he 1890s came to a close smaller runs of shad diminished and after unprecedented heat the shad runs in the Thames and Housatonic became “extinct during or shortly after 1898” (Moss 1965), 1898 was a key habitat year, for Connecticut it was the year the lobsters in New England also died off but the cooler (deeper) Connecticut River Shad run held up the longest. The State of Connecticut tried to reverse the decline of shad runs – releasing millions of shad fry raised in fish hatcheries between 1885 to 1910. The Great Heat (1880 to 1920) was damaging to these cooler preferring fish but a climate change and habitat reversal was set to bring shad fisheries back from these low points in the 1950s and 1960s, during a much cooler period (the period is now mentioned as a negative NAO cycle). The 1950s and 1960s a period of cold and powerful storms was the best United States shad landings as catches soared to over 11 million pounds in 1958*.( It is long been recognized that barriers to returning shad (such as dams) need our help or “restoration.” Connecticut has become a national leader in restoring fish passage – and installing “fish ways” over dams. The initial interest in fish restoration can be traced to 1967 legislation under the direction of the US Fish and Wildlife Service. Connecticut DEEP continues fish restoration projects with partnerships between local groups, environmental organizations and coastal land trusts.) Previous researchers did mention this heat / habitat and the strength of the “year class” or run. Writing in 1976 William Leggett, then of the Essex Marine Laboratory, one attribute of temperature studies of four rivers found that temperature with peak returns were all “remarkably consistent” on page 173 (Merriam and Thorpe, 1976).
“On the basis of this analysis it seems reasonable to conclude that a significant elevation of temperature in northern rivers could alter the migratory behavior of the shad, perhaps causing the fish to enter the rivers earlier than normal, providing that they were in the area when optimum river temperatures developed. In rivers where the heating occurs below the spawning grounds, as is the case in the Connecticut River, this could result in a prolonged freshwater residence if the shad delayed spawning until temperatures in the spawning are were optimum or, alternatively, spawning might commence immediately, but at temperatures below the optimum, causing a reduction in egg and larval survival.”
The high heat impact of the 1880-1920 period was evidenced by the aquaculture effort developed by Connecticut in its shad “hatcheries.”
Because of the focus upon fishing effort, long term changes in fish populations were concentrated on managing fish catches rather than habitat quality, the long-term impact of temperatures was frequently missed. Habitat quality improvements often resulted in larger runs and larger catches as shad prices remained stable. The catch / abundance fishing statistics for shad long-term often reflect climate transitions – patterns and resulted habitat quality (NAO).
Douglas Moss in his 1965 report, A History of the Connecticut River and Its Fisheries, mentions the very hot period of 1898 (the year of a major lobster die-off in the Long Island Sound and Narragansett Bay – fisher reporting crabs walking out of Narragansett Bay to escape low oxygen waters) as when the Thames and Housatonic shad runs collapsed. This is the section he titled “Further Concern About Shad” on page 9. The Connecticut River run held out longer from cooler waters and its ability to collect cooling ice water melt. The high heat conditions over time are thought to have reduced habitat quality for shad as Director Moss mentions the extinction of the Thames and Housatonic rivers:
“From 1885 through 1892 eighteen million shad fry were stocked in the Housatonic River and smaller numbers in the Thames. Most of these fry were hatched from eggs of Housatonic run of shad. In spite of these operations in artificial propagation and stocking, the shad runs of the Thames and Housatonic became extinct during o