Home /Search
Search datasets
We have found 180 datasets for the keyword " rock crab". You can continue exploring the search results in the list below.
Datasets: 106,103
Contributors: 42
Results
180 Datasets, Page 1 of 18
Scientific trawl surveys of American lobster (Homarus americanus) and rock crab (Cancer irroratus) in the Magdalene Island
A research survey on American lobster (Homarus americanus) and rock crab (Cancer irroratus) has been carried out annually on the Magdalen Islands since 1995 to assess the abundance and structure of populations in this area. The survey is carried out during the first two weeks of September and covers the southern part of the Magdalen Islands, from "Baie de Plaisance" to "Grande-Entrée", extending slightly eastwards between "Havre-aux-Maisons" and "Grande-Entrée". The survey lasts 8 to 15 days, depending of the weather conditions, and covers a maximum of 48 stations. Approximately half of the stations are surveyed in duplicate (two tows per station). The tows always cover 500 meters, with a slightly variable trawl opening (as explained above), averaging around 10 meters.The gear used is a Nephrops trawl, a benthic trawl originally developed for langoustine fishing in Brittany, but slightly modified to target lobster. The trawl is deployed from the CCGS Leim and the harvested organisms are hauled aboard and sorted. Cephalothorax length, sex and shell stage are recorded for all lobsters. This is supplemented by information on reproductive conditions for certain size classes, and dissections of 25 males and 25 females per mission. Rock crabs are also included in the survey and are counted with additional measurements of shell width, sex and shell condition that are recorded on predetermined stations. For other stations individuals data are collected depending on the time available between trawl hauls.The publication contains 4 files; the "Information_stations" file which contains the data of the stations, the "Data_homard_lobster_survey" file which contains the measurements of each lobster, the "Nombre_crabe_crab_number" file which contains the count of rock crabs, the "Mesure_crabe_crab_measurement" file contains the characteristics measured for each crab. Each of the files can be linked by the "date", "st", "tr" columns. The “bat” column notes the boat code, because the gear is not deployed in the same way on each boat.*This record consist of raw data and quality has not been verifiedAssociated species are identified and semi-quantitatively counted directly on the sorting table, and the results are presented in the following publication: https://open.canada.ca/data/en/dataset/99cb7034-f3d5-4da4-a5bc-e81315cfb8eb
Likelihood of Presence of Snow Crab in Area Response Planning Pilot Areas
Likelihood of presence of Snow Crab in the Bay of Fundy and Port Hawkesbury areas. The Coastal Oceanography and Ecosystem Research section (DFO Science) reviewed science sources and local knowledge sources to estimate where Snow Crab are seasonally present and delineate these areas. As of March 2017, this dataset delineates the presence of snow crab in the Bay of Fundy and Port Hawkesbury areas of Nova Scotia designated within the Area Response Planning (ARP), identified under the World Class Tanker Safety System (WCTSS) initiative, based on the Transport Canada's Response Organizations Standards.A version of this dataset was created for the National Environmental Emergency Center (NEEC) following their data model and is available for download in the Resources section.Cite this data as: Lazin, G., Hamer, A.,Corrigan, S., Bower, B., and Harvey, C. Data of: Likelihood of presence of Snow Crab in Area Response Planning pilot areas. Published: June 2018. Coastal Ecosystems Science Division, Fisheries and Oceans Canada, St. Andrews, N.B. https://open.canada.ca/data/en/dataset/edb15c7b-d901-46b0-a460-1aca22c013ea
Coastwide distribution of Dungeness crab
This dataset contains two geotiff layers. The first layer (1) represents the coastwide distribution of Dungeness crab as predicted from a geostatistical model. The model predicts the mean coastwide probability of Dungeness crab detection using trap sampling gear. The second layer (2) represent the uncertainty in those predictions. Detailed descriptions of these data products can be found in Nephin et al. (2023) and the code used to produce them can be found at https://gitlab.com/dfo-msea/dungeness-sdm/.The objectives of this work was to model the habitat of Dungeness crab (_Metacarcinus magister_), a data-limited coastal marine species, to evaluate the efficacy of data integration when making predictions to geographic areas larger than the area covered by any one data source. In British Columbia, Dungeness crab are sampled regionally and sporadically with a variety of sampling gears and survey protocols, making them an ideal case study to investigate whether the integration of disparate surveys can improve habitat predictions. To that aim, we assemble data from dive, trawl, and baited-trap surveys to generate six candidate generalized linear mixed-effect models with spatial random fields. This dataset contains the mean (1) and difference (2) between the Survey-effect and Gear-effect model predictions.
Biodiversity of the snow crab trawl survey on the Lower North Shore of the Gulf of St. Lawrence (2018)
A research survey on snow crab (Chionoecetes opilio) was conducted from July 1 to July 17, 2018 on the Lower North Shore of the Gulf of St. Lawrence between Havre-Saint-Pierre and Blanc-Sablon. The main objective of this survey was to assess the abundance of snow crab and benthic species associated with snow crab habitat. Only data for benthic species associated with snow crab habitat are presented in this dataset.Data were collected according to a fixed station sampling design consisting of 61 stations, between 46 and 230 meters depth. Specimens were collected using a beam trawl with a total width of 2.8 meters and a total height of 0.76 meters. The codend was lined with a 16 millimeter stretched mesh net in order to harvest the small individuals. The hauls were made at a target speed of 2 knots and a target duration of 10 minutes depending on seabed conditions. Start and end positions were recorded to calculate the distance traveled on each tow using the geosphere library in R. The average tow distance was approximately 25 m. The area covered at each tow was the product of the trawl opening and the distance traveled.The two files provided (DarwinCore format) are complementary and are linked by the "eventID" key. The "Activity_Information" file includes generic activity information, including date and location. The "occurrence_taxon" file includes the taxonomy of the species observed, identified to the species or lowest possible taxonomic level. To obtain the abundance and biomass assessment, contact Cedric Juillet (cedric.juillet@dfo-mpo.gc.ca).For quality controls, all taxonomic names were checked against the World Register of Marine Species (WoRMS) to match recognized standards. The WoRMS match was placed in the "ScientificIDname" field of the occurrence file. Special cases were noted in the "commentsIdentification" field and selected specimens were confirmed with field photos. Data quality checks were performed using the R obistools and Worms libraries. All sampling locations were spatially validated.
Biodiversity of the snow crab trawl survey in Ste-Marguerite Bay, in the Gulf of St-Lawrence (2006-2009)
A research survey on snow crab (Chionoecetes opilio) was conducted from May 2006 to May 2009 in the Bay of Ste. Marguerite near Sept-Îles, Quebec. The main objective of this survey was to assess the abundance of snow crab and benthic species associated with snow crab habitat. Only data for benthic species associated with snow crab habitat are presented in this dataset.Data were collected according to a fixed station sampling design consisting of 79 stations, between 7 to 198 meters depth. Specimens were collected using a beam trawl. The codend was lined with a small stretched mesh net in order to harvest the small individuals. The hauls were made at a target duration of 15 minutes. Start and end positions were recorded to calculate the distance traveled on each tow using the geosphere library in R. The two files provided (DarwinCore format) are complementary and are linked by the "eventID" key. The "Activity_Information" file includes generic activity information, including date and location. The "occurrence_taxon" file includes the taxonomy of the species observed, identified to the species or lowest possible taxonomic level. To obtain the abundance and biomass assessment, contact Bernard Sainte-Marie (Bernard.Sainte-Marie@dfo-mpo.gc.ca).For quality controls, all taxonomic names were checked against the World Register of Marine Species (WoRMS) to match recognized standards. The WoRMS match was placed in the "ScientificnameID" field of the occurrence file. Data quality checks were performed using the R obistools and worrms libraries. All sampling locations were spatially validated.
Biodiversity of the snow crab trawl survey in the St. Lawrence Estuary (2019)
A research survey on snow crab (Chionoecetes opilio) was conducted from July 7 to July 26, 2019 in the Estuary St. Lawrence River between Forestville, Baie-Comeau and Matane. The main objective of this survey was to assess the abundance of snow crab and benthic species associated with snow crab habitat. Only data for benthic species associated with snow crab habitat are presented in this dataset.Data were collected according to a fixed station sampling design consisting of 66 stations, between 31 and 279 meters depth. Specimens were collected using a beam trawl with a total width of 2.8 meters and a total height of 0.76 meters. The codend was lined with a 16 millimeter stretched mesh net in order to harvest the small individuals. The hauls were made at a target speed of 2 knots and a target duration of 15 minutes. Start and end positions were recorded to calculate the distance traveled on each tow using the geosphere library in R. The average tow distance was approximately 25 m. The area covered at each tow was the product of the trawl opening and the distance traveled.The two files provided (DarwinCore format) are complementary and are linked by the "eventID" key. The "Activity_Information" file includes generic activity information, including date and location. The "occurrence_taxon" file includes the taxonomy of the species observed, identified to the species or lowest possible taxonomic level. To obtain the abundance and biomass assessment, contact Cedric Juillet (cedric.juillet@dfo-mpo.gc.ca).For quality controls, all taxonomic names were checked against the World Register of Marine Species (WoRMS) to match recognized standards. The WoRMS match was placed in the "ScientificnameID" field of the occurrence file. Data quality checks were performed using the R obistools and worrms libraries. All sampling locations were spatially validated.
Snow Crab Collaborative Post-season Trap Survey
This project was completed by the Shellfish Section in the Newfoundland and Labrador Science Branch of Fisheries and Oceans Canada (DFO), in collaboration with industry partners. The Coastal Environmental Baseline program supported the Placentia Bay portion of project work for an ongoing industry-DFO collaborative post-season trap survey for Snow Crab that was initiated in 2003 and has occurred each year. This survey is conducted by Snow Crab harvesters accompanied by at-sea observers and takes place in NAFO Divisions 2J3KLNOP4R. Historically the survey focused on commercial fishing grounds but began transitioning to a partly random stratified design in 2017. Since 2018, approximately 50% of survey stations are randomly allocated while 50% remain fixed. At each station, six (for inshore stations) or ten (for offshore stations) commercial traps are set in a fleet. To gather data on non-commercial sized Snow Crab, including females, many fleets also include one small-mesh trap. The coverage of small-mesh traps has been expanding in recent years with the aim of one small-mesh trap for every station in the coming years. Biological sampling is undertaken on at least one commercial trap and the small-mesh trap at each station. The data from this survey is incorporated into the annual stock assessment for Snow Crab in the Newfoundland and Labrador region. This record contains trap locations for Placentia Bay, and information on the types of data collected. More detailed information can be found in Pantin et al. (2022).https://publications.gc.ca/collections/collection_2023/mpo-dfo/fs70-5/Fs70-5-2022-076-eng.pdf
DFO Newfoundland and Labrador Region Inshore Trap Survey - Snow Crab 2018-2025
This data is from the Newfoundland and Labrador Region Inshore Trap survey, specific to Snow Crab from 2018-25, with only successful sets included in the database. Details of annual survey coverage and an overview of the survey program can be found in Pantin et al. (2025). This trap survey follows a depth-stratified random survey design, designated by type = 1 (Survey). Data were available from DFO inshore trap surveys in Fortune Bay, St. Mary’s Bay, Conception Bay, Trinity Bay, Bonavista Bay, Notre Dame Bay, White Bay, and infrequently along the Northeast Avalon Peninsula. All surveys follow a depth-stratified survey design with set locations randomly distributed within each stratum, and stratum-specific set allocations weighted by area. All surveys utilize large-mesh (5.25”) and small-mesh (42 mm) traps intermittently placed within each ‘fleet’ of gear, with traps spaced approximately 45 m (i.e., 25 fathoms) apart. Each fleet includes six baited traps, with two additional end traps not baited. Squid (Illex spp.) hung on skivers is attached to the inner entry cone of each trap as bait, with approximately 2–3 pounds of squid on each skiver. Although soak times are intended to be standardized to 24–48 hours, weather and other factors can affect the surveys and soak times are ultimately variable. Biological sampling is conducted at-sea from all traps at each station and is described in Pantin et al. (2025). Whole weights of Snow Crab are not always taken for every crab (e.g., in poor weather, missing limbs, carapace covered in biofouling) and those without measurements are denoted by an NA in the dataset. Analyses by the DFO NL Snow Crab group apply a length-weight relationship to determine weights, which is not in this dataset. Traps that caught zero Snow Crab are denoted in the dataset by a ‘number’ of 0.References:Pantin, J., D. Mullowney, K. Baker, K. Lefort, W. Coffey, F. Cyr, H. Munro, and Koen-Alonso, M. 2025. An Assessment of Newfoundland and Labrador Snow Crab (Chionoecetes opilio) in 2023. DFO. Can. Sci. Advis. Sec. Res. Doc. 2025/080. iv + 152 p.
Traditional knowledge of nearshore fisheries for the southern Gulf of St. Lawrence (1994-1997)
In 1998, Fisheries and Oceans Canada (DFO) published an atlas called "Traditional Fisheries Knowledge for the Southern Gulf of St. Lawrence". The document is composed of a series of maps that contain useful information primarily on nearshore fisheries and fish habitat in the eastern shore of New Brunswick, Prince Edward Island and the Gulf Shore of Nova Scotia. It was used as a working tool to assist in the development of integrated coastal zone management plans, resource management plans, and more.Between 1994 and 1997, data collectors and fishery officers interviewed local fishers and industry representatives. The purpose of these interviews was primarily to gain information on local fishing activities and the location of fisheries' resources and their habitats. The data and information was vetted through a process of verification with scientists, fishers, locals, industry representatives, and government officials. Maps were then compiled for 14 commercially important fish species and made publicly available to consult. These include lobster, rock crab, scallop, snow crab, toad crab, herring, mackerel, American plaice, cod, witch flounder (grey sole), hake, halibut, winter flounder, and unspecified groundfish. This data resource also includes the other 27 species originally not included in the atlas.
Geothermal Radiogenic Heat Production
Background:More than 80% of the heat produced in the Earth's crust comes from granitoid rocks. When granitoid rocks form they naturally concentrate radioactive elements such as U, Th, and K, and the radiogenic decay of these elements is an exothermic reaction. The radioactive decay of these elements within a granitoid body may generate local heat anomalies and elevated geothermal gradient at relatively shallow crustal levels. In combination with other local rock properties (e.g, porosity, permeability, thermal conductivity), radiogenic heat has the potential to generate a geothermal resource. The decay of radioactive elements converts mass into radiation energy, which in turn gets converted to heat. While all naturally radioactive isotopes generate some heat, significant heat generation only occurs from the decay of 238 U ,235 U ,232 Th and 40 K. Therefore, potential heat production is governed by the concentrations of U ,Th and K in the rock. In igneous rocks, radiogenic heat production is dependent on the bulk chemistry of the rock and decreases from acidic (e.g. granite) through basic to ultra basic rock types. Therefore, granites with anomalously high concentrations of U ,Th and K are targets for calculating potential radiogenic heat production. Potential radiogenic heat production (A)from plutonic rocks can be calculated using this equation:A (\\u03BCW/m 3 )=10 -5 \\u1D29 (9.52c u +2.56c K +3.48c Th )where "c" is the concentration of radioactive elements "U" and "Th" in ppm, and "K" in %; and "\\u1D29" is the rock density. Heat production constants of the natural radio-elements U, Th, K are 9.525x10 -5 , 2.561x10 -5 and 3.477x10 -9 W/kg, respectively.Data and Methods:Geochemical data from \~1760 samples of plutonic rocks from Yukon are used to calculate potential heat production. The calculated values for radiogenic heat production (A) are plotted over the mapped distribution of Paleozoic and younger plutonic rocks and major crustal faults are also shown for reference.
Tell us what you think!
GEO.ca is committed to open dialogue and community building around location-based issues and topics that matter to you.
Please send us your feedback