Methods

Field

Best Practice

Example

Resource Lineage

Use this section of your metadata record to help future users understand how your dataset came to be. It is not uncommon for users to search for studies that employ a particular method (e.g., to conduct a meta-analysis of studies that use a particular technique), and this information will help them discover your work.

Describing your dataset’s methods in your metadata is similar to but different than writing the Methods section of a paper or report; you can think of your metadata methods section as a boiled-down, more concise version of the Methods section in your report. Bullet points that summarize your data collection process can work well, and be sure to mention and (where applicable) cite any specific methods you employed during your study.

Octopus were collected from commercial fishers during regular fishing operations targeting Pacific cod using pot gear. Octopus were assessed for condition and placed in tanks on board the fishing vessels. After a period of seventy two hours or less they were transported to the Kodiak Laboratory either via a tender vessel or the fishing vessel. Octopus were placed in individual tanks upon arrival at the laboratory. Within a 48 hour period a detailed assessment of the condition of each octopus was conducted, the gender of the octopus was determined, and each octopus was weighed. To weigh individual octopus, they were removed from their tanks, excess water was released from the mantle, and the octopus were weighed using standard bench top scales. Octopus were held for twenty one days; during this period they were fed herring to satiation two times per week. After 21 days, another detailed assessment was conducted. (Source: Discard mortality for the giant Pacific octopus in the Gulf of Alaska, 2014-15, NPRB Project 1203)

Process Steps

Use this field to describe anything that was done to your data between when it was recorded and when it was analyzed. Process Steps may include how raw data were converted, transformed, or otherwise prepared for your analysis.

Processing of the CTD data was done as per the manufacturer’s recommendations, with details of the processing steps documented in the metadata headers of the file. Processing was done with the following routines, from the SeaBird electronics SBE Data Processing software, and custom software written in MATLAB:

  1. Raw XML HEX data was copied to its own directory (xml), then converted to ASCII text with the ‘Data Conversion’ routine (SBE Data Processing).

  2. Data are low pass filtered to smooth out high frequency fluctuations with the ‘Filter’ routine (SBE Data Processing)

  3. Parameters are aligned in time with the ‘Align CTD’ routine (SBE Data Processing).

  4. Conductivity cell thermal mass effects are removed with a recursive filter with the ‘Cell Thermal Mass’ routine (SBE Data Processing)

  5. Derived values (salinity and seawater density) are calculated with the ‘Derive’ routine (SBE Data Processing)

  6. All data but the downcast (i.e. the surface soak and upcast) are cropped out, with a semi-automatic routine written in MATLAB. The routine allows the user to visually examine the depth profile of the cast, to select when the downcast begins and ends. Turbidity data is overlaid to allow removal of bottom touches.

  7. The native 16Hz data is converted to 1 m bins with ‘Bin Average’ (SBE Data Processing).

The files used in each processing step are stored in a separate directory, and each directory is prefaced with a number that indicates the processing step followed by text indicating what processing was done (1_cnv, 2_filter, 3_align, 4_CellTM, 5_derive, 6_crop, 7_bin). Data users will likely be most interested in the 6_crop and 7_bin directories. All relevant parameters used during the processing steps (e.g. constants used by filters, time delays used to align parameters, etc) are stored in the metadata of each file. In addition, the parameter files for all of the Seabird software are stored in a separate directory (psa). The Seabird .psa files are XML files (hence human readable) that store all the settings used by the software. (source: Environmental Drivers: Oceanographic Conditions in Prince William Sound, EVOS Gulf Watch)

Source Data

Use this field to cite any existing datasets that your project used. For some modeling projects, no data may actually be collected in the field, but one or may datasets may be obtained from other sources for analysis. In other cases, new data may be combined with old data to produce a new synthesis. In all cases, it is important to provide future users with all the information necessary to understand where your data came from and how to either access the same source data themselves (if the source is public) or request access to the data (if the source is private).

Source Title:

  • Eastern Bering Sea Tanner Crab Catch Data

Source Description:

  • Retained catch of males in the directed fishery for Eastern Bering Sea Tanner crab in mass (1000 metric tons, 1965-2012)

  • Discards of males and females in the directed fishery in mass (1000 metric tons, 1992-2012)

  • Discards of males and females in the groundfish fisheries of the Eastern Bering Sea (1000 metric tons, 1973-2012)

Source Citation:

  • Eastern Bering Sea Tanner crab: Stockhausen, W.T. 2015. 2015 Stock Assessment and Fishery Evaluation Report for the Tanner Crab Fisheries of the Bering Sea and Aleutian Islands Regions. In: 2015 Final Crab Stock Assessment and Fishery Evaluation Reports. North Pacific Fishery Management Council, Anchorage, AK, USA. pp 293-440.

Data Quality Reports

Use this field to describe any methods or techniques you used to ensure the completeness and accuracy of your data. For projects that employ specialized instruments, this would include calibration steps, either conducted by the manufacturer or yourself. For projects where data collection is by hand, either using data sheets or hand-held data loggers, this would include descriptions of the manual processed used to examined the data after they were collected.

Data Consistency Report:

Samples were processed by Auke Bay Laboratories according to standard operating procedures found in the file named Analysis of Petroleum Hydrocarbons SOP_May 2016 (Lindeberg, et al. 2017).

Lindeberg, M. R., M. G. Carls, J. Maselko. 2017. Lingering Oil: Extending the Tracking of Oil Levels and Weathering (PAH Composition) in PWS through Time. Restoration Project Final Report (Restoration Project 12120014-S), NOAA/NMFS Auke Bay Laboratories, Juneau, Alaska.

Quality assurance samples were processed with every 13 environmental samples and used to determine the acceptability of the data from each sample string. The quality assurance samples consisted of 2 reference material samples, 1 method blank, and 1 spiked blank and evaluate precision, method cleanliness and accuracy, respectively. See section 4 of Analysis of Petroleum Hydrocarbons SOP_May 2016.pdf for the composition of the QA samples.

A mid range calibration standard (calibration standard #3) was run near the middle and at the end of each string and used to evaluate calibration stability. The standards were analyzed as a sample and the results were reviewed for accuracy.