Report to GFAA R

Report to GFAA R&D Foundation

2002 Cairns Black Marlin PAT Releases

John Gunn*, Toby Patterson*, Michael Domeier** and Julian Pepperell***

*CSIRO Marine Research

** Pfleger Institute for Environmental Research

*** Pepperell Consulting.

11 tags were released in October and November 2002 on fish ranging in size from 250-1100 lbs (estimated weight). These tags were sponsored by GFAA R&D Foundation (2 tags), Pfleger Institute of Environmental Research (7 tags) and Wildlife Computers (2 tags). The latter provided two PAT3 beta-test tags free of charge as part of their development of a new generation of PAT tags. CSIRO provided scientific support and travel costs for deployment free of charge to the project. Michael Domeier of the Pfleger Institute provided data and interpretations for the tags he had donated, and Julian Pepperell assisted with deployment free of charge.

As in previous years, fish were selected for release on the basis of apparent “healthy/vigorous” life status. The eleven included three fish that appeared healthy and vigorous, but had “thrown” their stomachs in the course of the fight.

At the time of writing this progress report, we have heard back from seven of the tags. The two Wildlife Computers PAT3 beta test tags failed to transmit, due to technical difficulties associated with the release pin (Wildlife Computers pers comm. 2003). One of the GFAA-sponsored tags (02PO552) is scheduled to pop-up 10 October 2003, and as we have not heard from this, we are hopeful that it may still be attached to a 1100lb female.

Table 1 provides a summary of the release details for each fish, and also a record of the fate of each tag/fish.

Observations from the data for tags that have transmitted are as follows:

· 3 of 9 tags recorded mortality in the fish. This included the first GFAA tag, released by Rebel. In this fish, mortality appears to have occurred very quickly after capture, after which it sank to the bottom (depth 480m), where it sat for 24 hours. The tag software is set to recognise inactivity (either on the bottom or the surface) so after 24 hours at one depth it popped off, floated to the surface and started transmitting. This fish and two of the other mortalities had thrown their stomachs during capture. Granted, a small sample size, but it appears that stomach throwing and rapid post-release mortality may be associated.

· A further 4 tags popped of prematurely, after times ranging from a few days to three months. As in previous years it is difficult to explain with any certainty why tags pop-off early. The most plausible explanations include tag failure (early breakage or corrosion of the release pins), release pin breakage through predation, or rejection of the tag anchor following intra-muscular placement of the anchors rather than placement between the pterygiophores of the second dorsal fin. Wildlife Computers are developing a sensor for the tag that will allow users to determine whether the release pin broke prior to pop-up, which will provide some clarity on these alternative explanations.

· One of the tags that shed early – after 3.5 months rather than 7 months, had travelled to Kirribas.

· Two tags that had released prematurely were later recovered on a North Queensland beach. The diving patters recorded by these tags were similar to those seen in earlier black marlin tags.

Acknowledgements.

Thanks go to the skippers, crews and anglers aboard the fishing vessels Top Shot, Mr Bill, Rebel, Mauna Kea and Reel Chase. Special mention is due to Peter B. Wright and Bob Lowe for their continued invaluable contributions to this research.

Codes
Mortality
shed before pop-up date
No report
Still to report back

BLACK MARLIN RELEASES OCTOBER 2002
Tag Owner	Tag Number	Tagging Date	Scheduled Pop-up	Release Time	Vessel	Estimated Weight	Release Lat	Release Lon	Pop-Up date	Pop-Up Lat	Pop-Up Lon
PIER	O2P0491	10-Oct-02	10-May-03	1530	TOP SHOT	800	15.20	145.48	1/17/2003	3.133N	164.679W
PIER	00P1040	11-Oct-02	10-May-03	1210	TOP SHOT	250	15.22	145.48	Still Deployed	-14.64	-144.21
PIER	01P0205	11-Oct-02	10-Mar-03	1305	TOP SHOT	400	15.19	145.47	20-Oct-02	-15.447	145.79
PIER	02P0490	17-Oct-02	10-Feb-03	1630	MR BILL	850	15.27	145.50	20-Oct-02	-16.69	146.53
WLC	02P0485	15-Oct-02	23-Oct-02	1307	MR BILL	650	15.28	145.50	?	?	?
WLC	02P0473	15-Oct-02	22-Oct-02	1345	MR BILL	450	15.28	145.50	?	?	?
GFAA	02P0543	13-Oct-02	10-Jan-03	1316	Rebel	500	14.42	145.42	01/19/02	-14.49	145.522
GFAA	02P0552	14-Oct-02	10-Oct-03	1334	Rebel	1100	14.39	145.42	Still Deployed	-13.35	-144.29
PIER	01P0189	16-Oct-02	09-Mar-03	1435	MAUNA KEA	450	14.41	145.41	24/10/2002	-14.714	145.76
PIER	01P0015	26-Oct-02	10-Mar-03	1725	REEL CHASE	900	15.20	145.48	27/10/2002	-16.955	146.256
PIER	01P0130	26-Oct-02	10-Mar-03	1520	REEL CHASE	750	15.19	145.47	07/11/2002	-20.389	152.825

Tag Owner	Tag Number	Comments
PIER	O2P0491	Caught by another vessel -unknown FT - circle hook
PIER	00P1040	Tag low -FT ~ 5 mins circle hook
PIER	01P0205	Stomach out ~ FT 10-15min circle hook
PIER	02P0490	Stomach out ~ FT 15-20min circle hook
WLC	02P0485	Stomach out circle hook
WLC	02P0473	Very lively circle hook
GFAA	02P0543	Tag low J hook, 71 min fight fish looked tired.
GFAA	02P0552	Stomach everted, 10 min fight, J hook, looked very good
PIER	01P0189	Circle hook
PIER	01P0015	Angler Tim Maddock, circle hook
PIER	01P0130	Angler - Chris Zidar, Circle Hook