I scanned this from the Fisherman magazine. I think it is an interesting read, all though somewhat long. It also shows how weather patterns and fish run in cycles.


FISHING REPORTS SECTION
ONSERVATIOI WATCH
byAIRistori
(732)223-5729
ARE FISH SHIFTING NORTHWARD WITH WARMER TEMPERATURES?
Will New England anglers be catching croakers in the near future?
A study by the NOAA Fisheries Northeast Science Center indicates that there was been a shift by cold water species such as cod and haddock to deeper and more northerly areas for colder temperatures, while some warm water fish seem to be expanding northward.
"About half of 36 fish stocks in the Northwest Atlantic Ocean, many of them commercially valuable species, have been shifting northward over the last four decades, with some stocks nearly disappearing from U.S. waters as they move farther offshore, according to a new study by NOAA researchers," NOAA said in a press release.
"Their findings, published in the journal Marine Ecology Progress Series, show the impact of changing coastal and ocean temperatures on fisheries from Cape Hatteras, N.C., to the Canadian border.
"Janet Nye, a postdoctoral researcher at NOAA's Northeast Fisheries Science Center (NEFSC) laboratory in Woods Hole, Mass, and the lead author of the study, looked at annual spring survey data from 1968 to 2007 for stocks ranging from Atlantic cod and haddock to yellowtail and winter flounders, spiny dogfish, Atlantic herring, and less well-known species like blackbelly rosefish. Historic ocean temperature records and long-term processes like the Atlantic Mul-tidecadal Oscillation and the North Atlantic Oscillation dating back to 1850 were also analyzed to put the temperature data into context.
" 'During the last 40 years, many familiar species have been shifting to the north, where ocean waters are cooler, or staying in the same general area but moving into deeper waters
than where they traditionally have been found,' Nye said. They all seem to be adapting to changing temperatures and finding places where their chances of survival as a population are greater.'
"Nye and co-authors Jason Link, Jonathan Hare and William Overholtz of NEFSC selected the 36 species to study because they were consistently caught in high numbers in the Center's annual spring bottom trawl survey. They also represented a wide range of taxonomic groups, and were known to be commercially or ecologically important. NEFSC, headquartered in Woods Hole, conducts annual spring and fall trawl surveys," the release said.
"The researchers looked at where the fish were caught and their bio-mass, or the estimated total weight of the population, in each year of the survey. For each stock they estimated the center of abundance, average depth, the range or area that the stock occupied, and the average temperature at which each stock was found.
"They also took into account fishing pressures on the species over time, as well as natural cycles in ocean temperature. Ocean temperatures have increased since the 1960s and 1970s, and the authors found significant changes in species distribution consistent with warming in 24 of the 36 stocks studied.
"Ten of the 36 stocks examined had significant range expansion, while 12 had significant range contraction. Changes in a species range can be affected by both temperature changes and fishing pressure, with heavily fished stocks appearing more sensitive
to climate change and often showing a larger shift. Seventeen of the 36 stocks occupied increasingly greater depths, and three stocks occupied increasingly shallower waters. However, the temperature at which each stock was found did not change over time, suggesting that fish are moving to remain within their preferred temperature range,"the release stated.
"Fish species can respond to changes in ocean temperature in a variety of ways. The stock can move poleward to avoid warmer water temperatures, or move into deeper waters than they have previously-been found. If fish cannot change their geographic or depth distribution, there may be changes in growth, reproduction and mortality rates. As a result, the size of the population may increase or decrease depending on the temperature preference of the species. Most species in the study were found to be responding to warming ocean temperatures in one of these ways," it said.
" The fact that we see responses in many species consistent with what you would expect with warming, but in different types of species that have experienced different historical fishing pressure, suggests that we are already witnessing the response of fish to a warming scenario,' Nye said. The community structure is changing from cool-water to warm-water fish species. These trends will likely continue.'
"While consumers will find familiar fish species at their local fish markets for the foreseeable future, fishermen may have to travel farther to catch some species until eventually it will not be economical.

" 'Consumers in the Northeast, for example, may eventually start seeing less familiar species like Atlantic croaker at local markets and on restaurant menus as southern and Mid-Atlantic species move northward into New England waters,' Nye said. The fish appear to be adapting to a changing environment, and people will as well over the next few decades.'"
"The authors say the study has implications beyond the Northeast U.S. 'It is another example of the need for an ecosystem-based management approach to our fisheries,' said co-author Jason Link, a fisheries biologist at NEFSC's Woods Hole laboratory. 'Many factors, temperature among them, influence the status of a fish stock, and we need to be aware of all of those factors and consider them in management decisions. Looking at the big picture helps put each piece of the puzzle in perspective.'"
Though the study is interesting, there are many questions - particularly from a historical perspective. Some species now rarely seen in northern waters were more common there many decades ago. The central New Jersey coast was once a hot spot for big red drum (then known as channel bass), and the biggest party boat port on western Long Island (Sheepshead Bay) was named after a southern species that used to be caught there. Spot, another southern species, used to be cyclically abundant in New York Bight - where they were called Lafayettes because the French hero of the Revolutionary War visited during one of those cycles. Another source noted that black drum were once fairly common on Long Island. In a previous Conservation Watch I detailed the surprising information that the Spanish mackerel fishery in the Atlantic got started on Long Island.
I suspect New England anglers won't be catching croakers in the near future. That species started becoming a regular visitor to the northern New Jersey coast over a decade ago, but after building up a late summer run they've become a oddball catch again the last few years,
Another possible problem with the study was the reliance on historical records from the spring and fall trawl surveys that don't necessarily provide a good sampling of many species, such as Spanish mackerel.The reliance on trawl surveys has also been a shortcoming with bottom species such as sea bass that are only found on open bottom when traveling to wrecks, reefs and rocky bottoms.