North Sound Gillnetting, Days 4-6
written by Janet Stalker
Today was the “day off” for both crews, as no one fished last night! By lunch time most things were finished and the new away team hit the sac in the afternoon to rest up for the three day nocturnal schedule to start that night. They headed out around 6 and had the nets set shortly after. Just before midnight a large electrical storm was approaching so the nets were pulled and the crew headed into a local marina on the North Island where they were met by the dinner delivery. They headed back out soon after the storm finished and had the nets set again by 1:15AM. They had caught 7 sharks before the nets were pulled for the storm, and unfortunately that ended up being the finally tally for the night!
However for the 4th day fishing in the area the diminished numbers are to be expected, and this number falls in range with previous years. The home team had left a makeshift truth or dare game in the lunch pails, so the game quickly got underway between all the boats over the radio. Around 4 o’clock when everyone just couldn’t laugh anymore people finally started tiring out and dozing off between checks. The rain storms came off and on all night, with some severely heavy rain around 5:30AM that had most people hiding under transport boxes to escape the pounding rain! Finally the crew made their way back to the lab for breakfast and bed!
Today we woke up around 4:30PM to start our day with a late lunch before heading back out to the North Sound. The night started with severe rainstorms that came off and on until early morning when the rain finally abated. Sitting in a boat for hours on end in the cold rain can be trying sometimes, but between all the boats we still managed to thoroughly enjoy ourselves. Once our dinner was delivered we were charged up again and shortly after the rain finally stopped.
Arriving home around 8AM we were greeted by the home crew (who had spent yesterday fixing our gillnets and working around the lab) and had some French toast before hitting our bunks. All told we caught only two sharks last night, so its safe to say we’re getting almost all of the juveniles from the North Sound. Tomorrow night will be the last night of fishing for that nursery, so hopefully we’ll get them all. But for now, its bedtime…
Well today was the last night of fishing for the North Sound. The away team went out and did their thing, but didn’t catch any sharks. Although that sounds like a disappointment, it actually is a good thing because it means we got all the sharks in the nursery! In total we ended up with 61 sharks which is right on target from previous years.
To spice things up for the away crew Grant, Jackie, and Matthias dressed up for when they went out to deliver dinner to the North Sound. Needless to say they were greeted with rounds of laughter. Matthias had also taken over the air waves as “D.J. Flip” to play some music for the away team over the radio. Everyone’s getting pretty tired from the long hours, and looking forward to the break tomorrow!
Summary of North Sound Catches
Over the six nights of fishing in the North Sound, 61 juvenile lemon sharks were captured of which 35 were newborn, 22 were recaptured with PIT tags from previous years and four were untagged but not newborn. Of these 61 sharks 30 were females and 31 males.
Of the 35 newborns, 17 were female and 18 were males with weight ranging from 0.6 kg to 1.4 kg averaging 1.0 kg; and total length ranging from 57.8 cm to 65.9 cm averaging 61.5 cm.
Of the 22 recaptured sharks, 12 were female and 10 were male with weight ranging between 1.1 kg to 2.9 kg with an average weight of 1.7 kg. The total length ranged between 61.4 cm to 81.2 cm averaging 70.2 cm.
The four untagged sharks were all about 74 cm meaning that they were probably starting their third year. It is possible that these sharks were previously marked and shed their PIT tag since prior analysis showed that over 5% lose their PIT tags over time. However the DNA sample will allow us to answer the question of prior capture. The recapture rate was about 80%.
Figure 1: Total catch in the North Sound pre-dredging (green bar) and post-dredging (red bar). The solid line is a moving average showing the precipitous drop from a population of 78 prior to dredging to about 60 after dredging in the Bimini lagoon. The variation from 1995 to 1999 resulted from more females giving birth in 1995 and 1997. The reduction in population after 1999 resulted from increased mortality of the sharks already born.