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IPHC News Release 2018-014 IPHC Pacific Halibut Tagging Studies

18 June 2018

PACIFIC HALIBUT TAGGING STUDIES

In 2018 the International Pacific Halibut Commission (IPHC) will be continuing tagging efforts with the aim of obtaining valuable information on migration, dispersal, and the effects of thermal history on growth in Pacific halibut.

The IPHC is asking fishers and processors to look for tagged Pacific halibut and, if possible, to leave the tag on the fish until examined by staff from the IPHC Secretariat or a federal observer. New and ongoing tagging studies in 2018 are described below.

2018 Electronic tagging to study juvenile growth and migration (new)

The IPHC will tag 327 Pacific halibut smaller than the commercial minimm size limit (<32 inches [81.3 cm], or “U32”) with electronic archival tags in 2018. These tags, which record temperature, depth, and light levels, will be deployed during this year’s fishery-independent setline survey at a number of locations across the Convention Area. Two types will be deployed, both of which will be attached to the fish’s dark side using a dart-and-tether arrangement. Most will be small (~5 cms [2 in]) and remain on the fish until recaptured (illustrated in Fig. 1); the remainder will be larger “pop-up” tags which release from the tether at a pre-programmed date (Fig. 2). The data will be used to relate temperature to growth and size at age, and to relate light and depth to migrations and seasonal movement. An additional goal is to link otolith (“earbone”) chemistry to temperature so that the IPHC can extend the analyses to untagged fish that are sampled in the commercial catch. It is therefore very important to recover the otoliths from the tagged fish as well as the tag recovery information.

For this reason, rewards for the recovery of these electronic tags will range from $300 to $500, depending on how much information can be provided to the IPHC upon recapture, as follows:

$300: Electronic tag is returned with information regarding the length of the fish and recapture location.

$400: Electronic tag is returned along with the otoliths, fish length, and recapture location.

$500: Whole fish and electronic tag are presented to an IPHC port sampler, allowing the sampler to collect the tag, recovery information, otoliths, and other biological samples.

2018 Wire tagging of U32 Pacific halibut (ongoing since 2015)

This is the fourth year of wire-tagging U32 Pacific halibut with the goal of gaining insight into movement and growth of younger Pacific halibut. Many of these fish are likely to be caught by trawl gear. The plastic-coated wire tags are various colors, marked with IPHC contact information and tag number, and attached to the dark side cheek area (Fig. 3).

A subset of these fish, tagged with orange tags with the text “PLEASE PHOTOGRAPH TAIL,” are part of a study investigating whether pigmentation patterns on the white side of the tail persist through life and can therefore be used as a natural tag. The IPHC would like fishers and processors encounterning these tags to photograph the tail on the white side (example in Fig. 4) and provide the photo along with the tag and associated recovery information to an IPHC port sampler or the IPHC’s Seattle office.

Fig 1 and 2

Instructions for recovered tags

Tagged Pacific halibut of any size may be retained from any gear or fishery, whether or not the fisher holds Pacific halibut quota, and at any time of year, although undersized fish may not be sold.

Leave the tag(s) attached to the fish and report the capture at time of landing to an IPHC port sampler, other agency fishery sampler, or contact the IPHC Seattle office at (206) 634-1838. IPHC has samplers in Dutch Harbor, Kodiak, Homer, Seward, Sitka, Juneau, and Petersburg, AK, as well as Prince Rupert and Port Hardy, BC, throughout the commercial halibut season, and in St. Paul, AK, during July and August.

If you catch a tagged Pacific halibut, and are landing in a port not staffed by an IPHC employee or other agency fish sampler, please return the tag with the following information: recovery date and location, fish length, sex, otoliths, and finder’s name and address to the IPHC’s Seattle office at the following address:

2320 West Commodore Way, Suite 300, Seattle, WA 98199, USA

2018 Tag rewards

A reward is paid for all IPHC tags. The reward amount depends on the tag type and, in some cases, the reward is also dependent on the data returned with the tag. The standard reward for an IPHC tag is a baseball cap, knit cap, or $10. Electronic tags have higher-value reward amounts, ranging between $100 and $500, and have the reward amount printed on the tag. The metal dart and leader assembly from pop-up tags is rewarded at $50. Wire tags bearing the text “PLEASE PHOTOGRAPH TAIL” will be redeemed at $20 or two hats if both the tag and a photo of the white side tail are returned; if only the tag is returned, the standard reward applies.

More information on Pacific halibut tagging studies can be found on the IPHC website: https://iphc.int/management/science-and-research/biological-and-ecosystem-science-research-program-bandesrp/bandesrp-migration/tagging. Tag-related questions can also be directed to secretariat@iphc.int.

ONGOING SUBSCRIPTION TO IPHC NEWS RELEASES

Dear Reader: The IPHC is moving towards fully electronic information distribution. As such, if you would like to continue to receive IPHC news in the future, please click the following link to subscribe: https://iphc.int/form/news-letter. Hard copies of news releases and similar bulletins will cease in the coming months.

David T. Wilson, Ph.D.
Executive Director, IPHC
Phone: (206) 634-1838
Fax:     (206) 632-2983
Web:  iphc.int

Document Title PDF Link Date Published
IPHC-2018-NR014 IPHC Pacific halibut tagging studies

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18 June 2018