Q&A with a Red Drum Researcher
This week we’re spotlighting Steve Arnott, an associate marine scientist at the South Carolina Department of Natural Resources (SCDNR) who's led our inshore fisheries lab for over eight years. The inshore lab studies the fish that depend on South Carolina’s estuaries, including the state’s most popular saltwater game fish, red drum. Mike Denson recently sat down with Arnott to get the scoop on the 100,000+ fish they see each year, how redfish are faring in South Carolina, and the impressively long life of this iconic species.
Q: Could you describe the kind of work you and your team do in the inshore fisheries section?
Steve Arnott: Inshore fishing is a way of life for many coastal residents and visitors, and it generates millions of dollars for South Carolina businesses. Our main purpose is to monitor the status of inshore fish populations over time so we can track the health of the fisheries. We also perform research in order to better understand the biology of important fish species.
Q: How many different species do you encounter?
Steve Arnott: In 2016 we captured more than 130,000 fish belonging to over 150 species. We release most of those alive where we catch them, but we also bring a small portion back to the lab for research purposes. Not all of the species we catch are targeted by anglers. However, they still play an important role in estuaries as food for bigger fish.
Q: What are the top 3 most popular sportfish species you collect when sampling?
Steve Arnott: Red drum is the most important sportfish we catch, as well as spotted seatrout and southern flounder. Other important species include fish such as sheepshead, spot, croaker, whiting and black drum – all popular among anglers.
Q: How many years have you been collecting information on red drum?
Steve Arnott: We currently have three surveys that collect red drum: a trammel net survey that began in 1990, a longline survey that began in 1994, and an electrofishing survey that began in 2001.
Q: Why do you need to use different kinds of gear?
Steve Arnott: Many of the fish we study live in different habitats at different time of their lives. Red drum is a perfect example. Small juveniles live in the upper estuaries where it’s almost freshwater. We catch those fish in our electrofishing survey. Slightly older fish live in the lower estuaries around salt marshes and oyster reefs and we catch those fish in the trammel net survey. After 3-5 years old, these fish become mature and move into deeper waters to join the spawning stock of fish. Those fish are caught by the longline survey.
Q: What kind of information do you collect on the fish you sample?
Steve Arnott: Every fish we catch is identified and counted. We also measure the length of fish and apply a tag to some species before we release them. A sub-sample of some fish species are brought back to the lab, weighed and dissected. Our main focus with those fish is to identify their sex, reproductive condition and age. We age them by removing an otolith (ear bone) from their head, cutting a thin slice, putting it under a microscope and counting the number of rings. It’s similar to aging a tree from the rings in its trunk.
Q: Why is this science important for managing fish populations?
Steve Arnott: The natural life cycle of fish means that they are born and die at certain rates. In order to keep fish populations healthy, it’s important for fishery managers to be able to keep those rates in balance. Our job is to provide information to managers so they can make informed decisions when trying to keep that balance. To do this, we perform long-term fishery surveys using standardized methods. The important points are “long-term” and “standardized methods” - that’s the only way we can meaningfully compare the situation now to what it was before.
Q: How old do red drum live and how big do they get?
Steve Arnott: The red drum we catch in our electrofishing and trammel net surveys are usually less than 5 years old, but the longline survey catches fish up to 40 years old! That means that some of the big red drum out there today were born around the time that the first Star Wars movie came out.
Q: How come in some years there are lots of red drum in the creeks and some years there don’t seem to be so many?
Steve Arnott: The majority of red drum we see in the creeks are less than two years old, so their numbers depend on spawning success in recent years. Survival of the very early fish stages varies widely from one year to the next, depending on food, temperature, and predator conditions during the first few months of life. Since conditions vary from one year to the next, numbers of juvenile fish also vary, so the numbers in the estuary habitats tend to cycle.
Q: So, in South Carolina when we go fishing we can only keep the fish 15-23 inches in length. Why can’t we keep the bigger fish?
Steve Arnott: The bigger fish are the ones that spawn and produce more fish, so without them the population would disappear. I mentioned earlier that red drum start to reproduce at around 5 years old, but they can live up to 40 years. That means that the number of spawning fish out there is an accumulation of fish that has built up over many years. You can imagine, then, that if we remove a lot of big fish it would take decades for the stock to recover. That’s a situation we want to avoid.
Q: So if it’s important to keep lots of older fish for spawning we should be careful not to injure these fish. How do we do that?
Steve Arnott: Unfortunately, some fish released by anglers die because of injuries, exhaustion or predation. That can be a problem if enough people are out there fishing, and it’s especially problematic in the summer and fall when water temperatures are highest, increasing stress on the fish. When targeting red drum, it’s best to:
- Use a rig that reduces hook damage (we recommend using a short leader, a fixed sinker weighing 3 oz. or more, and a barbless, non-offset and non-stainless hook)
- Reduce the fight time with the right gear (20-lb or higher test line)
- Keep the fish in the water
SCDNR has a leaflet with some more useful information and tips. (Editor’s note: We’ll be rolling out more information about the best rigs and handling practices for mature red drum in the coming months.)
Q: Are red drum populations healthy in SC?
Steve Arnott: If you think of a green light as healthy and a red light as unhealthy, I’d say we’re in an orange light situation at the moment. In the 1980s, there was a lot of concern about declining numbers of big adult red drum because there were few regulations and people were allowed to harvest big, old reproducing fish.
These days, regulations are much tighter, but the number of people living along the coast has increased dramatically, and with that comes more angling pressure. Most people are targeting the younger immature fish living in the estuaries. Their numbers go through strong and weak cycles, depending on good and bad reproductive years.
However, we have started seeing some signs of stress in the system and have also been approached by some old-time anglers who have concerns. A recent regional assessment of red drum along the South Carolina, Georgia and Florida coasts seemed to indicate that the stock was doing ok, but at SCDNR we’re following up with a more localized assessment to look more specifically at the stock in South Carolina.
Q: Can anglers or charter boat captains help collect information about red drum while they are fishing?
Steve Arnott: There are several ways anglers can help:
- If you catch a tagged fish, please call the number on the tag or go to the SCDNR website to report details about the tag (we’ll send you a t-shirt or a hat as a reward).
- We also have a volunteer tagging program that trains anglers to put tags in fish for us.
- We have drop-off freezers where you can donate filleted fish carcasses – that helps us collect age and reproductive information on fish caught by anglers.
- Also, when catching fish, it obviously helps if anglers follow the regulations and, if releasing fish, try to follow the best practice guidelines for keeping them alive.
Many anglers have a strong conservation ethic - they help us by being good stewards of the environment, and they provide eyes and ears on the water by reporting their concerns.
Q: What’s the most important fact you want people to know about your research?
Steve Arnott: Long-term monitoring using standardized methods is our mantra. It’s important for people to know that we’re constantly monitoring fish populations along the South Carolina coastline to ensure that they’re there for future generations to enjoy, and that we all play a part in acting as responsible stewards of the environment.
What else are you curious to learn about red drum in South Carolina? Share your questions in the comments!
About the interviewer: Mike Denson is the director of SCDNR’s Marine Resources Research Institute, where he's worked as a scientist in the mariculture section for over 20 years. He's previously written about SCDNR's red drum stocking process here.