Scientists from Al. Deep Sea Fishing Rodeo collects samples from 15 sharks
By David Rainer
Al Dept. of Conservation/Nat. Resources
The shark category’s return to the 89th Annual Alabama Deep Sea Fishing Rodeo (ADSFR) was a resounding success with 15 sharks weighed in over the three-day event, including one on the ferry from Fort Morgan to the back of a pickup to get to the rodeo site on Dauphin Island.
The Tiger Sharks practically reigned supreme taking the top nine spots in the leaderboard. James Mullek-Russell (story on page 22) weighed in at a tiger 674.2 pounds to win the category, followed by Ethan Miller’s 658.4 pounds and Brett Rutledge’s 630.8 pounds. The top bull shark in the rodeo was a 434.2 pound weighed in by Eric Vandrlessche.
As eager onlookers and fishermen waited for the sharks to arrive at the weigh station, multitudes of marine scientists and students waited to advance the science on these predatory species.
Rodeo Assistant Judge Dr. Marcus Drymon is renowned for his knowledge of northern Gulf of Mexico shark species. He said rodeo-weighed sharks certainly provide a unique opportunity to gather a variety of samples from each species.
“I’ve been researching sharks in the north-central Gulf area with Dr. (Sean) Powers for almost 20 years,” Drymon said. “Much of the research we do involves tracking their relative trends, abundance and distribution, as well as studies of their age and growth, reproduction, movements and migrations, post-release mortality and things like that.
“Here at the Alabama Deep Sea Fishing Rodeo, we are taking the opportunity to harvest vertebrae from these very large individuals.”
Sharks don’t have bones; their skeletons are made entirely of cartilage. However, Drymon said scientists have a way to age these fish other than counting the growth rings on the otoliths (ear bones) that are present in most species of fish.
“Their vertebrae are calcified but not fully ossified,” he said. “It’s kind of a fine line, but technically speaking, sharks don’t have bones. The cartilage in their spine and the cartilage in their jaws are the closest thing they have to real bones. sharks don’t have otoliths like a bony fish. That’s how we age, say, a red snapper. Since we don’t have any, we use the following best things, which are the vertebrae. We section them and count the pairs of concentric bands to age these fish.
Drymon said scientists were able to take samples from reproductive organs, fins, liver and muscle tissue. Bile, gallbladder and kidney samples were also taken to assess general health.
“We watch their stomachs, but they’re usually empty,” he said. “They evacuated their stomachs during the capture process.”
Most of the sharks weighed at ADSFR were males, which are generally similar in length but weigh less than females, Drymon said. The rodeo has imposed length requirements on the shark category with a minimum of 80 inches for tiger, bull and hammerhead sharks and a minimum of 60 inches for blacktip.
“These sharks are great specimens, especially because they’re the largest individuals of these species, so they’re a bit rarer in the population,” he said. “So, for example, having the vertebrae of these individuals is very useful in trying to determine the maximum age of this species.”
Drymon said the impact of the rodeo harvest will have minimal effect on shark populations.
“For the species caught, their populations in the north-central Gulf of Mexico are in good condition,” he said. “We know this because we have seen their demographic trajectories slowly increase after decades of overuse. Thanks to the strict management measures of NOAA Fisheries and the State of Alabama, we see that these shark populations are beginning to recover and can support a limited and sustainable harvest.
Of course, sharks weren’t the only species studied. Marine scientists collected samples of a variety of fish during the rodeo, which saw near-perfect fishing conditions with calm seas and diminishing squalls.
Dr. Powers, a professor and director of the new School of Marine and Environmental Sciences at the University of Southern Alabama and the rodeo’s chief judge, said about 800 samples were taken each day of the rodeo.
“We collect samples of all (33) species present at the rodeo,” Powers said. “We review mercury levels, which we do regularly. We don’t expect any problems.
“We are looking at the flounder. We’ve seen a lot more dab in the last two years, at least from memory. We saw lots of big gray snapper (mangrove).
The research also focused on Alabama’s signature reef fish, the red snapper, which was weighed in at the rodeo in significant numbers.
“The really big rodeo red snapper specimens are great because one of the things we try to look at is to see if the big females are slowing down their egg production,” Powers said. “The idea is that the bigger the female the better, but it really hasn’t been tested to that extent. We think so, but there is evidence that as the fish get older, they don’t produce as many eggs.
Powers said a 20-inch red snapper was around 5 to 6 years old, and the oldest recorded red snapper was 56 years old and from Alabama waters.
“The red snapper becomes sexually mature between 3 and 4 years old,” he said. “Basically, the older and bigger they are, the more eggs they produce. That’s why we want to see these big females. Most of our fish off Alabama are probably 3 to 6 year old fish, d “about four to six or seven pounds. Once they get to about 15 pounds, they’re probably producing the maximum number of eggs. We need to see a lot of fish over 10 years old, so we’re proceeding to breeding here.
The biggest red snapper at this year’s rodeo was a Hyler Krebs-weighed in at 27.2 pounds. Clint Sheppard had 26.77 pounds, followed by Edgar Miller at 25.75 pounds.
“These are smaller than what we had five or six years ago,” Powers said. “Back then, if you weren’t over 30 pounds, you didn’t stand a chance. Not surprisingly, what I hear from anglers is that they have to go further offshore to catch the biggest red snapper. It is a product of state management for the number of days. We could manage for a bigger fish, but you wouldn’t have as many days. It’s a compromise. You can’t have both.
Not only did the marine scientists collect otoliths from the red snapper, but they also collected samples of tissues, reproductive organs, and stomach contents.
“The tissue sample will let us know what he’s eating,” Powers said. “We do chemical analysis, and different forage species have different chemicals.”
Powers said the new technology will allow scientists to get more information about plaice otoliths than before.
“For flounder, we have a new system where we take the chemistry through the otoliths from when it was a little baby fish to its age when it was caught, 5 or 6 years old,” he said. he declares. “We can construct the chemical environment that the fish was exposed to. This is new instrumentation that the Alabama Department of Conservation and Natural Resources helped us purchase. This system will tell us the salinity history and answer questions such as, did these fish grow up in the delta (Mobile-Tensaw) or did they come from Dog River or lower down in Mobile Bay?
“One of the things we want to find out is the importance of this region of the Delta. It is unique in its chemical composition. With that, we can tell the proportion of fish that use the delta. I think the Delta may explain how good recruitment is for flounder Is the Delta salty enough This delta has so much habitat and so much vegetation that a simple change of a few parts per thousand in salinity can make this area accessible or inaccessible to these fish.
Visit adsfr.com for the full ranking of all 33 fish species, jackpots and prize money.
Pictured: (Billy Pope) Marine scientists were able to obtain detailed data on the 15 sharks weighed during the Alabama Deep Sea Fishing Rodeo. The ADSFR was also an opportunity to gather information on Alabama’s signature reef fish, the red snapper. Boats head to the ADSFR weigh station at Dauphin Island, known as the sunset capital of Alabama.