Effects of temperature and salinity on comparative embryo development and mortality of Atlantic cod (Gadus morhua L.) and haddock (Melanogrammus aeglefinus (L.))

• Published in: ICES Journal of Marine Science
• Main Authors: Laurence, Geoffrey C., Rogers, Carolyn A.
• Format: Text
• Language: English
• Published: Oxford University Press 1976
• Subjects: Articles; atlantic cod; Gadus morhua
• Online Access: http://icesjms.oxfordjournals.org/cgi/content/short/36/3/220; https://doi.org/10.1093/icesjms/36.3.220

Embryos of Atlantic cod ( Gadus morhua L.) and haddock ( Melanogrammus aeglefinus (L.) were incubated from fertilization to hatching in 36 different combinations of temperature (2–12°C) and salinity (26–36 ‰). Mortality was independent of temperature for cod, while haddock had lower mortalities at intermediate temperatures. There was an inverse relationship between salinity and mortality for both species. Mean total mortality over the combination of all temperatures and salinities was greater for haddock than cod. Highest mortalities occurred in the gastrula stage for haddock and just prior to hatching for cod. In general, cod embryos were more eurythermal and euryhaline than haddock. Highest percentages of viable hatches occurred in the ranges of 2–10°C and 28–36 ‰ for cod as compared with 4–10°C and 30–36 ‰ for haddock. Mean length at hatching was variable over the range of temperatures for cod, while the largest haddock larvae hatched at intermediate temperatures. A direct relationship was observed between salinity and mean hatching length for cod, whereas there was no association between haddock hatching length and salinity. Time to 50% hatching was inversely related to temperature and salinity for cod, and inversely related to temperature only for haddock. Haddock hatching time was less than that for cod at all combinations of temperature and salinity. Abnormalities appeared during development of both species and were independent of temperature and salinity. Experimental results are interpreted with respect to natural survival and differences between the two species.