Habitat Conservation

habitat

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 truly understand 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. In a sense, it’s like we’re the employees who own the company stock, but we’re not protecting our investment.

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. Tarpon is a good example. Adults use most coastal and coastal ocean habitats, and are able, to some extent, to adapt to changes in coastal habitats. But even these changes can be troublesome – changes in freshwater flow into estuaries, for example, changes patterns in baitfish abundance, which in turn impacts tarpon migrations and feeding. Most troublesome is that juveniles are the most at risk from habitat loss – they are dependent upon shallow mangrove and marsh backwaters for the first year or two of their lives. These habitats are already a mere shadow of the past, and loss and degradation continues. Without these habitats, few juvenile tarpon survive, and the future fishery suffers.

Habitats Under Seige

Diversion of fresh water from mangrove and marsh areas, filling in mangrove wetlands and salt marshes 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. 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 into estuaries, for example, is a major indirect impact that has been affecting the world’s fisheries 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 (ppt) for more than a couple weeks. (Normal ocean salinity is 30 – 35ppt, freshwater salinity is 0ppt.) So if too much 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 and food 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.

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. I argue both points. Part of the problem is that most anglers don’t have a long enough historical view to really make this statement. In Florida, for example, I have met only a few anglers with a fishing history that goes back 60 or more years, and the outlook of these oldtimers is different – there are fewer fish than there used to be. In fact, old time guides in the Florida Keys estimate that the bonefish population is only 20 to 25% of what it 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 same lack of historical context is true in most locations, though usually not to the extreme seen in 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. Similarly for striped bass – the fishery is undoubtedly much better than it was in the 1980s, but read the historical accounts of the fishery from the 1800s, and even allowing for the usual fisherman’s exaggeration, there were a lot more and larger striped bass back then.

Crunch Time

Just like in human medicine, proactive care is most effective. The 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 – and this is a lot more expensive. There are plenty of opportunities to fix past wrongs. But none of this will happen without anglers at the front.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, for example, has lost approximately 50% of mangroves already due to direct habitat impacts. 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 the total number of adults even under the best management strategy. Unfortunately, research data are not yet sufficient to determine exactly how much habitat loss contributes to how many fewer fish.

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 may be a useful tool, if used correctly, to get fish populations back on track to recovery, but if the fish don’t have healthy habitats to live in the stocking won’t be effective in the long term. 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.