Chemical surface disinfection of eggs of Baltic cod, Gadus morhua L.

Abstract

The effect of two disinfectants on eggs and larvae of Baltic cod, Gadus morhua, was investigated. The eggs were disinfected for 10 min using various concentrations of either glutaraldehyde (100, 200, 400, 600 and 800 mg L(-1)) or iodophor (10, 50, 100 and 150 mg L(-1)), 1-4-days post-fertilization. Bactericidal effect of disinfection, survival to hatching, hatching success and larval abnormalities were assessed. Larval survival was recorded at 5-, 10- and 15-days post-hatch (dph). Although Baltic cod eggs have an unusually thin chorion, they could tolerate surface disinfection. A reduction in bacterial growth was observed with increased concentrations of disinfectant (3.0 x 10(7)-1.6 x 10(1) CFU mL(-1)). Abnormalities in newly hatched larvae were not related to disinfection. Survival of the yolk sac larvae was significantly better for eggs treated with 400 mg L(-1) glutaraldehyde for 10 min at 10 and 15 dph. Effective disinfection was also recorded using 100 mg L(-1) Actomar K30. Egg batch effect rather than initial bacterial concentration, disinfectant type or incubation method determined the survival of the eggs to hatching and survival of larvae. Because of the carcinogenic effect of glutaraldehyde, iodophor is recommended for routine disinfection of cod eggs.

Increasing Iodine Concentrations during Landlocked Fall Chinook Salmon Egg Disinfection Decrease Bacterial Numbers with No Impact on Egg Survival

“…For example, a 10-min, 100-mg/L iodine treatment caused complete mortality of California Halibut Paralichthys californicus eggs (Stuart et al 2010), and iodine concentrations above 50 mg/L led to increased egg mortality in Senegalese Sole Solea senegalensis (Martin et al 2016), Red Porgy Pagrus pagrus (Katharios et al 2007), and White Sea Bream Diplodus sargus sargus (Katharios et al 2007). However, iodine concentrations of up to 100 mg/L were safe for Baltic (Atlantic) Cod Gadus morhua and Bluefin Sea Bream Sparidentex hasta (Overton et al 2010;El-Dakour et al 2015).…”

“…However, iodine concentrations of up to 100 mg/L were safe for Baltic (Atlantic) Cod Gadus morhua and Bluefin Sea Bream Sparidentex hasta (Overton et al. ; El‐Dakour et al. ).…”

Surface disinfection of Senegalese sole (Solea senegalensis, Kaup 1858) eggs using iodine

“…As in other species, there is a wide range of concentrations that do not affect egg development, hatching and survival rates, but it is necessary to establish which of these has the highest capacity for disinfection (Salvesen & Vadstein ; Tendencia ; Overton et al . ). In the case of S. senegalensis eggs, for the developmental stage used in this study, we were able to establish a safe range from 0 to 50 mg L −1 with a maximum exposure time of 10 min.…”

“…Unlike other studies with different species, (Rach, Gaikowski, Howe & Schreier ; Treasurer, Cochrane & Grant ; Khodabandeh & Abtahi ; Overton et al . ), the disinfection with iodine did not improve hatching rates in S. senegalensis . This is likely due to the short time the eggs take to hatch (24–48 h at 17–20°C), which reduces the contact time between pathogen and egg.…”

Disinfection of teleost eggs: a review

“…) to 800 ppm for 10 min (cod (Overton et al . ) and halibut [ Hippoglossus hippoglossus L. , Salvesen et al . )].…”