When it comes to fisheries management, a “balanced ecosystem” is everyone’s goal. In this scenario no single species dominates, and the food chain becomes complex and diverse, so that it is well buffered from fluctuations in individual fish populations. The bad news is, we’re not there yet. The good news is there are plenty of lobsters to go around.
Landings in recent years have reinforced the status of that fishery as Maine’s most lucrative. So you can imagine the commotion caused by reports rippling up and down Maine’s coast that lobsters are being consumed by striped bass – a species favored by recreational fishermen. If the problem is real, it could foreshadow a potentially vexing future for fisheries managers as groundfish and other stocks rebound, and more and more hungry fish reduce lobster’s abundance.
Whether striped bass are having such an impact on Maine’s lobster economy is unclear, and there is little concrete data to confirm or deny it so far. The rumor mill seems powered mostly by anecdote and fishermen’s fear that lobstering’s peak is behind them.
“Lobster catches are slow coastwide now,” says Carl Wilson, lobster biologist for the Maine Department of Marine Resources. “In the larger picture, we’re not sure why the population has increased over the past 15 years to where it is now. One theory is that predators declined during that time. If that’s true, then if predators increase, you’d observe the opposite. When we have a coast that relies so much on lobster, changes up or down are met with great interest.”
Casco Bay lobsterman Steve Train worries that stripers are already a problem, based on accounts he has heard of fishermen checking the stomachs of stripers they catch and finding lobsters. If the fish aren’t following Train’s lobster boat to pick off the “shorts” he throws back, stripers are plenty thick in his home waters. “Go to any shore on Long Island, you can see the stripers swimming by. How many thousands of stripers are down there? I don’t think that’s healthy for the lobster industry.”
By mid-September no one was prepared to close the book on this year’s lobster season. The past two years saw harvest numbers down until September, when delayed molts were followed by very a good fall. Typically if lobsters molt in early July it is followed by a surge in the fishery two or three weeks later. This year has seen a protracted molt, so there hasn’t been that “bounce.” Train says it is getting too late for this year’s catch to make up to last year’s, even if the bounce does materialize.
In fair times it’s easy to relax and wax rhapsodic about “balanced ecosystems.” Any hint in a declining lobster fishery, however, is bound to send out tremors. It didn’t take Train long to mention the idea of a commercial striper fishery.
The striped bass has undergone a long rebuilding process that is one of fishery management’s success stories. A highly organized recreational constituency would oppose a commercial fishery just at a time when stripers are enjoying a comeback and rod & reel fishermen are enjoying a sporting chance at catching one. Down in the Chesapeake Bay, the ancestral home of the striped bass (they call it rock fish), heated arguments about the health of striped bass fishery raged all summer long focusing largely on the status of their primary forage food, Atlantic menhaden (we call it pogy). To sustain striped bass, many felt it was imperative to fend off giant factory trawlers who were sucking up pogies in order to supply the Omega-3 dietary supplement craze. Striped bass (and menhaden) eventually prevailed at the expense of supplement companies; the outcome demonstrates in no small way the power of the striper as an icon of hope and successful restoration.
Maine doesn’t have a commercial striped bass fishery, but several states along the Atlantic seaboard do. The closest is Massachusetts, where the season lasts 19 days and is hook and line only. Massachusetts claims it is home to the largest recreational striped bass fishery in the country, and the numbers back that up: last year, commercial fishermen took 900,000 fish, while recreational fishermen took 2.38 million. It is no surprise that Massachusetts has studied striped bass more than Maine has. The Massachusetts Division of Marine Fisheries (DMF) has tagged and released over 5,000 stripers. Some of those fish have been recaptured as far north as New Brunswick and as far south as Georgia.
3000 Stomachs
Dr. Gary Nelson, a DMF senior fisheries biologist, led a study that looked in the stomachs of over 3,000 stripers caught from 1997 to 2000 with gillnets and hook-and-line. The amount of lobster found in striper stomachs depended on the habitat in which the fish were caught. The shore north of Boston is a rocky coast much like Maine’s. There, says Nelson, the primary prey for 28 to 30-inch fish was juvenile lobster under two inches in carapace length. “In June and July, lobster comprised 28 to 51 percent of the diet for seven and eight year-old fish. In August and September, it was 17 percent,” says Nelson. “It could already be happening with stripers in Maine. It’s hard to say if that is a real cause for concern to the lobster fishery.”
Since any decrease could be a cause for concern for fishermen, Nelson offers the possibility that the high incidence of lobster in bass stomachs may result from a high abundance of stripers in the past few years coincident with a low abundance of menhaden. “It may simply indicate a lack of forage they prefer to eat,” says Nelson.
Massachusetts’ example suggests that stripers merit careful observation.
Nelson’s study stopped after 2000 due to lack of funding, but in 2000 the Maine Department of Marine Resources (DMR) began an inshore trawl survey that looks at important nursery grounds in the littoral area with complex bottom – kelps, eelgrass, seaweeds and habitat structure. The project started with four staffers and is down to two now, again due to lack of funding. Stomach contents recently were recently added as part of the study.
“Fish will eat what’s easiest for them to catch, they’re not strict,” says DMR biologist John Sowles. “If stripers come across a lobster they can fit down their gullet, they’ll eat it. That’s one reason [forage fish] restoration is so important: to provide a more plentiful forage prey for the predators.” Sowles points out that eagle, cormorant, seal, and osprey populations are all going up, and toxics are gradually being reduced in the ecosystem.
Which brings us back to “balanced” ecosystems. ” As predators of all kinds rebound in the richness and diversity of a healthy marine ecosystem, lobster could well play a less dominant role. “We’ve always argued for a healthy, balanced ecosystem. It’s in everybody’s interest,” says , executive director of the Maine Lobstermen’s Association. “Besides, we have all the fishermen in the state fishing on our stock, because other fisheries are down.”
Rebounding striped bass and groundfish stocks offer increased diversity and “balance” in the marine ecosystem, and increased lobster predation. The situation promises challenging days ahead in fisheries management.