Trawl Catch and Species Abundance from the 2020 Gulf of Alaska International Year of the Salmon Expedition

Study Extent

A total of 52 trawls were conducted throughout the Gulf of Alaska between March 12 and April 6, 2020 as part of the International Year of the Salmon High Seas Expedition.

Sampling

To further improve the understanding of factors impacting salmon marine winter survival, a total of 52 trawls were conducted (codend mesh size: 3 mm). Of the trawls, 49 were midwater trawls and 3 were deep sets (headrope depth – 30 m). All salmon and bycatch species were processed immediately following each trawl. Total species-specific catch numbers and weight were recorded. Taxa were identified to the lowest taxonomic rank possible. For salmonids and the larger bycatch species the individual biometrics were recorded, such as length (fork, total, standard, mantle or bell diameter), wet weight, sex, and maturation stage, where possible. In addition, DNA samples, otoliths, muscle tissue, scales and live/gonad data of salmonids were collected for further analysis in Alaskan and UBC labs, however that data is not included in this data set. The data collected from the trawls aims to improve our understanding of the food web structure.

Method steps

1. All salmon and bycatch species were processed immediately following each trawl. Salmon and the larger species were enumerated, measured and weighed. Numerous samples were taken from each salmon: fin clips for genetic analysis; scales for ageing and growth rate; otoliths for ageing and early marine growth, checking for hatcheries marks and tags; muscles tissues for energy density, lipids, stable isotopes, fatty acid analyses and stomachs for diet analysis. Data users are encouraged to contact the data provider for data from these analyses.

Gulf of Alaska