Number Of Shad Research Articles

Modeling marine shad distribution using data from French bycatch fishery surveys

In the last few decades, there has been a marked decline in the number of shad (Alosa alosa and A. fallax) landed in France, which prompted the French committee of the Inter- national Union for Conservation of Nature to list shad as a 'Vulnerable' species in 2010. The fresh- water phases of shad life cycles have been extensively studied, but the marine phases remain poorly understood. The present study aimed to provide new insights into shad ecology by describ- ing the marine distributions of twaite and allis shad using a presence/absence model based on bycatch data from commercial fishery surveys. Depth and salinity were identified as the main fac- tors influencing shad distribution. Both species were primarily located in shallow areas, at depths of between 0 and 100 m. As expected for anadromous species, low-salinity areas were preferred. Substrate and latitude played minor roles in the observed distribution of shad. Our results suggest that latitudinal migration between winter and summer habitats does not occur in twaite and allis shad populations. Furthermore, substrate does not appear to be a key factor contributing to shad distribution. A better understanding of the distribution of shad species throughout their life cycles, particularly in the open sea where they are vulnerable to bycatch, would help in the selection of key protected areas for the sustainability of shad populations.

Predation on Recently Released Larval American Shad in the Susquehanna River Basin

Abstract The release of 18-d-old larvae of American shad Alosa sapidissima is a major component of a program to restore shad in the Susquehanna River. At stocking sites we documented predation by the resident fish community on recently released American shad. Fish collections were made on three occasions 30–60 min after release of 0.38, 0.67, and 1.5 million larval American shad. All 15 species captured at the stocking sites had consumed larval shad. American shad larvae were in the stomachs of nearly 90% of the 1,163 examined fish and represented over 90% of stomach contents by weight. The predation rate was greatest for juvenile smallmouth bass Micropterus dolomieu (mean, 345 larvae/fish from 15 specimens) at the site of the highest-level shad stocking. The release of larval shad apparently triggered a feeding response in some cyprinids, and consumption of larvae increased with the number of shad released for numerically dominant spotfin shiners Cyprinella spiloptera and mimic shiners Notropis volucellu...

Shad Catches and Water Temperatures in Virginia

The relationship of shad (Alosa sapidissima) runs and water temperatures has long been recognized. Although general statements concerning this relationship are present in the literature, some are contradictory and few are supported by specific evidence. Leach (1925) stated that the main body of shad arrived at the river mouths when water temperatures were 56* to 661F., while Bigelow and Schroeder (1953) said that shad enter streams from the Gulf of Maine when the water has warmed to 50' or 550F. Talbot (1954) indicated that shad runs in the Hudson River usually start about the first of April, when the water temperature is about 400F., and the peak of the run occurs between the middle of April and the middle of May when average water temperatures are 450 to 570F. The role of temperature in controlling the movements of fishes other than shad has been described by Huntsman (1936), who found in the Margaree River, Nova Scotia, that a late salmon (Salmo salar) run corresponded with delayed warming of river water. Mottley (1938) working in Paul Lake, British* Columbia, concluded that temperature acted both directly and indirectly in influencing the spawning time of rainbow trout (Salmo gairdneri kamloops). Sullivan (1954) reviewed much of the work regarding the effects of temperature on the movements and distribution of fishes. To investigate the possible effect of water temperatures on shad catches, records of catches and temperatures for 1953, 1954, 1955, and 1956 have been examined from the York River, a tributary of Che apeake Bay located 25 miles northwest of the Virginia Capes. Water temperature records were obtained with a Foxboro thermograph located at the end of the Virginia Fisheries Laboratory pier at Gloucester Point 6 miles upriver from the mouth of the York River. The mean depth of the sensitive element of the thermograph was about four feet below the surface. Since the York River water is essentially isothermal during spring, these temperatures are considered to be representative for the region of the river traversed by shad. The daily temperatures were taken as the mean of the maximum and minimum points on the thermograph, and the weekly averages represent the mean of the seven daily values. Fishermen capture shad in the York River with stake gill nets. These nets, 20 by 15 feet respectively in average length and depth, are usually set in series of from 10 to 40. Records of the numbers of nets fished daily and the numbers of shad captured were kept each year from 1953 to 1956 by a group of 15 to 23 shad fishermen who set their nets within 20 miles upriver from Gloucester Point. Daily catches were averaged to obtain a mean catch-per-unit-ofeffort for each week. Comparable weeks during the 'Contribution from the Virginia Fisheries Laboratory No. 72.