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Temperature Requirements for Embryos and Larvae of the Northern Pike, Esox lucius (Linnaeus)
Author(s) -
Hokanson Kenneth E. F.,
Mccormick J. Howard,
Jones Bernard R.
Publication year - 1973
Publication title -
transactions of the american fisheries society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.696
H-Index - 86
eISSN - 1548-8659
pISSN - 0002-8487
DOI - 10.1577/1548-8659(1973)102<89:trfeal>2.0.co;2
Subject(s) - esox , pike , larva , biology , fishery , zoology , ecology , fish <actinopterygii>
Several bioassay methods, responses, and end points were evaluated for use in determining the temperature requirements of northern pike embryos. Large differences in maximum embryo survival to hatch occurred among experiments that could not be attributed to effects of water temperature alone. Emphasis was placed on evaluating the relative effects of temperature on embryo survival by our correcting for differences in fertilization success among experiments. The most variable end point among experiments was the optimum temperature, while the most reproducible end point was the median tolerance limit (TL50). The lower and upper TL50s were 6.9 and 19.2 C for normal hatch and 6.3 and 19.9C for total hatch. The age of the embryo at the time of exposure had a great effect on these tolerance limits. Temperature shock, source of fish, and wet fertilization in hard and soft water had negligible effects on these tolerance limits. Recommendations were made for routine thermal bioassays for fish eggs. The 1‐day upper TL50 for newly hatched and swimming yolk‐sac larvae was 28.4 C when acclimated to 17.7 C. Both larval stages survived a lower limit of 3.2 C for 7 days. Newly hatched yolk‐sac larvae were more sensitive than swimming yolk‐sac larvae to 7‐day exposures to high temperatures at all acclimation temperatures (6–18 C), and partial mortality occurred over a greater temperature range. Growth of larvae was maximum at 26 C and negligible below 7 C. The high larval growth at 26 C was offset by an increased mortality rate during the first 2 weeks of life; consequently, the net biomass change was highest at 21 C.