Effects of short-term storage of gametes on fertilization of Pacific herring eggs

Abstract

A method is described whereby arrays of samples of Clupea pallasi eggs may be stored during their preparation. The high fertilization potential retained by the eggs during short-term storage allows them to be fertilized synchronously when sample preparation is complete. A variation of the "dry" method of storage retained maximum fertilization potential (80-85 ~ of the eggs for about 1 hr, and of milt dilution (1:8 with 17 %o S sea water), about 7 hr. Following dry storage, eggs fertilized in salinities of 0-45 %0 showed maximum rates of fertilization in salinities of 10-20 %0, and fertilization rates .> 50 0/o in salinities of 4.5-42 %0. Salinities of fertilization influenced egg diameter, median hatching time, and larval length at hatching in egg samples transferred 21/2 hr aflcer fertilization to an incubation salinity of 17 %0 at 7 ~ Fertilization rates were higher (90-95 ~ for eggs stored in 17 % S at 7 ~ prior to fertilization. Under such "wet" storage conditions, maximum fertilization potential was retained for about 2 hr. Highest fertilization rates (95-96 ~ were obtained for eggs stored and fertilized in salinities of 12-15 %0. For the species and the area of origin considered (British Columbia), wet storage of eggs should result in maximum fertilization when the eggs are stored at 4 ~ for a period not greater than 2 hr prior to fertilization in the 12-15 %0 S storage medium.

Osmotic responses of eggs and larvae of the Pacific herring to salinity and cadmium

“…Salinities (+ 0.2 %~ were prepared as described earlier. All trials were conducted at 8.5 (+ 0.1 ~ a temperature within the range normally found during the spawning and hatching period of herring in British Columbia waters (8.5-10 ~ (Alderdice & Velsen, 1971).…”

“…3) enclosed within the area of intersection of the yolk and PVF osmolality trends whose points of intersection are isosmotic loci. The trend line for hatch of viable larvae is calculated from the relation given by Alderdice and Velsen (1971); it shows the expected hatch of viable larvae at various incubation salinities for a temperature of 5 ~ C. Maximum hatch (83.4 ~ at 5 ~ C would be expected for an incubation salinity of 14.1%~ At 5 ~ C, maximum osmoregulatory scope is suggested to occur at incubation salinities of 13.2-19 0/00 (scaled from Fig. 3).…”

“…Fertilization rates ~ than 50 % occur at salinities between approximately 4.5 and 42 %0; such rates are maximized at salinities between 12 and 15 ~176 (Alderdice & Velsen, 1978). Ultimate maximum (optimum) hatch of viable larvae is calculated to occur at a temperature of 8.3 ~ and a salinity near 16.98 %~ within a plausible range of 13 to 19 %0 S (Alderdice & Velsen, 1971). McMynn & Hoar (1953) concluded that salinity tolerance of Pacific herring eggs was high between 5 and 25 ~ S (their Fig.…”

“…Both appear to be euryhaline and capable of spawning over a wide range of salinities. Some of this apparent plasticity may be indicative of the presence of physiological races; Alderdice & Velsen (1971) noted that Pacific herring eggs from ichthyoplankton samples in Russian waters were found at temperatures lethal to British Columbia herring eggs. These authors also noted the presence of a low/low-high/high interaction between salinity and temperature whereby egg development and survival are maximized at low temperatures in low salinities, and at higher temperatures in higher salinities.…”

“…Other estimates of larval tolerance show maxima near 22.6 %~ (Kurata, 1959), and 25.8 %0 (Fujita & Kokubo, 1927). Alderdice & Velsen (1971) noted that longest survival of larvae on their yolk stores occurred at salinities of 16.4-25.0 ~ We suspect that Pacific herring in British Columbia waters probably spawn most frequently in waters of intermediate salinity (24-28.7 %~ within a total range of 8-28 %0 S (Alderdice & Velsen, 1971). It has been suggested (Stevenson, 1962) that one principal cause of mortality among Pacific herring larvae may be their passive transport by currents to the open sea, where higher salinities may limit survival.…”