Gulf of Alaska Bottomfish

Author: Clay McKean (clay.mckean@alaska.gov)

Last updated: December 2024

Local Directory
There are 2 local directories associated with this project:
Homer: Main directory O:/DSF/GOAB/
Locally, this repository is housed at O:/DSF/GOAB/Git/
Anchorage Clay’s S:/DSFShared/Groundfish Port Sampling program/

About this project

This project assesses the halibut, rockfish, and lingcod sport fisheries in Southcentral Alaska by collecting biological samples and conducting angler interviews out of the ports of Homer, Seward, Whittier, Valdez, and Kodiak.
The operational plan for this project can be found here: https://www.adfg.alaska.gov/FedAidPDFs/ROP.SF.2A.2022.24.pdf

Project Objectives

Primary Objectives

1. Estimate the mean weight of Pacific halibut taken by each user in each area of Southcentral Alaska (Kodiak, Lower Cook Inlet, Central Cook Inlet, North Gulf Coast, Eastern Prince William Sound, and Western Prince William Sound), such that the mean weight estimates for each user group in each area are within 0.20 of the true mean weight at least 90% of the time.
2. Estimate the length composition of the Pacific halibut harvest by area such that the estimated proportions are within 0.20 of the true proportions at least 95% of the time.
3. Estimate the species composition by port of the rockfish harvest landed at Kodiak, Homer, Seward, Whittier, and Valdez during May through September such that the estimated proportions of each species are within 0.20 of the true proportions at least 95% of the time.
4. Estimate the age, length, and sex composition by port of the principal rockfishes landed at Kodiak, Homer, Seward, Whittier, and Valdez during May through September such that the estimated proportions are within 0.20 of the true proportions at least 95% of the time.
5. Estimate the age, length, and sex composition by port of the lingcod harvest landed at Kodiak, Homer, Seward, Whittier, and Valdez during July through September such that the estimated proportions are within 0.20 of the true proportions at least 90% of the time.

Secondary Objectives

1. Identify differences in the geographic distribution of groundfish effort and harvest between user groups and across years for each port during May through September.
2. Estimate the proportion of the Pacific halibut harvest that was cleaned (and carcasses discarded) at sea at each port. These estimates will be used to stratify length and weight estimates at ports where cleaning at sea is prevalent.
3. Estimate the proportions of released Pacific halibut that were caught on circle hooks versus other types of hooks at each port. This information is needed to refine estimates of halibut release mortality in the sport fishery.
4. To refine discard mortality estimates, gather data on the depths of capture for pelagic and nonpelagic rockfish that were released.
5. Estimate the proportions of released lingcod that were of sublegal (under 35 inches total length) and legal size (35 inches and greater) for ports with a minimum size limit regulation. These data will provide information on future recruitment and abundance indices used for future stock assessments.
6. Biological data will be collected from salmon sharks (Lamna ditropis), Pacific sleeper sharks (Somniosus pacificus), and spiny dogfish (Squalus acanthias) harvested in the sport fishery in order to estimate the age, length, sex composition, and spatial distribution of the harvest. No sampling objectives are established for sharks because harvests are too small to generate reliable estimates for any given year. It is expected that age, length, and sex data will be compiled across a number of years and combined with commercial harvest sampling and other research programs to estimate life history parameters.

Repository Directory

• 1.data/: Data folder

  • i.HAL/: Halibut AWL data. Data is compiled each year from port sampling biological samples
  • ii.Harvest/: Rockfish and Lingcod harvest data, calculated by combining SWHS and logbook estimates
    • a.LC/: Lingcod harvest data by port and sport fish management area
    • b.RF/: Rockfish harvest data by port, sport fish management area, and species
  • iii.Intervw/: Port sampling interview data. Data is compiled each year from interview samples
  • iv.LC/: Lingcod AWL data. Data is compiled each year from port sampling biological samples
  • v.RF/: Rockfish AWL data. Data is compiled each year from port sampling biological samples
  • vi.RF_Harvest_Reconstruction/: Statewide rockfish harvest and release estimates using the Howard et al. method. This data is used for the annual rockfish harvest reconstruction. 
    • This data comes from Phil Joy, and can be found at https://github.com/ADFG-DSF/RockfishSportMort/output/

• 2.Figures/: Output figures

• 3.reports/: Reports associated with this repository

  • i.RF_Harvest_Reconstruction.R: This file contains the output file of the rockfish harvest reconstruction, titled RF_Removals_thruXX.xlsx. This file is sent out to the members of the Statewide Rockfish Initiative in early October, once the harvest and release estimates are recieved from Phil Joy.

• 4.scripts/: Scripts for running analyses

  • i.Age_comps/: Age composition data for Rockfish and Lingcod
    • a.LC Age Comp bubble.R: Lingcod age composition bubble plot
    • b.LCAgeComp9622_port.R: Lingcod age composition by port
    • c.LCAgeComp9622_SFmgmtarea.R: Lingcod age composition by sport fish management area
    • d.RF Age Comp bubble.R: Rockfish age composition bubble plot
    • b.RFAgeComp9622_port.R: Rockfish age composition by port
    • c.RFAgeComp9622_SFmgmtarea.R: Rockfish age composition by sport fish management area
  • ii.Apportionment/: Apportioning groundfish to sport fish management areas to assess proportion of harvest by port and management area
    • a.Apportion halibut to mgmtareas.R: Halibut apportionment
    • b.Apportion lingcod to mgmtareas.R: Lingcod apportionment
    • c.Apportion rockfish to mgmtareas.R: Rockfish apportionment
  • iii.L.WRegression/: Calculate yield of groundfish in kg, using length-weight regressions to estimate weights of fish when no weight is available in the data.  Computation is based on the basic formula: Yield(s) = Harvest(all s) * SpeciesComp(s) * MeanWt(s).
    Estimates are preliminary because they are based on L-W regressions that haven’t yet been tested for differences between years, ports, sexes, etc.
    • a.LCYieldPrelim_SFmgmtarea.R: Estimate of lingcod yield by sport fish management area by year
    • b.RFYieldPrelim_byAssemb_port.R: Estimate of rockfish yield by port and assemblage by year
    • c.RFYieldPrelim_byAssemb_SFmgmtarea.R: Estimate of rockfish yield by sport fish management area and assemblage by year
  • iv.RF_Reconstruction: Rockfish harvest reconstruction using harvest and release estimates from RTS.
    • a.RF_removals: Estimates the total removals in lbs. for Black and Yelloweye rockfish using harvest and release estimates from Phil Joy, using the Howard et al. method. This script should be run in early October after recieving the updated harvest and release estimates. Be sure to update the script to add the port sampling data for the current year and update the ouput file to state the current year.
  • v.Spatial harvest and effort/: Total harvest by port, user, and year from port sampling interview data. Used for providing harvest trends in managemnet reports/
    • a.LC/: Lingcod data/
      • (i).LC_report_spatial_subset.R: Lingcod interview harvest data for lingcod report/
    • b.RF/: Rockfish data. currently empty/
  • vi.Species_comp/: Rockfish species composition data from port sampling biological sampling/
    • a.RF by assemblage.R: Species compositon and average weights per year at the assemblage level. Predicted weights based on length used when weight is not available for a sample/
    • b.RF_simple_spcomp.R: Simple species composition by sport fish management area. Useful for providing species comps to area managers
    • c.RFspcomp9622.R: Rockfish species composition in biological data. Uses Steve Fleischman version of composition equations
  • vii.AWLsummaries.R: Summary statistics of rockfish data. For rockfish report
  • viii.FractionCleanedAtSea.R: Calculates the fraction of harvest cleaned at sea by port for halibut, rockfish, and lingcod. Used in writing Op plan.

• 5.functions.R: Functions used in R scripts. Accessed with source("functions.R")