RREAS Survey Data

[mfeddern]

I let myself fall into a rabbit hole after class. Most years, Yelloweye are not caught in the core RREAS survey area (approx 36N to 38N). Digging into the data between 1990 - 2018 (I haven't pulled fully up to date data) there were only two years where Yelloweye were caught, 2015 and 2016 and there were only 13 observations where they were present and only 25 individuals total. In contrast to widow, which is one of the top 10 most abundant species, and were caught in 473 observations for a total of 7,800 individuals. Interestingly, yellowtail are pretty commonly caught so it may not be a latitude discrepancy.

From the coastwide YOY data, yelloweye are still less than 0.1% of the catch. Not sure what habitat and behavior differences drive it, but there is clearly not enough data for an index. John's 2021 paper goes into some good detail about the survey: https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0251638

[RebeccaMiller]

Hi Megan - it could possibly be timing of the survey itself. The RREAS better samples the winter spawning rockfish - where Widow release larvae around December and can be pelagic stage for 5 months (according to Milton Love's book), while Yelloweye larvae released a bit later --beginning around the March time frame. The RREAS samples in the late-April/May/mid-June time period.

Also - a question came up today in class about how the juvenile rockfish are identified on the survey -- Juvenile rockfish are initially identified at sea; and all samples are frozen, brought back to the lab and identifications are verified. Length measurements and otoliths are pulled for age reading in the lab

[mfeddern]

Thats a great point and I suspect it is what is going on. I was focused on latitudinal distribution but Yellowtail are fairly well sampled despite the population being located mostly north of 40 10'N. Thanks for sharing your biological insight!