Post-release Survival of Blue Marlin

Mike Musyl, Chris Moyes, Rich Brill, Andrew West

John Sibert, Anders Nielsen, & Lianne McNaughton

Our goals were:

1. Assess the survival blue marlin released from sports fishing.

2. Develop biochemical predictors of survival.

3. Assess factors affecting post-release survival.

PSATs can be used to determine mortality by examination of vertical data.

PSATs jettison from fish under three circumstances:

1. Reach programmed pop-off date.

2. Exceed depth threshold (1200 – 1500 m).

3. Remain at constant depth for 4 days.

Can differentiate “dead” from “shed”.

Mortality of a Blue Shark (Prionace glauca)

1124m

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12004/11/01 4/12/01 4/12/01 4/14/01 4/14/01 4/14/01 4/16/01

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Depth (m) Temperature (oC)

Fail safe mechanism jettisons PSAT after reaching 1200m

Swivel to reduce torque of tag head in tissue

Speargun barbs added to increase surface area

37 blue marlin (100-500 lbs) tagged in Hawaii

2 striped marlin (120 lb) tagged in Hawaii

1 black marlin (1000 lb) tagged in Australia

fight times: 5 - 60 min

16% on bait, 84% on lures

PSAT

12

64

2140

Total Days at Liberty

1(100%)

1(100%)

28(78%)

No. Reporting(%)

12

64

76(1-245)

Mean(Range)

2*1

Striped Marlin(Tetrapturus audax)

1Black Marlin (Makaira indicus)

37*1

Blue Marlin (Makaira nigricans)

Number Tagged *No. Waiting

Species

Results to date

30 tags reported data (79%)

8 tags failed to report (21%)

4 tags reached pop-off date (13%)

Evidence for delayed mortality in one blue marlin

Blue marlin movement patterns

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2007/24/2003

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0:007/26/2003

0:007/27/2003

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Hawaii Standard Time

Dept

h(m

)Full MoonFirst Quarter

Hourly Depth Preferences

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14:00 17:00 20:00 23:00 2:00 5:00 8:00 11:00Hawaii Standard Time

Avg.

Dep

th(m

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First Quarter New Moon

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Dept

h(m)

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Temp

(o C)

Full Moon

Perc

ent o

f Tot

al T

ime

Blue MarlinStriped MarlinBlack Marlin

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100

0102030405060708090

100

10.5-50 50.5-100 100.5-150 150.5-250 250.5-350

Night

Depth (m)

Day Time at depth summaries

Depth distribution of blue marlin tracked near Hawaii using acoustic telemetry.

Depth distribution of blue marlin tracked near Hawaii using acoustic telemetry.

0102030405060708090

100

0102030405060708090

100

10.5-50 50.5-100 100.5-150 150.5-250 250.5-350

Night

Depth (m)

Day

Day

Night

Blue marlin movement patterns

Evidence for delayed mortality in Blue marlin after 82 days

Deployed

7 June 2003

Pop-off

29 September 2003

Caught on live bait

Approx. 25 minutes of fight time

130 lb monofilament test line

Hooked corner mouth

Moved almost due South 855 nmi (7.6 nmi /day)

0200400600800

10001200

7/7 7/17 7/27 8/6 8/16 8/26 9/5 9/15 9/2505101520253035

Max. Depth (m) SST Min. Temp.

Fail safe mechanism jettisons PSAT after reaching 1200m

Evidence for delayed mortality in Blue marlin after 82 days

SummarySummary

• 29 of the 30 tags reporting data indicate post-release survival (i.e., only one mortality).

• Fail-safe mechanism worked as expected.

• Unlikely that mortality after 82 days was the result of the initial insult.

Previous studies investigating post-release survivability

in marlin using PSATs

Graves et al. 2002. Fish. Bull. 100:134-142.

• 9 blue marlin tagged in Atlantic

• Estimated sizes: 150- 425 lbs.

• Caught marlin on lures and bait

• Pop-off times set at 5 days

• 8 survived

• Fate of one tag unknown

• No evidence of mortality

Kerstetter et al. 2003. Fish. Bull. 101: 939-948

9 blue marlin tagged in Atlantic

Estimated sizes: > 100 lbs.

Caught on longlines

Pop-off times set at 5-30 days

7 survived

Fate of two tags unknown

No evidence of mortality

Gunn et al. 2003. Mar. FW Res. 54: 515-525

• 7 black marlin tagged in Coral Sea• Estimated sizes: 200-600 lbs.• Caught on live and dead bait• Variable pop-off dates (4 days – 5 months)• 5 of 7 survived for 3 – 64 days• Fate of 2 tags was unknown• No evidence of mortality

Domeier et al. 2003. Mar. FW Res. 54: 435-445

• 80 striped marlin tagged near Baja California• Estimated sizes: 90-188 lbs • Caught on live bait using circle & J-hooks

• 45 fish survived • 16 of 61 fish (26%) died within 5 days

• Fate of 19 tags unknown

Blue marlin show a huge increase in blood lactate

Lactate Hsp70 mRNA0

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Blue shark Blue marlin

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Lowest marlin lactate is close to the highest shark lactate level

Survivor Moribund Unknown

Mahalo’s to:

•Jody Bright & Crew of Tropidilla Productions

•Roy Morioka, PORF, HIBT

•Peter Fithian, PORF, HIBT

•John Sibert, PFRP

•Pacific Islands Fisheries Science Center

•Chris Boggs, Mike Laurs, Sam Pooley, NOAA

•CABO Yachts

and the Captains and Crew who Deployed PSATs:

Camelot Foxy Lady

Happy Times Holly Ann

Ho’okele Ihu Nui

Jacque Apito Linda Sue

Maui Jim Pacific Blue

Pamela Start Me Up Again

Top Shape

Blue sharks Four parameters show clear differs between

survivors & moribund

0

0.5

1.0

1.5

2.0

Survivor Moribund Unknown

K+ Mg2+

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Lactate Hsp70 mRNA

K+ shows much greater increases in marlin

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K+ Mg2+

Blue sharkMg+ increases ~50%

Blue marlinMg+ increases ~400%

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10152025303540

Survivor Moribund Unknown

Blue marlin show greater Hsp70 induction

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Lactate Hsp70 mRNA

Blue sharkHsp70 increases ~3-fold

Blue marlinHsp70 increases > 5-fold

Black marlin movement pattern