USER_ID: Number for each person who created a profile to access the Scale age viewer application. Only project participants are included (7-13, 15-17). Reader_ID’s 1-7 correspond with USER_ID’s 7-13, and Reader_ID’s 8-10 correspond with USER_ID’s 15-17. USER_ID was used in all preliminary analysis.

fish.age: Sum of the freshwater- and saltwater age, is equal to the number of annuli on the scale, and it equal to the total age of the fish excluding the year in freshwater, estimated by a project participant. Fish ages had a minimum of 1 and a maximum of 7.

SYSTEM_CODE: Two letters corresponding to one of five Chinook salmon stocks in the study. ZA = Karluk, ZC = Copper, ZK = Kuskokwim, ZN = Nushagak, ZS = Stikine.

IMAGE_NAME: Image name that is an identifier for each of 10,200 images. Image names consist of 10 characters or all but one image that has a length of 11 characters. Characters one and two are the system code (see SYSTEM_CODE). Characters three and four are numbers and are the last two characters of the year sampled (i.e. a fish that was sampled in 2009 would have the characters “09”). Characters five and six represent the original fish age estimate in European notation without the decimal (the first character is the number of years spent rearing in fresh water after emergence from the gravel, the second characters is the number of years spent in salt water). Images for scales without an original age estimate have "00" for characters five and six. The seventh character is a letter representing sex of the fish, where F = female, M = male. The eighth, ninth, and tenth characters are numeric representing roughly consecutive numbering of images for each system, year, age, and sex and range from 000 to 100 for original images, and 992 through 999 for repeated images. One image has an eleventh character that is a 0, which can be ignored (image “ZN0913F1000”)

fish.age.EU: Fish age estimate for the scale of that IMAGE_NAME from project participant of a particular USER_ID. The field is numeric, with two characters representing the fish age, in European notation without the decimal (the first character is the number of years spent rearing in fresh water after emergence from the gravel, the second characters is the number of years spent in salt water). If the scale of that IMAGE_NAME was not readable for age in European notation by that USER_ID, the field is blank.

original.age.EU: Fish age estimate for the scale of that IMAGE_NAME from Alaska Department of Fish and Game personnel. The field is numeric, with two characters representing the fish age, in European notation without the decimal (the first character is the number of years spent rearing in fresh water after emergence from the gravel, the second characters is the number of years spent in salt water). If the scale of that IMAGE_NAME did not have an age estimate from that office, the field is blank. This field matches characters five and six of the IMAGE_NAME (except for images that did not have an original age that are "00" in the image name and blank in this field).

AGE_ERROR_CODE: Age error codes are a controlled list of numeric codes. If a project participant with USER_ID did not estimate the age of a fish from the scale image of a particular IMAGE_NAME, they selected one of these codes for a reason to not estimate age. Options are 3, 4, 6, 7, and 8. Code 3 = regenerated, 4 = illegible, 6 = resorbed, 7 = wrong species, and 8 = not preferred.

DATE_READ: Date that a project participant with USER_ID estimated the age or selected an error code for a particular scale IMAGE_NAME. Format is one or two character month, slash, one or two character day of month, and four character year.

COMMENTS: Field for project participant of a particular USER_ID to enter any sort of comment about the scale of that IMAGE_NAME. Most fields are empty and max length was 249 characters.

Reader_ID: Number for each person who participated in the project, starting with 1, ending with 10, and no gaps. Reader_ID’s 1-7 correspond with USER_ID’s 7-13, and Reader_ID’s 8-10 correspond with USER_ID’s 15-17. Reader ID is used in publications.