Effect of seasonal temperature changes on the escape behaviour of haddock, Melanogrammus aeglefinus, from the codend
Küçük Resim Yok
Tarih
2002
Yazarlar
Dergi Başlığı
Dergi ISSN
Cilt Başlığı
Yayıncı
Elsevier Science Bv
Erişim Hakkı
info:eu-repo/semantics/closedAccess
Özet
Sea temperature around the coast of Scotland rises from 7 degreesC in late winter to 12 degreesC in late summer. Recently, it was shown that the selectivity of trawl codend was poorer in late winter than it was in late summer. A change in water temperature is expected to affect the escape speed of fish, and therefore the selectivity of the gear. Four experiments carried out in this study showed the effect of this seasonal temperature change on the ability of haddock, Melanogrammus aeglefinus, to escape from a codend. A temperature increase from 7 to 12 degreesC changed the minimum twitch contraction time of the lateral muscle from 38.8 to 27.6 ms. This gives a maximum tail beat frequency of 12.78 Hz at 7 degreesC rising to 19.12 Hz at 12 degreesC. Escape reflexes of the fish were significantly slower at 7 degreesC than at 12 degreesC (P < 0.001). The shortest time to complete first body bend (stage 1) was 40 ms at 7 degreesC and 20 ms at 12 degreesC. The mean time taken to complete stage 1 at 7 degreesC (63.9 ms, S.E. 1.2) was significantly (t-test, P < 0.001) longer than at 12 degrees C (40.1 ms, S.E. 0.92). The mean time taken to complete the propulsive stroke (stage 2) of the fast start was significantly (t-test, P < 0.001) longer at 7 degrees C (108.5 ms, S.E. 5.3) than at 12 degrees C (72.6 ms, S.E. 2.6). The maximum speed recorded while competitively swimming for food reward was 7.9 L s(-1) at 7 degrees C and 12.5 L s(-1) at 12 degrees C. The observed maximum tail beat frequency used by haddock when leaving the mesh of a codend escape panel changed from 12 to 25 Hz. The general underlying physiological effect of a temperature increase of 10 degrees C was to double the speed of the maximum swimming ability (Q(10 degrees C) = 2). The effect of a change of only 5 degrees C on the ability to manoeuvre out of codend selection devices is discussed. Crown Copyright (c) 2002 Published by Elsevier Science B.V. All rights reserved.
Açıklama
Anahtar Kelimeler
selectivity, codend, escape, haddock, temperature, swimming behaviour
Kaynak
Fisheries Research
WoS Q Değeri
Q2
Scopus Q Değeri
Q1
Cilt
58
Sayı
3
