Gulf Coast Fishapalooza
Scientists puzzle over fish increase after oil spill fishing ban
Scientists and fishermen agree that a bumper crop of fish are swimming off Alabama and Mississippi this year. What they’re debating is whether a fishing ban caused by the Gulf of Mexico oil spill is responsible.
An examination of federal landings data shows that the Alabama and Mississippi commercial fleets combined to take nearly 300 million pounds of fish, crabs, shrimp and other creatures between May and September last year. The harvest was valued at more than $48 million.
Recreational anglers also kill millions of pounds of fish in both states during those months each year, though neither state nor federal officials could provide reliable statistics. The only recreational catch estimates available are based primarily on a federal telephone survey that a Congressional panel described as “fatally flawed.”
Scientists said it was too soon to draw a direct link between the lack of fishing pressure and an increased numbers of sea creatures currently in local waters, given the natural variability seen year to year.
“It is anecdotal, but everybody I talk to has observed a change. They’re saying they’ve never seen so much activity in the surf, offshore, everywhere,” said Bob Shipp, head of marine sciences at the University of South Alabama. “But, fish populations always wax and wane, both predators and prey. I certainly think the lack of fishing pressure, recreational and commercial, has contributed to what we are seeing. But it may be that we were just going to have a very productive year, regardless of the Gulf of Mexico oil spill.”
Ben Harvard, a commercial gillnet fisherman, agreed.
Harvard said that minnows were the main factor in the large numbers of predator fish — such as Spanish mackerel, bonito, redfish and ladyfish — seen off Alabama this year. Harvard said commercial fishermen watch for different kinds of minnows to turn up in early spring. Harvard said he can predict whether the predator fish he targets will turn up in large numbers based on what he sees in April and May.
“If the netters or longliners aren’t out there fishing, everybody thinks there are more fish. But it is really about the bait. This was one of those years with lots of bait, with minnows everywhere,” Harvard said. “I’m not saying the oil and lack of fishing didn’t have an effect. But the one thing I see as a fisherman is that we were going to have a good year anyway. And it’s been incredible.”
He said the last similar year was in 2006, which he described as a “big year for minnows.”
“The federal data show just how much we get from the Gulf of Mexico,” said John Valentine, a Dauphin Island Sea Lab scientist whose research suggests a number of fish populations surged during the Gulf of Mexico oil spill.
The two largest commercial harvests that were shut down for the duration of the spill were shrimp and menhaden. Gulfwide, menhaden and shrimp represent the largest harvests each year, with about 100 million pounds of shrimp caught and a billion pounds of menhaden, according to federal landings data. The two species are considered the cornerstones of the Gulf ecosystem, eaten by all manner of predators.
Looking at 2009 data for Alabama and Mississippi, the shrimp harvest between May and September totaled about 20 million pounds. Officials with the National Marine Fisheries Service said that about 4 pounds of crabs, fish, stingrays and other creatures are killed in shrimp nets for every pound of shrimp caught. Using the federal figures, that indicates the 2009 shrimp harvest may have removed about 100 million pounds of living creatures from area waters.
The 2009 menhaden harvest between May and September amounted to more than 200 million pounds.
A little more than a million pounds of blue crabs were harvested during the same period, mostly from Alabama waters.
Alabama’s gillnet fleet brought in about 260,000 pounds of Spanish mackerel and 653,193 pounds of mullet during those months.
All told, the commercial harvests and associated bycatch caught between May and September of 2009 add up to more than 300 million pounds.
“We don’t really have full understanding of the full overall impacts of the Gulf of Mexico oil spill on fish populations. There’s a lot more complexity to it than a comparison of landings and bycatch from one year to the next,” said Andy Strelcheck, a National Marine Fisheries Service scientist.
Strelcheck and others stressed the tremendous variability seen in marine populations from year to year attributed to factors such as rainfall, temperature and fishing pressure.
“I’ve seen lots of things that can influence the catch in a given year. What is the normal variability of a system and how do you tease apart the oil-related effects? We need to take everything with a grain of salt until we answer a number of questions,” said Eric Hoffmayer, a shark scientist with the University of Southern Mississippi’s Gulf Coast Research Lab.
LaDon Swann, director of the Mississippi-Alabama Sea Grant Consortium, said he didn’t question that sampling showed an increase in some fish populations. The question, he said, was whether the increase was related to fish fleeing from oil, to the fishing closure, or was a reflection of a really good year that might have been just as productive even if fishing had been open all summer.
“I will say there is an amazing amount of fish being caught out in the Gulf right now, but I’m not ready to say we’re past the spill in terms of our fish populations,” Swann said. “As I recall, they had a really good year in the herring fishery in Alaska after the Exxon spill, and then the fishery totally crashed and has never recovered.”