A Cause for Concern
Any fisherman who’s spent much time on the water knows that healthy habitats are essential to having quality fisheries. Unfortunately, too few anglers see how habitat loss has negatively impacted the fisheries, and even fewer are doing anything about it. If anglers want to ensure there are recreational fisheries in the years to come, they need to become involved in protecting the habitats that make up the factory that produces our coastal fisheries.

Let’s look at this as if we are newly hired managers at an assembly-line factory that has been successfully churning out product. Our job is to make sure the assembly line continues to function efficiently. Wanting to use some factory resources for other ventures, we remove a few stations from the assembly line to put into use elsewhere. For a while, this is fine – the production process can handle a few kinks in the chain. But eventually, our meddling causes whole-scale changes in the way the assembly line operates, and factory production becomes inefficient and total output falls, putting the company stock into a tailspin. In a sense, this is what we’ve done with our coastal fish stocks – our loss and degradation of coastal habitats (the assembly line) has resulted in a drop in the quantity and quality of the product (the fisheries). As both the managers of the factory and consumers of the product, anglers have the most responsibility and the most to benefit by getting the factory back on track.

Most gamefish species have at least one life stage that is especially vulnerable to habitat loss and degradation. For most coastal species, the juveniles are most at risk. Snook is a good example. To a certain extent, adults can handle many different habitat types, and are able to substitute dock pilings for mangrove prop-roots, or canals for rivers and streams as over-wintering habitats. But even these changes can be troublesome – the dock pilings provide snook little protection from larger predators like dolphin (who are less able to reach the snook along shallower mangrove shoreline), and the canals don’t stay as warm in winter as do the natural tree-lined rivers and creeks, so snook are susceptible to cold-kills in winter. But juveniles are the most at risk from habitat loss – they are dependent upon shallow mangrove backwaters for the first year or two of their lives. Without this habitat, few juvenile snook survive. Juvenile tarpon have similar habitat requirements, so are also susceptible to habitat loss or degradation.

Habitats Under Seige
Coastal habitats can be impacted in two ways – direct and indirect. Direct impacts are easy to see – things like filling in wetlands or dredging shallow creeks, actions that directly destroy or significantly alter the original habitats. Florida has lost approximately 50% of mangroves already due to direct habitat impacts. These habitats are essential to species like snook and tarpon – their juvenile life stages depend on shallow mangrove habitats. In a worst case scenario, since we have lost so many mangroves and wetlands, we may have already lost some of our ability to manage these fisheries – if juvenile habitat is a limiting factor in adult abundance, then loss of juvenile habitat may have put a cap on possible numbers of adults. Unfortunately, research data are not yet sufficient to determine exactly how much habitat loss contributes to how many fewer fish.

Indirect impacts are tougher to see, and generally don’t become items of concern until long after the damage has been done. Alteration of freshwater flow, for example, is a major indirect impact that has been affecting the world’s for many years, but only relatively recently has this become a major public issue.  Alterations of freshwater flows into estuaries change the types of species and the numbers of organisms that are present, and this has far-reaching impacts. Most species of seagrass, for example, can’t tolerate salinities less than 15 parts per thousand for more than a couple weeks. (Normal ocean salinity is 30 – 35ppt, freshwater salinity is 0ppt.)  So if freshwater is released into estuaries for long enough, the seagrasses will die, and the organisms that rely on seagrass habitats will also die or leave the area. This, of course, will result in fewer gamefish because there is less for them to eat, and no places to hide if larger predators come into the area. The same goes for mangroves and saltmarsh grasses – they can handle total freshwater for a while, but will be outcompeted by other plant species if the system changes to freshwater. And even if the plants are able to remain, many of the organisms that provide habitat for fish and their prey will die – the oysters that grow on mangrove prop-roots or line saltmarsh shorelines will die if exposed to salinities less than 15ppt for more than a week or two.

Diversion of fresh water from mangrove areas, filling in mangrove wetlands for development, cutting mangroves for wood products and pollution are all immediate threats to these habitats and to the communities that depend on them. Without these fragile habitats, many species will not be able to survive, and we will lose a fantastic habitat for fishing. To fragment these important fish habitats into ever smaller, low-quality parcels is to invite disaster for coastal gamefish, and is an outcome we should try our best to prevent.

Let’s Put it in Context
I have had some anglers tell me there are plenty of gamefish in our coastal waters, and just as many now as there used to be. But so far, none of these anglers have a long enough history (at least in Florida) to really make this statement. I have met few anglers in Florida with a fishing history that goes back 60 or more years, and their outlook is a bit different – there are fewer fish than there used to be. This is an example of what has been termed a ‘sliding historical baseline’ – each new angler’s timeline of history is shorter than the last, and the view of what is ‘good’ and ‘bad’ fishing differs accordingly. When thinking about how we want our fisheries to be, we should lean toward the longer historical baseline, and use that as a target.  This problem is not unique to Florida. When living in Massachusetts, I heard commercial fishermen claim that the Georges Bank cod fish populations had rebounded, so the restrictions should be eased. Compared to 10 years ago there might be more cod, but the populations are still extremely low compared to, say, 50 years ago.

Crunch Time
What it comes down to is this: without healthy habitats we can’t have healthy fisheries, regardless of management actions that might be taken. Fish hatcheries? Stock to your heart’s content, but if the fish don’t have healthy habitats to live in, they won’t live for long.  If for nothing other than selfish reasons, fishermen should be the most concerned about habitat loss and the most ardent supporters of habitat protections – continued loss of habitats will result in continued declines in our fisheries.

Just like in human medicine, proactive care is most effective. Top priority should be with protecting what habitats are left. Although it’s not always feasible, the next best thing is restoring what has been damaged – emergency medical care. There are plenty of opportunities to fix past wrongs. But none of this will happen without anglers at the front.

All material copyright Aaron Adams 2007, 2008, and beyond, unless noted.