a 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 or shortly after 1898.
Because of doubts of the effectiveness of stocking fry, the Connecticut Fish Commissioners in 1895 laid out a small system of rearing ponds at Joshuatown, Lyme. Several million fry per year were stocked in those ponds and retained until October when they were drawn into the Connecticut River. The retaining ponds supposedly protected the young fish until fall when they were considered large enough to no longer need protection. Several years after these operations started, shad became more numerous and the increase was attributed to the added protection of the retaining ponds. Whatever the cause of that increase may have been, stocking a retaining pond and later releasing fingerlings did not have a similar outcome on the Housatonic. A pond known as Pecks’ Pond was leased by the state and stocked with fry to be released as fingerlings in the Housatonic but after four years’ operation, this procedure was reluctantly halted. It failed to bring back the run to that river. A recapitulation of the rearing operation shows that from 1896 through 1910, 57,029,000 shad fry were placed in the Joshuatown rearing ponds, and from 1899 through 1904, 11,500,000 shad fry were placed in Pecks’ Pond for the Housatonic. There is only passing reference to the possible morality in these ponds; one notes that the morality must be low because very few dead fish were found. It would seem that this assumption would be correct only under the most ideal conditions.”
All for major gear types have had times that historically produced significant shad landings* in Connecticut – notice the highs have occurred during the largely NAO period 1942 to 1972. (Marine Resources Management Plan for the State of Connecticut, prepared by Mark M., Blake, Marine Biologist Marine Fisheries Program, Eric M. Smith, Assistant Director, Bureau of Fisheries Marine Fisheries Program – July 1984.)
Drift gill net – flag or ring type
Highest year – 1946 - 551,000 lbs
Fykes – Anchor Set Traps or Stake Gill Net
Highest year – 1966 - 142,000 lbs
High