Adriatic Expedition

In July/August 2005 Richard and Jacqui Peirce mounted an expedition led by Richard and Craig Ferreira in the Central Adriatic to try to evaluate predatory shark populations by conducting a three-week at sea round the clock chumming operation.

Over 308 hours of direct chumming were achieved and were supplemented by circa 100 hours of chumming carried out by anglers reporting to us, making a total of over 400 hours.

All the pre-selected sites were worked successfully except the area around Jabuka island. We only worked 3.5 hours before having to abandon the area due to adverse weather. This site was expected to provide the best chance of a White shark (Carcharodon carcharias), a Mako (Isurus oxyrinchus), a Porbeagle (Lamna nasus), and Blue Sharks (Prionace glauca).

In late June 2006 Richard and Jacqui Peirce with a small group of volunteers from the 2005 expedition returned to Jabuka to complete the programme making up for the previous year's lost days.

A total of 57 hours and 40 minutes round the clock drift chumming was achieved from four starting points.

SITE 1 - 8 miles NW Jabuka 16 hours continual chumming. One confirmed specimen Blue Shark (P. glauca) after 10 hours 15 minutes chumming. 2 metre female.

SITE 2 - 9 miles SW Jabuka. 19 hours continual chumming. Four confirmed specimens Blue shark (P. glauca). First specimen 3 metre female after 1 hour 20 minutes chumming, second specimen 2.5 metre male 45 minutes later.

* This was a mating pair see note 1.

Two further Blue sharks (P. glauca) were identified at 0220 hours and 0258 hours the next morning. They were both approximately 2.5 metre specimens and we were not able to positively confirm their sex, but Richard Peirce confirmed they were different animals.

SITE 3 - 6 miles SW Jabuka. 3 hours 40 minutes continual chumming produced no sharks of any species.

SITE 4 - 2/3 miles E Jabuka. 19+ hours of continual chumming produced two specimens at the end of our time as we were preparing to leave. The first specimen was not positively identified as the main witness (Sanja Peterka) claimed it was a Blue shark (P. glauca) and had the longest time viewing the animal (30-45 seconds). Richard Peirce, Vlado (skipper), Mark Boothman and Bob Pennington all felt it was not a Blue shark (P. glauca) and Richard identified a spindle shaped body and equal sized upper and lower caudal lobes presenting the possibility of L. nasus C. carcharias, I. oxyrinchus, or maybe Carcharhinus plumbeus, although the upper caudal lobe in this species would have been noticeably larger. The final specimen was a confirmed 2.5 metre male Blue shark.

Points Of Note

1. At Site 2 the large female Blue shark had quite noticeable mating scars and was clearly in company with the 2.5 metre male specimen. They appeared to display almost bonded behaviour which I have never witnessed before. We caught (lip hooked) the female hoping to tag her but had to release her untagged due to practical difficulties. While she was hooked, 10 minutes approximately, the male stayed very close swimming erratically in an almost distressed fashion and at no time moved away more than 8/10 metres. When we released the female she swam away unhurriedly with the male at her side only a metre or two away.

I am convinced this was a mating pair and what I observed looked like bonded behaviour (8 witnesses and a short sequence was filmed).

Question. Is there anything published on P. glauca social behaviour/bonding/mating pairs?? The whole sequence of events is as follows. The female was the first shark to appear. She stayed around the boat for 20/25 minutes and then left. The male then appeared some 20 minutes later and remained visible for approximately 15 minutes. The female reappeared 10 minutes after the male left and was then joined a minute or two later by the male and they both swam as a pair around the boat prior to the female being captured.

2. Shark number 1 at site number 4 is an annoying enigma. Richard is sure it was not P. glauca but what species it was cannot be confirmed. If Richard had seen this specimen at a glance in South Africa, South Australia, or California, the identification would have been C. carcharias. The specimen appeared just before we started packing up to leave and an extra two hours chumming did not produce a re-appearance.

3. Whilst seven sharks in 57 hours 40 minutes, one shark every 8 hours is a great improvement on last year's results, it is still, in my opinion a very low number for the amount of hours chummed. I believe this fully supports the conclusions published in Soldo/Peirce 2005 i.e central Adriatic predatory shark populations are seriously depleted with only P. glauca still being relatively common, and all other species now being rare.