Januari 14, 2017
>> female, sharpnose. >> all right. >> you're watching one of thelongest running studies of coastal sharks in the country. >> 75 fork length. stretch is 92. >> in 45 seconds or less,researchers identify the shark and determine its sex. shark is then examined,measured, and tagged.
the tag is inserted just underthe shark's thick skin so the creature isn't harmed. >> okay. >> fish in water. >> every shark that we collector sample, we're getting measurements from them, and it'sall going into a database that we can then look at and try andfigure out what's going on with their populations over time. so i think every shark that wecollect and take data on is
making a difference. just having the up-closeperspective to see these guys, you know, a couple of inchesfrom their face, looking at their eyes and just the shape oftheir body, is pretty interesting to me. >> the process is preciseand efficient. >> fork length is 70 1/2. stretch length is 86. he had no parasites.
flesh is nice and firm. >> a shark can't survive out ofwater for long because water must flow over the shark'sgills for it to breathe. researchers from the universityof north carolina institute of marine sciences have caught,examined, and released sharks in the same way and in the samelocations off the coast of north carolina since the study ofcoastal shark populations began back in 1972. >> by the way, the way we knowthese are sharpnose, the way
that -- one of thecarcharhinidae, which is this family of sharks that's fairlycommon, the best way you tell them apart is by thedifferent fins. and the second dorsal fin, yousee if you drew a line across the body, down here's the analfin, see how it's that far back? that's as far back asit will be. >> when you do thiscontinuously, paying attention, that you're doing it the sameway so the results are interpretable across time,it's an extraordinary ability to
actually see those ups and downsand actually get a sense at the scale that matches the lifespanof particularly these organisms, um, get a real sensefor what's happening. also, when you have changes,and those changes take place over decades, you canonly detect them when you follow them for decades. so the scale and the fact thishas been done continuously, we're now in our 43rd year ofgathering these data, is very rare and very valuable.
and it gives insights that youcannot get from anything else. >> you bait the hooks and putyour shark line out. of course, you getdifferent type of species. >> no, it's exciting. as a matter of fact, you neverknow what you're gonna expect to see or whatever. >> the first samplinglocation is about one mile off shackleford banks. the water is about 35 feet deep.
the second location is roughly7 miles farther out to sea. the water depth there isabout 70 feet. after every five hooks,a flotation buoy is attached to the line. >> generally, we put 100 hookson a given line these days. >> and they're about every15 to 16 feet. and because the long line itselfis looping down, so you have some hooks that are nearer tothe surface, some are at mid-water, some near the bottom,and then it comes back up.
so when the long line'sdeployed, it's fishing a good bit of the whole water column. >> the line is brought inafter an hour, and then the science begins. >> the way you can tell the sex,you come here to the pelvic fins, and if these extensionsare present, called claspers, it's a male. if those are absent,it's female. >> 38 species of sharks havebeen identified off the north
carolina coast in the almost45 years the project has been tracking offshoreshark populations. scientists say there are so manyspecies of sharks found here because the state is located atthe edge of the mid-atlantic and the subtropic currents. that brings plenty of fish tothe area, and an abundance of food attracts plenty of sharks. the study runs frommay through october. that's when the water warms andcoastal migrations bring the
most fish to the region. >> i think the most fascinatingthing to me is just how long they so -- they've been around. i mean, they're -- they'reobviously perfectly made for this environment. >> but, overall, the study findsthe shark population is not doing well. >> the great sharks, of whom wehad 11 species of the major great sharks, bull sharksincluded in that, all of those
11 show dramatic declines. the declines are in the order of87%, 96%, all numbers in that ballpark of allthe great sharks. okay. all 11 species of great sharksshowed evidence of decline. >> fishing for sharks and forthe fish species that sharks count on for food is believed tohave caused the dramatic decline in the numbers of great sharks. but the survey is findingthe population
of smaller sharks isdropping too. >> the record reveals thatabundances are down for all species of sharks. for the great sharks, the largeones, the -- the great hammerhead, tiger shark, bullshark, all the larger species, they're down dramatically. for those intermediate sizes,those -- for those species, the numbers are down as well. >> scientists don't know why theentire shark population is
dropping or what is bringingsharks so close to shore this summer and intocontact with swimmers. the survey continues, but thebroader question now being asked is the decline in the sharkpopulation a sign of deeper problems in the ocean. >> sharks are the top predatorsin the food chain, and they're a good indicator. if we're trying to understand ifsomething's wrong with regard to the sharks, their abundances,there's changes inwhich sharks
are there, it's one more waythat we can look at the whole coastal ecology and begin to getsome sort of sense, some real measure, of how it may or may ormay not be changing.
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