The potential impacts of climate change on fishing are of concern to recreational anglers and commercial fishermen. In 1985, nearly one billion people were engaged in recreational fishing in the United States, generating a $30-billion industry. Nearly 30% of the fishing was associated with cold-water (e.g., trout) and anadromous (those that live in the ocean and breed in fresh water e.g., salmon) fish.

Warming would have an important change on freshwater fishing in the Northeast. Most noticeable would be the significant losses of cold-water species by the end of the next century as climate change leads to a reduction of cold-water fish habitat. On the other hand, cool and warm-water fish are likely to expand their ranges into the previously cold-water habitats and increase their availability. Just as recreational freshwater fishing would be affected by climate change, so too would recreational and commercial coastal fishing. This could be particularly important because the coastal fisheries of the Northeast region comprise 18% of our nation's coastal fisheries and have already been subject to shifts and changes in fish populations.

Because the potential environmental, social, and economic impacts of climate change, and the strategies that could be employed to cope with those impacts, differ for freshwater and coastal fishing, each is explored separately in the section that follows.

With climate change, the greatest losses in cold-water species would occur along the southern border of a species' natural range. This is where the coldest temperatures are just cool enough to support survival now. Species at the northern end of their range could benefit from slightly warmer temperatures. That benefit would lead to increases in the rate of fish growth and productivity by an estimated 10 to 20 % for each 2˚F (1˚C) increase in temperature. Maturation rates would also increase if other factors continue to be positive, including having enough food available. Many species are particularly temperature-sensitive during spawning. An EPA study, which assumed a doubling of carbon dioxide levels and a rise in water temperatures about equivalent to what is expected toward the end of the 21^st century, found that the Northeast faces a 50-to100% potential loss of habitat for brown, brook, and rainbow trout -- cold-water species that are highly valued by anglers. Their study also suggested that cool-water fish losses will be concentrated in the southern sections of their habitable range. The cool-water fish include walleye, northern pike, and yellow perch. The EPA study suggests little change in the numbers of cool-water fish in the Northeast, unless cool-water fish are able to inhabit previously cold water habitats and could then increase their abundance.

Stream flow in the Northeast also would be affected by changes in precipitation, but these changes are much harder to project than changes in temperature. Changes in stream flow rates could affect all species by altering fish habitats in a variety of ways. The increasing trend toward heavy precipitation events could cause the stream flow to fluctuate more during the course of the year, even though the annual amount of precipitation remains the same. If the rate of stream flow is high and causes floods in the spring, food availability could be reduced and fish eggs could be destroyed. Further, high water velocity could prevent warmer temperature species from colonizing previously cold-water fish habitats because cold-water fish often prefer faster moving streams than warm- or cool-water fish.

Low water levels could decrease the availability and quality of habitat areas for fish, causing crowding, the spread of disease, and stranding in isolated pools of water. If stream flow is low enough, eggs lying at the bottom of a stream could become encased in ice in cold weather or could be scoured off the bottom as water flows by, resulting in their destruction. However, not all fish species would be hurt by reduced stream flow. In the Susquehanna River, low flow levels are a benefit to smallmouth bass populations.

As in other regions of our nation, fishing is a popular pastime in the Northeast. It is uncertain how anglers will react to changes in species distribution. They could fish the newly available species or they could move to higher elevations or travel northward looking for the original species they love to catch. Fishing and camping already have created congestion along the shorelines of regional lakes and streams. Regional population growth and increased participation in these outdoor activities could cause an increase in this crowding, putting greater pressure on recreation resources throughout the region.

Changes in the viability of recreational fishing could affect the region's economy. In New England, two million recreational anglers spent $1.3 billion and devoted 24 million days to fishing. Thirty-five percent of those fishing in New England were from out of the area. The value of freshwater fishing days in 1993 dollars in the entire region ranged from a low in New Hampshire and Vermont of $11.57, per angler, to a high of $21.49 in Maryland.

EPA estimates, in 1995, addressed the costs associated with habitat loss, temperature tolerance sensitivities in fish, fishing-day values, warm-water fishing behavior, and other potential impacts, including runoff and pollution. The results of the EPA study were mixed. Two possible future options suggested US annual losses of $95 and $85 million (in 1991 dollars). Two other options suggested that gains in the cool and warm-water fisheries would offset the losses to cold-water fish, with a final gain of about $80 million to the economy. Others have calculated that while the number of fisher-days could decrease by 50 million for cold-water anglers and increase by 64 million for warm-water species, the net economic result could be a loss of $320 million because of the lower value anglers place on warm-water species. A study by Heberling et al. in 1998, for example, found that anglers were willing to pay on average $4.00 per angler per year to avoid decreases in cold-water fishing opportunities even when accompanied by increases in warm-water fishing opportunities.

Few strategies are available to cope with potential impacts of climate change to fresh water fisheries. Climate change impacts will vary stream by stream, depending on whether and how stream flow and temperature are affected, and how riparian areas (lands along the borders of waterways) are maintained (e.g., developed or left natural; tree-lined or cleared, etc.). However, one strategy is to fish for alternative species; another is to travel north or to higher elevations to fish for cold-water species. Fisheries managers also could shift stocking patterns in favor of more cool and warm-water fish species, and over time, experience might increase the perceived attractiveness of cool- and warm-water species.

Coastal fishing also could be affected by projected changes in climate. Many factors, such as water temperature, fishing methods, and synergistic (combined) effects, including changes in predator-prey relationships, simultaneously influence the abundance of fish. It can be difficult to separate which circumstances create which results. However, some observations indicate trends in the impacts of environmental conditions on coastal fisheries.

During the 1970s and 1980s, populations in many of the Northeast's commercially important fisheries, such as cod, haddock, and yellowtail flounder plummeted. Although over-fishing is often cited as the major cause of these population declines, an additional explanation is that ocean warming played a role in altering the distribution and reproductive success of coastal species. Interactions between temperature and salinity, which can be altered with changes in temperature and precipitation, determine the range that a species can tolerate and successfully inhabit. Thus, as with freshwater species, coastal species that are already close to their range limits are more likely to be affected by climate changes. Given that the Northeast region is on the lower edge of the Acadian and the upper edge of the Virginian region for species distribution, changes in water temperatures could greatly influence changes in fish populations and distributions.

Changes in species composition already have occurred all along the North Atlantic coast. One example will be used to illustrate the complexity of this issue. Over a 30-year observation period from 1959 to 1989, the community composition shifted in Narragansett Bay, Rhode Island, from a resident cold-water, winter flounder dominant community to a migratory, warmer-water marine community. Warmer water temperatures appear to have set off a chain of circumstances that began with the loss of the winter flounder population and resulted in increased populations of invertebrates and migrant fishes.

During this period, the winter flounder population crashed on two occasions. Both times occurred during a multi-year warming trend during the winter-spring spawning period. A recovery of the winter flounder populations coincided with two successive cold winters. Moreover, large invertebrates -- such as crabs, squid, lobster (only in the Bay), and mantis shrimp -- moved into the region earlier in the season and in greater numbers. By the third decade of observation, the butterfish, originally a summer migrant species, had increased so much that it ranked fourth in abundance in the Narragansett Bay area.

Scientists have suggested that warm temperatures in late winter-early spring allow shrimp, one of the invertebrates increasing in number, to feed earlier in the year than usual. They invade the flounder's cold-water estuarine refuge and feed on its larvae at rates sufficient to remove a significant number. This same effect has been observed in the North Sea between plaice and a common shrimp.

In 1996, the combined US coastal commercial, recreational, and sport fishing industries were worth an estimated $14 billion. US coastal fisheries make up a significant portion of the world's fish catch.

Although the increased populations of invertebrates and migrant fish species in the Northeast coastal waters have compensated for the numbers of flounder lost, the individual fish were observed to be small. This poses a problem for fisheries, as many small fish do not generally support a fishing industry. The economic impacts of this reality clearly would reverberate throughout the social fabric of coastal communities, where coastal fisheries have sustained livelihoods for many generations.

Changes in the distribution and composition of fish populations have and are very likely to continue to impact the economy of the Northeast's fisheries, requiring adjustments by the fishing industry. For example, during its previous dominance, winter flounder accounted for half of the total income earned by coastal fishermen in one New England port, but this species now provides them with no significant income. The increase in lobstering could provide an economic benefit, however, the fishing industry will have to work to create market demand for the other newly established fish and shellfish populations in the Northeast. Increased monitoring of fish stocks coupled with appropriate fishing effort (i.e., harvesting species that are doing well) could mitigate some of the effects of the changing distribution and composition of fish populations. It should be noted that for commercial fishing, like agriculture in the Northeast, other impacts are likely to be much more important than climate change for some time to come. This could, however, change as the climate continues to change.