Fisheries and Oceans Canada (DFO; French: Pêches et Océans Canada, MPO), is a department of the Government of Canada that is responsible for developing and implementing policies and programs in support of Canada's economic, ecological and scientific interests in oceans and inland waters. Its mandate includes responsibility for the conservation and sustainable use of Canada's fisheries resources while continuing to provide safe, effective and environmentally sound marine services that are responsive to the needs of Canadians in a global economy.The federal government is constitutionally mandated for conservation and protection of fisheries resources in all Canadian fisheries waters. However, the department is largely focused on the conservation and allotment of harvests of salt water fisheries on the Atlantic, Pacific and Arctic coasts of Canada. The department works toward conservation and protection of inland freshwater fisheries, such as on the Great Lakes and Lake Winnipeg through cooperative agreements with various provinces. Provincial governments have enacted provincial fisheries legislation, for the licensing of their fisheries. With the exception of Saskatchewan, conservation rules for freshwater fisheries are enacted under the Fisheries Act; six provinces administer these regulations in their own fisheries.To address the need for conservation, the department has an extensive science branch, with research institutes across the country. Typically the science branch provides evidence for the need of conservation of various species, which are then regulated by the department. DFO also maintains a large enforcement branch with peace officers (known as fishery officers) used to combat poaching and foreign overfishing within Canada's Exclusive Economic Zone.DFO is responsible for several organizations, including the Canadian Coast Guard, the Freshwater Fish Marketing Corporation and the Canadian Hydrographic Service..
Ecological science, effective fisheries management, and conservation all benefit from an understanding of how larval dispersal links geographically distinct regions. An important but understudied aspect of such connectivity is how it can vary on different time scales. Using a high-resolution biophysical model, this study examines the temporal variability of larval connectivity of the Atlantic sea scallop (Placopecten magellanicus) due to spawning across interannual, seasonal, intra-month, and tidal scales in the Gulf of Maine and Scotian Shelf. The results reveal substantial interannual variability, with an average coefficient of variation (CV) of 44% for the major connectivity pathways, and suggest that the large-scale oceanographic changes strongly influence interannual variations of larval transport. Seasonal variations are also significant: larvae spawned in spring experience longer pelagic larval durations (PLDs) due to cooler temperatures, while fall-spawned larvae grow faster, resulting in shorter PLDs. On the intra-month time scale, the average CV is 26% for the major connectivity pathways, with the connectivity variability at this scale exceeding interannual variability in certain regions. Additionally, this study shows that tidal processes play a key role in changing larval transport pathways in regions with strong tidal currents, such as Georges Bank and the Bay of Fundy. These high-frequency connectivity fluctuations are introduced by the timing of larval spawning relative to tidal phases, which, in turn, are driven by the periodic spatial shifts of the Lagrangian coherent structures in ocean flows. The findings underscore the need to take into account multi-scale temporal variability into larval dispersal models in order to capture those fluctuations to accurately represent connectivity patterns and inform management strategies.
ABSTRACT Goldfish (Carassius auratus) is a globally invasive species commonly found in urban environments due to releases associated with the aquarium trade. Environmental DNA (eDNA) represents a novel, cost‐efficient, and sensitive technique to indirectly detect aquatic organisms by analyzing residual genetic material in environmental samples. We utilized eDNA to monitor invasive goldfish in 29 urban ponds near Hamilton, Ontario, evaluating both detection sensitivity of eDNA in comparison to conventional fisheries survey methods (electrofishing and seining) and the quantitative relationship between eDNA concentration and population abundance and biomass, determined from population censuses obtained following complete draining of eight ponds. Water samples from each pond were collected to detect and estimate the concentration of goldfish eDNA using a targeted qPCR assay. Samples from a subset of ponds were also collected and processed independently by two different working groups to evaluate the replicability of findings. Estimated pond eDNA concentrations were highly replicable across working groups; individual samples collected from the same sampling station and mean pond concentration estimates exhibited extremely strong correlations (R2 = 0.95 and R2 = 0.99, respectively). Detection limits using eDNA, in comparison to conventional surveys, were low; a single water sample from a pond, for example, would be needed to detect goldfish at a density corresponding to approximately a single fish per 10 min of electrofishing. A single sample was sufficient for detection in all but one (inhabited by a single goldfish) of the nine drained ponds. eDNA concentration in drained ponds was also positively correlated with allometrically scaled mass (mean R2 = 0.72) and abundance (mean R2 = 0.71), but not with total biomass (mean R2 = 0.28). Collectively, we demonstrate that eDNA is a replicable and effective technique to detect and monitor aquatic invasive species in urban ponds and may prove suitable for inclusion in management programs.
Trophic connections between the food web base and zooplankton affect the structure of marine food webs and fluxes to higher predators. The food that zooplankton consume shifts in response to prey resources, but specific zooplankton trophic sources remain unresolved over the dynamic seasonal cycle for many species. We investigated the food web pathways from basal production to 10 meso- and macrozooplankton species at six times over an annual cycle at a temperate coastal site, using fatty acid and stable isotope trophic markers. In addition, we concurrently characterized the zooplankton prey field through three size fractions of particulate organic matter (POM) to relate zooplankton trophic sources to specific components of primary production. Distinct stable isotope and fatty acid signatures of POM size classes enabled the identification of different pathways that support zooplankton. Overall, we found strong ties to pico-POM based production, challenging the expectation that productive coastal regions are sustained by micro-phytoplankton like diatoms. Zooplankton displayed widespread trophic flexibility and large seasonal differences in trophic markers, including varying by up to > 1 trophic position within species, with several taxa exhibiting seasonally shifting trophic associations. Despite this, inter-specific differences were the greatest source of variability for zooplankton stable isotopes and fatty acids, which generally corresponded to established trophic roles and feeding types. Defining the seasonal trophic sources to zooplankton is the first step to mechanistically link the food web base to higher trophic levels and to understand how shifts in phytoplankton size structure under climate change will influence higher trophic levels.
Objective Catch and release is a common conservation and management tactic that is used in marine Coho Salmon Oncorhynchus kisutch fisheries in British Columbia, Canada. Recent studies have found higher levels of release mortality when Coho Salmon are injured, but the role of specific gears or practices in causing injuries has not been explored for Coho Salmon that are released at sea.Methods We compared fishing injuries for Coho Salmon (n = 226) that were captured by two hook sizes (3/0 or 5/0) and three landing methods (knotless rubber-coated net, knotted polyethylene net, or no net). The captured adult Coho Salmon were then tagged and released with acoustic transmitters and tracked along their return migrations through the Salish Sea using an acoustic receiver network.Results Hook size had no effect on frequency of any hooking injuries (eye injuries and bleeding). The fish that were landed with knotless nets exhibited less scale loss than those that were landed with knotted nets but had a greater number of fins damaged. The fish that were landed without a net had the least scale loss and fin damage but were smaller overall than those that were landed with a net, so size differences may have influenced injury outcomes to some extent. Coho Salmon with less scale loss and larger body size had higher survival to a line of acoustic receivers that were located 50 km away in the Salish Sea. When considering multiple injuries, survival was compromised in fish that were in poor condition relative to those that were in good condition (37.2 vs. 21.4% release mortality, respectively; odds ratio = 2.04, P = 0.044).Conclusions These results indicate that reducing handling and netting (i.e., releasing fish at the waterline) will minimize injuries and improve release survival. We use our results to recommend best practices for capture and release of Coho Salmon at sea. Catch and release helps conserve Coho Salmon in British Columbia, but some die after release. In 226 tagged Coho Salmon, hook size did not affect injury. Fish released without nets had the fewest injuries. Larger fish and those with less scale loss had higher survival.
Dispersal is an important mechanism linked with population viability. Increases in species-specific dispersal allow for improved connectivity between habitat patches and populations. Here, we seek to understand the role of both biotic and abiotic factors, and their interactions, in influencing the movement of the recently identified and federally threatened Rocky Mountain sculpin (Cottus sp.). We conducted a mark-recapture study in a 400 m reach of Lee Creek in Alberta, Canada, using passive integrated transponder and visible implant elastomer tags across approximately 4 months. Boosted regression tree models were used to assess the movement of (1) all recaptured individuals (global model) and (2) only mobile individuals (movement only model) in response to abiotic and biotic factors. Biotic factors, such as congeners at the destination (8.7
