Daniel B. Michrowski Terrance J. Quinn, II

University of Alaska, Fairbanks School of Fisheries and Ocean Sciences, Fisheries Division Juneau, AK

Wakefield Fisheries Symposium, May 2014

Background: 5 – “W’s” & How (much)

Methods – briefly

Injury categories

Influential factors

Take home message

Future efforts

The following presentation contains

graphic images and video of

injuries inflicted on skates as a

result of fisheries interactions. The

individual skates shown here may

or may not have survived… the

determination of which is the

whole point of this project!

Skates frequently caught and discarded by longline fleet • Usually alive with various injuries

Skates: k – selected, high trophic level predator/scavenger

Eastern Bering Sea shelf

Year-round since cooperative formed

27 000 mt caught in 2013 • Retention typically ~30%

Longline fleet: >70% of catch

0

20

40

60

80

Pacific cod -

longline

Misc.

flatfishes -

nonpelagic

trawl

Walleye

Pollock -

pelagic trawl

Other -

longline

Other -

nonpelagic

trawl

Catc

h (0

00

’s t

ons)

Target Species - Gear Type Observed skate catch 98-08 (Stevenson and Lewis, 2010)

100% mortality assumed • Precautionary approach

• Evidence of survival

• Previous injuries encountered at ~3%

Accurate fishing mortality rate necessary • Stock assessment

• Quota allocation

No standard handling protocol • Ripped off hook with gaff

• “Crucified”

• “Horned-off” or brush-bar

Careful handling techniques available

www.blueoceantackle.com; www.mustad-autoline.com

Discarded skates

Release method frequencies

45.3%

29.4%

19.2%

6.1%

Ripped

Crucified

Brush-bar

Other

n = 772

Data collection: two commercial vessel trips, National Marine Fisheries Service sablefish survey

Random systematic temporal sample frame •Collected from rail with pole-net or from fish trough

Four discrete injury severity categories •Skates ranked according to most severe injury

Parameters: Biological Fishing -Length -Handling method

-Disc width -Depth

-Weight -Crew member and experience

-Sex

-Species

Removal of one or both jaws

Tears to both sets of gills

Torn body cavity

Critical injury category “Jaws removed”

Torn jaw

musculature

Tear to one set of gills

Body cavity puncture with exposed organs

Extensive scavenger injuries

Deep pectoral tear

Broken jaw(s)

Tear to lower

mouth area and/or esophagus

Gill punctures Body cavity

puncture without organ exposure

Others

All other injuries, including: • Peripheral

punctures and tears

• Punctures to mouth area

• Tears in upper and side mouth areas

Injury category frequencies

14.9%

63.3%

14.7%

7.0%

Minor

Moderate

Severe

Critical

n = 911

Injury score by release method

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

Minor Moderate Severe Critical

Other

Brush-Bar

Ripped

Crucifier

n = 772

Multi-dimensional contingency tables

Tested independence of injury category and: • Release method and crew member experience

• Size and species

• Sex

• Depth

Data pooled due to low sample sizes

Release method and crew experience

(p < 0.001, n = 772) • Release method and injury score (p < 0.001)

• Crew experience and release method (p < 0.001)

Depth (p = 0.010, n = 772)

Size and species (p < 0.001, n = 911) • Confounding effects

• Includes pilot study

Injury categorization enables mortality estimates

Release method key parameter • Avenue to reduce mortality

Other parameters may be influential – significance requires further study

Further analysis of size and species effects • More sampling

Careful vs. Normal handling • Controlled on survey trip

Captive holding

Tagging

Major funding source: Pollock Conservation Cooperative Research Center Additional support: Freezer Longline Coalition

Advisor: Terry Quinn Committee members: Gordon Kruse, Jon Heifetz Sablefish survey team, Marine Ecology and Stock Assessment, Auke Bay Laboratories, NMFS

•Captain and crew of the F/V Ocean Prowler

Aleutian Spray Fisheries

•Captain and crew of the F/V US Liberator All the faculty, staff, and students at SFOS/UAF Family and friends Symposium hosts

Questions?