Figure 2. — Setting 1-m. plankton net to collect shad eggs, 

 St. Johns River, Fla. 



River, from Crows Bluff upstream to midway 

 between Lake Harney and Lake Poinsett, a 

 distance of 70 miles; and in the James River, 

 from Newport News to Hopewell, a distance of 

 40 miles. Ripe females were taken throughout 

 the spawning areas, but usually eggs were not 

 collected in some stretches of river within 

 these areas. Most spawning grounds were on 

 flats or in adjacent river channels and, some- 

 times, below barriers. (These findings are 

 similar to those reported by Gill, 1926; Mass- 

 mann, 1952; Smith, 1907; and Worth, 1893.) 

 Dissolved oxygen was 5 p. p.m. (parts per 

 million) or more throughout spawning areas. 

 Water conditions varied from clear to very 

 turbid. The bottom generally was sand, gravel, 

 or a combination of both. The water depth 

 usually was from 3 to 30 ft. (feet), but ranged 

 up to 40 ft. in the Hudson River. In the Con- 

 necticut River, 49 percent of the eggs were 

 collected in water less than 10 ft. deep, 30 

 percent in water between 11 emd 20 ft. deep, 

 and the remainder in water from 21 to 30 ft. 

 deep. The current ranged from less than 1 to 

 more than 3 f.p.s. (feet per second) during 

 normal flow. In some streams, river flow in 

 spawning areas was always downstream, but 

 in others it was affected by tide and current 

 moving both upstream and downstream during 

 the tidal cycle. 



Shad spawn at water temperatures from 8° 

 to 26° C, but usually between 14° and 21° C. 

 In the Pamunkey River, Va., eggs were not 

 taken in abundance until the water tempera- 

 ture reached 12° C. (Massmann, 1952), In the 

 Shubenacadie River, Nova Scotia, Canada, 

 Leim (1924) collected eggs at various tem- 

 peratures but noted that spawning stopped 

 when water temperature dropped suddenly 

 from 16° to 10° C. 



Gill (1926) observed that when shad reached 

 suitable spawning grounds and were ready to 

 deposit their eggs, they moved up the flats, 

 seemingly in pairs. When spawning, they 



swam close together near the surface, their 

 back fins projecting above the water. The 

 rapid, vigorous, spasmodic movements that 

 accompanied this activity produced a splash- 

 ing in the water whichfishermen characterized 

 as "washing". Similar spawning actions were 

 observed by Leim (1924), usually in places 

 where the current was neither sluggish nor 

 swift. Leim collected newly fertilized eggs 

 with a plankton net placed downstream from 

 the disturbance. 



On two occasions in mid-May 1958, shortly 

 after sundown, we observed a school of about 

 one hundred shad in vigorous, intermittent 

 moven-ient below the Enfield Dam on the Con- 

 necticut River. The schooling fish swam in a 

 close circle near the surface, amd a wake was 

 plainly visible. Then the speed of movement 

 rapidly quickened, the circle narrowed, and 

 fish broke the surface, producing a splashing 

 or churning in the water. This frantic activity 

 lasted only a few seconds, but minutes later 

 the same, or a different school surfaced at 

 another location and repeated the routine. The 

 entire activity lasted about 15 min. (minutes). 

 Undoubtedly this was some phase of the 

 spawning cycle. Also in the afternoon and 

 evening, schools of shad on several occasions 

 moved in a "foUow-the-leader" pattern, making 

 energetic runs with a flashing of sides which 

 was probably prespawning activity. Evidently 

 heaviest spawning normally occurs in late 

 afternoon and evening. 



Shad eggs develop over a wide temperature 

 range. Canfield* reported that the eggs de- 

 veloped gradually in the .ovaries as the tem- 

 perature of the water increased and that 

 spawning occurred intermittently as the eggs 

 ripened. At 13° to 17° C, the ovaries ap- 

 parently developed a portion of the eggs at a 

 time, and that portion was spawned. As the 

 temperature increased from 17° to 20° C, 

 the ripening of the ovaries was rapid; and as 

 the water temperature increased fronn 20° to 

 24 C. the development was more rapid and 

 soon was complete. 



Shad deposit their eggs in the open waters, 

 where they are fertilized by the males. When 

 deposited, the eggs are transparent spheres, 

 pale amber or pink, and about 0.05 in. in 

 diameter. Immediately after fertilization, they 

 absorb water and increase to a diameter of 

 about 0.1 to 0.15 in. The eggs are carried by 

 the currents and, being slightly heavier than 

 water, gradually sink. Eggs which have been 

 preserved in 5 percent Formalin ^ sink at a 

 rate of 2.4 f.p.m. (feet per minute) in water 

 of about 25° C, (Massmann, 1952). 



Unpublished manuscript. Report on shad production in 

 North Carolina by H. L. Canfleld, 1937, U.S. Fisheries 

 Agent, Bureau of Commercial Fisheries Biological Lab- 

 oratory, Beaufort, N.C. 9 p. 



^ Trade names referred to in this publication do not 

 imply endorsement of commercial products. 



