North Pacific Anadromous Fish Commission

Instructions for Sampling Salmon Tissues for DNA Stock Identification

NPAFC Working Group on Stock Identification

General Information

Genetic analysis is one of most reliable methods to estimate the population origins of salmon caught in the ocean. As of February 2017, species range-wide genetic baselines are available for chum, sockeye, and Chinook salmon.  Regional genetic baselines are available for pink and coho salmon, and steelhead will be available in the near future. Genetic analyses begin with tissue sample collection. This guide describes preferred and alternate methods using three approaches to collect samples from fresh or frozen salmon for DNA extraction.

How to Preserve DNA

In order to preserve DNA, the enzymes that break down the DNA must be inactivated. These enzymes need water to function, so it is very important to sequester water from the sample.

Preferred Tissue

  1. Axillary: Cut one axillary process from each salmon (Figs. 1, 2, and 3).
  2. Fin: Cut a piece of the fin (approximately 2 cm x 2 cm) from each salmon (Figs. 4 and 5).

Fig 1. Chinook Salmon. Image Credit: Salmon Fishing Now https://goo.gl/images/ihyzzB.
Figs. 2–5. Illustrations for sampling tissues from salmon for genetic analysis (photos: ADF&G).

Methods for Preserving Tissue

Below is a schematic of three approaches for preserving tissue, each one showing the preferred and alternate methods. Following this schematic are detailed descriptions for each method.

Freeze—Preferred: Individual samples in labeled vials

  1. Put individual tissue into a plastic vial labeled with a sample number (Fig. 1).
  2. Seal the vial with a screw cap (Fig. 2).
  3. Place whole group of samples in a plastic bag labeled with sample information (i.e., species name, date, location of collection, and any specific information for each fish; Fig. 3).
  4. Store the samples in freezer at -20°C or lower (Fig. 4).

Freeze—Alternate: Multiple samples in plastic food wrap and paper label

  1. Put individual tissue onto a piece paper.
  2. Write a label on a piece of paper (Fig. 1).
  3. Place paper with tissue onto a piece of plastic food wrap (Fig. 1).
  4. Roll the tissue and paper, in the plastic food wrap, one complete revolution (Fig. 2).
  5. Repeat steps 1, 2, 3, and 4 with remaining axillaries (Figs. 3 and 4).
  6. Place whole group of samples in a plastic bag labeled with sample information (i.e., species name, date, and location of collection, and any specific information for each fish; Fig. 5).
  7. Store the samples in freezer at -20°C or lower (Fig. 6).

Alcohol—Preferred: Individual samples in labeled vials with ethanol

  1. Put individual tissue into a plastic vial labeled with a sample number (Fig. 1).
  2. Fill vial with ethanol (Fig. 2).
  3. Seal the vial with a screw cap (Fig. 3).
  4. Place whole group of samples in a plastic bag labeled with sample information (i.e., species name, date, and location of collection, and any specific information for each fish; Fig. 4).
  5. Store the samples at room temperature.

Alcohol—Alternate: Multiple samples in high proof alcohol bottle

  1. Put axillaries into a bottle of high proof alcohol (example: Vodka) (Figs. 1 and 2).
  2. Put cap back on bottle (Fig. 3).
  3. Label bottle with sample information (i.e., species name, date, and location of collection; Fig. 4).
  4. Store the samples at room temperature.

Dry—Preferred: Attached to blotter paper in airtight case with desiccant packs

  1. Put individual tissue into a numbered square on the blotter paper sampling grid (Fig. 1).
  2. Staple the tissue sample to the paper (Fig. 2).
  3. Sprinkle non-iodized salt over tissues (Fig. 2).
  4. Write sample information at the top of each card (i.e., species name, date, location of collection, and any specific information for each fish).
  5. Place samples in airtight cases, with samples facing desiccant pack (Fig. 3 and 4).
  6. Seal container tightly (Fig. 5).
  7. Store at room temperature.

Dry—Alternate: Attached to regular paper and laid on vent in cabin to dry

  1. Place tissue on piece of paper (Fig. 1).
  2. Write sample number below sample (Fig. 2)
  3. Pour non-iodized salt over tissues (Fig. 3).
  4. Attach tissue to a piece of paper using tape or staple (Figs. 4 and 5).
  5. Put paper on warm vent (<500C) until completely dry (Fig. 6).
  6. Write collection information on the paper (i.e., species name, date, location of collection, and any specific information for each fish).
  7. Once dry, store group of samples and collection information in dry area (e.g., cabin, plastic bag, airtight box).

Contact Points for Sample Analysis

Canada

Eric Rondeau
Fisheries and Oceans Canada, Pacific Biological Station
3190 Hammond Bay Road, Nanaimo, B.C., V9T 6N7, Canada
Tel: 1-250-756-3351
E-mail: Eric.Rondeau@dfo-mpo.gc.ca

Japan

Shunpei Sato
Fisheries Resources and Ecology Division
Salmon Research Department
Fisheries Resources Institute (FRI)
Japan Fisheries Research and Education Agency
2-2 Nakanoshima, Toyohira-ku, Sapporo 062-0922, Japan
Tel: 81-11-822-2340
Fax: 81-11-814-7797
E-mail: sato_shunpei50@fra.go.jp

Korea

Ju Kyoung Kim
Aquatic Living Resources Center, East Sea Branch
Korea Fisheries Resources Agency (FIRA)
119 Dongmyeong-ro, Sonyang-myeon, Yangyang-gun
Gangwon-do 215-821, Republic of Korea
Tel: 82-33-670-1613
Fax: 82-33-671-0330
E-mail: logonkjk@fira.or.kr

Russia

Alexander Bugaev
Kamchatka Fishery and Oceanography Research Institute (KamchatNIRO)
18, Naberezhnaya Str. Petropavlovsk-Kamchatsky 683602, Russia
Tel: 7-4152-412-701
Fax: 7-4152-412-701
E-mail: Bugaev.A.V@kamniro.ru

USA

Chris Kondzela
National Marine Fisheries Service, Auke Bay Laboratory, Ted Stevens Marine Research Institute
17109 Point Lena Loop Road Juneau, AK 99801 USA
Tel: 1-907-789-6084
Fax: 1-907-789-6094
E-mail: Chris.Kondzela@noaa.gov

Sampling Instructions for DNA Stock Identification—Downloads

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