management intervention, or modulated by density dependence. Given that these life-history transitions can influence population dynamics, understanding the simultaneous effects of intrinsic and extrinsic controls on life-history expression is particularly relevant for species of management or conservation importance. Here, we examined how life histories of steelhead (Oncorhynchus mykiss) are affected by weather, pink salmon abundance (Oncorhynchus gorbuscha), experimental nutrient addition, and density-dependent processes. We tested for impacts on the size of steelhead smolts (juveniles migrating to the sea), as well as their age and abundance across four decades in the Keogh River, British Columbia, Canada. Larger steelhead smolts were associated with warmer years and artificial nutrient addition. In addition, higher pink salmon abundance and artificial nutrient addition correlated with juvenile steelhead migrating at younger ages. While density dependence appeared to be the primary factor regulating the abundance of steelhead smolts, nutrient addition and temperature were positively and negatively associated with smolt production, respectively, prior to 1991, and pink salmon spawning abundance was positively associated with smolt production after 1990. Thus, this study provides evidence that the temporal dynamics of one species of salmon is linked to the juvenile life history of co-occurring steelhead. A complex interplay of species interactions, nutrient subsidies, density dependence, and climatic variation can control the life-history expression of species with complex life cycles. Read more.

Bailey, C. J., D. C. Braun, D. McCubbing, J. D. Reynolds, B. Ward, T. D. Davies, and J. W. Moore. 2018. The roles of extrinsic and intrinsic factors in the freshwater life-history dynamics of a migratory salmonid. Ecosphere 9(9): e02397. 10.1002/ecs2.2397

Evidence for Freshwater Residualism in Coho Salmon, Oncorhynchus kisutch, From a Watershed on the North Coast of British Columbia

October 14, 2016

Key life-cycle transitions, such as metamorphosis or migration, can be altered by a variety of external factors, such as climate variation, strong species interactions, and management intervention, or modulated by density dependence. Given that these life-history transitions can influence population dynamics, understanding the simultaneous effects of intrinsic and extrinsic controls on life-history expression is particularly relevant for species of management or conservation importance. Here, we examined how life histories of steelhead (Oncorhynchus mykiss) are affected by weather, pink salmon abundance (Oncorhynchus gorbuscha), experimental nutrient addition, and density-dependent processes. We tested for impacts on the size of steelhead smolts (juveniles migrating to the sea), as well as their age and abundance across four decades in the Keogh River, British Columbia, Canada. Larger steelhead smolts were associated with warmer years and artificial nutrient addition. In addition, higher pink salmon abundance and artificial nutrient addition correlated with juvenile steelhead migrating at younger ages. While density dependence appeared to be the primary factor regulating the abundance of steelhead smolts, nutrient addition and temperature were positively and negatively associated with smolt production, respectively, prior to 1991, and pink salmon spawning abundance was positively associated with smolt production after 1990. Thus, this study provides evidence that the temporal dynamics of one species of salmon is linked to the juvenile life history of co-occurring steelhead. A complex interplay of species interactions, nutrient subsidies, density dependence, and climatic variation can control the life-history expression of species with complex life cycles. Read more.

Parkinson, Eric A.,Chris J. Perrin, Daniel Ramos-Espinoza, and Eric B. Taylor. 2016. Evidence for fresh water residualism in Coho Salmon, Oncorhynchuskisutch, from a watershed on the north coast of British Columbia. Canadian Field-Naturalist 130(4): 336–343.


IFR deploy first Vaki Riverwatcher counter in western Canada

November 17, 2016

IFR is collaborating with Vaki, Fisheries and Oceans Canada and Metro Vancouver to test a Riverwatcher optical beam counter at the Cariboo Dam in Burnaby, BC. IFR will be counting chum and coho salmon, and steelhead trout from November 2016 to March 2017.

cariboo_vaki

The Riverwatcher is triggered when a beam of light is broken by a fish passing through the unit, creating a silhouette image of each fish. Once the counter registers an up or down count, the passage event is recorded by an underwater camera unit. IFR will be examining whether silhouette images and video footage can be used to determine species and hatchery origin (adipose fin present or absent).

silhouettes

(Left) 79 cm wild (adipose fin present) chum salmon. (Right) 69 cm hatchery (adipose fin absent) coho salmon.

The Riverwatcher counter is directly linked to a website, Riverwatcher Daily, that provides daily summaries of up and down counts past the counter. More detailed summaries (size distribution and migration timing) are provided here.


No respect for the spineless

July 26, 2016

Taxonomic bias and international biodiversity conservation research
Michael R. Donaldson, Nicholas J. BurnettDouglas C. Braun, Cory D. Suski, Scott G. Hinch, Steven J. Cooke, Jeremy T. Kerr

While greater research on threatened species alone cannot ensure their protection, understanding taxonomic bias may be helpful to address knowledge gaps in order to identify research directions and inform policy. Using data for over 10 000 animal species listed on the International Union for Conservation of Nature Red List, we investigated taxonomic and geographic biodiversity conservation research trends worldwide. We found extreme bias in conservation research effort on threatened vertebrates compared with lesser-studied invertebrates in both terrestrial and aquatic habitats at a global scale. Based on an analysis of common threats affecting vertebrates and invertebrates, we suggest a path forward for narrowing the research gap between threatened vertebrates and invertebrates.


Mitigating carryover effects of dam passage

July 12, 2016

Reducing carryover effects on the migration and spawning success of sockeye salmon through a management experiment of dam flows
Nicholas J. Burnett, Scott G. Hinch, Nolan N. Bett, Douglas C. Braun, Matthew T. Casselman, Steven J. Cooke, Ahmed Gelchu, Stephanie Lingard, Collin T. Middleton, Vanessa Minke‐Martin, Carson F.H. White

Effective dam management requires an understanding of the ecological impact of a facility and its operations on individual fish and fish populations. Traversing high flows downstream of dams is an energetically challenging activity that could influence survival and spawning success following passage. Carryover effects, however, are an underappreciated consequence of dam passage that have been overlooked by researchers and natural resource managers. We conducted a large-scale management experiment to determine if the operation of dam attraction flows could be changed to reduce high sockeye salmon Oncorhynchus nerka mortality following passage and increase spawning success. We tested two flow conditions: (i) a baseline condition—currently used by managers—that released high attraction flows directly adjacent to the entrance to a vertical-slot fishway and (ii) an alternative condition that released attraction flows 10 m away from the fishway entrance to reduce the flows fish swim through while approaching the passage structure. We tagged 637 sockeye salmon with telemetry tags to monitor dam passage, post-passage survival to spawning grounds and spawning success under the two flow conditions. Validated fish counters at the exit of the fishway and on spawning grounds were used to generate population level estimates of survival to spawning grounds. Individuals exposed to baseline flow conditions spent two times longer recovering from dam passage and exhibited 10% higher mortality following passage than those exposed to alternative flows. Release of alternative flows for 10 days assisted approximately 550 fish (or 3% of total spawners) in reaching spawning grounds. Once on spawning grounds, female spawning success was strongly influenced by individual spawning characteristics (longevity and date of arrival on spawning grounds) and not dam flow condition. Our findings highlight a cost-effective solution that decreases mortality following passage simply by altering the location of dam flow releases and not reductions in discharge.


Egg size and parity in salmon

June 1, 2016

Costs of reproduction can explain the correlated evolution of semelparity and egg size: theory and a test with salmon
Holly K. Kindsvater, Douglas C. Braun, Sarah P. Otto, John D. Reynolds

Species’ life history traits, including maturation age, number of reproductive bouts, offspring size and number, reflect adaptations to diverse biotic and abiotic selection pressures. A striking example of divergent life histories is the evolution of either iteroparity (breeding multiple times) or semelparity (breed once and die). We analysed published data on salmonid fishes and found that semelparous species produce larger eggs, that egg size and number increase with salmonid body size among populations and species and that migratory behaviour and parity interact. We developed three hypotheses that might explain the patterns in our data and evaluated them in a stage-structured modelling framework accounting for different growth and survival scenarios. Our models predict the observation of small eggs in iteroparous species when egg size is costly to maternal survival or egg number is constrained. By exploring trait co-variation in salmonids, we generate new hypotheses for the evolution of trade-offs among life history traits.


Marine Scotland Science publishes IFR technical review of counters

March 22, 2016

IFR conducted a comprehensive technical review of electronic counter technologies for Marine Scotland Science to inform the development of a counter network for Scotland. Click here for the review.