Days at Large. Distance (nm)

Transcription

1 Thanks to the generous support of the Mohammedia Blue and White Billfish Tournament, white marlin joined the IGFA Great Marlin Race (IGMR) along with blue marlin, black marlin, and sailfish. With their abundance in severe decline from decades of commercial overfishing, white marlin may be one of the world s most imperiled species of billfish. The data collected during the 2013 Mohammedia, Morocco IGMR is helping us to understand more about white marlin migration and vertical habitat patterns and will hopefully provide scientists and managers with the information they need to better protect this important species. The Mohammedia Blue and White Billfish Tournament was held September 8-13, 2014 in Mohammedia, Morocco where 14 teams from countries as far as Russia, Senegal, Ivory Coast, France, and Germany competed to see which team could catch and release the most white marlin. Thanks to the direction of IGFA representative Fouad Sahiaoui, five mini Popup Archival Satellite Transmitting (minipat) tags and one larger MK10 tag were sponsored for deployment during and after the tournament. During the second day of the tournament, on September 9, 2013, IGFA Conservation Director Jason Schratwieser placed the first tag of the race (Tag 11P0344) on a 32 kg (70 lb) white marlin that fought for 15 minutes with angler Christian Galtier aboard Gladius. The tag was generously sponsored by Fouad Sahiaoui. The second tag deployed in the race (Tag 11P0725) was sponsored by Laurent Sahyoun and sent off September 11, 2013 on a 34 kg (75 lb) white marlin, from Gladius. The third satellite tag (Tag 11P0726), sponsored by Roger Sayhoun, was deployed the following morning of September 12, 2013, on a 32 kg (70 lb) white marlin after a 15 minute fight with angler Yann Renault aboard Gladius. Brahim El Ouafi sponsored the fourth satellite tag in the race (Tag 11P0829) and one month later, on October 12, 2013, Fouad Sahiaoui placed the tag on a 37 kg (82 lb) white marlin that he caught after a 25 minute fight aboard Gladius. In the same afternoon and on the same boat, Fouad Sahiaoui placed an MK-10 tag (Tag 11A0605), the fifth tag in the race, on a 34 kg (75 lb) white marlin, which put up a 20 minute

2 bout with angler Brahim El Ouafi. This tag was the only MK-10 tag deployed in this event, and was generously co-sponsored by Mohammed Filali, Karim Bensoltana, and Hakim Moncef. Roughly an hour later, Fouad Sahiaoui caught and placed the sixth tag in the race (Tag 11P0722) on a 42 kg (93 lb) white marlin. The tag was generously sponsored by Mohammed Rayad. TAG Boat Fish Tagged Reported Days at Large Distance (nm) Est. Wt. (lbs) Est. Wt. (kg) Angler Tagger 11P0344 Gladius 1 9/9/2013 3/8/ , Christian Galtier Jason Schratwieser 11P0725 Gladius 2 9/11/2013 9/22/ Jason Schratwieser Jason Schratwieser 11P0726 Gladius 3 9/12/ /12/ Yann Renault Jason Schratwieser 11P0829 Gladius 4 10/12/ /13/ Fouad Sahiaoui Fouad Sahiaoui 11A0605 Gladius 5 10/12/2013 1/23/ , Brahim El Ouafi Fouad Sahiaoui 11P0722 Gladius 6 10/12/ /24/ Fouad Sahiaoui Fouad Sahiaoui We are pleased to report that all six tags placed on white marlin in the Mohammedia, Morocco 2013 IGMR successfully reported. The tag on Fish 2 (Tag 11P0725) was the first to surface on September 22, 2013 and reported 22 nautical miles (nm) from where it was deployed after 11 days at large. Examination of the data indicated that the marlin perished within the first 24 hours after being tagged, and sunk to a depth of approximately 152 meters (m), where it remained before the tag released itself from the carcass and floated to the surface (as it is programmed to do). Unfortunately, Fish 2 earned last place in the race and a track cannot be generated for this deployment. On October 12, 2013, the tag on Fish 3 (Tag 11P0726) reported just off the coast of Western Sahara. The marlin swam 691 nm, which is quite a far distance in only 30 days! This distance earned Fish 3 fourth place in the race. One month later, on November 13, 2013, Fish 4 s tag (Tag 11P0829) surfaced off the southern coast of Western Sahara. The fish traveled a point to point distance of 982 nm in 32 days, and finished in third place in the race. Nearly two weeks later, the tag on Fish 6 (Tag 11P0722) reported on November 24, 2013, after 43 days at liberty. The white swam 480 nm west and almost reached the Strait of Gibraltar. Fish 6 earned fifth place in the race. On January 23, 2014, Fish 5 s tag (Tag 11A0605) surfaced off the coast of the Cape Verde Islands. The fish swam a remarkable distance of 1,336 nm in 103 days, and finished in second place in the race. On March 8, 2014, the final tag in the Mohammedia, Morocco 2013 IGMR surfaced to win the race after remaining on Fish 1 for the full programmed duration of 180 days. The tag reported about 100 miles off the southern coast of Senegal, at a distance of 1,412 nm from

3 where it was deployed. Congratulations to IGFA Representative Fouad Sahiaoui for sponsoring the winning tag! Figure 1. Map of the final results for the Mohammedia, Morocco 2013 IGFA Great Marlin Race. The race was won by Fish 1 (11P0344, orange), with Fish 5 (11A0605, yellow) coming in close second. Fish 4 (11P0898, green) came in third place; Fish 3 (11P0726, purple) in fourth place; Fish 6 (11P0722, white) in fifth place. The Mohammedia, Morocco 2013 IGFA Great Marlin Race holds a special place in the history of the IGMR because it is the first competition where white marlin were tagged. Due to the relatively small size of white marlin, there was some question about how well the marlin would carry the satellite tags. The results were encouraging; four marlin traveled considerable distances (Tags 11P0344, 11P0726, 11P0829, 11A0605) and only one tagging mortality occurred (Tag 11P0725). The early tag releases are of some concern, but are not unique to this event. Of the five tags where tracks were created, four marlin traveled south-southwest (Tags 11P0344, 11P0726, 11P0829, 11A0605), although there was great variation in the distances of their tracks from the west coast of Africa. It is worth noting that the one marlin that swam west-northwest (Tag 11P0722) followed roughly the same course as three of the other marlin that ultimately turned to the south-southwest (Tags 11P0344, 11P0829, 11A0605), suggesting that the fish may have been on a similar trajectory before its tag prematurely released.

4 All of the marlin swam fairly quickly following their initial release. The two marlin that traveled the furthest (Tags 11P0344 and 11A0605) slowed down only after they reached the coasts of Senegal and the Cape Verde islands where their tracks became more tortuous, possibly indicating foraging behavior. The white marlin tagged in this event spent more time in cooler water than the blue and black marlin tagged in other IGMR events, with the exception of the blue marlin tagged in the Canary Islands and Madeira, who exhibited similar temperature distributions. When comparing the five white marlin that were tracked in this event with the blue marlin tagged during events in the same area, we noticed that all of the marlin spent the bulk of their time in water temperatures between C (72-75 F), as opposed to blue and black marlin in other parts of the globe who preferred warmer temperatures between C (79-82 F). Although the temperature distributions of white and blue marlin in the eastern Atlantic are similar, their depth distributions are more distinct. The white marlin exhibited a more shallow distribution than the blues, and they did not dive as deeply. This observation fosters the possibility that the ability to exploit colder, deeper habitats may play a role in niche partitioning between blue marlin and white marlin, who seem to spend more time in warmer, shallower waters. Insights such as these are what make the IGFA Great Marlin Race program so exciting, and we hope that we can continue to increase our knowledge of these majestic animals. We are thankful for the generous support from the tournament organizers, anglers, captains, and crew members involved in the Mohammedia Blue and White Billfish, without whom, this event would not have been possible.

5 Tag 11P0344 Fish 1 Tag number: 11P0344 Sponsor: Fouad Sahiaoui Angler: Christian Galtier Tagger: Jason Schratwieser Estimated weight: 32 kg Deployed: 9/9/2013 Reported: 3/8/2014 Days at large: 180 Distance traveled: 1,412 nm Maximum depth: 336 m Minimum temp: 11.8 C Maximum temp: 26.4 C

6 Tag 11P0725 Fish 2 Tag number: 11P0725 Sponsor: Laurent Sahyoun Angler: Jason Schratwieser Tagger: Jason Schratwieser Estimated weight: 34 kg Deployed: 9/11/2013 Reported: 9/22/2013 Days at large: 11 Distance traveled: 22 nm Maximum depth: 152 m Minimum temp: 14.8 C Maximum temp: 23.4 C

7 Tag 11P0726 Fish 3 Tag number: 11P0726 Sponsor: Roger Sahyoun Angler: Yann Renault Tagger: Jason Schratwieser Estimated weight: 32 kg Deployed: 9/12/2013 Reported: 10/12/2014 Days at large: 30 Distance traveled: 691 nm Maximum depth: 272 m Minimum temp: 14.4 C Maximum temp: 24.6 C

8 Tag 11P0829 Fish 4 Tag number: 11P0829 Sponsor: Brahim El Ouafi Angler: Fouad Sahiaoui Tagger: Fouad Sahiaoui Estimated weight: 37 kg Deployed: 10/12/2013 Reported: 11/13/2014 Days at large: 32 Distance traveled: 982 nm Maximum depth: 208 m Minimum temp: 14.8 C Maximum temp: 24.4 C

9 Tag 11A0605 Fish 5 Tag number: 11A0605 Sponsor: Mohammed Filali, Karim Bensoltana, Hakim Moncef Angler: Brahim El Ouafi Tagger: Fouad Sahiaoui Estimated weight: 34 kg Deployed: 10/12/2013 Reported: 1/23/2014 Days at large: 103 Distance traveled: 1,336 nm Maximum depth: 584 m Minimum temp: 9.0 C Maximum temp: 28.0 C

10 Tag 11P0722 Fish 6 Tag number: 11P0722 Sponsor: Mohammed Rayad Angler: Fouad Sahiaoui Tagger: Fouad Sahiaoui Estimated weight: 42 kg Deployed: 10/12/2013 Reported: 11/24/2013 Days at large: 43 Distance traveled: 480 nm Maximum depth: 248 m Minimum temp: 13.6 C Maximum temp: 23.4 C