A5031021344- Marine and fisheries research
- Fish Ecology and Management Studies
- Marine Bivalve and Aquaculture Studies
- Fish Biology and Ecology Studies
- Marine animal studies overview
- Coral and Marine Ecosystems Studies
- Genetic and phenotypic traits in livestock
- Genetic diversity and population structure
- Ichthyology and Marine Biology
- Animal Behavior and Reproduction
- Morphological variations and asymmetry
- Identification and Quantification in Food
- Avian ecology and behavior
- Wildlife Ecology and Conservation
- Fish biology, ecology, and behavior
- Aquaculture Nutrition and Growth
- Simulation Techniques and Applications
- Isotope Analysis in Ecology
- Crustacean biology and ecology
- Market Dynamics and Volatility
- Mathematical and Theoretical Epidemiology and Ecology Models
- Amphibian and Reptile Biology
- Reproductive biology and impacts on aquatic species
- Diverse Academic Research Areas
- Marine Ecology and Invasive Species
Fisheries and Oceans Canada
2012-2024
Ministry of Agriculture & Farmers Welfare
2014
University of Copenhagen
2010
Technical University of Denmark
2010
Google (United States)
2008
University of British Columbia
1992
Many collapsed fish populations have failed to recover after a decade or more with little fishing. This may reflect evolutionary change in response the highly selective mortality imposed by fisheries. Recent experimental work has demonstrated rapid genetic growth rate size-selective harvesting of laboratory populations. Here, we use 30-year time-series back-calculated lengths-at-age test for wild heavily exploited population Atlantic cod (Gadus morhua). Controlling effects density- and...
We compared agonistic behavior of newly emerged coho salmon (Oncorhynchus kisutch) between hatchery and wild populations using mirror image stimulation tests. used from two different regions Vancouver Island B.C., each matched with a population its region. In both comparisons, juveniles were more aggressive than juveniles. Rates display increased time since emergence for fish, as did the differences in types. By sixth day observation (13 d postemergence), overall effect fish type was highly...
Previous studies have demonstrated morphological differences between hatchery-reared coho salmon (Oncorhynchus kisutch) of hatchery origin and wild-reared wild origin. We tested for a genetic component to this divergence by comparing from populations both reared in the same environment an environmental hatchery- As previous studies, fish had greater head dimensions, larger median fins, deeper bodies than did populations. This difference, summarized first principal (PC1) size-adjusted data,...
Neither the scale of adaptive variation nor genetic basis for differential population responses to environment is known broadcast-spawning marine fishes. Using a common-garden experimental protocol, we document how larval growth, survival and their norms reaction differ genetically among four populations Atlantic cod ( Gadus morhua ). These traits, plastic food temperature, differed across spatial scales at which microsatellite DNA failed detect structure. Divergent indicate that warm-water...
Juvenile coho salmon (Oncorhynchus kisutch) rear both in Mesachie Lake, B.C., and its inlet stream. The duration frequency of aggressive behavior were greater among stream-rearing than lake-rearing juveniles mirror image stimulation stream tank tests agonistic behavior. Lateral displays made up a higher proportion total the fish compared with fish. Lake-type had more posteriorly placed pectoral fins, shallower bodies smaller, less brightly colored dorsal anal fins did stream-type fish, even...
Catchability to commercial fisheries has been predicted be density dependent due density-dependent variation in stock area. Previous studies have used indices of area based on thresholds absolute density. These will increase with abundance even if increases uniformly over all areas. We show that spatially uniform changes can affect catchability given certain models for the distribution fishing effort, but this effect is slight compared spatial spread fish distribution. describe an index...
Like most other stocks of Atlantic cod (Gadus morhua) in the Northwest Atlantic, southern Gulf St. Lawrence declined to low abundance early 1990s. Recovery has been slow contrast with rapid recovery from similar levels mid-1970s. This difference reflects remarkably high prerecruit survival earlier period rather than unusually poor The coincided collapse herring (Clupea harengus) and mackerel (Scomber scombrus) resulting overfishing. These pelagic fishes are potential predators or competitors...
The relative importance of size-selective mortality, density-dependent growth, and temperature on growth a commercial fish population was investigated using an integrated statistical analysis. Two indices mortality were determined otolith backcalculations. One index measured the direct effect mean increments in year increment. second cumulative potential cohort. Indices density, occupied temperature, bottom developed from annual synoptic research vessel surveys population. We simultaneously...
We tested effects of population size on the geographic distribution Atlantic cod (Gadus morhua) in southern Gulf St. Lawrence for age groups 3–8+ over period 1971–90. Distribution was density dependent all six groups. Geographic range or stock area increased with abundance each group. Variation explained 63–94% variation area. During periods low abundance, highest densities occurred western regions during these more restricted younger than older cod. Density age-3 relatively high only one...
Fisheries-induced evolution has been hypothesized to delay the recovery of collapsed fish stocks through effects on their productivity. The cod stock in southern Gulf St. Lawrence (SGSL) early 1990s and shown no since then, due mainly high natural mortality adult cod. Age size at maturation SGSL decreased sharply over time cohorts produced 1950s 1960s, likely reflecting an evolutionary response intensified fishing, have remained low despite severe reductions fishing past 15 years. A...
We describe dramatic shifts in the species composition of marine fish community southern Gulf St. Lawrence using a 35-year time series catch rates an annual bottom-trawl survey. attempt to understand causes these changes traits-based approach that relates similarity among their abundance trends similarities ecological traits. selected traits based on priori beliefs how each should reflect susceptibility different external factor potentially affecting community. found evidence for effect...
Little is known about how quickly natural populations adapt to changes in their environment and temporal spatial variation selection pressures interact shape patterns of genetic diversity. We here address these issues with a series genome scans four overfished Atlantic cod (Gadus morhua) studied over an 80-year period. Screening >1000 gene-associated single-nucleotide polymorphisms (SNPs) identified 77 loci that showed highly elevated levels differentiation, likely as effect directional...
Abstract The World Conference on Stock Assessment Methods (July 2013) included a workshop testing assessment methods through simulations. exercise was made up of two steps applied to datasets from 14 representative fish stocks around the world. Step 1 involved applying stock assessments with varying degrees effort dedicated optimizing fit. 2 subset and characteristics given model fits being used generate pseudo-data error. These were then provided modellers consistency checks within...
Most stocks of Atlantic cod (Gadus morhua) in the Northwest collapsed early 1990s, with little sign recovery since then. In southern Gulf St. Lawrence (sGSL), failed is due to severe increases natural mortality adult cod. We examined role predation by grey seals (Halichoerus grypus) this directly incorporating seal population model for via a functional response. Estimated increased sharply during collapse and has continued increase, comprising majority late 1990s. While appeared play minor...
A 28-year time series (19711998) of backcalculated length-at-age was used to investigate changes in the direction and magnitude size-selective mortality prerecruit adult Atlantic cod (Gadus morhua) southern Gulf St. Lawrence, Canada. Size selection changed from favouring fast growth 1970s slow late 1980s 1990s. There an intervening period disruptive where favoured while intermediate rates were selected against. The intensity size declined at end study following closure commercial fishery....
Previous studies have demonstrated selective predation for vertebral traits of larvae in the stickleback Gasterosteus aculeatus. I tested hypothesis that this selection results from a direct functional advantage to particular phenotypes by measurement burst swimming performance larvae. Within narrow window lengths, speed did depend on phenotype. As previous experiments, was related more directly ratio abdominal caudal vertebrae (VR) than total number (VN), and optimal VR decreased as larval...
A common-garden experiment was conducted on larvae to test for genetic differences in body shape among populations of Atlantic cod (Gadus morhua). Offspring from four north-west regions were reared hatching postmetamorphosis at two temperatures (7 ± 1 °C and 11 °C) food levels (1500 4500 prey L−1). Body differed between treatments. Population greatest south-west Scotian Shelf those further north; the former characterized by a deeper body, larger head, longer caudal peduncle than other...
Atlantic cod ( Gadus morhua ) was the dominant demersal fish and most important predator in southern Gulf of St. Lawrence ecosystem as recently 1980s. However, productivity has declined, population is no longer viable even absence fishing. We conducted projections taking into account uncertainty current abundance-at-age or variability each components (i.e., rates recruitment, individual growth, adult natural mortality). defined extirpation a spawning stock biomass less than 1000 t (<0.3%...
Diel feeding patterns of herring Clupea harengus and mackerel Scomber scombrus in the southern Gulf St Lawrence were examined based on samples obtained by midwater trawling between 19 26 June 2001. Within 3 h time periods, stomach contents tended to be more similar fish from same tow than different tows. Thus, contrast previous diet studies, which have used individual stomachs as independent observations, was experimental unit statistical analyses this study. fullness identified using...
Variation in morphological traits is generally thought to be cogradient, with environmental effects on phenotypic expression reinforcing genetic differences between populations. We compared body shape two populations of Atlantic cod ( Gadus morhua ). Striking occurred juveniles from the when reared a common laboratory environment. However, no difference wild-reared populations, suggesting that were obscured by opposing experienced wild. suggest much diversity fishes may cryptic, stabilizing...
The ideal free distribution (IFD), a hypothesis from behavioural ecology, predicts that fishery effort should map resource better than catch-per-unit-effort (CPUE) when interference competition occurs in the fishery. We tested this prediction using data and annual research survey for snow crab (Chionoecetes opilio) southern Gulf of St. Lawrence. Effort was positively correlated with local abundance crabs all years. Correlations between CPUE were also positive some years, but negative others....
More than 10 years after the collapse of Atlantic cod (Gadus morhua) fisheries in Canada, role increased seal populations decline and lack recovery stocks continues to be discussed. Using removals abundance indices from synthetic populations, we found that sequential population analysis can uncover trends natural mortality. We used this approach examine variation mortality (M) southern Gulf St. Lawrence cod. M late 1970s mid-1990s but declined slightly recently. Results were consistent with...
Worldwide, many commercial fish stocks have experienced dramatic declines due to overfishing. Such fisheries-induced population reductions could potentially erode the genetic diversity of marine populations. Based on analyses DNA extracted from archived and contemporary samples, this paper compares variability at nine microsatellite loci in a Canadian Atlantic cod ( Gadus morhua ) over 80 years, spanning before fishery intensified now when is historically low abundance. Extensively validated...