Tagging with Floy-T-bar and double tagging with DSTs and Floy-T-bar (MRI).

Key-words: Pleuronectes platessa, Plaice, DSTs, Floy-T-bar

Institute: Marine Research Institute, Iceland (MRI)

Contact (author): Jon Solmundsson

E-mail of contact: jonsol@hafro.is

Name of experiment: Migration pattern of plaice (Pleuronectes platessa) West of Iceland

Financial source: MRI

Annual cost (ECUs): IKR 1.500.000

Experiment began:1997

Experiment ends: 2001

Purpose of study:

Migration

Geographic distribution

Vertical movement

Mortality

Growth

Comparative tag recovery (verifying conventional tags):1

Species (Latin): Pleuronectes platessa

Common name: Plaice

Life stage: sub-adults, adults

Min size: 29 cm

Max size: 58 cm

Average size: 38 cm

Type of (primary) tag: Floy

Type of secondary tag (double tagging): DST

(Floy, Carlin, Torpeto, Stud, Microtag, Finclip, Dye,PIT, DST, Transmitting, etc.)

Site of attachment of (primary) tag: Body surface - right dorsal side

Site of attachment secondary tag (in double tagging): Body surface - right dorsal side

Method of attachment of (primary) tag: Tag gun

Method of attachment secondary tag (in double tagging): Tag gun, wire/thread

(Tag gun, syringe, surgical implant, plunger, wire/thread, etc.)

Tag release to environment: High seas, Shelf seas, Coastal seas

Tag rel location: Iceland-west, northwest

Number of tags released (mean/year, primary tag): 1800

General tag recovery rate (%/year): 25-45% after 1 year, 30-50% after 1.5 year.

Reward type: Money

Value of reward: Floy T-bar: IKR 1.000, DST: IKR 4.000

Reward currency: IKR

Short method description: A total of 8 tagging experiments at 6 locations west and northwest of Iceland. Plaice were tagged in the period between April 1997 and September 1998. A total of 4 experiments were carried out in 1997 including tagging of 2000 plaice with Floy T-Bar Anchor tags, and 4 experiments in 1998 including tagging of 1600 plaice with Floy tags and 160 plaice with both Floy tags and DST tags.

The plaice were captured by a seine net and kept in 500 L deck tanks with running seawater until tagging, 10 minutes to 2 hours later. The total length of tagged plaice was measured and the sex and maturity noted when possible. Concurrent to the tagging, measurements of length, weight, age, sex and maturity of plaice were made. All recoveries are through commercial fisheries. About 70% of recoveries include both tags and tagged fish.

The data storage tags (DST 300) were manufactured in 1998 by Star Oddi, Iceland. They are cylindrical, 13 mm in diameter, 46 mm in length, weight 1 g in water, have a memory of 8.100 measurements and were programmed to measure both depth (pressure) and temperature at specified time intervals for 6-12 months.

Tags were attached to the right dorsal side anterior to the widest part of the plaice. Two third of the DSTs were attached by inserting stainless silver wire (0.5 mm diameter) through temporarily inserted hollow needles. A silicon mat and the DST were then slipped over the wire. The wire ends were twisted together above the DST, leaving a slack of approximately 5 mm left in the wire to allow growth. Oval plastic plates were used to minimize erosion by the wire at the other side. One third of the DSTs were attached by shooting nylon double T-Bar Anchor attachments through loops at both ends on the DSTs, the tags reaching under the bones for a firm grip. A silicon mat was also fitted under those DSTs in order to protect the plaice.


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