This thread documents the discussion regarding macroscopic maturity assignments within ADF&G Groundfish Project.
In the March 4, 2021, NSEI sablefish assessment update meeting, Jane presented a figure showing 2019 and 2020 reduced maturity-at-age/length and asked if this was a sampling effect or something else.
Rhea looked into this issue and found that macroscopic maturity assignments and descriptions changed in 2016. Prior to 2016, the department had been using macroscopic maturity codes 1-6 to assign maturity to sablefish, see table below. This method classified codes 1 and 2 as immature fish, with code 2 encompassing sablefish that had not spawned before but will spawn in the coming year. Codes 3-6 were used to assign a value to mature fish. See Jane's maturity code assignments in the R code at the very bottom of this post.
Starting in 2016, the department switched to a binary macroscopic maturity assignment in which sablefish maturity was assigned as either 1-immature or 7-mature, see guide below. This change reclassifies the sablefish that had not spawned before but will spawn in the coming year from old maturity code 2 (immature) to new maturity code 7 (mature).
Jane, Rhea, Andrew, and Jake met on April 5, 2021, and discussed this change in maturity assignment for the first-time-spawners. It has been decided that these sablefish that have not yet spawned but will spawn in the coming year should be considered as mature.
As a result, it is important to note for historical comparisons using pre-/post-2016 maturity data, we expect to see a change in maturity-at-age/length as our maturity classification protocol has changed. This is particularly noticeable for years in which the large year classes enter into the spawning population (will spawn for first time in the coming year). Those fish that will spawn in the upcoming year were classified as "immature" in years prior to 2016 but are now classified as "mature" in 2016-present survey and port sampling data.
This thread documents the discussion regarding macroscopic maturity assignments within ADF&G Groundfish Project.
In the March 4, 2021, NSEI sablefish assessment update meeting, Jane presented a figure showing 2019 and 2020 reduced maturity-at-age/length and asked if this was a sampling effect or something else.
Rhea looked into this issue and found that macroscopic maturity assignments and descriptions changed in 2016. Prior to 2016, the department had been using macroscopic maturity codes 1-6 to assign maturity to sablefish, see table below. This method classified codes 1 and 2 as immature fish, with code 2 encompassing sablefish that had not spawned before but will spawn in the coming year. Codes 3-6 were used to assign a value to mature fish. See Jane's maturity code assignments in the R code at the very bottom of this post.
Starting in 2016, the department switched to a binary macroscopic maturity assignment in which sablefish maturity was assigned as either 1-immature or 7-mature, see guide below. This change reclassifies the sablefish that had not spawned before but will spawn in the coming year from old maturity code 2 (immature) to new maturity code 7 (mature).
Jane, Rhea, Andrew, and Jake met on April 5, 2021, and discussed this change in maturity assignment for the first-time-spawners. It has been decided that these sablefish that have not yet spawned but will spawn in the coming year should be considered as mature.
As a result, it is important to note for historical comparisons using pre-/post-2016 maturity data, we expect to see a change in maturity-at-age/length as our maturity classification protocol has changed. This is particularly noticeable for years in which the large year classes enter into the spawning population (will spawn for first time in the coming year). Those fish that will spawn in the upcoming year were classified as "immature" in years prior to 2016 but are now classified as "mature" in 2016-present survey and port sampling data.
Maturity code assignments in assessment: