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Migration in Birds and Fishes

1949; Brill; Volume: 28; Issue: 1 Linguagem: Inglês

10.1163/26660644-02801054

2666-0644

J. Verwey,

Cephalopods and Marine Biology

So called first dates of arrival of this economically valuable species of fish are known for a long series of years.The mean date for the Scheldt is April 14, but there is much difference from year to year, the species arriving much later in cold than in warm springs.The extremes range from April ist to about April last.In the northern Zuyderzee and in the Waddenzee the early animals appear some 9 days later, a difference the isotherm of 6.5°centigrade needs to move from off the Zeeland coast to the North Sea off Den Helder.Ac- cording to REDEKE the anchovies left the Zuyderzee from July onward, but in 1948 their numbers decreased in the Waddenzee near Texel in the end of May already.Most adult (i.e. two years old) animals as a rule left the Zuyderzee before September, but young were regularly found in October and sometimes in November.Near Den Helder and in the southern part