Adriatic Expedition

Personnel And Acknowledgements

Organisers - Shark Conservation Society

Leader - Richard Peirce

Logistics, medical & catering director - Jacqueline Peirce

Skipper - Vlado

Volunteer researchers - Andy Sweeney, Karen Wilson, Sait Ozgur Gedikoglu, Ken Neal.

Documentary film crew - Sait Ozgur Gedikoglu, Richard Peirce.

The Society would like to thank

• Alen Soldo
• Denis Klarin
• Vlado, Nada, and Christina.

Introduction

At the end of the 2005 SCS Adriatic shark search expedition Alen Soldo mentioned the possibility of the area offshore Dugi Otok/Mana islands being a pupping ground and nursery area for Blue sharks.

The area was not extensively investigated during the 2005 or 2006 surveys, however nine hours and fifty minutes chumming of the site on August 7th 2005 produced one line caught Blue shark near natal pup of 60cms which was successfully tagged and released.

In October 2009 the third SCS Adriatic expedition returned to the site to specifically investigate the pupping ground/nursery possibility.

Investigation

The Jazera vessel Eudi was chartered and a team of six SCS volunteers led by SCS Chairman Richard Peirce drift chummed the area (43'48.677/15'12.034E)/(43'47.900/15'15.749).

Method

Frozen sardines was the material used for chum. The chum was deployed in bags suspended into the water (up to 6 at a time), and in bait tubes which were floated between 8-15 metres astern. Once the initial set up had been accomplished chum was used at the rate of 8kgs per hour on a continually refreshing basis.

Two rods were deployed at the beginning of the drift prior to being withdrawn, drags were set very light so that the presence of juvenile sharks would be instantly evident

The SCS team worked in pairs doing two-hour shifts round the clock. As soon as any new specimens were encountered, or any events of importance occurred, the teams called Richard.

Observations

SCS worked in the Adriatic in 2005 and again in 2006, and a total of over 366 hours were achieved chumming a large number of sites. Blue sharks were found to be widely dispersed and present in most locations, however the only area where juvenile specimens were encountered was the Kornati area under investigation on this 2009 expedition.

In late June 2006 an SCS team conducted the Society's second Adriatic expedition and 9 miles southwest of Jabuka filmed a large 3 metre female Blue shark with fresh mating scarring accompanied by a mature male. The pair seemed almost pair bonded, but what is more likely, according to Dr John Stevens, is that the mating was still continuing. The female was caught on rod and line and while she was captive (prior to release) the male stayed close and mirrored her movements i.e. distress, relaxation, etc. After the female's release both animals swam off as a pair (all on film). This may have indicated the following.

• Pair bonding (unlikely)
• Mating in process (likely)
• Both of the above (unlikely)

What is sure is that it proves that end June is a time when Blue sharks are mating in the central Adriatic. Based on an estimated gestation period of 9 months to one year, pupping would be expected to start occurring from April. This is entirely consistent with the size of pups discovered on our expedition.

Offshore Sestrica (Dugi Otok/Mana Islands) Late June 2005 And October 2009-10-19

Notes

• The surface water temperature in October was 21'/22'.
• The depth of the October investigated area was 90-100 metres.
• All activity was filmed
• All sightings listed were witnessed and the data agreed by at least two observers
• Lat and Long were not recorded for the last three sightings however the rate of drift was very little and the Lat/Long of the final position on October 12th at 0135 hours was 43'47.900N and 15%15.749E.
• On October 14th we drifted just over 1 mile S.W. in 5 hours.
• We believe that 3 separate visits to this area over a 4 year period which produced confirmed sightings of pups/juvenile P. glauca on each occasion (total at least 9 specimens) is confirmation that this area is a pupping/nursery ground.

Results

The results are as indicated in the table.

Conclusion

SCS believes that the evidence supports Alen Soldo's belief that the area investigated is indeed a Blue Shark nursery. The data has all been handed to Alen who we hope will move to request that the Kornati Natural Park authorities close this area to all fishing.

N.B.

Croatia has recently introduced wide-ranging laws protecting many shark species including the Blue shark. However the central Adriatic is a favourite area for recreational anglers, and local commercial anglers who chum for tuna and swordfish. While in the Blue shark nursery we observed tuna on two occasions, chumming for tuna will also attract juvenile Blue sharks which will inevitably get caught. The law requires their release, however the Society believes that with anything but the most sensitive and careful handling by experienced people mortality among bi-catch pups will be high.